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
Underwriter's Laboratories?
> 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.
Certainly not practical in the "it saves you money" sense, but who cares?
> 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.
Piston porting isn't optimum at any speed -- crank-timed or reed valve
induction is much better.
But piston porting is certainly easier.
> 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
I'm still a home-built engine wannabe, but I'm working on it. Here are
some resources:
http://www.lindsaybks.com/prod/sub/engines.html
http://www.modelenginenews.org/
--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
Brock, you do have some ambition with a project like that. Sounds like
your basically re-inventing the wheel. Just my opinion, wouldn't it be
more cost effective & easier in the long run finding an antique wing
dinger & rebuild that? I've seen some pretty cool 2strokes over the
years. You've eliminated all those engineering variables that your
scratching your head about. When done, you have restored piece of
history, & may be $worth$ more that what you have into it? Again thats
just me, I dont like re-inventing the wheel. Some very smart guys
already did that. I like improving that wheel & making it spin faster.
The rotary wrankel engines have always intrigued me. Very simple,
compact, comparable with 2 stroke & can be made w/o a lot of
castings.
Good luck!
--
\|||/
(o o)
______.oOO-(_)-OOo.____________________
~ Gil ~
the HOLDZEM©® king
Member of
==American Toolmakers==
using the "old world" ways
with yesterdays technology
building
Tomorrows Dreams
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280451279735
There are several organizations for hobbyists building smaller (model
sized) IC engines. Check out Model Engine Builder magazine (they have a
web site.
I suggest you build a model engine first. That would help answer the
question of whether it is practical for you. Sounds like you may not be
a skilled machinist yet, and I would become a master machinist before I
bet my life on a homemade engine.
I met a guy in Edmonton (St. Albert ) who made working models of
historical engines such as the Liberty engine. Really beautiful piece
of modeling and was featured in a modeling magazine. Its power/weight
output was not enough to power a model plane.
If your intention is to power a model plane you are much better off
buying a model engine and tinker with that to boost its performance.
Not much reward in building a two stroke engine from scratch. For a
large two stoke you can modify a weedwacker engine (25 cc) A
snowmobile engine powers those military drones.
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?
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
> > For the last few years I have toyed with the idea of building a
> > homemade two-stroke engine for UL use.
> > Brock
>
> ...What's UL use?
> Stan
I think UL here means UltraLight, a minimally regulated, tiny but
MANNED aircraft.
http://www.eaa.org/Ultralights/
I looked into it, flew a hang glider a few times, then gave it up for
the safer hobby of racing dirt bikes.
jsw
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 !
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.
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
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!!!
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.
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.
>In article
><9446d3d2-3e78-45fc...@19g2000yqu.googlegroups.com>,
>bizguy <bizol...@clear.lakes.com> 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.
Can be cooled very well with a radiator - the interface to connect a
rad instead of the raw water cooling was possible, but not simple.
There were "saltie" conversions that used a sealed cooling system and
a heat exhanger availble for some of the outboards of the period, but
they were not common. Very common with stern-drives (4 stroke)
Actually, there WAS a commercially available helicopter kit that DID
use the V4 Evinrude power head - and I believe I've seen refference to
the 6 cyl Merc "black max" in experimental aircraft use too.
I had a really nice 5 HP Briggs and Stratton outboard on my previous
sailboat. It was air cooled. But it was the exception that proved
the rule...
http://www.duckworksmagazine.com/03/r/columns/cupp/06/index.htm
--
Richard Lamb
http://www.home.earthlink.net/~cavelamb/
Without knowing anything much about ultralights (beyond they look fun
but dangerous) wouldn't the obvious source of lightweight engines in
that power range be motorcycle engines?
-- Peter Fairbrother
How about a 2 stroke radial developed by Pontiac for their X-4 1,500lb
car in 1969.
http://www.popsci.com/archive-viewer?id=EyoDAAAAMBAJ&pg=43&query=homebuilt+airplanes
Popular Science has just released ALL of their archives for free
http://www.popsci.com/archives and found it while searching for
homebuilt airplanes.
--
A man is known by the company he keeps- Unknown
Anyolmouse
Too big for ultralight I would guess but seems like
a very fine plan for a light aircraft engine.
160 hp and upwards
V4 two stroke diesel.
Has crank driven air pump + turbo.
No electrics *at_all* for engine operation.
Will continue running if air pump OR turbo fails.
Will run at about 50% power (check web site for details)
if all water is lost.
Seems a *very* fine thing to me.
Expected to be accepted as a FAA certified
aero engine this year.
200hp planned.
V8 in the future.
Oh yes - direct drive. No gears needed.
> That link redirects to a poster site.
> Tim Wescott
http://www.deltahawkengines.com/
Any day now.....
jsw
saw the price? 71 Thou $$$$$$
sorry, 'only' 62.500$ for Deltahawk
Yes yes, nice stuff though expensive. But the original question was
about building one's engine from scratch.
After spray cans you want yet another safety rant?
jsw
Not out of line for an engine that's capable of being certified but
hasn't been yet.
Aero engines are expensive. That's why folks go to great lengths to
modify car engines to fly airplanes. When they're done, the engines are
-- expensive.
THAT, more than likely, just won't happen.
Fred Blanton did it.
But it took his entire adult life time.
So this thread is about TALKING about building
and engine from scratch.
Not actually building one...
But the performance wasn't high.
The Wright Brothers did it, over the space of a year or two, and even
though the performance wasn't high it was still good enough!
Talking about building stuff can get you a lot more bang for the buck
than actually doing it. Witness me, with several engine parts sitting
next to a lathe that's been idle for days, and last had an accessory for
a completely different engine built on it, not a part for the engine
that's half-done and sitting next to it.
Yep!
Tha's how it happens...
:)
Tony
For the last 10 years.
> www.deltahawk.com
>
> Too big for ultralight I would guess but seems like
> a very fine plan for a light aircraft engine.
> Expected to be accepted as a FAA certified
> aero engine this year.
I'll believe it when I see that the first 25 are sold and flying. It has
been ready for production for the past 10 or more years, yet, it always a
year away from being released for production.
Hint: I'll win this bet.
--
Jim in NC
Surprise, Surprise. There is a two seat experimental Helicopter in
Australia that is undergoing flight tests as I write this. It is using the
Deltahawk two stroke diesel engine. see www.deltahelicopters.com.au
Unfortunately the Deltahawk engines are priced right up there with the long
time proven Lycomings. It will take some time to really see if this engine
will demonstrate all the potential advantages inherent in the diesel
concept.
WHAT? Why, you could buy a life-size pine needle bear for less than
that. (someone posted this on the Wreck last week, and we all had
something to say about the website's, um, unique flair.)
http://www.whereartmeetstheheart.com/rcfaq.shtml scroll down
--
Stay centered by accepting whatever you are doing. This is the ultimate.
-- Chuang-tzu
Brock
That RPM isn't going to give you much prop efficiency.
A more spindly engine with higher displacement may be lighter overall --
and certainly mechanically simpler -- than a little fast engine and a
speed reducer.
'Restrictive' exhaust isn't a good way to avoid venting unburnt fuel,
and it will really clobber performance. If you're really trying to
get good performance, especially over a narrow band, then you really
need to consider using tuned pipes (AKA "Expansion Chambers"). Gordon
Jennings "Two Stroke Tuners Handbook" covers most everything you need
to design a two-stroke.
4000 RPM is pretty low for a two-stroke. The tuned length for the
pipe(s) would be around 6 FEET.
Ship's two-stroke diesel engines top out at less than 200RPM.
I don't think they use tuned pipes, but if they did I suppose they'd
have room.
Don't need them. They all have massive
blowers for scavenging.
I believe EMD built locomotive 2-strokes that
had a set of exhaust valves in the head and
a blower port that was opened at the bottom of
the stroke. No tuning, the blower was plenty
to force out the exhaust and fill the cylinder
with fresh air.
They are also supercharged. (forced induction)
And at 200 RPM there is LOTS of time to purge and fill. Volumetric
efficiencies are pretty good.
Consider building a Kemp G2 replica. If you can do that there might
even be others that would want to buy them.
2 cyl - 4 cycle low end HP.
http://bourkeengine.net/home.htm
http://www.rogerrichard.com/14507.html
Another very interesting project worthy of following.
I was surprised - to see that the site hasn't been updated since 2005...
I didn't see anything about an engine for under $100 either.
I would indeed be very much surprised to find such an engine
available
for that price, unless it is a very simple model engine, as opposed to
one that might be used on a weedhopper.
>
> I was surprised - to see that the site hasn't been updated since 2005...
>
> I didn't see anything about an engine for under $100 either.
There are least three (3) weedhopper Yahoo groups:
http://groups.yahoo.com/group/weedhopper/
http://groups.yahoo.com/group/WUPA/
http://groups.yahoo.com/group/Weedhopper-Ultralights/
The third appears to have fallen victim to spam, but there
may be something of interest in the earliest postings.
--
FF
Perhaps he was looking at a weedwhacker website...
--
Ff