LHX Program

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.
 
From, United_States_Army_Aviation_Digest
 

Attachments

  • 10.png
    10.png
    5.3 MB · Views: 182
  • 22.png
    22.png
    600.5 KB · Views: 66
  • 21.png
    21.png
    477.1 KB · Views: 87
  • 20.png
    20.png
    390.1 KB · Views: 86
  • 19.png
    19.png
    1.2 MB · Views: 83
  • 18.png
    18.png
    548.7 KB · Views: 59
  • 17.png
    17.png
    431.2 KB · Views: 45
  • 16.png
    16.png
    452 KB · Views: 45
  • 15.png
    15.png
    749.1 KB · Views: 45
  • 14.png
    14.png
    1.1 MB · Views: 47
  • 13.png
    13.png
    815.5 KB · Views: 48
  • 12.png
    12.png
    503.8 KB · Views: 52
  • 11.png
    11.png
    1 MB · Views: 58
  • 23.png
    23.png
    535.8 KB · Views: 53
  • 24.png
    24.png
    1.2 MB · Views: 53
  • 25.png
    25.png
    608.8 KB · Views: 116
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?
 
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?
 
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.
 
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.
 
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.
 
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
 
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
 
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.
 
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.
 
From Army Aviation 1981/5
 

Attachments

  • 20.png
    20.png
    474 KB · Views: 56
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.
 
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:

 
That was exactly what I thought when I first saw that photo myself yasotay, certainly looked weird for the time.
 
From Army Aviation 1984/6.
 

Attachments

  • 40.png
    40.png
    1.3 MB · Views: 8
  • 41.png
    41.png
    1.2 MB · Views: 9
  • 42.png
    42.png
    1.2 MB · Views: 9
  • 43.png
    43.png
    1.1 MB · Views: 8
  • 44.png
    44.png
    1.9 MB · Views: 7
  • 45.png
    45.png
    1.3 MB · Views: 8
  • 46.png
    46.png
    1.1 MB · Views: 7
  • 47.png
    47.png
    1.2 MB · Views: 7
  • 48.png
    48.png
    1.2 MB · Views: 7
  • 49.png
    49.png
    1.4 MB · Views: 7
  • 50.png
    50.png
    1.3 MB · Views: 6
  • 51.png
    51.png
    2 MB · Views: 10
Also from Army Aviation 1985/6.
 

Attachments

  • 52.png
    52.png
    2.5 MB · Views: 11
  • 53.png
    53.png
    838.1 KB · Views: 11
  • 54.png
    54.png
    1.2 MB · Views: 9
  • 55.png
    55.png
    1.2 MB · Views: 10
  • 56.png
    56.png
    1.4 MB · Views: 10
  • 57.png
    57.png
    1.5 MB · Views: 11

Similar threads

Back
Top Bottom