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

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by J.L. Frusha, Apr 30, 2019.

Help Support HomeBuiltAirplanes Forum by donating:

  1. May 9, 2019 #81

    Victor Bravo

    Victor Bravo

    Victor Bravo

    Well-Known Member

    Joined:
    Jul 30, 2014
    Messages:
    5,803
    Likes Received:
    4,649
    Location:
    KWHP, Los Angeles CA, USA
    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...
     
  2. May 9, 2019 #82

    12notes

    12notes

    12notes

    Well-Known Member Lifetime Supporter

    Joined:
    Aug 27, 2014
    Messages:
    718
    Likes Received:
    459
    Location:
    Louisville, KY
    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.
     
  3. May 9, 2019 #83

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    6,128
    Likes Received:
    1,571
    Location:
    North Carolina
    Since when are our dreams and actual toys supposed to make sense?
     
  4. May 9, 2019 #84

    BBerson

    BBerson

    BBerson

    Well-Known Member HBA Supporter

    Joined:
    Dec 16, 2007
    Messages:
    11,523
    Likes Received:
    2,138
    Location:
    Port Townsend WA
    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.
     
  5. May 9, 2019 #85

    Norm Langlois

    Norm Langlois

    Norm Langlois

    Well-Known Member

    Joined:
    Dec 14, 2011
    Messages:
    206
    Likes Received:
    122
    Location:
    Northwood NH USA
    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.
     
  6. May 9, 2019 #86

    cluttonfred

    cluttonfred

    cluttonfred

    Well-Known Member

    Joined:
    Feb 13, 2010
    Messages:
    6,350
    Likes Received:
    2,214
    Location:
    World traveler
    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

     
    J.L. Frusha likes this.
  7. May 9, 2019 #87

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    6,128
    Likes Received:
    1,571
    Location:
    North Carolina
    The nose on my Hurricane is too long, the tail too short. Balance is an issue. The 51 is much worse...
     
  8. May 19, 2019 #88

    J.L. Frusha

    J.L. Frusha

    J.L. Frusha

    Well-Known Member

    Joined:
    Feb 17, 2006
    Messages:
    113
    Likes Received:
    5
    Location:
    Kingsbury, Texas
    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...[​IMG]
     
    Last edited: May 19, 2019
  9. May 19, 2019 #89

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    6,128
    Likes Received:
    1,571
    Location:
    North Carolina
    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.
     
  10. May 19, 2019 #90

    J.L. Frusha

    J.L. Frusha

    J.L. Frusha

    Well-Known Member

    Joined:
    Feb 17, 2006
    Messages:
    113
    Likes Received:
    5
    Location:
    Kingsbury, Texas
    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.
     
  11. May 19, 2019 #91

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    6,128
    Likes Received:
    1,571
    Location:
    North Carolina
    they aren't light engines. It would need a very short nose.
     
  12. May 19, 2019 #92

    radfordc

    radfordc

    radfordc

    Well-Known Member

    Joined:
    Feb 5, 2008
    Messages:
    1,170
    Likes Received:
    443
    FWF, about 90-95 lbs depending on prop and motor mount.
     
  13. May 19, 2019 #93

    J.L. Frusha

    J.L. Frusha

    J.L. Frusha

    Well-Known Member

    Joined:
    Feb 17, 2006
    Messages:
    113
    Likes Received:
    5
    Location:
    Kingsbury, Texas
    Maybe more something like one of these...? (no idea of the cost)

    [​IMG]


    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
     
  14. May 19, 2019 #94

    J.L. Frusha

    J.L. Frusha

    J.L. Frusha

    Well-Known Member

    Joined:
    Feb 17, 2006
    Messages:
    113
    Likes Received:
    5
    Location:
    Kingsbury, Texas
    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

    [​IMG]
     
    Last edited: May 19, 2019
  15. May 19, 2019 #95

    Saville

    Saville

    Saville

    Active Member

    Joined:
    Apr 28, 2014
    Messages:
    43
    Likes Received:
    5
    Location:
    Boston Ma
    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.
     
  16. May 19, 2019 #96

    radfordc

    radfordc

    radfordc

    Well-Known Member

    Joined:
    Feb 5, 2008
    Messages:
    1,170
    Likes Received:
    443
    Do you think that would work as an ultralight? I'm guessing it would be about a 1000 lbs too heavy!
     
  17. May 19, 2019 #97

    J.L. Frusha

    J.L. Frusha

    J.L. Frusha

    Well-Known Member

    Joined:
    Feb 17, 2006
    Messages:
    113
    Likes Received:
    5
    Location:
    Kingsbury, Texas
    Even the RV-3 is roughly 500 lbs excessive, though the series is loosely based off the Mustang II sports planes.
     
  18. May 19, 2019 #98

    BJC

    BJC

    BJC

    Well-Known Member

    Joined:
    Oct 7, 2013
    Messages:
    9,076
    Likes Received:
    5,884
    Location:
    97FL, Florida, USA
    I promise you that Dick VanGrunsven would vigorously object to that characterization of his design.


    BJC
     
    Last edited: May 19, 2019
    pictsidhe likes this.
  19. May 19, 2019 #99

    J.L. Frusha

    J.L. Frusha

    J.L. Frusha

    Well-Known Member

    Joined:
    Feb 17, 2006
    Messages:
    113
    Likes Received:
    5
    Location:
    Kingsbury, Texas
    [/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...[​IMG]
     
  20. May 19, 2019 #100

    BBerson

    BBerson

    BBerson

    Well-Known Member HBA Supporter

    Joined:
    Dec 16, 2007
    Messages:
    11,523
    Likes Received:
    2,138
    Location:
    Port Townsend WA
    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.
     
    J.L. Frusha likes this.

Share This Page

arrow_white