×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Engine-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Engine-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

what's old is new again ...

what's old is new again ...

what's old is new again ...

(OP)
from flight ...
Embraer tweaks turboprop concept to have aft-mounted engines ...



didn't Boeing try this in the 90s ?

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

RE: what's old is new again ...

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

RE: what's old is new again ...

(OP)
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 ?

RE: what's old is new again ...

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

RE: what's old is new again ...

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.

RE: what's old is new again ...

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.

RE: what's old is new again ...

Bit of a thin looking wing in that top photo.

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

RE: what's old is new again ...

(OP)
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 ?

RE: what's old is new again ...

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.

RE: what's old is new again ...

(OP)
why not on the wing, as the great designer intended ?

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

RE: what's old is new again ...

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

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: what's old is new again ...

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

RE: what's old is new again ...

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?).

RE: what's old is new again ...

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

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

RE: what's old is new again ...

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

RE: what's old is new again ...

What problem is this aircraft trying to solve?

RE: what's old is new again ...

(OP)
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 ?

RE: what's old is new again ...

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.

RE: what's old is new again ...

(OP)
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 ?

RE: what's old is new again ...

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?

RE: what's old is new again ...

(OP)
if you dump the nacelle and 1/2 the blades.

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

RE: what's old is new again ...

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.

RE: what's old is new again ...

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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Engine-Tips Forums free from inappropriate posts.
The Engine-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Engine-Tips forums is a member-only feature.

Click Here to join Engine-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Engine-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Engine-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close