SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 12, 2012, 03:08 AM
Registered User
taurineman's Avatar
Wellington, New Zealand
Joined Sep 2009
436 Posts
Question
Foil for 60" DS plank wooden wonder

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?
taurineman is offline Find More Posts by taurineman
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 12, 2012, 09:28 AM
Registered User
prodjx's Avatar
Joined Jan 2007
4,870 Posts
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.
prodjx is offline Find More Posts by prodjx
RCG Plus Member
Reply With Quote
Old Oct 12, 2012, 09:30 AM
Registered User
prodjx's Avatar
Joined Jan 2007
4,870 Posts
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.
prodjx is offline Find More Posts by prodjx
RCG Plus Member
Reply With Quote
Old Oct 12, 2012, 03:58 PM
the occasional flyer
rothlisburger's Avatar
Rexburg, ID
Joined Jul 2008
529 Posts
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
rothlisburger is offline Find More Posts by rothlisburger
Reply With Quote
Old Oct 12, 2012, 06:10 PM
R.I.P
josh18's Avatar
Australia, QLD, Toowoomba
Joined Jan 2010
3,564 Posts
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!
josh18 is online now Find More Posts by josh18
Reply With Quote
Old Oct 12, 2012, 07:17 PM
Registered User
taurineman's Avatar
Wellington, New Zealand
Joined Sep 2009
436 Posts
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
taurineman is offline Find More Posts by taurineman
Reply With Quote
Old Oct 13, 2012, 04:20 AM
Registered User
taurineman's Avatar
Wellington, New Zealand
Joined Sep 2009
436 Posts
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.
taurineman is offline Find More Posts by taurineman
Reply With Quote
Old Oct 13, 2012, 06:30 PM
PB of 733kph
ALEX HEWSON's Avatar
Christchurch, New Zealand
Joined Jul 2005
5,710 Posts
My RT30 and RT28 were PW51, RT42 is PW98

I felt the 51 had better handling and nicer flying
ALEX HEWSON is offline Find More Posts by ALEX HEWSON
RCG Plus Member
Reply With Quote
Old Oct 13, 2012, 08:17 PM
Registered User
New Zealand, Auckland
Joined Apr 2012
37 Posts
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.
ReaperRob is offline Find More Posts by ReaperRob
Reply With Quote
Old Oct 13, 2012, 11:29 PM
ERS....Energy Retention System
timbuck's Avatar
gold coast australia
Joined Aug 2008
5,593 Posts
Quote:
Originally Posted by ALEX HEWSON View Post
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..
timbuck is offline Find More Posts by timbuck
RCG Plus Member
Latest blog entry: Gizmo 36 pics
Reply With Quote
Old Oct 15, 2012, 04:20 AM
Registered User
taurineman's Avatar
Wellington, New Zealand
Joined Sep 2009
436 Posts
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?
taurineman is offline Find More Posts by taurineman
Reply With Quote
Old Oct 15, 2012, 04:25 AM
PB of 733kph
ALEX HEWSON's Avatar
Christchurch, New Zealand
Joined Jul 2005
5,710 Posts
Use the search tool at the top. It is in a couple of places on RC Groups
ALEX HEWSON is offline Find More Posts by ALEX HEWSON
RCG Plus Member
Reply With Quote
Old Oct 15, 2012, 07:03 AM
ERS....Energy Retention System
timbuck's Avatar
gold coast australia
Joined Aug 2008
5,593 Posts
Original is about 8.5%...just thin the one you have.
timbuck is offline Find More Posts by timbuck
RCG Plus Member
Latest blog entry: Gizmo 36 pics
Reply With Quote
Old Oct 16, 2012, 06:06 AM
Scorpian 60'' 2012
BMtech's Avatar
Kurrajong Australia
Joined Jul 2005
1,457 Posts
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
BMtech is offline Find More Posts by BMtech
Last edited by BMtech; Oct 16, 2012 at 06:10 AM. Reason: added file
Reply With Quote
Old Oct 18, 2012, 05:06 AM
Registered User
taurineman's Avatar
Wellington, New Zealand
Joined Sep 2009
436 Posts
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.
taurineman is offline Find More Posts by taurineman
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Foils for 60" planks in Light air yellowblue Slope 119 Oct 06, 2014 03:41 AM
suggestions for a foil for a plank ? epkoncept Flying Wings 18 Jul 07, 2006 08:29 AM
Discussion Could an RG15 foil work for a plank? THUREN Slope 12 Apr 05, 2006 11:45 PM
Help choosing Airfoil for 60" DS Plank occy Dynamic Soaring 5 Oct 20, 2003 03:02 AM