Jump to content

Engine shut off at high altitude


TBear
 Share

Recommended Posts

I noticed that, with external enviroment at a temperature around 7° Celsius and barometic pressure of 29.90, when i climb and reach about 18.000 feet the engine shuts off. Can someone tell me why...what I'm doing wrong?

Link to comment
Share on other sites

I noticed that, with external enviroment at a temperature around 7° Celsius and barometic pressure of 29.90, when i climb and reach about 18.000 feet the engine shuts off. Can someone tell me why...what I'm doing wrong?

 

From Page 80 of the Spitfire Manual:

 

"In order to prevent fuel boiling at high altitudes in warm weather conditions, the fuel system is equipped with a fuel tank pressurizer system that switches on automatically at altitudes above 20000 feet. An aneroid valve feeds air, pressurized by a vacuum pump, into the fuel tanks. Pressurizing, however, impairs the self-sealing of the tanks and should be turned on only when the fuel pressure warning lamp lights up. In very warm weather at very high altitudes a rich cut may occur with the tanks pressurized, and pressure must then be turned off. The pressurizing cock is on the starboard side of the cockpit immediately below the instrument panel. The default position of the pressurizer system is OFF, and must be turned ON only when a red warning light signalizes that the fuel pressure has dropped below 10ft/in2. The control unit for the fuel pressurizer system is located under the right side of the instrument dashboard. The valve for disabling fuel tank pressurization installed in the ventilation line of the fuel tanks allows for immediate disabling of fuel tank pressure in case of damage to the pipelines or fuel tanks, as the defensive properties of the lower tank suffer in case of excess pressure. The valve is located in the right wing fairing, and the control unit is located to the right and below the pilot’s seat. A hand wobble pump is mounted on the starboard side of the cockpit of early aircraft powered by a Merlin 66 engine. The pump draws its supply from the fuselage lower tank and delivers into the main fuel supply line at a point between the main fuel cock and the non-return valve. Designed to fill the aircraft's supply pipeline, drive pump and the carburetor before starting the engine. It can also be used as an emergency pump in case of drive pump failure. After exhausting the aircraft's external tanks, when switching to the main tank, it is necessary to pump gasoline into the engine by means of the manual pump until stable motor operation. A hand wobble pump, installed in the starboard side of the cabin behind the indentificator light control switch, can be used to draw fuel from the bottom tank. A Ki-gass type priming pump used to to fill the engine cylinders and fuel lines with fuel before engine startup is located on the right side of the fuselage frame № 8. Gas from the bottom of lower tank flows through a line into the motor's suction nozzles under pressure created by the pump. A Bendix-Stromberg injection type carburetor, in contrast to float-feed type carburetors, provides an uninterrupted supply of fuel into the engine while under negative Gs and while performing intense maneuvers. Electric gasoline gauge, one sensor piece mounted in the lower tank. The gauge and power button are mounted at the bottom right of the instrument panel. The gauge measures the amount of petrol in the tank, but only when the button is pressed. The indicator has two scales: the lower scale is used for measuring gasoline while in flight, and the upper scale for use on the ground (when the aircraft is in its tricycle position. A warning lamp is installed next to the gasoline gauge and is triggered when fuel pump pressure falls below 10 lb/in2. The lamp is powered by a circuit switch on the throttle quadrant. "


Edited by jcomm

Flight Simulation is the Virtual Materialization of a Dream...

Link to comment
Share on other sites

I noticed that, with external enviroment at a temperature around 7° Celsius and barometic pressure of 29.90, when i climb and reach about 18.000 feet the engine shuts off. Can someone tell me why...what I'm doing wrong?

 

If you're going too slow, the engine water will overheat and the engine will shut off (with smoke). Maintain 180 mph throughout the climb.

 

..

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

So Jcomm, what u operatively do when U ear engine "coughing" when reaching the critical altitude? The problem seem due to LOW temperature.

 

for Holbeach..the engine is not broken, infact when i reach an altitude below 14000 ft its enough to psh starter button to light it up again...

Link to comment
Share on other sites

I regularly fly from T/O to 40,000', full throttle, full revs, without touching anything and it never misses a beat, so try that @ 180 mph and see what happens.

 

Supercharger will kick into 2nd gear at 14,000'.

 

..


Edited by Holbeach

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

Precisely. Turn it on after starting the engine, and turn it off after landing, before taxiing - according to the manual.

 

Can't see that in the DCS manual, got a page number?

 

All I see is the explicit instructions before take off that it must be off in the red box on Page 23 of the Quick Start. No matching instruction in the full manual.

 

As an aside, I know it's merely been lost in translation, but it's midly confusing when the manual says "fuel boost valve" when it's actually referring to the "fuel pressure boost valve" in all instances, and the actual booster pump is the "electric booster pump" with no mention of fuel.

Link to comment
Share on other sites

We've established in another thread https://forums.eagle.ru/showthread.php?t=179160 that early Merlin 66-engined Mk IXs had no electric fuel boost pumps, just a wobble pump. Slightly later Mk IXs had both, and eventually the wobble pump was dropped in favour of just the boost pump. If we accept that having the boost pump switched ON is necessary in the sim to get to higher altitudes , this begs the question how did the early Mk IXs manage it, without this mod? Or did they? Can anyone shed any light on this? I don't think we can discount the possibility that what we're seeing here is a bug.

Link to comment
Share on other sites

We've established in another thread https://forums.eagle.ru/showthread.php?t=179160 that early Merlin 66-engined Mk IXs had no electric fuel boost pumps, just a wobble pump. Slightly later Mk IXs had both, and eventually the wobble pump was dropped in favour of just the boost pump. If we accept that having the boost pump switched ON is necessary in the sim to get to higher altitudes , this begs the question how did the early Mk IXs manage it, without this mod? Or did they? Can anyone shed any light on this? I don't think we can discount the possibility that what we're seeing here is a bug.

 

The early Mk IX had a different carb (SU). The Bendix has the boost pump, which is required to maintain fuel press. in the system and is switched on at pre T/O checks

There is no mention, in the RL manual, of the fact that the engine is incapable of running on the engine pump above 18000' or what to do if it fails above that height, or if it should run at all with it switched off.

 

Edit: The pump is required to prevent aeration in the fuel lines with the Bendix, so we must assume this occurs above 18000'.

 

You can also run at high alt. with the pump off and the press cock on.

pump on, cock on, pump fails, engine runs.

pump on, cock off, pump fails engine stops, no restart until below 18000'.

..


Edited by Holbeach

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

The early Mk IX had a different carb (SU). The Bendix has the boost pump, which is required to maintain fuel press. in the system and is switched on at pre T/O checks

There is no mention, in the RL manual, of the fact that the engine is incapable of running on the engine pump above 18000' or what to do if it fails above that height, or if it should run at all with it switched off.

 

Edit: The pump is required to prevent aeration in the fuel lines with the Bendix, so we must assume this occurs above 18000'.

 

You can also run at high alt. with the pump off and the press cock on.

pump on, cock on, pump fails, engine runs.

pump on, cock off, pump fails engine stops, no restart until below 18000'.

..

Thanks Holbeach, but I'm still unconvinced.

 

The main features distinguishing the variants of the Spitfire IX, XI and XVI are outlined in Part I (Descriptive) para 1 of the RL manual. It stipulates that the while the F IX had a Merlin 61, 63 or 63A engine, the LF IX had the Merlin 66 engine. It goes on to note that "Merlin 61 and 63 engines have S.U. float-type carburetors, but on Merlin 66, 70 and 266 engines these are replaced by Bendix-Stromberg injection carburetors."

 

Figure 4 (Fuel System Diagram) at the back of the RL manual illustrates two configurations for the Merlin 66 and 70 engines, one with just the wobble pump (described as "early Merlin 66 and 70 engines") and one with only the electric boost pump (later 66 and 70). Our DCS version falls between these and has both pumps. A note at the foot of the drawing advises that Merlin 61 and 63 engines are not fitted with boost or wobble pumps.

 

Based on all this and the earlier investigation of wobble vs boost pump, I'm inclined to conclude that:

 

a. all LF IX had the Merlin 66 engine;

b. all Merlin 66 engines had the Bendix-Stromberg carburetors;

c. early LF IX had the wobble pump only, "transitional" LF IX had both wobble and electric boost pumps, later LF IX had the boost pump only;

d. it is very unlikely that the early LF IX (which had no boost pump) would be altitude restricted in the way our DCS model currently is, when the electric boost pump is not switched ON (I can't picture the RW pilot frantically working the wobble pump in order to climb to altitude); and

e. therefore, we have a bug. The engine should not be suffering fuel starvation at altitude just because the electric boost pump has mistakenly been left OFF.

Link to comment
Share on other sites

- Pressurize fuel with electric pump takes only 2/3 seconds (PN say 30s).

 

- Start engine requires only 2x pump in Ki-Gass (in 20C or 0C map weather).

 

- Can start engine, taxi, take-off with propeller pitch in back position, throttle increase RPM as if that "automatic system" mentioned in PN has fitted - just don't reduce the RPM.

Link to comment
Share on other sites

So what have we got.

 

On our Merlin 66 we have a Bendix, with electric pump, which must be kept on at all times (RL manual).

 

OAT at 0 C at start.

Water max 60 the engine cut out at 15600' with pump off, press. off and at

22500' pump off, press. on.

These numbers varied with different power settings.

No restart without pump. No restart with wobble.

 

What we have is aeration pressure loss under any condition, rather than just high temps at altitude. So if the elec. pump failed at say 25000', the engine would cut and there's no way to restart until decent to 16000'.

What happens IRL, I have no idea, but the engine pump and tank pressure system seem unable to cope at high altitude.

..

 

Purely academic of course, but it kept me busy.

 

..

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

I believe the answer is that there were two pumps, see the attachment...

 

We have:

 

item No.5 which is fuel pump 1 found on all IX

 

item No.15 the wobble pump found on early/mid IX

 

Item No.19 shown but not listed is actually the fuel pump added to mid/late IX

_20161228_142323.thumb.JPG.155d4927d767b2a39e675c136bfab601.JPG

Windows 10 Pro | ASUS RANGER VIII | i5 6600K @ 4.6GHz| MSI RTX 2060 SUPER | 32GB RAM | Corsair H100i | Corsair Carbide 540 | HP Reverb G2 | MFG crosswind Pedals | Custom Spitfire Cockpit

Project IX Cockpit

Link to comment
Share on other sites

The electric pump was added to pressurize the fuel line and prevent aeration in the line.

 

The question is How did the early MkIX get to high altitude on its engine pump, when ours can't get past 16000' with pump only and 22500 with pump and tank pressure?

I flew it at 0 C to rule out aeration from warm weather.

 

..

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

22500? I nursed mine up to Angels 39.

Took a long time though.

OS:Win10 Home CPU:i7 3770K 3.5(@4.3GHz) COOLER:ZalmanCNPS10X-PERFORMA MOBO:GigabyteGA-Z77X-UD5H SSD#1:SamsungEVO850Pro 500GB SSD#2:SanDisk240GB HDD:2x Seagate2TB GFX:GigabyteGTX670 WF3 2GB OC1058MHz RAM:16GB 16000MHz DDR3 KEYB'Ds:Corsair K95/MS SidewinderX4 MOUSE:LogitechG700s MON:2x ASUS 24” ROUTER:ASUS RT-N66U DarkKnight INTERWEBS:Fibre152Mbps/12Mbps JOYSTICK:TM T16000m Modded THROTTLE:TM TWCS HEADTRACK:TrackIR5Pro

Link to comment
Share on other sites

I did a couple of quick trials last night, just using the Free Flight IA mission. Start conditions for this are 6500 feet altitude, 3000 rpm, fuel tank pressurization OFF and boost pump ON. In both cases I immediately switched the boost pump OFF, set boost to 12 psi, reduced rpm to 2850 and commenced climb at 180 mph. While climbing I adjusted throttle and climb angle as needed to keep boost at 12 psi and maintain 180 mph for as long as possible. No problems were seen with overheating, and overall, the results were not quite as bad as expected.

 

First attempt, reached approx. 16,500 feet before the engine began to run roughly. The low fuel pressure light was not illuminated. Leveled off and switched fuel tank pressurization ON. Engine began to run smoothly again within 30-45 seconds. Resumed climb. At approx. 37,000 feet low fuel pressure light came on and engine cut out entirely. Lowered the nose and attempted restart. No success, all the way down to 10,000 feet, at which point I switched the boost pump ON and the engine immediately roared back to life. Called it a day and went to the Mess for a beer.

 

Second attempt, switched fuel tank pressurization ON at the start of the climb. No problem seen until approx. 38,000 feet, at which point the low fuel pressure light came on and the engine died. Switched the boost pump ON and the engine immediately came back to life. Resumed climb, eventually coaxing it up to 41,000 feet, very briefly. Even flying straight and level is a challenge up there. Thought I deserved another virtual beer after that.

 

I'm left questioning a couple of things concerning the initial engine problem at approx. 16,500 feet (first attempt, with tank pressurization and boost pump both OFF). First, why no low fuel pressure light? Second, is it realistic that we not even get to 20,000 feet w/o fuel delivery problems?

 

If anyone out there has the time and inclination, it would be good to get confirmation that what I saw is repeatable.


Edited by blue_six
typo, 16,500
Link to comment
Share on other sites

22500? I nursed mine up to Angels 39.

Took a long time though.

 

16,500, with engine pump only.

 

22,500, with engine pump and tank pressure.

 

43,414, with engine pump, tank pressure and electric boost pump.

 

(but things have changed since I did those tests).


Edited by Holbeach

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

I did a couple of quick trials last night, just using the Free Flight IA mission. Start conditions for this are 6500 feet altitude, 3000 rpm, fuel tank pressurization OFF and boost pump ON. In both cases I immediately switched the boost pump OFF, set boost to 12 psi, reduced rpm to 2850 and commenced climb at 180 mph. While climbing I adjusted throttle and climb angle as needed to keep boost at 12 psi and maintain 180 mph for as long as possible. No problems were seen with overheating, and overall, the results were not quite as bad as expected.

 

First attempt, reached approx. 16,500 feet before the engine began to run roughly. The low fuel pressure light was not illuminated. Leveled off and switched fuel tank pressurization ON. Engine began to run smoothly again within 30-45 seconds. Resumed climb. At approx. 37,000 feet low fuel pressure light came on and engine cut out entirely. Lowered the nose and attempted restart. No success, all the way down to 10,000 feet, at which point I switched the boost pump ON and the engine immediately roared back to life. Called it a day and went to the Mess for a beer.

 

Second attempt, switched fuel tank pressurization ON at the start of the climb. No problem seen until approx. 38,000 feet, at which point the low fuel pressure light came on and the engine died. Switched the boost pump ON and the engine immediately came back to life. Resumed climb, eventually coaxing it up to 41,000 feet, very briefly. Even flying straight and level is a challenge up there. Thought I deserved another virtual beer after that.

 

I'm left questioning a couple of things concerning the initial engine problem at approx. 16,500 feet (first attempt, with tank pressurization and boost pump both OFF). First, why no low fuel pressure light? Second, is it realistic that we not even get to 20,000 feet w/o fuel delivery problems?

 

If anyone out there has the time and inclination, it would be good to get confirmation that what I saw is repeatable.

 

More or less the same as you, so this just leaves the question.

 

Why can't the pump supplied by RR with their engine, get past about 18,ooo'?

 

A simple hole in the tank or pump failure would stop the engine when flying at even medium altitudes.

 

..

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

More or less the same as you, so this just leaves the question.

 

Why can't the pump supplied by RR with their engine, get past about 18,ooo'?

 

A simple hole in the tank or pump failure would stop the engine when flying at even medium altitudes.

 

..

 

The fuel tanks were pressurized to prevent vapour lock: as blue_six discovered, entering a climb with tank pressurization off led to his fuel boiling and developing vapour lock, which doesn't necessarily register as low fuel pressure.

 

From FAA Regulations: Chapter 14: Aircraft Fuel System:

 

Vapor lock is a condition in which AVGAS vaporizes in the fuel line or other components between the fuel tank and the carburetor. This typically occurs on warm days on aircraft with engine-driven fuel pumps that suck fuel from the tank(s). Vapor lock can be caused by excessively hot fuel, low pressure, or excessive turbulence of the fuel traveling through the fuel system. In each case, liquid fuel vaporizes prematurely and blocks the flow of liquid fuel to the carburetor.

 

Aircraft gasoline is refined to have a vapor pressure be between 5.5 pounds per square inch (psi) and 7.0 psi at 100 °F. At this pressure, an aircraft fuel system is designed to deliver liquid fuel to the carburetor when drawn out of the tank by an engine-driven fuel pump. But temperatures in the fuel system can exceed 100 °F under the engine cowl on a hot day. Fuel may vaporize before it reaches the carburetor, especially if it is drawn up a line under a low pressure, or if it swirls while navigating a sharp bend in the tubing. To make matters worse, when an aircraft climbs rapidly, the pressure on the fuel in the tank decreases while the fuel is still warm. This causes an increase in fuel vaporization that can also lead to vapor lock. Various steps can be taken to prevent vapor lock. The use of boost pumps located in the fuel tank that force pressurized liquid fuel to the engine is most common.

 

Once blue_six pressurized the fuel tank, the fuel began to settle down, but the condensing fuel had more than likely left water in the system, that began to form ice crystals at high altitude. Result = low fuel pressure and an embarrassing silence...

 

As fuel vaporizes, it draws energy from its surroundings to change state from a liquid to a vapor. This can be a problem if water is present. When fuel vaporizes in the carburetor, water in the fuel-air mixture can freeze and deposit inside the carburetor and fuel induction system. The fuel discharge nozzle, throttle valve, venturi, or simply the walls of the induction system all can develop ice. As the ice builds, it restricts the fuel-air flow and causes loss of engine power. In severe cases, the engine stops running.

 

In other words, keep your fuel tanks pressurized, and the fuel booster pump installed in the fuel tank is also there for a good reason. :smilewink:

Link to comment
Share on other sites

A bit of background to this: many early Spitfire F. Mk IXs with Merlin 61s were fitted with an automatic tank pressurizing valve, plus a fuel cooler fitted in the port wing root. From the Spitfire IX (Merlin 61) Pilot's Notes, August 1942:

 

Paragraph 6:

Supermarine%20Spitfire%20%20IX%20%20Pilots%20Notes%20A.P1565J%20194312_zpsqqyuwgbt.jpg

Supermarine%20Spitfire%20%20IX%20%20Pilots%20Notes%20A.P1565J%20194313_zpspuuiajmr.jpg

 

Spitfire%20%20IX%20PNs75_zpsflhtaxox.jpg

Spitfire%20%20IX%20%20PNs76_zpsq0t7qory.jpg

Supermarine%20Spitfire%20%20IX%20%20Pilots%20Notes%20A.P1565J%20194386_zps2kdweabv.jpg

 

With the Merlin 66 and its Stromberg Injector carburettor, the fuel pressure was increased from c. 8-10 lbs/sq. in. to 14-16 lbs/sq. in. plus the fuel system was modified on all but the earliest L.F. Mk. IXs* to include the booster pump in the lower fuel tank.

 

*This means those L.F Mk IXs that were built by Supermarine from February 1943, in the EN529-EN637 range http://www.airhistory.org.uk/spitfire/p036.html range.

 

The mass production of L.F Mk. IXs started at Castle Bromwich in July 1943, in the MH3xx range http://www.airhistory.org.uk/spitfire/p063.html - in the interim, priority had been given to building the L.F. Mk. VIII w/Merlin66.

  • Like 1
Link to comment
Share on other sites

Good research.

 

I think that covers my question.

 

..

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..





..

Link to comment
Share on other sites

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...