- May 21, 2006
- Columbia, SC
- Air Command Tandem w/ Arrow 100hp; GyroBee w/ Hirth 65hp; Air Command Tandem w/ Yamaha 150hp
- Total Flight Time
Here is my take on it!
I had an rx 1 snowmobile it turned 11000 rpm and had a gear reduction to make the clutch turn 8000 built into the engine.
It would scream and go like hell on a road or river but was next to helpless in deep snow.
At part throttle like around 8000 rpm it felt more like 40 horse.
You had to get it up to the crazy high rpm before it would work.
If you seen deep snow ahead and pinned it it could not get the rpm up quick enough
The internal reduction is 1.19:1, and at 11,000 RPM the countershaft turns the primary clutch sheave 9,244 RPM - not 8,000.
At 8000 engine RPM (ERPM) the YG4 makes 125 HP in ideal atmospheric conditions. I can personally vouch for the accuracy of the chart, below. I ran a 110 HP Arrow engine and never got the (very) draggy Air Command over 75mph at full throttle, while the YG4 at 8000 has seen 80 MPH sustained IAS, straight/level, on numerous occasions. The reliable power of the YG3 and YG4 engines is inarguable.
It is no secret that the RX1 is/was a heavy sled and that other sleds (read 2-cycle) perform better in deep powder. If you are running deep powder in an RX1 often, you probably would do well to change the clutch settings and/or springs to engage at a more advantageous ERPM, and perhaps change the chain drive gears as well.
As for me, "we" typically try to take off and land on previously cleared runways, and avoid deep powder. Come to think of it, there is no deep powder in Savannah - and I am the only guy in Georgia with a snowmobile!