More of my random designs

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Sockmonkey, Jul 12, 2019.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Jul 12, 2019 #1

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    For fun I decided to mess around with a small passenger/cargo plane design.
    Not just neat looking, it's based on specific traits I wanted to include.
    [​IMG]

    Twin engine redundancy without serious off-axis problems if one fails means a lot of design compromises to make it push-pull or the fiddly bits of a co-axial.
    A pair of pullers close together is the next best thing.
    That means the fuselage can't protrude ahead of the wing, which shifts the CG back, which means it has to be a tandem wing.
    Tandem wings have advantages of their own, so it seemed a better compromise.
    Aside from the high lifting capacity it also accommodates clamshell doors at the tail for easy loading.
    The aft wing has a single flap to adjust trim to account for load variances.
    The front wing has "flapelevons" for takeoff, roll, and climb.
    Made the aft wing a high delta for dihedral effect and the additional directional stability, plus big twin rudders.
    Engines are a pair of liquid cooled inline sixes.
     
    Battler Britton, Arfang and bmcj like this.
  2. Jul 12, 2019 #2

    bmcj

    bmcj

    bmcj

    Well-Known Member HBA Supporter

    Joined:
    Apr 10, 2007
    Messages:
    12,736
    Likes Received:
    4,725
    Location:
    Fresno, California
    Unique enough that it’s hard not to like it.

    Obviously a taildragger though?
     
  3. Jul 12, 2019 #3

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    Yup. Aside from using the rear of the engine nacelles to house the main gear, it's convenient to have the aft loading door close to the ground.
    Oh, forgot to mention the small window in the forward floor of the cockpit for landing visibility.
    I think I've covered the bases in that there don't seem to be any dealbreakers AFAIK.
     
  4. Jul 12, 2019 #4

    ScaleBirdsScott

    ScaleBirdsScott

    ScaleBirdsScott

    Well-Known Member

    Joined:
    Feb 10, 2015
    Messages:
    953
    Likes Received:
    611
    Location:
    Uncasville, CT
    Pretty neat, and I like that it was all explained out and seems to make sense. Would it have a single tailwheel, or a pair of tailwheels to either side of a loading door? I don't know what it would be like to control such a beast, but if they were full caster and used differential brake steering up front I guess it'd work?
     
  5. Jul 12, 2019 #5

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    I was thinking single tailwheel, but two might be better. It would steer like a standard taildragger.
     
  6. Jul 12, 2019 #6

    Doggzilla

    Doggzilla

    Doggzilla

    Well-Known Member

    Joined:
    Jun 2, 2013
    Messages:
    1,766
    Likes Received:
    353
    Location:
    Everywhere USA
    Interesting design but it would actually have some stability issues.

    The rear wing will stall first and is in the wake of the front wing during stall, making it even worse.

    With the CG between the wings and with the rear wing stalled first it would tumble backwards during a stall.
     
  7. Jul 12, 2019 #7

    Arfang

    Arfang

    Arfang

    Well-Known Member

    Joined:
    Aug 10, 2014
    Messages:
    89
    Likes Received:
    75
    Location:
    Switzerland
    Nice, very Payen-looking design. Is that a civilian version of his model P.321?

    payen_pa321_1.jpg
     
    Sockmonkey likes this.
  8. Jul 12, 2019 #8

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    Why would the rear wing stall first? The fore wing is has the higher area loading. Plus the leading edge of the aft wing sweeps back at 55 degrees.
    Very cool. Came up with it independently, but probably by the same reasoning
     
  9. Jul 12, 2019 #9

    Doggzilla

    Doggzilla

    Doggzilla

    Well-Known Member

    Joined:
    Jun 2, 2013
    Messages:
    1,766
    Likes Received:
    353
    Location:
    Everywhere USA
    Stall is about the angle. Swept wings stall at lower angles due to lateral flow. Since they are both at very similar angles the rear swept wing will always hit its lower stall angle first.

    And having it behind and above causes “deep stalls”. This is why aircraft don’t use T tails very often anymore.
     
  10. Jul 12, 2019 #10

    bmcj

    bmcj

    bmcj

    Well-Known Member HBA Supporter

    Joined:
    Apr 10, 2007
    Messages:
    12,736
    Likes Received:
    4,725
    Location:
    Fresno, California
    Low aspect ratio wings have a higher stall angle, and the high LE sweep of deltas in particular can drive vortex formation above the wing and delay the stall even further. Watch some videos of deltas landing and you will see some ridiculously high nose angles at touchdown. That is one of the reasons the Concorde had a droop nose cone.
     
    Dart likes this.
  11. Jul 12, 2019 #11

    Doggzilla

    Doggzilla

    Doggzilla

    Well-Known Member

    Joined:
    Jun 2, 2013
    Messages:
    1,766
    Likes Received:
    353
    Location:
    Everywhere USA
    That’s a common belief but not so.

    Delta aircraft require high angles of attack to produce the same lift at low speed, that does not give them superior stall angle. If they come in at normal angles the sink rate is unsafe. Basically like landing on an aircraft carrier.

    Any other airliner could do the very same thing, but it would be at a much lower airspeed before they required such a high angle of attack.

    There is a reason nobody uses Deltas without canards anymore.
     
    Dart likes this.
  12. Jul 12, 2019 #12

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    As in canards for improving the airflow over the delta yes?
    So are we wanting to switch to a straight rear wing?
     
  13. Jul 12, 2019 #13

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    6,441
    Likes Received:
    1,672
    Location:
    North Carolina
    Rubbish
     
    Andy_RR and Dart like this.
  14. Jul 12, 2019 #14

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    *shrug* Better?
    [​IMG]
     
    Battler Britton and Dart like this.
  15. Jul 13, 2019 #15

    Doggzilla

    Doggzilla

    Doggzilla

    Well-Known Member

    Joined:
    Jun 2, 2013
    Messages:
    1,766
    Likes Received:
    353
    Location:
    Everywhere USA
    Just because I won’t indulge an unsafe fantasy doesn’t mean I am talking “Rubbish”.

    That kind of attitude already got two people killed after they ignored my warnings.

    Im going to listen to the chief engineer of the Concorde over random people on the internet.
     
  16. Jul 13, 2019 #16

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    Using a straight rear wing, it should be stall-proof as long as the fore wing is set at a higher AOA and it's not overloaded.
    There's also this fellow, but he's not as pretty.
    [​IMG]
     
  17. Jul 13, 2019 #17

    Victor Bravo

    Victor Bravo

    Victor Bravo

    Well-Known Member

    Joined:
    Jul 30, 2014
    Messages:
    5,890
    Likes Received:
    4,712
    Location:
    KWHP, Los Angeles CA, USA
    Sockmonkey, you're the Norman BelGeddes of 2019 !
     
    Sockmonkey and Tiger Tim like this.
  18. Jul 13, 2019 #18

    Sockmonkey

    Sockmonkey

    Sockmonkey

    Well-Known Member

    Joined:
    Apr 24, 2014
    Messages:
    1,650
    Likes Received:
    430
    Location:
    Flint, Mi, USA
    Well...
    [​IMG]
    Maybe...
     
  19. Jul 13, 2019 #19

    ScaleBirdsPaul

    ScaleBirdsPaul

    ScaleBirdsPaul

    Member

    Joined:
    Jul 6, 2015
    Messages:
    16
    Likes Received:
    11
    Location:
    Connecticut
    Wow. On pure style, I love this.
     
    Sockmonkey likes this.
  20. Jul 13, 2019 #20

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    6,441
    Likes Received:
    1,672
    Location:
    North Carolina
    Prop clearance is an issue with pusher flying wings.
     

Share This Page

arrow_white