Polen Special, anyone?

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Mac790

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I just checked out our archives, and I'm really amazed because we don't have a discussion about such a great plane.

Just a short description for people who haven't heard about that plane before.

Polen Special was designed and built by Mr Dennis Polen, back in 60/70's, first he approached several aircraft manufactures with his design, but all of them rejected it. So he decided to make it by himself, and he did.

Specification:

Engine: Lycoming TSIO-360
Horsepower: 200 hp
Length: 19’6”
Height: 4’10”
Wing Span: 21’5”
Gross Weight: 1,500 lbs.
Max Speed: 345 mph
Cruise Speed: 325 mph
Service Ceiling: 28,000 feet

His design clearly reminds me Busby designs, similarity to the Midget Mustang is obvious (pic1, 2), actually it looks like a enlarged Midget Mustang, with retract gears, wings shape and airfoil are also very similar to the Busby Mustangs. It's really amazing that with only 180/200HP, this plane can cruise at 325 MPH. On the Mr Lednicer web page, I found that airfoil at the root and the tip, is same 65A212, but I haven't found any info about potential wing twist, for example both Busby Mustangs have different airfoil at the root and at the tip (which is rather obvious for tapered wing shape), it confuse me a little bit.

I was wondering, does anyone thought about building something similar to this (Please note it's only theoretical, hypothetical question, I'm aware it won't be an easy task, and it will require some specialist help) , I address this question special to the war-birds fans, for example if I had to chose between building something similar to the Polen or some kind of Mustang, Spitfire replica, I would choose the first one.

I'm aware that this plane probably isn't the most practical plane, it's single person, not enough place for baggage, not enough range for cross country flying unless you live in Europe :), countries here are much smaller.



For more info about this plane
http://www.polenspecial.com/polen_special.htm
or here
Flutter Analysis of the Polen Special II Racing Aircraft Spring 2003



Seb
 

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plncraze

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Mr. Polen wrote a story for Sport Aviation in the early 1970's about the plane. I think it was 1974. There was also a story in Private Pilot and Flying magazines in the 1980's. In Peter Garrison's book "Homebuilt Airplanes" there is half a chapter devoted to the plane.
There were two of the planes started but only one was finished with the other one passing around unfinished. Happy searching!!
 

vortilon

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Always have had a soft spot for that airplane. Alot of Midget Mustang in its lines. Another forgotten airplane is the Dean Delta or Delta Air 250, I believe the EAA has put it back together. I believe I have the spelling right someone correct me if I am wrong. I sure would like to see a picture of it again someday.
 

Topaz

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My recollection is that the original (and the rights) were sold to a third party some years ago. I believe there was brief consideration given to creating kits, but nothing ever came of it that ever crossed my awareness.

I always remember a line from the original Sport Aviation article about this plane regarding the possibility of Polen himself kitting the plane: "Dennis Polen is king of his own kingdom, and he's not about to go handing out crowns."
 

Mac790

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Thanks guys for those magazine titles, I'll try to track them but it won't be easy.

Here is a short movie with a few scenes of the Polen Special in flight, I really like a helmet of the current Polen Special owner (pic1). Note SX-300, in the background.

btw. Has anyone heard about building enlarged version of the existing design (most people build scaled down versions), for example enlarged about 10% Midget Mustang with retract gears, and bigger engine, should have similar specification to the Polen (it's only my assumption:) at this point), but of course a new structural analysis would be required, but it could be a starting point.

Seriously it seems that I have to start reading again (I dropped it about year ago, it's time to say Mr Raymer, and Niu hello:)).



Seb
 

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Topaz

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What boggles and disappoints me is that the video of the 2004 AirVenture Cup Race could just as easily have been the video of the 1994 AirVenture Cup Race. Or, in almost every case in that video, the 1984 AirVenture Cup Race.

We're just not seeing much new development anymore, even in the kit industry. A real shame.
 

bmcj

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I've always been a fan of the Polen Special, but now the Lancair's can match the performance with 2 and 4 seats. I remember reading that Denny Polen thought that the Special required flying skills well above the average pilot and would only consider selling the plane to someone who was highly proficient.
 

Inverted Vantage

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What boggles and disappoints me is that the video of the 2004 AirVenture Cup Race could just as easily have been the video of the 1994 AirVenture Cup Race. Or, in almost every case in that video, the 1984 AirVenture Cup Race.

We're just not seeing much new development anymore, even in the kit industry. A real shame.
Not to mention the music and camera quality could come from 1984. :p
What is it with aviation videos and blaring either bad 80s rock or oldies from the 70s with really grainy, fuzzy home cameras? :p
 

gschuld

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Though I agree that there is nothing specific about the Polen Special that is particularly groundbreaking, the whole package is both efficient and IMHO very attractive. I have spent a bunch of hours studying this plane, a great example of a well designed and constructed 30 year old homebuilt I'd say. Classic lines!





 

wsimpso1

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The Polen Special is really very small. While it is primarily a metal airplane, the current owner acknowledges that the vertical tail is carbon - the original tail fluttered and a much stiffer carbon one was built and installed.

I am sure that in a carbon fiber/glass combination, someone could come up with a faster package wrapped around a turbocharged four cylinder engine, but in a single seater, the market is just too small to be worthwhile. So the focus is on two and four seat airplanes.

Billski
 

autoreply

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I am sure that in a carbon fiber/glass combination, someone could come up with a faster package wrapped around a turbocharged four cylinder engine, but in a single seater, the market is just too small to be worthwhile. So the focus is on two and four seat airplanes.

Billski
I'm often surprised by the lack of attention that's given to the engine drag, usually a standard engine cowl gives a big amount of (cowling) drag. An efficient Jabiru 8-cil (thats 8" or so less wide than a (I)O-360) might cut that even further and then, most people are still less wide than 24", the width of the Jabiru.
 

Mac790

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wsimpso1 said:
I am sure that in a carbon fiber/glass combination, someone could come up with a faster package wrapped around a turbocharged four cylinder engine,
Of course with modern technology, carbon fiber, nomex, autoclave, it could be possible to build lighter plane, with modern CFD software, access to the wind tunnel, it could be possible to build to "clearer" airplane, but Mr. Polen idea was to build rather affordable plane.

but in a single seater, the market is just too small to be worthwhile. So the focus is on two and four seat airplanes.
It's rather obvious if you compare for example RV-6 sales vs RV-3 sales, people prefer also side by side configuration rather than tandems.

autoreply said:
I'm often surprised by the lack of attention that's given to the engine drag, usually a standard engine cowl gives a big amount of (cowling) drag.
Remember that Polen Special was designed back in 60's, show me one experimental airplane from that period with properly designed cowling.

Seb
 
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ghostrider

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I just wanted to bring up the Nexus Mustang in relation to this discussion. Doesnt borrow all that much from the polen other than it being a very clean aircraft.

Being a two seater tandem it is aimed at a slightly larger fraction of the market than the single seaters.

And being a tandem I believe one could minimize the cowling and cooling drag by using a rotary. One could be fitted in a tight cowling making the entire fuselage very slim to reduce drag.

I am also curious about the gear fitted to the polen. Does anyone know if they are salvaged from an existing design or the designers own work?
This gear system would work beautifully on a Nexus provided there is enough headroom structurally in the gear assembly.

Nexus Mustang - by Dick Eaves

Carr Engineered Equipment

Picasa Web Albums - Todd - Nexus #2
 

gschuld

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I am a big fan of trying to examine and learn about the relative performance between high end single engine homebuilt aircraft. Such as the planes of Klaus Savier, Gary Hertzler, Dave Anders, Mike Arnold, Jon Sharp, etc. The Polen special certainly fits in this category. A first glance, the Polen special appears to be groundbreaking with a 315mph speed on a 360 Lycoming. The biggest advantage is obviously in the turbo normalizing system holding that 180hp output in the thinner high altitude air. As stated by the owners, the normally aspirated top end is 240mph at low altitude. Dave Anders, for example has been able to push his highly modified RV-4 into the upper 260s with the same engine, and with a hershey bar wing and room for two people. To be fair, Dave Anders has reported that his engine has been modified to produce over 230hp.

Overall, the Polen Special does seem to be a fine example of the performance gains possible while using the combination of a highly efficient airframe, a turbo normalized engine, and high altitude. From 240mph max at low altitude to 315mph max at 18,000-21,000ft. That's a huge speed percentage gain!



"With the engine normally aspirated, the low altitude max indicated air speed was 210kts (240mph). The cruise speed was approximately the same at 6000-7000ft. The engine is a parallel valve 180hp. 360cu. In. Lycoming. It has been modified with a counter weighted crank shaft, Bendix fuel injector, Kelly Aerospace/Rajay turbo charger, intercooler, gami injectors and a custom Hartzell propeller. The current performance is max level flight speed at sea level of 225kts (259mph). Cruise speed at 15,000-18,000ft is 236kts (270mph) on approximately 10.0gph. The maximum level speed is 274Ktas (315mph) at 18,000-21,000ft with a fuel flow of 20gph. In July 2001 the Polen Special established a new world speed record for the FAI/NAA Class c1b 500km closed course. The old record set by Rich Gritter in a Questair Venture with a 280hp engine, was at a speed of 284mph. The Polen speed for this record was 303.5mph."

This was taken from directly from Dick and Debbie Kent(the current owners)
http://www.hexagonimts.com/index2.php?option=com_content&do_pdf=1&id=20

George​
 
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