Author Topic: Draining E in turns (Read 12194 times)

Angus · « **Reply #165 on:** September 05, 2004, 04:19:51 PM »

Hell Crumpp, I have to give it to you, you do an honest work of calculations.

I am collecting a database (anecdotal, image and text) of WW2 aircraft performance and events. Mail me if there is something I can help you with

(Anecdotal is my best field, I have some goodies coming)

But there are so many gaps to fill in, and if you want to have a go at it, I'll be as good a help as I can, collecting various performance data and putting into excel for instance.
That sheet I sent you actually answered many questions about the true performance of the aircraft that were put into it in the beginning, although it's just a simple document.

Calculations and data will at least slow down the flames I hope....

(As much as I like them

)

Nashwan · « **Reply #166 on:** September 05, 2004, 05:23:36 PM »

Quote

Why the JL165, it performed way below average?

It's the best and most complete data I have on the Spitfire Merlin 66 (+25).

JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate.

Here's a graph of what they estimated for Jl 165 at 18 lbs, along with other Spit VIIIs/IXs with Merlin 66:

JL 165 is in red.

If you use JL 165, you aren't going to get representitive figures for the Spit.

I've just skimmed this thread, so there might be an obvious reason, but why do you need figures for a Spit at 25 lbs?

Won't figures for a Spit at 18 lbs do?

Quote

he S.U. pump data is with a Merlin 66 (+18) and only "estimates" the speed increase. Additionally the speed increase is an average and would not hold true for all altitudes. This can be seen in the increase at full throttle height of a Merlin 66 (+18) is not nearly as large as the "average" with the fuel pump.

I don't understand why you keep referring to the SU fuel pump. This was simply a different carb, and had little effect on speed. You can see from the chart above, the yellow line is for MA 648 with an injection pump at 18 lbs, the other aircraft are all at 18 lbs, without the injection pump.

The injection pump increased full throttle height, which of course increased speed at that height as well.

At lower altitudes, there's almost no difference between the injection pump and the normal carb.

Nashwan · « **Reply #167 on:** September 05, 2004, 05:40:11 PM »

Quote

Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1

Step B - performance #s at a known altitude

Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90

I should probably re read this thread from the begining, but what does this data apply to?

JL 165, slow as it was, still did 362 mph at 4500 ft at 25 lbs.

Angus · « **Reply #168 on:** September 05, 2004, 07:25:58 PM »

Hey Nash, email me at burns@isholf.is and I'll reply with the attached XLS sheet for calculation of lift. Same goes with Gripen of course, or just anybody

Crumpp · « **Reply #169 on:** September 05, 2004, 07:33:20 PM »

I will recheck the data Nashwan. Thanks for posting the comparision.

Angus thank you for the vote of confidence. If their is anything you can use for you project or I can help you with let me know. You have my email.

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I should probably re read this thread from the begining, but what does this data apply to?

It is the know data for the A/C.

This refers to the Spitfire listed on this site:

http://www.fourthfightergroup.com/eagles/jl165.html

http://www.fourthfightergroup.com/eagles/jl165speed.gif

Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1

Step B - performance #s at a known altitude

Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 350
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90

Your correct Nashwan. I misread the chart and will recalculate.

Crumpp

Crumpp · « **Reply #170 on:** September 05, 2004, 07:46:57 PM »

I recalculated the figures for Nashwan and here are the results.

The FW-190 is at 1.42ata @ 2700U/min as my horsepower data is much more accurate for 4500 feet. All data is calculated at 356mph the max level speed of the FW-190A8 at that altitude and power setting. This forms the base information at which the performance at lower speeds can be assessed.

FW-190A8 (data is the same)
Wing area S (sq. feet) - 196.98
Airplane weight, lbs (as tested) - 9418
Wing span, ft - 34.45

Step B - performance #s at a known altitude


Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 356
Engine Horsepower (bhp at test alt) - 1730
Stall speed (mph, at test alt) - 110

speed (mph TAS) @ 4500 feet ASL
300

CL
0.229178

D(p)
952.5006

D(i)
132.1558

CL^2
0.052523

CD(tot)
0.026394

Drag (tot)
1084.6564

thrust (lb)
1667.946

excess power (bhp)
583.2895

P.E.
0.78153

Spitfire Mk IX Merlin 66 (+25) - This data represents full throttle height for the Spitfire and an easy point to calculate from. Since my data is much more complete for the FW-190 it is easier to identify the Spitfire's knowns and then establish the FW-190's performance at the same altitude. Initial data was calculated under the following known conditions:

Step A - Enter Aircraft dimension Data
Wing area S (sq. feet) - 242
Airplane weight, lbs (as tested) - 7400
Wing span, ft - 36.1

Step B - performance #s at a known altitude

Altitude (feet) - 4500
Maximum speed (at test alt.- mph) - 365
Engine Horsepower (bhp at test alt) - 2050
Stall speed (mph, at test alt) - 90

speed (mph TAS) @ 4500 feet ASL
300

CL
0.146573

D(p)
1089.133

D(i)
72.55357

CL^2
0.021484

CD(tot)
0.02301

Drag (tot)
1161.6864

thrust (lb)
1976.468

excess power (bhp)
814.7812

P.E.
0.78153

Data all came from the same sources.

Crumpp

VO101_Isegrim · « **Reply #171 on:** September 06, 2004, 01:19:07 AM »

Quote

Originally posted by Nashwan
JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate.

Here's a graph of what they estimated for Jl 165 at 18 lbs, along with other Spit VIIIs/IXs with Merlin 66:

JL 165 is in red.

And there Nashwan goes as usual. JL 165, "a standard Spitfire IX with Merlin 66 engine", as the report states, which Nashwan/Hop claims to be extraordinary slow, the worst performer, the sorriest Spit, anything but not that to choose, which according to him, had at least six engine changes, ten airframe overhauls and has to care for six hungry children to feed etc. etc. etc. - despite it`s report DOES NOT mention ANY problem with either the airframe or the engine... "a standard Spitfire IX with Merlin 66 engine", with a tropical filter, which was hardly uncommon, you see Spits with them in the Med, in Russia, in Normandy...

In fact, the tropicalized JL 165 does 389mph, the official RAF datasheet for the tropicalized MkIX say 386mph max speed, the tropicalized MkVIII in Australian reports show 393 mph max speed (with retractable tailwheel and the same new type Vokes filter)... but pray, do not use this data!

Instead, we should rely, he says, on the prototype BS 543, which had an experimental aircrew,that never seen production, that overperformed compared to normal in the tests :

"From BS 543 report:

..."It is a matter of interest that at sea level, Spitfire BS.354 with the RM-9SM engine, although nominally develping 50 B.H.P. more power than the Merlin 66 engines BS.543, is 7 m.p.h. slower, indicating either that the nominal powers were not realized and/or that there was a considerable difference between the drags of the two aircraft.

The powers of the RM-9SM and the Merlin 66 engines in F.S. gear should be identical, since the high speed supercharger gear ratio is the same. It will be seen that on the climb, the performance and boost pressures were similar, within the limits of experimental error, but in level flight above the full throttle height the Merlin 66 engine was developing about 1 lb/sq.inch higher boost pressure than the 9 SM engine, with a consequent higher full throttle height and improved performance. "

No, ignore that all, and use THIS prototype instead of the results for the standard Spitfire IX...

Or let`s use MA 648, another prototype that never were in service, with an experimental fuel pump, LOL.

Crumpp · « **Reply #172 on:** September 06, 2004, 09:02:42 AM »

Either way the story is the same.

The FW-190 had less parasitic drag than the Spitfire Mk IX no matter what varient.

Does anybody have good information on the Merlin 61 bhp?

My information is sketchy on the Merlin 61 and I am using Janes Merlin chart. According to Jane's the Merlin 61 developed 1565Hp @ 3000rpm at 12,250. This is close to the 13,000 feet ASL entry on table IV according to:

http://www.fourthfightergroup.com/eagles/bf274.html

If that Hp is correct then the FW-190A5 was 13mph faster on 165 less Horsepower at that altitude when using 1.42ata @ 2700U/min.

Crumpp

mw · « **Reply #173 on:** September 06, 2004, 09:13:49 AM »

Hi Gripen:

“Why the JL165, it performed way below average?”

Yes, any cursory review of a half dozen or more trials results will show that to be true. I’ve looked into that issue further and came up with the following report from Rolls-Royce showing results rather closer to average.

JL165 trials

367 @ 3,200’ M.S., 397 @14,400’ F.S.

Of the performance obtained the report states:

“A further point of note is the full throttle height at + 18 lbs. of boost which is somewhat lower than has previously been obtained with Merlin 66 engines. A check of the air intake efficiency was taken during the tests, a minimum figure of 94% in level flight being shown at + 25 lbs. sq.inch boost pressure. It would seem therefore that the full throttle height of this engine is low.”

A low FTH will give poorer performance.

In addition the condition with tropical filter is not representative of ADGB or ETO configuration.

“The engine was a standard production Merlin 66, the aircraft being a normal Spitfire IX, with 10'9" diameter Hydulignum propeller and standard tropical type of air intake, operating as temperate.”

Gripin, I agree the chart, while interesting and informative, lacks the precision to make accurate analysis.

It should be noted that switching from 100 to 150 octane fuel did not by itself cause a drop off in max top speed. It is apparent, when familiar with the facts, that a +18 Spit IX with max speed of 404 mph will still have a max speed of very close to if not exactly 404 mph when switched to 150 octane fuel.

Nashwan:

“If you use JL 165, you aren't going to get representitive figures for the Spit.”
Yes quite right, the trials data, while not representative, was useful to the RAF in determining that it was worthwhile to place in service these aircraft set up to run 150 octane fuel. It can be useful to us if not distorted and misrepresented

“Won't figures for a Spit at 18 lbs do?” I would think so. BS.543 or BS.310 might do. Perhaps BS.543 would be better given its operational history: BS.543 was built as a Mk V, converted to Mk IX (Merlin 61) at Rolls Royce, Hucknall. First flight 22-10-42. Transferred to AFDU, Duxford 8-11-42; AAEE, Boscombe Down 13-12-42 with Merlin 66 installed; Vickers Armstrong 22-2-43; 403 Sqdn. 9-6-43; 611 Sqdn. 10-6-43; 485 Sqdn. 6-7-43. Failed to return from operations 22-8-43. BS.310 had the all-round better numbers on average though.

Just as an aside, JL.165 ended up in North Africa which suggests they may have used 150 octane in the MTO. That's new on me.

p.s. nice graph and good work

Gripen, very impressive work you've done here.

Angus · « **Reply #174 on:** September 06, 2004, 09:43:42 AM »

Issy:
"JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate."

You should not make fun of this, this is quite evident from your chart!

There were roque Spits around, as well as rogue 109's as well

VO101_Isegrim · « **Reply #175 on:** September 06, 2004, 09:53:26 AM »

Quote

Originally posted by mw

JL165 trials

367 @ 3,200’ M.S., 397 @14,400’ F.S.

Of the performance obtained the report states:

“A further point of note is the full throttle height at + 18 lbs. of boost which is somewhat lower than has previously been obtained with Merlin 66 engines. A check of the air intake efficiency was taken during the tests, a minimum figure of 94% in level flight being shown at + 25 lbs. sq.inch boost pressure. It would seem therefore that the full throttle height of this engine is low.”

A low FTH will give poorer performace.

[/b]

Yep, too bad that even the new report on JL 165 did not show lower FTH than the others (save the experimental planes of course).

I guess there`s some wild consipracy going on, because we can see the JL 165 achieved FTH at 397 mph w. +18boost at 20 000 ft....

....and, for some odd reason, we also have the Merlin 66 power chart which actually shows that the FTH should be exactly at 20 000 feet at 400mph rammed speed.

In other words JL 165 reached exactly the FTH it should at +18lbs, ~20k ft. The "too low FTH" theory fails.

Furthermore, we see that JL 165 achieved ~14500 FTH at +25 lbs boost. Lookie again on the Merlin chart, the said FTH for +25lbs is again ~ 14 500 feet.

The "too low FTH" theory fails again. JL 165 reached exactly the same Full Throttle Heights in both MS and FS gear it should.

Apart from that, the whole case is pretty simple: Mike and Nashwan are so entitled to that the Spits should be superior to everything (but especially the 109), that they want to use performances measured on experimental machines.

Therefore they try, at every opportunity, discredit the JL 165 tests, despite the test notes it was a normal Spitfire in every aspect, with standard equipment, standard Merlin 66 engine, standard propellor, standard carburator and so on.

And so does, in view of this report, the "JL 165 was underperforming at +18lbs". Uh-oh, it did not.

The results from the other mid-1944 JL 165 report are ESTIMATES for +18lbs, worked out from +25lbs results. Previously MW and Nashwan claimed the JL 165 was "underperforming", pointing to these estimated figures in comparison with results obtained with experimental spitfires such as BS 543.

They believed the raise was far greater than actually, but this reports clearly points out the propellor could not take all the advanatage the increased power offered*, therefore their estimates for +18lbs understate the real speed of the aircraft.

* " It should be noted that there is no increase in the absolute speed obtained by the increase of boost, and it would appear that the efficiency of the propeller is somewhat reduced at the higher rating.

Quote

Originally posted by mw

In addition the condition with tropical filter is not representative of ADBG or ETO configuration.

[/B]

I guess Guppy can correct you on this, certainly it`s not hard to find filter equipped Spitfires in ETO, you know, the low mounted intake of the Spitty didn`t really like all the dust of Normandy`s provisional airfields.

Quote

“Won't figures for a Spit at 18 lbs do?” I would think so.

BS.543 or BS.310 might do.

Yep, both experimental planes with never-serialized equipment, ROFLOL. Perrrrfeeecct, - and typical Mike Williams.

Quote

Perhaps BS.543 would be better given its operational history: BS.543 was built as a Mk V, converted to Mk IX (Merlin 61) at Rolls Royce, Hucknall. First flight 22-10-42. Transferred to AFDU, Duxford 8-11-42; AAEE, Boscombe Down 13-12-42 with Merlin 66 installed; Vickers Armstrong 22-2-43; 403 Sqdn. 9-6-43; 611 Sqdn. 10-6-43; 485 Sqdn. 6-7-43. Failed to return from operations 22-8-43. BS.310 had the all-round better numbers on average though.

BS 543, Mr Williams means, the one with the never serialized Rotal XH54D-RM-S5 experimental airscrew.

Quote

Just as an aside, JL.165 ended up in North Africa which suggests they may have used 150 octane in the MTO. That's new on me.[/B]

Just like the rest of us, Mike, and we all wait in awe for your next flip flop making up the "150 grade Spitfires in ETO".

Like you did make up the +25lbs MkXIVs, which you know very well never existed in service, as their Griffon was derated to +21 lbs due to main bearing troubles.

VO101_Isegrim · « **Reply #176 on:** September 06, 2004, 09:59:06 AM »

Quote

Originally posted by Angus
Issy:
"JL 165 was far far slower than other tested Spit IXs, and had a far lower climb rate."

You should not make fun of this, this is quite evident from your chart!

There were roque Spits around, as well as rogue 109's as well

Hmm.. I plotted the newer - better performing - JL 165 tests against the results the Russians got on one of their (1000+) Mk IXLF, and the figures are in very close agreement.

I think Mike can screw his excuses, the JL 165 figures are in perfect agreement with the Merlin 66 charts FTH`s, AND they are in good agreement with performance results obtained in the USSR on a similiar L.F. Mk. IX.

And yes, I know compared to the Gustav the high alt performance is a bit disappointing, but it`s no shame, really.

straffo · « **Reply #177 on:** September 06, 2004, 10:02:33 AM »

Quote

Originally posted by gripen
English is not my native language. What is the SWAG test?

gripen

Scientific (or Silly) Wild bellybutton Guess. A term used by
technical teams when establishing high level sizings for large
projects.

Nashwan · « **Reply #178 on:** September 06, 2004, 11:49:48 AM »

Quote

Hey Nash, email me at burns@isholf.is and I'll reply with the attached XLS sheet for calculation of lift.

Thanks. The email should be on it's way in an hour or 2.

Quote

I will recheck the data Nashwan. Thanks for posting the comparision.

Cool. I find it difficult enough using these spreadsheets, how anyone can actually do the calculations themselves is beyond me.

Quote

And there Nashwan goes as usual. JL 165, "a standard Spitfire IX with Merlin 66 engine",

Which had also been used for lots of tests before A&AEE got their hands on it.

It's still much slower at most heights than any similar Spit I know of, and the climb rate is much worse.

Quote

In fact, the tropicalized JL 165 does 389mph, the official RAF datasheet for the tropicalized MkIX say 386mph max speed, the tropicalized MkVIII in Australian reports show 393 mph max speed (with retractable tailwheel and the same new type Vokes filter).

It's note a Vokes filter.

Seeing the new stuff MW has got of the RR tests of JL 165, it seems to me JL 165 had the standard VIII/IX tropical filter without blanking plates.

That's what JF 934 had, and the speeds RR got for JL 165 are pretty close to JF 934.

By the time A&AEE tested it, JL 165 was 12 mph slower at sea level, and had lost hundreds of ft/min in climb rate.

Quote

is a matter of interest that at sea level, Spitfire BS.354 with the RM-9SM engine, although nominally develping 50 B.H.P. more power than the Merlin 66 engines BS.543, is 7 m.p.h. slower, indicating either that the nominal powers were not realized and/or that there was a considerable difference between the drags of the two aircraft.

Yes, so? An experimental engine didn't perform as well as expected, and wasn't put into production. And this is an issue because....?

Quote

No, ignore that all, and use THIS prototype instead of the results for the standard Spitfire IX...

I'm still waiting for you to put JF 934 on your climb graph with the 109. You did after all claim you were just waiting for "serial production data", and JF 934 was a production aircraft shipped out to Australia for service.

Quote

Does anybody have good information on the Merlin 61 bhp?

My information is sketchy on the Merlin 61 and I am using Janes Merlin chart. According to Jane's the Merlin 61 developed 1565Hp @ 3000rpm at 12,250.

That's unrammed, rammed would be somewhat lower HP.

Quote

p.s. nice graph and good work

I spent some time on it, collecting various Spit test data from your site. The final one I went to add was MA 648, and what did I see when I clicked on it's performance graph?

Quote

The results from the other mid-1944 JL 165 report are ESTIMATES for +18lbs, worked out from +25lbs results. Previously MW and Nashwan claimed the JL 165 was "underperforming", pointing to these estimated figures in comparison with results obtained with experimental spitfires such as BS 543.

They believed the raise was far greater than actually, but this reports clearly points out the propellor could not take all the advanatage the increased power offered*, therefore their estimates for +18lbs understate the real speed of the aircraft.

This is coming from Isegrim, who has spent several years arguing that the estimated figures for JL 165 are the most accurate Spitfire Merlin 66 figures available. BS 543 and BS 551 should be ignored, because JL 165 was the only accurate data available. Now he's saying JL 165 data at 18 lbs isn't accurate at all.

Does this mean you are going to remove it from your climb graph, Isegrim?

Quote

I guess Guppy can correct you on this, certainly it`s not hard to find filter equipped Spitfires in ETO, you know, the low mounted intake of the Spitty didn`t really like all the dust of Normandy`s provisional airfields.

Which is probably why they started fitting blanking plates to the Spit air intake.

Spitfire the History gives figures for 3 Spit VIIIs tested with the tropical filter, first the normal Spit VIII type, then with blanking plates fitted.

JF 275 went from 397 mph to 402 mph, JL 163 from 367 to 372 (MS gear), JF 707 363 to 370 (MS gear), EN 654 (PR XI) 381 to 391.5 (MS gear) 410 to 421 (FS gear)

Angus · « **Reply #179 on:** September 06, 2004, 12:13:13 PM »

Izzy:
"Therefore they try, at every opportunity, discredit the JL 165 tests, despite the test notes it was a normal Spitfire in every aspect, with standard equipment, standard Merlin 66 engine, standard propellor, standard carburator and so on. "

Well, no matter what you say, it's a poor performer.

You are correct on one thing though. Increasing the boost to 25 doesn't really increase top speed. It will however drastically increase climb and acceleration. For increased top speed you'd have had to add a propeller blade for instance.

And here's one from you:
"Apart from that, the whole case is pretty simple: Mike and Nashwan are so entitled to that the Spits should be superior to everything (but especially the 109), that they want to use performances measured on experimental machines. "

You've hit your own nuts there Izzy. As it is, you yourself love to compare rather high performing 109's to the lower performing Spitties. Last thing I saw is your chart a tad above in this thread.
Why don't you swap that 109G2 out for a G6, and Swap the Spits to +25 Lf, Hf for alt, and +25 VIII and see the lines change:D

Of course the Alt performance is somewhat disappointing for a Spitty which is customized for LOWER ALT BANDS.

And the grand final:
"and we all wait in awe for your next flip flop making up the "150 grade Spitfires in ETO"

You're saying that there were none? Oh, I almost forgot, the Allies were low on fuel right, especially the good stuff