John, the Paul Lipps article is really interesting and I am certainly considering one as my Q is rev limited in cruise even with its 60x70 prop. As the engine is a C-90 (but with O-200 innards) I don’t think I need a coarser pitch prop, so it could be its efficiency. It doesn’t have a particularly good finish (which I hope to fix soon), but the ELIPPSE looks a good idea. I am really surprised at how yours looks though, very different from the 3 blade versions in the Paul Lipps article in the Experimenter magazine. Wider looking and without the long, thin outer parts. Do you know why this would be? Maybe it’s because it’s a 2 blader, or the diameter compared with max aircraft speed?

Cheers

Chris



From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of Jon Finley
Sent: 13 April 2010 04:20
To: Q-LIST@...
Subject: RE: [Q-LIST] Diesel Q1, update, and propeller question.





Roger,

His name is Paul Lipps. Company name is Ellipse. Paul is a genius. Refer to his Contact! Magazine articles for details (www.ContactMagazine.com)

Paul designed a prop for me and I built it. I've flown it a couple of times but my engine is producing a little less power than Paul believes it should so we are working on that (cannot get the desired RPM with the prop). This prop is roughly 10 mph faster at 800 less RPM (31% more efficient than my Warp Drive). Photos at:
http://www.finleyweb.net/JonsStuff/Q2AircraftInfo/Propellor.aspx

A ground adjustable Warp or Ivo prop are great for initial testing. They are not usually the best for optimal performance but certainly help get you in the ballpark when you have no known values. I suspect either prop with in flight adjustability would be really nice but I have no experience there. In neither case is the airfoil well optimized so neither will provide optimal performance.

Jon Finley
N314JF - Q2 - Subaru EJ-22
http://www.finleyweb.net/Q2Subaru.aspx

-----Original Message-----
From: Q-LIST@... <mailto:Q-LIST%40yahoogroups.com> [mailto:Q-LIST@... <mailto:Q-LIST%40yahoogroups.com> ] On Behalf
Of Isaksson Roger
Sent: Monday, April 12, 2010 5:50 AM
To: Q-LIST@... <mailto:Q-LIST%40yahoogroups.com>
Subject: Re: [Q-LIST] Diesel Q1, update, and propeller question.

Thanks Mike,

It is not an electronic pump, it's a simpler mechanical diesel pump,
as such the pump will provide suction up to the pump, but I will of
course have to try it out, I have two Diesel vehicles, an old Merc and
a VW Rabbit, both mechanical fuel pumps, none have an electrical feeder
pump.

The high pressure side in a Diesel mechanical pump system is from the
pump, and then individual plumbing to the injectors. I'm sure youv'e
seen underneath the hood of an old mechanical Diesel engine, and seen
the spiderweb of plumbing. Electronic injection have, as you say, one
high pressure pump, that feed all the injectors via a common rail. All
the injectors are opened with a built in solenoid in the injector, and
a computer is controlling it.

I don't want to experiment with, and rely on a computer to have the
engine running if I am flying, so there is a special purpose with using
a mechanical system. As long as the engine turns, everything
works....including it is sucking up fuel.

Yes you are right, there will be another set of numbers on the prop,
while cruising, and that was the heart of the matter, my question.

It is an electrical adjustable, so the pitch will vary.

If it is an overall suitable prop, in the first place, well I will of
course set it up on a bench, and work out all the bugs in it. Yes I am
aware that the power pulses in a Diesel is bigger, an I will have to
run it at least a couple of hours, on different settings and examine
every screw nut and bolt as I go.

However, I am far from that point, the engine is still on order, and it
will take some time to take it apart, and go over it with a fine comb,
strip it, and so on.

No the whole idea with my question is if I added another blade, same
diameter, what would happen, I don't want to drop down in diameter.

An earlier poster showed a really good article from this guy that had
built his own props, that looks like nothing else.

Think the guys name was Lippie, and he calls his props Ellipsie or
something like that.

He seems to have strong arguments in his case, evidently his props are
doing a darn good number, so he's definitely onto something.

He claims that a lot of data that is floating around in the aircraft
community is false or wrong, or based on non applicable
applications (data stemming from a time when everybody and his brother
had a radial engine) , especially then in issues like, number of
blades, and cowling resistance.

Roger

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