On Monday, May 28, 2007, at 06:56 AM, Mike Gregory wrote:
Has anyone tried an Elippse propeller on a Europa? See articlewww.batterso
n.net/EAA499/Issue77_8-13.pdf which makes some interestingpoints about prop
eller 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:
idst of building a Europa XS and your article (www.batterson.net/EAA499/Iss
ue77_8-13.pdf) was brought to my attention in an online Europa discussion o
n optimizing propellers. Thanks for making the esoterica (somewhat) compreh
ensible to a non-techie like myself. Your thinking and design work is aweso
me!..w/ awesome results in efficiency.I noted your ref. to Craig Catto...(C
raig has made one Europa flyer quite happy (Glenn Crowder) and I've had som
e email exchanges w/ him on this topic; I think he is also is doing some fi
ne work...I recall Craig as an audacious 15 yr. old carving his own props w
hen 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 s
tory.Many Europas are flying w/ Warp Drive blades (62" dia.) in an Airmaste
r electric hub and there's general acknowledgment of some shortcomings of t
his arrangement; many are also using FP props. Though the conventional wi
sdom 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 Jabar
u 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 fo
r 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 sundryaircraft, but in order for me to
design a prop for a plane, Ihave to be able to form a drag model of the pl
ane for myequations. The best way to do this is to have one of myprops inst
alled on a plane and then measure the plane=D5sperformance with it. So far
I only have the two props, andthe 2-blade is on loan for a race plane for R
eno. I canform a less-accurate model by measuring the chord andangle of som
eone=D5s prop every inch from the spinner tothe tip and using that data, al
ong with the full-throttle performanceof the plane with that prop to obtain
the dragmodel. This requires the use of a very accurate electronictach, an
d flying the plane around a wide circlewhile measuring GPS-derived ground s
peed and holdinga constant altitude to minimize speed variations. It=D5s al
sohelpful to have a fuel-flow meter in order to determinethe actual install
ed engine horsepower, not the exaggerationsof some of the engine-makers!I w
ould be happy to attempt to generate the info and data which you would need
.Fred
Paul Lipps replied:> Hi, Fred!
> 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
...and I replied:
> 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
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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