A beautiful Me109 pump

[schwarze-man]

Hi Tony,
By fuel-boost pump I guess you mean the fuel tank pumps, or fuel booster pumps? The answer is that Daimler Benz specified the engine to have a quite comprehensive suite of ancillaries. Messerschmitt had to pare these to the bone to fit the 109. On the 109 the fuel supply comes from the fuel tank in two paths. One is a low pressure immersed electrical pump in the tank and the other a simple direct pipe from the bottom of the tank. The immersed pump (booster pump) is used normally for start-up or, if fuel pressure problems occurr in flight. Both fuel delivery lines passed forward under the cockpit to two shut-off cocks, one for each line. The shut-of cock on the line from the simple direct feed from the tank incorporates a manual hand pump that can be operated by the ground crew for start if the battery is flat. From the two shut-off cocks, the two fuel delivery lines run forwards on the RHS to the Kraftstoff forderpumpe or, the engine backing pump, referred to before. This Forderpumpe provides the constant pressure (1.3-1.8 kg/cm2), variable flow that the fuel injection pump requires. The fuel is metered and pumped to the fuel injectors by the fuel injection pump elements at about 12 kg/cm2 in individual pulses, much the same as a mechanical diesel pump.

SM

[Broncazonk]

Originally Posted by schwarze-man

Hi Tony,
By fuel-boost pump I guess you mean the fuel tank pumps, or fuel booster pumps? The answer is that Daimler Benz specified the engine to have a quite comprehensive suite of ancillaries. Messerschmitt had to pare these to the bone to fit the 109. On the 109 the fuel supply comes from the fuel tank in two paths. One is a low pressure immersed electrical pump in the tank and the other a simple direct pipe from the bottom of the tank. The immersed pump (booster pump) is used normally for start-up or, if fuel pressure problems occurr in flight. Both fuel delivery lines passed forward under the cockpit to two shut-off cocks, one for each line. The shut-of cock on the line from the simple direct feed from the tank incorporates a manual hand pump that can be operated by the ground crew for start if the battery is flat. From the two shut-off cocks, the two fuel delivery lines run forwards on the RHS to the Kraftstoff forderpumpe or, the engine backing pump, referred to before. This Forderpumpe provides the constant pressure (1.3-1.8 kg/cm2), variable flow that the fuel injection pump requires. The fuel is metered and pumped to the fuel injectors by the fuel injection pump elements at about 12 kg/cm2 in individual pulses, much the same as a mechanical diesel pump.
SM

Schwarze-man, I just re-read all your posts in this thread, and I must say, it was a pleasure, a rare pleasure, to read them again..

Bronc

[schwarze-man]

Thank you Bronc!
I think the big German aero engines are best understood by studying the original manuals because, there is a whole load of carp written in some of the older popular printed matter about them. Unfortunately, this leaves a non-German speaker with great difficulties but, you can understand a lot if you do acquire the original manual copy's for say, the DB601/603/605 on CD/Disc from Archiv Hafner, about £50 ish. Cheers

SM

[schwarze-man]

I realised that I had referred to the starting of the Bf109 with a flat battery but, without much context and so, I will expand a little further.
The Germany produced 109 with the DB engine was always equipped with the manual-only inertia starter. This was because there was not room for the electrically activated type of starter due to the ammunition magazines and, because the aircraft had a very small capacity 24v battery. With a flat battery the engine could still be cranked for start (as usual), priming fuel fuel could be injected by the manual primer (as usual), main fuel pressure could be raised for supply to the engine pumps by the manual fuel supply pump and, the self-energising magneto was sufficient to obtain a successful start, without the "shower of sparks" HT buzzer (if the battery was totally flat). I am reminded of some other aircraft that used air supply (that you could manually charge with a pump) to the cylinders for starting. These systems may seem basic but, if you need to start an aero-engine in the middle of nowhere with just fuel, they are the difference between fly or, no fly! Cheers

SM

[Tony Kambic]

Thanks SM. Yes I was referring to Fuel Booster Pumps. And I agree your explanations are exquisite.

Is the manual pump used for when the battery was flat a wobble type? I assume it is under the cowling somewhere? Or is it accessible without opening the cowl? I know I've seen images of the cranks used to start the German engines, but I thought those were connected to the inertia starter. Would that crank also pump the fuel?

Tony

[schwarze-man]

Hi Tony! Yes, the hand crank that fits on the RHS of the engine cowling is purely for the inertia starter. Incidentally, the inertia starters were, I think, Bosch designed, under a patent from the USA "ECLIPSE" Co.
Now, the manual fuel booster pump was a simple diaphram type pump that was incorporated into the body of the suction tank feed fuel filter/shut-off cock. This pump is activated by getting under the centre section, opening the panel and pushing/pulling the linkage up and down. The fuel pressure in the lines to the fuel injection pump soon rises and is indicated on the 0-2kg/cm side of the double pressure gauge in the cockpit. NRV's maintain the pressure quite well for 30sec or so and, once the lines through to the fuel injection pump (via the Kraftstoff Forderpumpe) are pressurised by this method (or the electrical booster pump), engine start is assured. Additional priming fuel is also injected by the pilot using the cockpit primer before start. Cheers

SM

[gilles collaveri]

Hi Guys
I am really impressed by your knowledge.
The story of this pump is a mystery.
She was in a display, belonging to a French Collector in Cannes, who himself apparently had brought it back from North Africa;
This is all I know about it..
GC

[schwarze-man]

Hi Gilles,
Although I have commented on this pump as fitted to a Bf109 with the DB605A, the same pump could have been fitted to any aircraft that used the DB605A or DB605B as this was the same pump on those versions. This would also include possibilities of some versions of the Bf110 and Me210 as well as others. Unfortunately, the Fuel injection pumps were not normally stamped with the motor serial number and so, unless there is some provenance such as recovery from a known engine or an original note or referrence, it is impossible to be certain of the history of the pump. Best wishes

SM