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gcrowder2
Joined: 09 Jan 2006
Posts: 136
Location: Golden, Colorado USA
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 Posted: Wed May 30, 2007 10:14 am Post subject: Lipps prop for Europa |
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| Quote: | .ExternalClass .EC_EmailQuote {margin-left:1pt;padding-left:4pt;border-left:#800000 2px solid;} On Monday, May 28, 2007, at 06:56 AM, Mike Gregory wrote:
Has anyone tried an Elippse propeller on a Europa? See article
www.batterson.net/EAA499/Issue77_8-13.pdf which makes some interesting
points about propeller design.
The referenced article is worth a read if you're interested in this topic. Pictures of an Ellipse prop on a Lancair are astonishing...at least they were to me. Intrigued, I emailed Paul Lipps, excerpt as follows:
To: elippse(at)sbcglobal.net
Subject: a prop for the Europa
Hi Paul,
I'm in the midst of building a Europa XS and your article (www.batterson.net/EAA499/Issue77_8-13.pdf) was brought to my attention in an online Europa discussion on optimizing propellers. Thanks for making the esoterica (somewhat) comprehensible to a non-techie like myself. Your thinking and design work is awesome!..w/ awesome results in efficiency.
I noted your ref. to Craig Catto...(Craig has made one Europa flyer quite happy (Glenn Crowder) and I've had some email exchanges w/ him on this topic; I think he is also is doing some fine work...I recall Craig as an audacious 15 yr. old carving his own props when the Easy Riser biplane hang glider was first being powered to start the ultralight movement...I was an ER dealer at the time, but that's another story.
Many Europas are flying w/ Warp Drive blades (62" dia.) in an Airmaster electric hub and there's general acknowledgment of some shortcomings of this arrangement; many are also using FP props. Though the conventional wisdom is that a variable pitch prop is essential to optimize performance in the Europa, Craig's prop for Glenn Crowder challenges that assumption. Most Europas are powered w/ the Rotax 912S or 914; a few have Subarus and Jabaru 3300s; there's one flying w/ a CAM 125 (Honda derivative) which I hope to use in my bird...engine comes w/ an SAE 1 mounting plate.
So my question to you is...would you be at all interested in looking into an optimum prop for the Europa? Are you set up for this, and how would you go about it? Does Craig do all your fabrication work? In your article you say,
I would like to design propellers for various and sundry
aircraft, but in order for me to design a prop for a plane, I
have to be able to form a drag model of the plane for my
equations. The best way to do this is to have one of my
props installed on a plane and then measure the planeÕs
performance with it. So far I only have the two props, and
the 2-blade is on loan for a race plane for Reno. I can
form a less-accurate model by measuring the chord and
angle of someoneÕs prop every inch from the spinner to
the tip and using that data, along with the full-throttle performance
of the plane with that prop to obtain the drag
model. This requires the use of a very accurate electronic
tach, and flying the plane around a wide circle
while measuring GPS-derived ground speed and holding
a constant altitude to minimize speed variations. ItÕs also
helpful to have a fuel-flow meter in order to determine
the actual installed engine horsepower, not the exaggerations
of some of the engine-makers!
I would be happy to attempt to generate the info and data which you would need.
Fred
Paul Lipps replied:
| Quote: | > Hi, Fred!
| Quote: | I have a 62" Great American prop which I have tested on my
Lancair and possibly I could loan that out for testing since I know
its characteristics. A '98 book I have lists the Europa as having a
wing area of 95 sq. ft. Since drag is pretty much proportional to wing
area on clean designs such as the Europa and Lancair. I have 125 HP, a
wing area of 77 sq. ft., and cruise at 201 mph TAS at 10,000' dalt.
With equal engine power and a retract gear, I would expect your TAS to
be 201*(77/95)^1/3 or about 187 mph/163 kt. with a high efficiency
prop, somewhat less with fixed gear.
Paul
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..and I replied:
| Quote: | Paul...How nice to get such a prompt and thoughtful reply...thank you!
> I have a 62" Great American prop which I have tested on my
> Lancair and possibly I could loan that out for testing since I know
> its characteristics.
That's quite an offer! Before I share your email w/ the Europa
community, I wanted to check on the prop mounting/bolt circle; since
you've used it on your 0-235, would that mean it has an SAE 1 bolt
circle? If so, that means it would be a challenge to mount it on a
Rotax, unless someone has an adaptor plate. The guy who's flying w/
Craig's prop does use the SAE 1; however he's flying w/ a Subaru and
claiming (I think) 130 hp. Ideally, for your purposes, I suspect we'd
be best to find someone w/ a Rotax who was game...however, I recall
Craig's strong reluctance to do a prop w/ a Rotax bolt circle due to
pulsing and other serious structural issues.
> A '98 book I have lists the Europa as having a wing area of 95 sq.
> ft. Since drag is pretty much proportional to wing area on clean
> designs such as the Europa and Lancair. I have 125 HP, a wing area of
> 77 sq. ft., and cruise at 201 mph TAS at 10,000' dalt. With equal
> engine power and a retract gear, I would expect your TAS to be
> 201*(77/95)^1/3 or about 187 mph/163 kt. with a high efficiency prop,
> somewhat less with fixed gear.
> Paul
Man...you've got a sweet airplane...and the pixs of your prop are
outta sight.
The published specs and performance #'s for the Europa can be accessed
at
www.europa-aircraft.co.uk/ (click on Specifications). Plane comes as
fixed tri gear or semi-retracted monowheel w/ outriggers. As to your
comparison of wing areas, I've been led to believe that the Europa
airfoil is one of exceptional low drag, worked out by Don Dykins who
put the wings on most of the Airbusses. I don't know off hand what
kind of prop was used for the published #'s but I can find out if
you're interested.
In any event, let me know about your GA prop bolt circle...the 62"
dia. would work just fine. As I said, there's much discussion about
optimal props on the Europa matronics forum...this could get
interesting!
Fred
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This morning Paul confirmed that his 62" Great American prop has an SAE
1,
4 3/8" hole circle.
So here's the opportunity as I see it:
Paul's prop program can generate an optimal FP prop for the Europa if
he can get flight data from a Europa flying w/ a prop with known data;
he is willing to lend such a prop (i.e., 62" Great American prop) to a
Europa flyer who would be willing to generate flight data. I believe
that I'm correct in thinking that extrapolations could be made from
such flight data so that the program could spit out optimally efficient
designs suited for various engines...forgive me, but I'm in this way
over my head.
(w/ regard to the bolt circle issue, SAE 1 vs. the Rotax bolt circle, I
believe adaptors are available.)
Would anyone (whose Europa if flying) be game to give this a go?
Fred
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karelvranken(at)hotmail.c
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| Posted: Wed May 30, 2007 2:06 pm Post subject: Lipps prop for Europa |
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Fred, Gregg and all,
I think that every builder and Europa flyer is interested in the development and research of Paul's propeller. If you don't find someone in the neighbourhood of Paul Lipps, then you may export his 62" propeller to me in Belgium.
Karel Vranken, #447 Mono XS Rotax 912ULS Airmaster CS, only 35 hours so far.
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