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Old Dec 13, 2002, 10:03 AM
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Berkeley,CA
Joined Nov 2002
14 Posts
Guillows Conversion of DC 3

Hi everyone, I'm building a scaled up DC 3 - just scanned plans and doubled everything - gives scale of 1/16. Hope to bring it in at 5 lbs and plan on glassing over 1/32 balsa. Concerned about what power to use. VEry confused about geqaring ,no gearing, motor size etc. Looks like 3 blade 8 x 6 will fit. Will use 2 escs and 2 battery packs.
Also concerned about the airfoil that is provided it is thick and flatbottomed but that is all I know - this model was for display. The DC 3 used NACA 2215 root and NACA 2206 tip. I also have been trying to build this in X-plane so I could see how it flys - it is only simulator I could find to use with my MACs (works with windows too)
Anybody with thoughts and ideas much appreciated. Will provide pics soon.
Best
jim
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Old Dec 13, 2002, 02:24 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,761 Posts
I'll take a stab at it..

Jim

You might find that 1/32 sheeting is awful thin and can be difficult to handle on a plane this size. Have you run the wing area?

In terms of airfoils- I wouldn't trust the Guillow's stuff very far. Full scale airfoils are no help at model sizing. There are a bunch of foamie DC3s out there in this size range- if they fly OK, steal their airfoil.

In terms of power systems- an 8 x 6 three blader on probably 175 watts or so should have ample power reserve. (I fly a P-38- 4.5 lbs, 200 watts per motor- flies like a P-38- I figure a DC-3 doesn't need quite that level of power, but having some extra on tap is not a bad thing-= 350 watts (175 x 2) should be plenty.)

If you're willing to do the $$$ of brushless, then your setup works fine- basically do two motors, and ESCs- you might get away with one battery though, but if you don't mind charging two, that works well. (that's what I'm using.)

Brushless motor suggestions- the simple and easy system that comes to mind is either a Jeti 15/4, or a Mega 22/10/6. Run the motors on 7 cells- you should hit 175 watts or so on that prop (guessing a bit here- I run two bladers) A pair of 4/5 AUP 1700 NiMH cells- you'll be up there for a long time, lots of power, about as light as it gets- your total motor system should be about 22 ounces- competitive with glow in my book. Plus if your bird gets a little porky, add and extra cell, run a two blade prop, and you'll have 400 watts easy- probably enough for a 6 lb bird. I hate gearboxes- for your setup they're unnecessary unless you go to brushed motors.

The cheaper alternative if you come in light is the 450 Turbo motor- run one ESC and battery pack- should be close to the same weight, but would be happier in a 4 lb airplane. Some folks are flying Beauforts using this motor- you need to go down to 7 cells though which gives you 300 watts total (and not as efficient as the brushless either, although not bad.)

Hope this helps,

Sam
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Old Dec 13, 2002, 04:54 PM
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Berkeley,CA
Joined Nov 2002
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Sam, thnx for info. Near as I can figure I have about 492 sq inches of wing @ 5lbs AUW gives about 23.4 oz/sqft. So to save money I want to try the 400 size first. One thing confuses me what do watts have to do with things - I know VI = watts but now what does that have to do with motor I choose and gearing choices. So at 7 cells that is about 8 volts but now where do the amps part of equation come from. BTW I just purchased an Astro Watt meter - haven't tried it yet.
I've emailed Guillows to try to find out about airfoil. I've built the in board portion of wing and it is thick and flat bottomed - TLAR but what do I know. So I am probably going to try it.

Since I started this I discovered Top Flight has a DC 3 model - does anyone have the plans and can provide me the template for their wing both root and tip.

jim
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Old Dec 13, 2002, 05:12 PM
got any foam to bash?
Tom Hunt's Avatar
Lake Grove,LI, NY
Joined Aug 2000
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Jim

near 500 sqin seems more like a pair of direct drive lower current (15-20amp brushless motors, (yes, mega 22/10/6 of Phasor 15/4 on 7 cells each might get you 20 amps or so on some 8" 3 bladers

geared 480's would be another way out. or geared mega 16/15/x motors in brushless.

You would definately have to build it like a BIG Guillows kit to fly it on geared 400's. very light weight stick construction with little sheeting.

Watts = volts x amps. We generally use 1v/cell for an estimate before we take a whatt meter reading.

Dont be afraid of a 15% flat bottomed or 2215 (or 2315 to move the high point back) even in a model this small. A lumbering model like a DC-3 will not really notice the difference. I would thin it to no less than 12% at the tip though, just to keep the LE radius from getting too small and causing pre-mature tip stall. Best to twist the wing about 3-4 degrees regardless of airfoil used.

Good Luck
Tom Hunt
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Old Dec 13, 2002, 05:19 PM
got any foam to bash?
Tom Hunt's Avatar
Lake Grove,LI, NY
Joined Aug 2000
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BTW

I think there is a typo on the UIUC airfoil usage database. The tip airfoil was more likely the 2209 like the DC-2. 6% is mighty thin and usually reserved for jet fighters!

Tom
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Old Dec 13, 2002, 05:20 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
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Jim, nose around a bit more

Jim,

Keep doing some searches on this board. There are several examples of DC3s in that size.

Sam
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Old Aug 19, 2006, 11:59 AM
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Joined Jun 2006
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DC-3 plans

Jim,

Is it possible to mail the scan of the original guillows plans to me?
My mail adress is: straat1980@hotmail.com.

B.t.w. everyone with digital DC-3 plans is most welcome to mail me the plans .

Greetz Bas.
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Old Aug 19, 2006, 10:46 PM
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Grove City PA basement/park
Joined Feb 2005
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DC3 and other Enlarged Guillows

I did a build thread on mine a while back. It's here somewhere. I'll be following this one.

I cheated on mine and added span, to give it some kind of real wing area. The DC3's span is misleading, since it is so highly tapered. Many good flying scale models have larger chord at the tips. I should have done that, as my wing would have actually looked more scale that way, to balance out the added span.

I'll be following this one. I did a 125% enlarged Guillows Hellcat, and a 200% enlatged Guillows FW190.

Tom Hunt, I added washout to mine. Probably 3 to 4 deg, as I think you were stating about washout. I've heard many folks say only 2 deg, but the 3 to 4 has seemed to work well for me. Want to come here an test fly this plane for me. Its too pretty, I'm afraid to.
As for the airfoil, it looked fairly scale to me. Fairly thick airfoil. Wonder if it will work well, as I used it from the original plan formers?

Quote:
Originally Posted by Easterbunny
Jim,
Is it possible to mail the scan of the original guillows plans to me?
My mail adress is: straat1980@hotmail.com.
B.t.w. everyone with digital DC-3 plans is most welcome to mail me the plans .
Greetz Bas.
Well you could just ask for them, from the guy I gave my set of original plans to. As always, they didn't build it. Gave away many of my Guillows plans to folks here. I'd give you them if I still had them.

Bill
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Old Aug 23, 2006, 07:31 AM
got any foam to bash?
Tom Hunt's Avatar
Lake Grove,LI, NY
Joined Aug 2000
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Quote:
Originally Posted by scratchandbash

Tom Hunt, I added washout to mine. Probably 3 to 4 deg, as I think you were stating about washout. I've heard many folks say only 2 deg, but the 3 to 4 has seemed to work well for me. Want to come here an test fly this plane for me. Its to pretty, I'm afraid to.

Bill
No Bill, I DID mean thickness... 6% is too thin for many aircraft of that era...

but YES 3-4 deg of twist would be a very wise idea in a model that size.

Bring it up to the NEAT fair.... (www.neatfair.org) in 3 weeks and I'll test fly it there for you (morning or evening, not in the middle of the day).

Tom
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Old Aug 23, 2006, 05:24 PM
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Grove City PA basement/park
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Quote:
Originally Posted by Tom Hunt
No Bill, I DID mean thickness... 6% is too thin for many aircraft of that era...

but YES 3-4 deg of twist would be a very wise idea in a model that size.

Bring it up to the NEAT fair.... (www.neatfair.org) in 3 weeks and I'll test fly it there for you (morning or evening, not in the middle of the day).

Tom
I'd love to try to do both! It is a well built plane with full house controls. I'm sure you're a much better flyer than me , and I know you have a lot of experience with these small balsa kit conversions.
We used to have a family cottage on Canandaigua lake, NY. I love the country. Been to the Catskills before too.

Bill
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