Packard/merlin engines

[Ballistics in Scotland]

37mm cannon on the P39 didn't run through the drive shaft. It's barrel ran through the upper bearing in a gear box that dropped down to receive the drive shaft. Which ran right under the pilots seat. Plane also had 50 caliber synchronized guns above the cannon in the nose plus wing mounted .30 calibers. 50's, 30's and 37mm cannon. Awesome firepower the Russians loved for taking down German bombers. To this day Russia flies a 37mm gun on it's newest fighters.

Allison engines ran much better than the Rolls Royce engines. Merlin's were simply larger displacement and were developed further. We and the Canadians already had RR Merlin's in production before the US entered WWII.

http://commons.wikimedia.org/wiki/Fi...s_at_night.jpg

Indeed it does, and by far the best way of doing it. You do not want to have a propeller-synchronization failure with one of those things. It is fascinating how many innovations mentioned here originated, possibly in less practical form, in WW1 or even earlier. Gottlieb Daimler, for example, patented forced induction long before anybody knew if the internal combustion engine was going to catch on, and the French had turbocharged aircraft in WW1.

George Guynemer and René Fonck both flew Spads with a short, low-velocity 37mm. cannon fitted in just the same way as the Airacobra's. I have heard unconfirmed reports that Guynemer originated it, but Fonck is reputed to have shot down a considerable of aircraft with it I believe it was the gun used as an infantry weapon, and sometimes a very effective one, although the mortar was surely better, and especially so in the trenches.

I know the Spad's version was hand-loaded, and it was probably the version which someone must surely have called quarter-automatic, for it automatically ejected the fired case, and was then loaded by hand. It was probably as fast firing as the weight-carrying capacity of a WW1 fighter made advisable anyway, but it would be nice to have nothing else to do at the time. I have a vague memory that I have seen a photo of one in the front gunner's cockpit of a very early pusher biplane, which seems like the most practical way to use the thing, but nobody gets famous in one of those.


The Airacobra's drive shaft is variously reported as running under the floor and between the pilot's legs. I don't know which, but the former, or at most between his feet, sounds the more plausible. The rear-engine MB1 was a light civilian aircraft, in which the shaft ran quite high up, between the side-by-side pilot and passenger. Even lightplanes crash sometimes, and two's company in that situation.

[Echo]

A couple of corrections - first, Rare Bear has a Wright 3350, not a Pratt 4360. I talked to the mechanic, who said that the owner had asked about converting to the turbo-compound 3350 that uses the exhaust gasses to 3 power turbines, that return that power to the crankshaft via a gear reduction and fluid coupling. Each turbine returns 500 hp to the crankshaft at full throttle, at no cost other than weight for the additional machinery. The mechanic demurred, saying "We've got 550 cubic inches on the 2800's and that TC engine is 10" longer, meaning we would have to add a couple hundred pounds to the tail area for balance". The TC 3350 turned out as much power as the 4360, and weighed less. Fairchild C-119's had both, 3350' & 4360's. I imagine performance was about the same, but I would like to hear from someone who had experience in both airplanes.
Seecondly, the -51 feature that allowed them to accompany bombers deep into German-held territory was not the Merlin, but the low-drag laminar-flow wing design. That reduced the drag to the extent that they got better mileage, and range, than the Spitfires and Thunderbolts.

[Ballistics in Scotland]

I'm not familiar with the machinery. You mean direct back to the crankshaft, rather than by driving turbocharged induction? That is a step in the direction of the turboprop. I doubt if either is completely at no cost, though, as it would impose backpressure on the exhaust. But that is surely less, and a lot harder to predict the effect, than the power takeoff to get the same benefit from a mechanical supercharger.

[fecmech]

This explains it.
http://aviation-history.com/engines/r3350.htm

The PRT was an exhaust turbine drive mechanical device that was coupled directly to the engine crankshaft. Three PRTs were inserted into the exhaust piping of each group of six cylinders and were geared to the engine crankshaft by fluid couplings. PRTs recovered about 20 percent of the exhaust energy equaling about 550 horsepower at take-off power and 240 horsepower at cruise settings over a similar non-turbo-compounded R-3350. Operation of the PRTs is fully automatic the increased power was achieved with a weight penalty of about 500 pounds.

[Artful]

[Artful]

[MtGun44]

There is a cutaway turbo-compound Wright at the museum here for the Save-A-Connie. That
was the ultimate development of the piston engine. They had three turbines arranged at
120 degrees around the circle, angled inward and their shafts drove fluid couplings to allow
speed mismatches as they needed and vibration decoupling and into a gearbox delivering the
horsepower directly to the crankshaft, rather than driving a compressor like a turbocharger does.
The engines had a normal mechanical supercharger stage, like essentially all large round engines did.

The combustion and primary expansion of the hot gasses was in the pistons, but the secondary
expansion was in the turbines, so half a step towards a turbine engine. The complexity was huge
though and they were expensive to run. VERY fuel efficient, though, which was quite important
on long range over-water routes prior to jets.

Extremely interesting engines.

If you want to see another extremely interesting engine design - there Bristol Centaurus which
was used in the Sea Fury. This was a sleeve-valved engine. The intake and exhaust gas
flow was through ports in the side of the cylinder (near the top) and the sleeve that the
piston rings ran on moved up and down and rotated a bit inside the outer sleeve to move
the holes in the sleeve to line up with the inlet and exhaust ports in the cylinder at the correct
time. Very powerful, smooth, quiet and durable. I have some pix from the museum at
Duxford where they have some partially disassembled for display.

http://aviationshoppe.com/bristol-ce...ine-p-219.html

[Silfield]

http://www.channel4.com/programmes/g...mand/59514-002
Guy Martin is a bit of an eccentric who has made a living as a top motorbike racer (got to be slightly mad to race on twisting streets at 200+ mph!)
He has always wanted a Merlin so has rebuilt one that now sits in his living room as well as helping to restore a Spitfire that was recovered from a beach in France.

[Bad Water Bill]

It says I need my parents PERMISSION to view the video.

At 70++++++ why and how can I get permission from folks that have been buried for many years.

[Artful]

[Silfield]

Thanks Artful,
The link worked straight away from my pc at work when I posted it! Maybe it won't play on your side of the pond because it's a ploy by our guberment to stop any leaks of sensitive military technology .

[Artful]

Maybe your guberment thinks we are all infantile petulant children over here like our president.

[Ballistics in Scotland]

To export a .310 Cadet Martini rifle from Australia once, I had to complete a declaration that it wasn't necessary for the defence of Australia, or bought to be used for attacking anyplace else. Well, neither I have.

[Red River Rick]

If quantity is better...............how about 4 merlin engines!

https://www.youtube.com/watch?v=z4Gh2DfPkP4

RRR

[Bigslug]

One of our local museums has a flying P-38 that - as I recall - runs on two of the V-10 versions of the Allison. Don't know how much is due to the engine design, how much to the fact that there are two of them, or how the noise vibrates through the airframe, but it is a VERY distinctive and cool sounding beast!

My grandfather flew B-26's during the war. SOMEWHERE in the family's stash of his things is an aerial gunnery training manual that I flipped through briefly maybe 15 years ago. Any brain-bending you've ever done over exterior ballistics on your loading bench or leading on the sporting clays field is NOTHING compared with what a waist gunner had to deal with shooting SIDEWAYS out of a bomber moving 250mph at a fighter that might be going 400mph in any possible other direction. Yeah, tracers helped some, but damn!

[MtGun44]

No such thing as "the V-10 version of the Allison". The P-38 runs Allisons with a huge,
complex turbocharger system integrated into each boom. Front inlets are for the
intercoolers, the rear ones on the sides are the radiators for cooling the engines.

The only thing really odd about them is that they run in opposite directions, so one is
a "normal" Allison and the other is a "backwards" Allison. This is to make the airplane
easier to handle on takeoff, much less P-factor (sideways pull from the props) the P-factors
cancel each other out.

[GabbyM]

About thirty years ago there were only three P-38's left in the world that still flew. They have more up now but I don't know the number. USAF kept flying the P-38's until they were condemned. Look up Lockheed P-38 Lightning in Wiki and read all about the engines. If you want to see something really cool. try finding some aerial gunnery film from a 38. Gun camera film. Those four fifties and a 20 mm. All in the nose pointing straight forwards. Simply sawed enemy planes into. They may not be on YouTube because after all it's film of men dying.

Early Spitfires with nothing but .303 guns had a hard time taking down German bombers. Not the 38's or the P'47. There is the film of the top Russian ace describing taking down JU-88's with the P-39 Aircobra. He stated something like "pull the trigger. Let up on the trigger then watch them come apart. It only took a single 37mm round to bring down a plane. Then those twin 50's mounted parallel in the nose were like a saw. Thirties in the wings just made sure no one got out alive.

[MaryB]

Saw this P-38 fly by not to long ago, hangered 20 miles away is all

[Ballistics in Scotland]

I read, in the 60s or 70, an account by two young men who met a very eay-going and friendly man in a remote bird-shooting lodge and only slowly became aware that he was Clark Gable. I think they would have found out a lot sooner about most of the film actors of today. It must have taken some such prior background to get him an air-gunner's job at an age which about made him a living fossil by aircrew standards.

Opposite direction of rotation is certainly the right way to run a high-powered twin-engine aircraft, if it isn't prevented by factor such as space, weight, parts interchangeability etc. Like many other things in aviation, it was known very early. Didn't the Wright brothers start out that way? It looks like it from the photograph, and if so it was done the right way, by the gearing.

[Artful]

If you want to see something really cool. try finding some aerial gunnery film from a 38. Gun camera film. Those four fifties and a 20 mm. All in the nose pointing straight forwards. Simply sawed enemy planes into. They may not be on YouTube because after all it's film of men dying.

Early Spitfires with nothing but .303 guns had a hard time taking down German bombers. Not the 38's or the P'47. There is the film of the top Russian ace describing taking down JU-88's with the P-39 Aircobra. He stated something like "pull the trigger. Let up on the trigger then watch them come apart. It only took a single 37mm round to bring down a plane. Then those twin 50's mounted parallel in the nose were like a saw. Thirties in the wings just made sure no one got out alive.