Recently I spoke to the Engineering Manager of a company which
manufactures rotary engines for aircraft. I mentioned to him that I
read about a "rotary" engine which is a kind of Wankel engine, but has
two paddles in the shape "X". He told me that the name of such a type
of engine is "nu-teddy" because of the crossed paddles. I did a search
on the Internet, but could not find any mentioning of "nu-teddy".
Obviously, I wrongly spelled it. Maybe someone can tell me what was
the term ? Thanks.
I read about a rotary engine called something like "nu-teddy".
But I can't find any mention of "nu-teddy" on the Internet.
If I misspelled it, can someone can tell me the correct term?
"Nutating" (oscillating), I think. If it's the one I'm thinking of,
its the McMaster Motor. There is only one "paddle". The brother of
a guy I worked with at 3M invented it and he used to show us its
progress at our monthly retirement breakfast meetings. the brother is
now gone, but the commercialization continues. Last I heard, they had
a large order from a cab company in England.
You can see it at >
Beladi Nasralla wrote:
BTW in relation to aircraft, "rotary" also means a radial in which the
crankcase rotates, & the crankshaft is stationary. See Gnome Monosoupape
(ie 1-valve), and similar designs. Popular in WW1, but long gone now.
The McMaster (wobble) motor website causes me to pause when I read
hyperbole like this: "Each power stroke results in very smooth, high
torque, equivalent to an eight-cylinder engine." The Technical
Information portion of the website consists of 3 paragraphs and the
website looks like it was last updated in 2000. I suspect that one of
of many significant technical issues to be solved will be designing
seals for the wobbling rotor.
The idea has been around for quite a while and the latest spin is to
make it run on hydrogen. Count this as yet another automotive version
When I saw the comment about hydrogen I guessed that the engine is such a
stinking polluter that hydrogen is the only thing that could get it passed
It sure is interesting though. If somebody could just come up with clever
geometry like that without having reciprocating, sliding seals. This isn't
the first engine with that problem. It was solved pretty well in the Wankel
but Renault's wobbly engine never did get it solved.
According to the website the motor is the centerpiece of a project
involving "A new engine; A new fuel source; A new source of power to
assist in the production of the fuel". The company address is at a
University and they were apparently looking for funding from a variety
of sources including a DOE grant. Ultimately their goal appears to be
money from licensing production: "It is anticipated the McMaster
Motor's technology will be licensed to multiple industry sources for
I don't know if this is going beyond the dream stage.
Rotary engines were used in aircraft long ago. While they were
powerful little motors they had several problems which limited their
Just to confuse things modern-day Rotary engines of Wankel design have
been used in aircraft although not widely.
Well, yes, but websites that trumpet the 10 most important benefits of
a given product but say nothing on the downside do not strike me as
unbiased. Indeed I start thinking about sales hype.
There have been several promising engine designs over the years that
have come forth only to die a slow death. One I remember was a
resurrection of the old Sterling Motor to run a generator/battery
driven electric car. Seals were the biggest problem. The motor would
run fine until the loud pop told of a broken seal, exploded hydrogen
and rapidly declining mph.
I'm sure the problems of that design could have been fixed but the
costs of doing so would have been considerable. The result mwas
likely not a marketable product because of the development cost.
Among real companies are:
Possibly Wankel AG (not sure of their current status--Wankel Gmbh went
under and Wankel AG is the remains under new management)
Moeller Skycar has an engine manufacturing subsidiary, but like all
things Moeller, one should believe it when they deliver a product to
If you look at it the right way, any turbojet/turbofan/turboprop is a
rotary engine. Probably more efficient than anything using a non-
continuous combustion cycle. Don't know of any other type approved
for aircraft use. I think it was the BD-5 that was designed to use a
Wankel snowmobile engine and there were some small model-sized Wankel
glow-plug engines, don't know of anything else recently that's
actually flown and isn't a magnet for venture capital and/or
government research contracts, e.g. vaporware.
Actually Teledyne Continental has licenced the Norton Rotary engine,
and Avco Lycoming, in concert with Deere and Co are also working on a
rotary engine concept. (or have been in the last 15 years - no idea at
what stage they are today)
Turbojet/turbofan/turboprops also unless you luck into military
surplus cost a mint.
There are numerous homebuilt aircraft flying with rotary engines.
Here's a list of some that are flying or near completion
Most are based
on the Mazda 13-B. The things seem to be robust the same way that
WWII radials were robust.
You are correct. There are still rotary engined aircraft flying
today, but few and far between, and none are new. I also do not
believe that there are any new rotary engines produced, but there are
still many new and varied radial engines in full production today.
With the exception of "model engines" of course. The model
engineering engines come in two basic flavours...scaled sizes of
prototypes, and a large variety of custom designed. There are always
a couple of each at NAMES, some even run in the demo area.
The "rotary" engine referred to in other posts are Wankels (mostly
RX-7, 13-B's), and to me these are rotory rather rotary.
Rotary engines rotate the cylinders and hold firm the crank, so the
Rotory engines are those as in Wankel products, where they use a rotor
with a shaft for output, rather than conventional pistons and crank.
And then there is the Rotax line of engines, which are much used in
Ultra-light aircraft, but are neither rotary or rotory nor radial.
Just conventional air cooled recips.