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Horizontal eights

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bhadley0 · Jan 19, 2004 12:56 PM

#0 source
I have noticed something about the way in which the horizontal (and horizontal square) eights are flown and judged. At my last competition I was told that my eights were flown real nice but that "I needed to open them up more". The pattern diagrams show that the H- eights should fit within 90 degrees, that is the far left and far right edges of the loops should not exceed a 90 deg angle. I have measured out and marked a 90 deg angle with cones on my practice circle to fly in accordance with the rules. Granted, flown this way the H- eights do appear rather confined.
I have watched many other fliers, and some videos of top experts and invariable they tend to open the eights out past 90 deg, but are obviously scored well.
It seems odd that I would be penalized for flying the eights closer to the rule book and the way that I have learned them. Why isnt the rule book more closely followed when it comes to flying and judging the horizontal eights?
Thanks,
Brian

SRiese5283 · Jan 19, 2004 02:40 PM

#1 source
>I have noticed something about the way in which the
>horizontal (and horizontal square) eights are flown and
>judged. At my last competition I was told that my eights
>were flown real nice but that "I needed to open them up
>more". The pattern diagrams show that the H- eights should
>fit within 90 degrees, that is the far left and far right
>edges of the loops should not exceed a 90 deg angle. I have
>measured out and marked a 90 deg angle with cones on my
>practice circle to fly in accordance with the rules.
>Granted, flown this way the H- eights do appear rather
>confined.
>I have watched many other fliers, and some videos of top
>experts and invariable they tend to open the eights out past
>90 deg, but are obviously scored well.
>It seems odd that I would be penalized for flying the eights
>closer to the rule book and the way that I have learned
>them. Why isnt the rule book more closely followed when it
>comes to flying and judging the horizontal eights?
>Thanks,
>Brian

I not sure what you mean
The pattern diagrams show that the H- eights should
fit within 90 degrees, that is the far left and far right
edges of the loops should not exceed a 90 deg angle.

Do you mean 90 Degrees from the pilot? I think you were told to open them up means "FLY the tops longer"
***Why isnt the rule book more closely followed when it
comes to flying and judging the horizontal eights?***
Thanks,
Brian

Big "CAN OF WORMS"

Scott(can't answer that I don't have a PhD.)Riese

Scott Riese

Brett Buck · Jan 19, 2004 03:49 PM

#2 source
>I have noticed something about the way in which the
>horizontal (and horizontal square) eights are flown and
>judged. At my last competition I was told that my eights
>were flown real nice but that "I needed to open them up
>more".
>The pattern diagrams show that the H- eights should
>fit within 90 degrees, that is the far left and far right
>edges of the loops should not exceed a 90 deg angle. I have
>measured out and marked a 90 deg angle with cones on my
>practice circle to fly in accordance with the rules.
>Granted, flown this way the H- eights do appear rather
>confined.
>I have watched many other fliers, and some videos of top
>experts and invariable they tend to open the eights out past
>90 deg, but are obviously scored well.
>It seems odd that I would be penalized for flying the eights
>closer to the rule book and the way that I have learned
>them. Why isnt the rule book more closely followed when it
>comes to flying and judging the horizontal eights?

I can almost guarantee that I know why they told you this. What was meant was that you were trying so hard to keep the maneuvers in the specified size, that you were making other, more significant, errors. You should get some credit (really, reduced or no deduction) compared to others that fly wider than specified. But, in doing so, I bet you were making other mistakes that offset the more accurate sizes.

It's not a matter of ignoring the rule book - it's a matter of giving you a suggestion that if you flew it bigger, incurred a small deduction for the extra size, but by flying larger managed to make the shapes, intersection, and bottoms better, you would get a better score overall.

Experts intentionally make this compromise. Very tip-top experts have to make less compromises, and people who fly closest to the right size without making a lot of other mistakes generally score better.

It sounds like to me that you may be making a classic beginner mistake of trying to jam the sizes and corners as tight at possible without taking the smoothness, shapes, and precision into account. The key to doing well in stunt is to minimize the net effect of ALL the errors, not just one or two aspects. That's really the challenge of the event.

Having said that, many times the size does tend to get short shrift over the other aspects - in my opinion, anyway. But in the top competitions like the NATs it seems to be weighted to a reasonable degree and hitting the proper size is rewarded.

But nobody, and I repeat, nobody, flies within the box all the time, and NEVER EVER do you see anything smaller than the 45 dimesion unless it's a mistake. 45 is very small and near the technical limits of the airplanes to handle. I can force it in, but I make so many mistakes that I don't usually try. My cohorts and I take good note of the sizes, and try to fly as close as we can - and frequently get comments that we "fly too small". But not from the judges!

Brett

Jim Pollock · Jan 19, 2004 08:15 PM

#3 source
Brian,

Brett is absolutly correct. I have done the same as you and managed to have some minimal precision. I just could not get the job done completely right. I suggest opening the horizontal eights up to the 105-110 degree range. At that size things don't happen quite as fast and its easier to keep up with the model. To be able to have precision at 90 degrees would required much slower lap times than my airplane can actually execute and perform adequately. On the square eights, many judges are so used to looking at somewhat elongated rectangles they believe that's correct - so who are we to argue, give them what they want!!!


Jim Pollock

Bill Little · Jan 19, 2004 09:13 PM

#4 source
Oh boy..........
I cannot disagree with Brett, or Jim, on this one. I have really been trying to get to the "45*" and all, and I am losing points because it all starts to look too cramped, and I do not have the practice time to really fly smooth and precisely at this size right now. It is easier to "open up" a little bit and get much better looking maneuvers. And it's true, you do get better scores, no matter what anyone tells you! (and that is in all skill classes, this is something I observed at every contest I attended this year!)
And, believe it or not, even at the NATS I have been to.

Now guys, NO ARGUMENT over this, ok? LOL!!!!
Bill <><


Disclaimer: I am neither a NATS Champion, engine reworker, engine producer, column writer, Hobby Shop owner, *rockeet* scientist, nor otherwise. Just an old Advanced flier.

Ty Marcucci · Jan 19, 2004 10:05 PM

#5 source
I too have tried to keep every thing inside the "box" and end up falling out of a maneuver. It is easy to stall a plane if things get too tight. With a small fast OTS no problem as this is how they flew/fly. But the Classic and modern planes tend to be larger and need the room to fly. The square horizontal 8 is one that has to be flown "opened" up or it just will not look like a square 8. It's my hardest maneuver and none of them are truly easy.

Jim T. · Jan 19, 2004 10:47 PM

#6 source
I have an own design 15-size flying wing which I have not been able to get engines to work exactly right on. I can fly pretty nice horizontal 8's in 90 degrees with it. However, there is no way I can fly it that tight with square 8's. I simply can't wiggle my hand fast enough.

Jim Thomerson

Brett Buck · Jan 19, 2004 11:04 PM

#8 source
>I have an own design 15-size flying wing which I have not
>been able to get engines to work exactly right on. I can
>fly pretty nice horizontal 8's in 90 degrees with it.
>However, there is no way I can fly it that tight with square
>8's. I simply can't wiggle my hand fast enough.
>

There was a thread on this topic last year sometime. Ted and the locals had tried marking out the 45 and trying to fly that size back in the 70s. And I had flown by myself for years with only the markers to go by. Back then, your observation was definitely the case - it was really difficult to make your hand move fast enough.

We tried again last year with current airplanes. With our typical airplanes, it was possible to do it because the maneuvering speeds are a lot slower. But if you did, the airplane got so far "out of shape" that it was still not reasonable to fly 45s because of all the mistakes it induced.

We also noted that our typical "way too small" flying was actually about 105-110 degrees for a square 8, or maybe 15-20% oversize. I would guess that we (Ted, David, and I) are in the low end of the ball park among competitive fliers, along with Bill Rich. But the variation among top 10 quality fliers is really not that big - some are probably *a little bit* bigger, but not grossly different.

I said it in the other thread, and I'll say it again - before anyone argues with me, go out, mark the circle in 45 degree segments, and then try it. Then tell me a lot of people "fly too small"!

Brett

Brett Buck · Jan 19, 2004 10:53 PM

#7 source
> And
>it's true, you do get better scores, no matter what anyone
>tells you! (and that is in all skill classes, this is
>something I observed at every contest I attended this year!)
>And, believe it or not, even at the NATS I have been to.
>

I don't think any one would disagree on a certain level. But the comment about the NATs is at least misleading. There are contests where flying 60+ degrees has essentially no penalty at all. At these contests, you can give yourself a lot of room and it really doesn't cost you a thing. But under NATs quality judging, there is a definite price to pay. As a result, you rarely ever see anyone doing well when they are flying 60 deg+ high maneuvers that take up 150+degrees of the circle. In Advanced, you might get away with it to some degree (not because the standards for judging are different, but because not many people have the skills and equipment to fly any smaller without generating other errors) but not very often in Open. Not very many people's square 8's fit inside 90 degrees, but those who come the closest without a lot of other errors being induced usually end up getting rewarded.

This also tends to be a source of frustration amongst the up-and-comers. They do real well at locals flying giant smooth manevuers that take up the entire sky. Then they go to a big contest like the NWR, Golden State, NATs, and others, and they do their big smooth maneuvers and lose by 25 points to someone flying, to their eyes, "way too small". See it all the time in advanced -in fact there are a couple of classic examples around the local area, and they are REALLY getting frustrated. It's real easy to fly smooth if you fly big.

Scott Reise's comments on the "targeted scoring" are tangentially related. Scott was flying Advanced, along with many others, at the NWR one year. and Chris Cox and I were judging. Pilot after pilot came up and flew giant maneuvers (>75 degree loops), then up comes Scott and flies Expert-quality sizes. He made a few other mistakes but the better size more than made up for it, and he just killed everybody else. Afterwards, I heard some complaining and I went over and looked and saw that Scott was in the low 500's, and everybody else was clustered around 470, and they really couldn't seem to understand why. One brave soul came up and asked what she (that ought to tip it off...) was doing wrong. We went through it, and it really just boiled down that flying ~75 degrees is a severe downgrade - about 12-15 points right off the top. Even if the rest was perfect, that maneuver was only going to get a 25-28 just because of the size. Scott wasn't hitting 45, either, but his size was at most a 3-4 point deduction. So it was like he was starting with a 10 point head start on most maneuvers. He wasn't as smooth, and that cost him some, so he didn't win by 100 points, but he still just killed them and really looked like he belonged in Expert.

This is just an example, but it's really quite common for beginners to concentrate on very hard corners and small maneuvers, then progress to flying too large so they can smooth it out. As you progress further, you start getting talented enough, and trim well enough, to start shrinking the maneuvers down and getting tighter corners. This is really what separates the top guys, in most cases. But chasing the size really kills beginners - the progression above, within limits, is probably the optimum path.

Brett

DMoon · Jan 20, 2004 12:11 AM

#9 source
This is an excellent thread. Listen to what Brett is saying and apply it. I used to think I was flying to small but then I would go to the Nats and it would work out fine.

There is one key element to flying small and making it look pretty and not rushed or cramped...ENGINE RUN! You have to really have it working and the boost from your motor will need to be VERY controled!

ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!ENGINE RUN!!!

I hope you are getting my point. If you are using speed and accelleration to create line tension flying small towards the rulebook size is going to be difficult.

Doug Moon

SRiese5283 · Jan 20, 2004 01:33 AM

#12 source
That event was special for me. I had a plane that was ready as well as the pilot. I haven’t been able to fly like that since I re-injured my back in 2001. This year I will bring out that same plane for this years work. I hope to get an Impact from UH and a RO-65 this spring.

Brett one thing in this thread is; and help me out here 90 degrees from WHO…the Judges or the pilot. Different distances and different angles.

Scott (thanks for the kind words) Riese

Scott Riese

Iskandar Taib · Jan 20, 2004 04:41 AM

#13 source
LAST EDITED ON Jan-20-04 AT 04:42 AM (CDT)
 
>Brett one thing in this thread is; and help me out here 90
>degrees from WHO…the Judges or the pilot. Different
>distances and different angles.

It's got to be the pilot. If it's the judges, then the angle is only half of what the pilot sees, since they're on the edge of the circle and the distance is twice as much. If the pilot sees 90 degrees, the judges see 45 degrees from their viewpoint. 90 degrees from the judges' viewpoint would be 180 degrees to the pilot.

Trostle · Jan 20, 2004 08:07 AM

#14 source
>
>Brett one thing in this thread is; and help me out here 90
>degrees from WHO…the Judges or the pilot. Different
>distances and different angles.
>
>Scott (thanks for the kind words) Riese

The width of the horizontal eights are defined by a 90-degree segmment of the circle. That 90-degree segment is one-fourth of the circle regardless from where it is being looked at.

Keith

SRiese5283 · Jan 20, 2004 10:58 AM

#16 source
>>
>>Brett one thing in this thread is; and help me out here 90
>>degrees from WHO…the Judges or the pilot. Different
>>distances and different angles.
>>
>>Scott (thanks for the kind words) Riese
>
>The width of the horizontal eights are defined by a
>90-degree segmment of the circle. That 90-degree segment is
>one-fourth of the circle regardless from where it is being
>looked at.

Thank You
scott

Scott Riese

Brett Buck · Jan 20, 2004 12:55 PM

#18 source
>>
>>Brett one thing in this thread is; and help me out here 90
>>degrees from WHO…the Judges or the pilot. Different
>>distances and different angles.
>>
>>Scott (thanks for the kind words) Riese
>
>The width of the horizontal eights are defined by a
>90-degree segmment of the circle. That 90-degree segment is
>one-fourth of the circle regardless from where it is being
>looked at.

Of course this is true - but once again, from a practical standpoint, anything you might use as a gauge to "90 deg." is inevitably subject to parallax issues, which depends quite heavily on the point of view of the observer. Just like 45 degrees high - it's obvious that you can't stand right off the side of the circle, hold up a 45 degree triangle, and get a legitimate reading on the height.
Brett

Bill Little · Jan 20, 2004 08:31 AM

#15 source
>> And
>>it's true, you do get better scores, no matter what anyone
>>tells you! (and that is in all skill classes, this is
>>something I observed at every contest I attended this year!)
>>And, believe it or not, even at the NATS I have been to.
>>
>
> I don't think any one would disagree on a certain level.
>But the comment about the NATs is at least misleading. >
> Brett

Hi Brett,
Misleading to a degree, possibly, I admit.
However, I was just pointing out that the majority (if not ALL as you stated) fly a "tiny" bit larger regarding 45*, 90* of the circle, behind the head on verticals, etc.. I concur that the pilot must decide what compromises he must make to get the highest scores, right?
The lower the class, etc., is the point I was trying to make as to better scores and the figures being larger, but I have definitely seen top 5 fliers, during the fly-offs, fly "large". This is all relative since a "top 5 large" isn't the same as a "local intermediate large".
Bill <><


Disclaimer: I am neither a NATS Champion, engine reworker, engine producer, column writer, Hobby Shop owner, *rockeet* scientist, nor otherwise. Just an old Advanced flier.

iroquois · Jan 20, 2004 12:17 AM

#10 source
Because if you argue with the judges you don't have any judges.

Randy · Jan 20, 2004 12:38 AM

#11 source
I think first you have to have a plane that is capable with a dependable engine run. Once that's accomplished and you have enough time on it to understand how the plane flies, what quirks it might have, and what you can expect from it, then you begin to (hopefully) forget about the plane and concentrate on the flying.

I often tell people I coach to make maneuvers larger when they're learning. Maybe 60 degrees and concentrate on making the shapes, intersections and bottoms correct. Once they can fly there consistently, or at least reasonably consistently, then they can start to close the maneuvers up closer to rule book size. I think it's a mistake to try to fly the rule book sizes when you can't fly shapes correctly or repeatably hit intersections and bottoms. It's just gives you less time between moves you have to make. I try to take my own advice and do at least some of the time.


Randy Powell

Ty Marcucci · Jan 20, 2004 12:47 PM

#17 source
Amen. The light has dawned. I try to fly like the rule book, but the speed of the plane seems to defy my doing so. I have been told by two very, very good flyers who were judging, to open up my maneuvers. Engine run. No two truer words for PA were ever "muttered". Most of my difficulties have been with engines that just quit or would not go back to 4 from a hot 2. I know why, but they seem to do it when you least need it. Ol Murphy has struck. I am getting better, but oh so slowly.

Keith Renecle · Jan 20, 2004 11:03 PM

#19 source
Hi Brian,

You have opened the proverbial “can of worms!” I stumbled onto this illusion last year when I was playing around with 3-D animation software. Ever since the new F2B Judges Guide came out, we have seen recommendations to place markers around the circle at 1/8th intervals, or 45 degrees. I have been running judging clinics for the last 3 years and doing exactly that. I work real hard at getting my loops round, bottoms at 5 ft. and tops at 45 degrees. I regularly get told by our judges that my horizontal eights are too big, and I “know” that my loops are spot on. I can’t even bitch at the judges, because I train them!

Last year when I drew the hemisphere in 3-D, and then stuck the correct size loop onto it, I immediately noticed that it was wider than the 45 degree markers at the base of the hemisphere. I rotated the loop back down so that the horizontal edges touched the base, (top above the line, and bottom below the line)and it fitted perfectly, spot on the marker points. I rotated it back up again, and the edges appeared wider, so I reckoned that I was simply looking at the vertical “longitude” lines that converge at the top of the hemisphere. I then drew some long vertical poles and placed them on the 1/8th interval points, and then chose a view directly from the pilot’s point of view. Same problem! The horizontal eight makes this problem even worse. I quickly phoned some of my fellow club members, and was told that I have been sniffing too much diesel fuel, and that all I had to do was to extend a vertical line down to the surface of the circle, and it would be in line with the markers. WRONG! I eventually had to build a cardboard model to scale and use two cardboard discs with a wire from the center of the discs to the center of the circle. People don’t trust computer drawings it seems! It is actually basic geometry. When you lift up the loops, the view from the pilot to the sides of the loops will keep getting wider as the angle increases. Take the same horizontal eight, and raise it up until it becomes the overhead eight. The pilot now sees the extreme edges as being directly in line with his shoulders, or 180 degrees apart. In reality, the eight has not grown suddenly in size, and always stays as a 90 degree arc. It is just the viewpoint that moves.

I have been writing to the present rule makers and various other experienced stunt people, and so far it’s only Igor Burger that believes me, so be prepared for some flak! Look at my drawing below.(Ihope that is attached!!) It shows the horizontal eight from a top view. The blue lines from the pilot shows that the 1/8th markers can be any distance from the circle edge, and they stay in line with the pilot. On the other hand, the judges have a serious problem in relating to the markers, because it depends on where they stand. The parallax errors make it very confusing, unless they stand directly inline with the markers at viewpoint 1 or 2 (VP 1 and VP 2). The purple lines show the line from the pilot to the edge of the loops. You can see the problem clearly.


The square eight, according to the present F2B rules, and also the proposed new rules, states that the extreme edges must be vertical from the surface. This means that the extreme edges will go up the longitude lines, directly in line with the markers at the 90 degree points. So in fact, they will appear narrower to the pilot and the judges, because the sides will slope inwards from the judges point of view. From VP 1 or VP 2, only the base of the square eight will be in line with the markers.

So, Brian, when you practice your round horizontal eights, they WILL appear wider than the square eights. I’m so glad that some else has noticed this. Well done! You will most likely also have to build some cardboard models to convince anyone. Good luck! There are many other problems in the pattern that cause all the comments like “ we fly the pattern to the rules, and the Chinese still win……….etc. etc.!#$?%” This is not a “sour-grapes” statement. The problem is that the rules are not defined well enough to prevent being “twisted” into many different viewpoints. Now that is a REAL “can of worms!” I’m busy with that one, so watch this space……..

Keith Renecle

Keith Renecle

Brett Buck · Jan 20, 2004 11:28 PM

#20 source
>Hi Brian,
>
>You have opened the proverbial “can of worms!” I stumbled
>onto this illusion last year when I was playing around with
>3-D animation software. Ever since the new F2B Judges Guide
>came out, we have seen recommendations to place markers
>around the circle at 1/8th intervals, or 45 degrees. I have
>been running judging clinics for the last 3 years and doing
>exactly that. I work real hard at getting my loops round,
>bottoms at 5 ft. and tops at 45 degrees. I regularly get
>told by our judges that my horizontal eights are too big,
>and I “know” that my loops are spot on. I can’t even bitch
>at the judges, because I train them!

Might want to also refer to these archived threads.

http://www.clstunt.com/cgi-bin/dcforum/dcboard.cgi?az=read_count&om=3669&forum=DCForumID1
http://www.clstunt.com/cgi-bin/dcforum/dcboard.cgi?az=read_count&om=3712&forum=DCForumID1


Brett

Keith Renecle · Jan 22, 2004 01:18 PM

#21 source
Thanks for the links to the old threads Brett. there's some good info there. I think that most of the emphasis is on the parallax problems from the judges point of view. The problem that Brian in in his question was about his hor. eight being too small when he was spot on the markers. It seems like the majority of us have been caught by this illusion, and did not notice that a correct size loop with 5ft. bottom and the top at 45 degrees, will have the sides going wider than the markers.

Keith Trostle noticed this before and mentioned on the "parallax" thread, when he stated "a 45-degree loop, from the pilot's point of view, with the bottom at the base of the hemisphere (nominally five feet above the ground), flown precisely between markers that are placed at the 45-degree radii from the center of the hemisphere will appear wider than how markers would appear that extend vertically above each of those 45-dgree locations. Likewise, the left and right sides of that round 45-degree loop are well beyond the meridians placed 45 degrees from each other going from the base of the hemisphere to the top of the circle."

So when you, as the pilot are practising with markers, it is important to note that the loops and hor. eights will appear to be wider than the markers. If the square eights are done to the rule book, then they will be spot on the markers........to the pilot.

Reading all these threads, and all the hassles fliers are having in trying to stay inside the 45 and 90 degree markers, makes me realise that the guys have not noticed this point. Since I figured this out, I've been trying to get back all the points that the judges nailed me through the years for making my eights "too big." So far they won't budge! Have fun!

Keith

Keith Renecle

dirtydan · Jan 22, 2004 01:26 PM

#22 source
Keith, meet Rich Porter.

Rich, this is Keith. Please show him your Stunt Ball, if you would, please.

You guys have a lot to talk about, if you will excuse me...

Dan

Keith Renecle · Jan 25, 2004 11:10 PM

#26 source
>Keith, meet Rich Porter.
>
>Rich, this is Keith. Please show him your Stunt Ball, if you
>would, please.
>
>You guys have a lot to talk about, if you will excuse me...
>
>Dan

Hi Dan,
I would love to see the stunt ball. Where is it??

Keith

Keith Renecle

Brett Buck · Jan 25, 2004 11:13 PM

#27 source
>Keith, meet Rich Porter.
>
>Rich, this is Keith. Please show him your Stunt Ball, if you
>would, please.
>
>You guys have a lot to talk about, if you will excuse me...
>

What's the story with Rich these days? Haven't seen him around in maybe 10 years.

Keith has, effectively, a "stunt ball" just like Porter's - but I've never seen Keith wear his as a necklace.

Brett

Keith Renecle · Jan 26, 2004 12:36 PM

#31 source
>Keith, meet Rich Porter.
>
>Rich, this is Keith. Please show him your Stunt Ball, if you
>would, please.
>
>You guys have a lot to talk about, if you will excuse me...
>
>Dan

Hi Dan,
Thanks for your input. I would love to see the stunt ball. Where is it??

Keith

Keith Renecle

Brett Buck · Jan 22, 2004 01:26 PM

#23 source
>Thanks for the links to the old threads Brett. there's some
>good info there. I think that most of the emphasis is on the
>parallax problems from the judges point of view. The problem
>that Brian in in his question was about his hor. eight being
>too small when he was spot on the markers. It seems like the
>majority of us have been caught by this illusion, and did
>not notice that a correct size loop with 5ft. bottom and the
>top at 45 degrees, will have the sides going wider than the
>markers.
>

Well, maybe, but I think it's probably a lot simpler than this, I assume that whoever told him that noted the extreme difficulty to which he was going to fit it in the box. I doubt that it was intended to mean too small as in "less than 90 degrees" or "inside the markers", but "too small" in the sense that he didn't seem to be able to fly decent shapes smoothly in whatever undefined size he was really doing. I know that this is a common bit of advice given to beginning stunt fliers, and very few people actually use size markers, and thus the parallax issue really doesn't enter in to it.

I could be wrong, of course, and the best thing to do to clarify the situation is to go back and ask whoever it was what they really meant!

Brett

ferocious · Jan 26, 2004 07:40 AM

#29 source
Another problem with the square eights, if you fly them with the out sides on the 90 deg. longitude lines- The top sides will be virtually nonexistant. On 60 ft. lines the bottom of a square loop is ~47 ft. long. Subtract 30 ft. for two 15 ft. radius corners and that leaves a 17 ft straight side. The top line of the loop is supposed to be at 45 deg. elevation(note this is NOT a straight great circle arc!). At this altitude the circle is 266 ft around, so the side of a square loop is ~33 ft.- in other words, virtually no straight side, once you allow for the 15 ft. corners.

You can make a fairly nice "square" figure if you open the dimensions up to 50-60 deg. and make the sides nearly equal and make them straight, great circle arcs. If the tops are just a bit shorter it gives the judges the illusion that you are following the book description and nobody notices that the tops are straight instead of having a "backwards" curve like they should have.

The whole point of putting markers around the circle for F2C is, I think, to encourage both the judges and the flyers to start trying to approach the 45 deg. limits in the book. As others noted, it is MUCH harder to keep the maneuvers down to that size and make them presentable. You will also have to see much lighter, larger planes that can do tighter maneuvers without falling out of the sky at the slower speeds required.

Phil C

Jim T. · Jan 26, 2004 09:11 AM

#30 source
The rule book does recognize that the tops of the horizontal square 8's will be shorter, also the tops are closer to the judges than the bottoms and thus appear relatively longer than they are. By the by, I am not sure that a square drawn on the surface of a sphere can have both four 90 degree corners and four equal sides. Have to get out my solid geometry book and check it out. All very interesting!

Jim Thomerson

Trostle · Jan 27, 2004 01:34 AM

#32 source
By the by, I am not sure that a square
>drawn on the surface of a sphere can have both four 90
>degree corners and four equal sides. Have to get out my
>solid geometry book and check it out. All very
>interesting!
>
>Jim Thomerson


It is possible to have a "square" figure on the surface of a sphere, or in our case a hemisphere. The figure will have all four sides of equal length and all four angles will be the same. Some people have a difficult time comprending and or visualizing the following.

The four sides are of equal length, but are all great circle paths. (The top of our square loops is to be a constant altitude above the ground with the lines at a 45-degree elevation -- this is not a great circle path but is really a segment of a loop which is flown at the same altitude above the ground.)

The great circle paths of this square figure of four equal length sides will appear as a straight line to the pilot who is in the four separate paths. The center of the sphere is the only location this occurs. If a person is in the plane described by one of the great circle paths, that great circle path will appear as a straight line. If the person is at the equator of the sphere and in line wth the vertical climb (or dive) then that person can see two great circle paths at the same time.

For a square figure with all sides equal and all turns equal and each side is exactly a 45-degree segment of the sphere, all four angles of the square figure will appear to be exactly 90-degrees from the viewpoint at the center of the sphere. However, the actual angle measured on the plane tangent to the surface of the hemisphere at each corner of the figure will be something less than 90 degrees, and all the corners are the same. In other words, the sum of the four corners of the square figure described here is actually less than 360-degrees as it would be if the square figure is drawn on a two dimensional flat surface. (I need to point out that this is not the square loop described in the rulebook. I also need to point out that even though we can describe a four sided figure with equal sides and equal angles, it is impossible to connect two of these things at the base of the hemisphere that we fly in without serious overlapping of the vertical intersections.

The same sort of thing happes with our triangles being flown on the surface of a hemisphere. As described in the rule book, the triangles will have all equal length sides (which are all great circle paths) and will appear to be straight paths to the pilot. The angles will also be the same. However, even the equal angle corners will appear even to the pilot as less than 120-degrees as one would expect to see of an equangular (or equal sided) triangle in two-dimensions. The larger an equangular shaped triangle become relative to the sphere on which it is drawn, the smaller the turn angle needed or all three corners - as in smaller and smalle than the 120 degrees of a flat equangular triangle. In fact, is is easy to describe and fly an equangular triangle with equal length sides on a sphere where each turn is exactly 90-degrees.

For example: Start from the base leg (normal level flight at the base of the hemisphere - a great circle path), make a 90-degree turn (inside turn for example)as if a wing over where the model is climbing up on a vertical great circle path to the center of the hemisphere top. Upon reaching the very top of the circle, make another 90-degree turn (another inside turn in this example), dive directly to the ground at a 90 degree angle to the ground (from the pilots vantage point), then recover upright (another inside turn) with another 90-degree turn. The figure has 3 equal length sides and 3 equal 90-dgree corners. This totals only 270-degrees where any triangle in two dimensions will sum to 360-degrees.

interesting stuff.

Keith

LNeumann · Jan 27, 2004 08:52 AM

#33 source
(snip)
>For a square figure with all sides equal and all turns equal
>and each side is exactly a 45-degree segment of the sphere,
>all four angles of the square figure will appear to be
>exactly 90-degrees from the viewpoint at the center of the
>sphere. (snip)

>interesting stuff.

OK, Keith, I got lost at this point. I agree with all of the other geometry stuff (especially your triangle illustration at the end) but don't understant your saying that the angles on the square will appear to be 90 degrees to the person in the center of the circle. To me, what looks like 90 degrees from the center of the circle, is what you describe in the large triangle at the end with its 90 degree turns. What looks like a 90 degree turn from the level flight in the center of the circle will, indeed, lead to the same point at the top of the circle no matter where in is begun in level flight. Thus, from the pilot's perspective, he must make the "square" corner at the bottom of the square somewhat less than 90 degrees. In fact it looks like you are leaning the sides outward--the left side appears to lean towards the left, the right side appears to lean towards the right, in order to make that perfect square. This is where a lot of beginners end up making the top of the square too narrow, because they want to go "straight up" and "straight down" with their sides, not realizing that they are flying in a sphere. The pilot has to fly a slightly different shape in order to fool the judge into seeing what he is looking for, and what the rule book describes, but in reality does not exist.

Leonard Neumann

Trostle · Jan 27, 2004 09:27 AM

#34 source
Leonard,

I have cones with a square cross section that transcribe great circle paths on the surface of a clear 14 inch hemisphere. The point of the cone is at the center of the horizontal circle (like where the pilot would stand. The pilot sees four 90-degree corners and equal length sides, as in a true square. The corners at the surface of the hemisphere are in the respective planes tangent to the surface of the hemisphere at each of those corners and are all equal but are less than 90 degrees where the sides are great circle paths and of equal length. If the bottom of the square maneuver is at the equator, the first vertical leg will appear to the pilot to be a 90-degree turn, but on the surface of the sphere, it will not be a true vertical climb (as a true properly flown wingover would be.) This is not the square maneuver described in the rule book. I have an idea that it is close to what the better flyers present and get better scores because the shape "looks right" and the "cadence" or timing of the corners "feel right" and the time along each leg "seems right".

(The square eight does not work that way. You cannot put two of these "true" square loops beside each other to make a "square eight" if the bottoms of the two loops are to be on the equator. The center vertical intersection must be "compromised". My hemisphere shows that just as Rich Porter's stunt ball of 20 - 25 years ago showed it.

Keith

Trostle · Jan 31, 2004 03:44 AM

#41 source
>(snip)
>>For a square figure with all sides equal and all turns equal
>>and each side is exactly a 45-degree segment of the sphere,
>>all four angles of the square figure will appear to be
>>exactly 90-degrees from the viewpoint at the center of the
>>sphere. (snip)
>
>>interesting stuff.
>
>OK, Keith, I got lost at this point. I agree with all of
>the other geometry stuff (especially your triangle
>illustration at the end) but don't understant your saying
>that the angles on the square will appear to be 90 degrees
>to the person in the center of the circle. To me, what
>looks like 90 degrees from the center of the circle, is what
>you describe in the large triangle at the end with its 90
>degree turns. What looks like a 90 degree turn from the
>level flight in the center of the circle will, indeed, lead
>to the same point at the top of the circle no matter where
>in is begun in level flight. Thus, from the pilot's
>perspective, he must make the "square" corner at the bottom
>of the square somewhat less than 90 degrees. In fact it
>looks like you are leaning the sides outward--the left side
>appears to lean towards the left, the right side appears to
>lean towards the right, in order to make that perfect
>square. This is where a lot of beginners end up making the
>top of the square too narrow, because they want to go
>"straight up" and "straight down" with their sides, not
>realizing that they are flying in a sphere. The pilot has
>to fly a slightly different shape in order to fool the judge
>into seeing what he is looking for, and what the rule book
>describes, but in reality does not exist.

Hi Leonard,

I might suggest that you read the post that Ted just posted on this thread and the little "game" he describes there. I have formed paper cones like he describes perfectly square cross section using square template inside the cone so that it retains its form. From the pilot's perspective, looking at the cone from its point, the pilot sees a square figure. I have a clear 14 inch diameter hemisphere and can place the cone on the inside of this hemisphere to where the bottom side of the cone is at the equator (as in normal level flight altitude - 5 feet). The edges of the cone are circular to follow the contour of the hemisphere. The bottom corners are separated by a 45-degree portion of the equator. The top corners are at the 45-degree elevation angle. The lines that the edges of the cone define on the surface of the hemisphere are all four great circle paths and are of equal length. Indeed, the sides "lean outward" if compared to a longitude from the corner at the base of the cone. The angles of the corners are all precisely the same, which to the pilot appear to be 90-degrees, but at the plane tangent to the hemisphere surface at any of those corners, the angles are less than 90 degrees. (In other words, to fly a square with all four sides the same length and each corner the same angle, the angle the plane actually turns is less than 90-degrees even though to the pilot, the turns appear to be 90-degrees.) That means that the angles of the climb and dive portions of the square are not perpendicular to the ground. The only real problem with this cone with a square cross section is that the top leg does not maintain a constant altitude at the 45-degree elevation which is specified by the rule book. That top leg is a great circle path between the two top corners which are at the 45-degree elevation point. (It is also important to understand that flight on our hemisphere at a constant 45-degree altitude is actually a loop, it is not a great circle path.)

You are correct when you observe that many flyers make the top of the squares too narrow. There is no need to do so. The rule book does not specify the angle relative to the ground of the two sides of the square. Nor does the rule book specify the angle of the top corners. Because the top leg is to be flown at a constant 45-degree elevation, the top corners are not the same angle as the bottom corners.

So it is really not necessary for a pilot "to fly a shape to fool the judge". The pilot should fly the shape as best he can as he sees it and as described by the rule book. By his location outside the circle, the judge is not in any optimum location to best view the maneuver. It is the resposibility of the judge to adjust or transcribe in his mind what he viewed to what was actually flown as viewed from the center of the circle and assess a score accordingly. I do not think anybody ever claimed that judging was easy. If anybody has made such a statement, they do not understand anything about spherical geometry.

There are some more interesting revelations here, but until most can physically see these cones bounded by a hemisphere, it can be a bit confusing.

Yes Ted, I have been enlightened by your cones. I will have them and my hemisphere at VSC. I think you will also be enlightened by the actual turn angles on the surface of the sphere to make these squares. The pilot sees 90-degrees. The airplane is actually not turning that much to fly the four great circle paths described.

Keith

Keith

LNeumann · Jan 31, 2004 08:27 AM

#42 source
Perhaps we could say this is a learned perspective, but when Matt was learning, he tried to do true 90 degree turns. That's what looked right to him. I have seen this in a lot of other beginner and Intermediate level flyers as well. The result is a trapezoid.

When I told Matt he had to pull the sides out, it looked to him like the sides were leaning out. (well, it really was, as you explain, less than 90 degrees). So I really think it is a learned experience, and not one that seems "right" at first. It really doesn't look like 90 degrees to the pilot (and really isn't) until this becomes a learned shape and he begins to fly it that way. I think we need to visualize the shape in front of us, in which case the sides of the square or the far right and left sides of the square loop are learned as not pointing up to the top of the circle.

Because we do, at first, think in terms of a 90 degree turn pointing to the top of the circle (wingover, for instance) our first impression is to make the bottom corners of the square in the same way. Eventually we learn it differently, and then it looks right, but at first there is a tendency to fly trapezoids.

Leonard Neumann

Ted Fancher · Feb 01, 2004 02:33 AM

#48 source
>
>Yes Ted, I have been enlightened by your cones. I will have
>them and my hemisphere at VSC. I think you will also be
>enlightened by the actual turn angles on the surface of the
>sphere to make these squares. The pilot sees 90-degrees.
>The airplane is actually not turning that much to fly the
>four great circle paths described.
>
>Keith

Keith,
I will no doubt be enlightened but not surprised. This is also one of the very reasons why it is easier to fly an oversize pattern!

Try to get your mind around this one. You could fly a "square 'overhead' loop" of 179 degrees included angle whose corners would amount to little more than a tiny climb every ninety degrees around the circle. You could still cut that flat square and fit it inside the maneuver "cone" just as with the smaller sized ones.

I think I'm getting a headache.

Ted

N42222 · Feb 01, 2004 10:13 AM

#50 source
It's really quite amazing the direction a thread can take- sometimes it may even return to the original question. I, too, have a headache from all these visualization attempts.(But it's fun) I took a course in sheet-metal pattern drawing and we made many of the triangles and cones Ted describes to help visualize the end result. So now my floor is covered with cardboard and my best fibreglass-cutting scissors are dulled and I'm having flashbacks to 40 years ago. Enough! I'll just endeavor to use the advise given me some years back and reiterated here, namely, just fly the plane to the shapes I visualize in two dimensions right in front of me. And let the judges sort it out! Best regards,

Ted Fancher · Feb 01, 2004 02:24 AM

#47 source
>
>For example: Start from the base leg (normal level flight
>at the base of the hemisphere - a great circle path), make a
>90-degree turn (inside turn for example)as if a wing over
>where the model is climbing up on a vertical great circle
>path to the center of the hemisphere top. Upon reaching the
>very top of the circle, make another 90-degree turn (another
>inside turn in this example), dive directly to the ground at
>a 90 degree angle to the ground (from the pilots vantage
>point), then recover upright (another inside turn) with
>another 90-degree turn. The figure has 3 equal length sides
>and 3 equal 90-dgree corners. This totals only 270-degrees
>where any triangle in two dimensions will sum to
>360-degrees.
>
>interesting stuff.


Well, close but no banana.

Hard as it might be to believe, I think if you place the flat cardboard triangle inside your super large triangle it'll still fit perfectly, 120/60 degree corners and all. I know this sounds ridiculous, but bear with me.

It might be easier to visualize if you think of the 90 degree wide triangle starting 45 degrees to the pilots left, climbing on a great circle to directly overhead (all of a sudden the "vertical" climb won't look so vertical), turn so that a great circle brings you "straight" down to a point 45 degrees to the left of the pilot and pull out back at level flight.

Again, from the pilot's percpective, this triangle will appear to be equilateral with three equal sides and three equal angles that sure as heck look like 120 degree corners to the pilot!

Interesting to note that this is precisely the same maneuver that will look totally distorted to the pilot if he were to fly the first climbing leg directly in front of him. It will appear to have a "too" vertical climbing leg and a "too" inverted or flat descending leg. Yet, if he faces it directly, it will look like a perfect equilateral triangle. do do do do, do do do do!

Point of view is everything! That's one of the reasons it is "SO" important for the pilot to face the center of his maneuvers! If he flies them off to the side he will have to distort the shape just to make it look right to him. Let's not even go there!

The huge triangle is a great way to realize the visual distortion to the pilot. Thankfully, as the maneuver gets smaller the distortion is diminished.

Spend some time thinking about this distortion and you'll start to understand how nearly preposturous it is to contemplate judging by video cam or a computer programmed to a video feed. Unless the image is viewed from the center of the circle and focused at the precise center of the maneuver the potential for distortion of the ultimate viewed image would be nearly infinite.

Guess that's why our judges get the big bucks.

Ted

Trostle · Feb 02, 2004 12:25 AM

#52 source
>>
>>For example: Start from the base leg (normal level flight
>>at the base of the hemisphere - a great circle path), make a
>>90-degree turn (inside turn for example)as if a wing over
>>where the model is climbing up on a vertical great circle
>>path to the center of the hemisphere top. Upon reaching the
>>very top of the circle, make another 90-degree turn (another
>>inside turn in this example), dive directly to the ground at
>>a 90 degree angle to the ground (from the pilots vantage
>>point), then recover upright (another inside turn) with
>>another 90-degree turn. The figure has 3 equal length sides
>>and 3 equal 90-dgree corners. This totals only 270-degrees
>>where any triangle in two dimensions will sum to
>>360-degrees.
>>
>>interesting stuff.
>
>
>Well, close but no banana.
>
>Hard as it might be to believe, I think if you place the
>flat cardboard triangle inside your super large triangle
>it'll still fit perfectly, 120/60 degree corners and all. I
>know this sounds ridiculous, but bear with me.
>
>It might be easier to visualize if you think of the 90
>degree wide triangle starting 45 degrees to the pilots left,
>climbing on a great circle to directly overhead (all of a
>sudden the "vertical" climb won't look so vertical), turn so
>that a great circle brings you "straight" down to a point 45
>degrees to the left of the pilot and pull out back at level
>flight.
>
>Again, from the pilot's percpective, this triangle will
>appear to be equilateral with three equal sides and three
>equal angles that sure as heck look like 120 degree corners
>to the pilot!
>
>Interesting to note that this is precisely the same maneuver
>that will look totally distorted to the pilot if he were to
>fly the first climbing leg directly in front of him. It
>will appear to have a "too" vertical climbing leg and a
>"too" inverted or flat descending leg. Yet, if he faces it
>directly, it will look like a perfect equilateral triangle.
>do do do do, do do do do!
>
>Point of view is everything! That's one of the reasons it
>is "SO" important for the pilot to face the center of his
>maneuvers! If he flies them off to the side he will have to
>distort the shape just to make it look right to him. Let's
>not even go there!
>
>The huge triangle is a great way to realize the visual
>distortion to the pilot. Thankfully, as the maneuver gets
>smaller the distortion is diminished.
>
snip
>
>Ted

Hi Ted,

This is almost as much fun as the "discussion" we had at VSC or whereever it was a year or so ago.

I think the triangle you describe above is essentially the same triangle I described. We both described triangles where each leg is a great circle route over a 90-degree segment of the hemisphere. To the pilot, this will appear as an equiangular triangle where indeed a flat plate can be inserted in the cone with a triangular cross section. The pilot sees 120-degree corners on that flat plate, yet the airplane is only turning 90-degree corners on the three separate planes that are tangent to the hemisphere at each of the three corners.

The same thing basically happens with the square loops where all four sides are of equal length, are great circle paths and all four corners are the same. The flat plate that describes the cross section of this four-sided cone is a true square. The pilot sees a 90-degree turn at each corner. But the angles the airplane is actually turning in the planes tangent to the hemisphere at those corners are each less than 90-degrees. The airplane is moving on the three dimensional surface of a hemisphere. It is not moving in the two dimensional flat plane that describes the cross section of the cones we are talking about.

From your post #48, you stated:

"Try to get your mind around this one. You could fly a "square 'overhead' loop" of 179 degrees included angle whose corners would amount to little more than a tiny climb every ninety degrees around the circle. You could still cut that flat square and fit it inside the maneuver "cone" just as with the smaller sized ones."

Ted, you are correct and I think with this example as well as the triangle you described above, you just helped me make my case. The square maneuver you describe would be what is projected from that flat square to the surface of the hemisphere and would still appear as a square maneuver to the pilot. However, the turn angles on the surface of the hemisphere are far less than 90-degrees. (It is just that the pilot is almost in the same plane as the flat plane that contains each of the four corners of the square rather than looking at that plate from a distance as he is doing with the "45-degree square loops" of the rulebook.)

Please be prepared to be enlightened when you get to Tucson for VSC. The cones I have and the triangles that I use to show this on my clear hemisphere are very accurate and quite enlightening.

Keith

Jim Pollock · Feb 02, 2004 09:54 AM

#53 source
Hi Keith,

Regarding the last post - or dives in the case of an outside overhead square. Then of course is the ovehead square eight which if done correctly would also fit into that section of circle nearer the equator. Hmmmm, that gives me an idea for a new maneuver - how about two overhead hourglasses rotated 90 degrees between each. The resulting maneuver could be called a paddle wheel??? Sounds pretty hard to master to me! Yeah, my head is about to melt down too, thinking about all this solid vs. plane Geometry!

Jim Pollock

LNeumann · Feb 02, 2004 10:27 AM

#54 source
>(snip) Hmmmm, that gives me an idea for a new maneuver -
>how about two overhead hourglasses rotated 90 degrees
>between each. The resulting maneuver could be
>called a paddle wheel??? (snip again)

>Jim Pollock

Why do it overhead? Just do it horizontally (or vertically--whatever) in front of you as with the clover.

Now, how are you going to work the intersections?

Your turn (Oh how these threads twist and turn )

Leonard Neumann

Jim Pollock · Feb 02, 2004 12:13 PM

#55 source
Len,

That's the beauty of doing it overhead. You just make the intersection at the 90 degree location. What kind of antics you do to make the shape are up to you as long as it looks like a paddle wheel!

Jim Pollock

ferocious · Jan 24, 2004 08:42 AM

#25 source
no wonder judges can't get my scores right. Not only can they not properly see the beautiful tricks I'm doing, the description of the tricks they think I'm flying doesn't match up with the description of the tricks I thought I read because the flibbertigibbet is catawampus to the thingamabob!!

Phil C

Ion Muniz · Jan 22, 2004 02:17 PM

#24 source
LAST EDITED ON Jan-22-04 AT 07:18 PM (CDT)
 
I found this on the archives.


Circle Parallaxes - Brett

Ion

John Sunderland · Jan 25, 2004 11:58 PM

#28 source
Its always going to be a shape/intersection...then size kind of issue!
Larger is better early on. Shrink the size as you get comfortable with a CG, throw ratio and handle spacing etc. adnauseum. If you havent made any of these trim adjustments yet...assume you got erroneous advice and earned the score you got.

John Sunderland

Keith Renecle · Jan 28, 2004 11:02 PM

#35 source
Hi All,
I just thought that you may like to see my own "stunt ball." It's the all-singing, all-dancing, PC-based stunt ball. The neat thing is that I can view any angle in true perspective. I've included a screenshot of two horizontal eights. The small one is the eight performed with round loops that fits into the 90 degree longitude lines. The 2nd eight has the correct size loops with the tops at 45 degrees. Enjoy!

Keith

Keith Renecle

Trostle · Jan 29, 2004 08:35 AM

#36 source
LAST EDITED ON Jan-29-04 AT 09:19 AM (CDT)
 
>Hi All,
>I just thought that you may like to see my own "stunt ball."
>It's the all-singing, all-dancing, PC-based stunt ball. The
>neat thing is that I can view any angle in true perspective.
>I've included a screenshot of two horizontal eights. The
>small one is the eight performed with round loops that fits
>into the 90 degree longitude lines. The 2nd eight has the
>correct size loops with the tops at 45 degrees. Enjoy!
>
>Keith

Hello Keith,

As we have been talking off-line, your graphics are great. I think what you have developed among the best I have seen as far as portraying what each of the maneuvers look like on the hemisphere we fly on. I think there is a problem with the representation of the small eight that you show on the graphic. Indeed, it is a nice round eight, but it has nothing to do with the size of eights that are to be flown by the rulebook. It shows that the eight is bounded by the logitude lines that are separated by 90-degrees. Longitude lines do NOT define the width of any of our maneuvers except their location at the equator of the hemisphere.

Our horizontal eights consist of two 45-degree loops. A 45-degree loop is the same size on our hemisphere, regardless where it is flown. The horizontal eights (as well as vertical and overhead eights) are 90-degrees in length and will be the same size, no matter where they are flown or how they are oriented on the hemisphere. Since the horizontal eights are flown with the bottoms of the two loops on the equator of the hemisphere, the horizontal axis of the eights will be elevated to approximately 22.5-degrees. In the case of our round eights, this will place the ends of the horizontal eights beyond those longitudes that are separated by 90-degrees as you CORRECTLY show with the larger 90-degree eights on your figure.

What you portray is interesting and I think that it is useful for pilots and judges alike to understand the geometry of the figures we are making on the surface of the hemisphere we fly on. But the small eight that you show bounded by the 90-degree longitudes at something around a 20 degree elevation is not the correct size as defined by the rulebook and I think it is important to emphasize and understand that.

Keith Trostle

Keith

Jim Pollock · Jan 29, 2004 09:51 AM

#37 source
Hi Keith,

I think that he is trying to show two circles on a hemisphere. As viewed from the outside you will not be able to see perfect circles from the center of the maneuver if the pilot in fact does circular loops. The result will be somewhat of an elipse and the top of the actual round figure would indeed intersect the 45 degree point. I seem to remember that anyway. Let me know if I am wrong about that please.

Jim Pollock

Keith Renecle · Jan 30, 2004 11:38 PM

#38 source
Hi Jim,
What I am trying to show is this: If you place markers outside or on the edge of the circle at 45 degree (1/8th of the circle) positions, and you practise trying to get the edges of the loops or horizontal eights spot on the markers, then your loops, or eights will be too small. This is of course if you get them dead round as well. The smaller eight in my drawing shows how small it is in relation to the correct size. If you had poles, say 100 ft. high and placed them further out and lined them up perfectly at 45 degree intervals around the circle, you could see this illusion easier.
It is only an illusion. As Keith Trostle pointed out, the loops do not grow in size! If you could fly the loops so that the center is in line with the equator (level flight, then the edges would be spot on the 45, or in the case of the horizontal eights, the 90 degree lines.
You are right about the elliptical shape. If you try to squeeze the edges into the marker lines, and get the tops at 45 degrees, then you would have the classic "egg-shaped" loops that you often see. This is especially prevalent in the horizontal eight, when fliers stretch the vertical intersection.
The new proposed F2B rules encourage markers placed around a safety fence at 1/8th intervals, so this something to watch out for. It's easy to get caught by this illusion. (ask me how I know!!)

Keith

Keith Renecle

Trostle · Jan 31, 2004 01:05 AM

#39 source
Hello again Keith,

Just to make the point again. The 45-degree markers are just what they are. The show the 45-degree positions around the circle and are vertical lines. Those markers and the vertical lines they establish are NOT representative in any way of the 45-degree longitudes that converge at a point at the top of the hemisphere. A 45-degree loop is not to be contained within the 45-degree longitudes. Rather, the width of a properly sized 45-degree loop is defined by the width of a 45-degree segment of the circle which will remain constant regardless of its position to the longitude lines except where the longitude lines cross the equator of the hemisphere.

Keith Trostle

Keith

Ted Fancher · Jan 31, 2004 02:05 AM

#40 source
LAST EDITED ON Jan-31-04 AT 10:08 AM (CDT)
 
Interesting discussion. Looks like I may even have influenced the Kernel during a few hot and heavy discussions in hotel rooms a number of years ago.

I sort of avoid these issues except in face to face discussions when your fingers don't get worn out from the bazillion exchanges necessary to get a clear case made for a given point of view. The whole concept of spherical geometry is tough enough hands on but trying to describe it in printed language seems close to impossible.

Only thing I'd like to emphasize is that we have for too long (pretty much since the first rule book) used the concept of latitude and longitude lines as a basis for describing our tricks. Much if not all of the difficulty in developing cogent descriptions can be related directly to that concept.

The only reason lat and longs exist is to enable us to navigate from one point of a sphere to another with some degree of accuracy. This is necessary because one point on a sphere is exactly like every other point. As a result, we needed some sort of artificial layering of the surface so that we could define a difference between precisely identical points on the surface.

To define navigation such a system works great. Such division, however, are completely artificial and have no basis in defining the actual surface on which we fly our tricks.

Once you make the breakthrough that Keith describes, understanding of the maneuvers becomes pretty simple (except, of course, the square eight which can't be done as described in the rule book). Once you realize that all straight sides of our tricks are great circle routes and that all loops inscribe a cone you quickly realize that a cone of given size can be place anywhere within the sphere and can be of any size.

In addition, since every point is identical and since each of those points is exactly the same distance from the pilot, the pilot will see shapes and angles exactly as though they are drawn on a flat piece of paper directly in front of his face ... in actual fact, they will actually appear more precisely geometric because the straight lines of the sides of a square loop drawn on a flat sheet, for instance, will actually appear bowed slightly in because the corners will be further from the eye than the medians of those lines.

Four equal length great circle arcs intersecting at equal angles on the surface of a sphere, on the other hand, will look truly "square" to the pilot at the center of that sphere since each point of the maneuver will be equidistant from his eye. Thus, the truly "arced" great circle paths will appear to be straight lines and the technically greater than 90 angles will appear exactly 90 degrees from that same perspective.


Just a few "for instances" to make the images clearer.

A great circle arc can begin at any point on the sphere. By definition in will depart that point and continue around the circumference of the sphere until returning to precisely the same point one lap later. Any path scribed as defined will appear to the pilot as a straight line. The only great circle arc which we routinely fly to completion is known in the rule book as level flight.

This is the one maneuver that can be accurately described by language appropriate to the lats and longs of navigation. We could call it the equator and only the strictest constructionist would quibble with that definition. (I.e., technically an equator describes points equidistant from the poles of a revolving sphere or words to that effect. Nonetheless, our level flight will pretty much track what anyone could comfortably call the "equator" of our circle )

One other place we fly half a great circle, the wingover. We don't really need to discuss why we only fly half there, do we. Once again, properly done, that wingover path will appear a straight line to the pilot.

Now it should be easy to imagine the existence of an infinite number of great circle path possibilities passing through any and all points on the surface of the sphere. Every one of our "angled" manevuers is some combination of these great circles intersecting in such locations on the surface to produce equal sides and equal angles from the perspective of the pilot and resulting in the squares, triangles and hourglass shapes required by the rule book.

Loops are all nothing more than "cones" cut out of the sphere by the lines from the innermost core (the pilot's handle)to the airplane tracking the surface of the sphere. These cones can be of any size. "Level flight" at 45 degrees is nothing more than a loop (cone)of 90 degrees included angle. Once again, that cone could be placed at any point on the surface of the sphere and have precisely the same physical properties. Horizontal (or vertical or overhead) eights are all exactly the same. Properly done they are cones of 45 degrees included angle that are tangent to one another.

By the way, a square eight is perfectly possible on the surface of a sphere. What isn't possible is to do it with eight equal sides, eight equal angles AND with the bottoms parallel to the ground!

If the requirement for the five foot bottoms was eliminated the square eight could be done perfectly square (from the pilot's perspective) with the requisite eight equal sides and angles. With the common tangent side the middle of the maneuver would have to be raised higher than five feet to permit the maneuver to be flown without flying into the ground at the ends of the squares.

A little parlor game you can use to illustrate these phenomena. Get some large sheets of fairly stiff paper and cut out perfect circles. The circles are a great circle arc (and nicely match the shape of the level flight maneuver.

Now, since with any luck the airplane will always be exactly at the rim of these circles, we can bend, fold staple and mutilate them to represent our maneuver. Take half of one circle and fold it into four equal segments and tape the edges together. What you see is four 45 degree segments ... exactly the geometrically required size of the segments for a square loop.

Here's the fun part. Cut out a flat piece of the stiff paper into a perfect square of a size that will fit into the segmented and folded structure. Place this square (with its perfect 90 degree angles and perfectly equal sides) into the heart of the segmented structure. Ta da! Notwithstanding all we've heard about spherical geometry and the resulting "greater than 90 degree angles in a square", this plane geometric square will fit perfectly into the spherical sqsuare "cone". It's magic!

The above mumbo jumbo is the reason that, whenver asked or whenever I've written about the pattern, my suggestion is that the pilot fly the maneuver to the best of his ability to shapes that look correct to him ... because, from his perspective, they will appear as plane geometric shapes and are by far the easiest for him to control to the greatest degree of perfection he is capable.

One last thing. As soon as the perspective or viewpoint from which the maneuver is seen moves away from the center of the sphere, distortion will start to take place. I guess you can worry about that if you've got a lot more neurons and synapses in your brain than I do im mine. I've pretty much decided the best course of action is to make the tricks as close to perfect from my perspective as I can make them, and then let God ...,er, the judges...sort it out.

See why I'm leary of writing about it?

Ted

Jim Pollock · Jan 31, 2004 08:18 PM

#43 source
Ted,

Nicely stated even though it is hard to put into written text!
The only thing I will point out is that in the great circle
scheme of square maneuvers is the tops will appear longer than the
bottoms due to the prespective change of actually being closer to
"God", err, that is the judges. That little prespective change will
make the maneuver appear to have inappropriate angles at the ends of
square eights anyway. Of course, the better judges know about the little prespective changes like this one.

Jim Pollock

N42222 · Jan 31, 2004 09:17 PM

#44 source
The most important great circle the Stunt flyer needs to develop is one circumnavigating his head, usually reserved for angelic personalities, but occasionally detected adorning Stunt personalities. Judges sometimes notice this phenomenon and the result is a spherical rubbery effect on their scoring! Many facets to this Stunt flying! Best regards to all y'all,

ferocious · Feb 01, 2004 09:33 AM

#49 source
That is an excellent description Ted of what is going on.

Taking the next step, the current rules, and the ongoing F2B judges guide are written using latitude and longitude as the primary reference. And the F2B judges guide will include recommendations for marking the edge of the circle at 45 deg. increments. Since the latitude/longitude descriptions and angles don't agree with the great circle/segment description that the pilots generally fly, which should be used for judging? Most of the maneuvers except for level flight, the reverse wingover and the overhead eight, have significant discrepancies.

Phil C

Brett Buck · Jan 31, 2004 09:31 PM

#45 source
>Hi All,
>I just thought that you may like to see my own "stunt ball."
>It's the all-singing, all-dancing, PC-based stunt ball. The
>neat thing is that I can view any angle in true perspective.
>I've included a screenshot of two horizontal eights. The
>small one is the eight performed with round loops that fits
>into the 90 degree longitude lines. The 2nd eight has the
>correct size loops with the tops at 45 degrees. Enjoy!

That's pretty neat - what application did you use for that? When I did it to check Keith's (by way of Pete Soule) 4-leaf rules change, I used MATLAB, but it was fussy to get right.

By the way, the aforementioned Mr. Porter's "stunt ball" is in fact a physical artifact, a clear plastic ball about 9" in diameter, with the maneuvers drawn on it's surface. He wore it on a piece of string around his neck.

Brett

Keith Renecle · Feb 01, 2004 01:14 AM

#46 source
Hi Brett,

I used 3-D software called Blender 3-D from Holland. It is used for generating games and web graphics. I actually sent you an e-mail on my project last September, but maybe you didn't receive it. I used the e-mail address from your articles in Stunt News. Let me know if you would like some more info, and if your e-mail is still the same. I could use some help on my project. Thanx.

Keith

Keith Renecle

Brett Buck · Feb 01, 2004 01:55 PM

#51 source
>Hi Brett,
>
>I used 3-D software called Blender 3-D from Holland. It is
>used for generating games and web graphics. I actually sent
>you an e-mail on my project last September, but maybe you
>didn't receive it. I used the e-mail address from your
>articles in Stunt News. Let me know if you would like some
>more info, and if your e-mail is still the same. I could use
>some help on my project.

I apologize profusely - I had missed it. It's in there, all right. I apologize for not responding, I'll get back to you once I absorb it a bit!

Brett