Building a Steen Skybolt from 3 views

[inSANe DIEGO]

Hello all
I posted this in the Builder's Workshop forum and after some thought, maybe it should be here.

I am starting to design a small aerobatic biplane (around 25" MAYBE up toward 30" wingspan if I have to) modeled after the Steen Skybolt D( http://www.steenaero.com/ .) I would like strong aerobatic performance with respectable speed. My current questions are...

1) What airfoil would be good for this size and type of plane?

2) What range wing loading should I shoot for? I don't want the super light "leaf with a powerplant" effect like the 3D purpose-built airframes. I want this plane to fly like it has an airfoil for a reason and therefore I'd like there to be a decent amount of energy retention. In other words I'd like it to fly on its wings not its prop.

3) When calculating wing loading, is there a difference in how a biplane uses it total wing area compared to a monoplane? Or is there some sort of adjustment due to the wings being in close proximity to each other?

4) Are these parameters too ambitious for a plane this size?

That's all for now.
Thanks
John

[fdix]

1) recenty everybody seems exited about the NACA 63010 for small aerobatic stuff

2) I would go for about 30-40g/dm^2

3) because we are talking about wings operating at low Re numbers it is probably safe to sum the areas of both wings.

4) nothing is too ambitious :D

How are you planig to build? With what materials? I would go for depron fuse and hot wire cut foam wings...
To make construction easier I would go for 30" span

[inSANe DIEGO]

fdix

Thanks for the reply. Now I just need to convert metric to U.S. standard for the wing loading. Is that 30-40 grams per decimeter squared?

I printed 25" and 30" span plan views. The 30" looks better to me. I plan to build a balsa sheeted foam core wing. Fuse is undecided. I'd like to try depron. What's best to glue it with and can I incorporate curves and round edges easily with it? My orginal plan was to shape a foam fuse then hog it out where foam wasn't needed. Then again... If I do a balsa fuse and be very smart with where the extra wood goes, would foam or depron really be that much lighter on such a small airframe?

I would like to use my PJS 1000 outrunner in this plane w/ 3s lipos. Does that sound about right for power? Too little? Plenty? Too big (just adding weight?)

John

[fdix]

1 g / (dm^2) = 0.32770583 oz / (foot^2) I love google ;)

For the construction... well it all depends on your target AUW. You probably will be somewhere around 500g (17oz)

Depron construction is very light but compound curves are challenging, you have to work with a heat gun and make some experiments.

The PSJ 1000 looks like overkill to me. A PSJ 550R would probably do, It would also have the advantage that you only need a 2s pack.

Before deciding what construction technique and what motor you are going to use it would be a good idea to know what AUW you are aiming at.

[inSANe DIEGO]

Thanks for the conversion formula. I did it a lengthier way by converting the seperate units first. This was way faster.

Naca 63010... Do you have a profile or a link to one I can see. I did a quick google and it looked a little confusing- not much time right now to sort it out.

Maybe I should bump up the size of the model then? I didn't think I had that much power in the 1000. Apparently max static thrust is around 40oz with a 3s turning a 12x4.7 prop. pulling 25 amps. I'd like to run the motor more conservatively and pull around 17 - 20 amps max. 10" - 11" prop?

The size of the plane is not as much of a concern as using the motor is. I've had this motor sitting around for more than a year and don't want to invest in another power system. That said... maybe an AUW of around 25oz. should leave me with ample power. Do these numbers sound like they jive? Now what are we talking for wingspan if I do the foam core wing and foam (with some balsa here and there) fuse? 36"? I'd also like to make it fairly scale which means landing gear and canopy. Not worried about flying wires nor totally scale size prop though.

Also... I'd like to use extra batt. capacity to make flights around 10-15 minutes possible. Or also use some of my nimh packs- so I figure I'll shoot for the 10 - 11oz. wing loadings with the lipos so I don't have a brick when the nimh's go in.

How's this all sound? Doable?

[fdix]

I attached a print screen form xfoil of the NACA 63010 and also attached a zip file containing the .dat file with the coordinates.

Hmm I didn't know you were designing a plane around a motor... so we'll have to start over again. I'll have a look at the 3 side views when I got some time!

Why do you want to run the motor in a more conservative way? You don't have to run in flat out so with a larger prop you've got some power reserve to save your aircraft in critical situations.

[inSANe DIEGO]

Thanks for the profile.

Sorry about neglecting to specify that the plane is being designed around the motor.

I have converted the PDF 3 views file to DXF format so I can make plans in AutoCAD. I can send you PDF, DXF, or DWG so you don have to hunt it down.

As for running the motor conservatively. That's what I meant. I don't want to design to max performance specs. I'd like some reserve power and figured also that an 11 x 4.7 or so prop would be too big a diameter for use with gear and R.O.G. flying.

Busy day for me at work so I won't be able to check in as much today.

Thanks a bunch for your help.

John

[rcfoamy]

Quick question, I brought up naca 63010 from my wing master program and it does not look the same until all of the camber and camber position is 0 then when printing this it becomes naca 00710, any ideas?

Thanks,

[fdix]

Scott
sorry I'm not familiar with the wing master prog...

John
yeah please send me the dxf file. Would make life more simple to calculate areas! Send it to mailto:mark@infinityinfinity.com (mark@infinityinfinity.com)

[inSANe DIEGO]

Mark

On its way!

John

[inSANe DIEGO]

Mark

Did you get the file?????

[Nitro Blast]

Hpw's the plane coming along? I'll be at the field this Sunday if you can stop on by.