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Old Nov 18, 2011, 01:13 AM
Registered User
Johannesburg, South Africa
Joined Oct 2006
43 Posts
Help!
turboprop dilemma

I've always liked the idea of building a small (parkflyer size) scale turboprop like a Dash 8, Fokker F27, Atr72, etc... But the problem is always getting the wingloading to a favourable number in order to make fly at scale speed.

Does anyone out there have any reccommendations as to which turboprops make good scale r/c planes and which ones to avoid?
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Old Nov 18, 2011, 01:00 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
13,060 Posts
You probably need to define what size you mean by small, and whether you just mean turboprop airliners.

There are quite a few small scale models flying, the Guillow's range of kits are a good example.

Slow flight usually means very light, or light and a fair bit of drag. Adding too much scale detail can raise the weight. So you may need to also decide just how 'scale' the model needs to be.
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Old Nov 18, 2011, 01:16 PM
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United States, WI, Fond du Lac
Joined Sep 2008
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If you are interested in modern airliner style planes they'll all have long narrow wings and a relatively large fuselage to haul around. Build them light (see the many build logs of jet airliners from depron) and/or increase the wing chord to get more wing area. You could also scale the fuselage down a bit, say 10% and keep the wing the same size. Won't be scale but will still be recognizable as the type.
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Old Nov 20, 2011, 04:46 AM
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Johannesburg, South Africa
Joined Oct 2006
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@ eflightray: by small I mean somewhere around the 1m wingspan range.
I also tend to build exclusively in Balsa with small brushed motors, for cost and simplicity reasons. My biggest enemy in this regard is the tendency to want a perfect painted finish which obviously adds to the overall weight, but can liven up an otherwise oversimplified model.

@pmullen503: would it not have the same effect to retain the fuselage size and increase the wing area by 10%?

Thanks to both of you for your input
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Old Nov 20, 2011, 09:33 AM
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Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
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To semi-quote Jim Ryan:

"Don't think of it as having a small wing...think of it as having a large fuselage."

If you want to go with aircraft models like these in the 39-40" wingspan, you will have to build VERY light to have the models fly in a sort of scale-like fashion.

At 39-40" span, I would suggest that slight increase in wing (and tail!) area that you mention. As long as the wing is scaled in a way that keeps the proportions correct, it can be made larger with minimal effects on the looks of the model.

Wanting a perfect painted finish on small flying models like these is sort of mutually exclusive with your other requirements. I would decide if I really wanted to look at the model on the ground, or flying in the air and optimize the finish approach accordingly.
If you prefer seeing it fly, go with a light finish like tissue, Coverlight or Litefilm over open structure and give up the perfect scale looking finish.

Going slightly larger, say 1.5 meter wingspan still allows the use of inexpensive brushed motors, if you already have them lying around, plus the benefits of lower wing loadings. However, in this day and age of very inexpensive brushless systems, (CD Rom type outrunners like the BP-21 with ESC and prop for well under 20 dollars, it is not true that you must be brushed to be inexpensive...
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Last edited by Thomas B; Nov 20, 2011 at 09:40 AM.
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Old Nov 20, 2011, 10:35 AM
Übung macht den Meister..
Deuce's Avatar
United States, OR, Fairview
Joined Jul 2006
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If you are not restricting your subject to civilian aircraft, a military type that is less modeled is the FMA IA-58 Pucara, an Argentinean COIN aircraft:





I've contemplated this subject, but I'd likely try something closer to 1.5M span (or larger) without modifying outlines. However, the wing is a simple platform, and you could easily increase the chord and/or span without being too obvious about it.

James
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Old Nov 20, 2011, 01:38 PM
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United States, WI, Fond du Lac
Joined Sep 2008
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Quote:
Originally Posted by springbok View Post
@pmullen503: would it not have the same effect to retain the fuselage size and increase the wing area by 10%?
Sure, the idea is to increase your wing area relative to the fuselage in a way that still retains the "look" of the aircraft. Choosing an obscure subject helps in that most folks won't recognize the airplane, much less notice that the wings look larger than they should.
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