Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Randy1 on April 27, 2016, 05:54:41 AM
-
I am sure they had a good reason. Anybody know why they would have made this decision?
-
one problem with the counter rotating props, is that the engines are essential the same except exactly opposite, so many parts are not interchangeable. This causes supply problems.
-
Logistics more than likely. Early Whirlwind prototypes had contra-rotation props too which was even easier with the Peregrine engines. They dropped that too.
-
I am surprised that the RAF did not order P38s with two reversed engines.
That sounds a very English thing to do.
-
They wanted to use the same engines they already had for the P-40 Tomahawks so they also skipped the turbosuperchargers.
-
Weren't the turbochargers in short supply or export restricted? Seem to recall something to that effect.
Having the whole engine rotate the opposite way was a pain for supply reasons. So the two counter-rotating Rolls Royce Merlin engines fitted to the DH Hornet fighter were identical apart from the propeller reduction box fitted to the front. One of these had an extra idler gear that reversed the propeller shaft rotation. This proved useful when it was found the Hornet prototype was laterally unstable. The problem was the prop wash creating a low pressure area around the vertical stabiliser. So DH spent a couple of hours swapping the two gearboxes and props over to reverse the prop wash direction. This created a high pressure area over the stab which fixed the problem.
-
Wouldn't the extra idler in the reduction box create a slight time differential for harmonizing rpm's?
-
They wanted to use the same engines they already had for the P-40 Tomahawks so they also skipped the turbosuperchargers.
(http://www.donorschoose.org/images/misc/opendata/big_winner.jpg)
-
Wouldn't the extra idler in the reduction box create a slight time differential for harmonizing rpm's?
I would have thought the difference would be negligible, probably less than that between engines of varying ages. Twins generally had a control to let the pilot tune out the variation.
-
They wanted to use the same engines they already had for the P-40 Tomahawks so they also skipped the turbosuperchargers.
I wonder then when they ordered the P-38s, what role did they have in mind for the plane?
Thanks for the replies.
-
I wonder then when they ordered the P-38s, what role did they have in mind for the plane?
Thanks for the replies.
Evaluation as a fighter.
-
Evaluation as a fighter.
Must have been evaluated for low altitude interceptions I would guess.
-
Must have been evaluated for low altitude interceptions I would guess.
The aircraft was likely evaluated against the current threat and compared to the current available fighter inventory. WW2 started with biplane fighters still in service and finished with jets. Early orders didn't anticipate the rapid pace of development.
-
The aircraft was likely evaluated against the current threat and compared to the current available fighter inventory. WW2 started with biplane fighters still in service and finished with jets. Early orders didn't anticipate the rapid pace of development.
Damn, you're on a roll! You explained it pretty well.
-
Damn, you're on a roll! You explained it pretty well.
:rofl :aok Go FLS
-
Doggone we need a big gold star icon.
That does make perfect since FLS.
Often you read post that make the Brits P-38 build choice look like a really dumb idea. I figured that they had to have a good reason for the Brit build to suit the moment the decision was made. I just did not know the whys.
Thanks everyone.
"Now we know the rest of the story."
-
Both the British and French delegations insisted that the Lockheed fighters be equipped with Allison engines without turbosuperchargers and with strictly right-handed rotation. This was because they wanted the engines to be interchangeable with those of the Curtiss H.81A Tomahawk which had been ordered by both Britain and France in great numbers. In addition, the Committee wanted to optimize the aircraft for medium-altitude combat as was currently the dominant mode of aerial warfare in Europe, rather than the high-altitude role for which the P-38 had originally been designed. The Anglo-French delegation was also aware of the problems currently being experienced by the War Department in the delivery of turbosuperchargers, and did not want to run the risk of costly, time-consuming delays since they wanted all the planes delivered in less than a year. It turned out that this decision was particularly unfortunate.
http://www.joebaugher.com/usaf_fighters/p38_7.html
-
I am sure they had a good reason. Anybody know why they would have made this decision?
:airplane: There is no difference in engines running with right hand rotation or left hand rotation, its a matter of setting the timing of the ignition system to make it run which ever way you want it to.
The problem comes with all the "gear'" driven accessories, such as fuel pumps, oil pumps and etc. The "blowers" are not effected because they are exhaust gas driven!
The fuel pump and oil pumps had to be redesigned and produced for the "left" hand rotation, as was generators and other gear driven accessories, so I think that had a big influence on their decision because they want the English manufactured engines, but RR wasn't able to "retool" for the different rotation of accessories, which made delivery of the 38's a lot quicker!
-
Evaluation as a fighter.
:airplane: Ground support and Recon~!
-
If R-R wasn't able to retool then how did they make their opposite rotation engines for a/c like the Hornet?
-
If R-R wasn't able to retool then how did they make their opposite rotation engines for a/c like the Hornet?
:airplane: You have raised a good point and not sure how RR did what, but making a inline engine run in the direction you want is no big deal, except for the gear driven equipment in the accessory section of the engine. And of course the prop, which I think only had to have the blades rotated 180 degrees on the hub
-
Most of the P-322s ended up at RTU units as trainers. Stan Richardson was an RTU instructor and logged quite a few hours in them. He didn't like them, finding the P-322 notably inferior to the P-38F and G models they later received.