Improve That Design: How Aircraft Could Have Been Made Better

Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules

P-39 Expert,

The test for the P-39N-1 was conducted at 7,272 lbs with ammunition in it. A stock P-39N-1 came in at 7,468 lbs. with ammunition in it. The only things that could be removed were amror, and it puts the P-39N right about the test weight. The climb test was at 50.5" MAP or full throttle, whichever is available. The U.S didn't fly them without armor or at that boost level in service, at least for a good chunk of the P-39's operational career. They flew them by the POH and squadron standard operating procedures, which weren't especially lenient about boost.

Get real. Nobody ever gets the absolute best performance ever recorded for an airplane in normal use, especially after a few months outside in the environment. There is nothing wrong with the Wright field tests. Just your determinination to use the lightweight WER Wright Field test results as normal for the P-39N, which they weren't.

But, I expect you'll stick to your guns even in the face of testimony from people who flew the P-39 that it was a dog in general. I bet in you world, stock muscle cars always run quarter miles in the quickest time ever recorded for a stock vehicle by a professional driver, too.

Not in the real world.

I had a good friend in high school who became a professional golfer. He told me once that par was the score an average professional should achieve on an average day, and that golf was the only endeavor where the average amateur participant somehow expected to be able to shoot as well as the average professional. Apparently, it isn't the ONLY endeavor where that happens.

Cheers.
 
Absolute best performance isn't top speed either, top speed is just one measure. The Spitfire Mk II was slightly slower than the MkI because that's what the RAF wanted, or rather they would sacrifice a few MPH on top speed to have an all around better aircraft.
 
Hey folks, I sense that many here are suffering from Airacobra fatigue. I know I am. How about we enter into a gentlemen's agreement to refrain from continuing to feed this beast which has devoured so many threads on this forum and diverted us from more meaningful topics? There are plenty other aircraft out there that could be improved more profitably than the P39.
What say ye?
 
Last edited:
We discussed in another thread VP props to get the Sea Hurricane into earlier service.

Earlier/better/more Sea Hurricane: pros cons
If you're going to put all the effort and weight into converting to a variable pitch propeller it's silly to not replace the actuating oil selector valve with a governor and have a full constant speed propeller system.
In practice, a variable pitch prop is essentially a two position fixed pitch prop. You can select back and forth between a "climb" prop and a "cruise" prop, but anything in between requires too much distraction of the pilot from flying and fighting, and he/she still has no protection against overreving or over-squaring (lugging) the engine.
For the ten to fifteen pound penalty of a governor, your variable pitch two position propeller can become constant speed and will hold whatever RPM you set it at, regardless of aerodynamic loads and throttle setting. Frees up the pilot for flying and fighting and maintaining situational awareness.
There's no fancy high technology or exotic production techniques in a hydraulic prop governor, which leaves attitudes and inertia as the primary reasons why it was so late in coming. Once you've flown one, it's a no-brainer.
Cheers,
Wes
 
Last edited:
For the ten to fifteen pound penalty of a governor, your variable pitch two position propeller can become constant speed and will hold whatever RPM you set it at, regardless of aerodynamic loads and throttle setting.
Keeping the early Hurricane's lower power Merlin, would this get a Sea Hurricane, especially one with the added weight of folding wings off a carrier's 500-600ft flight deck with 25-40 knots WOD? AIUI, the original fixed, two blade Hurricanes with the early Merlin would have been challenged to get off the deck, especially with the folding mechanism.
 
Yes.

Somewhere, on the internet . . . there are tests for the Hurricane Mk I when switched from the Watts 2-blade wood prop to the (Rotol? DH?) CS prop. While the top speed dropped a few mph, the TO run decreased significantly and the climb improved a bit.

edit: Found one of the tests. Hurricane Mk I at ~6300 lb TOGW had a TO roll (zero wind) decreased from 1110 ft (Watts 2-blade wood prop) , to 840 ft (DH 3-blade 2-pitch), to 720 ft (Rotol CS prop).

edit again: The TO run for the Watts was 1110 ft, it was the DH 2-pitch that had a TO run of 840 ft, so the difference was even greater
 
Last edited:
Did the See Hurricane ever have folding wings?
 
Did the See Hurricane ever have folding wings?
No, but it was probably the easiest of all the RAF's fighters to modify for them. Just need to install a hinge where the wing snaps on. This is why I want to improve the Hurricane, so that we can gain the ability to operate from carriers with narrow 22-25 ft wide lifts, like Ark Royal and Illustrious, but in 1939, not 1942 when folding Martlets, Fulmars and (eventually) Seafires canceled the need for a folding Sea Hurricane.

 
More blades will usually convert the same horsepower into more thrust at lower speeds, while fewer blades are usually more efficient at the top end. A fixed pitch "climb" prop (or a VP prop at max fine position) is generally set for just a little shy of its optimum pitch in an attempt to give the engine a little protection from over revving as the aircraft accelerates. The same thing occurs in reverse at the top end, also for over rev reasons.
A constant speed prop can have its pitch stops expanded a bit in both directions, as long as the governor's travel is limited to keep revs out of the red, thus allowing for a tad more efficiency at both ends of the spectrum.
Unfortunately, AFAIK, no one's yet come up with a variable blade count propeller to extract that last percentage point at the high end!
 
If you're going to put all the effort and weight into converting to a variable pitch propeller it's silly to not replace the actuating oil selector valve with a governor and have a full constant speed propeller system.

Yup, that Woodward C/S governor was readily available too. If only it could be built under licence, like, say, Hamilton Standard props by de Havilland... Wait a minute...
 
Yup, that Woodward C/S governor was readily available too. If only it could be built under licence, like, say, Hamilton Standard props by de Havilland... Wait a minute...
NIH Syndrome? "Bloody colonials, going gadget-happy on us again! And make us pay through the nose for the privilege! That's one gadget we can do without."
 
NIH Syndrome? "Bloody colonials, going gadget-happy on us again! And make us pay through the nose for the privilege! That's one gadget we can do without."
It's bad enough we have to fly monoplanes and have wheels with brakes, now they want us to have those heavy, expensive bloody variable pitch propellers too.

I Keep saying. 20 different airlines around the world were using constant speed fully feathering propellers in 1938. It was not a military secret or particularly expensive if airlines thought it was a good idea, profit and loss and all that.
 

Users who are viewing this thread