Need help please adding incidence

[andy askwith 1]

hi guys i am building a second plsne from planes its hobbystore westland lysander i am about to start on the wings were i have hit a snag its says on the plans to build it with 2degree of incidence from the root  to mid way point on the wing were it goes back to 0 degree at the tip could any 1 help me with some methodes of how to construct this please i would much appreciate this

thanks guys in advance

[Lindsay Todd]

If i'm interpreting you right this means the wing has 2 degrees of washout at the tip coming in from about half span, this would seem logical on such a design and can be quite easily done. My method would be to build from the root at zero degrees and add packing pieces under the trailing edges of the ribs from mid span end with -2 degrees at the tip. This means the wing trailing edge is higher off the building board at the tip than the root, or in this case about half way along the span. The leading edge should be parallel to the building board. Set the datum (a line from centre leading edge to trailing edge and use a protractor to measure the packing pieces you need for the -2 degrees.

hope that helps

Lindsay

 

[andy askwith 1]

hi todd thanks for the post but its the other way round its the root to midway l/e that has the +2 degree (would that be called wash in as i am just a scale virgin) and mid to tip that goes back to 0 degree

but its definatly the l/e and not the t/e that has a +2 degree

this is my first ever scale plan build just not used to building a wing with a perposely building a wing with a warp in it for all intents and perpose

Edited By andy askwith 1 on 17/01/2010 23:18:06

[mal brewer]

  Hello Andy,Lindsay is quite correct in saying the wing has 2 degrees washout at the tip,you also are correct in saying it is washin at the centre section.It  means the same thing.It amounts to a 2 degree twist along the wing from centre to tip.I personally would use the method of construction that Lindsay states,but you could also use your method,keep the tip level,and pack up the centre-section leading edge,same result ! This washin is commonly used on scale models with tapered wings,the idea is to ensure that the tips are the last part of the wing to stall.A tip-stall is a very dangerous happening for a model, as all lateral control will be lost,and the model will almost certainly enter an involuntary spin.If this were to occur at low altitude,such as on a landing approach,it would mean almost certain destruction of the model............Mal

[mal brewer]

   Sorry,I meant washout at the tip....................Mal

[andy askwith 1]

thanks guys for the replies thats made it all as clear as mud to me LOL

but as soon as i get the micro servos i will get on to it again and i will post soom pics on here to go with the fus

 

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