The 1.05 planes

[Westy]

I promise to use them only at night  

-Westy

[F4UDOA]

Hmm,

The confusing thing about the Jug's climb rate isn't that it was supercharged. Remember all Jugs were supercharged from the very early to the very late. The riddle to solve on the Jug's climb rate was this.
The P-47D20 through the P-47D produced only 2300HP. The D20 climbed at no more than 2500FPM with water injection. However with No change in engine HP the P-47D25 climb performance was increased at combat power to 3400FPM with only a propeller change to a wide chord prop Hamilton Standard Prop. So the Supercharging really had nothing to do with the increase in the Jugs performance.
By comparison the F4U also changed to a wide chord HS prop(it was a three blade prop)with an increase in performance that is only noted in the flight test performed against other A/C ie. the P-51B and FW190-A5. No where in the performance specs will you see this noted. I believe somewhere there should be a sperate performance chart for the increased performance. The change of prop however is noted in the pilots manual for use whenever possible because it Quote "improves performance".

Funked,

From the F4U-1D pilots manual.

War emergency power
RPM  Manifold pressure  Horse Power Alt.
2700      57.5           2250HP     Sea level
2700      59             2135HP     15,000FT
2700      59.5           1975HP     20,000FT

The Hellcat also had the same engine ratings. For whatever reason many sources choose to qoute this incorrectly.

Later
F4UDOA

[funked]

DOA I thought D-25 was the first Jug with Water Inj?  Talking with Gabreski about it, he thought the combination of the water injection and the prop made a huge difference.

I don't think a D-25 should climb any better than an F4U-1D at sea level.  I would expect the D-25 to climb better at higher altitudes as the Hog's HP fluctuates up and down while the Jug power stays constant.

I think you might be right that the Navy figures are conservative.  But I don't think they are conservative by too much.  As far as head to head tests, I am wary of them.  They are usually conducted by people with an agenda.  Also they are highly variable.  I can give you a reference to a climb test where a P-39D and A6M smoked an F4U-1D.

Thanks for the clarification on the power for R-2800-8W and R-2800-10W.

[Ripsnort]

Funked, Personal agendas !?!  Never! (LW conspiracy comes to mind, hehe)

I'm just curious as to why the P47 climbs  so  dang good compared to WB's jug, is theres really that  under-modeled or ours over-modeled?

[funked]

Climb vs. altitude and speed vs. altitude on WB planes are off badly in many cases.  Some of them are pretty close but some are off in left field.

[F4UDOA]

Funked,

You are right about the P-47D becoming superior at Higher alts in climb compared to both Corsair and Hellcat. But I'm thinking more of 25K and over. That is right about the altitude where the power to weight begins to favor the P-47.

As far as the water injection I am looking at America's Hundred Thousand for my reference. Water injection started in the  
P-47D-5 raising Max HP from 2000HP to 2300HP.

If you have that flight test data on the A6M, P-39 and F4U I would Luv to see it. Please Email it to me. However I have flgith test data on the A6M-2 and A6M-5 where the F4U-1 and -1D are equal up to about 10K and then superior above reaching 20K faster. The P-39 was faster initially to 5K but then fell off at 10K and was a dog by 15K. That really doesn't surprise me based on power to weight at sea level. My reference is in the "Warbird History" Combat and Developement of the Zero. An excellent book with some great photo's.

Later
F4UDOA

PS. Please email me any additional flight test data you might have.

[Jigster]

 

Originally posted by F4UDOA:
Funked,

You are right about the P-47D becoming superior at Higher alts in climb compared to both Corsair and Hellcat. But I'm thinking more of 25K and over. That is right about the altitude where the power to weight begins to favor the P-47.

As far as the water injection I am looking at America's Hundred Thousand for my reference. Water injection started in the  
P-47D-5 raising Max HP from 2000HP to 2300HP.

If you have that flight test data on the A6M, P-39 and F4U I would Luv to see it. Please Email it to me. However I have flgith test data on the A6M-2 and A6M-5 where the F4U-1 and -1D are equal up to about 10K and then superior above reaching 20K faster. The P-39 was faster initially to 5K but then fell off at 10K and was a dog by 15K. That really doesn't surprise me based on power to weight at sea level. My reference is in the "Warbird History" Combat and Developement of the Zero. An excellent book with some great photo's.

Later
F4UDOA

PS. Please email me any additional flight test data you might have.

Well keep in mind the P-39 and all the Zero's had no way of generating extra power as air density decreases. The F4U, F6F, etc all had a two stage charger, where the first stage was developing more power then the engine would be without it, even in the 14-19k zone where power loss is the greatest.

Thus the planes without it are decreasing in horsepower in the power to weight ratio as they increase in altitude. So the Zero would be comparible up to the point where the power loss from altitude causes it to fall behind in power to weight.

And didn't the 4 blade Hamilton Standard actives on the P-47's run at a higher RPM then the 3 blade on the Corsair?

- Jig

[F4UDOA]

Jig,

I agree on your point about the blower shift points being the area of highest HP before it begins to drop off. Here is a link to the P-51B vs the F4U-1(modified) and F4U-1A(unmodified). It clearly shows the availbe Hp of the F4U-1A being right at or above 2000Hp all the way up to 20K
 http://members.home.net/markw4/index2.html

Also the RPM on the P-47 was 2700 which is the same on the F4U. Referance is America's Hundred Thousand for both. Which leads me to believe since prior models of the P-47D-5 through D23 all had 2300HP as well as the same Supercharger that the increase in climb is due to the prop.

By contrast I have never seen a correction chart for increased performance in the
F4U-1D. I believe this is because the F4U-4 was under test at the time using the same blade type as was being installed on the
-1D(Type 6501A-0). They probably did not see a need to go back and benchmark the A/C again for that reason. I guess they didn't forsee the future where techno-geeks would argue the virtues of their favorite A/C until blue in the face.

Note the prop change notice in section
C.Drag condition
Also look at the F4U/F6F vs FW190A5 for another reference to the prop change and incresed performance.
 http://members.home.net/markw4/FW190_F4U.html

Later
F4UDOA

[SageFIN]

While we are discussing supercharging, I'd like to know what you people think of the following quote:

"While the conventionel mechanical superchargers consisted of one or two compressors driven via a two-speed gear, Daimler-Benz utilised an ingenious barometricly controlled hydraulic clutch which adjusted the compressor speed and thus the charging of the engine according to the needs at a given altitude.

The conventional method results in a relative loss in efficiency below rated altitude, because the compressor uses energy to produce surplus charging. A graphic presentation of engine output relative to altitude would show a "saw-touth" line: the output in low gear rising with altitude until reaching the rated altitude, then output falls until the high gear kicks in, when the output again rises the rated altitude is reached.

In comparison the Daimler-Benz system is more flexible. A graphic presentation would show a smooth shallow curve. A source of efficiency loss with this system being progressive heating of the oil as pressure in the clutch builds with altitude."

I found this quote at the following URL: http://w1.1861.telia.com/~u186104874/db605.htm

If this is true, then shouldn't it mean that the speed/climb curves for the 109s should be smooth and not jagged as they are now?


------------------
---
SageFIN

"The wolves are gathering, the stars are shifting...
come, join us in the hunt!"
---

[Hamish]

 

Originally posted by Nath-BDP:
The only F6F witn 20mm was the F6F5N, which was a nightfighter.

Nath, we hashed out the 20mm/.50 cal issue in this thread: http://bbs.hitechcreations.com/smf/Smileys/default/Forum9/HTML/000623.html

I recomend hitting the links for the info on the F6F, it's a U.S. navy document and while not stating any numbers of aircraft sent to the fleet with 4x.50 2x20mm, it implies that there were some manufactured in that manner, and not just the -5n (night fighter)

[edit]
After re-reading Westy's post, His link is one we looked at irt the armament issue. It's a declassified navy document.
[edit]

Hamish!



[This message has been edited by Hamish (edited 09-22-2000).]

[Major Tom]

The F6F sure is a cute 'lil plane.  It reminds me of what a P-47C might look like if left out in the rain too long and it shrunk slightly.

I'm sure the F6F will supplement the spit as the newbies delight, it's one of those "well rounded" aircraft.