AVID C ready for registration, need drawings

11 posts in this topic

Posted

Hello folks, my 10 year build of an Avid C, STOL wing,  Serial #335, is finally coming to an end. The first thing I did when I started work on the barely started kit was to stretch the fuselage the 16".  So I guess that the profile and plan drawings that I need for FAA registration would actually be Mark IV drawings, correct?   I'm thinking I'd have to square up the rudder on the drawings, but other than that they should work, no?  If anyone has that page of the manual readily available and could email it to me I'd really appreciate it.   I put a Hirth 2706 65hp engine in it. The engine came with a 3.65/1 PSRU, and Powerfin convinced me to put a 4 bladed prop on it because of that big reduction.   It's a ground adjustable prop, should climb like crazy, and I'm more interested in low-n-slow than speed. The info gleaned from these pages has been invaluable, I can't imagine completing this build without access to all of your experiences.   Now I've just got to get my Sport Pilot's License!  I'm looking for instruction somewhere in the Northeast or Mid-Atlantic.   I started lessons near here (VT), but the Cub I was training in crashed.  The student and instructor were OK, but it shattered my faith in that flying school.   Here's a picture of my plane:

20170521_130958_001.jpg

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Posted

Looks nice!  It is a great achievement to build an airplane, so good on you.  I don't believe the dimentions on a C model and MK IV are different.  Maybe just change the dimention on the length on your drawing to reflect what you actually have.  Doubt that anyone will complain.  Or better yet, ask the DAR who will inspect your plane to issue it's airworthness certificate.  He is probably going to be the only person who will look close at it.  I'm curious how your weight and balance came out with the stretch and the light motor on the front.  Probably you are aware of this, but you can't train in your own plane until the phase 1 flight test hours are flown off and it is moved into phase 2. At any rate, congratulations on the build.  JImChuk

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Posted

Mike,

I think the simple 3-view drawing could be made by using a regular C model sketch, and photocopying it, cut and paste the stretch into the top and side views, and copy that new version. Be sure the dimensions match what you built.

Beautiful airplane, BTW! Nice job.

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Posted

I don't know if it's me but that prop looks HUGE for the misery 65Hp engine....I know that running a slow prop speed the diameter has to be increased ... but to have a 4 bladed prop and such a big size diameter (looks like 69in) seems over proping the poor hirth

fantastic looking aircraft .

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Posted

I don't know if it's me but that prop looks HUGE for the misery 65Hp engine....I know that running a slow prop speed the diameter has to be increased ... but to have a 4 bladed prop and such a big size diameter (looks like 69in) seems over proping the poor hirth

fantastic looking aircraft .

Is the Hirth gear box that much stronger than the Rotax gear box? The prop manufacturer usually know how to get the most out of their props on a given horsepower and range of speed desired; I'm wondering if they run this by Hirth before recommending it? If so I'd say it should climb like a home sick angel.

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Posted (edited)

Thanks for all the support.  I'll take your advice and ammend a C drawing.    But I still need that  3 view drawing of the plane (top, front and side) that I can redraw,  I didn't get one with the build manual that I got.   I know I've seen one somewhere, most likely on this site.   I thought it would be in one of the manuals, but now I'm having trouble downloading them to look again.  Can someone please direct me to the right place to find one of these drawings, or email me the drawing?   It'd really be appreciated. 

On the prop question, it must be because of the huge reduction that Hirth and Powerfin recommended the 4 blade prop.  I first set the pitch at 15 degrees and the engine wouldn't rev above 4500.  Next I repitched to 13.2 (was shooting for 13, but came in a tad high) and the engine would max out at 6200.  Hirth recommends 6500 rpm max, so I think I'll leave it where it is for now and maybe tweak it later if I want. 

Edited by MikeRSawyer
forgot something

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Posted

You can find the drawing at the link I will post down below.  Look at the first PDF file, the drawing you want is about 6 pages in.  As far as the prop static RPM, if you are turning 6200 static, the rpm will increase when you level off so possibly the 6200 is about right for now.  JImChuk

www.avidfoxflyers.com/index.php?/topic/1927-avid-builders-manual-and-ads/
 

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Posted

Thanks much Jim, I've got the drawing and am giving it the 16" stretch.

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Posted

Nice looking airplane Mike, congratulations!

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Posted

Nice looking bird.  I read comments on here about stretching the early Avids.  I am getting ready to do that to my model a.  Does anybody have any pics of them doing this?  If so, I think the group would like to see somee.  I know I would.

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Posted

Interested in how the 65 HP Hirth does. I am using the 55 HP 3202 on my model 2 with a 2 bld 70" WD.

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