Could someone check something for me please?

[mcsmarket 0]

As in the picture attached if someone has a C or even a later model would you hold a framing square against the door post and measure the distance from the tip top edge of the square to the bottom of the front spar? 

I'm setting my dihedral and would be much appreciated. Thanks.

 

 

Edited 13 Jan 2023 by mcsmarket

[akflyer 1427]

only 1 end is adjustable on the avid so the front strut sets the dihedral and the one adjustable end will allow you to rig it for hands off flying should it be needed. 

[akflyer 1427]

only 1 end is adjustable on the avid so the front strut sets the dihedral and the one adjustable end will allow you to rig it for hands off flying should it be needed. 

[mcsmarket 0]

Thanks!

Yes, I have my struts and attach brackets made I understand that the rear end is adjustable I was interested in having someone with an Avid check the degrees of the dihedral either with the fuselage level and then say a 4 ft level and measure the space to the level and the underside of the front spar or...even a framing square against the door post. Curious about what that would be on a flying Avid. 

Thanks,

Mark

[1avidflyer 1983]

If you have your manual, you should be able to find the dimension for locating the lift strut brackets on the wing spars.  I'm not close to my manual right now.  Now that I think about it though, the manual is in the files and forms section.  

PS  I just looked in the online manual, and found the info you maybe need.  It's in section III,  chapter 2,  drawing # FW-1B.  There is shows that the dimension from fuselage end of spar to center of liftstrut attachment bolt should be 80"

Edited 12 Jan 2023 by 1avidflyer

[mcsmarket 0]

Thanks!

This plane is scratch built, from what I have researched, the distance from the root end of the spar to the attach bracket bolt hole should be 80" yes. Nowhere can I see what degree of dihedral there should be on the Avid. The Kitfox calls for one degree.  If I go the 80" it looks like too much, I'm at 84" with one degree. That's why I'm curious about what the Avid is at in degrees?

Edited 13 Jan 2023 by mcsmarket

[1avidflyer 1983]

The figures I gave in this post were incorrect and so I deleted them and corrected them in my next post. 

Edited 13 Jan 2023 by 1avidflyer

[TJay 1041]

I have my kitfox set when I measure out 12 foot from root end I am 2 1/4 inches higher Hope that helps.

You may have longer wingstruts if its scratch built.

[1avidflyer 1983]

I got to thinking after I went to bed last night, and remembered  pulling a string from wing tip to wing tip and as I remember, I had 3 or 4" to the skylight.   Went looking for pictures of my Avid MK IV, and found this.  I'll see if I can find pics of my other Avids, but I don't think this one has more dihedral than the others.   

PS Last night I posted some figures on what one degree at 80" would add up to. Today, I got to thinking, and realized I was mistaken in my figures. The lift strut attachment bolt is 80" from the end of the spar according to the Avid wing build manual. But if one was going to figure out how high the bracket should be at a certain degree, you need to double that 80" figure to get to the diameter and then multiply that by pie (3.1416) The figures I posted last night used the 80" length, so they were off by 1/2. Therefore, (unless I'm wrong again) 1 degree at the liftstrut bracket (80" from the butt end of the spar) should be 1.396". At 4' that should be .837" Hope this helps and no one read my previous incorrect posts.   So,  80' X 2 = 160"  X 3.1416 =  502.65  (circumference of the circle)  divide by 360   (number of degrees in a circle)  = 1.396"

Edited 13 Jan 2023 by 1avidflyer

[mcsmarket 0]

Thanks guys! Nice to have people to bounce this off of, it's been a lot of years building. I've enjoyed the process and it's getting really close!

1avidflyer, I used a trig formula 80tan(1) on the calculator I found awhile back and came up with exactly the same 1.396. Then looking at pictures and videos like your picture it looks more than 1 degree. With TJay's comment on the Kitfox that would be close to 1 degree so it looks like the Avid maybe had more dihedral than the Kitfox. Noticed also that the attach points are more center of the wing on the Kitfox and I have ended up with longer lift struts for some reason. So I have a decision to make. I'd like to try the level string and see what I end up with in the center of the fuselage, can use my laser level.

See skis in your picture 1avidflyer, I just received my UHMW-PE with UV protection to build a set so more work.  

[1avidflyer 1983]

Here is a post where I show a bunch of my ski build pictures.  Making a new set of skis - Forum How-to's - AvidFoxFlyers Forums

Back to the current topic, can you measure the front of your lift struts, and post the measurement?  I can't get a measurement just now, but maybe some one else can.  If you have a different length, that would explain why the 80" measurement isn't working for you locating your lift strut bracket.  

PS  Just rethinking things, and remembered you said the plane is scratch built.  There never were any plans for Avids that I'm aware of, but someone did copy the Kitfox 1 and made plans from it.  Called a Raven I believe.  Maybe you would find that the measurements for a Kitfox 1 might match up better with what you have.  I know there is also a Kitfox 1 manual in the files and forms section.  I had a Kitfox 1 and have the measurement for the lift strut on it, and that is 98" from center to center of the front lift strut bolt to attach point bolt on the fuselage.  

Edited 14 Jan 2023 by 1avidflyer

[TJay 1041]

Model 1 length is the one on the floor vs Model 4 length installed not sure how it compares to yours.

[1avidflyer 1983]

TJ,  I see you have a different dimension on the Kitfox 1 strut, but noticed that yours is the rear tube of the lift strut, mine was the front tube at 98".  The more info he can get the better, to try to figure out what he has.  (why isn't there a thumbs up in the emoticons?)  

[mcsmarket 0]

I really appreciate your time on this guys, you definitely have a passion for building. In Canada here we're kind of lucky in that our basic ultralight rules are 1200 lbs gross weight and if we build from raw materials and various aircraft components, we are deemed the manufacturer. I have my plane registered and have my marks now.

Originally bought Kitfox gear and a 582 motor mount from a guy who was changing those up have the fuselage and wing dimensions from a plan called the Mohawk similar to the Raven. 

So here's what I have in the attached pictures, the 6'-6 (78") level showing 1-1/2" in dihedral, the two measuring tapes with those dimensions plus the Kitfox jury strut looking pretty fair and close to where it should be plus the planned 2" washout planned for the wing. I went about building the struts after rigging the wing using it as a jig.

I can get more dihedral by sliding the attach brackets. That's why I was asking about the amount on the Avid. All variables considered in the end the dihedral and the sweep in the wings is what shows up. I have a string set up showing the wing straight with the fuselage. 

I'd also like to have the struts more centered on the wing much like the modern Kitfox, Have extended my tube spars the 18" rather than use the Avid wing tip design. I'm going to angle the tips upward like my Zenith CH 300 has which cuts down on wing tip vortices. 

[mcsmarket 0]

The front part of the strut is 8ft in length and the attach bracket to the mounting hole is 84-3/4" from the butt end of the spar. Also have the thicker wall spar tubing .083 rather than .065.

The picture is my own design of spar stiffeners, didn't want to use the wood.

 

Edited 15 Jan 2023 by mcsmarket