Reluctant Poster
Tech Sergeant
- 1,638
- Dec 6, 2006
Rolls Royce was developing a 3 speed drive for the Merlin supercharger. I believe a 3 speed Griffon actually flew in a Spiteful. Do you have any history on the Merlin 3 speed?
Engine choices for P-51 mustang ?
- Thread starter VA5124
- Start date
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Shortround6
Major General
Sure, you just needed a Tardis to do it in WW II.
Or did you mean a gas turbine without a Prop?
The wing was similar in shape to the Mustang but it was not a Mustang wing, the landing gear was well back in the wing and the wing root extensions did not house the landing gear.
Admiral Beez
Major
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drgondog
Major
offhand i'd say from front line of French/German border to Nantes?
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
As was Heinkel and Junkers.
Neither left the design stage before war's end, but the Soviets did pursue the Jumo012/022 design, which eventually became the Kuznetsov NK-12, postwar.
Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
I do not.
I am hoping they might reopen their archives next year, which were already very tortuous
to get into...sort of like reverse Colditz.
glennasher
Senior Airman
I always liked the Piper Enforcer, it's a neat design. Dunno how useful it might have been, but it looks cool.
Shortround6
Major General
The Americans were also working on a turbo prop. It arrived a bit late.
However a turboprop is actually more difficult than a turbojet.
You have to design and build the gearbox section and you have design a turbine section that can not only power the compressor but get enough power out of the exhaust (or soon to be exhaust) to power the actual propeller. Many early turbo props added extra turbine stages to power the prop. The GE engine used a single stage turbine of large diameter (and used air cooled nozzle guide vanes.
wuzak
Captain
Metropolitan Vickers were working on a turboprop before WW2. The program changed to a turbojet after Whittle demonstrated his jet.
Shortround6
Major General
It wound up that most countries, despite have drawings/prototypes for turboprops/shaft turbines all through their development histories, took longer to get turbo props into service.
If you could actually design and build a successful turboprop you could yank the gear box off and take out one or two turbine discs and have a successful turbojet.
The Turboprop was NOT a short cut to the turbojet.
The Turboprop was a more complicated project than a turbojet.
There were a lot designs/projects, getting them to work was the problem.
Brown-Boveri was testing a gas turbine railroad locomotive in 1941-42, they were getting 8000hp out of the turbine but it took 6000hp to run the compressor.
Getting the thing to even fit in an airplane (even a 6 engine flying boat) wasn't going to happen.
Theory and ideas they had in the late 30s and early 40s. Getting them to actually work and last a few hours was the hard part.
wuzak
Captain
I didn't say it was easier, I just said that Metropolitan Vickers started out designing a turboprop.
Probably because on of the project leads, AA Griffith, did not believe in jet propulsion at the time. Griffith had written a paper about the design of gas turbine engines in 1926, part of which included a hypothetical design for a turboprop.
Gas turbines existed before then, they just weren't very efficient.
The turbine Metrovicks was working on would lead to the jet F.2 that flew in the Meteor in 1943, only a few months after the Whittle engine prototype.
Apparently the way Metrovicks worked was frustrating for many. As manufacturers of steam turbines they took longer to produce items and weren't overly concerned with weight.
Howard Gibson
Senior Airman
Why?
The speed of a propeller driven fighter plane is limited by the propeller, something a bit over 500mph. The world piston speed record now is around 528mph, not much faster than the P-47J during WWII. This was well known back in the forties. Quantum speed improvements require turbojets.
wuzak
Captain
The Tu 95 has a rated top speed of 575mph, but may have exceeded 600mph in level flight.
The official record for the fastest propeller driven aircraft is held by the Piaggio P.180 Avanti at 576mph.
Thumpalumpacus
Major
I don't know much about airplane engines, but given that oil is lubricating the passage of the piston through the cylinder, if the cylinder itself is perforated you're damned sure losing oil with every piston-stroke. Cylinder deformation may or may not result in oil loss, but it's perhaps a bigger problem, because that detonation has to go somewhere.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
One of the differences between a V-1710 or V-1650 and a radial like the R-2800, are the main bearings.
In the inline engines, the crank is "floating" between the bearings by means of hydraulic pressure. Once damage has occurred to the engine, resulting in loss of oil pressure, the crankshaft starts grinding on the bearings and engine seizure is soon to follow.
In the radial, the main bearings were roller bearings that relied on a "wash" to keep them lubricated, so a loss of oil pressure did not result in the same failure as the above-mentioned.
Add to this, that the radial was not dependant on liquid coolant to operate, so damage that resulted in loss of it's oil would not cause immediate failure.
This is not to say that it would run indefinitely in the event of critical damage, but it would far outlast an inline that suffered comparable damage.
In the inline engines, the crank is "floating" between the bearings by means of hydraulic pressure. Once damage has occurred to the engine, resulting in loss of oil pressure, the crankshaft starts grinding on the bearings and engine seizure is soon to follow.
In the radial, the main bearings were roller bearings that relied on a "wash" to keep them lubricated, so a loss of oil pressure did not result in the same failure as the above-mentioned.
Add to this, that the radial was not dependant on liquid coolant to operate, so damage that resulted in loss of it's oil would not cause immediate failure.
This is not to say that it would run indefinitely in the event of critical damage, but it would far outlast an inline that suffered comparable damage.
Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
Agree about turbines, but its not a very good comparison to say that a P-47J is nearly as fast as the current air speed record planes, it certainly
does not fly even vaguely close to that speed at sea level where those records are set, and those planes need about double the power
of a P-47 to do it.
drgondog
Major
Two things Howard. Voodoo had one run at 550+, the 528+ was an average, hampered by a failing engine. Second, Voodo was at about 5000 ft - at a speed about 100mph faster than a P-47D/M at the same altitude.
True that that both the increased pressure drag and tip speed limitations provide an asymptotic limit below M=1, but so does the overall combined parasite and induced and Mach related compressible flow drag on a conventional fuselage/wing combo.
Gloster Trent-Meteor
ww2aircraft.net
