Author Topic: Let´s talk about the tempest (Read 2589 times)

niklas · « **on:** March 19, 2001, 03:12:00 PM »

Hi

I made some strange experiences with the tempest. It seems to hold E very well.

I began to compare some sources to AH.

From the AFDU test:
"It [Tempest V]is fitted with a Napier Sabre II engine of approximately 2090 h.p. (same as Typhoon IB)!"

This is important to me, because the current climbrate in AH is impossible a 2090HP engine. With -1050ft/min sinkrate (without propdrag, pure drag), full power let the Tempest climb with 4550+1050=5600ft/min. With a full weight of 11400lb, this means ~2470HP (assuming a prop efficiency of 0,8).

I know that some Sabre engines produced more than 2400HP. My book lists the Sabre IIB engine with 2435HP, but this with 4000rpm and a boost of 1,97bar.

1,97bar is ~28psi. I always wondered myself why engish boost instruments have negative numbers. Is it possible that 0 boost means 1bar, 1 atmosphere? If so, then the engine had a boost of +14 for 2430HP.
The current AH Tempest shows 3700rpm @ +9psi, and this should be only 2050hp, right (or maybe 2150?) ?

2430HP- i mean, this was maybe used to chase V1 rockets, sacrificing lifetime of the engine, but for usual combat aircrafts?? All sources i´ve seen so far speak from 2050-2150HP engines.

AFDU test compares tempest to typhoon (same engine 2090hp)
", the maximum speeds of the Tempest at all heights are 15-20 mph faster"
This is exactly what is modelled in AH, but this refers to the same engine. So, what now? With 2430HP the tempest should be a lot faster. With 2090HP it is modelled correctly but climbrate is far too good.

"The Tempest climbs at a slightly steeper angle and at the same airspeed producing 200-300 ft. increase in maximum rate of climb. "

Even with the increase in simulated power, 4550ft/min compared to 3500ft/min of the typhoon doesn´t sound right. I mean a fw190D climbs with 2240Hp 4250ft/min. A Tempest is 2000lb heavier, has only 200hp more and climbs with 4550 ft/min at sealevel?

comparision with mustang III
"Turning Circle
28. The Tempest is not quite as good as the Mustang III. "

the tempest in AH outturns the mustang.
100% fuel:
P51 (4*´50, flaps 1 notch down): 21sec
Tempest : 18,5 sec

25% fuel
P51 (") : 19 sec
Tempest : 16,5 sec

AFDU Turn compared to Fw190:
"There is very little difference in turning circles between the two aircraft"
hmm i think no AH test needed here

I´m very surpised that the AH-tempest turns so good. I mean it had a modified (laminar?) wing compared to the typhoon, and the AFDU report speaks from "much thinner wings" compared to the typhoon. Both should be a disadvantage in a turnfight.

It was optimized for speed not for manoevering. It turns imo way too good.

opinions?

niklas

[This message has been edited by niklas (edited 03-19-2001).]

Graywolf · « **Reply #1 on:** March 19, 2001, 03:37:00 PM »

Quote

Originally posted by niklas:

comparision with mustang III
"Turning Circle
28. The Tempest is not quite as good as the Mustang III. "

the tempest in AH outturns the mustang.
100% fuel:
P51 (4*´50, flaps 1 notch down): 21sec
Tempest : 18,5 sec

25% fuel
P51 (") : 19 sec
Tempest : 16,5 sec

I'm not saying wether you're right or wrong, but Turning [B}Circle[/B] which you say the report measured and Turn Rate which is what the Aces High figures you quote are for are not the same thing.

------------------
Graywolfe <tim@flibble.org>

Karnak · « **Reply #2 on:** March 19, 2001, 04:13:00 PM »

niklas,
AH has a later Tempest MkV with the 2300+hp engine.

------------------
We few, we happy few, we band of brothers;
For he to-day that sheds his blood with me
Shall be my brother

Bring the Spitfire F.MkXIVc to Aces High!!!

Sisu
-Karnak

niklas · « **Reply #3 on:** March 20, 2001, 03:10:00 AM »

Graywolf, the speed and G-load in a sustained turn in AH is:
P51: 160mph@2,3G
Tempest: 175mph@2,9G

Turnradius:
P51: 820ft
Tempest: 765ft

The Tempest outturns the P51 and also flies a smaller radius!

And the Tempest keeps the speed in a turn, incredible!

btw, did a 2430HP Sabre engine need 150oct?

niklas

Buzzbait · « **Reply #4 on:** March 20, 2001, 04:50:00 AM »

S! Niklas

I would suggest you do some more research on the Tempest. The standard Napier Sabre IIa engine had 2180 hp. This is what equipped the early Typhoons. The later model Typhoons and Tempests had the Sabre IIb with 2435hp.

This figure of 2090 hp is from where? I would say this perhaps refers to hp at a particular altitude, not Takeoff. Never have I seen 2090 given as a figure for the Sabre IIb.

Also, which P-51 model did you use for testing? The "Mustang III" was the British name for the P-51b. In addition, the British did not test the Mustang III with the rear fuselage 85 gallon tank full.

The Tempest DID have laminar flow airfoils. Which gave it far less drag than the Typhoon, and thereby improved its initial and zoom climb rate considerably, as well as the sustained climb. 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.

The weight of the Tempest Fighter, (the model in AH) was 11,400 lbs loaded.

Finally, the Napier Sabre engines operated under far less boost during emergency power applications than for example the Merlin Spitfire engines or the Jumo that powered the FW190D. The Napier Sabre engine was a relatively new design (by WWII engine standards) and was still being developed. It had a capacity of 36.65 litres from 24 cylinders in an H pattern, and a peak rpm of approx. 3800 as compared to the Jumo 213 which was a 12 cylinder inverted V with a capacity of 35 litres and a peak rpm of 3250. The Sabre engine got its power from rpm, the Jumo from boost. The Sabre IIb only went from +8 boost normal boost to +10 boost on emergency power.

What this meant, was the difference between normal Combat rating and Emergency power rating on the Sabre was much less proportionately than with the Jumo. The base power level of the Sabre was higher.

Finally, the 190 model which was compared to the Tempest for turnrate was a 190 A4, (PE882 if I remember correctly, you can find the exact serial numbers in "The Captive Luftwaffe", which details all the various German aircraft captured and used by the British AIR FIGHTING DEVELOPMENT UNIT) which was a good 1000lbs lighter than the 190D, with the same wing area.

Buzzbait · « **Reply #5 on:** March 20, 2001, 05:04:00 AM »

S!

By the way, the same test you are referring to also shows the Tempest turns a little worse than the Typhoon. (fighter model of the Typhoon, weight 11,600) which would indicate that the Tempest did suffer a little from the effects of the laminar flow wing. Of course those are sustained turn rates, and the Tempest was best flown at high speed, in a manner similar to the P-51.

funked · « **Reply #6 on:** March 20, 2001, 06:45:00 AM »

Yes RAF manifold pressure gauges read "PSIG", that is lb/ft^2 gauge pressure. So at sea level 0 PSIG is 1 atm.

The reason that the AFDU Tempest trial numbers don't make sense when you compare with Aces High is because AH is using one of the later engines with 2400+ hp, probably Sabre IIB or Sabre V, and it looks like all the trials were done with an earlier mark of Sabre, using only Normal Power, not WEP.

Here is a chart I made to show the different Sabre powerplants used in Tempest and Typhoon aircraft:

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

Vermillion · « **Reply #7 on:** March 20, 2001, 06:49:00 AM »

Is this the data your referring too Niklas?
http://users.supernet.com/lecc/tp.html

Either way its some good Tempest Info for those that are interested. This link was posted over on AGW last week or so.

------------------
Vermillion
**MOL**, Men of Leisure

F4UDOA · « **Reply #8 on:** March 20, 2001, 07:59:00 AM »

Heya Verm,

Did you notice the climb times in that chart?

even with an initial climb of 4,300Ft, it climb to 20K is listed at 6.55Min. Not really earth chatering considering the jump start. Have have often wpndered about the data in those climb charts when I see incredible climb rates charted with mediocre climb times. For instance the F4U-1D had a combat climb to 20K in a little over 7min. So the meager climbing -1D reached 20k less than a minute behind the Rocket ship Tempest? It doesn't make sense.

Normal climb rating Combat rating
Max rate of climb in
M.S. gear 3815 ft/min @ 3500 ft FTH 4380 ft/min @ sea level
Max. rate of climb in
F.S. gear 2680 ft/min @ 15800 ft FTH 3000 ft/min @ 13500 ft. FTH
S/c gear changed when boost
in M.S. gear was +2.9 lb/sq. in. +4 lb/sq.in.
Time to 10,000 ft. 2.9 mins. 2.8 mins.
Time to 20,000 ft. 6.85 mins. 6.55 mins.
Time to 30,000 ft. 14.3 14.0

funked · « **Reply #9 on:** March 20, 2001, 08:25:00 AM »

It makes perfect sense DOA. Look at the Rate of Climb column. It rapidly drops off to 3000 fpm. And then at 5 minutes into the test, the engine is switched back to normal power (+7 boost) from maximum power (+9 boost), and the ROC drops below 2500 fpm!

The Sabre had only a single-stage two-speed supercharger and was optimized for low levels. So power dropped off really quickly above the first full throttle height. Then when the high speed (FS) supercharger gear was engaged, there was another power increase, but power rapidly dropped off again.

The F4U had a two-stage, two-speed supercharger. So climb rate did not drop off as severely.

Tempest had a huge advantage in narrow altitude ranges, but F4U didn't have so many "peaks and valleys".

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

funked · « **Reply #10 on:** March 20, 2001, 08:40:00 AM »

Another thing: From looking at some other planes (Fw 190, Spitfire), it is clear that the AH manifold pressure reading does not always correspond to the real aircraft's manifold pressure, at maximum power at a given altitude. I doubt the Tempest is an exception.

Voss · « **Reply #11 on:** March 20, 2001, 10:22:00 AM »

After running into Vulcan in the Tempest I have been flying this aircraft offline and in the TA. This airplane is superior to everything, and I don't believe it was this good in RL. I fear nothing when flying this plane! Since it is the fastest plane, you just run until your opponent is coalt, then regrab in a low g pull to a vertical climb. Nothing can follow, and if they try, you just go over the top and kill them.

This can't be right, or the U.S. would have produced this aircraft by the millions!

Defang this thing, HT or at least have another look at the numbers. Something's wrong.

------------------
Voss
13th TAS

juzz · « **Reply #12 on:** March 20, 2001, 10:31:00 AM »

Hmmm, and the Centaurus-powered Tempest II was even better.

fd ski · « **Reply #13 on:** March 20, 2001, 11:04:00 AM »

Quote

Originally posted by Voss:
After running into Vulcan in the Tempest I have been flying this aircraft offline and in the TA. This airplane is superior to everything, and I don't believe it was this good in RL. I fear nothing when flying this plane! Since it is the fastest plane, you just run until your opponent is coalt, then regrab in a low g pull to a vertical climb. Nothing can follow, and if they try, you just go over the top and kill them.

This can't be right, or the U.S. would have produced this aircraft by the millions!

Defang this thing, HT or at least have another look at the numbers. Something's wrong.

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

Looks what would have happened to that pony of your without that british engine

------------------
Bartlomiej Rajewski
aka. Wing Commander fd-ski
Northolt Wing
1st Polish Fighter Wing
303 (Polish) Squadron "Kosciuszko" RAF
308 (Polish) Squadron "City of Cracow" RAF
315 (Polish) Squadron "City of Deblin" RAF

Turning 109s and 190s into scrap metal since 1998

Northolt Wing Headquarters

funked · « **Reply #14 on:** March 20, 2001, 11:36:00 AM »

LOL Voss good one!