PDA

View Full Version : Jet engine temps too High



Charos
05-24-2004, 01:18 AM
Firstly, I Cant comment on the YP80 as I have not spent any time in that machine and I do not have ANY data as a reference for it - perhaps this Issue applies to it as well.

Firstly lets look at the HE162:

Reference: German Jet Engine and Gas Turbine Developement 1930-1945 By Antony L. Kay

Page114: "Although the Temperature in the exhaust nozzle reached about 600 Deg
Celsius"

Page115: "By thus avoiding overheating , an Exhaust nozzle temperature limitation of between 540 and 620 Deg Celsius was to be Maintained".

Page:115: "Accelation from 6500RPM to full speed of 9500RPM took between five and seven seconds, Overspeeding on a quick accelaration mounted to about 150RPM.

Page115: "Main fuel from the tanks passed via a filter on the turbojet engine to the Barmag fuel pump, which delivered it to the all-speed governor, fuel regulator and the 16 Burner cones, The full rmp capacity of the pump was about 2,275 litres (501 Gallons per hour) at 70Kg/ sq cm (996 psi) pressure and was close to the Engine requirements at sea level on a cold day"

Reference: World war 2 Fighting Jets By Jeffrey Ethell and Alfred Price

Extract from Royal Navy's chief test pilot at Farnborough, Leutenant-Commander Eric Brown on his Evaluation of the HE162 - Which relates to flight characteristics Just after Takeoff.

Page 162: "........With the Aircraft cleaned up, I eased the Throttle back to the Recommended 9200RPM and stabilised the Climbing speed at 215MPH. The HE162 Proven very stable in the climb and reached 5000ft in 1.5 Minutes, at which I levelled out and gently brough the throttle back to 8900RPM with an Engine temperature of 450 Deg Celsius."


MY NOTES: In IL2 The engine seems accelerate a little too fast. The Auto governor should take from 5 to 7 seconds as stated above to reach full throttle from 6500RPM this assists in keeping the Engine cool as dumping too much fuel in the chamber can create up to 200 Deg Celcius of extra exhaust heat and as stated above, overreving it.
MY NOTES: Regarding Eric Brown detail's: From his figures and the Graph for "performance of the HE162 on Page 32 of Monogram Closeup 11 Volksjager, Which shows for an Altitude of 5000ft the TOP Speed at 9500RPM (with the Engine exhaust necelle set to the H Position for Hoizontal flying) a maximum speed of 340MPH is attainable.
So for Eric to obtain 300MPH at 5000ft with 8900RPM is totally to be expected.

What is interesting is the Fact that he mentions 450Deg Celsius for engine temperature.

I just simulated Browns conditions with 100% Fuel on Berlin Map at 8:00AM, Flaps at takeoff setting:

Results: Aircraft slowly given throttle to 6500RPM then Quickly to 100% and While Releasing Breaks - At 100% Power Fuel pumps were giving 100/Kg/sq cm which is 30Kg/sq cm too much.
Aircraft acceleration on Concrete runway too high - Managed to take off in approx under 500M (Assuming IL2 Runways are Approx 1000M long) should be around 850M Takeoff run

Nose wheel up and Liftoff were spot on as was 1.5Mins to get to 1500M (5000ft).

At 8900RPM at 5000ft I managed to obtain approx 700 IAS and jetpipe Exhaust temperature was just a Smidge over 550 Degrees Celsius ( Keep in Mind the difference in speed is due to different Jetpipe settings not included in IL2)

Under full power on takeoff the Jetpipe Exhaust Temperature went beyond 700 Degrees Celsius (approx 720) at 350Km/Hr not long after lift off, which is too High.



Now lets look at the ME262:


References:

Reference: German Jet Engine and Gas Turbine Developement 1930-1945 By Antony L. Kay

Both Engines from an Arado234 were recovered and sent back to Britain for Evaluation early 1945, both arrived in Pyestock on 2 March 1945.

Page: 92 "Each was burned on the Upper side, mainly around the Gearbox and auxiliaries and each was damaged by the penetration of 0.5-inch bullets. Engine 1163 was completely overhauled and first ran at Pyestock on 4 of April.Running time in that month being 9Hrs 31Mins.
.........engine 1163 gave a thrust of 1,850lb, a specific fuel consumption of 1.40and a jet temperature of 660 Degrees Celsius all at 8,800RPM on the test bed."


Pilot Notes on Engine run up
Page85: "As from 6000RPM, gently move throttle lever to Fully open. Max revs 8,700 + 200. Gas temperature must remain steady after 1 Minute"


Reference: ME262 A1 Pilots Handbook By F.D.Van Wart 1st Lt Air Corps. 15 July 1946

Section 3 Flight Operating Data : Exhaust Gas Temperature MAXIMUM 650 Degrees Celsius
Operating Condition Take off 8700 +/- 200RPM Maximum 5 Minutes



My Note: I think we can assume this was at Sea level atmospheric conditions simulating a static aircraft on the Runway as the English took their Jet Engines to Germany after the War as the Germans had High Altitude test chambers that could simulate aircraft speed up to 1000km/h.

For the ME262 winding the Engine to 7000RPM, releasing breaks and going to full Power was standard takeoff procedure Which should NOT get gas temps over 650 Degrees Celsius.

In IL2 Doing the above on Berlin Map at 8AM on Concrete Runway, Flaps at Takeoff manages to get Exhaust gas to over 800 Degrees Celsius at 230Km/h at takeoff speed.

All references state that 800Degrees Celsius is absolute maximum the Engine is rated at and at that temp things should be expected to fly apart.



Conclusion:

IL2 German Jets (possibly the YP80 as well) Exhaust Gas Temperature is NOT Correct it appears to me modeled too High.

HE162 Fuel Pressure is Too High at 100Kg/sq cm it should he 70Kg/sq cm the Me262 appears to be correct.


If anyone else can throw some more info into the Mix it would be Much appreciated.

[This message was edited by Charos on Mon May 24 2004 at 02:50 AM.]

Charos
05-24-2004, 01:18 AM
Firstly, I Cant comment on the YP80 as I have not spent any time in that machine and I do not have ANY data as a reference for it - perhaps this Issue applies to it as well.

Firstly lets look at the HE162:

Reference: German Jet Engine and Gas Turbine Developement 1930-1945 By Antony L. Kay

Page114: "Although the Temperature in the exhaust nozzle reached about 600 Deg
Celsius"

Page115: "By thus avoiding overheating , an Exhaust nozzle temperature limitation of between 540 and 620 Deg Celsius was to be Maintained".

Page:115: "Accelation from 6500RPM to full speed of 9500RPM took between five and seven seconds, Overspeeding on a quick accelaration mounted to about 150RPM.

Page115: "Main fuel from the tanks passed via a filter on the turbojet engine to the Barmag fuel pump, which delivered it to the all-speed governor, fuel regulator and the 16 Burner cones, The full rmp capacity of the pump was about 2,275 litres (501 Gallons per hour) at 70Kg/ sq cm (996 psi) pressure and was close to the Engine requirements at sea level on a cold day"

Reference: World war 2 Fighting Jets By Jeffrey Ethell and Alfred Price

Extract from Royal Navy's chief test pilot at Farnborough, Leutenant-Commander Eric Brown on his Evaluation of the HE162 - Which relates to flight characteristics Just after Takeoff.

Page 162: "........With the Aircraft cleaned up, I eased the Throttle back to the Recommended 9200RPM and stabilised the Climbing speed at 215MPH. The HE162 Proven very stable in the climb and reached 5000ft in 1.5 Minutes, at which I levelled out and gently brough the throttle back to 8900RPM with an Engine temperature of 450 Deg Celsius."


MY NOTES: In IL2 The engine seems accelerate a little too fast. The Auto governor should take from 5 to 7 seconds as stated above to reach full throttle from 6500RPM this assists in keeping the Engine cool as dumping too much fuel in the chamber can create up to 200 Deg Celcius of extra exhaust heat and as stated above, overreving it.
MY NOTES: Regarding Eric Brown detail's: From his figures and the Graph for "performance of the HE162 on Page 32 of Monogram Closeup 11 Volksjager, Which shows for an Altitude of 5000ft the TOP Speed at 9500RPM (with the Engine exhaust necelle set to the H Position for Hoizontal flying) a maximum speed of 340MPH is attainable.
So for Eric to obtain 300MPH at 5000ft with 8900RPM is totally to be expected.

What is interesting is the Fact that he mentions 450Deg Celsius for engine temperature.

I just simulated Browns conditions with 100% Fuel on Berlin Map at 8:00AM, Flaps at takeoff setting:

Results: Aircraft slowly given throttle to 6500RPM then Quickly to 100% and While Releasing Breaks - At 100% Power Fuel pumps were giving 100/Kg/sq cm which is 30Kg/sq cm too much.
Aircraft acceleration on Concrete runway too high - Managed to take off in approx under 500M (Assuming IL2 Runways are Approx 1000M long) should be around 850M Takeoff run

Nose wheel up and Liftoff were spot on as was 1.5Mins to get to 1500M (5000ft).

At 8900RPM at 5000ft I managed to obtain approx 700 IAS and jetpipe Exhaust temperature was just a Smidge over 550 Degrees Celsius ( Keep in Mind the difference in speed is due to different Jetpipe settings not included in IL2)

Under full power on takeoff the Jetpipe Exhaust Temperature went beyond 700 Degrees Celsius (approx 720) at 350Km/Hr not long after lift off, which is too High.



Now lets look at the ME262:


References:

Reference: German Jet Engine and Gas Turbine Developement 1930-1945 By Antony L. Kay

Both Engines from an Arado234 were recovered and sent back to Britain for Evaluation early 1945, both arrived in Pyestock on 2 March 1945.

Page: 92 "Each was burned on the Upper side, mainly around the Gearbox and auxiliaries and each was damaged by the penetration of 0.5-inch bullets. Engine 1163 was completely overhauled and first ran at Pyestock on 4 of April.Running time in that month being 9Hrs 31Mins.
.........engine 1163 gave a thrust of 1,850lb, a specific fuel consumption of 1.40and a jet temperature of 660 Degrees Celsius all at 8,800RPM on the test bed."


Pilot Notes on Engine run up
Page85: "As from 6000RPM, gently move throttle lever to Fully open. Max revs 8,700 + 200. Gas temperature must remain steady after 1 Minute"


Reference: ME262 A1 Pilots Handbook By F.D.Van Wart 1st Lt Air Corps. 15 July 1946

Section 3 Flight Operating Data : Exhaust Gas Temperature MAXIMUM 650 Degrees Celsius
Operating Condition Take off 8700 +/- 200RPM Maximum 5 Minutes



My Note: I think we can assume this was at Sea level atmospheric conditions simulating a static aircraft on the Runway as the English took their Jet Engines to Germany after the War as the Germans had High Altitude test chambers that could simulate aircraft speed up to 1000km/h.

For the ME262 winding the Engine to 7000RPM, releasing breaks and going to full Power was standard takeoff procedure Which should NOT get gas temps over 650 Degrees Celsius.

In IL2 Doing the above on Berlin Map at 8AM on Concrete Runway, Flaps at Takeoff manages to get Exhaust gas to over 800 Degrees Celsius at 230Km/h at takeoff speed.

All references state that 800Degrees Celsius is absolute maximum the Engine is rated at and at that temp things should be expected to fly apart.



Conclusion:

IL2 German Jets (possibly the YP80 as well) Exhaust Gas Temperature is NOT Correct it appears to me modeled too High.

HE162 Fuel Pressure is Too High at 100Kg/sq cm it should he 70Kg/sq cm the Me262 appears to be correct.


If anyone else can throw some more info into the Mix it would be Much appreciated.

[This message was edited by Charos on Mon May 24 2004 at 02:50 AM.]

Charos
05-24-2004, 03:23 AM
Finally got the Post completed - Enjoy.

BlitzPig_DDT
05-24-2004, 07:15 AM
Interesting post.

I do wonder how much this really matters though. Depending on how Oleg tied it together, it's a strong possibility that things like fuel pressure and temperature are just eye candy, with "overheat" being determined other ways.

So long as the aircraft performs as it should, and overheats at roughly the right throttle settings at roughly the right speed in roughly the right amount of time........ what difference does it make, really?

I understand wanting everything perfect. I do too. But, to be honest, I get nervous of the idea of Oleg tweaking on the code anymore. Seems to lead to radical and often ridiculous swings for no apparent reason. I'm not sure that this is enough justification to take such a risk. lol

Besides which, getting the ASI in the LW jets fixed is more important I'd think anyway. http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

http://operationcarepackage.org/ddtsig.gif

darkhorizon11
05-24-2004, 05:58 PM
Hmmm its interesting. Still though is it pertinent to the actual performance of the aircraft?

Also did you check up on the conditions that were in existance when those tests were made?

I don't think FB takes non-standard atmosphere and temperature into considerations anyways...