How To: Sonex - Build it light?

[DavidLawson]

Greetings all,

I am sure I am not the first, or the last to ask this; however, I have not seen a thread on the subject. A builder told me there can be quite a bit of weight saving's that can increase payload/range if I "build it light". Aside from a lighter power plant, or leaving off paint, the conversation sort of ended here. I plan to build a sonex with floats and to make it corvair powered. This said, I wonder (having not seen plans) where such weight savings could be had. In my hot rodding background we would use thinner gauge aluminum and rib it with an english wheel, we would also swiss cheese parts of the frame and the like. Something on the ground with air bags is vastly different than an aircraft. I just don't know how such a thing could be accomplished.

Forgive the redundancy of the topic if this has been covered.

Respectfully,

David.

[falvarez]

I personally wouldn't touch the structure. But you can build lighter fiberglass parts, choose a newer panel w/o analog guages, and you already mentioned no paint. Those are the obvious things I can think of.

[Bryan Cotton]

If I was scratch building and wanted to trim weight:
Carbon fiber instead of fibeglass
Titanium firewall instead of stainless
Minimal avionics

That is about it. I would also not mess with the basic structure.

[DCASonex]

Key to building "light" is not so much reducing weight of the basic design as it is not adding to it. Decide what is important to you and add ONLY that. I have one of the heavier Sonex, with a lot of goodies but it was built to carry a couple of old farts cross country in some degree of comfort and does that very well. (And with a CAMit 3300 up front still very potent performance and a blast to fly when just want to yank and bank.)

David A.

[Pickleman]

Jeremey had a great webinar that detailed how the factory prototype gained around a 100 lbs (IIRC) through all of the little things we do to make flying more comfortable. Corvair is probably the HEAVIEST option for 100 ponies on the nose. Floats are probably the heaviest landing gear. What is your flying mission? What are your goals? The Sonex may not be the plane to fill them.

[radfordc]

Greetings all,
I plan to build a sonex with floats and to make it corvair powered.

David.

That ought to make a very nice one place airplane.

[kevinh]

Speaking on this thread: Anyone able to provide a rough estimate on paint weight for a full one color (white or yellow) paint job on a Sonex? (Just for my guessing/planning purposes) 30lbs?

[kmacht]

Based on the weight of the paint I started with and what I was left over with I was somewhere around 25lbs for my paint job.

Keith
#554

[wlarson861]

I think the factory said about 14 pounds to make theirs yellow as opposed to polish.

[SonexN76ET]

David, If you are serious about the floats, see if you can look up the tail number of the Sonex on floats and then look up the owner and find out his experience with operating on water. I am sure it would be a blast! If you can't find him, I am sure Sonex could put you in touch with him.

As far as building light, a stock Sonex is incredibly light already. Like others have said, substitute carbon fiber for fiberglass, use light weight cushions for the seats. For a sea plane in Florida, you will have to paint and use corrosion protection. However, the paint will be around 13 pounds. Even if you put 25 pounds of paint on it, you still have some over spray and evaporation.

Some things in construction to build the lightest weight airframe would be to go with the flush rivit option. Use AAP aluminum rivets on the tail tips and wing tips.

Also consider the turbo Aerovee instead of the Corvair. I believe the turbo Aerovee is lighter.

Make sure you go to Sun N Fun in April in Lakeland, FL and visit the Sonex display with the Sonex turbo.

Jake