There were some combo planes that had both wing mounted and tail engines; DC-10 and L-1011 come to mind

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And then there is this:



https://www.youtube.com/watch?v=AraV2kvytIY

Looks like a harmless polyp. Simple to remove and send off to see if it is benign.

no, that's a testbed (by honeywell (and probably PWC) it looks like) ... for developing the engine software and performance.

another day in paradise, or is paradise one day closer ?

This is the old version: https://historicalcenter.embraer.com/global/en/cba...

Ahh, an answer to the question "What's the vector, Victor?"

If nothing else, it complicates ground support access between the wing trailing edge and the props.

From the state of the wing, it looks like a very low maturity concept still.

rb - yes, Boeing had a concept like this in the late ‘80s, the 7J7. Fuel prices dropped and there was no market for this, so it was abandoned.

Bit of a thin looking wing in that top photo.

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Also: If you get a response it's polite to respond to it.

I thought one reason Boeing dropped it was that the prop didn't like being in the wing downwash ?

another day in paradise, or is paradise one day closer ?

Maybe they should be mounted on top of the tail then?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

why not on the wing, as the great designer intended ?

another day in paradise, or is paradise one day closer ?

Ahhh... the Ultrahigh By-Pass Un-Ducted Fan engines... lovingly known as the 'screamers'.

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Quote:

Ahhh... the Ultrahigh By-Pass Un-Ducted Fan engines... lovingly known as the 'screamers'.

That's my recollection why they didn't catch on at the time.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

Flight tests of the UDF has been put on hold because of the fact that acoustic pressure was so high that cracks has started build up in the FTB's fuselage structure almost instantly. This is why GE inside assessment for this was "no go" for the direct drive fan type. Right now what is worked with Safran this is geared version - from practical standpoint this is just large turboprop with fancy looking fixed-pitch propeller. I think reducing blades number and adding PCM will be next step (just matter of time and xxx mln of USD)- this way GE/Safran will close the loop and will reach conclusion that turboprop is most efficient form of turbine propulsion (kind of discovery isn't it?).

really ? a fixed pitch prop ? didn't they go out in the '30s ?

another day in paradise, or is paradise one day closer ?

yes - simply is spinning much faster than standard propeller but still slower than original UDF- if you have seen pictures they have added additional fixed blades behind propeller for tuning down noise - child of CFD analysis :D

What problem is this aircraft trying to solve?

those blades look variable pitch ?

If the blades spin faster than normal turboprop, are the tips supersonic ??

"What problem is this aircraft trying to solve?" ... I don't know ... maybe a solution looking for a problem ? I suspect it's a marketing solution to a future problem.

another day in paradise, or is paradise one day closer ?

It occurs to me that if you put the engine shown by jaceb in his picture inside a cylinder that you could improve things by reducing radial flow, and maybe control noise as well.

Maybe I should patent that idea before anyone else thinks about it.

I've been wondering what it'd be like if you replaced the hot section with an electric motor. How much thrust from just the LP fan ?

another day in paradise, or is paradise one day closer ?

Quote (rb1957)

I've been wondering what it'd be like if you replaced the hot section with an electric motor.

Doesn't that get us to thread2-486123: A slight design change?

if you dump the nacelle and 1/2 the blades.

another day in paradise, or is paradise one day closer ?

the point is to have bigger fan/propeller/propfan without drag penalty coming out from enormous nacelle, actually for contemporary engines fan is responsible for generating around 80%+ of thrust, and yes - its spinning fast enough to exceed Mach 1 at the tip (dont ask how this vanes will help with this fact - this is sweet secret of the CFD peoples from GE), for the narrow body engine engine you will need (i had this number somewhere at the back of my head) 20MW+ of power - your heat rejection in this case will be 200kW from electric motor and additional 100kW from gearbox if you have any + inefficiencies coming out from power conversion system - but this again will lead us to the discussion on the electric propulsion suitability for the aircrafts - probably all of us have their own opinions related to this one.

about question what problem we are trying to solve - 2050 is declared date for carbon neutral economy - 2035 is the deadline for 50% reduction in CO2 emission - at least in EU. Considering all options we have on the table - in my opinion - only workable one is significant increase in fuel economy of aircrafts which is possible only with turboprop type propulsion. All other options are in best case niche filling (read BS). Of course alternatively we may stop flying and start walking and chatting with friends from other side of Atlantic via internet.