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Ultralight Construction Advice

Posted By:
Ben Anderson
Homebuilder or Craftsman
7
Posts
0
#1 Posted: 1/15/2011 12:50:17

Being a new member and just purchasing my first aircraft last summer, I have a couple questions ranging from protective wood finishes to engine options. First, the aircraft which I bought is a Ragwing Parasol, it's probably half way completed. I bought it off of a guy who couldn't finish it and so I benefited off of his misfortune. Out of the 22 required ribs, 11 of them are completed, the fuselage is pretty much done, the landing gear is done, and some other odds and ends are already in place. Now on to my questions. Which is better, a built up spar or a solid? A lacquer finish, a spar varnish, or an epoxy varnish? Is a butyrate coating better then any latex paint? Finally, what type of engine is better, an aircraft quality or a standard gasoline engine? Thanks for your time.



Dana Hague
29
Posts
2
#2 Posted: 1/17/2011 11:57:38

 

"Which is better, a built up spar or a solid?"

It depends.  A built up spar can be lighter, and just as strong if it's properly engineered.  If you're building to plans or a kit, you should use what the designer intended, unless you're prepared to completely re-engineer it, and perform appropriate analysis.

"A lacquer finish, a spar varnish, or an epoxy varnish? Is a butyrate coating better then any latex paint?"

I can't help you on the varnish but a butyrate dope finish is probably "better"... but it will cost more and be more work.  Some people have been happy with latex finishes, others have not.

"Finally, what type of engine is better, an aircraft quality or a standard gasoline engine?"

Again, it depends.  For an ultralight, a certificated aircraft engine will be too heavy.  Ultralights typically use 2-stroke engines which usually are less reliable than 4-stroke engines, but with proper attention they can be adequately reliable... and they weigh much less for the same amount of power.

 



Ben Anderson
Homebuilder or Craftsman
7
Posts
0
#3 Posted: 1/18/2011 09:31:03

Thanks for the advice. A note about the spar, the designer recommend a built up spar due to weight restrictions, however; talking with some fellow homebuilders, most recommended a solid spar.



Kurt Satter
Homebuilder or Craftsman
2
Posts
0
#4 Posted: 1/18/2011 12:03:31


Finished-1103R.jpgI completed a MiniMAX 1103R that has the same wing (according to Roger Mann of Ragwing).  The design uses the built up spar is eaily built and is lighter.  I used marine spar varnish throughout and am ver happy with the latex paint finish (also cheaper).



Ben Anderson
Homebuilder or Craftsman
7
Posts
0
#5 Posted: 1/20/2011 15:35:42

Looks really nice. What type of engine are you using? The plans that I have recommend a rotax 447, I kinda jumped at the price of some these engines and therefore I'm looking for something that is a little less expensive and uses standard car gas. My only reason for standard car gas is that I plan to put a lot of hours on this baby and I really don't want to pay a lot for fuel. Thanks for the feedback.



Kurt Satter
Homebuilder or Craftsman
2
Posts
0
#6 Posted: 2/9/2011 12:14:04

My MiniMAX has a Hirth F33 with electric start.  The 28HP is just fine swinging a 3-blade IVOprop.  I run her on high-octane auto-gas with a 50:1 mixture of the Blue-Max,2-stroke oil recommended by Recpower.

I covered it with the Dacron that was provided in the materials kit and after much reading/research, I painted her with 2 coats of primer sealer and two coats of color, Behr (from Home Depot), latex, high-gloss, exterior, house paint.  Pretty in-expensive and easily applied with a roller.  She's hangered here in North Texas ... finding hanger space was actually the toughest part of the project.

I sealed all of the wood structure with a couple of coats of marine spar varnish from the local Sheman Williams store.  If I remember correctly it was about $45/gal. 

I went all-out with $100 in pre-WW-II era (star-ball) decals from Decal Zone to make her look sharp.

 

 



Phil Schaefer
1
Post
0
#7 Posted: 2/9/2011 20:28:03

Congradulations!  can you tell us what aircraft it is exactly?

The rotax 2 cycle engines use regular car gas.  The 92 octane in the manual is based on different rating system than used in the US and is equivelent to 87 Octane here.

I wouldn't recomment Butyrate to anyone, way to flamable for me.  But I would recommend sticking with a proven aircraft fabric finishing system.  If you're worried about toxic chemicals check out Stewart Systems.  No toxic fumes, and easier to apply than Stitts Polyfiber, but you have to be more careful about oil and wax contamination when applying the color coats.