Rotary oil pulsator,DR1

28 August 2003, 11:34 AM

Generally accepted all rotary engines of the era had oil pulsators. If the DR1 had one also, any clue as to its location in the cockpit? Oil tank was on the right, needed to be visable to the pilot and accessible to shut off if damaged.Also out of the way of control column and rudder bar and compass.
Where it was ?

StephenLawson · 29 August 2003, 03:53 PM

Interesting question. Flight publications wasn't real specific either. Hazarding a guess how about above the fuel pressure hand pump?

30 August 2003, 03:53 AM

Thanks for suggestion Stephen, but I don't think the
DR1 had a hand fuel pressure pump either. I think
it was gravity fed only. I'm thinking the pulsator, if present at all, might have been on the right below the emergency gas shut off rod and forward of the compass. Have made the pulsator, but don't know where to put it !

pspiranha · 31 August 2003, 06:21 AM

This is the best I can come up with. Admittedly it's a photo of a reproduction, But I understand that it's very faithfully done.

Regards,

David Johnson

31 August 2003, 08:25 AM

Great photo David
Logically, that seems the most useful position
It also had to be in a position not photographed
in an original.
Hugh

Dan_San_Abbott · 31 August 2003, 09:30 AM

Hugh Robinson:
In all my study of the Fok.DR.I, I have never seen a oil pulsator in any photo. I have studied the Peter Grosz and Ed Ferko collections photographs of the Fok.Dr.I and none revealed an oil pulsator. As twitchy as a Fok.DR.I was to fly, I don't think you would have the time to count pulses. Is it essential to the operation of a rotary engined aircraft? I don't think it is.
Blue skies,
Dan-San

31 August 2003, 09:50 AM

Mr. Abbott
I agree with everything you say. I too have looked and looked with no result. Certainly, pilots were able to fly this machine without a pulsator, but from the frequency of blued cylinder heads, you would think Mr. Fokker would have caught on quicker. No doubt it was cheaper to make them without pulsators. Guess I will throw my home made pulsator in the drawer with all the other
mistakes.
Thanks
Hugh

Dan_San_Abbott · 31 August 2003, 10:42 AM

Hugh Robinson:
Can you imagine staring at the pulsator for 10 or fifteen seconds counting the pulses while flying a Fok.DR.I. I was told by Javier Arango, " It is unstable in all three axis and you fly it from the time that you start to roll on take-off to when you stop rolling after landing, It requires you constant attention!" I think that is why Anthony Fokker a very good pilot left it off. Just something else to worry about.
Blue skies,
Dan-San

Boz0 · 31 August 2003, 01:33 PM

Hi hugh,

I think that the normal use of an oil pulsator is not always clearly undertood. Of course in some early engine, by counting the number of pulsations, one could calculate the engine rpm. But the ratio is different for each engine type and off course the rpm. A lot to remember in flight !!!
In an aircraft like the DR I, with an rpm indicator,
the use of this instrument is more simple. The pilot can see in a glance ( by seeing a pulsation ) that his engine is properly oil fed (a rotary will not run very long with no lubrification ) So it is a very important instrument, the equivalent of an oil pressure in a non rotary engine.

Regards

Alain

Langdon · 1 September 2003, 03:03 AM

Hello Hugh,

I have studied Dr.I photos for many years whilst I was preparing plans to build one, as you know my project has now changed to a D.VIII because of the late build of my motor but I have never seen one of these instruments in any photo including that of the wreckage of 591/17 (I have seen altimeters and clocks), whilst this is far from conclusive proof as interior photos are scarce I think we can say that if this instrument was fitted it would have to be placed very close to the floor, at least on that aircraft anyway.

The very good cockpit photos of the V.7 do not show a pulsator fitted so I do not believe they were fitted on the Dr.I. After the war the US Government purchased two D.VIII aircraft for evaluation, from photographic evidence it seems these aircraft carried extra instrumentation as they are the only examples fitted with airspeed indicators on their wings, as you will see in the poor quality photo below there was a pulsator fitted imediately in front of the fuel regulating lever. Certainly if you intend using your Oberursel you would have to fit this instrument whether it was originally fitted to 425/17 or not. I suggest you place it in the position it is on the McCook D.VIII.

Langdon