SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Mar 20, 2002, 12:08 AM
I'm Charged!
megawatt's Avatar
The end of the Oregon trail
Joined Jan 2001
1,035 Posts
Question on washout

When adding washout to a wing, should the "twist" start at the root of the wing panel and gradually increase out to the tip. Or should the "twist" start at some point on the outboard portion of the wing panel, thereby leaving a portion (inboard) of the panel flat? Or, does it matter ....Jeff
megawatt is offline Find More Posts by megawatt
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 20, 2002, 01:08 AM
Registered User
davidfee's Avatar
San Diego, CA, USA
Joined Mar 2001
3,068 Posts
I think most model builders just use a gradual (linear) transition from root to tip, but I have seen some wings (jig-built and molded) which had a non-linear twist. That is, the wing was essentially flat most of the way out, and then the last ~1/4 of the wing got all of the twist. I've even seen one set of wings where the washout was only in the last 10% of the span. It's all a matter of how carefully you want to massage the lift distribution across the span.

Linear twist is easiest in most cases, and generally works just fine.

-David
davidfee is offline Find More Posts by davidfee
Reply With Quote
Old Mar 20, 2002, 09:48 AM
I'm Charged!
megawatt's Avatar
The end of the Oregon trail
Joined Jan 2001
1,035 Posts
Thank you David. Wasn't sure on this one. I guess as long as you insure that the inboard section of the wing has a bit higher AOT than the tip, then it shouldn't matter if all of the washout is located at the tip, or starts inboard and gradually increases out to the tip. It should still reduce the chance of the tip stalling first.
...Jeff
megawatt is offline Find More Posts by megawatt
Reply With Quote
Old Mar 21, 2002, 11:40 AM
Registered User
Blacksburg, VA 24060 USA
Joined Feb 2000
3,229 Posts
Megawatt,

go to your local general aviation airport and look at airplane wings from their trailing edges. You'll find on high-wing Cessnas (IIRC) that the washout is in the outer wing panels. I looked at the washout on a Piper twin, and it seemed to be linear from the engine nacelle out to the tip (IIRC). I suppose the amount of twist and its exact location is dependent on a lot of factors. Not being an engineer, I use the "TLAR" approach. It's worked for me on a couple of my models, not so good on a couple of others. And it can be a bear to adjust to get the results you want.
JRuggiero is offline Find More Posts by JRuggiero
Reply With Quote
Old Mar 21, 2002, 01:12 PM
Registered User
Houston, Texas
Joined Oct 2000
1,030 Posts
You can make the leading edge out at the tip blunt
and sharper at the root and get the same effect as washout. You can also add stall strips at the root. Just another way.
flailing is offline Find More Posts by flailing
Reply With Quote
Old Mar 21, 2002, 06:00 PM
It's just PLANE silly!
balsaman's Avatar
Ontario
Joined Jan 2002
915 Posts
foam wings

It's easiest to make it linear. Especially on foam wings, but also on built up wings so thats how most models are designed. The KISS method is always a hit for me

Eric
balsaman is offline Find More Posts by balsaman
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question on 9V Rayovac Batteries for Litestick. mrebman Parkflyers 1 Jul 28, 2001 10:51 AM
battery charger question on Sky Scooter Pro LuckyArmpit Beginner Training Area (Aircraft-Electric) 14 Jul 08, 2001 09:36 PM
A Question on Jets... jyoder111 Electric Plane Talk 1 Jun 23, 2001 09:23 AM
ME-262 - Question on duct fans spitfire Electric Ducted Fan Jet Talk 4 Jun 01, 2001 10:31 PM
Pico stick newbie question on battery and charger Skywalker Parkflyers 2 May 07, 2001 10:53 PM