DIY Two-Stroke Engine

Jim Wilkins schreef:
On Mar 6, 8:45 pm, wrote:
...What's UL use?
I think UL here means UltraLight, a minimally regulated, tiny but
MANNED aircraft.
http://www.eaa.org/Ultralights/

I thought the same, but should like to add that in several countries the
"ultralight" definition allows bigger planes, closer to the newer US
light sport aircraft definition.

jan olieslagers schreef:
Jim Wilkins schreef:
On Mar 6, 8:45 pm, wrote:
...What's UL use?
I think UL here means UltraLight, a minimally regulated, tiny but
MANNED aircraft.
http://www.eaa.org/Ultralights/

I thought the same, but should like to add that in several countries the
"ultralight" definition allows bigger planes, closer to the newer US
light sport aircraft definition.

Come to think of it, several countries even allow them to FEMALES !

In article
,
bizguy writes
You could look at outboard motors as a starting point. In the past I
read of someone using a Mercury to get 100 hp in an aircraft.

That seems unlikely, to be honest. I've never met an outboard that
wasn't cooled by pumped water.

--
Nigel

When the only tools you have are an X3 mill, a
Colchester and assorted other stuff, every problem looks like a steam engine.

"Nigel Eaton" wrote in message
...
In article
, bizguy
writes
You could look at outboard motors as a starting point. In the past I
read of someone using a Mercury to get 100 hp in an aircraft.

That seems unlikely, to be honest. I've never met an outboard that wasn't
cooled by pumped water.

--
Nigel

There have been other uses of outboards that involved using a car-type
cooling system, with a radiator. A Bobsy SR2 sports-racing car of the 1960s
was very successful in the H-modified class using a Mercury outboard. I
think that was a 750 cc class.

--
Ed Huntress

On Sat, 6 Mar 2010 17:45:22 -0800 (PST), wrote:

On Mar 5, 6:56Â*pm, durabol wrote:
For the last few years I have toyed with the idea of building a
homemade two-stroke engine for UL use. What keyed my interest was
reading about homemade model aircraft engines and reading and watching
a re-enactment of the Wright brother's first flight with a replica
engine (not a two-stroke engine).

Has anyone made a 2-stroke engine from scratch? One may need to cast
aluminium, may need a lathe and milling machine with boring head and
hone or perhaps the boring and honing of the cylinder and bearing
journals could be farmed out. A commercial carburetor and piston could
be used. Two-stroke engines seem simple enough that home construction
may be possible, if not practical.

A direct drive engine will be that much heavier when you take into
account the weight of the drive reduction system. I have calculated
the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
cylinder and crankcase wall thickness and a 1.25" dia crank.

I have got some idea of port-time-area from the freeware computer
program called "BiMotion". I'm not sure how good the data is for
lowish speed engines but I guess it is a start. I have also worked up
a spreadsheet for similar information.

I don't think a reed valve system is needed for this engine since it
is only going to operate at a fairly narrow rpm range and the port
timing isn't critical. Piston ported valves offer similar performance
to other induction types but only over a narrow rpm range which is
what I have planned for the engine. I plan to build an engine with a
restrictive exhaust to ensure no fuel escapes. I have heard that
piston ported engines can spit some fuel out of the carb at idle but
this doesn't seem like a major problem. Rotary valves via crank shaft
induction (disk or drum valves as well) is an interesting idea but I
don't think I need the critical timing they provide.

I was planning on using the largest two-stroke piston (not a diesel
piston) I could find and using the largest stoke that was reasonable,
something like 90x105mm

Brock

There's any amount of engineering info out there on two-strokes,
books have been written. They were a staple project in The Model
Engineer magazine for years, should you want to look that up. What's
UL use?


I believe he's talking UltraLight Aircraft.

Why a two stroke? The commercially available ones are bad enough. I
hate even taking my chainsaw up a ladder - why would I want to fly
behind one???
A good, small, light supercharged 4 stroke or diesel??? Now that's
something completely different!!!


You'd be basically recreating a commodity item. Resurrect one from a
defunct snowblower, weed-whacker or Lawnboy and spend more time on
figuring out the project you want to drive. The engineering's done,
you aren't likely to improve on what's already been built. Want
overhead valves? Been done. Rotary valves, ditto. Fuel injection,
same. Separate lube system, been done. Opposed twins, flat fours,
square fours, Vs, Xs, Ws, all been done. Separate forced air pumping,
too. They basically suck thermodynamically except the one feature
they've got going is power-to-weight ratio, the small ones pump out a
lot of horsepower, usually at high RPM, for their size. For that you
can go with an existing engine and spend more time on the rest of the
project.

Stan

On Sun, 07 Mar 2010 13:51:46 +0000, jan olieslagers
wrote:

Jim Wilkins schreef:
On Mar 6, 8:45 pm, wrote:
...What's UL use?
I think UL here means UltraLight, a minimally regulated, tiny but
MANNED aircraft.
http://www.eaa.org/Ultralights/

I thought the same, but should like to add that in several countries the
"ultralight" definition allows bigger planes, closer to the newer US
light sport aircraft definition.
Like up here in Canada - 1238 lbs? as long as it stalls under 45 MPH.
It can have a Lycoming IO-235 in it if you want.

On Sat, 6 Mar 2010 21:36:28 -0800 (PST), bizguy
wrote:

You could look at outboard motors as a starting point. In the past I
read of someone using a Mercury to get 100 hp in an aircraft.
Harold
Had a 100HP Evinrude V4 I was thinking of putting in a plane - untill
I remembered all the problems I'd had with 2 strokes in boats, lawn
mowers, mototcycles, weed-eaters, and chain saws over the years.

"jan olieslagers" wrote in message
...
Morgans schreef:

You might do well to consider a 2 stroke supercharged diesel engine. You
make one of those, and make it scaleable by adding more banks of
cylinders,
and the flying world will beat a path to your doorstep.

Hm. The flying world did not exactly beat any kind of path to the doorstep
of www.dair.co.uk, though they did exactly that. Wilksh company wasn't far
off, either, with equal lack of big success.

I suspect the two cylinders with 4 pistons is a bit unconventional, and will
have to work all the harder to prove itself.

I think the web page is about 10 years old, since much activity has taken
place. It looks like it is a bit heavy when you add all it needs to run in
an airplane, too. How about price? No mention of that, on the current
pages.
--
Jim in NC

"Morgans" wrote in message
...

I suspect the two cylinders with 4 pistons is a bit unconventional, and will
have to work all the harder to prove itself.

2 pistons per cylinder is not unconventional in the stationary diesel world.

Vaughn

On Mar 6, 2:44 pm, "Morgans" wrote:

If so, when is the last time you saw a direct drive 2 stroke aircraft
engine? Not me.

McCullough made two-stroke opposed four-bangers for miltary target
drones in several different sizes. Many of those were sold surplus and
found their way into several homebuilts and a lot of Bensen
Gyrocopters. I once owned one; the vibration was awesome, as was the
fuel consumption.

http://www.combatairmuseum.org/engin...ch0-100-1.html
http://media.photobucket.com/image/M...ctoshow026.jpg

And here's a video of one powering a Hummel Bird:

http://www.youtube.com/watch?v=ITB_dxbCTUk

Dan