what engines are making successful aero engine conversions?

On May 16, 4:13 pm, bildan wrote:
Re. PSRU's

There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. I have two in my Jeep Grand Cherokee
'airport car' transmission that have lasted 300,000 miles - so far.
These things are built to very tight tolerances and are VERY tough.

If you want still tougher, speed shops sell replacement planetaries
that can handle 1500HP or more. Ask one to handle only 100HP and
they should last forever. You can specify just about any reduction
ratio you want.

All you have to do is machine a nose case from billet aluminum to hold
the planetary gearset and the thrust bearing.

I wish it was so simple. Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run
smoothly, and at some resonant RPM the gears can die. They need almost
zero lash, or some heavy flywheel on the engine, or the damping of a
torque converter.

Dan

On May 16, 4:34*pm, wrote:
On May 16, 4:13 pm, bildan wrote:

Re. PSRU's

There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. *I have two in my Jeep Grand Cherokee
'airport car' transmission that have lasted 300,000 miles - so far.
These things are built to very tight tolerances and are VERY tough.

If you want still tougher, speed shops sell replacement planetaries
that can handle 1500HP or more. *Ask *one to handle only 100HP and
they should last forever. *You can specify just about any reduction
ratio you want.

All you have to do is machine a nose case from billet aluminum to hold
the planetary gearset and the thrust bearing.

* *I wish it was so simple. Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run
smoothly, and at some resonant RPM the gears can die. They need almost
zero lash, or some heavy flywheel on the engine, or the damping of a
torque converter.

Dan

I didn't suggest that no flywheel would be necessary but it also
depends on the number of cylinders. A 4-cyl will need a heavy one but
an 8 cylinder could do with less.

bildan wrote:
....
Re. PSRU's
There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. ...
*
*
... Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run
smoothly, and at some resonant RPM the gears can die....
Dan

... it also depends on the number of cylinders.
A 4-cyl will need a heavy one but an 8 cylinder could do with less.

Car engines often feature a crank damper on the front end.
This stops the angular oscillations that lead to crack ups.
Manual transmissions feature sprung drive on the live clutch plate.
This can serve a similar purpose. Besides the fluid flywheel there is
also the rubber spider drive to the half shaft, on some sports coupes.

As an odd-ball thought, wouldn't it be nice if two tubes sized to fit a
fabric reinforced hose pipe between them, and epoxied to both tubes
were arranged with a gap in the inner steel tube, then a gap in the
outer tube alternately - arranged to provide angular give in 'series'
for a soft, vibration absorbing drive shaft....

Brian W

On May 16, 5:26*pm, Brian Whatcott wrote:

Car engines often feature a crank damper on the front end.
This stops the angular oscillations that lead to crack ups.

The damper is to stop the crank's "ringing", not to absorb power
pulses. If the crank gets to vibrating at certain frequencies it
usually breaks.

Manual transmissions feature sprung drive on the live clutch plate.
This can serve a similar purpose. Besides the fluid flywheel there is
also the rubber spider drive to the half shaft, on some sports coupes.

The clutch's springs are supplemented by the torque-pulse-absorbing
abilities of the quill shaft, drive shaft, and axle shafts. Most of
those aren't present in a redrive.


As an odd-ball thought, wouldn't it be nice if two tubes sized to fit a
fabric reinforced hose pipe between them, and epoxied to both tubes
were arranged with a gap in the inner steel tube, then a gap in the
outer tube alternately - arranged to provide angular give in 'series'
for a soft, vibration absorbing *drive shaft....

I've done that, on electric motors. It doesn't last very long.
There is too little arm involved. As the rubber flexes, it heats up
and delaminates from the fabric. Blows up like the flat tire on a
semi.

Dan

wrote:

On May 16, 4:13 pm, bildan wrote:
Re. PSRU's

There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. I have two in my Jeep Grand Cherokee
'airport car' transmission that have lasted 300,000 miles - so far.
These things are built to very tight tolerances and are VERY tough.

If you want still tougher, speed shops sell replacement planetaries
that can handle 1500HP or more. Ask one to handle only 100HP and
they should last forever. You can specify just about any reduction
ratio you want.

All you have to do is machine a nose case from billet aluminum to hold
the planetary gearset and the thrust bearing.

I wish it was so simple. Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run
smoothly, and at some resonant RPM the gears can die. They need almost
zero lash, or some heavy flywheel on the engine, or the damping of a
torque converter.

Dan

I'm not sure that we can handle someone who knows what he is talking about, Dan.
Isn't this group about speculation and WAGs.

Seriously, Tracy Crook and others have done a lot of work on the planetary gear
redrive in conjunction with the Wankel rotary, which BTW is a much better
solution to the overall search for the optimal aircraft engine. Their
conclusions are similar to the ones you pointed to.

On May 18, 7:44*am, routund wrote:
wrote:
On May 16, 4:13 pm, bildan wrote:
Re. PSRU's

There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. *I have two in my Jeep Grand Cherokee
'airport car' transmission that have lasted 300,000 miles - so far.
These things are built to very tight tolerances and are VERY tough.

If you want still tougher, speed shops sell replacement planetaries
that can handle 1500HP or more. *Ask *one to handle only 100HP and
they should last forever. *You can specify just about any reduction
ratio you want.

All you have to do is machine a nose case from billet aluminum to hold
the planetary gearset and the thrust bearing.

* I wish it was so simple. Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run
smoothly, and at some resonant RPM the gears can die. They need almost
zero lash, or some heavy flywheel on the engine, or the damping of a
torque converter.

Dan

I'm not sure that we can handle someone who knows what he is talking about, Dan.
Isn't this group about speculation and WAGs.

Seriously, Tracy Crook and others have done a lot of work on the planetary gear
redrive in conjunction with the Wankel rotary, which BTW is a much better
solution to the overall search for the optimal aircraft engine. *Their
conclusions are similar to the ones you pointed to.

I hear rumors of a Japanese motorcycle maker that will introduce a
500cc inline 4 with direct injection. If it lives up to its Japanese
reputation, it will produce about 50 very reliable HP.

Take 5 of these 4-cyl blocks and arrange them around a common case and
crank to make a 20 cylinder, 250HP liquid cooled radial. De-rate it
to 150HP for reliability. Since it uses direct injection, the
plumbing would be air in and exhaust out. Fuel lines would be 3mm
stainless tubing from a common rail to the cylinder heads.

20 cylinders would make the engine smooth enough that the crank itself
would be plenty of flywheel. (Ever see a flywheel on a geared
radial?) A planetary in the nose case would get the prop RPM down
below 2000 RPM.

BTW, I don't think casting has any place in prototyping. Design the
parts with SolidWorks, email the file to a CNC shop who will mill them
from billet and ship the parts in a week. Machined billet parts are
FAR better than castings - and cheaper.

"bildan" wrote in message
...
On May 18, 7:44 am, routund wrote:
wrote:
conclusions are similar to the ones you pointed to.


BTW, I don't think casting has any place in prototyping. Design the
parts with SolidWorks, email the file to a CNC shop who will mill them
from billet and ship the parts in a week. Machined billet parts are
FAR better than castings - and cheaper.

I like your idea. I'm looking at a new transmission, possibly planetary,
for my helicopter. The SolidWorks software is a bit expensive for just
prototyping a single item. Do you have any idea how to get this done
without having to layout a bunch of $ for SolidWorks? Your idea is good
because the cast aluminum transmission I would be replacing was done in some
guy's mother's garage and checking for flaws was not done. I've already
found serious flaws in other castings provided with the helicopter kit.

Stu Fields



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The message was checked by ESET NOD32 Antivirus.

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"Stuart Fields" wrote in message
...

"bildan" wrote in message
...
On May 18, 7:44 am, routund wrote:
wrote:
conclusions are similar to the ones you pointed to.


BTW, I don't think casting has any place in prototyping. Design the
parts with SolidWorks, email the file to a CNC shop who will mill them
from billet and ship the parts in a week. Machined billet parts are
FAR better than castings - and cheaper.

I like your idea. I'm looking at a new transmission, possibly planetary,
for my helicopter. The SolidWorks software is a bit expensive for just
prototyping a single item. Do you have any idea how to get this done
without having to layout a bunch of $ for SolidWorks? Your idea is good
because the cast aluminum transmission I would be replacing was done in
some guy's mother's garage and checking for flaws was not done. I've
already found serious flaws in other castings provided with the helicopter
kit.


Stu,

Draw it with anything, even pencil, and pay to have someone draw it in 3D.
Software and the skill to use it is like tooling itself. Unless you intend
to do more than one project, you can have it done for much less than you
will invest doing it yourself.

But I do agree about machining from billet. Unless you plan to produce in
quantity, castings of this complexity are a waste.

On May 19, 11:25*am, "Tim" wrote:
"Stuart Fields" wrote in message

...





"bildan" wrote in message
....
On May 18, 7:44 am, routund wrote:
wrote:
conclusions are similar to the ones you pointed to.

BTW, I don't think casting has any place in prototyping. *Design the
parts with SolidWorks, email the file to a CNC shop who will mill them
from billet and ship the parts in a week. *Machined billet parts are
FAR better than castings - and cheaper.

I like your idea. *I'm looking at a new transmission, possibly planetary,
for my helicopter. *The SolidWorks software is a bit expensive for just
prototyping a single item. *Do you have any idea how to get this done
without having to layout a bunch of $ for SolidWorks? *Your idea is good
because the cast aluminum transmission I would be replacing was done in
some guy's mother's garage and checking for flaws was not done. *I've
already found serious flaws in other castings provided with the helicopter
kit.

Stu,

Draw it with anything, even pencil, and pay to have someone draw it in 3D..
Software and the skill to use it is like tooling itself. Unless you intend
to do more than one project, you can have it done for much less than you
will invest doing it yourself.

But I do agree about machining from billet. Unless you plan to produce in
quantity, castings of this complexity are a waste.

Tim, Stu,

I just mentioned SolidWorks because it's popular. Any 3D CAD software
will work fine and the files will be accepted be almost any CNC shop.

That said, it's a good idea to learn something like Autosketch or
Autocad lite if you're going to build ANYTHING. There's a little bit
of a learning curve but you'll never stop using it. Doing your own
drawings is a great opportunity to catch errors in the design before
they get expensive.

By making your own 2D CAD drawings, you can email them to 3D CAD shops
for the finish work.

On May 18, 6:44*am, routund wrote:
wrote:
On May 16, 4:13 pm, bildan wrote:
Re. PSRU's

There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. *I have two in my Jeep Grand Cherokee
'airport car' transmission that have lasted 300,000 miles - so far.
These things are built to very tight tolerances and are VERY tough.

If you want still tougher, speed shops sell replacement planetaries
that can handle 1500HP or more. *Ask *one to handle only 100HP and
they should last forever. *You can specify just about any reduction
ratio you want.

All you have to do is machine a nose case from billet aluminum to hold
the planetary gearset and the thrust bearing.

* I wish it was so simple. Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run


Seriously, Tracy Crook and others have done a lot of work on the planetary gear
redrive in conjunction with the Wankel rotary, which BTW is a much better
solution to the overall search for the optimal aircraft engine. *Their
conclusions are similar to the ones you pointed to.

One of Tracy's non-intuitive conclusions was that zero lash was NOT
necessary, and that increasing lash reduced the natural frequency of
the system. Increase the lash enough, and the "rattle" is below idle
speed. Tracy DOES use a rubber damping element on the drive side of
his units.
http://www.rotaryaviation.com/psru_development.htm

================================================== =

Tracy's units are based on the Ford C-6 truck transmission, and are
too heavy for a 40 - 60 HP engine. How about something lighter? I
propose we take a look at the Toyota A131L, which was in production
FOREVER
Applications:
* 1984-2002 Toyota Corolla (1.6L 4A-FE / 3 spd.) (includes FX)
* 1985–1988 Chevrolet Nova
* 1990-1992 geo prizm
Another possible choice would be the A40
Applications:
* Carina 1600 rwd 08/75-04/84
* Carina 1800 rwd 04/81-04/84
* Celica 2000 rwd 01/78-07/82
* Corolla 1300 03/80-09/83
* Corona liftback 04/79-03/81
* Cressida 12/77-06/81
* Cressida 2000 05/81-09/82
* Crown 2600 05/77-03/80
* Starlet 1300 02/82-02/85
or the 245E
Applications:* 1993-2007 Corolla 1.8L 7A-FE