Rombac111
Topic Author
Posts: 51
Joined: Tue Jul 20, 1999 11:13 pm

An-22

Mon Jan 08, 2001 9:54 pm

Hi all !
Have you noticed that we have pointed russian aircrafts !
They use to make "different" planes... like mutants  

Have you seen the An-22 ?



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Click here for full size photo!

Photo © Dietmar Schreiber




It has doubled-blades ! Why is that ?... any comment ?... does it produces more thrust or something like that ? does any other plane is alike ? it is interesting... despite i like jet airlines, non bladed ones

See you !


Martìn
aka Rombac 1-11

 
Guest

RE: An-22

Mon Jan 08, 2001 10:50 pm

hi,
it's used with powerful engines, i think it somehow makes the the a/c easier to control...the an-70, a new transport aircraft has got this system, too. it was used with the tu-114 and its versions as well, and the turboprop engines at this plane had 14000 shp (shaft horsepower) each.

i think that a turning propeller makes the aircraft to which it belongs turn zhe other way, that's why helicopters need a tail rotor (or another main rotor, turning the other way), so that they can be controlled. if you've got a very powerful engine you have to compensate the torque.

hope this helps  
jsb
 
prebennorholm
Posts: 6430
Joined: Tue Mar 21, 2000 6:25 am

RE: An-22

Tue Jan 09, 2001 1:42 am

Dear Rombac111,
Contra rotating propellers is nothing really new. The oldest plane, which comes into my mind, is one version of the experimental Heinkel He-177 bomber of WWII, the "Ural Bomber", which never entered service.
The widest use, I think, is the Tupolev Tu-20 Bear bomber and its cousins Tu-95 and Tu-114. Also French (and British?) Navy had a carrier based single engine fighter plane some 30-40 years back - don't remember its name right now. And the Avro Schackleton, didn't it have contra rotating propellers too? - maybe I remember wrong.
It is really surprising that it hasn't been more widely used, especially on powerful single engine aircrafts. It would eliminate the asymmetric gyro effects which has killed a lot of good pilots over the years.
My guess is that it was too expensive, too heavy, and probably too maintenance intensive for use where they could really have made a difference, on WWII and later single engine propeller fighter planes.
On the four engined Tu-20 Bear and AN-22 I think that the reason for contra rotating propellers was somewhat different. To get rid of those 15,000 HP a single propeller would be much larger in diameter and call for extremely long landing gear legs, and besides that it would be difficult to keep the blade tips at subsonic speed. They probably didn't mind the extreme noise of supersonic propeller tips, but the efficiency of a propeller going supersonic is much inferiour to one going subsonic.
Only one plane has - to my knowledge - been designed to fly with a supersonic propeller, The Republic YF-84H - a turboprop version of the famous F-84F Thunderstreak fighter. That project was cancelled. I have read that one major reason for the cancelation was that the noise was absolutely unbearable, even when mixing with other fighter planes with afterburner.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs
 
Guest

RE: Prebennorholm

Tue Jan 09, 2001 10:28 pm

hi,
you are right, the shackleton had contra-rotating propellers, and the single-engined carrier based plane was a later version of the supermarine seafire (carrier.based version of the famous spitfire) with some 2300 hp.
the propellers of the tu-114 already had a diameter of 5.6 meters, i would gladly hear such a plane take off  
jsb
 
prebennorholm
Posts: 6430
Joined: Tue Mar 21, 2000 6:25 am

RE: Jsbothe

Wed Jan 10, 2001 2:54 am

Jsbothe wrote:
-------------------------------
....and the single-engined carrier based plane was a later version of the supermarine seafire (carrier.based version of the famous spitfire) with some 2300 hp.
-------------------------------

Okay, then there was two of them. The Seafire was not the one which I was thinking of. The one I was thinking of has a very thick fuselage and a huge, smokey turboprop engine. And I think it was French. It was used in the Mediterranian during the Suez Conflict in 1956 or 1957, and probably not much later.
I hate having forgotten a name of a plane.  
Best regards, preben Norholm
Always keep your number of landings equal to your number of take-offs
 
tr1492
Posts: 108
Joined: Tue Feb 08, 2000 2:15 am

RE: An-22

Thu Jan 11, 2001 12:36 pm

Preben - is this the plane you're thinking of??


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Click here for full size photo!

Photo © Peter Vercruijsse



As soon as I read your post, I remembered the plane but forgot it's name also!! Took a little time to jog the memory! This is the only pic of an Alize in the database here - from this pic I can't tell if this plane has counterrotating props, but I know I've seen other photo's of the Alize which clearly show the cr props.

Regards,
Tom
 
prebennorholm
Posts: 6430
Joined: Tue Mar 21, 2000 6:25 am

RE: Tr1492

Fri Jan 12, 2001 7:32 am

Yeah, Tom. Exactly!
Thanks for refreshing my rusty memory.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs

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