High/low aspect ratio stab/elevator..what's better?

I decided to give some more sq" to the "Cheeseler" tail.

I can give it more span (easy) or increase it's lenght (not so easy)...

High aspect - more LE.

Low aspect - more "surface drag"?

HAR beter? LAR better? No difference?

You can all have fun at my expense, except Len (he already spent his quota).

Ion (I'll shoot back) Muniz

>I decided to give some more sq" to the "Cheeseler" tail.
>
>I can give it more span (easy) or increase it's lenght (not
>so easy)...
>
>High aspect - more LE.
>
>Low aspect - more "surface drag"?
>
>HAR beter? LAR better? No difference?
>
>
>You can all have fun at my expense, except Len (he already
>spent his quota).
>
>Ion (I'll shoot back) Muniz

Ion,

No offense is intended, but you appear to be having all the fun at our expense. First you wanted to know how to improve a Nobler when that story has been told many, many times over just within the constraints of Mr. Gieske's career.

Then we find you are building a Chizzler, in itself claimed by many to be an improvement of the Nobler.

If you want a good Classic model, pick one and build it.

If you want a current PA model, pick one and build it.

If you want to design an all-new, or just partially-new, model of a specific size and for a specific powerplant, just say so.

Ion,

I suggest you do some reading in old Flying Models and Stunt News magazines. You will find that a plane called the Lazer using a lower aspect ration stab/elevator has been copied for use in some really high zoot modern designs. I have seen these planes fly and they will corner on a dime and give nine cents change. In fact the entire Japanese team was watching and ooohing and aaahing when one of these planes was doing the backside corners of the triangles at the 1997 or 98? Nats (Don't remember which right now). So, I could say that they were really doing some stargazing!

('Rhoids acting up again, Dan?) Don't make me come over there. (There's a blister on your nose already that is ready to bust..)

The correct answer to Yon's question is: notice that all the extremely ELEGANT looking stunt models have a higher aspect stab. I point you to the exquisite classic Cobra for an example. I might also point to the Stilleto.

Meanwhile, those bland looking Nats winner ships like Ted's Pursuit now use lower aspect ratio stabs. (Notice that Ted has to spruce up the cowl to compensate for the blandness..)

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Ion, do you want something that IS good, or just LOOKS very good?

Speaking of Chizlers and Ted, they go together quite well! Just do whatever Ted did, including flying it with great precision and skill.

(Hey, wait, that's what The Daniel said, wasn't it?)

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"Law school has been described as a place for the accumulation of learning. First-year students bring some in; third-year students take none away. Hence it accumulates." -Daniel R. White

Hi Ion, first and foremost, stunt is about freedom. Alot of what we like about stunt is the freedom to do what we want, how we want and use whatever we want. That said, alot of classic models are good proven designs. The Chizler, as Ted fancher has proven is a very competitive design today just the way it is. I can personally attest to the effectiveness of the Mini Mako Shark in the hands of 1978 Nats Champ Bob Whitely. I watched Dave Sabon put in a devastating flight with his Olympic Mark VIII in wind that almost blew down our sun shade. We all know what a stock Oriental can do. You might want to hold off on the aerodynamic mods and save it for something not quite as proven.

LAST EDITED ON May-08-04 AT 00:26 AM (CDT)
 
Yea Ion,

Save you mods for those unproven designs like the TP & Stargazer, only 6 Nats wins - really unproven designs, I bet they could really be improved upon a lot. (NOT!) Oh, yes, there is another airpalne design that uses the lower aspect ration stab/elevator too. It's not well proven either, only about 4 or 5 nats wins and a world championship there too. Too bad the designer decided to switch to warbirds, one a four engined one. Am I getting my point across Ion?

Why do you want to change the Chizler? Built right and light, it is probably one of the best 35 size unpiped designs you could ever hope to fly. Fancher's is one of the best Classic ships around, even with his ribs that ended up a bit thinner than the plans show and a fixed flap/elevator ratio. (He sanded the stack too much and did not have time to make another set of ribs. We were both trying to get these finished before a VSC several years ago.) My first Chizler was built the same time as Ted's. Mine was about 4 oz heavier, but I could adjust the flap/elevator ratio and found that for my weight, about an .8 to 1 ratio gave me a better turn. I flew both models. Mine had a better turn, but his handled the wind better because it would not wind up as much. My second Chizler was that 4 oz lighter, used a .7 to 1 flap/elevator ratio and it would turn as good as anything except for the best piped ships here on the West Coast.

I would suggest building the thing stock, except for your OS 25 VF with a pipe. That combination has been on my list of things to do for a long time. I see no reason to even think about changing the numbers. (Also, I know Ted has toyed around with retrofitting his Chizler for that power train.)

If you want to experiment, fine, but why not do one first with numbers that work. And the Chizler works. Then when you change, you will know if you have made an improvement.

>I decided to give some more sq" to the "Cheeseler" tail.
>
>I can give it more span (easy) or increase it's lenght (not
>so easy)...
>
>High aspect - more LE.
>
>Low aspect - more "surface drag"?
>
>HAR beter? LAR better? No difference?

I think that lower aspect ratio is probably better, mostly just from the large database of experience using this approach - i.e. all but one NATs winner since 1990 had some variation on the theme. Granted that's only 4 different designs (Impact (90, 91, 92, 93, 94, 98, all PW) and Trivial Pursuit (95 (TGF), 97 (DLF), 99 (DLF), 00 (TGF), 01 (DLF), 03(DLF)) are most of them, with a Patternmaster (96) and a P-51 (02) thrown in) but it's at least an indication that the most successful pilots think it's a good idea, if not of any actual intrinsic value.

I also think that the difference will probably be invisible unless you get everything else perfect. The effect of this sort of design detail is frequently *grossly overstated* and it's mostly invisible and thus will be swamped by other issues. The wrong glow plug, or having 1/16th oz of excess tipweight, will completely overwhelm any value you get from such a minor change.

Hi Brett,

Yes, most anything can overcome small design details such as empanage aspect ration. However, if all else is nonimal (i.e. 1/16 ounce too much tip weight may not be out of nonimal for a particular design), I believe the lower aspect ration will be of more assistance in creating good flat bottoms on square and trianglualr manuvers. ( I know, you already said that lower is better!)

One obvious structural advantage of shorter span would be less deflection under load..

A stiffer structure is almost always more desirable.

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"It rubs the lotion on its skin,
it does this whenever it's told..
It rubs the lotion on its skin,
or else it gets the hose again.."
-Buffalo Bill, in "Silence of the Lambs"