Gnome Rotary Engine run

[PC777]

Greeting to all,

The South Australian Aviation Museum held it’s first Aero Engine run at the new location on Sunday 30th October 2006.

There were several interesting engine types on display and run for the pleasure of the large crown.

All in all a good day with perfect weather.

I thought that one of the engines might be of interest to people on this forum so I thought I would post a few photo’s of it.


Front View:


Close Up of ID plate:


Running on frame:


Close up of it running:


Here are some details about this engine from the SA Aviation Museum web site:

Country of Origin
France

Description
9 Cylinder, Single valve Rotary

Power
100 Hp

Bore
140 mm

Stroke
150 mm

Speed
1200 rpm

Weight
150 Kg

Fuel Consumption
10 gallons/hour

Oil Consumption
16 pints/hour

HISTORY

Gnome built their first Rotary engines in 1908, The model on display is a 9 cylinder, 100 Hp version, built during the first World War. Most WW1 aircraft were powered by rotaries. This type of engine powered such types as the Avro 504K, Bristol Scout D and Nieuport 28C, 1.

The rotary engine is unique in that the engine rotates with the propellor about the crankshart, which remains stationary, and is bolted to the airframe. Lubrication was achieved by adding as much as 25 to 35% of oil to the fuel mixture, since the oil had to be able to be dissolved within the fuel, vegatable (usually castor oil) was used. One result of this was that the head reach cylinder spewed fire and oil, necessitating the use of a cowling. Another consequence was that World War 1 pilots learned to have excellent bowel control.
Monosoupapes had no throttle, and control of engine speed was achieved by "blipping", turning the engine on and off, which accounts for the unique sound of a WW1 plane landing.

I will try to find out some more about the history of this particular engine and post it if anyone is interested.

Regards to all

PC

[YavorD]

Thank you PC777!
I am wondering why this Gnome runs without any form of a propeller usually needed to compensate engine torque? I assume this engine is just idling ...
Regards,
Yavor

[StephenLawson]

Originally Posted by PC777

Greeting to all,

Gnome built their first Rotary engines in 1908, The model on display is a 9 cylinder, 100 Hp version, built during the first World War. Most WW1 aircraft were powered by rotaries. This type of engine powered such types as the ... Nieuport 28C, 1...PC

Actually the Nieuport 28 used the 160hp Gnome. That aside. This is a great post and I thank you for the opportunity to see the old girl crank up.

[PC777]

Hello again,

YavorD you are quite correct, this engine is not run at anything above approximate idle.


StephenLawson I think the description is just a generalisation of information to the casual reader.

From my limited understanding and I may be wrong... but I think this is a 1912 version taken from a Seaplane of some sort, this is what I have heard I will try to find out more.

I noticed that I did not photograph the second information plate, this plate has some very interesting information on it, I will do this possibly this weekend and maybe get a few more close up shots if anyone is interested.

Regards to all

PC

[YavorD]

Originally Posted by PC777

...I may be wrong... but I think this is a 1912 version ...

I do not think Engine No.30174 can be poduced before 1914. I am guessing, but production date can be much later!

Regards,
Yavor

[Taz]

PC- This is the same engine which powered the D.H.2 and, in license built version as the Oberursel U.I, the Fokker E.III. Castor oil was chosen as a lubricant because it does not dissolve in gasoline and therefore maintained its lubricating properties when both were sprayed into the crankcase. The oil and gasoline (or Benzin for the Germans) were carried in separate tanks and never mixed.

These early Gnomes were not true single valve engines, even though they were called monosoupape, because they had exhaust valves opened and closed by the pushrods and automatic intake valves in the pistons with springs and counterweights to operate them. The later Gnome 9N which powered the Nieuport 28 and some Sopwith Camels used inlet ports similar to two stroke engines and was a true single valve engine with only pushrod operated exhaust valves.

There were actually many more inline engined aircraft built in WW-I than rotary engined aircraft. The German ratio was around 8-10:1 and I do not have numbers for the allies, but they should be similar. Just make a list in your head and you will see what I mean. D.H.2, Pup, Camel, Strutter, Snipe vs F.E.2, B.E.2, R.E.8, S.E.5a, D.H.4/9/9a. Numbers of aircraft built increased greatly in the latter part of the war and the large majority were fixed cylinder/inline. For the French, there were Breguets, Salmsons, Spads vs earlier Nieuports and handfuls of rotary Moranes and other types.

Great photos. Thanks.

Taz
Terry Phillips

[cfgray]

Hi, Taz, and All,
Actually, all of the Gnome Monosoupape engines were single valve, with ported hole-type intakes on the cylinder walls and pushrod actuated exhaust head valves, one per cylinder.
It is the Lambda, Omega, Lambda-Lambda ("Double Lambda"), and other pre-1914 Gnome "Greek letter series" engines were dual valve with "pop-up" valves in the piston heads as well as pushrod operated head valves.
This engine was probably license-built in England, not built in France, so the apparent serial number may reflect a license-prefix, rather than an actual production number - meaning that it may be license-built English Gnome Monosoupape No. 174, rather than No. 30,174.
The long "nose" would mean that it was used in an "overhung" mount, with a bearing collar ahead of the crankcase, as well as the usual rear mount.
A beautiful example, very nice to see. I hope that the key was removed from the keyway on the "nose" before the engine was run. It's probably also a really good and much safer idea to run the engine with a "stick" or "club" mounted in place of a propeller (if a propeller is unavailable), rather than to run it without anything mounted. For one thing, in addition to smoothing any kinetic harmonics, a "stick" or "club" or propeller serves to keep the rpm's down within the safety zone.
Best,
cfgray

[gipsymoth236k]

Gnome experts!

I own a 160hp Gnome 9N. Were they only French-built, or where they also built elsewhere?

Thanks for any information.

Regards, Gary Sewall

[Breguet]

Any chance of a small video? With sound?

[Breguet]

Go here for an animated cut-away drawing of how it works:

http://www.keveney.com/gnome.html