Polen Special, anyone?

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mike_t_12

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airport_2_small.jpgairport_3_small.jpgairport_4_small.jpgairport_5_small.jpg

Here are a few more renders. I added stripes and some decals but it took a lot longer than expected to figure out how to do it. I wanted to learn how to do the stripes/decals since it's the last step in the modeling/rendering process.
 

mike_t_12

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airport_1_small.jpgairport_2_small.jpgsunset_5_small.jpg

A few more renders - I redid the stripes and made them a little skinnier. This is about it for version 4... Now working on version 5 - need to figure out how to turn the bits and pixels into something more real.
Mike
 

Devin York

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Crediton Ontario Canada
Gary!

I am a builder just getting into the Nexus
I used to work with Dick and his son Chris at XU

Learned alot from them and now work as a professor in aircraft structures.. I am interested in contacting the individual doing the mods to see what he has to say and possibly obtain some info

Can you send me his contact? my email is

yorkdevin@gmail.com
 

mike_t_12

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Hi All,

It's been a long time (too long) since I've updated my progress but finally finished version 5. In the pictures, you can see that it departs significantly from the 3-view of the original Polen Special. Version 5 is more of a Polen Special inspired design as opposed to a copy of the original Polen Special. Also, still very much conceptual but more realistic in terms of size (version 4 was a tight fit) for the engine and a 6' 3" pilot. There's about 2 inches of headroom and 6 inches under the seat. I want to do something for safety (crush zone) under the seat but still need to learn more about this.

I have Dan Raymer's "Simplified Aircraft Design for Homebuilders" and have been using the Excel spreadsheet. Tracing through the cells for the various formulas is kind of painful so I used this as an excuse to start learning a math package. I have most of the equations from Raymer's book entered into a Mathematica notebook and making some progress with the initial numbers.

I feel like I've made some good progress but realize I've barely scratched the surface! More to follow.

Mike

1 Pollen special 3 view - with text - small.jpg2 V5 side view 1 small.jpg3 V5 side view 2 small.jpg4 V5 side view 3 small.jpg5 V5 side view 4 small.jpg6 V5 perspective 1 small.jpg7 V5 perspective 2 small.jpg8 V5 perspective 3 small.jpg9 V5 perspective 4 small.jpg
 

mike_t_12

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Hi All,

Checking in with some updates. I'm mostly finished with Raymer's "Simplified Aircraft Design for Homebuilders." I learned a lot and definitely recommend it as a 1st step for anyone without experience and doing a conceptual design. Per the book, it's meant to be a first-pass conceptual design so I think it gives you a "gentle" introduction to aircraft design. The accompanying Excel spreadsheet (free from Dan Raymer's website) is very helpful and lets you do sample calculations as you work your way through the book.

From the Raymer spreadsheet, some of my version 5 numbers are -

Gross weight: approximately 1650 lbs
Engine: 200 hp (Turbocharged)
Range: approximately 890 nmi
Stall: 60 kts
Cruise: 220 kts
Ceiling: 22,000 ft.
Power Loading: 8.25
Wing Span: 22.5 ft.
Root Chord: 4.7 ft
Tip Chord: 2.8 ft
Wing area: 84.4 ft
Wing taper ratio: .6
Wing Loading: 19.6 psf
Fuel: 44 gallons
Wing: NACA 65-212
Elevator and Rudder: NACA 0012
Pilot: 6' 3" and 225 lbs

I don't have a lot of confidence in the weight estimates or CG estimates for the various components so I'm sure there will be a version 6 in the future.

I've updated version 5 per the spreadsheet numbers - for safety purposes, there's about 6 inches of space below the seat and 2 inches of headroom to the canopy. The wings, elevator and rudder are modeled as the airfoils listed above and are in approximately the right locations for CG considerations. Also, the elevator was moved forward to help with spin recovery.

I feel like I've made a lot of progress but realize it's just the tip of the iceberg - on to version 6!

Mike

v5_1_side_1.jpgv5_2_side_2.jpgv5_3_cockpit_space.jpgv5_4_45_degree_1.jpgv5_5_45_degree_2.jpgv5_6_side_3.jpgv5_7_side_4.jpg
 

BJC

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Nice. Glad that the project continues.

Does the original use the 0012 airfoil for the tail? I would have guessed something closer to a 0009.

Enlarging the fuselage should make more room for the retractable gear, which is very crowded in the Polen Special.

Your specs seem to infer travel at high altitudes. Do you plan on a permanently installed oxygen system?


BJC
 

mike_t_12

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I'm not sure about the original tail surfaces. I picked the 0012 after reading Barnaby Wainfan's "Airfoil Selection" book. He mentioned that the 0009 and 0012 as good choices for tail surfaces but I didn't have any specific reason for picking the 0012 over the 0009.

I haven't thought about a permanent oxygen system but it seems like a good idea... not sure what the pros and cons are.

Mike
 

DangerZone

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Zagreb HR
I'm not sure about the original tail surfaces. I picked the 0012 after reading Barnaby Wainfan's "Airfoil Selection" book. He mentioned that the 0009 and 0012 as good choices for tail surfaces but I didn't have any specific reason for picking the 0012 over the 0009.

I haven't thought about a permanent oxygen system but it seems like a good idea... not sure what the pros and cons are.

Mike
Pros: you'd be able to breathe longer without passing out when flying above 12k ft, good for long range flights.
Cons: added weight, cost of used systems.
DSCN9076A_600w.JPG

On such a nice and fast airplane, it would be wise to have a turbo charger for the engine and an oxygen system for the pilot.
 

mike_t_12

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I finally had a chance to do some renders of version 5. I know the color pics aren't necessary at this point but it helps with visualizing the end goal and keeps me motivated.

I looked into built-in oxygen systems... It seems like a good idea but for the moment, will probably just go with a portable system.

I have some time off at the end of the year so will be spending some more time on this. Next up, I'd like to get the EAA/Solidworks installed and try importing my surface model (as a .obj format, I guess). I'd also like to do some modeling of the interior. More to follow soon.

Mike
 

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mike_t_12

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Hi All,

I made a little progress on the interior. Nothing final, just wanted to get an idea of size and space. I started to model some of the instruments but decided to stop for now. I've been working a lot of extra hours this year so I haven't been able to work on this as much as I'd like. I'm going to do a model of the landing gear next so I can do some renders while on the ground.

Mike
 

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David Moxley

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Here what I’m working on. Been working away at it finally,after several years of it being in storage! Making progress again. Will be coming out of jig soon.
Dose anyone know the Whereabouts of the 2nd: special that Darrell Usher started?He sold it serval years ago I heard to a person in Arizona? The last I heard the project was sold to someone in California? I’m sure there’s someone out there that belongs to an EAA chapter that knows where it’s at ? Any information would be greatly appreciated
 

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VP1

Todd C.
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I was looking at your project thread suspiciously titled ‘special’ and couldn’t think of a ‘modern’ aluminum single seater with such a high turtle deck..other than the Polen.. no? Could it be??
Did a little sleuthing and sure enough.
I figure more people would like to know what you’re building.
 

David Moxley

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I was looking at your project thread suspiciously titled ‘special’ and couldn’t think of a ‘modern’ aluminum single seater with such a high turtle deck..other than the Polen.. no? Could it be??
Did a little sleuthing and sure enough.
I figure more people would like to know what you’re building.
Hello Todd.
Tailcone is a slightly lengthen Midget Mustang , the turtle deck is no higher than a Midget, firewall is in the shape of a PA-30 twin Comanche, all the bulkheads & firewall I built . Bulkhead are 0.40 , skins are 0.32 everything is flush riveted.
It will be a Close copy to the Polen , this
is what I’m after. Many years ago I was the first person to show-up when it was put up for sale in Troutdale Oregon. I met with the man , Randy Francis handling the sale of it for Dennis , Dennis was unable to make it to the airport that day ,do to a doctors appointment, wish I could have met him. I looked long & hard at it , took a lot of pictures , and video of it, sat in it, got a good idea how it was build. Almost pulled the trigger buying it, thought long , and hard. Just couldn’t see the money they were asking for it, I understand it is a legendary Aircraft with a lot of mystery , Dennis kept it that way, but I passed on it , the next person in line was Richard Keyt, he bought it. He has had his problems with it, landing gear, and flutter, I thing it has been on the ground 2 or 3 times do to the landing not coming down?, and the rudder almost came off ! But he has stuck with it, and made a lot of improvements over the years to the aircraft. Prior to all this I was talking to Darrell Usher about a wing rib I need for my Mustang II I had at the time, and told him I wanted to build a Midget Mustang with a IO-360, 200 hp. He told me he had a project that was similar to a Midget Mustang that used to 200 hp engine, and was a fully retractable gear that he would sell me. He didn’t tell me what it was, but was describing the second Polen, that he was building,he described it to me to the tee ! If I would have only know! It was sold ,and has changed hand a couple of its, don’t know were it’s at ? I have owned 2 flying Midgets , and a Johnny Thompson copy Tri-gear retractable Mustang II that I bought in Tucson Arizona from the builder that I flew for 25 years, sold it after I finish build a Dave Ander clone hot rod RV-4 that is very fast, Ly-con built XIO-390 that made 250hp on the dyno at 2700 rpm.It has Rocket fuel tanks, and if your butt can take it you can go a long way. I swore when I finish the RV that was it for building! But here I am beating away on this project that I started over 15 years ago. That’s were it at for now, I try to go down to the hanger as much a possible to work on it as I can. I’m at the point now that I need to build the main spar center section , so I can get the fuselage out of the jig, that will be a huge task. I will be adding photos as I progress a long.
Here are a few pictures of the RV-4CC33D88C-819F-43BD-82D1-07D312394DA4.jpeg4841A51B-6C00-4FC7-8F1C-1B5CA933B850.jpeg B1DAB5D7-263C-48C3-A4F7-AE6212DF2FCE.jpeg
 
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BJC

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That is a fine project; the Polen Special is the best looking HBA of all time. I will follow your build with great interest. Hopefully, you will have a build thread here, with lots of photographs.

A few questions:

The original LG retract system seemed overly complicated, and the available internal space was marginal. Will yours have retracts, or fixed?

The original was intended for high altitude cruising. Same for your’s, or will your’s be more of a sport airplane?

After the rudder flutter, IIRC, Dick had a ground vibration test of, at least, the wing. Has he shared that info with you, and, if so, does it indicate that a design change is needed?

The one angle valve 200 HP Lycoming MM that I saw years ago had lots of lead in the tail, and had limited fuel for CC. I saw that your’s will be longer. Where, and how much fuel will you have?

Thanks,


BJC
 

David Moxley

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Hello BJC
Landing gear will be retractable, and I’m aware of the limited space. It’s not impossible, just another challenge to make it work correctly. Build a airplane is solving a series of problems at sometime do you want to pull your last good hair out!!
It will be for high altitude, nothing like getting up high and going fast!
I have never spoken to Richard Kyte. I’m aware of the vibration test he had done on the aircraft, have read about it. I would like to meet him, and see the airplane again.
I plan on making all the control surfaces out of carbon fiber. There are some very talented people here at the airport KCOE one of them being Burt Rutan, and Murdo Cameron. There is a wealth of composite knowledge here!
I have seen the Midget Mustang with the 200 horse angular valve engine in it . Of course they had to put a lot of lead in the tail with that engine. It must have been a after thought? The should have lengthen the tailcone to help solve that problem. I have a M20M TLS and it has lead in the tail because of the TIO-540 in it. I don’t think mine is going to be much longer, if any. The original has fuel in the center section on either side of the pilot behind the main spar. Plan on doing that , and the outboard wings leading edge . My Mustang II was like this, it held 68 gallon if my memory serves me right. I flew it from Fresno Ca. to Enid Oklahoma without stopping. I could hardly get up out of it.
Here a picture of my MII , it was a fun airplane to fly. Only had it on the ground one time do to the right hand main scissors Breaking !But that’s another story.
I have a post under member project log , That’s were I post my progress. 6F6E08E1-C3ED-4458-94B7-16B66100E0AB.jpeg
 
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David Moxley

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D27FA6F1-FA27-4E6C-BEDB-DA5D43A771D4.jpeg 3119A392-CDC0-4CDF-B0EB-BDA1CA54548F.jpeg 8947778D-9668-4BDD-BC14-BF9A55ACB907.jpeg A10F6FCB-9080-4F57-9915-ECC5308AEDD0.png E267731E-D27A-41A7-8EC6-E67FB7CAD912.jpeg D3685DE4-AA3C-43B2-B695-96B47378BDCD.jpeg BBC0A41D-CAED-464F-9EFD-27662F48D1B7.jpeg E050D043-D836-4A15-9EA5-772086906C7C.jpeg D27FA6F1-FA27-4E6C-BEDB-DA5D43A771D4.jpeg 3119A392-CDC0-4CDF-B0EB-BDA1CA54548F.jpeg 8947778D-9668-4BDD-BC14-BF9A55ACB907.jpeg A10F6FCB-9080-4F57-9915-ECC5308AEDD0.png E267731E-D27A-41A7-8EC6-E67FB7CAD912.jpeg The last couple of weeks I have been busy laying out the center section and outer wing panels. Started out working on the floor, that got old fast! So I built a table that is 23 feet long in a day. About killed me off, but it done. Order all the materials needed to build the center section & outer wings . Going to get busy when the material arrive. The day before the Table I built a 8 foot sheet-metal brake , saw this on the EAA website. The sample from right to left, right no set back, middle,1/8” set back, left 1/4” set back. Happy with the results. Cost about $350 in Materials , hardest part was drilling the stainless steel hinge.
 
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thjakits

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Hi David,

excuse my ignorance:

I know what a sheet-metal brake is and how it - usually - works. In the pictures posted I see a continous piano hinge...

HOW does THIS brake work??

Cheers,
thjakits
 
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