Letīs talk about the tempest

[Vermillion]

FdSki wrote:
 

Heheheh can't live with the fact that US planes weren't the best ?

Blah blah... blah blah blah  

Give me a late model Yak-3, one of the ones powered with the VK-107 engine, and then we'll talk. Or even a Yak-3P.

Hell look at the controversy that the La7 is causing because its faster on the deck than both the Fw190D, the Typhoon, and the P51D.

The Yak3/Vk107 was infinitely more wicked.  


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Vermillion
**MOL**, Men of Leisure

[Sable]

Here's an easy way to test if your Tempest is turning too well:  test it's 1g level, power-off stall speed.  Make sure you do this with a full load of fuel and ammo too.  According to the RAF pilots notes it should be ~106-108mph IAS.  If you are getting numbers substantially lower then this, then either it's weight is too low, or it's wing is producing too much lift.  Simple as that.

Sable
352nd FG

[niklas]

@buzzbait
 

I would suggest you do some more research on the Tempest

itīs not so easy buzzbait. Look at funkedīs chart, so many different engines. And i canīt see a 2180hp number there, but a 2090hp number   (normal power)

 

In addition, the British did not test the Mustang III with the rear fuselage 85 gallon tank full.

This is no surprise to me. The P51 was close to instabillity with this fuel tank. Impossible to do real manoevering with this fuel tank.

 

The Tempest was a much cleaner aircraft than the Focke Wulf 190, it was able to get much more out of a unit of horsepower than the German aircraft

With all respect, are you blind? Canīt you see this huge oilcooler under the nose?? Clean design - LOL. And even with this huge oil cooler, the sabre engines suffered from overheating....
And a FW190D needed 2240hp for 375mph, the Tempest with a thin laminar wing (!!) was as fast with the same horsepower (sabre IIa +9 boost), 378mph with 2235 HP.

If you look at funkedīs chart, you can see that the sabre also got itīs power from the boost. With +10 or +12 boost, it used smiliar boosts like usual german engines. Of course did the engine run very fast - almost the same volume like a Jumo engine, but 24cylinder instead of 12 for the Jumo. The volumes and sizes of the components were smaller, which allowed higher RPM. On the other hand, the Sabre was a lot heavier and used a lot more fuel.
The really interesting point is that the Sabre engine didnīt had usual valves for the cylinder inlets and outlets, but used some "slides-technics" (donīt know how to explain it   )

When the tempest was +50mph faster than the A4, then you know which power setting was used for the A4...

And yes i compare sustained turn rates. Another good hint that the Typhoon was slightly better. Was the Typhoon a good turnfighter?


@vermillion
Yes. And from the link in this page i got the AFDU test results.


@funked
 

It makes perfect sense DOA.

Youīre right, but the initial climbrate is imo too good. Well a test pilot canīt test a sustained climbrate near sealevel   (initial climbrates from flight tests are often excellent, maybe theyīre the result of a little zoom climb at the beginning?? )

niklas

 

[funked]

I don't think 4500 fpm is unreasonable for a plane with under 4.5 lb/hp.

It's about as unreasonable as an 8500 lb, 1700 hp Fw 190 doing 4000 fpm like the USAAF found and like we have in AH.    

[This message has been edited by funked (edited 03-20-2001).]

[Nashwan]

 

And a FW190D needed 2240hp for 375mph, the Tempest with a thin laminar wing (!!) was as fast with the same horsepower (sabre IIa +9 boost), 378mph with 2235 HP

That speed is for a Tempest Series 1 with Hispano II so extra drag from the cannon barrels. More importantly that is with a Sabre IIA producing 2090HP not 2235hp.
So yes, the Tempest is a cleaner design. It went faster with less power suggests it was cleaner to me.

[Buzzbait]

S!

Top speed of Tempest at S.L. was 392mph on 2435 hp.  As compared to the FW190D at 382mph without ETC 504.  So obviously the Tempest is getting more speed per horsepower at S.L.  The Tempest's engine is not optimized for higher altitudes, yet it still gets 435mph to the FW190D's 440 without ETC 504.

Drag is not primarily a function of the nose area of an aircraft.  Having a large radiator is more than compensated for by the fact the Wings are laminar flow.

[F4UDOA]

Funked,

Yes it does drop down to 2500FPM, but at 15k it is still over 2700FPM. At 18K it finally hits 2380fpm. But when you compare it to more modest climbers like the P-47D, F4U-1 or F6F-5 all of which can reach 20k in aprox. 7.5 min or less. It just seems odd that it doesn't have more than a one minute advantage to 20K over any of these birds. I think it is the method of testing that leads to the varience. This isn't really an AH issue as much as one for history. Notice in testing against a FW190-A series the 190 out climbs the Tempest? This should not be possible.

All of the A/C times are tested using max continuous power up until the time it is required to switch to normal power. Something which is not modeled in AH but will be in an upcoming simm with Sea Fury's and F4U's  . However if you look at the climb curve for the F4U-1D and compare it to the curve of the Tempest it would appear as if the Tempest would reach 20K more than approx 40secs time differance.

 

Notice the F4U reaches gives up over 1K per minute for almost 10K
 

I wonder if someone has tested the Tempest in AH time to 20K??

[Buzzbait]

S!

The link above to the Tempest test data is with a Napier Sabre IIa engine.  All Tempests were subsequently equipped with the IIb engine.  The IIa is the original Typhoon engine and was obviously being used in the Test aircraft.  As indicated by Funked's chart, there is a considerable difference in Hp output between the two.

[Nashwan]

Did a quick test offline on the Tempest. Full fuel, wep and no wind.
Time to alt
1k 13sec
2k 26
3k 40
4k 55
5k 1.10
6k 1.27
7k 1.43
8k 2.01
8k 2.19
10k 2.35
11k 2.54
12k 3.12
13k 3.30
14k 3.49
15k 4.08
16k 4.29
17k 4.50
18k 5.14
19k 5.38
20k 6.04

[juzz]

"Notice in testing against a FW190-A series the 190 out climbs the Tempest? This should not be possible."

Why not? Chart the A&AEE Tempest V climb rate with the USN Fw 190G-3 data - the German fighter does have a slightly better climb rate for most altitudes.

[niklas]

Hi again

@sable

i did some stall tests. With autotrimm climb the tempest stalls at ~101mph (i began at 120mph and reduced climb speed until the aircraft stalls).  I used a bit engine power to fly level.
Without engine power and pulling on the stick (not using autotrimm) i was even able to get IAS below 100mph.

@funked
11400lb/2430hp = 4,7 lb/hp !!

a climbrate with more than 4500ft/min is very questionable imo.
for comparison: 109G10 = 4,15 lb/hp and only 300ft/min more climbrate???
190D9 = 4,125 lb/hp and even 300ft/min less??

 

It's about as unreasonable as an 8500 lb, 1700 hp Fw 190 doing 4000 fpm like the USAAF found and like we have in AH.

this is simply not true. Without the outer guns, the current AH 190A5 climbs in 2k with 3800ft/min. In 2k the engine power of a bmw801D engine is already a bit higher compared to sealevel (where itīs impossible to measure a climbrate), so the theoretical climbrate at sealevel is even a bit less!

For this 190A5 we have a ratio of 4,91 lb/HP near sealevel, but 750ft/min less climbrate??? The ratio lb/hp is 4,5% higher, but the total climbrate (including "negative" climbrate due to drag, usually around -1000 -  -1200ft/min) is 15% worse for the 190a5??

And this, though the tempest was optimized for speed, not for climb??

@buzzbait
 

Top speed of Tempest at S.L. was 392mph on 2435 hp. As compared to the FW190D at 382mph without ETC 504. So obviously the Tempest is getting more speed per horsepower at S.L.

simple math:
tempest: 392/2435 = 0,1609
190D9: 382/2240 = 0,1705
The dora wins

niklas

[Buzzbait]

S! Niklas

You forgot the weight Niklas.  The Tempest weighs 11,400lbs, the 190D9 9450lbs.  Factor the power to weight in as well as the top speed and you see the Tempest has a more efficient airframe, generating less drag.

[Sable]

Out of curiosity I plugged the Tempest and the 190A5 into Zigrat's nifty spreadsheet, and amazingly they could produce a nearly identical sustained turn.  Punching in the Mustang, and tweaking it for it's combat flaps, it produced a slightly superior turn(about 1-1.5 deg/sec and ~100ft of radius).  If I reduced the Tempests stall speed to 98mph as tested by Niklas, and raised the HP to 2400(my data was for a 2180hp Tempest), the Tempest now outturned both of em(19.25 deg/sec or so, which is fairly close to Niklas' number of an 18 second circle).

I always find it amazing how I can put numbers into that spreadsheet and match anecdotes like AFDU turn tests, and then turn around and plug in test data from a flight sim and match them too.  

Sable
352nd FG

[funked]

F4UDOA again you have baffled me.  
I think you are mixing up the AFDU Competitive Trials (Sabre II, 2090 hp) with the A&AEE Performance measurements (Sabre IIA, 2235 hp) and the aircraft in AH (Probably Sabre IIB or Sabre V, 2400+ hp).  It's a different plane in each test.

Niklas I think it is possible that the Tempest in the A&AEE tests was making more power than the rating (due to installation effect or conservative engine rating), or it had some prop efficiency that made it perform better than your calculations would predict.  The fact is that the aircraft did produce this performance, and this was a real flight test, not a calculation like some German or American aircraft.  

And yes I screwed up the lb/hp number - bad math.  Also 4000 fpm is correct for 8500 lb, 1700 hp Fw 190.  All Pyro did was add in the weight of cowl guns/ammo to bring weight up around 8800 lb and drop climb to 3800 fpm.      <S>


[This message has been edited by funked (edited 03-21-2001).]

[flakbait]

Some fuel for this little discussion:
 http://user.tninet.se/~ytm843e/tempest.htm

Here's the numbers he gives for our Tempest Mk V:

Series number: IIB
Aircraft: Tempest V
Hp/RPM/Altitude:

2420/3850/sealevel
2045/3850/13,750 ft
1735/3700/17,000 ft

Comments:
Four barrel SU carburator two sided blower impeller. (1944)

And aircraft specs:

Wing span: 41 feet
Wing area: 302 sq/feet
Length: 33 ft 8 in
Weights: 9,000 empty; 11,400 loaded
Top speed: 435 mph @ 17,500 ft
Time to 15k: 5 minutes
Engine: Napier Sabre MkIIA/B/C
Max power: 2180 hp
Prop: 4-blade 14 foot diameter


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Flakbait
Delta 6's Flight School
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