Paul, Rotary APU for the M1 Tank:

 http://www.patpower.com/research/

 Jeff

 Wow! Thanks Jeff.

 I knew about this engine years ago but I did not know it
 made it into the Abrams M1 tank.

 It is based on the Norton and one of the few rotaries
 that will run on jet A which the tank gas turbine uses.
 Here are some pictures taken by me at some tech gathering
 years ago.

 ---------------------------------------------

 If you look at the animation very carefully you can see what looks
 like a NACA scoop shaped depression in the rotor face.

 This could be a major breakthrough in the BSFC of the rotary.
 Worth a try in the Mazda gasoline version.
 I think a steel plate can be screwed down in the current
 rotor face depression with this configuration.
 Just to try it out. A plate could also be brazed in.
 The volume of the new depression must be carefully calculated
 so as to not change the current RX8 compression ratio.

 This may also be what Mazda is using in the high efficiency
 fourth coming 16X.

 Paul Lamar



 with the good numbers for this little engine why not build a big one
 to power the tank with and double its range!
 Bill Jepson


 You mean like this one.


 Paul Lamar


    There's a video with some numbers available
    at:

    http://www.engineeringtv.com/video/TARDEC-Auxiliary-Power-Unit-for

    For the multi-fuel aspect, the patent is available at:
    http://www.freepatentsonline.com/6125813.pdf

    It consists of a pre-combustion chamber and no spark plugs (only a glow
    plug to assist in starting) - in keeping with KISS (Keep it simple
    stupid)

    Regards,
    Chandra

    Thanks Chandra.
    The insulated pre chamber is/was a clever feature.

    I think the glow plug is always on to allow heavy fuel ignition
    with only a 10:1 compression ratio. Not enough heat at only 10:1
    to one for true diesel operation. Wankel SuperTech has revised
    the geometry to increase the compression ratio.

    The Wankel Gmbh heavy fuel engine used a spark plug and apparently
    no pre chamber. Results were not that good in terms of power per cubic
    inch of displacement or BSFC. It was 25 HP down compared to the
    75 HP gasoline version. Mistral found the same problem on their heavy
    fuel version of the Mazda engine.

    This APU has 10Kw (13 HP) alternator net output. Given 80%
    efficiency for
    the alternator, the engine itself is putting out only 16 HP.
    A Norton engine of that size would be putting out 50 HP
    on gasoline. I have no idea what RPM it is running.

    Diesel fuel weight per gallon is 7.3 pounds.
    BSFC is therefore .456 or about what we are seeing
    for the Mazda engine on gasoline. Not bad.

    220 pounds with alternator.

    A turbo compound version of this engine with a water cooled e-shaft
    might be highly doable due to the low temperature of the diesel fuel
    exhaust. Easier on the turbine.

    BTW looking at the FEA in the animation I can see why both
    Mazda and SuperTech went to a narrower rotor geometry.
    The wide rotor Norton geometry used on this engine
    does not appear to be as favorable.

    I used to think that was an easier way to enlarge the 13B
    displacement but I was apparently wrong given the direction
    of both the narrow rotor Mazda 16x and WankelSuperTech.

    Obviously the Wankel is still in its infancy despite
    the fact Mazda is now claiming higher efficiency than
    the piston engine.

    Paul Lamar

Hello Paul,

If you look at the Mazda patent application filed Oct 2008, #20090101103
(http://www.freepatentsonline.com/y2009/0101103.html),apparently the
ratio for L/b (Length of rotor flank/breadth) should be at least 2.4, so
yes thinner rotors are better - for the Wankel, anyway.

Chandra

Yes I have that patent.
Thanks for sending it again. I did not get a chance to study it much yet.
I'll have to study that patent for awhile. Lots of stuff in there.
Rather amazing that Mazda did such a a comprehensive study
on the width/length ratio.

Seems amazing WankelSuperTech came up with a similar conclusion
nearly at the same time. I wonder if this patent is
delaying WankelSuperTech engine production.

There are some drawbacks to narrow rotors due to the pressure
on the rotor bearings limiting the RPM.

Perhaps Mazda needs to study 4 spark plugs in a rectangular
pattern with a much wider rotor.

I suggested something like this in 1998 but I had
no idea it would affect flame propagation speed and that
flame progation speed had so much to do with efficiency.
http://www.rotaryeng.net/ignit.gif

I called it Fires of Hell. It had six surface mount spark plugs.
Perhaps I need to start filing for patents again :)

As I said, the Wankel is still in its infancy.

Paul Lamar