a Sonerai III ?

[KWK]

Digging through a box in the closet, I came across a II-LS(T) plans set I bought in 1993. I thought I'd given those away about 20 years ago. Looking over the plans I see an admirably simple airplane.

I'd have to make some adjustments for headroom, but I could probably fit in this thing. However, I quite prefer alongside seating to tandem. So: Has anyone ever built a Sonerai as a tube and rag Sonex?

The plans show a cabin 22-1/2 inches wide between longerons. Snuggling up with the wife with a slight seating stagger suggests we could get by with 34-1/2 inches. That's a cabin stretch of only 12 inches.

Comments solicited,

Karl

 

[VenturePilot]

While this is the true spirit of experimental aviation, why not just buy Sonex plans and scratch build one of those?

 

[KWK]

Because I already have the Sonerai plans? Of course, I also have the Tailwind plans which I purchased from Wittman the same year, and which lead me to forget about the Sonerai plans. Some rides since then in low wing airplanes have made the Sonerai tempting again.

Okay, I admit it's mostly just for the sake of "what if."

 

[TFF]

You have to strengthen the spar in the cabin. It’s longer, so now it’s weaker. Lots of drag added, but that may be an acceptable trade. Still tight.

 

[BJC]

Comments solicited,

Do you want to design or fly?


BJC

 

[Tiger Tim]

I’m guessing it would be a little bit slower and a little bit heavier but if that’s worth the trade it could be a unique little airplane.

 

[TarDevil]

I always thought, "One of the coolest and affordable tandem planes."

I think it would loose it's charm if changed.

 

[Marc Bourget]

If you desire more room, consider "scaling up" 10%.

IMHO, the thicker wing will gain strength more than the additional weight will detract.

 

[Victor Bravo]

Do you want to design or fly?


BJC

 

[mcrae0104]

Comments solicited,

Karl

I say go for it. Looks like a fun project.

 

[KWK]

You have to strengthen the spar in the cabin. It’s longer, so now it’s weaker. Lots of drag added, but that may be an acceptable trade. Still tight.

The carry through spar looks to be loaded in bending only, so the length affects only column buckling of the top and bottom members of the spar. One should be able to do that calculation pretty easily. Come to think of it, I have a copy (probably loaded off this web site) of a design manual (circa 1940) for 4130 tube. I imagine there will be a little extra moment from the increased flow over the wing roots as they catch the extra flow deflected laterally by the wider body.

Actually, I'm more worried about the CG. With the II-LS, that 40% spar location puts the torso of the passenger close to the CG. Given the tiny tail on the Sonerai, managing the CG has to be important.

I agree, it's still tight, but all Sonerai are tight, aren't they?

I'm not convinced about the drag. Comparing the specs for the Sonex and the Sonerai II series, it's not a huge difference in performance. Ditto the RV-7 and the -8. Those cheeks covering the cylinders on the Sonerai look pretty draggy to me, and they'd disappear into a wider main body.

 

[KWK]

I say go for it. Looks like a fun project.

Thanks for the visualization. It was only in my mind's eye before.

 

[TFF]

CG is easy to figure the distributions. You know what the stock one is suppose to handle. Put stuff where you want it and see what needs to be moved and if it’s possible.

As someone said on another forum, a cowled Lycoming 360 will be 39” l, give or take, because the engine is 34” wide. The cowl width will dictate how easy it will be to get away with it with simple aerodynamics. What are the proportions of the Sonex? It’s going to be close.