one would hope he got the offset the right way round.
I would even go so far as to say “we may trust…” After all there 13 of them on the G-register alone (cfr G-INFO), there must be far more in France, not even mentioning the rest of the world; yet I find no mention of a single crash of the type. Though a non-fatal incident might well be kept from the media, still it seems the type is quite safe. No surprise of course, if one knows the designer. It is not his first design, not by a long way. We really may trust him.
Well, I certainly thought quite hard about things prior to buying the plans, and everything I heard about Mr Colomban lead me to expect the type to be well thought-out.
I’d still be interested to hear any thoughts – e.g. was there anything else you didn’t like about the design LeSving? I know the main wing spar (carbon/wood) is a little controversial too. As Jan points out there are enough flying now that you might hope any major issues to have been uncovered. I worry a lot about engines, primarily because I’ve never owned an internal combustion engine in any form, and simply don’t feel I know much about them. And because I have had problems with spark plugs fouling so do wonder whether a single-ignition engine with dual cylinders can really be said to be a good idea.
Ideally I would have looked for an aircraft that might potentially be flown night VFR and in light IMC, because part of what I want is an aircraft that I can afford to fly sufficiently to keep current. But realistically I’m not sure what the new UK permit rules allowing IMC are going to look like – suspect it will be restricted to types that were previously certified for IMC that now operate under a permit. And I would probably want to have at least a Lycosaur/Rotax by which time you’re talking about much bigger, more expensive aircraft.
It’s probably a good design. But that B&S is heavy and weak on power. The SD1 flues well with the B&S also, but even better with the 50 HP Hirth or the Verner. The designer of SD1 said he prefers the Kohler, being more reliable and more powerful than the B&S. Igor Špacek, the designer of SD1 also flues them, builds kits and test different engines and options. I have no Idea what Colombian does, for him it’s just a paper design? Igor has also done design work on several other commercial designs.
If you do not know what Mr Colomban (sic!) is doing you may learn a couple of interesting things through a little bit of www research. And do be assured he is very much a hands-on type.
Regarding the choice of engine: for reasons best known to himself, Mr Colomban wanted a four-stroke. In this power range, these are rare; while there certainly are lighter 2-stroke engines available, and I think it should not be impossible to install one – though the weight and balance on this fragile bird must be a delicate exercise.
I’m sorry for the spelling. Used my phone in something as unusual as sunny weather here 
I maybe should check out this Colomban, but if he is French, then it’s probably all in French, so it will be impossible anyway. The SD-1 can have any engine within certain weight and power limits. Spacek has made 5 different engine kits: B&S Vanguard 24 HP, Hirth F-33 28HP, Kohler CH-750 31 HP, Verner JCV-360 35 HP and Hirth F-23 50 HP. Each engine with characteristics in the airframe can be found here.
A direct drive low rev 4 stroke sounds “right” for an aircraft, low rumbling with lots of base , but that is really all. Both the B&S and the Kohler have cast crank shafts for instance (as far as I know). A propeller mounted directly on a cast crankshaft is an extremely bad idea. Here it works somehow, because they use lots of steel, but for how long? To think for a second that the B&S or Kohler are a better aircraft engines than the Hirth F-23 simply because they are 4 stroke, is nonsense. The F-23 is a better engine in every respect. An aircraft sells better with a 4 stroke engine than a two stroke engine, and that is the only reason they are included.
Colomban is also the designer of the Cri-Cri, so well known for his ultra lightweight designs. Link
Along the same lines but going back 35 years, I’d like to fly a Quickie with a more modern ultralight engine. They’ll cruise at 105 kt with an 18 HP Onan generator engine. I’d imagine with 40 HP from the same weight engine, the Quickie would surely be a rocket ship They have one in the Deutsches Museum. Link
OK, Colomban is one of the great by the looks of it Thinking about that spar. It is maybe more of a structural thing than an aerodynamic thing. You add a twisting moment to the inner most fuselage/spar structure that wouldn’t normally be there on a symmetric design. The twisting moment or torque is of the same magnitude as the bending moment of the entire wing affecting the spar. It only affects 1 inch of the fuselage/spar structure, but it is still there and must be accounted for. But when the aircraft weighs only 100 kg, I would think this is very easily accounted for by simply using one size larger bolt (assuming the wings are removable and bolted). Still, it leaves an impression of sloppiness and it does not look good.
The aircraft does look cool though. There is something irresistible about super-small and super-light aircraft
First post here for me but my interest was piqued by this thread.
I have always rather liked the Luciole. I don’t have one and have never flown one but I think you guys might be over-thinking this.
Given that M Colomban is, by all accounts a competent, accomplished even, designer of light aircraft my guess is that designing it so that the wings are longitudinally offset by the spar width was done entirely for simplicity, and simplicity often translates to lightness, a parameter high on his agenda in designing the Luciole. I’d further guess that he conscientiously determined that there would be no noticeable detrimental effect resulting from that design decision.
My Vans RV12 also has offset spars to allow quick wing detachment, but the wing is made symmetrical by having differing length front and rear ribs on each side of the aircraft.
I never doubted Mr Colomban – just thought it was an interesting design choice and wondered whether it was common or whether I had misunderstood.
Different length ribs I find a whole lot more surprising – the aeroelastic properties of each wing will presumably be quite different. I had been under the impression there was a lot of science behind how you chose to site the wing spar. But then, the RV designers have a good track record too.
