Any idea how this was done ?
Blipping was actually achieved by firing all the cylinders, but only after a set number of revolutions of the engine (depending on the switch position).
The normal sequence of cylinders ignition for 7cyl rotaries (such as the Gnome 50 and 80HP) was 1-3-5-7-2-4-6. For 9 cylinders rotaries (such as the Gnome Monosoupape 100HP, Le Rhone 9C 80HP and 9J 110HP) the sequence was 1-3-5-7-9-2-4-6-8 (On the first revolution 1-3-5-7-9, then on the second revolution 2-4-6-8).
On the 100HP monosoupape, the blip caused each cylinder to be fired only once per three engine revolutions but the engine remained in perfect balance.
The 160hp Gnome 9N offered more possibilities. It had a dual option in regards to its blip switch. Depending of which magneto you were running off of. With the selection of one magneto you were either full power or off, while the selection of the second magneto gave the pilot a choice of 1/2, 1/4 , 1/8 power or off.
You could be set to fire all 9, 7, 5, or just 3 cylinders on each revolution. The cylinders that were not firing still cycled, but had no spark. They filled with fuel/oil and then expelled it, unburnt, into the cowl.
There were five positions on the switch: 4-3-2-1-0, 4 being full power.
Normal firing order (9 cylinders rotary) was: 1-3-5-7-9-2-4-6-8, meaning two revolutions of the engine to fire all plugs, 0 being off.
On switch position 3 every other ignition pulse was skipped, so the firing order was 1-5-9-4-8-3-7-2-6 and it took four revolutions instead or two for all cylinders to fire, meaning half speed.
On position 2 it took eight revolutions to fire all cylinders, 1 (skip 3-5-7)-9 (skip 2-4-6)-8, and so on, meaning 1/4 speed.
On position 1 it brought 1/8 speed, taking 16 revolutions to complete the firing order
You had to be careful, because blipping too long would "strangle" the engine, and an airborne restart of the engine was not always possible. As well you would not blip it too long in the air while the propeller was turning the engine under influence of the air flow, because, if the cylinders would be flooded too long without firing, a prolonged re-igniting would set the whole engine afire - or the engine would not start again because of wet spark plugs.
"double de-clutching"
How many times have I heard, as a kid, my father repeat how good it was that cars have no longer need for that! He learned to drive, while he was soldiering in ww2, on an obsolete pre-war British (?) truck that had the steering wheel in the middle, and demanded "double de-clutching" - as in was mainly on mountain roads, it was sometimes quite "an experience and an experiment as well".
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Topic: Krasnyi Vostock - Orient is Red (Read 43639 times)
