Today's Message Index:
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1. 05:02 AM - On Blended airfoil prop (mppalmer@aol.com)
2. 10:13 AM - Re: On Blended airfoil prop (Craymondw@aol.com)
Message 1
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| Subject: | On Blended airfoil prop |
Wow, a 20 mph gain is impressive! Seems like Hartzell has got it
figured out. (Too bad they don't make such a prop for the lowly O-320.)
In addition to a quieter ride, I bet your engine cooling is better too.
You might be able to close down the inlets later and get a few more
knots. (Whereas, with our Hartzell prop, with its big, round roots, I
never noticed a difference in speed by reducing the inlets. I suspect
the drag from the prop roots is the bigger factor, per Paul Lipps.)
Now, if only Glasair would re-loft the airframe on a PC and tweak the
fiberglass to reduce drag...
>My indicated airspeed using my old Hartzell averaged around 163 mph
at those settings
>at those altitudes. Using my new blended foil design, I noted
indicated airspeed of 185 mph.
Mike Palmer <><
Message 2
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| Subject: | Re: On Blended airfoil prop |
Mike Palmer,
Don't jump the gun yet, this was only my first flight with our new
blended foil prop and the Sky Gods may have had the atmosphere in perfect
order. Depending on atmospheric conditions we have recorded a wide range of
cruising speeds in the past. It will take several flights in different
atmospheric conditions to verify if the prop added a full 20 mph to my cruise.
My gut tells me it has. As far as cooling, I closed up the cowling inlets
several years ago. And contrary to what one would surmise with this new
prop, our engine didn't run cooler but instead ran a little hotter. The only
two things I can surmise is that the engine is actually working and
pulling harder with the blended foil or because of the faster speed the tail is
up higher disturbing the air in the inlets. When Deborah competed in the
1994 Sun and Fun Race she averaged around 220 mph with all knobs full forward.
But at altitude we found we get our best speeds around 2400 rpm. I think
in the thinner air our old prop just created prop turbulence at higher
RPM's. Before I added the blended foil prop I took Ken Johnson's advice and
closed up our cowl side mounted injector inlet by almost three inches and our
cooling inlets by an inch. Note: If you do that, remember to bring the
lower section forward or you create an air dam! Dropping plumb lines off the
fuse center line and drawing parallel caulk lines on her hanger floor and
realigning the wheel pants gave us a big jump in speed. Our next big increase
was removing the 2 degree droop out of her flaps and filing a notch in the
fairing so we could slightly reflex the flaps. That gave us another jump in
cruise speed. After a nose wheel failure in 1996, I disassembled the
plane and put it on a diet and removed well over 100 pounds. The first paint
was a heavy Centuri over a heavy lacquer primer. I shaved and sanded
everything off and placed the debris into plastic garbage bags and weighed them.
They came out to 45 pounds!! After that I sanded the jell coat almost to
the fiber glass and primed it with a light weight epoxy primer and finished
it off with an ultra light Pittsburgh, base coat, pearl coat and top coat
system. I placed in a light weight starter, a set of lighter Slick mags and a
light weight battery and light weight upholstery.
Before I built Deborah's Glasair, she owned a T-18 that cruised around
170 mph on a tricked out 320 Lyc. The first flights on Deborah's Glasair
only produced a cruise speed of around 190 mph and we wanted to strangle Ted
Setzer when he advertised 225 mph to 235 mph cruise speeds. It took a lot
of tweaking over the years to get up to 205/210 mph cruise speed she now has
on her Glasair. Even with that, we always felt the Glasair was far capable
of greater speeds because on long descents from altitude we would commonly
see 225 to 235 speeds and felt it was the prop. This was verified when we
met up with a Glasar 2 FT driver that opted out of a Hartzell for a
McCauley prop having cruise speeds over 220 mph.
Charles Raymond
message dated 2/10/2010 8:02:32 A.M. Eastern Standard Time,
mppalmer@aol.com writes:
--> Glasair-List message posted by: mppalmer@aol.com
Wow, a 20 mph gain is impressive! Seems like Hartzell has got it
figured out. (Too bad they don't make such a prop for the lowly O-320.)
In addition to a quieter ride, I bet your engine cooling is better too.
You might be able to close down the inlets later and get a few more
knots. (Whereas, with our Hartzell prop, with its big, round roots, I
never noticed a difference in speed by reducing the inlets. I suspect
the drag from the prop roots is the bigger factor, per Paul Lipps.)
Now, if only Glasair would re-loft the airframe on a PC and tweak the
fiberglass to reduce drag...
>My indicated airspeed using my old Hartzell averaged around 163 mph
at those settings
>at those altitudes. Using my new blended foil design, I noted
indicated airspeed of 185 mph.
Mike Palmer <><
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