Author Topic: Improve the P-47 (Read 12499 times)

gripen · « **Reply #75 on:** September 29, 2006, 09:17:42 AM »

Below is a graph from article by Pappas (Flight, March 15th 1945) showing the elevator characters. Note that there might be some error in the measurements and the elevator might have been modified in the later models).

gripen

Widewing · « **Reply #76 on:** September 29, 2006, 11:06:19 AM »

Quote

Originally posted by gripen
What's the source for this? The sources seem to be quite contradictory because something like this is claimed in the AHT while White's book claim turbo in the XP-72.

White is simply incorrect. In Bodie's monster reference work on the P-47, he details the engine and supercharger installation on the XP-72. Below is a scan of the supercharger and Bodie's description from page 244 of his book.

My regards,

Widewing

bj229r · « **Reply #77 on:** October 01, 2006, 10:02:23 AM »

Quote

Originally posted by HoHun

"Adequate for the job" - funny, as the P-47 was lost its job as long-range escort fighter and was replaced by the P-51.

At the time the 51 came out, it had lots more range than the current jug. I wish they had the early jug in AH, that it might be in EW--- I simply can't fly any of the planes in there against a spit V

(p.s.--never get in an arguement with Widewing about airplanes:aok )

gripen · « **Reply #78 on:** October 02, 2006, 04:27:01 PM »

Thanks Widewing, there is not much written about the planes using the R-4360.

I've been trying to compare Republic dive data and Herb Fisher's but it seems that I should re-arrange the spreadsheet to time line based to compare the results. Anyway, the republic data seem to be near vertical dive started with half roll while Fisher just pushed the plane to the dive. Also the plane tested by Republic appear to be somewhat cleaner early series P-47 (given the weight).

gripen

Widewing · « **Reply #79 on:** October 02, 2006, 09:41:20 PM »

Quote

Originally posted by bkbandit
we need cats for our carriers, i should be able to load the hellcat, rockets 2 1000blers 100% fuel. With wind u could prob do it with out the cats but we dont have it, i have seen pics wit f6fs right before launch hooked up to cats, yea there nothin but big rubber bands but it will help.

I missed this before... You don't need a catapult, all you need is full flaps and WEP power on takeoff. Some guys will tell that they add flaps on the takeoff run, others will say they use only half flaps and wrestle into the air...

My recommendation is full flaps and WEP. No muss, no fuss, airborne without drama. 100% gas, rockets and two 1k bombs... No problem.

My regards,

Widewing

Widewing · « **Reply #80 on:** October 02, 2006, 09:59:54 PM »

Quote

Originally posted by gripen
Thanks Widewing, there is not much written about the planes using the R-4360.

I've been trying to compare Republic dive data and Herb Fisher's but it seems that I should re-arrange the spreadsheet to time line based to compare the results. Anyway, the republic data seem to be near vertical dive started with half roll while Fisher just pushed the plane to the dive. Also the plane tested by Republic appear to be somewhat cleaner early series P-47 (given the weight).

gripen

I did some additional digging into the two XP-72 prototypes. Not only did they not fly with a turbosupercharger, they never flew with that huge centrifugal blower either. That was slated for the ten YP-72s that were cancelled along with the production contract.

According to Republic's Lowery Brabham, they flew with a specially modified R4360-13 engine, fitted with a variable speed, two stage mechanical supercharger. The engine produced 3,350 hp at sea level, 2,820 hp at 25,000 feet compared to 3,000 hp and 2,400 hp respectively for the "standard" R-4360-13.

My regards,

Widewing

Magoo · « **Reply #81 on:** October 04, 2006, 01:16:02 PM »

Read somewhere on the internet and I paraphrase...

50 caliber heavy machine guns were the standard to alleviate supply chain issues with multiple types of ammo. I believe this was a deliberate decision made in the interest of simplicity, made easy by the fact that it was a good weapon.

Apparently all other issues took a back seat to this decision. What else would make sense?

I suppose that rather than giving the Jug cannon to boost it's hitting power it was just outfitted with more of the standard 50s.

Of course you could bring up the P38

but it DID have 4 50s in addition to the 20mm.

There's the added plus (and I'm guessing here) of familiarity with the weapon from plane to plane so as the squadrons were re-equipping with better planes the pilots were already familiar with the guns and knew what to expect (trajectory, velocity, distance..)

My question is - was the ammo indeed interchangeable across all 50 cal Heavy mgs in all the service branches?

Comments?

Magoo

HoHun · « **Reply #82 on:** October 04, 2006, 03:57:25 PM »

Hi Magoo,

>My question is - was the ammo indeed interchangeable across all 50 cal Heavy mgs in all the service branches?

Good question, but the rest of your posts makes me believe you have missed most of what was written above.

In short:

- The 8x 12.7 mm MGs did have about the firepower of 2 x 20 mm cannon.
- The 8x 12.7 mm MGs were about 684 lbs heavier than 2 x 20 mm cannon, with ammo and belting considered for both batteries.
- 684 lbs is about the weight of the extra fuel the P-47 would have needed in late 1943 to escort the 8th Air Force bombers all the way to Schweinfurt and back.

So the "50 cal" machine gun cost the USAAF dearly, both in terms of men and machines.

Weight in an aircraft will affect its combat effectiveness negatively, and the "50 cal" was a rather heavy weapon for the firepower it delivered.

Regards,

Henning (HoHun)

Stoney74 · « **Reply #83 on:** October 05, 2006, 01:11:51 AM »

Again, I'll ask this question, although the answer is annecdotal. Does anyone have any quotation of U.S. pilots in ETO that display "cannon envy". Almost everything I've read from U.S. pilots shows utter confidence in the firepower of the Ma Deuce. Almost all pilots talk about "superior firepower" when they compare their planes to their German counterparts. As I stated in my earlier post, this may have been a perceived advantage, but it was a uniform one. I don't doubt your math/scientific approach to comparing armament, but what did the actual pilots think? There are many examples of the U.S. using equipment that was technically "inferior" but battle tested, reliable, easily manufactured, logistically sustainable (arguably most important), and inspired complete confidence in their crew/operators.

Obviously I can't make an opinion as an actual WWII fighter pilot, but in AH, I'll take my 8X.50cal over 2X20mm any day. 4X20mm, maybe, but not just 2...

And Magoo, the answer to your question is "yes".

Stoney74 · « **Reply #84 on:** October 05, 2006, 01:23:27 AM »

Quote

Originally posted by HoHun
684 lbs is about the weight of the extra fuel the P-47 would have needed in late 1943 to escort the 8th Air Force bombers all the way to Schweinfurt and back.

Also, where you gonna stash that extra 114 gals of avgas?

http://rwebs.net/avhistory/history/p-47.htm

Wolfala · « **Reply #85 on:** October 05, 2006, 11:15:27 AM »

Quote

Originally posted by Stoney74
Also, where you gonna stash that extra 114 gals of avgas?

http://rwebs.net/avhistory/history/p-47.htm

Was about to ask the same question.

HoHun · « **Reply #86 on:** October 05, 2006, 12:02:37 PM »

Hi Stoney,

>Almost everything I've read from U.S. pilots shows utter confidence in the firepower of the Ma Deuce.

It's not like you'd have to sell the 20 mm cannon to the pilots - you'd have to sell them to the US Army.

So for the judgement of the 12.7 mm HMG's historical performance, both the question and the answer are completely irrelevant.

>There are many examples of the U.S. using equipment that was technically "inferior" but battle tested, reliable, easily manufactured, logistically sustainable (arguably most important), and inspired complete confidence in their crew/operators.

No amount of "diverse advantages" will change the basic fact that the 12.7 mm HMG was way overweight and inflicted a weight penalty of 684 lbs of extra weight over an equivalent cannon battery.

Regards,

Henning (HoHun)

HoHun · « **Reply #87 on:** October 05, 2006, 12:12:02 PM »

Quote

Originally posted by Stoney74
Also, where you gonna stash that extra 114 gals of avgas?

http://rwebs.net/avhistory/history/p-47.htm

Quote

Originally posted by Wolfala
Was about to ask the same question.

I'd suggest you two just go back a couple of messages and read the in-depth discussion of your question there.

When I'm in the right mood, I'm quite ready to provide an "executive's summary" like the one I posted for Magoo's benefit - once in a while, but not twice or thrice in succession.

Regards,

Henning (HoHun)

Stoney74 · « **Reply #88 on:** October 05, 2006, 03:55:39 PM »

See Rules #2, #4, #5

Wolfala · « **Reply #89 on:** October 05, 2006, 04:15:34 PM »

I believe the .50 debate is 2 fold: Supply chain, as pointed out earlier. The other reason is the lack of need for buff busting. The allies weren't faced with heavy armada's of bombers which required cannon to crack. And since the AXIS never developed anything along the lines of the B-17 or B-29, or fielded them in any threatening numbers - maybe it was a moot point.

Maybe Tony Williams, our resident gun author can chime in on this?

Wolf