Druine Turbulent sizing
09-27-2010, 03:23 PM
#1
Thread Starter
Druine Turbulent sizing
My new project is a Druine Turbulent and I've been working on the CAD plans for a few weeks. I also have a 50cc DA-50 clone I want to use. The original prototype airplane is small, 22 ft span and weights around 600 lbs powered by a VW engine or others.
My problem is deciding what scale to make it. 40 percent scale would be a wingspan of around 105". No guess at the weight, but I hope to keep it light. The prototype's construction is spruce and plywood. Thin ply covering the fuse, fabric covered wing and tail surfaces. The model should be able to fly mild scale aerobatics for the Turbulent there aren't many.
At 40 percent, the scale prop size 56" would be 22". The SV-50 engine should be able to turn a 22" prop easily or even larger.
So, I'm wondering if I should go bigger. 45%?
Dave
My problem is deciding what scale to make it. 40 percent scale would be a wingspan of around 105". No guess at the weight, but I hope to keep it light. The prototype's construction is spruce and plywood. Thin ply covering the fuse, fabric covered wing and tail surfaces. The model should be able to fly mild scale aerobatics for the Turbulent there aren't many.
At 40 percent, the scale prop size 56" would be 22". The SV-50 engine should be able to turn a 22" prop easily or even larger.
So, I'm wondering if I should go bigger. 45%?
Dave
09-27-2010, 06:22 PM
#2
RE: Druine Turbulent sizing
If you look up what other 105" monoplanes weigh in at, average them out you have a good idea what you'll be able to have it come in at.
A 1/3 spacewalker comes in around 20lbs at 104" span,, I'd bet you'll be in that range
The 50cc should turn a 22-8 and pull 20lbs around no problem
A 1/3 spacewalker comes in around 20lbs at 104" span,, I'd bet you'll be in that range
The 50cc should turn a 22-8 and pull 20lbs around no problem
09-28-2010, 03:28 AM
#3
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RE: Druine Turbulent sizing
My Cunningham designed (sport scale) 1/3 scale Turbulent flies fine on a Quadra 42. I think weight is about 16.5 lbs. You are right, the Turbulent is not an aggressive aerobatic bird.
Your sizing and expectations sound right to me.
Bedford
Your sizing and expectations sound right to me.
Bedford
09-28-2010, 11:14 AM
#4
Thread Starter
RE: Druine Turbulent sizing
OK, here's my homework. Trying to compare with airplanes of similar wing loading and performance.
33 percent Spacewalker, G-38, 104"
33 percent Balsa USA J-3 Cub, G-45, 140"
33 percent Ercoupe, 50cc, 120"
33 percent Fly Baby (monoplane), G38, 112" (I once had a 1/3 Fly Baby powered by a Quadra 35 and it was a tad underpowered.)
Found a pic of a Turbulent from the UK: Harry Harland's 40% Druine Turbulent piloted by Ted Allison. Power = G38, 103"
Also found the second pic of a fellow with a 50 percent version but no other specs. Prop looks to be around 22" 24"...so could be a G-62 size.
With the full size wing span of a Turbulent assumed to be 21' 5", 40 percent = 103", 45 percent = 115", 50 percent = 128".
Now based on this, I'm really leaning to the larger size. 45 percent or even 50...
Dave
33 percent Spacewalker, G-38, 104"
33 percent Balsa USA J-3 Cub, G-45, 140"
33 percent Ercoupe, 50cc, 120"
33 percent Fly Baby (monoplane), G38, 112" (I once had a 1/3 Fly Baby powered by a Quadra 35 and it was a tad underpowered.)
Found a pic of a Turbulent from the UK: Harry Harland's 40% Druine Turbulent piloted by Ted Allison. Power = G38, 103"
Also found the second pic of a fellow with a 50 percent version but no other specs. Prop looks to be around 22" 24"...so could be a G-62 size.
With the full size wing span of a Turbulent assumed to be 21' 5", 40 percent = 103", 45 percent = 115", 50 percent = 128".
Now based on this, I'm really leaning to the larger size. 45 percent or even 50...
Dave
