LHX Program

[Scott Kenny]

What if?????
Those paintings got me to wondering how it would fly if you installed the tail rotor in a hole (fenestron) cut in one half of the V tail?

Think of the tilted tail rotor on Sikorsky CH-53 ... which helps adjust pitch trim. Pitch trim is important on cargo helicopters that frequently change balance as they off-load cargo, troops, etc.

IIRC, Fenestrons actually take a bit more horsepower than a conventional tail rotor.

 

[ZacYates]

So it seems the concept art is as misleading as the ATF art.

That's disappointing to hear as I've always been a fan of this version. I would LOVE to see what it actually looked like!!

 

[hesham]

From, United_States_Army_Aviation_Digest

 

[Foo Fighter]

IIRC, Fenestrons actually take a bit more horsepower than a conventional tail rotor.

Is there a correlation of the Fenestron design and the redirected engine exahust method of longitudonal stability?

 

[Scott Kenny]

Is there a correlation of the Fenestron design and the redirected engine exahust method of longitudonal stability?

Fenestron versus NOTAR?

I'm not aware of any comparisons made between those two, but I'd suspect the fenestron needs less power than NOTAR (less fluid losses since there's a short tube). Maybe Yasotay would know?

 

[dan_inbox]

I'd suspect the fenestron needs less power than NOTAR (less fluid losses since there's a short tube).

Less fluid losses but mechanical losses in the 90° shaft angles

 

[Scott Kenny]

Less fluid losses but mechanical losses in the 90° shaft angles

Sure, but we already know that NOTAR takes more power than a conventional tail rotor, and a fenestron has that same 90deg gearbox.

 

[yasotay]

In The RAH-66 Comanche Helicopter: Technical Accomplishment, Program Frustration, by Arthur W. Linden, there is an entire chapter on the tail rotor development. In the trades process they decided on the fenestron over conventional tail rotor, and interestingly enough, they even considered NOTAR, albeit for a very short period. They acknowledged that the fenestron required more power. However given the mission; low level reconnaissance in high threat environments, it was the best compromise between efficiency of power use, stealth, and mission safety.

The book is not inexpensive, $40 US on Amazon, but it is the most complete and authoritative book on the development of RAH-66. The first 3/4 of the book is focused on the engineering aspects of the program, while the last 1/4 is the sad tale of how the government slowly and expensively delayed the program into irrelevance. I do recommend it if you have an interest in this aircraft.

 

[Scott Kenny]

In The RAH-66 Comanche Helicopter: Technical Accomplishment, Program Frustration, by Arthur W. Linden,

Ooooh, thank you for that recommendation!

The place we do see lots of fenestrons or NOTAR is civilian medevac helicopters, and that seems to be from the point of keeping idiots out of the rotors.

 

[yasotay]

Ooooh, thank you for that recommendation!

The place we do see lots of fenestrons or NOTAR is civilian medevac helicopters, and that seems to be from the point of keeping idiots out of the rotors.

... and not learning the hard way that you trapesed your tail rotor through the trees on approach.

 

[hesham]

From Army Aviation magazine1980 .

 

[yasotay]

From Army Aviation magazine1980 .

Likely an Army artist interpretation of one of the MANY variations of a theme from Sikorsky.

 

[BlackBat242]

From, United_States_Army_Aviation_Digest

https://www.secretprojects.co.uk/attachments/22-png.716160/

My immediate reaction was to finish the lyric.
"In pieces on the ground".

As kinda happened, referring to the project.

 

[hesham]

From Army Aviation magazine1980 .

From the same source.

 

[hesham]

Hi,

https://rotorcraft.arc.nasa.gov/Scully_TP-2018-219981_final.pdf

 

[Mark Nankivil]

In The RAH-66 Comanche Helicopter: Technical Accomplishment, Program Frustration, by Arthur W. Linden, there is an entire chapter on the tail rotor development. In the trades process they decided on the fenestron over conventional tail rotor, and interestingly enough, they even considered NOTAR, albeit for a very short period. They acknowledged that the fenestron required more power. However given the mission; low level reconnaissance in high threat environments, it was the best compromise between efficiency of power use, stealth, and mission safety.

The book is not inexpensive, $40 US on Amazon, but it is the most complete and authoritative book on the development of RAH-66. The first 3/4 of the book is focused on the engineering aspects of the program, while the last 1/4 is the sad tale of how the government slowly and expensively delayed the program into irrelevance. I do recommend it if you have an interest in this aircraft.

Bought and read it - excellent read on the technical side, depressing as hell on the political side. And now with the demise of FARA, the more things stay the same. Bet those contractor teams could read these book and say "now we've been there, done that".

Enjoy the Day! Mark

 

[Mark Nankivil]

Bought and read it - excellent read on the technical side, depressing as hell on the political side. And now with the demise of FARA, the more things stay the same. Bet those contractor teams could read these book and say "now we've been there, done that".

Enjoy the Day! Mark

What happended to the 2 Commaches - on display anywhere or were they chopped up?

Mark

 

[Colonial-Marine]

I believe one is on display at the Army Aviation Museum and kept indoors in good condition. I'm not sure what happened to the other one. I might have to try to make a visit there someday.

Maybe if they get the prototype Bell 360 and Raider X they can dedicate a whole room to prototypes that were all intended to succeed the Kiowa.

 

[yasotay]

Comanche # 2, along with the only built version of the sensors is in the Army Aviation Museum. I believe that Comanche #1 is at the NASM, although I cannot confirm this.

 

[hesham]

From Army Aviation 1981/5

 

[yasotay]

While this platform can be loosely associated to the LHX program, it was never a contender for the actual program. It was a technology demonstrator for simplified (read cheap), non-metaled aircraft. Bell and Sikorsky won contracts for each to build two demonstrators. Boeing also competed but did not get a contract. Sadly, since the Army bought the aircraft, they were all used for non-destructive testing and no longer exist.

 

[quellish]

While this platform can be loosely associated to the LHX program, it was never a contender for the actual program. It was a technology demonstrator for simplified (read cheap), non-metaled aircraft. Bell and Sikorsky won contracts for each to build two demonstrators. Boeing also competed but did not get a contract. Sadly, since the Army bought the aircraft, they were all used for non-destructive testing and no longer exist.

Thread on ACAP here:

https://www.secretprojects.co.uk/threads/us-army-advanced-composite-airframe-program-acap.12627/

 

[VTOLicious]

Thread on ACAP here:

https://www.secretprojects.co.uk/threads/us-army-advanced-composite-airframe-program-acap.12627/

Great stuff! Thanks for the link!

 

[Dew]

Hughes/MCDD SCAT from GRC via NARA:

 

[yasotay]

Hughes/MCDD SCAT from GRC via NARA:

View attachment 723106

Exceedingly cool, exceedingly impractical.

 

[FighterJock]

That was exactly what I thought when I first saw that photo myself yasotay, certainly looked weird for the time.

 

[hesham]

From Army Aviation 1984/7-8

 

[hesham]

From Army Aviation 1984/6.

 

[hesham]

Also from Army Aviation 1985/6.

 

[yasotay]

Here we are, ~40 years later and it is still unobtainium.

 

[Colonial-Marine]

Here we are, ~40 years later and it is still unobtainium.

But seemingly not due to an inability to build such a thing based on three different models of prototypes that flew or almost flew before their program was cancelled.

I think the one-man crew idea from the early LHX days would now represent a dead-end. You could probably have it work reasonably well in basic regards but not in everything. The second crewman might now be controlling UAVs or just reviewing all of the sensor data coming in from those or other platforms.

 

[hesham]

We still love it.

 

[hesham]

Good morning all.

 

[hesham]

From Army Aviation 1987/1.

 

[hesham]

And from Army Aviation 1987/6

 

[aim9xray]

Recently on eBay. I'm grading this as pre-LHX as the AAH/S-70 mashup (the S-71) looks significantly different.

 

[robunos]

Is it me, or have the model makers used the rotor from a commercial apache kit ?

cheers,
Robin.

 

[Orionblamblam]

Looks like the tail of a Blackhawk...

 

[aim9xray]

Is it me, or have the model makers used the rotor from a commercial apache kit ?

cheers,
Robin.

No. Is likely from same-scale UH-60 Sikorsky factory desk model.

 

[aim9xray]

Looks like the tail of a Blackhawk...

Quite so.