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P-51C at ~70% scale as ultralight?

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12notes

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With all that familiarity with the UC .Can you confirm that the wing area would perform to the 28 mph. power off stall and max speed level flight full throttle of 60 mph. ,that's required to make 103
I'm not that familiar with it, I've read some owner information, and here have only used random pictures and the information at the Hummel website. The top speed is limited by a lower rev limit to keep it under 62mph, the non ultralight version uses the same engine. The stall speed, you'd need to talk to someone who flies one, but I think it does meet the requirement.
 

BBerson

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It looks to me the Ultracruiser with the 25 foot original wing can just meet AC 103-7 criteria. It doesn't need to actually stall at 28 mph if the criteria formula is met. It has flaps and 110 sq.ft and a thick high lift airfoil to meet the criteria.
I don't think the 25 foot spar is as strong, so most go with 22 feet and apparently no one cares.
If you weigh only 130 like Morry then go with the 25 foot wing, no problem.
 

Norm Langlois

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Since I designed,built and flew ,As well blogged both here and in EAA's forums. I learned by way of the community of said incident. Where an individual crossed paths with the FAA rep and was put through the wringer. Not being a historian I didn't record the who or when. I only cared That I not be to out front by entering in judging without being pretty sure it was compliant.
That is why I haven't taken it to Osh 2018 it was over weight ,and now its not ever going there . I have made it compliant but only barely.
Just being at the lake prepping always attracts attention. Keeping a low profile is not easy. Building for Expo will not be ether. How will you avoid the scrutiny, That will inevitably roll the dice against you .
I brought my plane to a local fly in where there was a FAA rep there, doing a forum. He scowled at me and my plane . Another had to remind him I was using the additional weight exemption afforded to a seaplane.
If anyone builds a plane and shows it off.That which you don't want may come your way. If your going to stretch the limits . You may want to keep it to yourself way out of sight.

The FAA does avoid 103 . Yes but for how long. The LSA came along many hoped it would end the 103 era. by elimination of training.
The 103 is still the most fluid venue to build with .It has no rule book only the final creation must be compliant. to weight and flight character.
 

cluttonfred

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VB's skepticism and JLF's orneriness aside, here is quick sketch of what the proportions of a Part 103 Mustang Lite might be. You can see that it would look cartoonish because of the grossly different proportions between the pilot and engine weight and the big tail surfaces required by the low speeds but it could still be fun. I took the Sky Pup as a realistic Part 103 starting point and I could see a single base design evolving with the same basic structure and just cosmetic changes to vaguely resemble different WWII designs.

part 103 p-51.jpg

Oh, "sense"? You want this idea to make sense? Oh, my dear dear friend, sit down for a minute, I have some really bad news for you...
 

J.L. Frusha

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VB's skepticism and JLF's orneriness aside, here is quick sketch of what the proportions of a Part 103 Mustang Lite might be. You can see that it would look cartoonish because of the grossly different proportions between the pilot and engine weight and the big tail surfaces required by the low speeds but it could still be fun. I took the Sky Pup as a realistic Part 103 starting point and I could see a single base design evolving with the same basic structure and just cosmetic changes to vaguely resemble different WWII designs.

View attachment 84900
Not knowing enough, how would that work out on the cartoon-scale version? I've taken a liking to the overall appearance of what I've started calling the Shetland Pony...
 
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pictsidhe

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Lengthen the tail, shorten the nose and find a light engine. If you have a p51-esque wing planform and radiator scoop, it'll look about right. Especially once you paint it.
 

J.L. Frusha

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Lengthen the tail, shorten the nose and find a light engine. If you have a p51-esque wing planform and radiator scoop, it'll look about right. Especially once you paint it.
Figuring on something like a 1/2 VW for power at ~30hp, though I'm no familiar with the weight.

I have contaced a couple of rc modelers toward getting help modeling it in a flying version to get a better feel for how it will behave.
 

J.L. Frusha

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Maybe more something like one of these...? (no idea of the cost)




630Hs

52HP BOXER UAV ENGINE WITH ELECTRONIC INJECTION 100A BRUSHLESS STARTER / GENERATOR
Engine
630H
Type opposed two cylinder two stroke boxer
Output 52HP at 6500 rev/min
Total Displacement 630 cm3
Cooling System air > 25 m/sec
Bore 76 mm
Stroke 56 mm
Compression ratio 10,6:1
Cylinders light alloy metal ceramic plated castings
Cylinder heads aluminum alloy
Crankcase light alloy lost wax castings
Crankshaft forget steel supported by special double-row ball bearings
Fuel metering fuel injection in the intake manifold
Ignition system double programmed inductive discharging system managed by ECU
Exhaust system Mufflers
TBO 1000 hours with scheduled maintenance
Communication from ECU to client system by RS232
Operating temperature -20 +65°C
Alternator
Brushless 28V-100A

Rotation counter clockwise (looking from the propeller side)
Fuel
=> 95 Oct. petrol/oil mixture 2% syhthetic oil for 2 stroke engines

Weight with Alternator 18,6Kg
Specific consumption better than 310gr/HP/h
Redundancy Double ignition and double pick-up and double TPS
Autorecovery Throttle body and pick-up
 

J.L. Frusha

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My best approximation of Ultracruiser vs my P-51 'Shetland Pony' idea.

*note: Pilot figure has full headgear, so clearance inside Hummel would be a bit more w/o it, as indicated in pics of the Ultracruiser I find online

 
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Saville

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You could start with an RV-8 and add a belly scoop and see what you end up with. Then make other modes - maybe an inline engine.
 

radfordc

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You could start with an RV-8 and add a belly scoop and see what you end up with. Then make other modes - maybe an inline engine.
Do you think that would work as an ultralight? I'm guessing it would be about a 1000 lbs too heavy!
 

J.L. Frusha

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I promise you that Dick VanGrunsven would vigorously object to that characterization of his design.


BJC
[/QUOTE]
He might and I'd let him, but the profiles are similar enough. ALL of the sport Mustangs are at least loosely shaped from the North American P-51s...
 

BBerson

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The tail moment arm and areas need to be adequate for ultralight speeds. Should be designed for spin recovery. The cartoonish cockpit is good, and should not effect the needed tail length.
 
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