As far as I know the turbine version of the Cri Cri is still going strong. Range is the only problem. It is pretty light and doesn’t seem to suffer too much from lag.🙂
It does only work as an UL in Annex II – operating it as a cerfified airplane (even if it was certified) under EASA rules would be a nightmare…
Reading an article in flyer – Elixir and Bristell are also working on this turbotech option – tellingly Bristell have said its a project plane – I think they expect the cost premium over the rotax 915 and the immaturity will make it a hard sell.
I would really prefer to be burning kerosene, with a modern fadec, but its only the ULM rules on weight that makes this turbine viable – otherwise you would install the cd-135 engine from continental – proven design – cheaper than this turbine and it has even better fuel specifics.
Malibuflyer wrote:
I’m not exactly sure if it is the very best idea I ever heard to combine the low weight and thus inertia of a microlight with the intrinsic lag when adding power of a turbine.
I don’t see where the lag should come from. At constant rpm, all you do is inject more fuel. There is nothing to “spool up”. Turbine helicopters don’t suffer from any lag as far as I know. A turbojet on the other hand is another matter. I would think fuel burn at low power would be rather insane though, unless lowering the rpm, which would make sense in cruise, but not during take off and landing.
If they manage to get this to really work in real life, it for sure would be cool 
130 hp and 80 kg is very similar to a piston. Which is good perhaps, the same airplane can easily switch between piston and TP with minimal modifications. This is insanely cool actually I hope they make it work.
Turbine Helicopters suffer from this lag much more as the inertia of the rotor adds to the lag of the turbine.
That is exactly the reason why helicopters do not control altitude by rotor RPM but by blade pitch (very, very simplified) and regulate power/RPM more slowly.
ALL turbine engine lag when accelerated, or decelerated. And so do piston engines and props…
The simple reason is mass. More fuel for more power = mass acceleration to the required RPM. This evidently is even more pronounced with multi-turbine/compressor with multiple stages. When an N2 turbine is producing power, it is directly linked to its compressor, but only indirectly linked to the N1 compressor, which in turn is producing the real thrust, as in ~ 80%+ in modern engines. Some companies such as R&R even produce 3 rotor jet engines.
Even the small RC turbines as used in the RC world (and the Cri-Cri) show some lag.
The 200k+ ULs sell in very small numbers, mostly to guys who want an expensive toy, so putting in a turbine is a perfectly sensible idea It doesn’t have to have a 2000nm range.
Peter wrote:
so putting in a turbine is a perfectly sensible idea
That turbine looks like a “perfectly sensible idea” for most ULs I’m afraid, as well as several experimental homebuilts An RV12, RV-9, even the -4 would be perfect with a 130 hp turbine. Not to speak of my Onex and all other Sonexes.
What is there not to like? A real turbine. Jet fuel everywhere, the right weight, the “right” power, the right sound. Fuel consumption in cruise less than 20l per h. The price tag will be around €50-100k is my guess. This will calm things down I would think. It has a heat exchanger. Will that last for the TBO of 3000h ?
I’ve heard from a good source, that JMB will introduce the VL3 with the new Rotax 316 at the Aero in Friedrichshafen. What does JMB want with that? Isn’t it just a pure overkill of engine power for a UL? Or are they finally gonna certify an EASA-VL3?
They do it because people will buy it, because more is always better :)
I think even the 915 is an overkill for an 600kg plane, but i heard that most VL3s are ordered with the 915, so from now on most will go for the 916, just because they can (except France, they still have the 100hp limit on ULs)
I think a modern 914 (EFI, FADEC) would be the best fit for a Aircraft like this, but who am i to judge ;)
