what engines are making successful aero engine conversions?

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

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

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

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

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

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/gener...391-1-1-2.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/technol...Industrial.pdf
http://www.fordpowerproducts.com/For...f/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/

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.

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

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.)

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.