PDA

View Full Version : Spitfire MkIXc climb?



robban75
05-29-2004, 01:33 PM
I did a climbtest with the Spitfire MkIXc since it's one of the toughest adversaries for the Ta at high altitudes. Well, at least to me. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

Below are my climbtimes.

Crimea, full fuel, full power and boost, ~270km/h climbspeed.(Ta 152 climb in brackets)

1000m - 0:43 - 23.25m/sec
2000m - 1:24 - 24.39m/sec
3000m - 2:07 - 23.25m/sec
4000m - 2:50 - 23.25m/sec
5000m - 3:38 - 20.83m/sec
6000m - 4:26 - 21.27m/sec(17.24)
7000m - 5:20 - 18.51m/sec(13.69)
8000m - 6:25 - 15.38m/sec(13.33)
9000m - 7:50 - 11.76m/sec(12.33)

I never got the overheat warning on the Spit.

Are these climbtimes correct for a Spitfire MkIXc? Just wondering. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif

And please NO FLAMING!!!

http://members.chello.se/unni/D-9.JPG

When it comes to aircombat, I'd rather be lucky than good any day!

robban75
05-29-2004, 01:33 PM
I did a climbtest with the Spitfire MkIXc since it's one of the toughest adversaries for the Ta at high altitudes. Well, at least to me. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

Below are my climbtimes.

Crimea, full fuel, full power and boost, ~270km/h climbspeed.(Ta 152 climb in brackets)

1000m - 0:43 - 23.25m/sec
2000m - 1:24 - 24.39m/sec
3000m - 2:07 - 23.25m/sec
4000m - 2:50 - 23.25m/sec
5000m - 3:38 - 20.83m/sec
6000m - 4:26 - 21.27m/sec(17.24)
7000m - 5:20 - 18.51m/sec(13.69)
8000m - 6:25 - 15.38m/sec(13.33)
9000m - 7:50 - 11.76m/sec(12.33)

I never got the overheat warning on the Spit.

Are these climbtimes correct for a Spitfire MkIXc? Just wondering. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif

And please NO FLAMING!!!

http://members.chello.se/unni/D-9.JPG

When it comes to aircombat, I'd rather be lucky than good any day!

RAF74_Buzzsaw
05-29-2004, 02:15 PM
Salute

First of all, which model of Spitfire IXc was it that you tested?

It is not possible to replicate the Spitfire's climbing tests in the game. When the RAF tested their Spit IX's, they opening the radiator FULL for the entire test. Since the current Spit IX will only run on auto rad, it is impossible. And since the rad will be mostly closed when the climb begins, that will give a faster climb time in IL-2 tests.

The climb times for the Spit IX LF and HF are available here:

http://www.fourthfightergroup.com/eagles/bs543.html

Courtesy Mike Williams Spitfire site.

The times for the Spit IX LF are: (note the times are in fractions of minutes, ie. .45 is 27 seconds, and 1.5 is a minute and 30 seconds)

S.L. time -rate -speed - -
2,000 0.45 4640 176.5 +18.0
4,000 0.85 4660 182 " +18.0
6,000 1.3 4690 187 " +18.0
7,000* 1.5 4700 190 " +18.0
8,000 1.7 4560 193 " +17.0
10,000 2.15 4280 199 " +15.1
12,000 2.65 4000 205 " +13.4
14,000 3.15 3860 211.5 " +18.0
16,000 3.7 3860 218.5 " +18.0
18,000* 4.2 3860 223 168 +18.0
20,000 4.75 3560 224 163 +15.8
22,000 5.35 3270 225 158 +13.8
24,000 5.95 2970 226 153 +11.9
26,000 6.7 2700 227 148 +10.1
28,000 7.5 2400 229 143 +8.4
30,000 8.4 2120 230 138 +6.6
32,000 9.4 1830 231 133 +6.7
34,000 10.6 1550 232 128 +3.4
36,000 12.0 1260 232.5 123 +1.8
38,000 13.95 800 236 118 +0.4
40,000 17.55 300 237.5 113 -1.2


Times for the Spit IX HF are:

S.L. time -rate -speed - boost
0 0.45 4470 166.5 +18.5
4,000 0.9 4500 171.5 +18.5
6,000 1.35 4520 177 +18.5
8,000 1.8 4550 182 +18.5
10,000 2.2 4570 188 +18.5
11,400* 2.55 4580 192 +18.5
12,000 2.65 4500 194 +17.8
14,000 3.1 4180 200 +16.1
16,000 3.6 3880 207 +14.4
18,000 4.15 3780 213.5 +12.8
20,000 4.75 3500 220.5 +18.5
22,000 5.3 3520 229 +18.5
24,400* 5.95 3540 237 +18.5
26,000 6.45 3270 240 +16.5
28,000 7.05 2920 240 +14.2
30,000 7.8 2600 240 +12.1
32,000 8.6 2260 239.5 +10.0
34,000 9.6 1920 239 +8.0
36,000 10.1 1600 238.5 +6.1
38,000 12.25 1000 238.5 +4.3
40,000 15.3 400 241 -2.5

VW-IceFire
05-29-2004, 02:16 PM
According to Squadron Signals Spitfire in Action book...the IX is capable of climbing to 20,000 ft in 5-7 minutes. Of course I have no idea how they did the test or where the numbers come from but your test seems to show roughly that number.

http://home.cogeco.ca/~cczerneda/sigs/tmv-sig1.jpg
RCAF 412 Falcon Squadron - "Swift to Avenge"

hop2002
05-29-2004, 02:32 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>According to Squadron Signals Spitfire in Action book...the IX is capable of climbing to 20,000 ft in 5-7 minutes. Of course I have no idea how they did the test or where the numbers come from but your test seems to show roughly that number.
<HR></BLOCKQUOTE>

That sounds like a reduced power climb. When the RAF tested a Spit LF IX, it took 4 mins 45 sec to reach 20,000ft. The HF, tested at the same time, took almost exactly the same time. That's at 18 lbs boost (WEP) with radiators fully open throughout the climb.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Are these climbtimes correct for a Spitfire MkIXc? Just wondering.<HR></BLOCKQUOTE>

The low level figures are about right for an LF IX with rad flaps open, as Buzzsaw says. The high level figures are a bit too high for open rads.

Closing the radiators improved climb rate by approx 10%. That would make the low level figures too low, the high level figures about right.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>I never got the overheat warning on the Spit<HR></BLOCKQUOTE>

You shouldn't. The Spit cooling report done at 25 lbs boost (our Spit is limited to 18 lbs) showed that in temperate summer conditions, a full power climb from 2,000ft to 32,000ft with rad flaps shut didn't overheat the plane. And that's with closed radiators and higher manifold pressure.

Kurfurst__
05-29-2004, 02:46 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by hop2002:
That sounds like a reduced power climb. When the RAF tested a Spit LF IX, it took 4 mins 45 sec to reach 20,000ft. The HF, tested at the same time, took almost exactly the same time. That's at 18 lbs boost (WEP) with radiators fully open throughout the climb.<HR></BLOCKQUOTE>

These were prototype aircraft, not serially produced machines. When tested later on, serially produced HF and LF Spitfires shows somewhat lower climb rates, perhaps because of changes in the engine supercharger in the final version.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>I never got the overheat warning on the Spit<HR></BLOCKQUOTE>

You shouldn't. The Spit cooling report done at 25 lbs boost (our Spit is limited to 18 lbs) showed that in temperate summer conditions, a full power climb from 2,000ft to 32,000ft with rad flaps shut didn't overheat the plane. And that's with closed radiators and higher manifold pressure.<HR></BLOCKQUOTE>

Sorry that`s incorrect. The Spitfire Mk IX manual states 5 minutes limit for the maximum 18 or 25 lbs boost. Statements like the 'Spitfire shouldn`t overheat' can`t be taken seriously. Every plane overheats at max. power. Even Spitfires, Hop. As for the report you mention, it does not give engine temperatures at the end of the time if I recall correctly, it`s calculation of 'radiator suitability', using the requirements laid down by the engineers who did this test. Quite different from the a/c never reaching a given temperature, as you state. Why the 5-min limit on the engine, then?

http://www.x-plane.org/users/isegrim/fat-furred%20tigerB.jpg

"We've got the finest tanks in the world. We just love to see the German Royal Tiger come up on the field".
- Lt. Gen. George S. Patton, Jr. Febuary 1945.

"One day a Tiger Royal got within 150 yards of my tanks and knocked me out. Five of our tanks opened up on him at ranges of 200 to 600 yards and got 5 or 6 hits on the front of the Tiger. They all just glanced off and the Tiger backed off and got away. If we had a tank like that Tiger, we would all be home today."
- Sgt. Clyde D. Brunson, US Army, Tank Commander, February 1945

hop2002
05-29-2004, 03:37 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>When tested later on, serially produced HF and LF Spitfires shows somewhat lower climb rates, perhaps because of changes in the engine supercharger in the final version.<HR></BLOCKQUOTE>

Source?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Sorry that`s incorrect. The Spitfire Mk IX manual states 5 minutes limit for the maximum 18 or 25 lbs boost. Statements like the 'Spitfire shouldn`t overheat' can`t be taken seriously. Every plane overheats at max. power. Even Spitfires, Hop.<HR></BLOCKQUOTE>

Source for this as well please. The manual limits WEP to 18 lbs boost, but doesn't say overheating will occur. The test done at 25 lbs boost shows no overheating on the climb under temperate conditions, overheating only under tropical conditions on the climb.

The plane is so far from overheating in level flight there's no way it could come close at 18 lbs in level flight with rads open.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As for the report you mention, it does not give engine temperatures at the end of the time if I recall correctly, it`s calculation of 'radiator suitability', using the requirements laid down by the engineers who did this test.<HR></BLOCKQUOTE>

They give a very simple equation for radiator suitability:

suitability = (normal max permissable temp - standard atmosphere summer temp) / (coolant temp at exit from engine - actual air temp)

Maximum coolant temp is 135c for wep, 105c for cruising.

Suitability was 1.12 - 1.18 climb rads open, 0.99 rads shut, 1.32 all out level at 13,500ft rads shut, 1.36 all out level at 3000ft rads shut, all in temperate summer conditions.

Solving that for 1 example, all out level at 3,000ft, assuming air temp of 8.5c:

1.36 = (135 - 8.5) / (101.5 - 8.5)

That means assuming the temp was the same as the current standard atmos, at 3,000ft after cruising for 10 min and 5 mins at 25 lbs boost, the coolant temperate at the outlet from the engine, ie the hotest part of the coolant cycle, before entering the rad, was 101.5 c, with a permitted max of 135 c. The actual temp was lower than the permitted cruising temp, which was allowed to be maintained indefinately.

Obviously at the end of a 25 lbs boost climb from 2,000ft to 32,000ft with rads shut, the coolant had reached maximum permitted temp, and even slightly exceeded it, but that's with rads forced shut in a climb at 25 lbs boost, a combination of the 3 worst factors.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Quite different from the a/c never reaching a given temperature, as you state.<HR></BLOCKQUOTE>

It's not different at all, it's a simple equation that gives the effectiveness of the radiator. If the radiator effectiveness is over 1, the coolant is not at the permitted maximum, if the effectiveness is under 1 the coolant is overheated.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Why the 5-min limit on the engine, then?
<HR></BLOCKQUOTE>

To reduce wear. Pyro (one of the creators of Aces High) posted this on the AH boards, from the P-51 manual:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>It is often asked what the consequences will be if the 5-minute limit at Take-off Power is exceeded. Another frequent inquiry is how long a period must be allowed after the specified time limit has elapsed until Take-off Power can be used. These questions are difficult to answer, since the time limit specified does not mean that engine damage will occur if the limit is exceeded. Instead, the limit means that the total operating time at high power should be kept to a reasonable minimum in the interest of prolonging engine life.

It is generally accepted that high-power operation of an engine results in increased wear and necessitates more frequent overhaul than low-power operation. However, it is apparent that a certain percentage of operating time must be at full power. The engine manufacturer allows for this in qualification tests in which much of the running is done at Take-off Power to prove ability to withstand the resulting loads. It is established in these runs that the engine will handle sustained high power without damage. Nevertheless, it is still the aim of the manufacturer and to the best interest of the pilot to keep within reasonable values the amount of high-power time accumulated in the field. The most satisfactory method for accomplishing this is to establish time limits that will keep pilots constantly aware of the desire to hold high-power periods to the shortest period that the flight plan will allow, so that the total accumulated time and resulting wear can be kept to a minimum. <HR></BLOCKQUOTE>

The cooling trials make it clear that overheating will not occur in 5 mins, unless you do long climbs with rads shut. If the 5 min limit was down to cooling, then it wouldn't be a time limit, it would be a temp limit, something along the lines of:

Combat 18 lbs 3000 rpm 135c coolant temp. In fact, Spit manuals gave both a maximum temperature limit and a time limit, indicating that the two reasons are seperate. If the time limit was to prevent overheating, why give an overheating limit? Or why not just give the overheating limit, and not the time limit?

As the quote from the P-51 manual says:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>the time limit specified does not mean that engine damage will occur if the limit is exceeded. Instead, the limit means that the total operating time at high power should be kept to a reasonable minimum in the interest of prolonging engine life.
<HR></BLOCKQUOTE>

p1ngu666
05-29-2004, 04:13 PM
time doesnt take into acount the cooling. u could be doing 200kmph, or 500 or even faster http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif
this does effect the c/w http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif
ive always wondered about overheat at high speed, cos thats alot of airflow at highspeeds.
www.overclockers.com (http://www.overclockers.com) has a c/w thingy somewhere http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif
its usefulhttp://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

http://www.pingu666.modded.me.uk/mysig3.jpg
&lt;123_GWood_JG123&gt; NO SPAM!

Kurfurst__
05-29-2004, 04:42 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by hop2002:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>When tested later on, serially produced HF and LF Spitfires shows somewhat lower climb rates, perhaps because of changes in the engine supercharger in the final version.<HR></BLOCKQUOTE>

Source?<HR></BLOCKQUOTE>

Look at the the performance tests, Hop. Even you can read curves, can`t you? I just noted that the figures your quoted are for prototypes, not serial planes, and it`s the best interest of everyone who wants to know the reality, to understand that. For those who come up with an agenda, may remain silent about that part..



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
Source for this as well please. The manual limits WEP to 18 lbs boost, but doesn't say overheating will occur..<HR></BLOCKQUOTE>

Well it says the +18 lbs boost is limited to 5 minutes time. I believe it`s quite clear. I think it`s quite futile to press an aganda like the 'Spitfire should never overheat, as it was all Gold'.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
The test done at 25 lbs boost shows no overheating on the climb under temperate conditions, overheating only under tropical conditions on the climb. <HR></BLOCKQUOTE>

Define 'overheating'.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The plane is so far from overheating in level flight there's no way it could come close at 18 lbs in level flight with rads open.<HR></BLOCKQUOTE>

Well that`s probably true, it`s very hard to overheat a plane with it`s radiators fully open. Any plane, not just the Spits, if you imply that. Of course, that comes with a very severe speed loss, 40-50mph minus, that`s why speed runs are done with closed radiators, which on the other hand, overheat the plane more quickly.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As for the report you mention, it does not give engine temperatures at the end of the time if I recall correctly, it`s calculation of 'radiator suitability', using the requirements laid down by the engineers who did this test.<HR></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>They give a very simple equation for radiator suitability:

suitability = (normal max permissable temp - standard atmosphere summer temp) / (coolant temp at exit from engine - actual air temp)

Maximum coolant temp is 135c for wep, 105c for cruising.

Suitability was 1.12 - 1.18 climb rads open, 0.99 rads shut, 1.32 all out level at 13,500ft rads shut, 1.36 all out level at 3000ft rads shut, all in temperate summer conditions.

Solving that for 1 example, all out level at 3,000ft, assuming air temp of 8.5c:

1.36 = (135 - 8.5) / (101.5 - 8.5).<HR></BLOCKQUOTE>


Ahhh, this explains it. I wonder, in which country is the air temperature a whole 8.5 Celsius DURING THE SUMMER ? That explains why the radiators did not overheat, and were 'suitable', their 'summer standard' was very low temperture compared to what temps we experience in real life. Well, perhaps it`s true for Northern England, or Iceland, but not any normal country, to have 8.5 degrees celsius during the summer.. here`s it`s rather typicall 25-30 degrees celsius on avarage. As I said, the conslusions drawn this test are 90% dependant on the definitions you want to use.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The actual temp was lower than the permitted cruising temp, which was allowed to be maintained indefinately.<HR></BLOCKQUOTE>

Hardly, the engine will fall apart from overloading very soon. Remember it`s a short time WEP, not normal power (which was IIRC 7-12 lbs boost, at a much reduced RPM and power).

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Obviously at the end of a 25 lbs boost climb from 2,000ft to 32,000ft with rads shut, the coolant had reached maximum permitted temp, and even slightly exceeded it, but that's with rads forced shut in a climb at 25 lbs boost, a combination of the 3 worst factors.<HR></BLOCKQUOTE>

Not really, the only bad factor are the force-closed rads. First being the Spit not being able to hold +25 lbs at most altitudes, ie. the MS gear can only hold it for 500 feet, that`s basically nothing, 5 seconds or so... Second reason being the fact that the outside temperature is much lower as you go up, again helping you cooling down more than at low levels. It may look to be something extraordinary thing on the surface, but it`s rather standard issue. Interestingly enough, 109 climb test also show that much more closed radiators could maintain the same temperature during climb at the higher altitudes, for the same reasons. It all works the same.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Why the 5-min limit on the engine, then?<HR></BLOCKQUOTE>

To reduce wear. Pyro (one of the creators of Aces High) posted this on the AH boards, from the P-51 manual:
<HR></BLOCKQUOTE>

Interesting. Do you imply with that no aircraft in the game should take damage at all to it`s engine after greatly exceeding it`s prescribed time limit at WEP, as given by the manual ?



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Combat 18 lbs 3000 rpm 135c coolant temp. In fact, Spit manuals gave both a maximum temperature limit and a time limit, indicating that the two reasons are seperate.<HR></BLOCKQUOTE>

Interesting Hop. Overheating is a seperate issue than how much time you spend at maximum power? For one brief moment, I belived that heat is generated is related to the power output of the engine.. But then, almost every a/c manual gives seperate time limits and coolant limits. Does his mean no a/c should ever overheat because of that..?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>If the time limit was to prevent overheating, why give an overheating limit?
Or why not just give the overheating limit, and not the time limit?
<HR></BLOCKQUOTE>

That`s rather simple. You can start with an engine already hot, and reach the critical temperature limit well before than your time limit expires. Such time limits are generally refer for normal starting engine temperatures. In example, if your critical temp is 135 celsius, and normal temp is 95 celsius, you may need 5 minutes to go 40 celsius up while using maximum power. But if your engine is already at 120 celcius when you turn WEP on, you will be at max. temperature in 1 or 2 mins.

In real life, of course, it`s far more complicated, as manufacturers may give very different numbers, ie. a certain max. temperature that could be held for a certain amount of time, ie. 10 mins, which also varies with temperature, or they can simply give a never-exceed temperature which seems to be the case in the Merlin engines.

http://www.x-plane.org/users/isegrim/fat-furred%20tigerB.jpg

"We've got the finest tanks in the world. We just love to see the German Royal Tiger come up on the field".
- Lt. Gen. George S. Patton, Jr. Febuary 1945.

"One day a Tiger Royal got within 150 yards of my tanks and knocked me out. Five of our tanks opened up on him at ranges of 200 to 600 yards and got 5 or 6 hits on the front of the Tiger. They all just glanced off and the Tiger backed off and got away. If we had a tank like that Tiger, we would all be home today."
- Sgt. Clyde D. Brunson, US Army, Tank Commander, February 1945

Magister__Ludi
05-29-2004, 05:06 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by hop2002:

As the quote from the P-51 manual says:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>the time limit specified does not mean that engine damage will occur if the limit is exceeded. Instead, the limit means that the total operating time at high power should be kept to a reasonable minimum in the interest of prolonging engine life.
<HR></BLOCKQUOTE><HR></BLOCKQUOTE>


This is valid for all the planes, the time limit is only orientative, the temp gauge is the real indicator. BUT in standard conditions overheating occured aprox after the time limit interval specified in the manual. Since the manual clearly states 5 minutes at 67" MP (equiv to 18lb boost) then it should overheat as any other engine in the game, that is at the limit specified in the manual. More complex overheating calculations are not possible with current hardware.

hop2002
05-29-2004, 06:16 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Look at the the performance tests, Hop. Even you can read curves, can`t you? I just noted that the figures your quoted are for prototypes, not serial planes, and it`s the best interest of everyone who wants to know the reality, to understand that. For those who come up with an agenda, may remain silent about that part..<HR></BLOCKQUOTE>

So you're backing away from the changes in the supercharger story?

All planes show differences between individual models. Apart from Jl 165, the subsequent tests I've seen are all within the normal range you'd expect. For example, 4 different Spit IXs were tested, all between 335 and 341 mph at sea level.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Well it says the +18 lbs boost is limited to 5 minutes time. I believe it`s quite clear. I think it`s quite futile to press an aganda like the 'Spitfire should never overheat, as it was all Gold'.<HR></BLOCKQUOTE>

And the cooling report makes it quite clear overheating wasn't the reason it was limited to 5 mins.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Define 'overheating'.<HR></BLOCKQUOTE>

Exceeding permissible temperatures. The cooling report makes it quite clear at 25 lbs boost it didn't exceed permissible temps, except in extended full power climbs with rad flaps shut.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Well that`s probably true, it`s very hard to overheat a plane with it`s radiators fully open. Any plane, not just the Spits, if you imply that. Of course, that comes with a very severe speed loss, 40-50mph minus, that`s why speed runs are done with closed radiators, which on the other hand, overheat the plane more quickly.
<HR></BLOCKQUOTE>

The point is if overheating was the reason for the 5 min limit, and with the Spits having auto radiators, there'd be no need for the limit, because the radiators would open and the engine wouldn't overheat.

In actual fact, the report shows the engine was nowhere near overheating after 5 mins at maximum speed with rads shut.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Ahhh, this explains it. I wonder, in which country is the air temperature a whole 8.5 Celsius DURING THE SUMMER ?<HR></BLOCKQUOTE>

In any country with standard atmosphere, at 3,000ft which is the altitude the speed run was carried out at. Note the 8.5c figure is one I'm assuming, it could be double that, but the radiator suitability remains the same. The report doesn't give the actual figure.

Where I may have made a mistake is assuming the standard atmosphere is average summer temp, whereas it may be a year round average.

But note that's my assumption, not the report's.

Note that increasing the temp doesn't make that much difference. Doubling, to 17 c, we get:

1.36 = (135c - 17) / (103.75 - 17)

Coolant temp, at 17 c, equals 103.75 c, max permissible is 135c.

And with standard atmosphere, to get a temp at 17c at 3000ft requires 30c at sea level.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>That explains why the radiators did not overheat, and were 'suitable', their 'summer standard' was very low temperture compared to what temps we experience in real life. Well, perhaps it`s true for Northern England, or Iceland, but not any normal country, to have 8.5 degrees celsius during the summer.. here`s it`s rather typicall 25-30 degrees celsius on avarage. <HR></BLOCKQUOTE>

No, the summer standard was the standard atmosphere in use at the time. Note that even the tropical summer standard atmosphere didn't come close to overheating.

The 8.5c figure is from the current standard atmosphere at 3,000ft.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As I said, the conslusions drawn this test are 90% dependant on the definitions you want to use.
<HR></BLOCKQUOTE>

Use any reasonable assumption you want to assume. Assume standard summer temp used was 5c at 3000ft, which would be rougly 7.5c at sea level. Ridiculously low figure, I think you'll agree. The coolant temp then becomes:

1.36 = (135c - 5) / (100.5 - 5)
Coolant temp = 100.5

Or use the 17c figure I used earlier, which equals a sea level temp of about 30c:

1.36 = (135c - 17) / (103.75 - 17)
Coolant temp = 103.75

Those are two extremes, are you really suggesting the RAf would have defined a standard atmosphere where the summer temp at sea level was not between 7.5c and 30c?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Hardly, the engine will fall apart from overloading very soon. Remember it`s a short time WEP, not normal power (which was IIRC 7-12 lbs boost, at a much reduced RPM and power).
<HR></BLOCKQUOTE>

No, cruising temp was allowed to be maintained indefinately. If the coolant temp was within the limit approved for cruising conditions, how can the coolant temp be the limit for wep?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Not really, the only bad factor are the force-closed rads. First being the Spit not being able to hold +25 lbs at most altitudes, ie. the MS gear can only hold it for 500 feet, that`s basically nothing, 5 seconds or so...<HR></BLOCKQUOTE>

This was an FS gear climb, which could maintain 25lbs to 11,400 ft.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Second reason being the fact that the outside temperature is much lower as you go up, again helping you cooling down more than at low levels.<HR></BLOCKQUOTE>

That's true of the game as well. By worst conditions, I was pointing out areas where the tests had worse conditions than Robban's tests.

Robban's test had auto rads, the real life test had closed rads. Robban was running at 18 lbs, the real plane at 25 lbs. The real plane only overheated in tropical conditions (it reached maximum almost at the end of the climb), Robban's test was under temperate conditions.

That's three factors where Robban's test was less severe than the real life test.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Interesting. Do you imply with that no aircraft in the game should take damage at all to it`s engine after greatly exceeding it`s prescribed time limit at WEP, as given by the manual ?
<HR></BLOCKQUOTE>

I can't say no engine, because I don't know about other engines. But the Spit certainly shouldn't take instant damage, and shouldn't overheatafter 5 mins at WEP, unless you're climbing with rads shut in tropical conditions, which you can't do in the game (shut rads, that is)

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Interesting Hop. Overheating is a seperate issue than how much time you spend at maximum power? <HR></BLOCKQUOTE>

It is in the Spit IX. The fact that the limit was the same 5 mins at 18lbs or 25lbs should tell you that.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>For one brief moment, I belived that heat is generated is related to the power output of the engine<HR></BLOCKQUOTE>

Exactly. So heat generated is going to be much greater at 25 lbs than at 18lbs, isn't it?

Yet the limits are the same.

Heat is generated by the engine, taken away by the cooling system. If your cooling system is powerfull enough, it can take away enough heat to stop the engine overheating at any given power level.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>But then, almost every a/c manual gives seperate time limits and coolant limits. Does his mean no a/c should ever overheat because of that..?<HR></BLOCKQUOTE>

I don't know, I haven't seen their cooling reports. I have seen the Spit cooling report, though, and it's quite clear that the plane was in no danger of overheating in level flight at maximum power.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>This is valid for all the planes, the time limit is only orientative, the temp gauge is the real indicator. BUT in standard conditions overheating occured aprox after the time limit interval specified in the manual. <HR></BLOCKQUOTE>

No, the cooling report shows that after 10 mins cruise, radiators shut, which will bring coolant up to temperature, followed by 5 mins all out, at 25 lbs, not 18 (81" not 67"), the coolant is still way off maximum temp. In fact, the coolant is still below the maximum coolant temp permitted for cruising.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Since the manual clearly states 5 minutes at 67" MP (equiv to 18lb boost) then it should overheat as any other engine in the game, that is at the limit specified in the manual.<HR></BLOCKQUOTE>

Consider another point. 5 mins is the maximum wep time. You can spend that climbing or flying at 400 mph in level flight. Any difference between the cooling in level flight and climb? Obviously, level flight is going to cool the plane far more, so the WEP limit should be longer, yes?

The Spit had adequate cooling rad flaps closed for 25 lbs boost climbs for 5 minutes in temperate conditions, just.

It had far more than adequate for 5 mins rad flaps closed maximum power in level flight.

That's why the report gives radiator suitability as 1.36 level flight 3,000ft temperate summer rad flaps closed, 0.99 climb temperate summer rad flaps closed, both at 25 lbs.

CV8_Dudeness
05-29-2004, 07:28 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74BuzzsawXO:
Salute

First of all, which model of Spitfire IXc was it that you tested?

It is not possible to replicate the Spitfire's climbing tests in the game. When the RAF tested their Spit IX's, they opening the radiator FULL for the entire test.
<HR></BLOCKQUOTE>

hello Buzzsaw

the Spitfire Mk9 ingame should climb relative to the times acheieved IRL wouldnt you say ?

cant fly full power without the rad opening when its in Auto

VW-IceFire
05-29-2004, 10:56 PM
I may be a bit slow but the Mark IX in FB is climbing very closely with what the stats say it should. Thats OK in my book for the Spitfire and any other plane.

http://home.cogeco.ca/~cczerneda/sigs/tmv-sig1.jpg
RCAF 412 Falcon Squadron - "Swift to Avenge"

robban75
05-30-2004, 02:57 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74BuzzsawXO:
Salute

First of all, which model of Spitfire IXc was it that you tested?

It is not possible to replicate the Spitfire's climbing tests in the game. When the RAF tested their Spit IX's, they opening the radiator FULL for the entire test. Since the current Spit IX will only run on auto rad, it is impossible. And since the rad will be mostly closed when the climb begins, that will give a faster climb time in IL-2 tests.
<HR></BLOCKQUOTE>

Hi Buzzsaw!

I tested the first MkIXc Spit avaliable after the MkVb on the planes list.

In FB open rads have little effect on climb performance. I made a climbtest with the K-4 with fully open and closed rads, the difference was IIRC not even half a meter/sec. Rads only show a serious performance drop at the higher speeds, and unfortunatelly not during slow speed climbs http://ubbxforums.ubi.com/images/smiley/16x16_smiley-sad.gif.

http://members.chello.se/unni/D-9.JPG

When it comes to aircombat, I'd rather be lucky than good any day!

Kurfurst__
05-30-2004, 04:09 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by hop2002:
So you're backing away from the changes in the supercharger story?<HR></BLOCKQUOTE>

Not at all, it`s clearly indicated by the subsequent reports, that the tested BS 543 Mk IX prototype was far from representative from that of the serially produced Mk IXs that followed. Apart from the fact it had an experimental prop fitted, the rated altitude was also much higher than the other`s, indicating a different supercharger setup - the engine was still experimental at time of the tests, coded RM-10 SM.

The prototype plane you refer to had level speed FTH of 22 100 ft... all other serial planes that followed developed 19 500 (BS 310) or 19 300 (JL 165), JL 275, a slightly different and cleaner Mk VIII airframe with Merlin 66 also had it at 20 200ft.

It`s also noted : ".. the engine of BS.543 has full throttle heights far above average... "

Which might explain why proto Mk IX BS 543 was oddly faster than the Mk VIII JF 275, ie. 409 mph vs. 405 mph. Als

Even if you refer to the 400mph rammed HP chart of the Merlin 66, it shows a FTH of ~ 20k ft at 18 lbs.. Nobody should expect more with an engine that develops a static output at 16 000 ft, ie. the rated altitude of the Merlin 66 at +18 lbs. 4000 ft gain in FTH due to ram is what you would expect and in fact experienced with others, under such moderate speeds and altitude.

Indicating this plane you refer to was VERY different from that of the Mk IX LF. Same goes for the prototype Mk IX HF tested alongside, which produced very different results than the later planes tested there.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
All planes show differences between individual models. Apart from Jl 165, the subsequent tests I've seen are all within the normal range you'd expect. For example, 4 different Spit IXs were tested, all between 335 and 341 mph at sea level.<HR></BLOCKQUOTE>

Not speaking of SL speeds here, these would tell next to zero about the superchargers installed. I am talking bout FTHs here, which are very much the same on the rammed Merlin power chart, and three other Merlin 66 aircraft, JL 165, BS 310, and JL 275, all being 19500-20000 ft in level flight vs. the 22 100 ft of the prototype you like to come up with.

These, and the performance figures obtained, clearly shows there was a change in s/c gear ratios with the final production aircraft compared to the prototypes.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>And the cooling report makes it quite clear overheating wasn't the reason it was limited to 5 mins.<HR></BLOCKQUOTE>

Could you please qoute that part which makes it clear, sadly I cannot find any reference to that in the report.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>In actual fact, the report shows the engine was nowhere near overheating after 5 mins at maximum speed with rads shut.<HR></BLOCKQUOTE>

The actual fact, as already pointed out, that this statement of the report is based on what conditions the British considered overheating. If they choosed surrealistically optimum values, the 'radiator suitability' calculated value would not give any clue about real life experience.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>In any country with standard atmosphere, at 3,000ft which is the altitude the speed run was carried out at. Note the 8.5c figure is one I'm assuming, it could be double that, but the radiator suitability remains the same. The report doesn't give the actual figure.

Where I may have made a mistake is assuming the standard atmosphere is average summer temp, whereas it may be a year round average.
But note that's my assumption, not the report's.<HR></BLOCKQUOTE>

In short, we have no idea on what conditions, ie. very relevant outside temperatures the report bases it`s statements, and are left at uncretain assumptions.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As I said, the conslusions drawn this test are 90% dependant on the definitions you want to use.
<HR></BLOCKQUOTE>

Use any reasonable assumption you want to assume. Assume standard summer temp used was 5c at 3000ft, which would be rougly 7.5c at sea level. Ridiculously low figure, I think you'll agree. The coolant temp then becomes:

1.36 = (135c - 5) / (100.5 - 5)
Coolant temp = 100.5

Or use the 17c figure I used earlier, which equals a sea level temp of about 30c:

1.36 = (135c - 17) / (103.75 - 17)
Coolant temp = 103.75

Those are two extremes, are you really suggesting the RAf would have defined a standard atmosphere where the summer temp at sea level was not between 7.5c and 30c? <HR></BLOCKQUOTE>[/QUOTE]

Sorry it would be the same then as soon you changed the outside temperature, the ability of the radiator will change and you won`t get the same results anymore - the higher the outside temperature will be, the higher the exit temps from the rads shall be as well, and the radiator suitability value will decrease. You assume the enter/exit temperatures will be the same, really they won`t be.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Hardly, the engine will fall apart from overloading very soon. Remember it`s a short time WEP, not normal power (which was IIRC 7-12 lbs boost, at a much reduced RPM and power).
<HR></BLOCKQUOTE>

No, cruising temp was allowed to be maintained indefinately. If the coolant temp was within the limit approved for cruising conditions, how can the coolant temp be the limit for wep?
<HR></BLOCKQUOTE>

As alrady pointed it, it`s not neccesarilily always the engine temp, but it has a great deal to do with it. There`s also engine load, which the main bearing and other pieces won`t support for long without breaking. Crusing conditions refered to very low powers and engine load, that`s why it could be maintained w/o limits. But the load is also effected by engine temperature.. it`s not a seperate issue. But, suffice to know, that as per the engine manufacturers own limitations, the Merlin 66 should not be run on max power for more than 5 minutes, for whatever reason.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Not really, the only bad factor are the force-closed rads. First being the Spit not being able to hold +25 lbs at most altitudes, ie. the MS gear can only hold it for 500 feet, that`s basically nothing, 5 seconds or so...<HR></BLOCKQUOTE>

This was an FS gear climb, which could maintain 25lbs to 11,400 ft.<HR></BLOCKQUOTE>


Regardless Hop, we still don`t having the 'worst' conditions as you state. As per the climbing trials of JL 165 with closed rads, even from SL to 11 400 ft it took only about 2.39 mins to reach that high, above which the boost fell of, ie. the plane was no longer developing maximum power or heat above that height. And that`s slightly less than HALF of the 5 minutes the Merlin 66 was allowed to run at maximum power...

Stating that the Spit IX should not overheat at all after 5 minutes at max power because it did not overheat after half that time in a climb is rather streching it, don`t you think ?



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
I can't say no engine, because I don't know about other engines. But the Spit certainly shouldn't take instant damage, and shouldn't overheatafter 5 mins at WEP, unless you're climbing with rads shut in tropical conditions, which you can't do in the game (shut rads, that is)
<HR></BLOCKQUOTE>

I think you should first prove the claim that the Spit should never overheat. To start, it just plain sounds rather ridiculus. But apart from that, the game engine seem to model the maximum WEP time that can be spent on max power based on engine overheating, engine load does not seem to be taken into consideration. Therefore eliminating overheating completely for a plane also gives a totally false picture that it can run at max power indefinietely, whereas it could really run for 5 mins on it (safely).



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Interesting Hop. Overheating is a seperate issue than how much time you spend at maximum power? <HR></BLOCKQUOTE>

It is in the Spit IX. The fact that the limit was the same 5 mins at 18lbs or 25lbs should tell you that.<HR></BLOCKQUOTE>

Not really. Using 25 lbs boost required modifications on the Merlin 66, it was not the same engine as the ones that run on +18 lbs.

http://www.x-plane.org/users/isegrim/fat-furred%20tigerB.jpg

"We've got the finest tanks in the world. We just love to see the German Royal Tiger come up on the field".
- Lt. Gen. George S. Patton, Jr. Febuary 1945.

"One day a Tiger Royal got within 150 yards of my tanks and knocked me out. Five of our tanks opened up on him at ranges of 200 to 600 yards and got 5 or 6 hits on the front of the Tiger. They all just glanced off and the Tiger backed off and got away. If we had a tank like that Tiger, we would all be home today."
- Sgt. Clyde D. Brunson, US Army, Tank Commander, February 1945

Functio
05-30-2004, 04:20 AM
WRT to radiators at high altitude - remember that FB doesn't model undercooling.

hop2002
05-30-2004, 06:04 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Not at all, it`s clearly indicated by the subsequent reports, that the tested BS 543 Mk IX prototype was far from representative from that of the serially produced Mk IXs that followed. Apart from the fact it had an experimental prop fitted, the rated altitude was also much higher than the other`s, indicating a different supercharger setup - the engine was still experimental at time of the tests, coded RM-10 SM.
<HR></BLOCKQUOTE>

The rated altitude was higher, but the performance below critical alt was lower. Look at these again:

http://www.onpoi.net/ah/pics/users/282_1082729993_spitixspeeds4.gif

BS543 has a higher critical alt, but is a fair bit slower below critical alt in FS gear. The only substantial difference is in ms gear critical alt, but I've never seen anything to say the supercharger was changed, indeed other reports that comment on the differences never say that the supercharger was changed, which would be bizarre if that was the reason for the change.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>It`s also noted : ".. the engine of BS.543 has full throttle heights far above average... "

<HR></BLOCKQUOTE>

Does that statement make any sense whatsoever if BS543 had a different supercharger setup? No.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Which might explain why proto Mk IX BS 543 was oddly faster than the Mk VIII JF 275, ie. 409 mph vs. 405 mph. <HR></BLOCKQUOTE>

Oddly faster? You call a speed difference of just under 1% between 2 planes odd? Natural variation would show much greater differences than that.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Indicating this plane you refer to was VERY different from that of the Mk IX LF. Same goes for the prototype Mk IX HF tested alongside, which produced very different results than the later planes tested there.
<HR></BLOCKQUOTE>

They note some changes to the carb on the Merlin 70, I've never seen anything to suggest a change to the supercharger on the Merlin 66.

If you're calling performance differences of less than 1% between 2 planes "odd", then your standards for commonality between tested machines are obviously much higher than any WW2 air force's.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Not speaking of SL speeds here, these would tell next to zero about the superchargers installed. I am talking bout FTHs here, which are very much the same on the rammed Merlin power chart, and three other Merlin 66 aircraft, JL 165, BS 310, and JL 275, all being 19500-20000 ft in level flight vs. the 22 100 ft of the prototype you like to come up with.
<HR></BLOCKQUOTE>

Which was also slower below FTH than BS310 and JL275, by a noticeable margin. Throw in MA 648 as well, and those 3 were within 2 mph of each other between 15 and 19k, with BS543 6 mph slower.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>These, and the performance figures obtained, clearly shows there was a change in s/c gear ratios with the final production aircraft compared to the prototypes.
<HR></BLOCKQUOTE>

That's never mentioned anywhere? Indeed, they note it has FTH heights above average, without noting that it's because the supercharger was changed? Come on, that's like saying this particular car is strangely faster, without noting it's been fitted with a turbo.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> the cooling report makes it quite clear overheating wasn't the reason it was limited to 5 mins.
--------------------------------------------------------------------------------



Could you please qoute that part which makes it clear, sadly I cannot find any reference to that in the report.
<HR></BLOCKQUOTE>

The fact that it shows the coolant is far below maximum temp after 5 mins at maximum power.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The actual fact, as already pointed out, that this statement of the report is based on what conditions the British considered overheating. If they choosed surrealistically optimum values, the 'radiator suitability' calculated value would not give any clue about real life experience.
<HR></BLOCKQUOTE>

The British considered 135c and above overheating. It says so in the manual as well. If the coolant is lower than that, the engine isn't overheating. If it's higher, it is. The only thing surreal about it is the way you're trying to interpret something that clearly shows the coolant was nowhere near max temperature into showing it was.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>In short, we have no idea on what conditions, ie. very relevant outside temperatures the report bases it`s statements, and are left at uncretain assumptions.
<HR></BLOCKQUOTE>

In short, the report shows that at what the British considered "standard atmosphere summer temperature" the cooling system was 1.36 times minimum, with minimum being coolant reaching maximum permissible temperature.

If it was less than minimum, the engine would overheat, if it was above minimum, it would not. It was 1.36 times minimum.

There are none so blind as those that will not see.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Sorry it would be the same then as soon you changed the outside temperature, the ability of the radiator will change and you won`t get the same results anymore - the higher the outside temperature will be, the higher the exit temps from the rads shall be as well, and the radiator suitability value will decrease. You assume the enter/exit temperatures will be the same, really they won`t be.
<HR></BLOCKQUOTE>

No, I'm not assuming that at all. As air temperature increases, so will coolant temperature, although not necessarily at the same rate.

The thing is, the test found the suitability as 1.36, so any changes we make on the right side of the equation, we still have to come back to 1.36, because that's what the test found.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>As alrady pointed it, it`s not neccesarilily always the engine temp, but it has a great deal to do with it. There`s also engine load, which the main bearing and other pieces won`t support for long without breaking.<HR></BLOCKQUOTE>

Engine load is not more likely to break an engine if run for 10 5 min periods or 1 50 min period.

More from the P-51 manual extract Pyro posted:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>How the time at high power is accumulated is of secondary importance; i.e., it is no worse from the standpoint of engine wear to operate at Take-off Power for one hour straight than it is to operate in twelve 5-minute stretches, provided engine temperatures and pressures are within limits. In fact, the former procedure may even be preferable, as it eliminates temperature cycles which also promote engine wear. Thus if flight conditions occasionally require exceeding time limits, this should not cause concern so long as constant effort is made to keep the over-all time at Take-off Power to the minimum practicable. <HR></BLOCKQUOTE>

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Regardless Hop, we still don`t having the 'worst' conditions as you state. As per the climbing trials of JL 165 with closed rads, even from SL to 11 400 ft it took only about 2.39 mins to reach that high, above which the boost fell of, ie. the plane was no longer developing maximum power or heat above that height. And that`s slightly less than HALF of the 5 minutes the Merlin 66 was allowed to run at maximum power...
<HR></BLOCKQUOTE>

Which is still true in IL2. The differences from Robban's test are worse. Obviously it's possible to imagine worse conditions, you could run 25 lbs boost over Libya when the temperature is over 40c with one radiator malfunctioning. I'm not talking about the worst possible conditions for a test, but the areas in which the real life test was different from Robban's, ie it was done with rads closed, Robban's was on auto, it was done at 25 lbs, Robban's at 18 lbs, it was done under tropical conditions, Robban's in temperate conditions.

Indeed, the tests Robban did were on the Crimea map, which from what I understand from Oleg closely represents standard atmosphere, not even standard summer atmosphere.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Stating that the Spit IX should not overheat at all after 5 minutes at max power because it did not overheat after half that time in a climb is rather streching it, don`t you think ?
<HR></BLOCKQUOTE>

It didn't overheat for 5 mins at true maximum power in level flight, either.

If you can show me a way where it's possible for the Spit to climb for 5 mins at maximum power without the altitude rising and the boost pressure dropping, I'll gladly revise my statement. But Robban asked if his test should have resulted in an overheat because he climbed at maximum power, and the answer is no it shouldn't, because the real life plane climbed at maximum power under worse condtitions and didn't overheat.

Of course there are ways to overheat the Spit, you could for instance run the engine at high power on the ground with the brakes on, which would overheat pretty quickly.

You might be able to overheat in a tight turn at max power, because airflow will be limited and altitude and boost will not be dropping. It depends what your airspeed is in the turn.

There are no doubt numerous ways you could overheat a Spit IX, but maximum power in level flight or maximum power climbs in temperate conditions, with rads closed, aren't ways to overheat a Spit IX.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>ot really. Using 25 lbs boost required modifications on the Merlin 66, it was not the same engine as the ones that run on +18 lbs.
<HR></BLOCKQUOTE>

Nope, no engine mods. The boost guage had to be changed, the throttle gate, the supercharger gear change switch, new springs for the aneroid. But no engine changes.

A change in the altitude at which FS supercharger gear can be engaged is not a change in the engine.

p1ngu666
05-30-2004, 10:33 AM
theres the c/w stuff btw
basicaly its a way to find out how effective a cooling product is regardless of ambient temp http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

http://overclockers.com/articles373/
theres a okish explaination here
assuming a good enuff c/w of the spits rads, it would never overheat http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif
u bang on about how draggy they are, maybe they are actully good at losing heat and hence the drag is overcome by the extra power u can have http://ubbxforums.ubi.com/images/smiley/16x16_smiley-tongue.gif

http://www.pingu666.modded.me.uk/mysig3.jpg
&lt;123_GWood_JG123&gt; NO SPAM!

kubanloewe
05-30-2004, 02:29 PM
7 min to over 7000m for a spit IX is a bit to good I think.

also it´s ability to hold 700kmh and more in 8000m and more; think it´s more an XIV because of it´s worser turnrate http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif The TA152 is a bit faster but it cant hold it´s speed up because still overheating !

http://home.arcor.de/kubanskiloewe/g14gutspruchsig.jpg
"Finde den Feind und schiesse ihn ab alles andere ist Unsinn"
Rittmeister Freiherr Manfred von Richthofen

kubanloewe
05-30-2004, 02:35 PM
spit IX accelerate better than P51 and TA152 in high altitudes and in dives it can follow a 109.

But the heightmodell in AEP is so bad that an special Highfighter with long wings like the TA152 flies so heavy in 9000m and is stalling very fast at any maneuver except rollinghttp://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif The IX instead flies like a fish in water, lol

http://home.arcor.de/kubanskiloewe/g14gutspruchsig.jpg
"Finde den Feind und schiesse ihn ab alles andere ist Unsinn"
Rittmeister Freiherr Manfred von Richthofen

SkyChimp
05-30-2004, 02:59 PM
Isegrim, Hop is absolutely correct that the 5-minutie time-limit is set to reduce wear. It really has nothing to do with overheating. That's clearly stated in the P-51D manual:

Section VII, System Operation

Engine.
User of Take-Off (Military) Power

It is often asked what the consequences will be if the 5-minute limit at Take-Off Power is exceeded. Another frequent inquiry is how long a period must be allowed after the specified time limit has elapsed until Take-Off Power can be used again. These questions are difficult to answer, since the time-limit specified does not mean that engine damage will occur if the limit is exceeded. Instead, the limit means that total operating time at high power should be kept to a reasonable minimum in the interest of prolonging engine life.

It is generally accepted that high-power operation of an engine results in increased wear and necessitates more frequent overhaul than low-power operation. However, it is apparent that a certain percentage of operating time must be at full-power. The engine manufacturer allows for this in qualification tests in which much of the running is done at Take-Off power to prove ability to withstand the resulting loads. It is established in these runs that the engine will handle sustained high power without damage. Nevertheless, it is still the aim of the manufacturer and to the best interest of the pilot to keep within reasonable values the amount of high-power time accumulated in the field. The most satisfactory method for accomplishing this is to establish time limits that will keep pilots constantly aware of the desire to hold high-power periods to the shortest period that the flight plane will allow, so that total accumulated and resulting wear can be kept to a minimum. How the high power is accumulated is of secondary importance; ie, it is no worse from the standpoint of engine wear to operate at Take-Off Power for one hour straight than it is to operate in twelve 5-minute stretches, provided engine temperatures and pressures are within normal limits. In fact, the former procedure may even be preferable, as it eliminates temperature cycles that promote engine wear. Thus, if flight conditions occasionally require exceeding time limits, this should not cause concern so long as constant effort is made to keep overall time at Take-Off Power to the minimum practicable.

Regards,
http://members.cox.net/us.fighters/dauntless.jpg

p1ngu666
05-30-2004, 04:21 PM
spit was lighter than p51? hence better accel
spit also had the best high speed aerodynamics http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

http://www.pingu666.modded.me.uk/mysig3.jpg
&lt;123_GWood_JG123&gt; NO SPAM!

dadada1
05-31-2004, 12:28 AM
If Mk IX performs as well as this in game as in real life, why did they ever produce the Griffon Spits ? 437mph for the Mk IX HF without laminar flow wing, thats P 51 terratory isn't it ?

kubanloewe
05-31-2004, 12:53 AM
I agree dadada1; yeterday we made a showbattle between P51B and spitIX in 7000-9000m; no chnace for the Pony except long dive or frontalattackhttp://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif If the Pony dives keep cool and dont follow him he always have to come uphttp://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

http://home.arcor.de/kubanskiloewe/g14gutspruchsig.jpg
"Finde den Feind und schiesse ihn ab alles andere ist Unsinn"
Rittmeister Freiherr Manfred von Richthofen

pourshot
05-31-2004, 02:50 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by dadada1:
If Mk IX performs as well as this in game as in real life, why did they ever produce the Griffon Spits ? 437mph for the Mk IX HF without laminar flow wing, thats P 51 terratory isn't it ?<HR></BLOCKQUOTE>

Becuase the in the words of Jeffery Quill,

"the good big one will all ways beat the good little one"

http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

http://members.optusnet.com.au/~andycarroll68/mybaby.jpeg.JPG
Ride It Like Ya Stole It