Not being very technically minded, I had never really understood why this feature had been chosen on a very few aircraft, but I finally recently got an explanation which made it clear.

I was touring an ex-RAF Avro Shackleton and an ex-crew member was on hand to answer questions, so I asked him why the designers had chosen contra-rotating propellors.

He explained that it was because of the very high power of the aircraft's (RR Griffon) engines and that because of this and to avoid having immense and unmanageable single propellors, the designers had opted for contra-rotating propellors.

In other words, this was the only practicable way of transforming the engines' power into effective motive force, so presumably this aim overrode the undoubted complications of the choice of such a design.

Anyone else got any comments on this? It must be something of a last resort design choice I would think, because I can only think of a handful of aircraft where this design solution was chosen: the Shackleton, the Antonov 22, the Fairey Gannet, the Westland Wyvern, the Tupolev 95/114. Can anyone think of any others?

I once stood under and a short distance to the side of an An22 landing and the noise was awesome.

Michael, Contra Rotating Props were also fitted to the last model RN Supermarine Seafire.

With the power of the RR Griffon and given the explanantion told to you, it makes sense as there was not a lot of room on those old WW2 era FAA Carriers for very large propellors. Hence also, the choice of a 5 bladed prop for the Hawker Sea Fury v the larger 4 bladed one on the Hawker Fury of the same vintage.

There was an American entry to the counter rotating propeller program. It was an eight engine Convair flying boat built for the US Navy in the 1950's. I think they were powered with Allison turbojet engines linked up to reduction gears which inturn turned over the eight propellers in front of four nacelles. The airplane was a very good looking craft but the counter rotating system, from what I understand was very undependable. One of the airplanes crashed off of San Diego's Point Loma.
However this particular incident was blamed on
control surface linkage and not the propellers or engines. All crew bailed out safely. There was an incident however where at least one of the engines refused to throttle down following a water landing up in the Alameda area I believe, causing the aircraft to crash headlong into a breakwater which ripped out the keel section of the hull.

Doug

The Northrup XB-35 flying wing bomber also used contra rotating props in a pusher configuration. I remember reading that they had a lot of transmission problems with the props.

Willy

Yes,

It did in one of the test configs.

Didn't the Bristol Brabazon have Contra rotating Props as well?

Yes it did David and I've just thought of another one: the Saunders Roe Princess-ten engines!

Of course. I should have looked at the video either you or Doug sent me (can't quite remember who - my apologies.)

The Convair seaplane was called the "Tradewinds". It had the unique capability of taxiing right up to a beach, opening the front like a C-5, and discharging vehicles and troops right onto the shore. The props could be put into reverse pitch and the seaplane backed right off the beach again.

Like the Saunders-Roe Princess flying boats, the concept was overshadowed by the glut of land-based aircraft available after the war, and with the multitude of airfields available, the days of the flying boat were over.

The three Princesses made were flown for a while, then mothballed and eventually scrapped.

Very interesting aircraft Walt-I'd never even heard of it.

For more details, go to www.aviation-history.com/convair/tradewind.html

A very sleek and powerful aircraft, apparently let down by unreliable engines.

I remember the airplane.

Revell made plastic kit of it. From time to time 1 comes up on E-Bay.

Douglas also built a variant of the AD Skyraider called the A2D Skyshark. It used the Allison T40 turboprop with contra-rotating props, same as in the Convair Tradewind. It suffered from the same problems, and the program was terminated. The metallurgy used in the transfer case was not able to withstand the torque output of the engine. There were about 10-15 aircraft built.

Only one airframe survived the scrapping that took place after the program termination. It was given to the Planes of Fame Museum. I saw this aircraft at Chino, California in 1992, parked outdoors between a couple of the hangars. It was in a bare-metal finish, with no markings. I don't know what eventually became of it after that. If anyone knows, I'd like to hear it.

This message has been edited. Last edited by: Walt McKinney,

Some time ago I read about an effort to restore the Skyshark further. Someone had acquired a complete powerplant, twin coupled turboprop engines. Flight seemed unlikely since the gearboxes were not reliable even when new. Only the Russians seemed to have conquered the reliability problems on contraprop gearboxes (TU 95). UK and US never seemd to do as well. Contraprops are supposed to be more efficient and also solve the torque related control problems that come from coupling a lot of power to single props. Volvo uses a contraprop setup on many of their marine I/O engines.

[QUOTE]Originally posted by Walt McKinney:
<<The Convair seaplane was called the "Tradewinds". It had the unique capability of taxiing right up to a beach, opening the front like a C-5, and discharging vehicles and troops right onto the shore. The props could be put into reverse pitch and the seaplane backed right off the beach again.>>

That concept was so flawed. How many beaches have characteristics suitable for this kind of operation? Very few. Note in the stock photos of the Tradewinds beach landings there is NO surf and NO wind, probably shot inside a well protected harbor. It was tough enough to get an LCVP or LST (often deploying stern anchors to keep from going broadside to the waves)into a good beach landing let alone a giant seaplane which wants to weathercock into the wind and which would be permanently beached if there were any appreciable surf. The idea, though flawed, did result in some nice publicity shots.

The Tu-95 eventually developed into the Tu-114 propliner, the only one ever with c/r props:
http://www.airliners.net/open.file/523182/M/

Unmistakeable sound when flying, although it must be 40+ years since I last heard it

Wasn't this the aircraft that flew Kruschev to the USA for his 1959 visit? I think I recognise the registration from shots of the TU114 used, that I've seen in the past, though I can't find any now.

Also, another thing about contra-rotating propellors: doesn't the backwash from the forward propellor mess up the airflow for the rear propellor?

I agree, only the Russians seem to have fully mastered this feature for transport use.

Here's a link to a site with info on the A2D Skyshark and photos of a model of it, which are in greater detail than the actual photos of the time.

http://modelingmadness.com/reviews/korean/cleavera2d.htm

Planes of Fame has told me that the airframe still exists, and is owned by one of the former denizens of Chino, CA, who is now living in Idaho. Plans for restoration are uncertain.

quote:

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Originally posted by Michael Blank:
Wasn't this the aircraft that flew Kruschev to the USA for his 1959 visit? I think I recognise the registration from shots of the TU114 used, that I've seen in the past, though I can't find any now.

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Right you are - I had the pleasure of actually touring that TU-114 when it arrived at Idlewild in 1959. My Dad took the family to see it, and as a plane-nutty child of six, I had a blast! I remember several things after all these years. The US ground crew had to prepare a makeshift set of stairs to reach the cabin doors, since the fuselage was so high off the ground. The cabin was trimmed in maroon brocade and etched glass, with brass railings on the hatracks that looked like something out of a Victorian mansion. The lavs contained real PORCELAIN fixtures!
And the best thing was - I almost started an international incident! When we were outside the aircraft, I ran over to one of the inboard sets of props. These were so big that the tips nearly reached the ground. Being the precocious child I was, I immediately reached up and tried to turn the blades, and (being a turboprop) they of course began to turn.
Before my Dad could stop me, this big Russian guard in a bearskin cap came running up, yelling NYET!! NYET!! My Dad grabbed me and hauled me away posthaste.
This from the same kid who pulled the inside weatherstrip off a DC-6 passenger window when I was three. Dad had to go up and tell the crew, and we had to change planes at the next stop!

Good to be part of this discussion group.

HANDS OFF PAUL OR I'LL SLAP THEM OFF! You know better than to touch anything Soviet!!:-)


Doug

Response to Paul Kile: great stuff! I'd heard the interior of these aircraft was extraordinary, because one flew into London Heathrow in the 1960s and took a party of British newspapermen to Moscow and back and some photos of its interior are on the net somewhere.

Hope I can make it to Moscow and Monino some day, because that's the only way I'm going to get to see a couple of these monsters now.

I think it's also worth mentioning that the TU114 could equal the speed of modern jetliners-amazing, but then it was the only turboprop aircraft with swept back wings, as far as I know.

This message has been edited. Last edited by: Michael Blank,

Hi,

In case anyone here has Flight Simulator 2004, a model of the TU-114 complete with interior has been released:

http://library.avsim.net/search.php?CatID=root&SearchTerm=tu-114&Sort=Downloads&ScanMode=0&Go=Change+View

Hope this helps,