I was thinking of making a wing of solid Pauliwonia and then bagging it in glass, and I thought I would canvas some opinion on which foil I should use. First, my design brief:
- it will be a plank with semi-fuz, similar in planform to a Reaper.
- it will be 60"
- It will be made from two 30" pieces of Pauliwonia wood hand-planed into shape - so it can't have any real concave shapes (I realise self-stable foils require a reflexed trailing edge, and thus a transition from convex to concave on the top of the foil - but I will have to add the reflex with full-span elevons trimmed up a bit).
- Yes, i'm mad
- I don't need this thing to break records, i'm a relative newbie to DSing, but not to sailplanes. It needs to simple to set up and balance, be stable and can DS well enough to have good fun in 20-40 knots of wind, and track well.
- I guesstimate the AUW to be around 1.5-2Kgs.
- it will not be internally ballastable.
- I will run standard servos in it.
- the wood blank im starting with is 25mm/1" thick.
- be bloody tough!

What should I use?

If you can put some sand paper on a pipe you can get reflex in your solid wood wing. I did one of my first one's and it was an E-214 which has camber. This wing was for a glide recon that was eventually dropped from an F-15. The wing I built was for a 200% proof of concept and was flown as a sloper. The wing's were solid balsa. I used 3 carpenter's levels to get the shape . 2 to support the balsa and the third had rough sand paper on one flat and finer grit on the other. I did rough shape it using a 13 degree plane.

Oh I also had aluminum templates glued to each end and the edge's of the templates were Majic Markered so I would know when I was getting close with the rough sand paper.

If you're good enough at woodworking to have a sharp hand plane, you should be able to work a scraper. You can get curved ones to handle reflex curvature.

http://www.highlandwoodworking.com/c...ersetthin.aspx

-David

That plank sounds great! I agree with the others- use a proven plank airfoil like a pw 51 and work out some way to get the concave shape into it. I can imagine it will be pretty heavy though, with plank foils being on the fatter side. Good luck with it, it will be worth the work because the finished product will be almost bullet proof!

I'm a qualified cabinet maker - but haven't been in the trade for many years. So working with wood is 2nd nature - I just don't have to machine tools anymore

Sent from my Lumia 800 using Board Express

I got one vote for the PW51 - any others?

I like the idea of a pipe with sand paper to get the concave on the top.

My RT30 and RT28 were PW51, RT42 is PW98

I felt the 51 had better handling and nicer flying

Your plan sounds good. Have you seen this thread:

http://www.rcgroups.com/forums/showthread.php?t=984619

Might have some useful ideas for you.

Originally Posted by ALEX HEWSON

My RT30 and RT28 were PW51, RT42 is PW98

I felt the 51 had better handling and nicer flying

I agree with Alex.
The 51 is a good alrounder , frontside sloper and dser. Fly's well inverted and is good for turning.

The 98 is faster at low CL range , and doesn't like to be inverted.

Go the 51..

Ok, done - PW51 it is. Anyone got the co-ords file? What app do people use (free) to print out profiles to make the templates?

I have profile-22 and I have a 10% PW51 file not the original. What % is the original?

Also, I assume there is no wash-out on a plank of this sort?

Use the search tool at the top. It is in a couple of places on RC Groups

Original is about 8.5%...just thin the one you have.

Take it down to 7.5% if the root cord is more than 250 mm & leave it at 8.5% for the tip

I have this on good authority

Here you go

Rick

Thanks guys. I will need to work it all out proper now Root chord of a 60" reaper is about 230mm, so I think it will be 8.5% the whole way.