AF wrote:
In layman’s terms (for those like myself), if the length and shape are the right balance for a given velocity, the recoil of the air from being compressed at the nose is utilized as it expands toward the tail.
Thanks to your and LeSving’s information, I think I get the overall concept now a bit better :) Correct me if I draw the wrong conclusions, but it’s similar to the idea behind pressure recovery shape for e.g. wheel spats, additionally helped by the propeller at the back.
AF wrote:
I’m also not sure about this. In theory it does work, but in practice, the airfoil must be absolutely defect free, which is extremely difficult to achieve.
I’m having my doubts that maintaining a highly smooth fuselage and airfoil is practical from a daily live perspective. I’m wiping down the bugs from the RV-7 after most flights, but even if there’s some dirt on it, the fat NACA 230 series wing will exhibit not a lot of increased drag; if I need to keep the big tube of the Celera clean and smooth, I need to pay my nephews a lot for waxing and polishing every week ;)
One other thing I wonder about is the engine. While it actually has achieved type certification it seems to be quite heavy already in dry state (360 kg) compared to a low-powered PT-6 (about half the weight or maybe a bit less). So you get a bit better SFC, but with a massively heavier engine and the additional hassle to deal with the coolant system, intercoolers, multi-stage turbos, etc. An advantage that I could see is that you do not need a turbine class rating, but is it worth it really?
@Sebastian_H
To my understanding it is exactly like that, and the prop actually is used to increase the effect, as it creates a decrease in pressure forward of the prop blades, thereby magnifying the effect, and, in combination with the shape of the fuselage, the lateral pressure coming back into the void against the fuselage contributes thrust…
The cool thing about a laminar flow structure is that the bugs will only collect on the front of the airframe. So cleaning will be really easy, as it is basically just at the very nose of the craft.
Two big concerns for me are the ground clearance (looks like 8" or something) and the complete lack of windows in the passenger section.
Unless that little square in the middle is all they get. Reminds me a bit of Zoolander’s center for kids who can’t read good.
What is this, a window for ants?
What would be the engine failure on T/O effect on certification for commercial use?
What effect would propeller failure have on handling, if it has that effect on drag?
The fuselage/prop arrangement follow a design that I read about some time ago. The idea is that the fast revving prop sucks the boundary layer back on the skin, resulting in laminar flow.
But what you gain on fuselage drag you pay for in prop efficiency – seems pretty obvious from the layout and the „stuff“ ahead of the prop.
Very curious to see real world data…
On their website, as well as on engine manufacturer’s website, we can find the claim that the engine has a ‘redundant setup’..
they create the idea that this engine is in fact two engines.
It is completely beyond me how that would work, given that all 12 cylinders are working on one crankshaft, have one oil cool system, and only one fadec unit.
Does anyone know more ?
EuroFlyer wrote:
It is completely beyond me how that would work, given that all 12 cylinders are working on one crankshaft
Maybe designed by the same idiot person who put 2 magnetos on one drive shaft?
Not really comparable, because
Not saying it is a good thing at all but statistics don’t really support the often cited “it’s terrible” position.
Whereas there are loads of single point failures in a piston engine. One can’t even rely on a cylinder failure being tolerated; unless it is just an ignition issue (unlikely to get that just on 1 cyl if you have the usual dual ignition) the engine usually disintegrates fairly swiftly, and even if it manages to hang together all the oil will soon be lost.
We’ve had two concurrent threads on the Celera; I’ve just spent a while merging them 
EuroFlyer wrote:
It is completely beyond me how that would work, given that all 12 cylinders are working on one crankshaft, have one oil cool system, and only one fadec unit.
It’s actually not such a far-fetched concept at all: My old 70’s V8 behaves basically as two independent inline-4 engines sharing a crank shaft. Each bank has a separate distributor and coil, and each cylinder is quite independently supplied via a separate barrel of the set of four dual-barrel carburettors (Weber DCNF). I had to deal on one trip with an ignition problem that basically took out one distributor and the engine ran along on one 4-cylinder bank quite alright until I could get to a mechanic. It helped of course that without a catalytic converter the surplus unburnt fuel more or less went out the exhaust, but for an aero engine I could imagine that it would be alright as an emergency mode.
As far as I understood the Celera’s engine, with redundant FADEC and multiport injection you could lose a bank completely as long as no obstruction inhibits the crank shaft from turning; Of course there will be losses due to moving an inactive set of pistons around.
Edit: In case of more dire mechanical issues with one cylinder or bank, it all depends how much it inhibits the other bank from moving. In less problematic cases, you still have emergency power from one bank to get you more controlled down.
What is astonishing is that usually, you don’t test a brand new aircraft design with a brand new (and original) engine design.
At 65000ft, the pressurization will suck quite a lot of power from the engine, won’t it ?
There is no ground clearance requirement for certification ? At least, if a wheel falls into a pothole, nothing happens
And max pitch at rotation/flare is 0,5° 
Sebastian_H wrote:
Of course there will be losses due to moving an inactive set of pistons around.
