Nitrous Oxide for towing safety?

[Jason Payne]

Just a thought. Wanted to see what you guys thought. I know that FAA
aproval would never happen, but seems like a good idea to me.

You could easily and safely run a 100hp shot of NO2 for the first 10-15
seconds of a takeoff roll in an 0-470 or similar motor, and get to 100 feet
and 65 knots a lot quicker than without, increasing safety margins.

NO2 is especially nice in a heat soaked motor because the shot cools the
intake air a good 30-50 degrees...

From being in a ASH-25 at a full 750 kilos on a hot Uvalde day that another
100 hp would really help getting off the ground if you are not behind a big
motor like Scratch.

[Jim Phoenix]

Back in the old days water-meth worked pretty well, same basic effect. I
think Metros still use it, at least they did 10 years ago. Handy in the
Convair 580's as well - like, they needed more horsepower?

You just needed to be careful not to run out of water-meth at the wrong
time.

Jim

"Jason Payne" <pay...@stanford.edu> wrote in message
news:c25ru6$54h$1...@news.Stanford.EDU...

[Dave Nadler YO]

Did you mean nitrous for the tow-pilot ?
Easier installation and a more pleasurable view of the trees
at the end of the runway ?
See ya, Dave

"Jason Payne" <pay...@stanford.edu> wrote in message news:<c25ru6$54h$1...@news.Stanford.EDU>...

[Joseph L. Hyde]

"BACK IN THE OLD DAYS" Hey I've flown planes recently using water
meth.....rolls dart and garretts.....oh wait that has been over 20 years
ago....never mind.....

"Jim Phoenix" <jphoe...@comcast.net> wrote in message
news:xaOdnQZM-f-...@comcast.com...

[Jim Phoenix]

Back in the REAL old days, we had alcohol tanks in the DC-4's, but not for
water meth, for the props. Lessee - those REAL old days were back in 1985 -
the last millennium.

But back to the subject at hand - shooting nitrous into a Lycoming presents
its engineering challenges, I suppose there are other methods of increasing
acceleration at takeoff. At Sugarbush they do a modified angle takeoff roll,
the geometry of that seemes to increase the initial tow speed, very
slightly. (The towplane is on the main runway - the glider in the grass to
the right , aft of the towplane. The glider is angled towards the runway anf
rolls up onto the runway during the takeoff roll.

Jim

"Joseph L. Hyde" <av8...@bellsouth.net> wrote in message
news:UU02c.52552$Tn.4...@bignews5.bellsouth.net...

[Bill Daniels]

OK, I guess this is a top post thread.

It ain't horsepower, it's the PROP. To improve the 0 - 20 acceleration,
improve the propeller. Have you ever tried to figure out how much power
actually gets to the tow hook on the glider from a 260 HP Pawnee? Maybe 20
HP?

At low speeds, as at the beginning of the TO roll, the tug's prop is mostly
stalled and converting little of the engines HP to thrust. As it
accelerates, more of the prop disc becomes unstalled and the prop picks up
efficiency and therefore more acceleration. A headwind helps a lot here.

So, what to do?

1. A constant speed prop reduces the blade AOA and lets the engine rev to
its redline RPM. (Noisy)
2. Big, slow turning props make much more thrust at low speeds than small,
high RPM props. (Quieter but require PRSU gearbox)
3. Ducted fans work really well at low speeds but lose out to a standard
prop at 100 MPH +. (A LOT quieter)

The ducted fan looks very good in that it can turn at crankshaft RPM while
producing several times the thrust of an unshrouded prop at zero airspeed.

So, why don't you folks living in a country blessed with friendly regulators
design and build a certified ducted fan tug using the minimum engine
necessary - say a 140 HP LOM M132CE. (Less fuel, less noise).
See: http://www.moraviation.com/

I imagine an airframe that looks somewhat like an Ogar. A cute trick would
be to make the fan and duct as one rotating unit constructed of carbon
fiber - this eliminates the problem of fan tip-duct clearance.

Bill Daniels

"Jim Phoenix" <jphoe...@comcast.net> wrote in message

news:WY2dnS41-tX...@comcast.com...

[Mike Lindsay]

In article <8uednXAeE6X...@comcast.com>, Bill Daniels
<bil...@comcast.net> writes

Something like that was developed here in the UK a few years ago.
It was a place STOL with a ducted fan and it could fly very slowly.
It was called the Optima and it was designed by a Mr Edgerly, who also
designed a sailplane, using unconventional materials.

Several examples were completed, more were under construction, but were
destroyed in a fire.

And isn't nitrous oxide N2O, not NO2 which is nitrogen dioxide?
>> >
>> >
>> >
--
Mike Lindsay

[Mark James Boyd]

Bill Daniels <bil...@comcast.net> wrote:
>OK, I guess this is a top post thread.
>
>It ain't horsepower, it's the PROP. To improve the 0 - 20 acceleration,
>improve the propeller. Have you ever tried to figure out how much power
>actually gets to the tow hook on the glider from a 260 HP Pawnee? Maybe 20
>HP?
>
>At low speeds, as at the beginning of the TO roll, the tug's prop is mostly
>stalled and converting little of the engines HP to thrust. As it
>accelerates, more of the prop disc becomes unstalled and the prop picks up
>efficiency and therefore more acceleration. A headwind helps a lot here.
>
>So, what to do?
>
>1. A constant speed prop reduces the blade AOA and lets the engine rev to
>its redline RPM. (Noisy)
>2. Big, slow turning props make much more thrust at low speeds than small,
>high RPM props. (Quieter but require PRSU gearbox)
>3. Ducted fans work really well at low speeds but lose out to a standard
>prop at 100 MPH +. (A LOT quieter)
>
>The ducted fan looks very good in that it can turn at crankshaft RPM while
>producing several times the thrust of an unshrouded prop at zero airspeed.

Great stuff, Bill. I hadn't thought before how a headwind
helps a fixed pitch prop on the ground. Interesting...

I'm still excited about turbines on self-launch gliders
(and small planes). I was disappointed to learn that
Avemco puts turbines, no matter how small, in
a different insurance category than regular ol' planes.
It turns out my insurance only covers borrowed aircraft
with one or less engines, six or less seats, and
non-turbine without floats.

So much for the twin turbine Sparrowhawk ;(
--

------------+
Mark Boyd
Avenal, California, USA

[Robert Ehrlich]

Bill Daniels wrote:
> ...

> 1. A constant speed prop reduces the blade AOA and lets the engine rev to
> its redline RPM. (Noisy)
> 2. Big, slow turning props make much more thrust at low speeds than small,
> high RPM props. (Quieter but require PRSU gearbox)

Both constant speed and low RPM through an appropriate gearbox are
provided in the Super Dimona we use as tow plane. The noise is noticeably
lower than with a conventional prop, although the prop is of slightly
lower diameter than most of them. The noise reduction was sufficiently
significative that we got some help from the general fundings for
noise reduction. If we didn't had a lot of problems with the engine,
this would seem a very good solution.