No line tension at top of hourglass !!

Trying to get the Time Machine40 trimmed out for the "Brodak Wars" next week, and everything is kosher, except for line tension at the top of the hourglass....big problem here.

Data:

Smith OS40FP timed for low pitch, high rpm, Bolly 11.25" x 4", launched at 10,600, strong 2-4 break.

Line length is 60 feet E/E, and lap times are around 5.2 seconds.

I had the leadouts originally 1" behind the CG, and I moved them forward to 7/8".....it seemed a little better. I'll try another 1/8" forward tomorrow.

One data point.....on the horizontal eight, I have much better line tension on the OUTSIDE loop compared to the inside loop portion, which is weak....I have to pull back on the handle. This seems to be in contradiction to the top two outside corners of the hourglass that are giving me a problem. This should be indicative of "something" but I don't know what.

I have 1 degree of engine offset, and 1/4" of rudder offset. One ounce of tip weight.

I don't have any experienced pilots in this area, so I am on my own trying to analyze the problem.

I'm finding that it is more difficult to learn how to trim a plane properly than it was to learn the maneuvers !! <g>

TIA

Cheers,

I know it's a Dixon design, and he uses equal panels. If yours is equal panel, that's not enough tip weight, most likely, but of course it depends on how the wing balances without weight, if the engine is side mounted, etc. Steve

I think you're on the right track. Keep sneaking those leadouts forward. It would probably help if you could lose the offset in the rudder & engine as well, if possible. My best results have been with the engine/rudder set at zero-zero on my stunters. Scott Riese turned me onto the FP.40/Macs muffler/10-4 black Tornado 3 blade prop setup & it really works well on my profile Oriental. Great corner & lots of line tension everywhere. If you have a chance to try it on your engine I think you'll like the way it works. This is assuming you can find the Tornado props, they're a little scarce these days. From what I've heard an 11-4 APC also works well.

Warren,
I agree with nils get the rudder straight and add tip weight.Make sure you hinge lines are sealed. Flaps and elevators.
Add tip weight until the wing starts to drop the out board tip in the corners. Then back off a little.

Have fun
Gordie

While we are all making suggestions and shooting in the dark, I would agree on the offsets and tip weight, as well as the "move the leadouts to see what happens." But I have two more suggestions.

5.2 seconds sounds a bit slow for 60 feet eyelet to eyelet. A little more speed and you will get more tension.

Second, the Bolly props are usually a little less pitch at the tips. If you are having trouble with tension overhead AND with slow lap speeds, try adding a little pitch to the tips. It doesn't take a lot. We have found this makes the props more efficient and will pick up the lap speed just a bit, also.

More tip weight, more thrust, leadout adjusted correctly, should do it.

Oh, and on those inside/outside loops, Matthew often complains of losing tension on the upper left corner of the square eight. I fly the same plane and think it is fine there, but lose it in the transition between outside and inside. Sometimes it is a matter of how you hold your hand. When I do the outside corners of the square eight, I sometimes tend to move my hand back. Then I move it forward again at the intersection and that's why I lose tension there. Watch your hand and see what you are doing. You should keep it in front of you and always pointed at the plane. Follow through the maneuver, and pull it back a little at those places where you might lose tension. On the hourglass you may have to pull down as you get to the top left corner. If the plane won't pull as hard as you want it to, you pull a little from your end.

My Time machine 40 had some line tension issues when it was new, most noticeable in the first and third loops of the clover and to some degree in the hourglass. I added some tipweight (don't know how I added, I started with 1.13 oz as the plane was built.) I actually have a teeny bit of clay stuck on the wingtip now for a very small adjustment. I moved the leadouts back about 3/16ths, maybe a quarter inch. This helped some too. But the plane really came alive when I went to 58' eyelet to eyelet lines from the 60's I started with. I've left the combination pretty much like that since then. I'm running an FP 40 retimed to run 4-2-4 with a revup 10x6 extra wide.
Warren, if you've got more questions you can look for me at Brodaks, I'll have the ugly blue Time Machine 40. Better yet, Tom Dixon will be there and probably suggest enough trim changes to make your head spin!

Line length is one adjustment in trimming that most people ignore. In our case we went to longer lines, but that is another story.

Your comment on moving the leadouts back is interesting, however. Since you experienced the difference in the first and third turns of the clover, it is not an inside verses outside thing. The first loop is an inside loop and the second is an outside loop, but both are above (mostly) 45 degrees. And if it helped the Hourglass as well (also outside, but, again, overhead) then it must be an overhead tension problem you were experiencing.

To improve overhead tension at the expense of a little straight and level (where we don't need as much) most will find moving the leadouts forward a little will help. Now you may have had them too far forward and lost tension all over.

Generally check tension in level flight and at about 45 degrees. If the tension at 45 degrees is less, move the leadouts forward (slightly) to see if it helps. Move them forward a bit at a time until the tension at 45 degrees and in level flight is about even. (And if you lose too much tension down below, you have moved them too far forward.) Do this after you have gotten the CG correct on the plane, lap times where you want them, and so on. All of these affect leadout location anyway.

It is best to do this on a relatively calm day so the effects of wind are minimized. But overhead, we have to remember, the effects of gravity are against us. So a little boost in rpm or power will help out up here (if our set up will allow this), as will a little hand movement at the right places.

Leonard Neumann

As Len said earlier if you loose tension above 45 it is a LO location and tip weight could help some. Diameter always helps but you have plenty of that for the plane you are flying. You can try this. Put a tiny little mark in pencil on the tip where the cg is currently located. Then while you are at the field and testing it out you will know when you are getting close and what to expect as you get close to cg or set them just a bit past on the front side just to get a good feel for this. Since you are going this alone it is a good idea to use marks and reference points on your plane go by. I have the Article by Paul W. about trimming with the chart. If you want it email me and I will send it on. I have read it myself countless times and always read it before I take a new one out. I would shoot for getting those LOs as close to the CG as possible.

There is one other point you made that has me thinking you have another small problem that must be corrected.

"One data point.....on the horizontal eight, I have much better line tension on the OUTSIDE loop compared to the inside loop portion, which is weak....I have to pull back on the handle. This seems to be in contradiction to the top two outside corners of the hourglass that are giving me a problem. This should be indicative of "something" but I don't know what."

This has to be fixed. I think it might be rolling on you just a bet. Excessive amount of yaw can cause this to so going after the LOs first is a real good idea. Also when you move LOs forward you can carry a little more tip weight. Dont go crazy with it though. Do one thing at a time. LOs forward then Tip Weight. Nevr both at once unless it wont even fly any of the pattern and you are just trying to get in the air.

About this roll. Next time you fly really watch the wing and see if it is rolling the wing tip up or down anywhere in the H8. Do them higher than normal so you dont have a mishap but really watch the wing. If it is rolling on you it can cause there to be more tension one way then the other. Really watch it in level flight and see if it flying straight. The wing has to be level.

Tweak the tips of that prop a LITTLE it helps alot. If you dont have a gauge dont try it. If you get it way out of pitch from one balde to the other it might fly terrible and run bad and all that. If you have no way to measure how much you tweak it then you are playing a really tough guessing game that will most likely lose.

LAST EDITED ON Jun-07-02 AT 08:12 AM (CST)

z

LAST EDITED ON Jun-07-02 AT 03:35 PM (CST)

The responses re line tension are very informative. I am currently flying an RSM Warburton "TONY"; weight of 47 ozs., and OS 40FP power (Lew Woolard). I had similar line tension problems. One of the additional (last) things I tried (and now use) was a 3 blade Bolly, 10.5 X 6.25 trimmed to 9.75. This helped in my case. I launch at 9400/9500 RPM.

Your thoughts, Leonard.

Thanks

Wally

P.S.: line length is 64'3", eyelet to eyelet. This combo gives me lots of time and air space to fly. (just my preferences)
wnb

Len,
You are right, I think the leadouts were a bit too far forward. Line tension did increase overall after the adjustment back. Tension is suprisingly constant whether down low or overhead now. I use the 58' over 60' mainly because my FP setup, for whatever reason, has a certain RPM it like to run at, and unless needled well off that point, it invaribly sets up into a droning four stroke after takeoff. Often the only discernable effect a needle adjustment has is a small change in fuel mileage while the sound and pull of the engine remains constant. At any rate, this mode of engine run is happiest pulling 58' of line, so thats where I leave it!

>LAST EDITED ON Jun-07-02
>AT 03:35 PM (CST)
>
>The responses re line tension are
>very informative. I am currently
>flying an RSM Warburton "TONY";
>weight of 47 ozs., and OS 40FP power
>(Lew Woolard). I had similar line
>tension problems. One of the
>additional (last) things I tried
>(and now use) was a 3 blade Bolly,
>10.5 X 6.25 trimmed to 9.75. This
>helped in my case. I launch
>at 9400/9500 RPM.
>
>Your thoughts, Leonard.
>
>Thanks
>
>Wally
>
>P.S.: line length is 64'3", eyelet
>to eyelet. This combo gives me lots
>of time and air space to fly.
>(just my preferences)
>wnb

Since you asked, OK. You have told me your line length. I would be curious to get your lap times as well. I like the idea of a little longer lines (such as you have) so long as you can get adequate tension and proper lap times. It does give you more space to work in. And, ironically, if the lap times remain the same, going to longer lines won't make the pattern take any longer, nor will it affect your reaction time all that much.

Now, on Lew's engine, Lew is a good guy and I trust his rework on his engines. But I don't know how he sets up the 40 FP as I have only seen and run his Fox engines. Generally speaking, when you go to a 3 blade prop, you take an inch off of the diameter compared to a 2-blade. So if you have 9 3/4 inch diameter with the 3-blade, it would be close to a 10 3/4 2-blade. I would personally want to go with a little more, but some like the smaller props, and if you are happy with it, that is what counts. You said this prop increased your line tension. I am curious as to what 2-blade prop you were using before you went to the three.

Dear Warren,

You have an extra hint here. There is most likely a trim problem, but the tip wt/leadouts may only be partly to blame. The rounds are the clue. More tension or better tracking inside vs. outside is probably a wings level ajustment. The kicker is the over head. EG. If you have better tension in the outside than inside, the plane needs an aileron ajustment. This will show the most in the overhead, easier to tell there. As a result of not wings level, the plane may be rolling with the top of the hourglass--where you cannot see the roll from the handle--or a not sealed flap would cause a similar roll.

So, if you can, have someone watch very critically for wings level upright and inverted, once that is ok, only then go for leadouts/tip wt ajustment. You have probably already made certain of this, but its an idea.

Warren,

A couple of important pieces of the puzzle are lacking.

What is the wing area? What is the weight (no guessing now!)? Are the hinge lines sealed?

Ted Fancher

>
>So, if you can, have someone
>watch very critically for wings
>level upright and inverted, once
>that is ok, only then
>go for leadouts/tip wt ajustment.
>You have probably already made
>certain of this, but its
>an idea.
>
>Dave

Tip up/down is not as easy to see as one may think. Get someone you trust, and make sure he/she fully understands what you need to know. Many people will just look to see if the wing is level to the ground. This may get you in the ballpark, but finer adjustments are made to make the wings straight with the lines.

Concerning the Hourglass, most people over turn the first corner. The center of the Hourglass needs to be dead downwind. With feet spread to shoulder’s width, the first turn should be done at your left toe. The first corner should turn the model so that a straight path takes it to your right shoulder. If the first corner is overturned, the climb will be too flat and will bleed off too much airspeed as it heads back into the wind to maintain good tension overhead (it will also take your intersection far above 45 degrees). This effect will be exaggerated as wind speed increases. Try to think “STAND IT UP” when doing the Hourglass. It will not only look better, but it will be easier to perform and will hold better tension at the top.

Curt

I’m not an Expert; I just pretend to be one on the Internet.

>Concerning the Hourglass, most people over
>turn the first corner.
>The center of the Hourglass
>needs to be dead downwind.
> With feet spread to
>shoulder’s width, the first turn
>should be done at your
>left toe. The first
>corner should turn the model
>so that a straight path
>takes it to your right
>shoulder. If the first
>corner is overturned, the climb
>will be too flat and
>will bleed off too much
>airspeed as it heads back
>into the wind to maintain
>good tension overhead (it will
>also take your intersection far
>above 45 degrees). This
>effect will be exaggerated as
>wind speed increases. Try
>to think “STAND IT UP”
>when doing the Hourglass.
>It will not only look
>better, but it will be
>easier to perform and will
>hold better tension at the
>top.
>
>Curt
>
>I’m not an Expert; I just
>pretend to be one on
>the Internet.

Curt..PERFECT.“STAND IT UP”

Scott(no viagra)Riese

LAST EDITED ON Jun-10-02 AT 03:03 PM (CST)

Sorry for the delay in responding.....it's been a hectic several days, trying to trim two different ships.

Thanks to all that posted....your suggestions have been noted.

>A couple of important pieces of
>the puzzle are lacking.
>
>What is the wing area?
>What is the weight (no
>guessing now!)? Are the
>hinge lines sealed?
>
>Ted Fancher

Ted....the answers to your questions:

wing area 526 in^2

weight 49 ounces (with 2 oz. of tip weight)

wing loading 13.2 oz./ft ^2

The weight is obviously highter than I would have liked (too much paint), but the Time Machine has a fat wing (2 1/4" thick at the root), and seems to handle the extra weight well (the next one WILL be lighter).

re: sealed hinge lines. I'm going to get reprimanded here, for sure (may even have to stay after class). I did seal the hinge lines during construction, but even though I was very careful about doing so, there was an increased stiffness in the control system that was not tolerable, so I removed the tape. The control system itself is very free (balljoints), but I got carried away trying to keep the gaps tight when mounting the ailerons and elevators and have essentially a zero gap. With the tape off, I may be able to compress some of the wood, and then re-tape.

[photo not recovered: 3d0513bb794120a7.jpg]

Things that I have tried:

By clamping a couple pieces of straight balsa to the flaps, I could see that the left flap was up. I tweeked the flaps until they were level. Results...now I lost line tension in the outsides as well.

Because the engine was new, (it was properly broken in), and because it had different running characteristics (i.e. high rpm, low pitch), I chose to put back in the OS40FP that was originally in the plane, and that I had a lot of running experience with. It runs in a lower rpm range with a 5" pitch prop.

I got smart, and went directly "to the horse's mouth" and put in a call to Tom Dixon, the designer. He was very helpful, and had several very important suggestions. First of all, and perhaps the most important element, is that the Time Machine has equal span wing panels, and requres 2 - 2 1/4 ounces of tip weight!!!! I had been running 1 1/4 oz. and worked it up to a full 2.0 oz. Also Tom wanted about 2 degress of nose down attitude when suspended by the leadouts. I had less than that, so the leadout guide went back to 1" behind the CG.

The result are that the plane is much improved and is now flyable. In hindsight, I think the 4" pitched motor was being run too slowly (lack of familiarity). The increased tip weight was very significant, and the more rearward leadouts helped.

I can now get through the hourglass, though I'm sure there are things that can stand improvement. Tom said he would help me at Brodak's.

It's very frustrating not to have an experienced viewer watching from outside the circle. Flying Intermediate, and having only learned the full pattern 6 months ago, it is impossible for me to fly the difficult manuevers and observe what the plane is doing wrong. I'm sure it will take a lot of experience to be able to do that.

Thanks for your help, and we'll see y'all at Brodak's.

Cheers,

Curt is right. Flying the thing at wrong angles is one of the main reasons people complain about the tension and flight characteristics during that particular maneuver. The entrance angle should be the same as your triangle entrance. This is KEY! Miss the entrance and the recovery is tough. Pay close attention to this. If you are doing the same corner and it(Hglass) is real flat and spread out this will tell you that your triangles are laid over to far also. Kind of a two birds with one stone type thing. Any way One of the most common errors is not flying the plane high enough before making the second turn. If you turn to soon then you will loose tension right away. This will cause your model to be headed behind you at an angle that is going to make the third turn very difficult at best. Make sure the plane goes all the way up to the top of the circle then snap that turn hard. Now the plane will fly straight across the top of the circle just like a wing over going cross wind. (I like to think of it flying across my eyebrows straight across my face) Then snap it again and let it just fall at a slight angle on the way down. Now the pull out is much easier and the final corner is not so compressed. Yes STAND IT UP! The top leg actually looks short to me when I am getting my best scores. This is how Know I am flying it pretty good. When it looks straight up and the top leg looks short from my point of view. When the top leg is long you will get your intersection below the 45 point when it is to short you will be above the 45 point. I hope these tips help. They really helped me out alot.

DMoon

PS Not an expert either, just pretending to be.

>D Moon wrote:
>...Make
>sure the plane goes all
>the way up to the
>top of the circle then
>snap that turn hard...

You should not need to hit the second corner hard at all. The wind should help the model turn the second corner to the point of being one of the "least input required" points of the pattern. You can hit it hard, but you will gain nothing. It is easy to get carried away with the corners on the Hourglass. If you want to concentrate on one corner, make it the last one (David Fitzgerald does the fourth corner very well). The judges see the fourth corner much better than the second one.

Movable rudders add line tension to outside maneuvers such as the top of the hourglass and vertical eight. As for the equal span panels, I published that idea in the Sea Fury article with the warning that a great deal of tipweight would be required to compensate for the absence of asymmetry. The Sea Fury required 3 ozs. I suggest adding tipweight until the airplane "hinges", then back off just a little. It could take 2 ox or more but tipweight is pure line tension up to the point of "hinging". The whole subject of methods of making line tension was covered in the Sea Fury article, the Mustuny article and the Mustang article Evolution of a "Thouroughbred".
Al

LAST EDITED ON Jun-10-02 AT 11:14 PM (CST)

> The whole subject of
>methods of making line tension
>was covered in the Sea
>Fury article, the Mustuny article
>and the Mustang article Evolution
>of a "Thouroughbred".
>Al

Al;

Tried emailing your earlier, but to no avail - your email was bounced back. At the risk of public censure, I will post the gist of the message here.

Many of the readers have not had the opportunity to read the Mustunt Series or the Sea Fury article your published almost a quarter century ago. The Mustunt Series and the Sea Fury articles were great pieces.

If assistance was provided on the technical end, what would you say to the possibility of making these articles available to the masses in digital format? I could talk to Larry Cunningham, and possibly distribute through the PAMPA web site. If that option folds, I have a web/ftp site that could be used as well.

Just an idea. If interested, email me at [email protected]

Reprints of the Mustunt article would be good. I was six years old when the original article ran, so I didn't save it....(!)

I posted a summary of my changes and results in a reply to Ted's post #16.

It tended to disappear in the center of the thread, so if you missed it, and would like to read the update, please refer to post # 17.

Thanks for all your help.

Cheers,

Just a couple of comments:

You should be able to view the alignment of the flaps pretty well just by looking very closely from the back. Note if they are absolutely even--that when one is centered, the other is centered, but that there are no warps, either. This you can't tell by simply sighting or measuring at one point. Then make sure that the elevators are at neutral when the flaps are neutral. Sometimes when we "tweak" one or the other, we end up with a slight up or down setting.

A queston for you. When you say the leadouts are an inch behind the CG, is this the center of the leadouts? You would probably be rather close with that, but some, here, are evidently measuring from the front leadout only. I had to ask.

Don't be afraid to add tip weight. Add until you get a noticeable "dip" in a hard corner. Then you either have gone too far with the tip weight, or the leadouts need adjusting. If you are starting at an inch back, I would work on tip weight first, then adjust (very small movements at a time) the leadout position.

In building, you need to make sure the fuselage is absolutely square with the wing and that the elevator hing line is absolutely square with the wing hingline. Measure, measure, measure. It is mostly too late for this now, but a crooked plane will never get trimmed properly.

What are your lap times? If you were flying the original engine too slow, were your lap times too slow, or just not getting proper power out of the engine. The engine needs to be set for its best, and then the proper propeller put on to get proper lap time. A beautiful "sounding" engine with improper lap times will fly lousy. A plane set for proper lap times, but where the engine is not at its best still will lack something somewhere. Usually what it lacks is tension and drive, but you can also experience the dreaded whip up in the wind and speed up going down hill as well.

These are all things you can learn with experience, but, you are correct, it helps immensely if you have a flying partner who can aid you in your journey.

Len,

>A queston for you. When
>you say the leadouts are
>an inch behind the CG,
>is this the center of
>the leadouts? You would
>probably be rather close with
>that, but some, here, are
>evidently measuring from the front
>leadout only. I had
>to ask.

Yes, I always reference the average or center of the leadouts.

>Don't be afraid to add tip
>weight. Add until you
>get a noticeable "dip" in
>a hard corner. Then
>you either have gone too
>far with the tip weight,
>or the leadouts need adjusting.

The plans for the Time Machine 40 say "Start with 1 ounce of tip weight". I had gone up to 1 1/4 oz, and thought that I was probably OK. But after talking to Tom Dixon, and he said that design usuallys ends up at 2-2 1/4 oz, I realized that I was way too low in tip weight. I'm currently at 2.0 oz, and tension is much improved. A good lesson learned.

It "smarts" to use your good 4 lb. balsa during construction, and then add 2 oz. of dead weight when you are done, but it's a necessary evil, especially with equal span wings.

>What are your lap times?
>If you were flying the
>original engine too slow, were
>your lap times too slow,
>or just not getting proper
>power out of the engine.

I don't remember my lap times with the original Smith OS40FP, but I never try to fly any slower than 5.2 seconds per lap, and will accept down to 4.8 s/l for the secure line tension that speed offers.

> The engine needs to
>be set for its best,
>and then the proper propeller
>put on to get proper
>lap time.

Randy Smith explained that principle to me, and it's an important concept. I have to work at it to put it into practice.

Cheers,

>The plans for the Time Machine
>40 say "Start with 1
>ounce of tip weight".
>I had gone up to
>1 1/4 oz, and thought
>that I was probably OK.
> But after talking
>to Tom Dixon, and he
>said that design usuallys ends
>up at 2-2 1/4 oz,
>I realized that I was
>way too low in tip
>weight. I'm currently
>at 2.0 oz, and tension
>is much improved. A
>good lesson learned.

Isn't this a Tom Dixon design? If so he should note the plans that starting at 1 oz is just a reference point but oprtimal is going to be around 2oz or 2.25oz. Why would the plans say 1 oz when you really need 2.25? Seems like alot of people would have trouble trimming this plane.

I would have the same feelings as you did. After adding a 1/4 and getting nothing I would have thought there was something out of alignment or rudder was wrong or something. Starting Tip Weight amount is pretty important. I guess you have to be ready try it all. Only trouble is when the plans call for 1oz you might end up with TW box that is to small to hold 2oz.

Doug, can you imagine the fit Bear would have if he had to put 2 ounces in the tip of his plane? LOL

Bob,
I feel those articles comtained a lot of good information and original ideas which were new then but common now. I think it would be nice if the information were made easily available. Many people do appreciate the information contained in the Mustunt, Sea Fury and Mustang articles. The subject of this thread was adequately covered in the 1978 "Evolution of a Throughbred" article which Tom reprinted in the Mar/Apr 2000 Stunt News. Equal span wings were addressed for the first time, in 1977, as to trimming, tip weight and line tension in both the Sea Fury and Mustunt articles. In fact, these problems are covered again and again today in Stunt News and here. The art of stunt is learned through reading and experimentation. We shouldn't rely on the readily available web solutions and expect correct "tailored" responses. Maybe "trimming" is becomming an unappreciated art. We buy kits and expect them to fly well if built straight and adequately powered. We expect he plans to specify the amount of tipweigh required to make the airplane fly well. One of the first trimming exercises one should do with a new airplane is to add tipweight until the airplane "hinges". Tip weight is line tension. One should not arbitrarily decide that 1 oz or 1 1/4 oz is enough. You will find "enough" when the airplane tells you that "now, we have enough". Preconception is the ememy of experimentation. Trimming is a learning process gained through experimentation. Anyway, as for making the Mustunt and Sea Fury articles available, I'm all for it but making them accessible dosen't mean that enough modelers would access them to make the effort worthwhile. If they didn't read "Evolution" in their Stunt News, they won't spend any effort to research Mustunt and Sea Fury.
Al

LAST EDITED ON Jun-12-02 AT 05:29 AM (CST)

>Bob,

>process gained through experimentation.
>Anyway, as for making the
>Mustunt and Sea Fury articles
>available, I'm all for it
>but making them accessible dosen't
>mean that enough modelers would
>access them to make the
>effort worthwhile. If they
>didn't read "Evolution" in their
>Stunt News, they won't spend
>any effort to research Mustunt
>and Sea Fury.
>Al

Al;

I agree with much of this.

But....

Consider a couple of things. Firstly, your span of knowledge literally bridges two or three "generations" of Stunt development. For you, this is "common" knowledge. To others it might be a revelation. For those who didn't have the chance to read what you came up with in the early-mid-late 1970s, it would be fascinating reading. Most articles were "Do this, because I am telling you to do it..." Yours normally had a good development behind your theories and and a defensible rationale. I don't always agree with what you say, but I respect the man who tests his theories and has some type of practical experience to stand by them, and defend what he puts forward. I think most other folks are the same.

Regardless, this is not an attempt to stroke anyone's ego. Simply stated, I always thought your Mustunt articles and your Seafury article were classics in the stunt world. They combined theory, practical experience, and detailed analysis into a package that is very much useful today. I very simply consider them to be some of the cornerstone documents on design, trim, and theory. The pity is that most folks under the age of 40 (yep Al, it's true. We are getting some age on us) didn't have the chance to read these articles when published.

So, the offer is there. Personally, I think the stunt community as a whole would benefit from having easy access to your Mustunt and Seafury articles. Easy access neither negates nor minimizes the effect these articles might have. And, the large effort for the articles is already done. Scanning them into the digital domain is much simpler than all the work you went through to capture the knowledge.

The bottom line is that you did good work, Al. Magnificent work. That work was back by undeniable and irrefutable results. Realize that you have forgotten more about this hobby/sport/obsession than many of us know. Many of the newer CL builders and flyers don't have easy access to your work, nor do they even know about it. I would ask that you don't minimize this work by taking into account what people might not do with it because of web access. Just think of what they might do if they HAVE easy access to it from a web site....

I will say no more publicly of this. If I can be of assistance, please contact me at [email protected] . I hope that you do - I think much good will come from it.

Tight lines, Al.

I'll spend the effort. Hmm, I bet I know where I could borrow a copy locally.

Al: I subscribe very much to what you wrote. We have tried equal panel wings and assymetrical wings, and equal panels won out. I was talking to Jim Hunt last week and he said they had tried both on a similar stunter and liked assymetrical better, but I think sometimes people didn't get them trimmed properly which is why they made the judgment of one over the other. Yes, you need more tip weight for equal panels. But, yes, you get more tension, especially overhead. As I like to repeatedly point out, part of what we are doing is balancing out the weight of the lines. If you balance this with assymetry (trying to get more lift on the inboard wing) then as soon as you aim the plane straight up, as in a wingover, the extra lift is gone, but the line weight (and now drag of both the lines AND the larger inboard wing) is pulling the plane in. And then if you have a bigger inboard flap (really a bad idea) you "wiggle-waggle" yourself into such a corner that you need to drop so much tip weight that your pull really goes out the window.

And big props, Rabe rudder--we have used the Rabe rudder before, and then not used it. But Matt decided to put an adjustable rudder on his new ship with the option of making it into the Rabe configuration. He first flew and trimmed the plane with the rudder in a fixed, non-offset position. After trimming it as best he could in a minimal numnber of flights, he decided to try the Rabe configuration. Just adding the "wiggle" to the rudder, and with no attempt to optimize it, he noticed a definite improvement in the overhead, hourglass, etc. So, it stays. Of course, he is running a 13.5 inch three-blade prop (and intends to go to try a 14 inch). Smaller props may not show as much improvement (or need, for that matter).

But, I would be glad to host the articles, or portions of them, on my web site, if someone wants to put them in order. Bob helped me put up the forum (and teach me a little about pearl scripts), so if he, or howard, or anyone wants to get these in a form that we can easily put on the web site, I will be glad to do so.

Yes I have seen this fit first hand. That plane he had at last years nats had a very long span 63" and only 5/8" offset. A pretty high aspect ratio also. He had to go with alot more than he is used to and it made him crazy when trimming it out because the plane was so lite weight then he has to go and put 2oz in it. He made comments about that for days.

Leonard,

You make a good point about equal panel wings and the weight when the plane is turned straight up for the wing over and the lines and drag.

My question is if you build a plane with a deeper fuse like a big Nobler or an Infinity will the fuse help with the lifting when the plane is turned up and flying over head as opposed to say a Saturn type skinny fuse. I have built both types and the deeper one always seems to fly better overhead and above 45 degrees.

Am I crazy or is there something to this?

Doug,

GMA took some kind of engineering in his college days, it might have been aeronautical? George was no dummy and when you come to the Nats you can watch Curtis fly the Jubilee - it's based on some GMA aeronautical ideas. And I must say it does corners as hard as any other plane I have seen fly, if Curtis wants to step on the handle hammer.

LAST EDITED ON Jun-12-02 AT 10:07 AM (CST)

>put them in order.
>Bob helped me put up
>the forum (and teach me
>a little about pearl scripts),
>so if he, or howard,
>or anyone wants to get
>these in a form that
>we can easily put on
>the web site, I will
>be glad to do so.
>

Leonard;

OK, I said earlier I would not comment on this again. But, I feel your comment deserve mention and a little more ...

Firstly, you ARE a generous man. Again my thanks for making the system and providing for the bandwidth that makes this forum available. If anything comes of what I am proposing, I will be glad to donate my limited technical skills to assist.

There are some excellant articles written that cover the bases for theory, design, construction, finishing, trimming, engines/tanks/exhausts/fuel systems, and pattern accuracy. In my simplistic way of thinking, making these available through the digital domain can only help this hobby/sport/obsession. While I respect the idea that people need to get out and practice, the fact is that many of the mistakes that are made could have been prevented with a little knowledge.

Perhaps we should take the time to identify some of these cornerstone articles. Once identified, we could contact the authors and publishers and request permission to make them available through the digital domain. We can then scan, edit, and upload to a board.

I am a little curious as to why we haven't seen more of this with the PAMPA site. Larry has done a great job with his BBP series, but I don't see some of the top folks in this hobby/sport/obsession coming forward with their publications and writings and making it available to the beginning or average flyer. When you consider the low density of CL flyers as a percentage of the modeling community, the fact is that many potential new CL flyers don't have someone around to assist them. I have to wonder how many new flyers we lose each year because they built a Ringmaster or a Skyray or a Twister, and pranged it because they don't know how to build properly, or they don't know how to trim, or they don't know how to set up an engine or break it in properly, or ... I think everyone gets the point. After one or two of those crashes, the person is discouraged beyond recovery, and goes off to another hobby.

Having an experienced modeler near by is always a great help. But, if you don't have that, what do you do? You can either figure it out the hard way (brute force and ignornace will prevail, but it is costly), or try to find another source of knowledge and wisdom. The digital domain can be a great medium to making some critical information easily available. In my limited way of thinking we should have a virtual CL library covering many topics available for easy access, and the organization carrying the guidon should be PAMPA (Boy, am I going to get into trouble for that one, but its just my opinion). Frankly, until Larry Cunningham used his initiative and posted his fine BBP series, there were almost no technical HOW-TOs available on CL out there, save for Leonard's site and Heman Lee's site. If I missed any others, my apologies. Heck, some of Leonard's links for HOW-TOs are to RC boards. Nothing wrong with that, but it points to a dearth of CL knowledge and wisdom unless one wants to search the messagebases for various board. Information is only useful if it is available and organized. For the new and intermediate flyer, I believe it would be helpful to have some of the cornerstone writings available in an organized manner from a single site. I would personally like that site to be under the PAMPA colors, but if that is not possible, then a site such as Leonard's is a fine solution.

So, that aside, I am going to put a plug in for some articles that I would like to see made available:

Al Rabe's Mustunt Series
Al Rabe's Seafury article
Paul Walker's Trim Chart
Phil Cartier's CL Fuel Tank Series
Ted Fancher's Doctor Article
Ted Fancher's "Fancher Twister" series
George Aldrich's Series on Designing your own stunt ship.

This is just a start. I would love to hear of other recommendations. And, perhaps it is time for a new thread.

Bob,

1. The Olympic Article by Bob Gialdini
2. The 1951 Nobler Article by George Aldrich
3. The Control Line Aerodynamics made Painless Articles By Bill Netzband.
4. The "Stunt a New Tune" Article by Bob Hunt
5. The Impact Article by Paul Walker in it's entirity, not just the trimming chart.
6. The "So you want to be a Champion" Article by Ted Fancher.
7. The "Skylark" article by Ed Southwick
8. The Articles by Joe Adamusko in Stunt News on Finishing.
9. The Saturn article by Bob Hunt.

That's just some of the ones in addition to those you have already named that I can think of Bob.

Good luck on the quest!

Jim Pollock

Doug,
yes, it is easy to run out of room for tipweight, if tipweight is your first trim effort (and it should be). I made strong arguments for equal span panels in my Sea Fury and Mustunt articles. Believing this was optimum, I built both Sea Furies and all of the Mustunts with no asymmetry. Like Bob though, I did hate to carry so much tip weight, so, in the design of my molded Mustangs, I explained my reasoning for opting for a different configuration. To lessen the tip weight required for the new Mustang (Snaggletooth) I tried to reach a better, lighter balance between asymmetry and tip weight. I used 1/2" of asymmetry to reduce tip weight required and tried to maintain as much of the aerodynamic characteristics of equal panels as possible by using flaps of equal area. While the inboard flap is longer the outboard flap is wider at the tip by about 1/8". This is all in the reprint and oiginal "Evolution" printed in 1978. Did anybody else use this configuration then? I don't think so, but is is fairly common now and is the configuration I used on the Millennium and BBQB Bearcat. These are big airplanes with a design weight of 65 -70 ozs. Comparing wing area and span with other modern aricraft wouldn mean much as my airplanes are designed to lift more weight/area than is common. I use big, stiff flaps and move them much farther in maneuvering than usual. I build in 1 1/2" ozs of tip eight and have room for much more removeable. I still wind up with some removable installed. I still trim for maximum line tension even though the BBQB is giving me "Tennis Elbow". It must be in the B-17 class, but it's there when the wind blows and the 4 stroke nicely resists build up in down wind maneuvers. It is a very competitive bird. It must be old age, I do tend to run on.
Al

I'll supply graphics if any are needed to supplement the articles.

> It must be in
>the B-17 class, but it's
>there when the wind blows
>and the 4 stroke nicely
>resists build up in down
>wind maneuvers.

Yours may pull hard, but I would debate the "B-17 class" part. That sucker was something else.

Brett
My sucker is something else too.
Al

>Leonard,
>
>You make a good point about
>equal panel wings and the
>weight when the plane is
>turned straight up for the
>wing over and the lines
>and drag.
>
>My question is if you build
>a plane with a deeper
>fuse like a big Nobler
>or an Infinity will the
>fuse help with the lifting
>when the plane is turned
>up and flying over head
>as opposed to say a
>Saturn type skinny fuse.
>I have built both types
>and the deeper one always
>seems to fly better overhead
>and above 45 degrees.
>
>Am I crazy or is there
>something to this?
>

I don't think that "lift" is the issue. I think the deep fuse helps keep the yaw angle and the yaw rate small, and getting rid of yaw (either direction) helps the overhead tension. Outboard yaw is well known to be an overhead tension killer.

I went out of my way to put in a lot of lateral area, and it's hard to do it without making it look like a Nobler.

FUBAR,

Can you duplicate to nomographs that abound in Bill Netzbands
articles?

Wouldn't the built up fuselage of a stunter act as a lifting body when the plane is in knife edge flight-like the wingover, etc? (actually I imagine it generates lift-or outforce I suppose you could say, everywhere in the hemisphere we fly in) That being the case I would think the Nobler type fuselage would be superior to the Saturn type fuse. (more lifting area) And it might explain why built ups seem to have better line tension than profiles in many cases-the profile has an inferior shape in terms of being a plank, and has an engine and tank sticking out to disturb the airflo over the fuse. Everyone can agree that you don't need an airfoil so to speak for lift-hence flat slab wings, the ill fated lifting bodies like the Six Million Dollar Man flew, and hapless stock cars swooping into the air when they spin out. So the curvaceous fuselage of a built up stunter could be a contributer to outforce and line tension throughout the flight envelope.
just curious....