what engines are making successful aero engine conversions?

[Stealth Pilot[_2_]]

I'm in Western Australia. locally our supplies of VW engines seem to
have dried up. Even BMW motor cycle engines seem to have dried up.
what other currently available engines have been successfully used in
aircraft?

the engine problem seems to provide the most unsolvable dilema when
attempting to build a small aircraft. I'd hate to think that the
prospect of engine conversions was passing.

Stealth Pilot

[[email protected][_2_]]

On May 13, 12:40*am, Stealth Pilot >
wrote:

> the engine problem seems to provide the most unsolvable dilema when
> attempting to build a small aircraft.

I agree. It has been the main problem for the past 100
years..........

> I'd hate to think that the
> prospect of engine conversions was passing.

It's not passing, just evolving, but slowly. We just have to accept
the fact that other than for small engines (~30 hp or less) all mass
produced units will be water cooled, which complicates things for
aircraft use. I happen to be in the camp that thinks that, over all,
water cooling will prove to be an advantage. We as home builders
still have more to learn before my assertion can be proven.

In the mean time our options are somewhat limited. We either use
existing aircraft motors, convert air cooled auto engines (a
diminishing supply), or take Veedubers suggested path of converting
water cooled lowers to air cooled units.

Simple sand casting, increasing availability of CNC machining and off
the shelf parts may provide another path for the budget minded?
=========================
Leon McAtee

[[email protected]]

Dear Stealth (and the Group)

We may be looking it this the wrong 'way 'round.

There are plenty of engines which offer excellent power-to-weight
ratios. Unfortunately, they do so at rpm's which make them
impractical for slinging a prop UNLESS a PSRU is used.

A good case-in-point is the Rotax. The Rotax engine is only 1300cc
but it is designed to operate near 6000 rpm. What makes the engine
successful is the PSRU between the engine and the prop.

There are two obvious conclusions we can draw from this. The first is
that the engines themselves, despite any practical combination of cam
& cooling, are simply too small to be used with the propeller mounted
directed to the crankshaft. (This leads to another series of
questions worthy of discussion but which I will leave untouched at
this time.)

The second point is that the PSRU, which does NOT enjoy the same TBO
as the engine itself, has been designed specifically for this
application, taking advantage of the engine's torque & power curves,
and including mechanical features that make it suitable for the
mounting of a propeller; mounting the engine to an airframe and so
forth.

It may then be argued that we are wasting our time by focusing on the
ENGINE; that we should be devoting our energies to a suitable PSRU
that may be attached to a WIDE VARIETY of engines.

Having devoted most of my attention to the VW engine, I have little to
offer the Group should the discussion turn to PSRU's but it would seem
that the hand-maiden of these light-weight, powerful engines MUST be
an automotive TRANSMISSION having similar features of light-weight and
power-handling capacity. Here again, I lack the background and
experience to do more than mutter; there are aspects of PSRU's,
transmissions and torque converters about which I know nothing at
all... other than the fact they must exist (since the engines exist).

At the very least, I know the GEARS must exist.

Were I in Western Australia, rather than curse the darkness (and wish
for a Corvair to suddenly appear on my doorstep) I think I would light
a single candle by diving into whatever came my way in the form of
light-weight engines and trannies.

I suppose there has to be a clutch in there somewhere, so that means
I'm probably looking at a flywheel as well... fate stacking the weight
against my urge to fly. But perhaps some of those powerful, light-
weight engines ARE large enough to be able to drive a prop directly,
even if I had to find someone to grind me a new cam.

Liquid cooling need not be a road-block IF we begin by throwing out
the stock radiator. With ram-air of 90mph or so available for
everything other-than take-offs, a pair of heater cores may provide
enough area to keep things in the green. Plus, there is a couple of
quarts of oil that may also be pressed into service as an auxiliary
coolant.

The point of all this is that the lack of Volkswagens or other air-
cooled engines should not be taken as an automatic out. If push comes
to shove I could always convert a stray Holden, offering it up to
something like a Pietenpohl.

-R.S.Hoover

[Anthony W]

Honda makes a nice little 4 cylinder engine that is used in their
personal watercraft that I've always thought would be a good small plane
power plant but I've not been able to try it.

Tony

wrote:
> Dear Stealth (and the Group)
>
> We may be looking it this the wrong 'way 'round.
>
> There are plenty of engines which offer excellent power-to-weight
> ratios. Unfortunately, they do so at rpm's which make them
> impractical for slinging a prop UNLESS a PSRU is used.
>
> A good case-in-point is the Rotax. The Rotax engine is only 1300cc
> but it is designed to operate near 6000 rpm. What makes the engine
> successful is the PSRU between the engine and the prop.
>
> There are two obvious conclusions we can draw from this. The first is
> that the engines themselves, despite any practical combination of cam
> & cooling, are simply too small to be used with the propeller mounted
> directed to the crankshaft. (This leads to another series of
> questions worthy of discussion but which I will leave untouched at
> this time.)
>
> The second point is that the PSRU, which does NOT enjoy the same TBO
> as the engine itself, has been designed specifically for this
> application, taking advantage of the engine's torque & power curves,
> and including mechanical features that make it suitable for the
> mounting of a propeller; mounting the engine to an airframe and so
> forth.
>
> It may then be argued that we are wasting our time by focusing on the
> ENGINE; that we should be devoting our energies to a suitable PSRU
> that may be attached to a WIDE VARIETY of engines.
>
> Having devoted most of my attention to the VW engine, I have little to
> offer the Group should the discussion turn to PSRU's but it would seem
> that the hand-maiden of these light-weight, powerful engines MUST be
> an automotive TRANSMISSION having similar features of light-weight and
> power-handling capacity. Here again, I lack the background and
> experience to do more than mutter; there are aspects of PSRU's,
> transmissions and torque converters about which I know nothing at
> all... other than the fact they must exist (since the engines exist).
>
> At the very least, I know the GEARS must exist.
>
> Were I in Western Australia, rather than curse the darkness (and wish
> for a Corvair to suddenly appear on my doorstep) I think I would light
> a single candle by diving into whatever came my way in the form of
> light-weight engines and trannies.
>
> I suppose there has to be a clutch in there somewhere, so that means
> I'm probably looking at a flywheel as well... fate stacking the weight
> against my urge to fly. But perhaps some of those powerful, light-
> weight engines ARE large enough to be able to drive a prop directly,
> even if I had to find someone to grind me a new cam.
>
> Liquid cooling need not be a road-block IF we begin by throwing out
> the stock radiator. With ram-air of 90mph or so available for
> everything other-than take-offs, a pair of heater cores may provide
> enough area to keep things in the green. Plus, there is a couple of
> quarts of oil that may also be pressed into service as an auxiliary
> coolant.
>
> The point of all this is that the lack of Volkswagens or other air-
> cooled engines should not be taken as an automatic out. If push comes
> to shove I could always convert a stray Holden, offering it up to
> something like a Pietenpohl.
>
> -R.S.Hoover

[[email protected]]

On Wed, 13 May 2009 06:40:13 GMT, Stealth Pilot
> wrote:

>
>I'm in Western Australia. locally our supplies of VW engines seem to
>have dried up. Even BMW motor cycle engines seem to have dried up.
>what other currently available engines have been successfully used in
>aircraft?
>
>the engine problem seems to provide the most unsolvable dilema when
>attempting to build a small aircraft. I'd hate to think that the
>prospect of engine conversions was passing.
>
>Stealth Pilot

Why do we always assume we have to reinvent the wheel? If you need 40
hp, here it is. Even altitude compensating EFI available soon.
Designed for max continuous power. Rig a PSRU with a poly-v belt for
more efficient prop speed/length.

40 not enough, stack 2 end to end. Have a steel crank made if the iron
makes you nervous.

Not every small gas engine is a Briggs. I've run 100s of these Kohlers
for 40 years. Some 2000 hours in a year. Almost all the 30 and 40 year
old garden tractors have Kohlers or Tecumsehs. Not many Briggs.

Model Command PRO CH1000
Max Power @3600 RPM hp (kW) 40 (29.8)
Displacement cu in (cc) 61 (999)
Bore in (mm) 3.5 (90)
Stroke in (mm) 3.1 (78.5)
Peak Torque @ Maximum lbs ft (Nm) 61.5 (83.4)
Compression Ratio 8.8:1
Dry Weight lbs (kg) 132 (59)
Oil Capacity U.S. quarts (L) 2.9 (2.75)
Lubrication Full pressure w/full-flow filter
Dimensions L x W x H in 15.3 x 19.0 x 27.5

[flybynightkarmarepair]

On May 14, 2:38*pm, wrote:
> On Wed, 13 May 2009 06:40:13 GMT, Stealth Pilot
>
> > wrote:
>
> >I'm in Western Australia. locally our supplies of VW engines seem to
> >have dried up. Even BMW motor cycle engines seem to have dried up.
> >what other currently available engines have been successfully used in
> >aircraft?
>
> >the engine problem seems to provide the most unsolvable dilema when
> >attempting to build a small aircraft. I'd hate to think that the
> >prospect of engine conversions was passing.
>
> >Stealth Pilot
>
> Why do we always assume we have to reinvent the wheel? If you need 40
> hp, here it is. Even altitude compensating EFI available soon.
> Designed for max continuous power. *Rig a PSRU with a poly-v belt for
> more efficient prop speed/length.
>
> 40 not enough, stack 2 end to end. Have a steel crank made if the iron
> makes you nervous.

Neither of these ideas are exactly trivial.

> Not every small gas engine is a Briggs. I've run 100s of these Kohlers
> for 40 years. Some 2000 hours in a year. Almost all the 30 and 40 year
> old garden tractors have Kohlers or Tecumsehs. Not many Briggs.
>
> Model Command PRO CH1000
> Max Power @3600 RPM hp (kW) 40 (29.8)
> Displacement cu in (cc) 61 (999)
> Bore in (mm) 3.5 (90)
> Stroke in (mm) 3.1 (78.5)
> Peak Torque @ Maximum lbs ft (Nm) 61.5 (83.4)
> Compression Ratio 8.8:1
> Dry Weight lbs (kg) 132 (59)
> Oil Capacity U.S. quarts (L) 2.9 (2.75)
> Lubrication Full pressure w/full-flow filter
> Dimensions L x W x H in 15.3 x 19.0 x 27.5


For the benefit of our Western Australian friend, http://www.epgengines.com..au/
has a distributorship in WA.

The Generac 990 is in the same class, and is the starting point for
the Valley Engineering Big Twin Re-drive setup.
http://www.brandnewengines.com/generachorizontalv-twinengine27hp0047391-1-1-2.aspx

One of the problems is there seems to be whole in the market between
30 hp and 80-100. The two examples above are the biggest air-cooled
gasoline industrial engines commonly. There are a (very) few liguid
cooled engines in this range (Kubota and Daihatsu ), they tend to be
substanially heavier. The other problem is the way the emissions and
fuel efficiency have driven car engines to higher RPM and teeny
cylinders.

One idea is run an aluminum block car engine direct drive at low RPM.
A Honda engine of about 1.8L should be able to meet this, say an F-
Series: http://en.wikipedia.org/wiki/Honda_F_engine The later K
series engines are more complex - V-TEC, etc, and probaby are not
wanted. Engine weight should be in the mid-200 lb category. The
smaller D series might be enough, although they are not that much
lighter, say, low 200s for the bare engine. A Suzuki G- or J- Series
might also fit the bill, and since they were fitted to Utes their
torgue band might be lower, better driving a prop.

Another is to direct drive a small truck/industrial engine. Kubota
and Daihatsu make liquid cooled gas engines too small for you, and
Ford and GM make iron block 1.6L engines that are too large.

http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/industrial/2010_1600_Industrial.pdf
http://www.fordpowerproducts.com/FordPowerProducts/pdf/1.6LSpec.pdf
Nissan also makes industrial engines in this range.

Suzuki and Subaru engines have been converted, by Americans,
Canadians, Germans and Poles.

http://www.raven-rotor.com/html/specs.html
http://www.airtrikes.net/engines.shtml
http://www.aerotech-poland.com/

[Copperhead]

On May 13, 1:40*am, Stealth Pilot >
wrote:
> I'm in Western Australia. locally our supplies of VW engines seem to
> have dried up. Even BMW motor cycle engines seem to have dried up.
> what other currently available engines have been successfully used in
> aircraft?
>
> the engine problem seems to provide the most unsolvable dilema when
> attempting to build a small aircraft. I'd hate to think that the
> prospect of engine conversions was passing.
>
> Stealth Pilot

A very active group of fellows in Poland are using Moto Guzzi M/C
engines as well as BMW's. Honda marketed a similar type of engine that
has been tinkered around with a bit but most likely needs a different
crank or cam. I have read of one person using a small Honda auto
engine that he replaced the crankshaft in order to get more thrust at
lower rpm's. He didn't use a PSRU. Couldn't on of the three cylinder
Geo engines be modified with a custom crank or cam to do this with the
right prop? Water cooling has advanced a lot in the last few year's
with very light weight radiator's.

[Stealth Pilot[_2_]]

On Thu, 14 May 2009 13:34:22 -0700 (PDT), wrote:

>Dear Stealth (and the Group)
>
>We may be looking it this the wrong 'way 'round.
>
<snip>

>The point of all this is that the lack of Volkswagens or other air-
>cooled engines should not be taken as an automatic out. If push comes
>to shove I could always convert a stray Holden, offering it up to
>something like a Pietenpohl.
>
>-R.S.Hoover

hoover you are proof positive that old dogs can learn new tricks!
I note the use of the word Holden :-) and punch that upturned thumb to
the sky thinking yesss hoover you are a champion :-) :-)

this is a subject pregnant with information shall we say but in
looking at the converted aero engine, or more specifically the
dismantled VW engine on my workbench, a weighup shows that the
chankshaft is the heaviest part in the engine.
making it lighter isnt an option by which I mean making the existing
crankshaft less substantial.
so one weight reduction option is to make it shorter, which leads to
looking again at the pobjoy geared radial made back in 1934. I've
always believed that a modern technology revisit to this design would
pay dividends. at 23inches diameter and delivering 90hp it has to be a
winner.

the great bugbear of the radial of course is the increased drag of the
flat round radial engine when compared to the flat four engine or
inline engine or even v12 layout. ...so history tells us.

I read this today in Bill Gunstons book "Development of Piston Aero
Engines"...

"Nowhere was the process [of drag reduction] more effective than in
the case of radial engines, where instead of offering an ungainly
shape - called by aerodynamicists a "bluff body"- they were enclosed
in a tight cowling in such a way that overall drag was often zero,
thrust from the heated cooling air more than countering drag from
other causes."

I was gobsmacked. NO cooling drag from a tightly cowled radial engine!
(The Hawker Fury was offered as an example)
Cooling drag in a Wittman W8 Tailwind was measured by Raspet to be 10%
of total drag at speeds over 120mph (104 and a bit knots)
I've never ever heard of a flat 4 having no cooling drag.

far from being a hackneyed subject the challenge of locating or
designing and building a 40hp aero engine presents some amazingly
fertile challenges.

one of the real plusses in this quest is that your approach is totally
different from mine and yet both are totally valid paths to follow.
Remember George Graham using a mazda rotary in second gear? That was
another path. he proved the concept but the gearbox failing just
pointed to a more substantial gearbox being needed.
I suppose the real challenge is not to be enthused by the
possibilities but to get machining and put examples in the air.

we arent done yet bob.

Stealth Pilot

[[email protected]]

On May 15, 1:37*am, Stealth Pilot >
wrote:
>
> this is a subject pregnant with information shall we say but in
> looking at the converted aero engine, or more specifically the
> dismantled VW engine on my workbench, a weighup shows that the
> chankshaft is the heaviest part in the engine.
> making it lighter isnt an option by which I mean making the existing
> crankshaft less substantial.
> so one weight reduction option is to make it shorter
----------------------------------------------------------

Ummm....(picking lint from my bolly-holy) actually you CAN lighten the
VW crank by a fair amount. Take a look at the crankshaft of a real
aircraft engine. (No, closer than that...) Look at the con-rod
journals. On most engines, they are hollow. A couple of after-market
crankshaft makers here in Southern California offered such cranks.
Most of them suffered from cracks but boy would they spin! Which was
the goal. As in drag racing.

Another option is to make the con-rod journals SMALLER, as in 50mm vs
55. I know it tain't much but when every little bit helps...

Of course, the real question is WHY do you want to make it lighter?
(No, don't tell me. I'd probably just break down and cry.) Because
if you are sooper-serious about reducing the weight of the VW engine
there are a few options you apparently have not yet explored, such as
using steel tubing for the barrels. And drilling-out the rocker-arm
shafts. And the cam shaft. And throwing away that steel sump
plate... (Make a new drain by drilling & tapping an M8 hole in the
outer corner next to the hole in the sump... the one for the Type III
dip-stick & filler. Now there is no reason NOT to use an aluminum
panel for your sump plate. Indeed, you can rivet brackets to it; help
support the carb-heat box and whatever)

Your rods can stand a bit of dieting. Some guys turn them into
carefully balanced Swiss cheese, replace them every couple of races
(or risk having one snap in two).

But probably the biggest weight reduction is to put the prop on the
clutch-end of the engine, reducing your prop hub to a flange and a
spool-type spacer, the combination of which typically weighs less than
a long/thick prop-hub for the other end of the crankshaft.

Ditto for MOUNTING the engine. With the prop on the proper end of the
crankshaft you may use the existing threaded bosses on either side of
the pump opening and build yourself a space-frame type mount. No
'accessory housing'. Mount the dynamo directly to the crankcase..
itty-bitty flanged driver for the magnets.

All-aluminum intake manifolding. Single-port heads.

Trick here, another there, bottom line is on the order of 140 pounds.
Which you gotta admit is pretty light for a veedub.

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


, which leads to
> looking again at the pobjoy geared radial made back in 1934. I've
> always believed that a modern technology revisit to this design would
> pay dividends. at 23inches diameter and delivering 90hp it has to be a
> winner.
>-----------------------------------------------------------------------------

As for the shorter crankshaft weighing LESS... I think I'd have to
see it. Typical radial crank calls for a massive master-rod, bolted-
on counter weights, etc. And three jugs wouldn't get you very much. I
think you'd need five or seven before you'd start to see any
improvement in the pwr vs weight department.

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

> the great bugbear of the radial of course is the increased drag of the
> flat round radial engine when compared to the flat four engine or
> inline engine or even v12 layout. ...so history tells us.
-----------------------------------------------------------------------------------

Dig deeper. Search seed: NACA cowling. Magic!

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

> I read this today in Bill Gunstons book "Development of Piston Aero
> Engines"...
>
> "Nowhere was the process [of drag reduction] more effective than in
> the case of radial engines, where instead of offering an ungainly
> shape - called by aerodynamicists a "bluff body"- they were enclosed
> in a tight cowling in such a way that overall drag was often zero,
> thrust from the heated cooling air more than countering drag from
> other causes."
>
> I was gobsmacked. NO cooling drag from a tightly cowled radial engine!
> (The Hawker Fury was offered as an example)
> Cooling drag in a Wittman W8 Tailwind was measured by Raspet to be 10%
> of total drag at speeds over 120mph (104 and a bit knots)
> I've never ever heard of a flat 4 having no cooling drag.
>-------------------------------------------------------------------------------------------------

Me neither... if the thing is air-cooled. But zero-D IS a possibiity
with liquid cooling. Tank fulla Prestone lets you move the cooling
drag to some area where it ain't. Drag. Get the input/output ratios
right you get NEGATIVE drag... which is called Thrust. (More Magic,
as per F-51)

------------------------------------------------------------------------------------------------
> far from being a hackneyed subject the challenge of locating or
> designing and building a 40hp aero engine presents some amazingly
> fertile challenges.
>
> one of the real plusses in this quest is that your approach is totally
> different from mine and yet both are totally valid paths to follow.
> Remember George Graham using a mazda rotary in second gear? That was
> another path. he proved the concept but the gearbox failing just
> pointed to a more substantial gearbox being needed.
> I suppose the real challenge is not to be enthused by the
> possibilities but to get machining and put examples in the air.
> ----------------------------------------------------------------------

Yeah, something like that. Except you need someone to run the numbers
on the GEAR TEETH or you get these horrible screechy noises

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

> we arent done yet bob.
------------------------------------------------------------>

Heaven's no! (Swapping his scones recipe for biscuits... and finding
out they're the same thing!)

Maybe mixing up some Secret Sauce for the exhaust stack & ports that
moves the heat farther down the pipe before it begins to cool. That
maintains the VELOCITY of the exhaust gases and other noxious fumes,
allows you to move the same amount of gas in less time through a
smaller pipe, creates a deep area of low pressure in the combustion
chamber just when the poppet valve pops it... SUCKS the fuel/air
charge into the cylinder doing all sorts of nice things to the
Volumetric Efficiency along the way. Super charging without that
little turbine ...less weight, even when plumbing 1 into 3 and 2 into
4. Not a big improvement but some.

Add all the somes (sums?) and while you can't point your finger at any
single one of them an say 'Ah ha!' you get to wave your arms at the
whole engine and the DOZENS of incremental improvements -- all those
'unimportant' details the Experts are always telling us we can
ignore. Add them up and while any single ONE may be 'unimportant'
their total adds up in a remarkable fashion.

Impossible, the experts say. Like the NACA ring-cowling. (Put one on
the NYP and Charlie could have made it to Moscow with fuel to spare.)

[Orval Fairbairn[_2_]]

In article >,
Stealth Pilot > wrote:

(snip)
> so one weight reduction option is to make it shorter, which leads to
> looking again at the pobjoy geared radial made back in 1934. I've
> always believed that a modern technology revisit to this design would
> pay dividends. at 23inches diameter and delivering 90hp it has to be a
> winner.

From what I have heard, the Pobjoy was NO joy to fly! Apparently it was
highly unreliable and would quit at the least desirable times.

The Pobjoy factory was destroyed during a WW-II bombing raid (perhaps by
disgruntled RAF pilots who had flown one?).

(snip)

--
Remove _'s from email address to talk to me.

[Stealth Pilot[_2_]]

On Fri, 15 May 2009 13:26:27 -0400, Orval Fairbairn
> wrote:

>In article >,
> Stealth Pilot > wrote:
>
>(snip)
>> so one weight reduction option is to make it shorter, which leads to
>> looking again at the pobjoy geared radial made back in 1934. I've
>> always believed that a modern technology revisit to this design would
>> pay dividends. at 23inches diameter and delivering 90hp it has to be a
>> winner.
>
>From what I have heard, the Pobjoy was NO joy to fly! Apparently it was
>highly unreliable and would quit at the least desirable times.
>
>The Pobjoy factory was destroyed during a WW-II bombing raid (perhaps by
>disgruntled RAF pilots who had flown one?).
>
>(snip)

I was talking with the Shuttleworth Trust guys about their Comper
Swift and its Pobjoy. evidently it has been made from a few different
models and is a nightmare for replacement parts. they have had it
embalmed for 3 years now. they usually rest aircraft for two years at
a time in rotation but the Pobjoy is problem enough that they didnt
take it out of preservation. It leaks oil like the best of british
engines evidently.
but the design of the pobjoy has aspects that are brilliant. picture
90 hp out of a little engine 22 inches in diameter.
it has one often overlooked claim to fame in that it was the first of
the high reving geared reduction engines.

I still maintain that this engine is worthy of a manufacturing revisit
and update for the homebuilder market.

does anyone know whether any of the drawings remain for any of the
pobjoy engines? I'd like to build one.

Short Brothers in Ireland evidently bought out Pobjoy when it went
toes up but I have not been able to find out whether any of the Pobjoy
factory drawings have survived.

Stealth Pilot.

[Peter Dohm]

"Stealth Pilot" > wrote in message
...
> On Fri, 15 May 2009 13:26:27 -0400, Orval Fairbairn
> > wrote:
>
>>In article >,
>> Stealth Pilot > wrote:
>>
>>(snip)
>>> so one weight reduction option is to make it shorter, which leads to
>>> looking again at the pobjoy geared radial made back in 1934. I've
>>> always believed that a modern technology revisit to this design would
>>> pay dividends. at 23inches diameter and delivering 90hp it has to be a
>>> winner.
>>
>>From what I have heard, the Pobjoy was NO joy to fly! Apparently it was
>>highly unreliable and would quit at the least desirable times.
>>
>>The Pobjoy factory was destroyed during a WW-II bombing raid (perhaps by
>>disgruntled RAF pilots who had flown one?).
>>
>>(snip)
>
> I was talking with the Shuttleworth Trust guys about their Comper
> Swift and its Pobjoy. evidently it has been made from a few different
> models and is a nightmare for replacement parts. they have had it
> embalmed for 3 years now. they usually rest aircraft for two years at
> a time in rotation but the Pobjoy is problem enough that they didnt
> take it out of preservation. It leaks oil like the best of british
> engines evidently.
> but the design of the pobjoy has aspects that are brilliant. picture
> 90 hp out of a little engine 22 inches in diameter.
> it has one often overlooked claim to fame in that it was the first of
> the high reving geared reduction engines.
>
> I still maintain that this engine is worthy of a manufacturing revisit
> and update for the homebuilder market.
>
> does anyone know whether any of the drawings remain for any of the
> pobjoy engines? I'd like to build one.
>
> Short Brothers in Ireland evidently bought out Pobjoy when it went
> toes up but I have not been able to find out whether any of the Pobjoy
> factory drawings have survived.
>
> Stealth Pilot.
>
I have heard that the (so called) area rule has a considerable effect on
drag at surprisingly low speeds.

Presuming that is the case, the benefit of the smaller diameter engine might
be trivial, except on a single seater or a tandem two seater, so you might
also consider the Rotec radial.

Peter

[Stealth Pilot[_2_]]

On Sat, 16 May 2009 10:58:14 -0400, "Peter Dohm"
> wrote:


>>
>I have heard that the (so called) area rule has a considerable effect on
>drag at surprisingly low speeds.
>
>Presuming that is the case, the benefit of the smaller diameter engine might
>be trivial, except on a single seater or a tandem two seater, so you might
>also consider the Rotec radial.
>
>Peter
>
>

rotec is not in consideration. my target is a light 40 hp engine for
single seat aircraft.

[bildan]

On May 14, 2:34*pm, wrote:
> Dear Stealth (and the Group)
>
> We may be looking it this the wrong 'way 'round.
>
> There are plenty of engines which offer excellent power-to-weight
> ratios. *Unfortunately, they do so at rpm's which make them
> impractical for slinging a prop UNLESS a PSRU is used.
>
> A good case-in-point is the Rotax. *The Rotax engine is only 1300cc
> but it is designed to operate near 6000 rpm. *What makes the engine
> successful is the PSRU between the engine and the prop.
>
> There are two obvious conclusions we can draw from this. *The first is
> that the engines themselves, despite any practical combination of cam
> & cooling, are simply too small to be used with the propeller mounted
> directed to the crankshaft. *(This leads to another series of
> questions worthy of discussion but which I will leave untouched at
> this time.)
>
> The second point is that the PSRU, which does NOT enjoy the same TBO
> as the engine itself, has been designed specifically for this
> application, taking advantage of the engine's torque & power curves,
> and including mechanical features that make it suitable for the
> mounting of a propeller; mounting the engine to an airframe and so
> forth.
>
> It may then be argued that we are wasting our time by focusing on the
> ENGINE; that we should be devoting our energies to a suitable PSRU
> that may be attached to a WIDE VARIETY of engines.
>
> Having devoted most of my attention to the VW engine, I have little to
> offer the Group should the discussion turn to PSRU's but it would seem
> that the hand-maiden of these light-weight, powerful engines MUST be
> an automotive TRANSMISSION having similar features of light-weight and
> power-handling capacity. *Here again, I lack the background and
> experience to do more than mutter; there are aspects of PSRU's,
> transmissions and torque converters about which I know nothing at
> all... other than the fact they must exist (since the engines exist).
>
> At the very least, I know the GEARS must exist.
>
> Were I in Western Australia, rather than curse the darkness (and wish
> for a Corvair to suddenly appear on my doorstep) I think I would light
> a single candle by diving into whatever came my way in the form of
> light-weight engines and trannies.
>
> I suppose there has to be a clutch in there somewhere, so that means
> I'm probably looking at a flywheel as well... fate stacking the weight
> against my urge to fly. *But perhaps some of those powerful, light-
> weight engines ARE large enough to be able to drive a prop directly,
> even if I had to find someone to grind me a new cam.
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.

[[email protected]]

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

[Brian Whatcott]

Stealth Pilot wrote:
> On Fri, 15 May 2009 13:26:27 -0400, Orval Fairbairn
> > wrote:
>
>> In article >,
>> Stealth Pilot > wrote:
>>
>> (snip)
>>> so one weight reduction option is to make it shorter, which leads to
>>> looking again at the pobjoy geared radial made back in 1934. I've
>>> always believed that a modern technology revisit to this design would
>>> pay dividends. at 23inches diameter and delivering 90hp it has to be a
>>> winner.
>>From what I have heard, the Pobjoy was NO joy to fly! Apparently it was
>> highly unreliable and would quit at the least desirable times.
>>
>> The Pobjoy factory was destroyed during a WW-II bombing raid (perhaps by
>> disgruntled RAF pilots who had flown one?).
>>
>> (snip)
>
> I was talking with the Shuttleworth Trust guys about their Comper
> Swift and its Pobjoy. evidently it has been made from a few different
> models and is a nightmare for replacement parts. they have had it
> embalmed for 3 years now. they usually rest aircraft for two years at
> a time in rotation but the Pobjoy is problem enough that they didnt
> take it out of preservation. It leaks oil like the best of british
> engines evidently.
> but the design of the pobjoy has aspects that are brilliant. picture
> 90 hp out of a little engine 22 inches in diameter.
> it has one often overlooked claim to fame in that it was the first of
> the high reving geared reduction engines.
>
> I still maintain that this engine is worthy of a manufacturing revisit
> and update for the homebuilder market.
>
> does anyone know whether any of the drawings remain for any of the
> pobjoy engines? I'd like to build one.
>
> Short Brothers in Ireland evidently bought out Pobjoy when it went
> toes up but I have not been able to find out whether any of the Pobjoy
> factory drawings have survived.
>
> Stealth Pilot.
>

A Comper Swift flew out of Coventry (UK) in the 60s-70s time frame.
It had the unexpected attribute that it could climb almost twice as fast
as a C150 - though its top speed was nothing to write home about.
It was called "Scarlet Angel". It was the plane that had flown home from
India. I later regretted not taking up the offer to buy it when the
opportunity came along.

Brian W

[bildan]

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.

[Brian Whatcott]

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

[cavelamb himself[_5_]]

Stealth Pilot wrote:
> On Sat, 16 May 2009 10:58:14 -0400, "Peter Dohm"
> > wrote:
>
>
>> I have heard that the (so called) area rule has a considerable effect on
>> drag at surprisingly low speeds.
>>
>> Presuming that is the case, the benefit of the smaller diameter engine might
>> be trivial, except on a single seater or a tandem two seater, so you might
>> also consider the Rotec radial.
>>
>> Peter
>>
>>
>
> rotec is not in consideration. my target is a light 40 hp engine for
> single seat aircraft.

Rotax 503, although I doubt that's what you'll want...

[cavelamb himself[_5_]]

Peter Dohm wrote:
> "Stealth Pilot" > wrote in message
> ...
>> On Fri, 15 May 2009 13:26:27 -0400, Orval Fairbairn
>> > wrote:
>>
>>> In article >,
>>> Stealth Pilot > wrote:
>>>
>>> (snip)
>>>> so one weight reduction option is to make it shorter, which leads to
>>>> looking again at the pobjoy geared radial made back in 1934. I've
>>>> always believed that a modern technology revisit to this design would
>>>> pay dividends. at 23inches diameter and delivering 90hp it has to be a
>>>> winner.
>> >From what I have heard, the Pobjoy was NO joy to fly! Apparently it was
>>> highly unreliable and would quit at the least desirable times.
>>>
>>> The Pobjoy factory was destroyed during a WW-II bombing raid (perhaps by
>>> disgruntled RAF pilots who had flown one?).
>>>
>>> (snip)
>> I was talking with the Shuttleworth Trust guys about their Comper
>> Swift and its Pobjoy. evidently it has been made from a few different
>> models and is a nightmare for replacement parts. they have had it
>> embalmed for 3 years now. they usually rest aircraft for two years at
>> a time in rotation but the Pobjoy is problem enough that they didnt
>> take it out of preservation. It leaks oil like the best of british
>> engines evidently.
>> but the design of the pobjoy has aspects that are brilliant. picture
>> 90 hp out of a little engine 22 inches in diameter.
>> it has one often overlooked claim to fame in that it was the first of
>> the high reving geared reduction engines.
>>
>> I still maintain that this engine is worthy of a manufacturing revisit
>> and update for the homebuilder market.
>>
>> does anyone know whether any of the drawings remain for any of the
>> pobjoy engines? I'd like to build one.
>>
>> Short Brothers in Ireland evidently bought out Pobjoy when it went
>> toes up but I have not been able to find out whether any of the Pobjoy
>> factory drawings have survived.
>>
>> Stealth Pilot.
>>
> I have heard that the (so called) area rule has a considerable effect on
> drag at surprisingly low speeds.
>
> Presuming that is the case, the benefit of the smaller diameter engine might
> be trivial, except on a single seater or a tandem two seater, so you might
> also consider the Rotec radial.
>
> Peter
>
>
>

Interesting point, Peter.

The skinny tandem Piper Cub, for instance, has much higher equevilant
flat plate area than a fat side by side Taylorcraft.

[Bob]

I think the topic (40hp engine) is of sufficient interest
internationally to justify some form of permanent address on the
internet. The problem is only going to become worse.

-R.S.Hoover

[Morgans[_2_]]

"Stealth Pilot" > wrote

> rotec is not in consideration. my target is a light 40 hp engine for
> single seat aircraft.

How about a Harley Davidson motorcycle engine? I see some guy has been
using one for airplane use.

It seems like it would have a lot of things going for it. Air and oil
cooled, power output shaft designed to drive a primary drive belt, just like
could be used to drive a prop. Light and should have plenty of power for
your use. Plenty engines available, different sizes, and good supplies of
aftermarket parts.

The only drawback is the uneven drive pulses, and only two cylinders-at
that. Still, it seems to work for at least one guy.

I saw a three cylinder Harley-like engine on a TV motorcycle show once. I
wonder how that would work.

And, it sounds cool for a bonus!
--
Jim in NC

[Anthony W]

Morgans wrote:
> How about a Harley Davidson motorcycle engine? I see some guy has been
> using one for airplane use.
>
> It seems like it would have a lot of things going for it. Air and oil
> cooled, power output shaft designed to drive a primary drive belt, just like
> could be used to drive a prop. Light and should have plenty of power for
> your use. Plenty engines available, different sizes, and good supplies of
> aftermarket parts.
>
> The only drawback is the uneven drive pulses, and only two cylinders-at
> that. Still, it seems to work for at least one guy.
>
> I saw a three cylinder Harley-like engine on a TV motorcycle show once. I
> wonder how that would work.
>
> And, it sounds cool for a bonus!

I don't think a HD engine has sufficient cooling fins on the cylinder
heads to run at a steady power output and not melt. It's the VW problem
all over again. And as has already be discussed, casting cylinder heads
is no easy job.

If someone were to custom build an engine, there are HD parts that would
make the project go a bit quicker. I once sketched up an opposed twin
using parts from the all aluminum head HD engine back in the mid 1980s.
It was a somewhat doable project but I wasn't thinking of it as an
aircraft power plant but rather an modernization of the very rare WWII
military Harley XA.

Tony

[Bob]

On May 16, 11:42*pm, Anthony W > wrote:
> *It's the VW problem
> all over again. *And as has already be discussed, casting cylinder heads
> is no easy job.
>----------------------------------------------------------------------------------------------------------

Ummm.... well, not necessarily. If we could come up with a
professional pattern for a Lost Foam Casting we can come up with a
single-piece, one-cylinder cylinder head having nearly TWICE the
cooling-fin are of the stock VW cylinder head.

No, not like the Scat head, but similar to it, with regards to one-
head-per-cylinder. What makes it different is that you need TWO
castings... because the Volkswagen's exhaust valves are on the
corners.

The main advantage here is the high precision you can get using Lost
Foam Casting. Plus, there's no need for any DRAFT in the pattern.
That means you can produce up to ten fins per inch (!) from a
casting. But you're looking at a minimum run of about 5000 units to
get the price down to where it's affordable.... and it STILL doesn't
address the main issue, which is the fact we are running out of VW
engines. But if we DID have such heads we could assemble a 140cid
engine capable of delivering an honest 65 hp.

-R.S.Hoover

[Anthony W]

Bob wrote:
> On May 16, 11:42 pm, Anthony W > wrote:
>> It's the VW problem
>> all over again. And as has already be discussed, casting cylinder heads
>> is no easy job.
>> ----------------------------------------------------------------------------------------------------------
>
> Ummm.... well, not necessarily. If we could come up with a
> professional pattern for a Lost Foam Casting we can come up with a
> single-piece, one-cylinder cylinder head having nearly TWICE the
> cooling-fin are of the stock VW cylinder head.
>
> No, not like the Scat head, but similar to it, with regards to one-
> head-per-cylinder. What makes it different is that you need TWO
> castings... because the Volkswagen's exhaust valves are on the
> corners.
>
> The main advantage here is the high precision you can get using Lost
> Foam Casting. Plus, there's no need for any DRAFT in the pattern.
> That means you can produce up to ten fins per inch (!) from a
> casting. But you're looking at a minimum run of about 5000 units to
> get the price down to where it's affordable.... and it STILL doesn't
> address the main issue, which is the fact we are running out of VW
> engines. But if we DID have such heads we could assemble a 140cid
> engine capable of delivering an honest 65 hp.
>
> -R.S.Hoover

I don't know what it cost this guy to have his engine parts cast but the
article is certainly enjoyable to read...
http://www.flashbackfab.com/pages/excel00.html

I wasn't thinking of continuing to use VW engines, I was talking about
making a boxer twin out of Harley-Davidson engine parts. The 80cid
engine of about 1984 on would be the one I was thinking about but the
newer 88cid engine would be worth looking at too.

when I was first thinking about this project I had the opportunity to
pick up a damaged BMW R90 engine and my crazy idea was to start with the
Beemer crank and built something custom from there. However that was
long ago and I don't have the resources now that I did back then...

Tony

[[email protected]]

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

[Peter Dohm]

"Morgans" > wrote in message
...
>
> "Stealth Pilot" > wrote
>
>> rotec is not in consideration. my target is a light 40 hp engine for
>> single seat aircraft.
>
> How about a Harley Davidson motorcycle engine? I see some guy has been
> using one for airplane use.
>
> It seems like it would have a lot of things going for it. Air and oil
> cooled, power output shaft designed to drive a primary drive belt, just
> like could be used to drive a prop. Light and should have plenty of power
> for your use. Plenty engines available, different sizes, and good
> supplies of aftermarket parts.
>
> The only drawback is the uneven drive pulses, and only two cylinders-at
> that. Still, it seems to work for at least one guy.
>
> I saw a three cylinder Harley-like engine on a TV motorcycle show once. I
> wonder how that would work.
>
> And, it sounds cool for a bonus!
> --
> Jim in NC
>
IIRC, the then current Harley was a recommended powerplant for some ot the
Mignet "Flying-Flea" aircraft of the period c1970.

Peter

[Charles Vincent]

Stealth Pilot wrote:

>
> hoover you are proof positive that old dogs can learn new tricks!
> I note the use of the word Holden :-) and punch that upturned thumb to
> the sky thinking yesss hoover you are a champion :-) :-)
>

Personally, I want to see a flying commie-knocker ;')

Charles

[routund]

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.

[bildan]

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.

[flybynightkarmarepair]

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

[Stuart Fields]

"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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[Tim[_8_]]

"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.

[bildan]

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.

[Dancing Fingers[_2_]]

Years ago there was an article in Kitplanes about someone trying to
use a Honda Goldwing engine. Did that ever come to fruition?

[bildan]

On May 20, 2:01*am, Dancing Fingers > wrote:
> Years ago there was an article in Kitplanes about someone trying to
> use a Honda Goldwing engine. *Did that ever come to fruition?

I've not heard of it.

Actually, the cylinders, pistons, rods and crank from the Honda 1800cc
Valkyrie flat-6 combined with a aircraft style case would hit the spot
for fans of smaller airplanes. However, it would still need a PSRU.

Nobody had mentioned the Rotec radials.
See: http://www.rotecradialengines.com/

[cavelamb[_2_]]

bildan wrote:
> On May 20, 2:01 am, Dancing Fingers > wrote:
>> Years ago there was an article in Kitplanes about someone trying to
>> use a Honda Goldwing engine. Did that ever come to fruition?
>
> I've not heard of it.
>
> Actually, the cylinders, pistons, rods and crank from the Honda 1800cc
> Valkyrie flat-6 combined with a aircraft style case would hit the spot
> for fans of smaller airplanes. However, it would still need a PSRU.
>

something like 260 pounds for 80 hp?

[bildan]

On May 20, 10:27*am, cavelamb > wrote:
> bildan wrote:
> > On May 20, 2:01 am, Dancing Fingers > wrote:
> >> Years ago there was an article in Kitplanes about someone trying to
> >> use a Honda Goldwing engine. *Did that ever come to fruition?
>
> > I've not heard of it.
>
> > Actually, the cylinders, pistons, rods and crank from the Honda 1800cc
> > Valkyrie flat-6 combined with a aircraft style case would hit the spot
> > for fans of smaller airplanes. *However, it would still need a PSRU.
>
> something like 260 pounds for 80 hp?

I wouldn't think so. The crank is light enough to use as a dumbbell
and that's heavier than the cylinder blocks. Just guessing of course,
but I'd say 180 lbs for 100HP which is better than an O-200.

[cavelamb[_2_]]

bildan wrote:
> On May 20, 10:27 am, cavelamb > wrote:
>> bildan wrote:
>>> On May 20, 2:01 am, Dancing Fingers > wrote:
>>>> Years ago there was an article in Kitplanes about someone trying to
>>>> use a Honda Goldwing engine. Did that ever come to fruition?
>>> I've not heard of it.
>>> Actually, the cylinders, pistons, rods and crank from the Honda 1800cc
>>> Valkyrie flat-6 combined with a aircraft style case would hit the spot
>>> for fans of smaller airplanes. However, it would still need a PSRU.
>> something like 260 pounds for 80 hp?
>
> I wouldn't think so. The crank is light enough to use as a dumbbell
> and that's heavier than the cylinder blocks. Just guessing of course,
> but I'd say 180 lbs for 100HP which is better than an O-200.

Better go check the Kitplanes article, because it was way heavy!

[[email protected]]

On May 20, 2:15 pm, bildan > wrote:
> I wouldn't think so. The crank is light enough to use as a dumbbell
> and that's heavier than the cylinder blocks. Just guessing of course,
> but I'd say 180 lbs for 100HP which is better than an O-200.

The TCDS says the O-200-A is 190 lb. My experience with the engine
makes me wonder about the 100-hp claim. The C-90 I flew had more pull.

Dan

[[email protected]]

On Wed, 20 May 2009 13:15:15 -0700 (PDT), bildan >
wrote:

>On May 20, 10:27Â*am, cavelamb > wrote:
>> bildan wrote:
>> > On May 20, 2:01 am, Dancing Fingers > wrote:
>> >> Years ago there was an article in Kitplanes about someone trying to
>> >> use a Honda Goldwing engine. Â*Did that ever come to fruition?
>>
>> > I've not heard of it.
>>
>> > Actually, the cylinders, pistons, rods and crank from the Honda 1800cc
>> > Valkyrie flat-6 combined with a aircraft style case would hit the spot
>> > for fans of smaller airplanes. Â*However, it would still need a PSRU.
>>
>> something like 260 pounds for 80 hp?
>
>I wouldn't think so. The crank is light enough to use as a dumbbell
>and that's heavier than the cylinder blocks. Just guessing of course,
>but I'd say 180 lbs for 100HP which is better than an O-200.


They ARE heavy because the trans is integral - and the trans does not
handle the prop as a PSRU. One I am aware of lost the gears in several
hours of flying.

[Stealth Pilot[_2_]]

On Wed, 20 May 2009 17:59:24 -0700 (PDT),
wrote:

>On May 20, 2:15 pm, bildan > wrote:
>> I wouldn't think so. The crank is light enough to use as a dumbbell
>> and that's heavier than the cylinder blocks. Just guessing of course,
>> but I'd say 180 lbs for 100HP which is better than an O-200.
>
>The TCDS says the O-200-A is 190 lb. My experience with the engine
>makes me wonder about the 100-hp claim. The C-90 I flew had more pull.
>
>Dan

my docs say "rated horsepower" which makes me think that there is a
calculation used to derive the figure not an actual 2750rpm
measurement. the 74hp at 2500 rpm seems to be measured.

[[email protected]]

On May 21, 5:21 am, Stealth Pilot >
wrote:

> my docs say "rated horsepower" which makes me think that there is a
> calculation used to derive the figure not an actual 2750rpm
> measurement. the 74hp at 2500 rpm seems to be measured.

They normally take a brake horsepower reading, with the engine at
redline RPM and full throttle. Torque times RPM times 6.28 divided by
33,000 gives HP.

BUT:
The O-200 makes its 100 hp at 2750. The C-90 its 90 hp at 2475.
Everyone knows that drag increases by the square of the increase in
speed, so the O-200's prop theoretically has 19% more drag than the
C-90's. The C-150's prop is narrower and I think a bit shorter than
the prop on the Aircoupe I flew with its C-90, so its drag might be a
bit less to start with, but overall the losses will still be higher at
2750.
So adding RPM to gain hp is a poor way to go. That's why PSRUs
are better than direct-driving a tiny prop at 4000 RPM. And it's also
why a 110-hp Corvair, if it's running at 3300 or some such RPM, isn't
going to outdo an O-200.

Dan

[Peter Dohm]

"Stealth Pilot" > wrote in message
...
> On Wed, 20 May 2009 17:59:24 -0700 (PDT),
> wrote:
>
>>On May 20, 2:15 pm, bildan > wrote:
>>> I wouldn't think so. The crank is light enough to use as a dumbbell
>>> and that's heavier than the cylinder blocks. Just guessing of course,
>>> but I'd say 180 lbs for 100HP which is better than an O-200.
>>
>>The TCDS says the O-200-A is 190 lb. My experience with the engine
>>makes me wonder about the 100-hp claim. The C-90 I flew had more pull.
>>
>>Dan
>
> my docs say "rated horsepower" which makes me think that there is a
> calculation used to derive the figure not an actual 2750rpm
> measurement. the 74hp at 2500 rpm seems to be measured.


The rated power is achieved at standard sea level temperature, pressure and
humidity; and is also a maximum permissible limit, even when the combination
of temperature, barometric pressure and humidity might enable the engine to
produce more power than the maximum for which it was certified.

[jan olieslagers[_2_]]

Bob schreef:
> I think the topic (40hp engine) is of sufficient interest
> internationally to justify some form of permanent address on the
> internet. The problem is only going to become worse.

Well here goes for what it's worth: a certain Mr. Doutard from France
fitted a reduction to the 2-cylinder Citroen Visa car engine.
Unfortunately he passed away some 6 year ago and I could no trace of a
follow-up. The idea seems excellent though. Actually there is one such
engine in my car right now but of course it is not on offer.

The guy in France from whom I got it had heard rumours of some Italian
doing much the same thing, with the extra addition of a turbo-charger.
That seems a bit weird on a 2-cylinder boxer... Who knows more?