Allied Gold-Match II

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Soren said:
As for the Spit Mk.21 and F8F Bearcat.

RG the Normal loaded weight for the Bearcat was 9,386 lb, and its wing area 244 sq.ft. The Spit Mk.21's normal loaded weight was 8850 lb, and its wing area was 244 sq.ft !
Click to expand...

Where do you get that data from? The combat weight I have found for the F8F-1 is 8800 lbs, ~9400 lbs with a drop tank. For the F8F-2 the weight goes up to about 9400 lbs clean. The weight I gave for the Spitfire 21 was from the Spitfire performance testing site - which gives 9305 for the plane tested, but some lower wieghts as well, so I split the difference and used 9250 lbs.

I've arranged to get the Pilot Handbook for the F8F - I should have it in a few days. It should include the combat weight of the plane (if it includes both -1 and -2 data).

Soren said:
And according to my sources, the Spit 21's new wing gave greater lift !
Click to expand...

By what magic? It's the same airfoil. I've given you the NACA airfoil numbers for the wing, they are identical to those of the earlier Spitfires. Same airfoil, same wing area, same lift.

=S=

Lunatic
 
Once again you do not read very well do you?
Click to expand...

RG, your the one who forgot something !

RG explain to me why would a Spit weighing 9,000 lbs rated to climb at 7.85 min be faster than a Spit weighing 8850 lbs ? The Spit 21's normal weight was 8850 lbs, so it would actually climb faster.

The source Soren?
Click to expand...

The bloody 4th fighter group site !! But to make it easy for you:

http://www.spitfireperformance.com/spit14afdu.html

http://www.spitfireperformance.com/spit9tactical.html

You are the one who has pointed to wingloading over and over again to support your "this plane must turn better than that plane" arguments.
Click to expand...

No RG, that was infact you ! And you forgot Power-loading !

But most of all, pilot accounts relate that the Spit V was the best handling of all the versions of the Spitfire and that later models did not manuver as well because of the increase in weight.
Click to expand...

Just ONE example please. According to all my available accounts the controls got heavier, but maneuverability was better !
 

RG the F8F-1 already weighes 7,070 lbs EMPTY ! Normally loaded (Without Drop-tank) it weighes 9,386 lbs, and max loaded it weighes 12,947 lbs.

I've arranged to get the Pilot Handbook for the F8F - I should have it in a few days. It should include the combat weight of the plane (if it includes both -1 and -2 data).
Click to expand...

Right now Im looking at a book supposedly based on it !

By what magic? It's the same airfoil. I've given you the NACA airfoil numbers for the wing, they are identical to those of the earlier Spitfires. Same airfoil, same wing area, same lift.
Click to expand...

Why havent you given me a source then ? A link, anything !

My source tells me the new wing provided more lift, so until you give me some solid evidence that it didnt, Im gonna have to stick to that.
 

The 7.85 minute to 30k time is a 1943 factory figure relating to a prototype. Most likely it is an estimate based upon partial tests, bench tests, or the slide rule. It has no bearing on reality, especially since the actual flight tested data from a production unit is available.

I've not seen that weight for the Spit 21 - where do you get it from?


Okay, I'll conceed that the Spit V/IX/XIV all turned about equally well. It really does not matter to the point being made, which concern's the Sptifire vs. Bearcat turning capability.

Here's a quote on the relative turning capability of the Hellcat, Bearcat, Spit V, and Zero:


Here's a quote concerning the Zero vs. the Spit V:


The F6F tests were carried out at Boscomb Down in (March?) 1943. I'm trying to track down the actual tests (if they are available).

But the point is pretty clearly made. The F6F could turn with the Spit V, the Zero could out-turn it, but the Bearcat could out turn them both!

The Bearcat could also roll nearly as well as an FW190 - which was studied carefully by Grumman in its development the Bearcat.

=S=

Lunatic
 

The test data I've seen (and posted) shows 8800-9000 lbs for the F8F-1 at combat weight.


I have, but I'll give it to you again:

UIUC page: http://www.aae.uiuc.edu/m-selig/ads/aircraft.html

This page explains how to interpret the NACA airfoil numbering system:

http://www.allstar.fiu.edu/aero/Wing31.htm

The UIUC webpage gives the airfoils for a large number of Aircraft, including the Spitfires, Corsair, and Bearcat. Search it for "Spitfire 21" and you will see there was no change in the airfoil used. The only difference that might add a tiny bit of lift would be that the wing was not quite so eliptical, it didn't come to a point out at the very tip, it was squared off. This would mean there'd be a little more chord further out on the wing which might give a little bit more lift - but not a huge amount.

Soren said:
My source tells me the new wing provided more lift, so until you give me some solid evidence that it didnt, Im gonna have to stick to that.
Click to expand...

Done!

=S=

Lunatic
 
First of all, the any of the three Spitfire's would trash an F6F Hellcat in a T&B fight. (Just take a look at the stats !)

Secondly I don't believe anything that site says as I personally own two of the books he "Says" he uses as sources (Grumman : Sixty Years of Excellence. for one), and none is mentioned about the F6F matching the Spit in a turn !



Wrong RG, they are based on tests with the aircraft as explained:

Spitfire F. Mark 21 - Griffon 61 Performance Tests Of Prototype DP.851

Summary of Results

At an all-up weight of 9000 lb. and with combat rating of 2750 r.p.m. and 18 lb. boost:

(a) Maximum level speed 455 m.p.h. at 25,600 ft.
(b) Maximum rate of climb 4800 Ft./Min. at 7700 ft.
(c) Time to 30,000 ft. 7.85 mins.
(d) Service ceiling 42,800 ft.
(e) Coolant and oil suitabilities: Full tropical under combat climb conditions.

And more details:

1. Introduction.

This report summarizes the results obtained on the prototype Mark 21 fitted with a Griffon 61 engine.

2. Summary of Results

At an all up weight of 9000 lb. and wtih combat rating of 2750 r.p.m. and 18 lb. boost:-

(a) Maximum level speed 455 m.p.h. at 25,600 ft.
(b) Maximum rate of climb 4800 Ft./Min. at 7700 ft.
(c) Time to 30,000 ft. 7.85 mins.
(d) Service ceiling 42,800 ft.
(e) Coolant and oil suitabilities: Full tropical under combat climb conditions.


3. Condition of Aircraft

(a) Griffon 61 engine No. 1266 fitted with a .45 airscrew reduction gear.
(b) 11 ft. 0 in. dia. 5 blade Jablo Rotol airscrew with faired roots. Blades to Drg. No. RA.10129/JJ.
(c) Morris type QEW (port and QEY (starboard) radiators.
Morris type QEV intercoller radiator.
Morris type QEZ oil cooler.
The duct static exit areas are: closed mean 0.76, open mean 2.02 sq. ft.
(d) Tropical type of air intake to Drg. No. 35638 Sht. 35 was fitted.
(e) Multi-ejector exhausts fitted.
(f) Windscreen with a curved front panel as on production rear view fuselage.
(g) T.R.1133 whip type aerial fitted.
(h) Undercarriage-wheel flaps fitted for final flight. Retractable tail wheel.
(i) Four 20 m/m cannon armament.
(j) All up weight 9000 lb. C.G. 3.3" inches aft of datum.


4. Reduction of Results

Results have been reduced to I.C.A.N. standard conditions in accordance with A.D.M. 555.

5. Results

The results are shown on Figs. 1-4
 
It says that performance tests were done, but there is no indication that actual full flight tests were done. And besides it's a prototype, not the real thing!

The tests of the real thing are there for you to see. Why do you ingore 1945 AAEE production model tests in favor of 1943 factory prototype tests which give no detail and could well be estimated performance based upon partial climbs and partial speed tests, and which bear almost no relation to the tests carried out on the actual production unit? It just doesn't make sense!
 
Soren,

Luni is correct, this time, for the Spit XIV and the Spit 21 used the same NACA 22 series airfoil, as did all Spits from the Mk I.

...................

Spit XIV
Fin area - 4.51ft2
Rudder area - 8.23ft2, later 10.08ft2
 
KraziKanuK said:
Soren,

Luni is correct, this time, for the Spit XIV and the Spit 21 used the same NACA 22 series airfoil, as did all Spits from the Mk I.

...................

Spit XIV
Fin area - 4.51ft2
Rudder area - 8.23ft2, later 10.08ft2
Click to expand...

Yes the airfoil shape was the same, but i doubt the thickness.

In any case wing thickness differences of only 1-5% gives only VERY little extra lift !

The Typhoon and Tempest are good examples of this, as their wings were amongst the thickest put on any Single-piston-engined a/c, yet their turn performance wasnt good at all. The Typhoon being only a tiny bit better in turning circles than the Tempest because of its 19% airfoil vs Tempest 14% airfoil thickness, but the difference is barely there.

Tempest:

Power: 2,180-2,420 hp
Wing Area: 302 sq.ft
Normal Loaded weight: 11,400 lbs

Typhoon:

Power: 2,180-2,420 hp
Wing Area: 278 sq.ft
Normal Loaded weight: 11,780 lbs

Stall speed for both aircraft was around 87-89 mph.

TEMPEST V TACTICAL COMPARISON WITH TYPHOON IB

Turning Circle
Very Similar. Any difference appears to be in favour of the Typhoon. This is too slight to alter combat tactics.

TEMPEST V COMBAT TRIALS AGAINST SPITFIRE XIV

Turning Circle
The Spitfire XVI easily out-turns the Tempest.
 
Soren said:
RG_Lunatic said:
Done!
Click to expand...

RG the Spit Mk.XXI isnt there !
Click to expand...

Grrrr. Try again. This time search on "Spitfire 21", not "Spitfire XXI". The site accurately uses 21 rather than XXI since starting with the 21 Supermarine chose to switch to arabic rather than roman numbering.

The following Supermarine aircraft are listed....

Code: 
Conventional Aircraft:                       Wing Root Airfoil               Wing Tip Airfoil
 Supermarine 179 Giant                        RAF-34                          RAF-34
 Supermarine 224 F7/30                        NACA 0018                       RAF-34
 Supermarine 300 Spitfire I                   NACA 2213                       NACA 2209.4
 Supermarine 316 B.12/36                      NACA 22??                       NACA 22??
 Supermarine 317 B.12/36                      NACA 22??                       NACA 22??
 Supermarine 318 B.12/36                      NACA 22??                       NACA 22??
 Supermarine 329 Spitfire II                  NACA 2213                       NACA 2209.4
 Supermarine 331 Spitfire VA                  NACA 2213                       NACA 2209.4
 Supermarine 337 Spitfire F IV                NACA 2213                       NACA 2209.4
 Supermarine 340 Seafire IB                   NACA 2213                       NACA 2209.4
 Supermarine 348 Spitfire III                 NACA 2213                       NACA 2209.4
 Supermarine 349 Spitfire VB                  NACA 2213                       NACA 2209.4
 Supermarine 350 Spitfire HF VI               NACA 2213                       NACA 2209.4
 Supermarine 351 Spitfire VII                 NACA 2213                       NACA 2209.4
 Supermarine 352 Spitfire VC                  NACA 2213                       NACA 2209.4
 Supermarine 356 Spitfire 22                  NACA 2213                       NACA 2209.4
 Supermarine 357 Seafire F IIC                NACA 2213                       NACA 2209.4
 Supermarine 358 Seafire F III                NACA 2213                       NACA 2209.4
 Supermarine 359 Spitfire VIII                NACA 2213                       NACA 2209.4
 Supermarine 360 Spitfire VIII                NACA 2213                       NACA 2209.4
 Supermarine 361 Spitfire IX                  NACA 2213                       NACA 2209.4
 Supermarine 362 Spitfire PR X                NACA 2213                       NACA 2209.4
 Supermarine 365 Spitfire PR XI               NACA 2213                       NACA 2209.4
 Supermarine 366 Spitfire F XII               NACA 2213                       NACA 2209.4
 Supermarine 368 Spitfire 21                  NACA 2213                       NACA 2209.4
 Supermarine 368 Spitfire VIII                NACA 2213                       NACA 2209.4
 Supermarine 369 Spitfire F XIV               NACA 2213                       NACA 2209.4
 Supermarine 371 F 14 Spiteful                Supermarine 371-I               Supermarine 371-II
 Supermarine 372 Valiant F 23                 NACA 2213                       NACA 2209.4
 Supermarine 373 Spitfire F XIV               NACA 2213                       NACA 2209.4
 Supermarine 375 Seafire L IIC                NACA 2213                       NACA 2209.4
 Supermarine 376 Spitfire VIII                NACA 2213                       NACA 2209.4
 Supermarine 377 Seafire F XV                 NACA 2213                       NACA 2209.4
 Supermarine 378 Spitfire IX                  NACA 2213                       NACA 2209.4
 Supermarine 379 Spitfire F XIV               NACA 2213                       NACA 2209.4
 Supermarine 380 Spitfire F XVI               NACA 2213                       NACA 2209.4
 Supermarine 381 Seagull                      NACA 23018                      NACA 3410
 Supermarine 382 Seafang F 31                 Supermarine 371-I               Supermarine 371-II
 Supermarine 386 Seafire F XV                 NACA 2213                       NACA 2209.4
 Supermarine 388 Seafire F 45                 NACA 2213                       NACA 2209.4
 Supermarine 389 Spitfire PR XIX              NACA 2213                       NACA 2209.4
 Supermarine 390 Spitfire PR XIX              NACA 2213                       NACA 2209.4
 Supermarine 392 FB Mk2 Attacker              Supermarine 371-I               Supermarine 371-II
 Supermarine 393 F 16 Spiteful                Supermarine 371-I               Supermarine 371-II
 Supermarine 394 Spitfire F XVIII             NACA 2213                       NACA 2209.4
 Supermarine 395 Seafire F XVII               NACA 2213                       NACA 2209.4
 Supermarine 396 Seafang F 32                 Supermarine 371-I               Supermarine 371-II
 Supermarine 474 Seafire F 47                 NACA 2213                       NACA 2209.4
 Supermarine 505                              ? 7% symmetrical                ? 7% symmetrical
 Supermarine 506 Seafire LF III                NACA 2213                       NACA 2209.4
 Supermarine 508                              ? 7% symmetrical                ? 7% symmetrical
 Supermarine 521 Spitfire T VIII              NACA 2213                       NACA 2209.4
 Supermarine 529                              ? 7% symmetrical                ? 7% symmetrical
 Supermarine 545                              RAE 103                         RAE 103
 Supermarine Seamew                           Gottingen 387                   Gottingen 387
 Supermarine Sparrow Biplane                  RAF-15 (upper)                  AD 1 (lower)
 Supermarine Sparrow Monoplane                Clark Y                         Clark Y
 Supermarine Sparrow Monoplane                T 64                            T 64
 Supermarine Sparrow Monoplane                RAF-30                          RAF-30
 Supermarine Sparrow Monoplane                SA 12                           SA 12
 Supermarine S-5                              RAF-30                          RAF-30
 Supermarine S-6                              RAF-27                          RAF-27
 Supermarine S-6B                             RAF-27                          RAF-27

As you can see ALL SPITFIRES USE THE SAME AIRFOIL!

=S=

Lunatic
 


Soren, read the above, it expains how to interpret the NACA airfoil numeric code. The chord of the Spitfire 21 wing did not increase at the root, it increased near the tip it was a rather minimal change (from looking at photos). Since the last two digits of the airfoil indicate thickness as a percentage of chord, which for the Spitfire is 13% at the root and 9.4% at the tip, there would be almost no change in wing thickness.

Soren said:
In any case wing thickness differences of only 1-5% gives only VERY little extra lift !
Click to expand...

Glad you realize this... now apply this knowlege to your prop efficiency near the root argument!



Well, lets look at the airfoils...

Code: 
 Conventional Aircraft:               Wing Root Airfoil         Wing Tip Airfoil
 Hawker Tempest                       H/1414/37.5 (14%)         H/1410/37.5 (10%)
 Hawker Typhoon                       NACA 2219                 NACA 2213

I have no idea how to interpret the Tempest airfoil encoding, it is not NACA. However, it seems extremely likely that it is 14% of the chord thickness at the root and 10% at the tip.

The 19% thickness at the Typhoon root is HUGE... I have to wonder how fast it tapered off toward 13%, I would bet it did so rather quickly. Assuming the 14%/10% values for the Tempest wing it makes sense the Typhoon would turn a little better, despite its higher weight.

Given the 33% higher weight of the Tempest/Typhoon, it is not at all surprising the Spitfire XIV would out-turn them.

Just my opinion, but I think that lift from the wings is more significant for lower speed turns, the ability to achieve angle of attack via the tail surfaces becomes increasingly significant with increasing speed, where angle turning becomes more important than sustained turn rates.

=S=

Lunatic
 
The Tempest used a 'laminar' airfoil. Max chord was at 37.5%.

The Typhoon's wing had a slight anhedral inner section (to the u/c pivot point) and a dihedral outer section. The bottom of the inner section was horizontal with the upper surface slanted downwards to the join point of the outer section.
 
Glad you realize this... now apply this knowlege to your prop efficiency near the root argument!
Click to expand...

RG there's a difference betweeen having two airfoils with a 1-5% in thickness difference, and having some with a 50% thickness difference !



Glad you realized this, now apply this to the Spit XIV vs Corsair arguement !

The only airfoil shape that has any real impact on lift is the "Laminar" airfoil, wich although reduces drag significantly also reduces lift, especially in turns ! This explains why the Typhoon barely outturned the Tempest, the thickmess difference between the wings has nothing to do with it, however the shape does !
 
Ummm.. a 15% thickness airfoil IS 50% thicker than a 10% thickness airfoil, given the same wing chord. The Typhoon wing is almost TWICE as thick (well, 190%) as the Tempest airfoil (assuming the chords are the same).

I disagree. Both things contriubute to the Typhoon out-turning the Tempest.
 
Ummm.. a 15% thickness airfoil IS 50% thicker than a 10% thickness airfoil, given the same wing chord. The Typhoon wing is almost TWICE as thick (well, 190%) as the Tempest airfoil (assuming the chords are the same).
Click to expand...

My fault, it should have been 500%, and to illustrate it, look at the bottom of the page. (Those two prop-airfoils have a thickness difference of approx.300% !)

I disagree. Both things contriubute to the Typhoon out-turning the Tempest.
Click to expand...

Offcourse, but it is the "Laminar" airfoil shape that takes away most of the lift.
 

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Btw RG, by looking through your presented airfoil site, I found out that it is just flat wrong about alot of airfoil data !

For example the Lavochkin series according to all my sources used the NACA 23012 root profile, but according to your presented site it is an insane 23016 !!

According to your presented site the Lavochkin series had a thicker wing than both the F4U Corsair and the F6F Hellcat, wich clearly isnt true ! ( If you aint convinced, then look at the pic's below )
 

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Well, I think that depends on where exactly you measure it. If you look closely the La7 wing does get very very thick right at the root, but it tapers off very quckly to a less thick airfoil just a short distance from the fuselage. Different standards of measurement may be the cause - some measure right at the root just inches from the join to the fuselage, others consider the root to be at 10% out from the join, and the tip to be 90% from the join. While the normal specification seems to be a root airfoil and a tip airfoil, the area in between obviously transitions a number of intermediate airfoils to get from the one to the other.

Right at the actual join (which is spread across the bottom of the plane), the La7 wing might indeed be as thick as that of the Corsair, its chord is only slightly more but probably more than 1%. 10% out from the root, the chord of the La7 wing has diminished significantly and quite possibly the airfoil has already reduced from 16% to 12% thickness. The combo of both factors would make the wing look much thinner in the photos you've provided.

Alternatively the site has wrong data for the Lavochkin airfoils. Why don't you email the webmaster and ask?

What other airfoils do you think are incorrect? I would expect the Russian airfoils to be the least reliable in the list for obvious reasons.

=S=

Lunatic
 
Alternatively the site has wrong data for the Lavochkin airfoils. Why don't you email the webmaster and ask?
Click to expand...

I have problems with my E-mail program, wich just out of the blue stopped working 2 weeks ago

What other airfoils do you think are incorrect? I would expect the Russian airfoils to be the least reliable in the list for obvious reasons.
Click to expand...

Actually your expectations are well grounded, as it is mostly Russian airfoil data that is incorrect, but also a few Jap airfoil data.
 
I heard that the Bearcat had explosive bolts on it wings so that it could blow of its outer wing panels to increase roll rate in a dogfight. Is this true?
Was it a secret weapon system designed to fling pieces of wing at the opposing aircraft?
 
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