Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: niklas on March 19, 2001, 03:12:00 PM
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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 iīve 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 doesnīt 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*ī50, 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 (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Iīm 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).]
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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*ī50, 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.
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Graywolfe <tim@flibble.org>
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niklas,
AH has a later Tempest MkV with the 2300+hp engine.
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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
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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
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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.
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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.
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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:
(http://www.raf303.org/funked/napier.gif)
[This message has been edited by funked (edited 03-20-2001).]
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Is this the data your referring too Niklas?
http://users.supernet.com/lecc/tp.html (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.
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Vermillion
**MOL**, Men of Leisure
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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
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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).]
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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. (http://bbs.hitechcreations.com/smf/Smileys/default/frown.gif)
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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.
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Voss
13th TAS
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Hmmm, and the Centaurus-powered Tempest II was even better. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
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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 ? (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Looks what would have happened to that pony of your without that british engine (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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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 (http://www.raf303.org/northolt/)
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LOL Voss good one!
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FdSki wrote:
Heheheh can't live with the fact that US planes weren't the best ?
Blah blah... blah blah blah (http://bbs.hitechcreations.com/smf/Smileys/default/tongue.gif)
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. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
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Vermillion
**MOL**, Men of Leisure
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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
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@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 (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif) (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 (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif) )
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 (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif) (initial climbrates from flight tests are often excellent, maybe theyīre the result of a little zoom climb at the beginning?? )
niklas
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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. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
[This message has been edited by funked (edited 03-20-2001).]
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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.
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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.
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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 (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif). 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.
(http://www.hitechcreations.com/images/charts/tempestclimb.gif)
Notice the F4U reaches gives up over 1K per minute for almost 10K
(http://www.hitechcreations.com/images/charts/f4u1dclimb.gif)
I wonder if someone has tested the Tempest in AH time to 20K??
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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.
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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
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"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.
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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
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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.
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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. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Sable
352nd FG
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F4UDOA again you have baffled me. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif) <S>
[This message has been edited by funked (edited 03-21-2001).]
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Some fuel for this little discussion:
http://user.tninet.se/~ytm843e/tempest.htm (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 (http://www.worldaccessnet.com/~delta6)
Put the P-61B in Aces High
Whattaya mean I can't kill em? Why the hell not?!
(http://www.worldaccessnet.com/~delta6/htbin/behappy.jpg)
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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.
were can i find this sheet and how to get turn speed (degree/sec) and radius (ft.) outta it??
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S!
Buzzbait, weight plays only a minor role when you look at the topspeed. But the theoretical CD0 of the tempest is very low (~0,014). Of course all aircrafts with large wingareas have naturally a lower CD0 compared to fighter with higher wingloading.
Sable is it possible to have a turnrate in Zigrats sheet when you enter "1G" ?? If so than thereīs a little bug in it.
What does the climbrate of Zigrats sheet say about the tempest? I got for my sheet 4050ft/min for the dora (very close to the FW-data), but only 3700ft/min for the tempest...(2430hp)
@funked
i didnīt make some real calculations so far, i basically compared the performance claims to the performances of other fighters. And when several different sources / stories / tests show that the tempest wasnīs a really good turnfighter, and it performs here completly different, then something has to be fixed, right?
niklas
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Well the AFDU turn comparisons are for a plane with Sabre II and only 2090 hp. Wouldn't the extra 300 hp help a bit? And how do we know that the AH Tempest does not have a Sabre V? Then you are looking at 500 hp more than the AFDU test and 200 hp more than the A&AEE figures. Which actually makes sense, because low level speed and climb in AH are in excess of the A&AEE figures. 500 hp would probably help the turn rate a whole bunch. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Also AFDU appears to consider only turn radius, not turn rate.
Another factor - early Tempest V had the same long Mk. II cannon with barrel fairings as the Typhoon. AH has the Mk. V cannon completely inside the wing. Maybe AFDU tested one with the Mk. II cannon, which would have affected CL and CD of the wing? http://user.tninet.se/~ytm843e/cannons.htm (http://user.tninet.se/~ytm843e/cannons.htm)
Yet another factor - in any comparisons with the Typhoon, remember that the Tempest has a 4-bladed prop vs. 3-blades on the Typhoon. So it seems maybe the Tempest would able to get more thrust at low speeds than the Typhoon, even with the same engine.
I don't know the answers, but these are all real factors that have to be considered.
[This message has been edited by funked (edited 03-21-2001).]
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Dora vs Tempest is very fun fight. Pilot quality is the main factor here.
Even Pierre Closterman (sp) can say something about that, right ? (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
Fighting a Tempest really adds a challenge to the Dora. Other planes don't come close.
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Air intake efficiency was measured on JN.731 by the A.& A.E.E. Here's a brief summary of the results:
Measurments of air intake efficiency under various conditions of climbing and level flight have been made on Tempest JN.731.
Intake efficiency %
Climb at combat power Radiator flap open
Vi mph....8000 ft. ....19000 ft. .... 28500 ft.
140 ....... - .......... 162 .......... 135
160 ...... 178 ......... 151 .......... 129
180 ...... 159 ......... 142 .......... 124
200 ...... 148 ......... 134 ........... -
220 ...... 139 ......... 131 ........... -
240 ...... 133 .......... - ............ -
Level flight Radiator flap closed
Vi mph .... 8000 ft
180 ....... 123
220 ....... 118
260 ....... 116
300 ....... 116
340 ....... 116
380 ....... 116
Examination of the results obtained will disclose some rather unusual features, the most striking of which are :-
i. The efficiencies obtained are surprisingly high.
ii. The efficiencies when plotted against Vi do not lie on the same curve at all heights but vary with height.
iii. Despite ii. the rams plotted against true airspeed appear to lie on one curve at all heights (for a given flight condition, such as climb).
Conclusions:
The air intake system of the Tempest V is very good, and the efficiencies, expressed relative to the forward speed of the aircraft, exceeded 100% by varying but appreciable amounts.
This fact is due not only to good design of the intake itself but also to the positioning of the entry to the intake which is such that full advantage is taken of the slipstream from the propeller.
Both Tempests used in the AFDU and AAEE were production aircraft of the JN series from the first batch of 100 built.
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Tempest Performance Testing (http://users.supernet.com/lecc/tp.html)
Spitfire Performance Testing (http://www.fourthfightergroup.com/eagles/spittest.html)
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my spreadsheet is only about 90% accurate
i recently got a new book and it has some prop efficiency curves (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
so i should be able to make it more accurate, but it will still be difficult to include factors in the spreadsheet such as different wing efficiencies since all planes are different.
but i can probably get the accurac up to 95%
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Well, I realise it isn't perfect, but it definitly makes a nifty tool for "napkin" type calculations. Honestly, I don't think it's too far off from what the flight models in WB or AH are doing.
As for measuring a turn rate with it, the trick is to increase the G until you can find the lowest speed where T-D =~ 0. This will give you the best theoretical sustained turn speed.
Ignoring that stuff though, I would still be worried if a fully loaded Tempest were stalling at about 10 mph below the "book" number for it.
Sable
352nd FG
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Well the AFDU turn comparisons are for a plane with Sabre II and only 2090 hp. Wouldn't the extra 300 hp help a bit? And how do we know that the AH Tempest does not have a Sabre V?
Unfortunatley they didnīt mention whether they used always normal power setting ( 2090hp)or whether they switched for several tests to combat power.
I think youīre right with the Sabre V engine. It really looks like that our AH Tempest has the 2600hp Sabre V engine. This would explain the huge difference in climbrate between the Tempest and Typhoon , 1k/min, (though the climbrate is imo still too good), and the rated altitudes are very smiliar to the Sabre V of your engine chart.
btw our typhoon has also a 4-bladed propeller
niklas
[This message has been edited by niklas (edited 03-21-2001).]
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Juzz,
Where have you seen a FW190G-3 tested by the USN? I have test data of the FW190A-5.
Funked, maybe I'm missing engine specs. But the sustained climb rates vrs sustained climb time IMHO do not seem to correspond.
For instance the sustained climb of the NIK2 appears to be similar if not a little worse that the Tempest. However the climb time to 20K I believe is a little better. But when compared in average rate of climb the Tempest should be superior.
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BTW Gents,
The low drag of the Tempest is measured at level flight. With a laminer wing that drag increases at a higher rate at high AOA than a conventional higher lift wing. This is the draw back of a laminer flow wing.
So when your pulling through your turns in a P-51 or Tempest at high AOA your wing design may not be at it's most efficient state.