Spit 25Lbs

[LLv34_Flanker]

S!

 

You guys seem to be unable to read a simple chart from both Spitfire performance and ww2aircraft performance. Same test, same values. The 543 was better than 165, but neither was stated to climb ridiculously high numbers. Not on MS gear or FS gear, rads open or closed. Highest attained was 5050ft/min for what, roughly 500ft. Read the chart right, even has numbers for each curve. And the estimated climb rate gain of 900-950ft was over the +18lbs vs +25lbs.  Nowhere does it state that the climb rate is over 5500ft/min. Get real already. Seems you interpret technical documents to suit your agenda not for getting correct answers. Read this: http://www.spitfireperformance.com/bs543climb.jpg Below 5000ft/min. Every frigging document states the IX, any model had climb of less than 5000ft/min.Or how about the following, JL165 again. Read and understand, do not add fantasy values or estimates.

 

Aircraft and Armament Experimental Establishment
Boscombe Down
1 Feb 1944

Spitfire IX JL.165
(Merlin 66)

Trials at +25 lb/sq.inch boost
with Rotol 4 blade propeller

SUMMARY

 

..................Performance trials and a brief assessment of handling characteristics have been completed on a standard Spitfire IX with Merlin 66 engine, adjusted for maximum boost of +25 lb/sq.inch. 150 grade fuel to Specification RDE/F/253 was used through all tests.

 

Engine conditions - 3000 rpm + 25 lb/sq.in. boost.

 

Climbs

 

Max. rate of climb in M.S. gear (radiator flaps open)	5080 ft/min up to 500 feet
Max. rate of climb in F.S. gear (radiator flaps open)	4335 ft/min at 11,400 feet
Max. rate of climb in F.S. gear (radiator flaps shut)	4750 ft/min at 11,400 feet
Estimated increase in rate of climb below full throttle heights due to increase in boost from +18 to +25 lb/sq.in.	950 ft/min

 

Level speeds

 

Maximum true air speed in M.S. gear	364 mph at 2,800 feet
Maximum true air speed in F.S. gear	389 mph at 13,800 feet
Estimated increase in speed below full throttle heights due to increase in boost from +18 to +25 lb/sq.in.	30 mph.

 

Conclusions ..................The increase in performance with the increase in boost from +18 to +25 lb/sq.in. corresponds to : 1) 950 ft/min. in rate of climb in M.S. gear 2) 900 ft/min. in rate of climb in F.S. gear 3) 30 mph in maximum level speed in M.S. and F.S. gear ..................There is also an increase in fuel consumption of approximately 24%. ..................No maintenance difficulties of the engine were experienced.

[=362nd_FS=RoflSeal]

5 minutes ago, LLv34_Flanker said:

S!

 

You guys seem to be unable to read a simple chart from both Spitfire performance and ww2aircraft performance. Same test, same values. The 543 was better than 165, but neither was stated to climb ridiculously high numbers. Not on MS gear or FS gear, rads open or closed. Highest attained was 5050ft/min for what, roughly 500ft. Read the chart right, even has numbers for each curve. And the estimated climb rate gain of 900-950ft was over the +18lbs vs +25lbs.  Nowhere does it state that the climb rate is over 5500ft/min. Get real already. Seems you interpret technical documents to suit your agenda not for getting correct answers. Read this: http://www.spitfireperformance.com/bs543climb.jpg Below 5000ft/min. Every frigging document states the IX, any model had climb of less than 5000ft/min.Or how about the following, JL165 again. Read and understand, do not add fantasy values or estimates.

 

 

It seems you are the one who can't read m80,

how about read what I posted again.

Also this are Spitfires on 18lbs boost.

Edited October 9, 2019 by =362nd_FS=RoflSeal

[LLv34_Flanker]

S!

 

 I posted the final test values of the supposed mega climber JL165, from Boscombe Down 1944. You make up values that were not even there, on that document. Highest official value for it was 5080ft/min up to 500ft. Not your "let me make up a fantasy value of 5500ft/min". The values are stated as improvement using +25lbs instead of +18lbs. Or do you add the summary as well to it?

[=362nd_FS=RoflSeal]

16 minutes ago, LLv34_Flanker said:

S!

 

 I posted the final test values of the supposed mega climber JL165, from Boscombe Down 1944. You make up values that were not even there, on that document. Highest official value for it was 5080ft/min up to 500ft. Not your "let me make up a fantasy value of 5500ft/min". The values are stated as improvement using +25lbs instead of +18lbs. Or do you add the summary as well to it?

The climb in the first stage supercharger was done with radiators open only

The climb in the second stage was done with both testing radiators open and closed with the difference being just over 400ft, hence the climb on JL165 as tested by A&AEE, if they did a run with closed radiators would have been ~5500ft.

As A&AEE concludes, they are in fair agreement with previous testing done with the same exact airframe.

The report also goes further saying the Spitfire Mk IX JL.165 is noted to be a bit of a dog compared to other Spitfires and it compares it to BS.543

Which at 18lbs has 500fpm higher climb rate at the first supercharger gear. Hence it is reasonable to suggest a better conditioned Spitfire akin to BS.543 would have better performance with 25lbs of boost then what JL.165 has.

BS.543 with 150 Octane fuel would do 5600 fpm with radiators open. (+900 fpm thanks to 25lbs boost)
With radiators closed it would go to 6000 fpm if the radiators were closed (+400 fpm)

 

My reading skills aren't what's wrong, you should look to improve those instead.

Edited October 9, 2019 by =362nd_FS=RoflSeal

[LLv34_Flanker]

S!

 

Read the report regarding JL165 from 1.4.1944 at Boscombe down, which is the latest test on JL165. No 5500ft/min. You pick parts that suit your agenda. I scoured thru all those tests there. I took the latest official report. And again 

 

When you look thru all the IX tests the average is exactly what I have been saying all the time, around 4700ft/min. 

Edited October 9, 2019 by LLv34_Flanker

[=362nd_FS=RoflSeal]

4 minutes ago, LLv34_Flanker said:

S!

 

Read the report regarding JL165 from 1.4.1944 at Boscombe down, which is the latest test on JL165. No 5500ft/min. You pick parts that suit your agenda. I scoured thru all those tests there. I took the latest official report. And again 

jeez, it's like speaking to wall.

1 - Read what lines 2 and 3 stand for.

2 - Calculate the difference between lines 2 and 3.
3 - Now add that difference to line 1

Edited October 9, 2019 by =362nd_FS=RoflSeal

[PainGod85]

Just now, LLv34_Flanker said:

S!

 

Read the report regarding JL165 from 1.4.1944 at Boscombe down, which is the latest test on JL165. No 5500ft/min. You pick parts that suit your agenda. I scoured thru all those tests there. I took the latest official report. And again 

 

MS gear with radiator flaps open. Thank you for disproving the point you were trying to make.

 

Again, this airframe was tested by Rolls-Royce with radiators closed. During this test, the figures in climb were unsurprisingly in excess of the ones obtained in this later test by A&AEE, where the radiator flaps were open during tests in MS gear.

[LLv34_Flanker]

S!

 

 Damn you are thick headed. 2 stands for FS gear with radiator Open, 3 stands for Closed. You do not add this value to the MS gear aka 1. It is clearly written in the test values of different gears FS and MS. They do not add. And if you read the damn graph it is easy to see that MS gear is worse in climb at 3kft and 6kft respectively.

Edited October 9, 2019 by LLv34_Flanker

[=362nd_FS=RoflSeal]

4 minutes ago, LLv34_Flanker said:

S!

 

 Damn you are thick headed. 2 stands for FS gear with radiator Open, 3 stands for Closed. You do not add this value to the MS gear aka 1. It is clearly written in the test values of different gears FS and MS. They do not add.

The difference in climb rates due to the difference in drag do add. Both climbs are at the same speed (170 mph IAS).

And again

Vickers got 5600 fpm in MS gear with radiators closed.
Rolls Royce got 5700 fpm in MS gear with radiators closed.

All 3 tests runs used the same aircraft (JL.165)

You say

Quote

 I scoured thru all those tests there. 

But you clearly didn't look hard enough, especially when I posted it in this thread.

Not only you can't read.

You should see a doctor or you are evidently selectively blind

Edited October 9, 2019 by =362nd_FS=RoflSeal

[PainGod85]

Just now, LLv34_Flanker said:

S!

 

 Damn you are thick headed. 2 stands for FS gear with radiator Open, 3 stands for Closed. You do not add this value to the MS gear aka 1. It is clearly written in the test values of different gears FS and MS. They do not add.

 

You still don't get it. For climb speeds at a constant CAS, it is absolutely possible to correct for radiator drag by using numbers for a different gear.

 

1. We know the drag from FS with compared to FW without radiators open cost the plane around 500 fpm in Vz.
2. We know the plane's climb speed in MS gear with radiators open.
3. We know CAS in every case was the same.
4. Thus we may extrapolate MS climb speed with radiators closed to be the speed given in the MS climb speed test plus the difference between the two climb tests done in FS gear.

[LLv34_Flanker]

S!

 

 You still do not get it do you? Look at the MS gear graph. Maximum climb is up to a "whopping" 500ft aka 166m. At 3000ft the FS gear with radiator closed surpasses the MS gear and with radiator open at 6000ft. After that MS gear is worse than FS at all altitudes.

[=362nd_FS=RoflSeal]

7 minutes ago, LLv34_Flanker said:

S!

 

 You still do not get it do you? Look at the MS gear graph. Maximum climb is up to a "whopping" 500ft aka 166m. At 3000ft the FS gear with radiator closed surpasses the MS gear and with radiator open at 6000ft. After that MS gear is worse than FS at all altitudes.

Now you are trying to change the argument? What has the critical altitude got to do with maximum climbrate possible

Reminder, this was supposedly your beef
 

Quote

I dare you to present any data that says a Spitfire +25lbs climbed over 30m/s or even 27m/s. 

Which you have been utterly BTFO on.

Not only have I presented data that the Spitfire Mk IX could climb easily over 27m/s. I presented estimations that a better conditioned aircraft similar to BS.543 would climb over 30m/s, based on A&AEE data.

Edited October 9, 2019 by =362nd_FS=RoflSeal

[PainGod85]

Just now, =362nd_FS=RoflSeal said:

Now you are trying to change the argument? What has the critical altitude got to do with maximum climbrate possible

Reminder, this was supposedly your beef
 

Which you have been utterly BTFO on.

 

Never concede defeat when you could just move the goalpost. - Arguing in bad faith 101

[LLv34_Flanker]

S!

 

 Because the RoC is exactly what is shown in those 3 lines. MS gear gives you a better climb at SL and a bit up, exactly as shown by the chart. Lets make an example. MS gear / radiator open vs FS gear / radiator open, 12000ft altitude. MS gear RoC is there ~3100ft/min. For FS gear it is ~4200ft/min. MS loses. Now if we look at 500ft as the peak of MS rad open vs FS rad open it is 5080ft/min vs 4200ft/min. MS wins this time. So how do I read the chart wrong? There is no "estimated increase" anywhere on that chart. For FS the difference is stated, 435ft/min increase with rads closed.

Edited October 9, 2019 by LLv34_Flanker

[=362nd_FS=RoflSeal]

3 minutes ago, LLv34_Flanker said:

S!

 

 Because the RoC is exactly what is shown in those 3 lines. MS gear gives you a better climb at SL and a bit up, exactly as shown by the chart. Lets make an example. MS gear / radiator open vs FS gear / radiator open, 12000ft altitude. MS gear RoC is there ~3100ft/min. For FS gear it is ~4200ft/min. MS loses. Now if we look at 500ft as the peak of MS rad open vs FS rad open it is 5080ft/min vs 4780ft/min. MS wins this time. So how do I read the chart wrong? 

I see you couldn't even follow my basic instructions to get a basic estimation for a MS climb with closed radiators 

Edited October 9, 2019 by =362nd_FS=RoflSeal

[PainGod85]

Alright, let's try this a different way.

1. You have a crane with two different engines that can be used to drive it. One engine is stronger than the other, running at higher RPM.
2. Now you have two weights, of which one is substantially heavier than the other.
3. You test the weaker engine with both weights, noting that the heavier weight takes longer to be lifted ten meters.
4. You test the stronger engine, but only with the heavy weight.
5. You calculate expected performance of the stronger engine by correlating the difference in speed of the weaker engine and adding it on top of the measured value obtained on the stronger engine with the heavy weight.

[Matt]

Fwiw, did another quick test. If i use this as reference and assume this is for 170 mph CAS (i've not actually checked, but that number has been posted here), open radiator flaps and gear switch at 6000 ft.

 

I get this (took the times from the graph, so some times might be off by a bit, but atleast the total time is clearly 9 minutes for 30000 ft).

 

So it does climb a bit too fast, with radiator flaps open, compared to that source. I'm always having trouble getting a good, reliable and reproducable climb rate at sea level (and considering the source gives peak climb rate for less than 1000 ft climb i wouldn't bother comparing it) but even when i disregard climb time at low altitude (biggest room of error), it's still too fast. Especially because when engaging second gear, the climb rate jumps to roughly 5000 ft/min. I think performance in second gear is the real issue. Not the climb rate for a couple of seconds at sea-level.

Edit: But it seems like this test report is from a poorly running Spitfire with 25lb, since it's possible to find tests with similar performance on 18lb and better performance (very close to the current ingame performance) with 25lb.

 

Track.

Spitfire 25lb climb.zip

Edited October 10, 2019 by Matt

[CUJO_1970]

21 hours ago, PainGod85 said:

But why care about portraying facts accurately when they might as well be distorted to fit your narrative, right?

 

Here's a narrative for you: go test using _historical methods_ (don't forget gear change) and see what several of us already know - the Spit is climbing well faster than historical tests show.

 

Then report back before you run your mouth off any more about accusing anyone of distortions and narratives.

[Kurfurst]

Clearly there is an issue with the  climb rate worth further testing and investigation, yet clearly some would very much like if it would be remain in this state.

 

However apart from the the absolute rates of climb measured, which can be perhaps explained, at least partially with differing test methods, load, and atmospheric conditions, to me it seems that there is a far more serious issue with the altitude range that this climb rate is kept up.

 

That is to say, the in game spit managed to maintain the climb rates that are already suspected to be to high to begin with to far higher altitudes than it was historically capable of. The JL 165 tests indicate the climb rate fell off rapidly from about 11 000 - 11 400 feet, or about 3500 meters. This is logical because that is the maximum altitude the Merlin 66 can maintain 25 lbs boost in climb, as a result, if you went higher, boost and power fell, and so did climb.

 

Though I need some testing to do myself to confirm, testing by others seem to indicate that the in game 25 lbs Spit’s climb not only does not rapidly decrease from 11k feet (up to that altitude it should be pretty impressive) as it should but it even increases / remains the same up to 6000 meters and only then starts to fall back.

 

The center of the issue is the ridiculous climb rate observed above 3500m.

Edited October 9, 2019 by VO101Kurfurst

[JtD]

10 hours ago, Matt said:

So it does climb a bit too fast, with radiator flaps open, compared to that source.

 

Thanks for doing that test, now I don't have to do it. Please keep in mind that the climb performance tested at 18lb boost on BS543 gave a time to 30k feet of 8.4 minutes - faster than JL165 by more than a minute at 18lb and still faster than JL165 at 25lb. Another Spitfire IX not closer described climbed from 1k to 30k in 8.3 minutes at 12lb boost.

 

Also interesting is testing with the Spitfire VIII, which is pretty similar to a IX, but a bit heavier. 8.6 minutes to 30k. A comparison test 18lb to 25lb boost boosted climb in FS gear from around 4000 fpm to around 5000fpm, MS down low was 4600fpm to 5600fpm at sea level, so a 1000fpm gain.

 

All these figures indicate, and that's also what the British state, that JL165 is not the best performing example, and may not be representative for a Spitfire IX in perfect condition which is supposed to be modelled in game.

 

When we did the FM for the Il-2:1946 Spitfire IX we had our difficulties when we took the properly modelled 18lb and simply added the 400hp the extra boost gives. It didn't add up, also because JL165 was performing sub par. If you go with 3800fpm rads open as done on BS543 and add the extra 900-1000fpm as found in various tests for 4700-4800fpm, you're probably more realistic if you want to model a Spitfire IX in ideal condition than if you go with the 3400/4300fpm of JL165.

 

The extra 400fpm would reduce time to 30k altitude from 540s to 482s. It therefore appears the guys in Moscow arrived at the same conclusions we did back then. I think it's the best compromise possible (if you want to model aircraft without production faults).

[Matt]

Yes i see now that this JL165 test seems to show a surprisingly low performance compared to other 25lb test and even 18lb tests. Not sure why that test was brought up here in the first place, when you can find 18lb tests with similar performance. I guess it was only meant to claim that sea level climb rate is too high, which i still consider to be impossible to test and compare accurately anyway.

 

Overall climb rate seems to fine.

[Holtzauge]

At full fuel load I get sea level climb rates of 23.3 m/s for G14 at 1.7 ata and 27.7 m/s for Mk9 at +25 boost in the C++ simulation. At 50% fuel it goes up to 25.0 m/s and 29.9 m/s respectively. So to me Il-2 seems a bit optimistic but I can't see that the Mk9 stands out in any way. However, as I recall it this has always been the case with Il-2 but on the positive side most planes have higher than historical rates so the important issue of the relative performance is maintained to some extent anyway (Maybe with the exception of the G14 sea level climb rate which at 27.5 m/s looks rather optimistic).