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Building New Wings

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Posted

After getting the new project home, an Avid mod A, to Ohio, I think I'm going to scrap the old speed wings and build a new set of extended wings. Does anyone have a templet or a tracing of the speed wing ribs that I could borrow or get a copy of? Many thanks for your help.

Jim

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Posted

I would build the Kitfox airfoil if I was you.

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Posted

One can order new ribs from Kitfox for the 1, 2, or 3 airfoil. I just bought 2 for patterns. Pricy, but available.

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Posted

Thanks guys for the info.  What would be the advantage of the Kitfox rib over the Avid rib and which Kitfox rib is best?

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Posted

The Kitfox 4 and later wing rib is a faster flying wing than the earlier undercambered wings that Avid and Kitfox used.  It also does pretty good for STOL performance, so most would say it's a better design then the earlier one.  Problem is that the flaperons on early wings doesn't match up with the Kitfox later style flaperon.  The Kitfox 4 and later also use aluminum angles riveted to the wing top and bottom to carry the flaperon.  Here is an Avid STOL wing with the Kitfox 4 brackets next to them.  Note the difference in mounting of the flaperon hinges.  The Avid Speed wing rib isn't that bad really, some who have put wing extentions on have liked the results.  Also some have built long wings using the speed wing ribs, and claimed to have a faster wing then the Stol wing with nearly as good of climb.  

Photo1295.jpg

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Posted

My project did not come with the flaperons so I will need to build those also.  Are there any drawings on file that shows these parts?

 

Thanks

Jim

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Posted

I don't believe there are any drawings available for the flaperons.  Some guys have built them though.  Basicly they are an aluminum tube, foam ribs, aluminum skin, and the flaperon hinges.  JImChuk

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Posted

I think if you are building the ribs you could incorporate the old style flaperon bracket into the new style kitfox 4 wing rib.

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Posted

I think if you are building the ribs you could incorporate the old style flaperon bracket into the new style kitfox 4 wing rib.

I agree with you on that TJay,  but also if he builds the flaperons himself, then the hinges could be modified to fit the Kitfox 4 style hangers.   Of course,  the more things that get changed, the more one is becoming an aircraft designer.   That's all well and good if the design turns out to be good, but what if what seemed like a good idea at first turned out to be not so good later on.  The further we stray from the original design, the more we start to get into uncharted territory.   JImChuk

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Posted (edited)

The Raven, an Avid/Kitfox clone, plans are available online and have drawings of all of the parts necessary to build flaperons.  I bought them and found them (the plans) very handy. 

https://plansforu.com/plans/raven-kitfox-replica-plans/

Edited by wypaul
addition
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Posted

Thanks guys, I will check it out.  Thanks for the info.

 

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Posted

It feels crazy that me on one side of the world (Sweden) is restoring a set of Speedwings and you on the other side is scrapping them. Why do you do that?

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Posted (edited)

After getting the new project home, an Avid mod A, to Ohio, I think I'm going to scrap the old speed wings and build a new set of extended wings. Does anyone have a templet or a tracing of the speed wing ribs that I could borrow or get a copy of? Many thanks for your help.

Jim

hi jim, you can have a look on my mod wing in the avidC section. it is less work than starting from 0 and saving a lot of money; i've not flew bird yet so i can't tell you how it works and give any recommendations. the goal of my mod is : getting away from speed wing trap, match the kitfox airfoil, extend a bit w span but not to much cause excessive washout and small tail of early avids

:BC: manu

Edited by efil 01

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Posted

I am not throwing the old wings away, I am trying to restore/replace with a wing with newer material in it.  The wings I have are not very well assembled.  They look like crap and could use a complete overhaul or replacement.  Maybe just a good cleaning  will suffice. Whoever built the wings got carried away with the spray foam.  I was just thinking as I was trying to clean them up that it would be easier to just replace them with a newer set. 

What are the advantages of the speed wing vs the stol,if any?

Jim

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Posted

Efil01 did a brilliant job combining the best of both wing types.  The problem is nesting the next smaller tubing inside the existing spars since typically this doesn't work with 1/8" diameter steps and wall thickness greater than 0.058".  However, by going to the next  larger tubing size, for the span extension, and 0.058" wall thickness,  you could extend the span out to that of the STOL version.  Bending moment at the joint would be well below that at the strut attachment, so it's safe structurally.

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Posted

hi

thx turbo for your input, to extend spars, i had the big luck to find a metric sized tube that goes perfectly in speeding spar, i had to insert them by gently hit.

as for wing span, i decided to go on a half extension to keep original short flaps and reduce big adverse yaw given by long wings and gain yaw stability with less inertia for the small avid tail

 

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Posted

Just got back from the hanger.  I started cleaning and measuring the wings that I have.  They measure 125" tip to root rib with the ribs being 12" OC.  After scrubbing real hard, I think they might clean up and be usable.  I thought the speedwings were 18" OC and the arobatic wings were 12"?  What is special about the butt rib and what is its purpose?

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Posted

the butt rib is the top stol airfoil cause it has to match the fuselage and false ribs of canopy, so the owner can switch wings with no gap

you can see on files here how wings are made , stol,heavy hauler, speed, aerobatic

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Posted

Manu, that's what I thought.  Metric sizes!  Japowell, if you decide to extend the span, make sure your span extensions are 6061-T6,, 2024-T3, or 7075-T6.  The alloy of aluminum used is important, as some are much stronger than others.  The 3 listed here are among the best.  The original design uses the first one.  It is the weakest of the 3, but is very corrosion resistent, and is safe, as the wings will take a permanent set if overloaded long before they fail.  

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Posted

Thanks Turbo.  When you do the extension, is it usually just two rib spaces or is it more? 

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Posted (edited)

it is usually ( for stol span) 2x18 or 3x12 per wing, perso i made 1X18 and recover lift by airfoil, so kept short flaps ( a bit extended)

Edited by efil 01

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Posted

How much does the flight characteristics change? What are the advantages of doing the extension?  I'am building new flaperons also, so it doesn't matter if I go 2 or three ribs.  What will each give me?

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Posted

engineer turbo will confirm :)

but i guess you gain  lift because more suface, and lift because  more reynolds number due to new wing span;

fast calcul for complete extension :

wing area is approx 4/3 more so you will gain minimum 1,33 more lift.But it is not completely true because washout reduces lift but on other side with more  stability at the edge of stall

i guess you to not going longer than standard stol wing because it will change the max momentum at the wing strut liaison, and spar may not support new flexion at Gs avid is certified for. And the tail will not assume whole control if wing area is to big.

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Posted (edited)

I've got to agree with Manu here.  It would be dangerous to go beyond the span of the STOL version without a stress analysis.  In my opinion, the STOL version's airfoil has too much camber, which conspires to limit top speed.  I'm not the greatest tailwheel pilot, and am thankful for the lower landing speed with the greater span and area of the STOL  Camber does not translate directly to max lift and low stall speed, but more wing sure does.  I think you're nicely set up to get the best of both wings, cruise speed closer to the smaller speedwing, and a lower stall speed for easier landings, and improved safety if you ever need to make an outlanding when the prop stops turning.  If you have the tri-gear config, or lots of tailwheel experience, and see your bird's primary mission as getting from A to B, and fly in a place where there are lots of good spots for emergency landings, maybe the speedwing is your ticket.  This is what's so great about experimentals!  Of course, we'd all love to see some pics!

Edited by Turbo

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Posted

Another issue that may come up if you make the wings real long, is the flaperons may start to bind.  The longer the wing, the more the tip will be pushed up when under load.  That will also bend the flaperons.  Chris B cut his over length fat Avid wings back because the flaperons would bind in flight.  On the Kitfox 3 and later, the lift struts attach further out on the wing then earlier models, and I suppose Kitfox did that to take care of the increased flexing in the wings as the gross weight went higher.  JImChuk

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