Changing the RR Merlin engine to the Allison T56 turbo prop

[McColm]

The first Allison T56 turbo prop engine was fitted in the nose of a B-17 in 1954, which got me thinking what if the Air Ministry at the time had decided to replace all the Merlin powered aircraft in service at the time. With over 45 different aircraft types to choose from in service with the RAF and airliners , this must be a Whiffers paradise.
Flightpath supply the long nosed T56 in resin 1/72 scale.
Most Bristol Hercules powered aircraft could have the RR Griffon as a replacement and I know that the Lockheed Constellation can be converted with a small amount of filler and the changing position of exhaust pipes. (on going project of mine).

[Jay-Jay]

  yumi yumi !!! that sounds attractive !!
I am also working on the same idea to re-engine a RR engined british fighter but with a Whif british turboprop..
Again I will pray Model Kit builder God to have more time and resources to achieve this project.....
Whif World is a REAL paradise I love to travel across  
RGDS
JJ

[perttime]

The T56 seems to be about the same weight as a Griffon, but it looks pretty long with the gearbox unit (?) mounted far forward of the rest of the engine. Way more power....

The length may make it awkward to fit on small singleseat airplanes but it should be perfect for anything bigger.

[wuzak]

http://en.wikipedia.org/wiki/Allison_T56

The Allison T56 is 1940lbs, comapred to a Griffon 65 at 2090lbs, Griffon 130 at 2165lb (contra-rotating props) and Griffon 37 at 1930lb. The Griffon weights don't take into account the weight of the cooling system.

The T56 is 146" long, compared to the Griffon 65's 81" , 130's 82.5" and the 37's 71.1".

At 27"in diameter it is narrower than the Griffon (29.5" for 2 stage, 30.3"for single stage).

The T56 is as much as twice as powerful, though. So it could prove to be a bit of a handful in a single seater!

If you're replacing Merlins, you could look at the Rolls-Royce Dart.

Wider than the Griffon and Merlin (37.9" vs ~30"), though not as tall (46" and 40" respectively). 1630shp and 1850ehp (includes contubution from thrust. Best bit is it weighs just over 1200lbs!

It is longer than the Merlin or Griffon, at 97.6".

And it first ran in 1946.


Or how about a coupled GE T58 installation?
http://en.wikipedia.org/wiki/General_Electric_T58

1250hp each, 16" in diameter, 55" long and 400lb (each) including the reduction gear. Wiki says first run in 1955.

Sort of like an Armstrong Siddeley Double Mamba - 2960ehp, 102.25" long, 52.8" wide (I assume ~30" high based on the Mamba), 2170lb weight.

[Jay-Jay]

Thanks for these very useful data.  
I do agree that Dart is more suitable when replacing Merlin (refering to the Cavalier mustang).
PW PT6 engine is also a good engine for old airframe. But that's real life...
Suggestion: Why not take the question by the other side of the equation: take a T56 engine and try to bring around bitz and parts of old airframes....
Lot of diplomacy discussions with your wallet and hours of Kitbash but it may pay off at the end (is my english correct?)  
RGDS
JJ

[McColm]

The only 1/72 kits I know to source the engines from are:
Double mamba - Gannet
Dart      -          Fokker F27
Tyne     -         C-160 and Breguet Br.1150 Atlantic
Napier Eland      Rotordyne

Heritage Aviation Models Limited do a range of 1/72 and 1/48 resin engines including; the cavalier mustang, RR Dart, Alllison T-56 and the Pratt & Whitney PT6A.
I'm building another Lockheed Constellation with the Pratt & Whitney PT6A turbo prop as used by the SAAF on their Dakotas.

[PR19_Kit]

Using the Gannet fuselage as a source for a Double-Mamba installation isn't too good an idea as it has a VAST amount of extra 'stuff' around it, close cowled it is NOT! Pehaps the only useful bits would be the intake and the prop assembly, all the rest could be any shape you like, and luckily the Mamba was quite a small engine, even in Double form.

[wuzak]

Was just looking at the Napier Eland - 3500hp, 1735lb, diameter 36", length 120".

http://en.wikipedia.org/wiki/Napier_Eland

Used in:
Airspeed Ambassador
Canadair CC-109 Cosmopolitan
Canadair CL-66
Convair CV-540
Fairey Rotodyne

And checked out the link to the Lycoming T55.

http://en.wikipedia.org/wiki/Lycoming_T55

4800hp, 830lb, 24.3" diameter, 47" long!

Bell 309
Boeing CH-47 Chinook
Boeing Chinook (UK variants)
Boeing Model 360
Curtiss-Wright X-19
North American YAT-28E Trojan
Piper PA-48 Enforcer

[kitnut617]

Used in:
Canadair CC-109 Cosmopolitan
Canadair CL-66

The Canadair CL-66 is a CC-109 Cosmopolitan

[The Wooksta!]

You can't simply swap a Hercules (of which there were literally tons of spares for) for Griffons without affecting the aerodynamics - you're changing the thrust line ie where the power is applied - or drastically altering the engineering structure of an already completed (and largely obsolescent) design.  The Hercules is a radial with the crankshaft in the centre, the Griffon an upright V12 with the crankshaft near the top.

"Ah, but what about the Beaufighter?"  True but look at the side views of how the engine is mounted and where the prop/thrustline goes.  In both, it's right through the wing.

[kitbasher]

You can't simply swap a Hercules (of which there were literally tons of spares for) for Griffons without affecting the aerodynamics - you're changing the thrust line ie where the power is applied - or drastically altering the engineering structure of an already completed (and largely obsolescent) design.  The Hercules is a radial with the crankshaft in the centre, the Griffon an upright V12 with the crankshaft near the top.

Looks good though - http://www.whatifmodelers.com/index.php?topic=31451.msg483259#msg483259

[wuzak]

You can't simply swap a Hercules (of which there were literally tons of spares for) for Griffons without affecting the aerodynamics - you're changing the thrust line ie where the power is applied - or drastically altering the engineering structure of an already completed (and largely obsolescent) design.  The Hercules is a radial with the crankshaft in the centre, the Griffon an upright V12 with the crankshaft near the top.

"Ah, but what about the Beaufighter?"  True but look at the side views of how the engine is mounted and where the prop/thrustline goes.  In both, it's right through the wing.

The Griffon's crankshaft is at the bottom of the engine, but its prop shaft is offset to the middle of the engine:

http://farm7.staticflickr.com/6122/5993278574_cc0403d49c_o.jpg

And the Griffon Beaufighter:

[Jay-Jay]

Hello,

About RR Dart engine, while Goggle-ing; I found out some very useful pictures of Cavalier mustang with drawings from Airfix Magazine.
I have to check my history log but think it was on britmodeller. The scale is 1/24 but it can be easily turned into 1/72 & 1/48 scales (Thanks the office printer !  )
Until I get back the link, any of interested modelers can PM.

JJ

[Jay-Jay]

Hello,

About RR Dart engine, while Goggle-ing; I found out some very useful pictures of Cavalier mustang with drawings from Airfix Magazine.
I have to check my history log but think it was on britmodeller. The scale is 1/24 but it can be easily turned into 1/72 & 1/48 scales (Thanks the office printer !  )
Until I get back the link, any of interested modelers can PM.

JJ

Check at Airfix tribute forum or type in Google for "Cavalier Mustang+Airfix Magazine" and look for images

JJ

[McColm]

Another idea  l have is to change the engines on the Airfix Short Sunderland , four Griffons or the PT6A from the Heritage Aviation Model range.  I have used these on two Lockheed C-69 Constellation builds . This would look great on a Sandringham conversion or a armed Sandringham.As this topic keeps cropping up .