Hello Paul !

Found on the net :

/(See attached file: X4v2_testing_update_nov_11_2007.pdf)/

This is not a Wankel, or not even a rotary, but it is a new aircraft engine.

What seems to be quite sure, is the poor mass to power ratio of the
prototype 1.9 kg/kW (or 3.15 lbs/HP)
Even if the future production engine is lighter, it will still be 67%
heavier than the readily available 85 hp Jabiru engine for only 8% more
power...
A standard car engine plus a PSRU would do better, for much less money !

On the other hand, on their site, they claim very high fuel efficiency
(Up to 35%) but I cannot figure out if their arguments are sensible.
(If I am not mislead by my poor english, on standard cranked piston
engines, much energy would be lost through the chamber walls in the
first 45 degrees after top dead center, as the piston velocity would be
too slow)

What puzzles me, is that this argument is exactly the opposite of the
one used to justify the claimed fuel efficiency of the Bourke's engine...
And in a thin but extended high pressure volume of a Wankel, the heat
losses would be even much worse...

On top of that, they claim a very flat torque curve.
It is no use for an aviation engine connected to a propeller : Its not
the torque at low rev's but the power at continuous rev's that is
transformed in thrust at a given airspeed !

Does that make sense or not ?

Thanks

Philippe

Well said Philippe.
New engine designs surface about once a month. Some times it is hard to tell if
the purveyors are sincere or just want to sell worthless paper with stock shares
printed on it. Torque has this cachet about it. Most people hold it in high
regard. The truth is vehicles travel on HP and not torque. Torque at the prop
or the driving wheels can be anything you want it to be by gearing.
Gear boxes are always required. Gear boxes do not require billions of
dollars to develop. The gear boxes, now available, shift gears manually
in only a few thousands of a second. That removes the need for high torque engines.

Lower fuel burn is a worth while goal. I see nothing in this engine that
will result in any lower fuel burn let alone 35% lower fuel burn.

When unrealistic claims like that are made, with out recovering some of
the 50% lost in the exhaust, I become skeptical. I then suspect a stock
scam to sell some worthless paper.

Paul Lamar


Hi Paul,
You are right. There is nothing for nothing in this world.
Torque is only a calculation of horsepower and used to explain the max
horse power per RPM and efficiency of the engine described.
Regards Don

BTW Don, Has the  Detroit Diesel DD15 turbo compound engine filtered
down to the boat business yet. Of course it is only 450 HP or so.
http://www.detroitdiesel.com/engines/DD15/
From an overall point of view is it cost effective for a boat?

Paul Lamar curious.