Scaling Down (model of a model)

LAST EDITED ON Jul-27-03 AT 01:08 AM (CDT)
 
I've noticed the top guns in stunt have, what I would consider, really big airplanes. Do big airplanes fly better?

I've been sport flying Ringmaster/Flightstreak/Buster type planes and, I want something better for beginner class contest flying. A friend suggested the Banshee, Twister or a profile Cardinal with a Brodak .40 engine. That's about $200 to upgrade my stunt program. That's ok with me but, I always want to try something different.

With the work space, storage space and collection of engines I have, I'm a little resistant to building a bigger plane. My thought was to scale down a good flying plane (probably the Cardinal) to a smaller size. The plane would be scaled around a 400 Square inch wing area.

Would it fly better by design or, does size really matter??

Thanks,
Giffy

P.S. If size does matter, what about going the other way? A 550 square inch PDQ Flying Clown? LOL

LAST EDITED ON Jul-27-03 AT 03:35 AM (CDT)
 
>I've noticed the top guns in stunt have, what I would
>consider, really big airplanes. Do big airplanes fly better?
>I've been sport flying Ringmaster/Flightstreak/Buster type
>planes and, I want something better for beginner class
>contest flying. A friend suggested the Banshee, Twister or a
>profile Cardinal with a Brodak .40 engine. That's about $200
>to upgrade my stunt program. That's ok with me but, I always
>want to try something different.
>With the work space, storage space and collection of engines
>I have, I'm a little resistant to building a bigger plane.
>My thought was to scale down a good flying plane (probably
>the Cardinal) to a smaller size. The plane would be scaled
>around a 400 Square inch wing area.
>Would it fly better by design or, does size really matter??
>Thanks,
>Giffy
>P.S. If size does matter, what about going the other way? A
>550 square inch PDQ Flying Clown? LOL

Giffy... If you are going to fly beginner stunt or intermediate even, you won't have to spend much money at all...USE WHAT YA GOT!!! I'm really serious about this...your Flitestreak can take you into Advanced Stunt...maximize your resources....Practice as often as you are able; trim that Streak to it's potential. Then after wearing it out or crashing it to total destruction, buy another kit or the Flitestreak ARF; and have another go at it. The Flitestreak, when properly trimmed actually flys better than the "Upgrade Choices" You've previously named..
When you get into the high 400's or low 500's ...build a full on Stunt competition machine...you will have learned a bit by then. Best of Luck;
Tony G.

A Flitestreak is an adequate airplane up through Advanced. I had a lot of fun with a Jr. Flitestreak and TD 09. Flew it in Classic and Advanced and even got a couple of 3rd place trophies. If you want a flapped airplane, a stock Twister with a Fox stunt 35 can be made to fly very well. Given that the motor runs right, the airplane is straight and trimmed out right, there are an amazing number of airplanes that will fly better than I can fly them!

Bob Hunt makes the point that smaller airplanes can be made to fly very well, and may be more optimum. (Hunt is a World Champion, he might be worth listening to! )

At the same time, realize that there are good reasons why the top dog airplanes look the way they do. If some competitive advantage would be gained by making them smaller, you can bet it would be so.

Personally, I defy anyone to watch a properly set up Impact fly and tell me how a Streak or Twister might work just as well.

[photo not recovered: 3e69bb3870f12ad5.jpg]

"Ignorance is a voluntary misfortune." -Nicholas Ling

>Bob Hunt makes the point that smaller airplanes can be made
>to fly very well, and may be more optimum. (Hunt is a World
>Champion, he might be worth listening to! )
>
>At the same time, realize that there are good reasons why
>the top dog airplanes look the way they do. If some
>competitive advantage would be gained by making them
>smaller, you can bet it would be so.
>

And it might be so, in the not-so-distant future....

LAST EDITED ON Jul-27-03 AT 12:10 PM (CDT)
 
Small models in “not-so-distant fure”?

Is my Max with 620sqin large? (3 pieces in final in Sebnitz)

Or did Todd Lee fly large model in Sebnitz?

I think it is slowly but safely getting true. And I think this is why new FAI rules allowing bigger engines do not change existing models, or does not start any power battle.

Here is my Middle flying VERY well with OS 25 LA. Only the engine run prevents of serious usage. May be later with pipe

http://www.netax.sk/hexoft/stunt/the_middle.htm

>Small models in “not-so-distant fure”?
>
>Is my Max with 620sqin large? (3 pieces in final in Sebnitz)
>
>
>Or did Todd Lee fly large model in Sebnitz?

Todd's is about 700 square inches, so, yes, it's definitely on the large side. 620 is still larger than I have in mind. Most of the California models for the last 20 years or so have been in the range of about 620-660, which fit's my definition of large, is a bit on the small side compared to most, and significantly smaller than the types of models Werewage has been flying, and to which Bob Hunt was referring. He was surprised last year when we started talking about "smaller models" and learned that mine is only about 655, and Ted's is pretty similar or even a touch smaller.

When I said small, I was talking 520-530, and he was talking 630-640 - same as ours were already. Of course, we also differed greatly on what they should weigh. I figured 58-62 for 640, and he was talking more like mid-40's.

I can state categorically that nobody should try to build an Infinity to 48 oz - if one does so, one is on one's own, because the airplane is designed to be about 63-65 oz. and very stiff.

>>>Todd's is about 700 square inches, so, yes, it's definitely on the large side.<<<
??? I am surprised. I had better measure it . It can be that the colors make it smaller than those white sport types.

But I understand what you mean. The Middle from my previous message is only 450sqin. It flies really well and givig feel of very low, but constant line tension everywhere, everytime (and far more than pattern needs). Surprising is also that is gives feeling there is lot of time between corners. Even it flies only on 17m long lines at 4.9s per lap, so reality is different - angular speed is much higher than larger model. … I think I will give him another chance end of sesone I must find more reliable setup for that LA engine.

However I wonder if judges will take it seriously

Just for fun ( in the „small airplane „ area ) –
Out of curiosity I wanted to know how small an airplane can do the pattern without making a fool of the pilot. I think a 15 size engine is about as far as you can go. My little GIGOLO flies surprisingly well, and I’ve even flown it in competition ( when I already had two good flights and did not depend on the third flight !). Area is about 325 sq inch, span 42 inch, weight about 700 gramm ( German saying: he who wants to be beautiful has to suffer !). Engine is an old OS15, on full power. I fly it on 17 meters 012 lines. Alas, because of the weight I cannot fly slower than 4,8 sec/lap. And in high wind - forget it. But it’s so much fun !
claus

>>>My little GIGOLO flies surprisingly well<<<
Yes it does, I saw it. I think so small models can really fly very well. I think problem of small models is they are built by beginners. Small, well-done and properly designed model do not have any serious limitations. Here is my small ugly "beginner like" (white) model and same design with different cut (yellow).

>>>and I’ve even flown it in competition ( when I already had two good flights and did not depend on the third flight !).<<<
This is what I am curious about. Can (or does) judges take such model seriously??? When we spoke about new FAI rules I heard several times “bigger model is scored better”. I do not know if it is really so if I compare usual dimensions, but I afraid that such really small toy will not attract serious concentration of jury … am I wrong?

>This is what I am curious about. Can (or does) judges take
>such model seriously??? When we spoke about new FAI rules I
>heard several times “bigger model is scored better”. I do
>not know if it is really so if I compare usual dimensions,
>but I afraid that such really small toy will not attract
>serious concentration of jury … am I wrong?

This is the million-dollar question. I woudn't be all that concerned at the US Nationals, but it's really hard to say at any other contest. I suspect that if somone "of note" shows up with a smaller airplane, in a situation where it is obvious it's a serious effort and not a 'stunt' or backup model, it will be OK. And you darn well better fly it very well.

When I build mine, I might wear a T-Shirt with 'THIS IS NOT A JOKE' on the back!

>I've noticed the top guns in stunt have, what I would
>consider, really big airplanes. Do big airplanes fly better?

Open question, I think. Read the JUNAR article for Bill Werewage's comments on the topic.

>I've been sport flying Ringmaster/Flightstreak/Buster type
>planes and, I want something better for beginner class
>contest flying. A friend suggested the Banshee, Twister or a
>profile Cardinal with a Brodak .40 engine. That's about $200
>to upgrade my stunt program. That's ok with me but, I always
>want to try something different.

A Fancherized Twister with a 20 or 25FP has the capability to fly at least as well as any of these, and I would guess you could put it together for about $125. Of course, the key to making any airplane fly well is the trim and power, not so much the design. Although, the Ringmaster, and even more so, the Buster, are *very limited* in their capability. The Flitesteak is a lot better, but the performance of any of them is dependent on the engine/prop combination.

>With the work space, storage space and collection of engines
>I have, I'm a little resistant to building a bigger plane.
>My thought was to scale down a good flying plane (probably
>the Cardinal) to a smaller size. The plane would be scaled
>around a 400 Square inch wing area.

You probably don't want to simply scale it down 1:1. I have been thinking about this topic a lot lately, and and I suspect that this will not result in the same performance. I'm not entirely sure, but I would scale down the wing to whatever size you want, but probably not scale down the tail moment as much, and maybe set the tail volume coefficient even higher on the smaller models.

The problem with a direct scale is that some things don't scale 1:1. The engine doesn't get proportionally lighter, and the maximum pitch rate (as limited by the tail tangential velocity) doesn't scale at all - its the same for a given tail moment and angular control angular deflections). I'm not sure at all I have thought through all the different factors, so I can't give you a definitive list, but

Of course, people have been doing this scaling up and down without considering this sort of factor for years, so you'll get something that will probably work, if not be optimal.

What I would suggest is to pick a known design that's already the size you want. I would also not recommend going much smaller than about 450 square inches, because there aren't many good available engines smaller than a 15, so if you get too small, you can easily wind up with too much power to handle. And of course, I strongly suggest that you use a modern engine that spins a low-pitched prop at relatively high RPM. This will make far, far more difference than any minor design or scaling tweaks you could ever make.

Hey, Giffey,

I'm going to comment because I have had some experience with what you are suggesting. Mr. Southwick gave me a set of plans for the original Skylark at VSC 13. I am fortunate to have a friend who has access to a BIG copy machine which will scale drawings to whatever percentage you want. While I was having the full size drawings duplicated to use as building plans, I asked him to make a set of 80% drawings. This gave the "Baby Lark" a wingspan of 42". I also happened to own an OS .20 (CL version) engine. When the plane was completed it wieghed 26 oz. 52' lines it flys very well but won't take any wind at all. I fly it in 0-5 and it will do a very credible pattern. HOWEVER, I don't recommend it for competition because of the fact that contests are always scheduled for windy days.

The thread so far has given you some very good advice. Flight Streak is a VERY good plane and will take you a long way but building the smaller (maybe not as small as the Baby Lark) versions of proven designs can be a lot of fun and certainly get the guys attention on the field. Go for it for fun but if you are wanting to step up to plate then heed the advice previously given.

If you are intent on building new airplanes, there are a couple of kits for full fuselage airplanes in the 400 sq in size range. Brodak kits the "Fancy Pants" and Larry Richards does a great kit of the "Little Thunderbird". The little T-Bird is a sort of downscale of the original Palmer Thunderbird.
Steve

John, I would really like to see a set of those "Baby Skylark" plans some time.

Bigiron

This smaller model logic may just lead everybody right back to the Nobler (!) (or T Fancher's Chizzler?)

The timing of this concept works for me. If I ever get booted to expert, maybe I won't get laughed off the circle when I walk out with my little Gieseke Nobler......

Steve - trust me, no one will laugh at that Nobler, especially after they see how well you fly it. Both Dan and I were quite impressed with your performance in that absurd wind on Sunday. The real kicker is the power - a STOCK fox .35. I have never seen one run better. I guess when a Fox is on, it's really on! I should dig through mine and hopefully find one that runs as well.
Bob Z

"The real kicker is the power - a STOCK fox .35. I have never seen one run better. I guess when a Fox is on, it's really on! I should dig through mine and hopefully find one that runs as well.
Bob Z"

Bob. Thanks for the kind words. While sitting in traffic on the beltway Sunday night, the thought did occur to me that there is something noteworthy about that Fox in the yellow Nobler. A number of people have asserted on this board that Fox test runs each new engine, and the best runners get stashed in a box to send to people dealing directly with Fox on repairs and trade ins. The motor in the Nobler is one of those-it was sent to me by Fox when they determined the old clunker I sent them for repair was non-fixable. So maybe there is something to that story about the really good ones being hoarded by Fox. I certainly didn't do anything else to the motor. If you don't find any with heroic power in your personal stash at home, maybe pick out the worst one and see if you can trade it in for a better example from the factory. I think Fox charges half price on the 35 if you trade in a clunker, which makes it cheaper than buying from Tower, etc.
It was too bad the winds precluded you flying the .26 powered Nobler. Having seen it fly with the Fox at Brodaks, it would have been easy for me to see how the stroker stacked up in the same airframe. Now somebody needs to come up with a nano sized 4S so you guys can really terrorize the Musciano contest!

Steve - interesting how the theme of the thread changes with the various posts. Anyhow, I've flown the Nobler with the SAITO .30 and the Surpass .26. It flew like a dream with the .30 - then the engine failed and I sent it back. Since the mounts are identical, I decided to try the OS - definitely lacking the power needed. It's OK in the calm but not too happy when the breeze shows up. I have a new SAITO .40 that may wind up in the Nobler if it fits without a lot of hacking - we'll see.
Bob Z

Bob, I tried that small Saito too. I did not get enough time to play more with the model, but at present time I did not get reliable run yet. I used 10x4 prop with orrig. R/C carb wide open with 10% nitro. The problem was, that the needle setting was one click more too rich, one click less too lean. I do not know where i do the mistake ...

Igor - I have used two SAITO .30s. The first is in my Little Cherokee and has performad flawlessly since I started flying it. It has the stock carb and at well over 100 flights, I have not even changed the plug. I use 22% (50/50) , 5% nitro fuel and a Master Airscrew 9 1/2-6. I used the second one in my Nobler and was a bit disappointed. I wanted to test it in the Nobler becauase I'm building an Argus for it and I figured that until the Argus was ready, I could put some time on the engine in another stunt plane. Turns out the engine had a problem. It's repaired so we'll see how things work.
Here is a shot of the Argus - it's now very close to finished.
By the way, all the small 4S engines I've used worked best with 6 or 7 pitch props.
Bob Z

Thanx Bob. It looks the pitch can be the problem. I used my OS .52 with BE prop 12x3.5 UCT which I used also on piped Jett .50. I tried it and it worked well, so I did not try anything else. I beleieved that the small engine with max power at 12000rpm will be happy with gray Graupner 10"x4" prop the same which I use on similar model with OS .25. I did not try any other just because lap times was OK. I did not know that high RPM makes it unstable.

>I've noticed the top guns in stunt have, what I would
>consider, really big airplanes. Do big airplanes fly better?
>
>I've been sport flying Ringmaster/Flightstreak/Buster type
>planes and, I want something better for beginner class
>contest flying. A friend suggested the Banshee, Twister or a
>profile Cardinal with a Brodak .40 engine. That's about $200
>to upgrade my stunt program. That's ok with me but, I always
>want to try something different.
>
>With the work space, storage space and collection of engines
>I have, I'm a little resistant to building a bigger plane.
>My thought was to scale down a good flying plane (probably
>the Cardinal) to a smaller size. The plane would be scaled
>around a 400 Square inch wing area.
>
>Would it fly better by design or, does size really matter??
>
>
>Thanks,
>Giffy
>
>
>P.S. If size does matter, what about going the other way? A
>550 square inch PDQ Flying Clown? LOL

Giffy,

I'm a re-beginner and I have a similiar situation to yours: Not only is my building and storage area limited, my practice flying site limits my line length to about 58'. I have been looking at planes just slightly larger than what you're talking about. My current project plan is: ARF Flight Streak w/.19 engine (~400 sq.in.) to learn the beginner pattern, Primary Force w/LA.25 (~500 sq.in.), minimal paint/moneykote finish for the Lee Lorio Memorial Stunt Contest and a Peacemaker (~410 sq.in.) as a back up if (when?) I auger in the PF. I have the FS ARF with the engin mounted and run, waiting weather and time off from work to coincide. The PF is painted and ready for covering with moneykote, and the Peacemaker is framed up. The PF is my first laser cut kit and I'm really impressed! Flap-less airplane are supposed to be easier to trim and I'm thinking the PF is a good logical step up from the FS ARF. The Peacemaker should give me an introduction to flapped airplane tunning. If you like the Flight Streak, give the Peacemaker a look...
I like the Peacemaker because it is a very simple built up fuselage and, for me, the simple box type fuselage comes out lighter and stiffer than profile fuselages without increased complexity or build time. It also has an upright mounted engine which makes starting/stooge launching easier. The only mods I'm making to the Peacemaker are adjustable leadouts and adjustable tip weight. No mods to either the FS ARF or the Primary Force.
There seems to be a lot of choices in the +/- 500 sq.in. arena. Planes that were originally designed for the Fox .35. I'm hoping that a modern .25 will fly these designs on 58' lines if they aren't "over finished".

>I like the Peacemaker because it is a very simple built up
>fuselage and, for me, the simple box type fuselage comes out
>lighter and stiffer than profile fuselages without increased
>complexity or build time. It also has an upright mounted
>engine which makes starting/stooge launching easier. The
>only mods I'm making to the Peacemaker are adjustable
>leadouts and adjustable tip weight. No mods to either the FS
>ARF or the Primary Force.
>There seems to be a lot of choices in the +/- 500 sq.in.
>arena. Planes that were originally designed for the Fox .35.
>I'm hoping that a modern .25 will fly these designs on 58'
>lines if they aren't "over finished".

I don't think you appreciate the power of engines like the 25FP - it's * way more* than a Fox. A modern 25 will likely significantly overpower airplanes like the Flite Streak, and I think that 58' lines will end up way too short and you'll wind up doing 3.5-second laps. Think something like a 15FP or a Veco 19 for the Streak if you are going to use short lines.

For some references -

15FP/8.5-5 on (heavy) Ringmaster = ~4.8-5 scond laps on ~60' lines (good flying)
Veco 19/9-4 on Ringmaster = about 4.2 second laps on 60' lines (flies OK, really fast)

15FP/9-4 on Skyray 35 = 4.8-5.1 second laps on 60' lines (marginally wimpy but OK)

20FP /9-4 on a Skyray 35 (drag nearly identical to Flite Streak) = about 4.6-4.8 second laps on 62 foot lines (about 64 from handle to center) (good flying)

20FP/9-4 on a Ringmaster - right under 4 second laps on 60' lines (~62 feet from handle to center) (good flying, really, really fast)

25FP/10-4 in a Green Box Nobler = ~4.5-4.6 second laps on ~62 foot lines.

25FP/10-4/ST Needle on a Fancherized Twister - 4.7-4.8 second laps on 62' lines.

On the other hand Fox-powered airplanes do in fact work well with lines in the 55-58 foot range. Something like a Still Stuka (the original of which flew on very short lines, like 54 feet depending on when and who you ask).

My assessment is that the optimal line length for the 25FP airplanes is more like 62 feet - and that's just the lines, The required safe radius for appropriate airplanes would be more like 70 feet of clear space.

I'm not trying to discourage you, but I and the other locals have a lot of experience with the 20/25FP and it's near equivalents, If you have a limited flying space the 25FP is not a good starting point - unless you are going to significantly detune it, or have a lot of Bolly props that can be repitched to the low 3" range.

>
> For some references -
>
>15FP/8.5-5 on (heavy) Ringmaster = ~4.8-5 scond laps on ~60'
>lines (good flying)
>Veco 19/9-4 on Ringmaster = about 4.2 second laps on 60'
>lines (flies OK, really fast)
>
>15FP/9-4 on Skyray 35 = 4.8-5.1 second laps on 60' lines
>(marginally wimpy but OK)
>
>20FP /9-4 on a Skyray 35 (drag nearly identical to Flite
>Streak) = about 4.6-4.8 second laps on 62 foot lines (about
>64 from handle to center) (good flying)
>
>20FP/9-4 on a Ringmaster - right under 4 second laps on 60'
>lines (~62 feet from handle to center) (good flying, really,
>really fast)
>
>25FP/10-4 in a Green Box Nobler = ~4.5-4.6 second laps on
>~62 foot lines.
>
>25FP/10-4/ST Needle on a Fancherized Twister - 4.7-4.8
>second laps on 62' lines.
>
>
> On the other hand Fox-powered airplanes do in fact work
>well with lines in the 55-58 foot range. Something like a
>Still Stuka (the original of which flew on very short lines,
>like 54 feet depending on when and who you ask).
>
> My assessment is that the optimal line length for the
>25FP airplanes is more like 62 feet - and that's just the
>lines, The required safe radius for appropriate airplanes
>would be more like 70 feet of clear space.
>
> I'm not trying to discourage you, but I and the other
>locals have a lot of experience with the 20/25FP and it's
>near equivalents, If you have a limited flying space the
>25FP is not a good starting point - unless you are going to
>significantly detune it, or have a lot of Bolly props that
>can be repitched to the low 3" range.
>
>
> Brett

OK! you've got my attention:)

Doesn't Mike Pratt fly his Primary Force with a .25 and 58' lines?
So maybe something in the ~400 sq.in. arena and a .19 would be a better way to go? That would narrow the choices a lot...

>Doesn't Mike Pratt fly his Primary Force with a .25 and 58'
>lines?

Answer Yes, Mike recommends a bevy of 9x4 props with the OSLA25 58 foot lines and about a 5.0 lap time.

Bob Smiley
A Lancair 360 builder/flyer trying to be a modeler

>>Doesn't Mike Pratt fly his Primary Force with a .25 and 58'
>>lines?
>
>Answer Yes, Mike recommends a bevy of 9x4 props with the
>OSLA25 58 foot lines and about a 5.0 lap time.

I would point out that Mike is also flying at ~5500 feet or thereabouts.

How many of you have seen or have the micro-mini model of the Ringmaster? It flys with a Tee Dee .010. Mine sure is cute. (can I say that here?) I wonder if I can enter it in scale???