Airfoil choice and CG on own design delta

[pilotrcuk]

Hi All,

I'm keen to draw up plans for a delta EDF model - to be honest I'm not sure yet if I want to go with canards or not.

I've built and flown a Laser Arrow before, which was great, but this project is going to be smaller, off the top of my head about 36" span.

Whilst I want it to be fast, I want it to be nice to fly throttled back too. I wish I'd taken root and rib templates of the Laser Arrow, as I usually do, to play about with reducing and thinning.

Can you give me ideas for suitable wing sections, where to go to get templates and info, and my biggest concern, getting a ballpark CG? Most of the CG calculators I've seen have been for a conventional wing/tail layout.

Thank guys!!
Al

[nmasters]

This thread discuses how to determine the CG of a delta: http://www.rcgroups.com/forums/showthread.php?t=666614

Any airfoil section that's suitable for tailless will work for a delta. That would be all of the fully symmetrical sections and reflexed sections like MH45, PW51, PW106, HS520 etc

[pilotrcuk]

Thanks for the speedy info. Can you point me to any airfoil resources, or reference any symmetrical sections?

Thanks,
Al

[DT56]

http://www.ae.uiuc.edu/m-selig/ads/coord_database.html

http://www.mh-aerotools.de/airfoils/

http://www.b2streamlines.com/PWairfoils.html

[pilotrcuk]

Thanks DT56 - I actually recognise a few of these sites from when I was into comp thermal-duration soarers!! (long time ago) Don't think this project will be getting SD7037 though :D

[nmasters]

The HS sections aren't in the UIUC database. There's a link to them here (http://www.rcgroups.com/forums/showthread.php?p=11469388&highlight=hs+520#post11469388) and a comparison polar showing the affect a trip strip has on the pitching moment.

--Norm

[DanSavage]

This thread discuses how to determine the CG of a delta: http://www.rcgroups.com/forums/showthread.php?t=666614

Any airfoil section that's suitable for tailless will work for a delta. That would be all of the fully symmetrical sections and reflexed sections like MH45, PW51, PW106, HS520 etc

Hello,

FWIW, I used the as calculated by the graphical method using the centroid function in my CAD program on both of my F-106 models. My current F-106 model is flying at 24.5% MAC.

In fact, I use this method almost exclusively to calculate the CG for all my designs as well as others'. It has proven to be a very reliable way to find a good starting point for test flights, especially with weird planforms like those found on most modern fighter jets. We've also used this method to correctly calculate the CG for a twin edf-powered model of the Airbus Beluga.

I used a modified TSAGI 8% (thinned to 5%) on my F-106 that I obtained from the UUIC site for the root chord and the same airfoil at the tip, but modified for the scale leading edge conical camber.

Dan

[gerryndennis]

Peter Russell had several Delta plans published in the UK in the 70's. They flew really well and quite fast. He used a 12% thick symmetrical section (NACA 0012). using a 60 degree leading edge angle the CG came out at 50% of the root chord.

Someone used his plan as the basis for a model with a fuselage and canards, presumable moving the CG forward to suit.

I would think a NACA 00XX section (choose your thickness to suit) would work fine.

Have you tried the Geistware CG calculator?
http://www.geistware.com/rcmodeling/cg_super_calc.htm

or

http://adamone.rchomepage.com/cg_canard.htm