Lifting body + prone position ?

Discussion in 'Hangar Flying' started by Retroflyer_S, Sep 27, 2015.

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  1. Nov 2, 2015 #121

    D Hillberg

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    In a forced landing what would you want when you go full thumb tack????? broken ankles and toes or brain splatter and broken neck?
     
  2. Nov 2, 2015 #122

    Retroflyer_S

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    Depends how you force your landing.
     

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  3. Nov 2, 2015 #123

    D Hillberg

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    direction of flight has more of an impact wouldn't you think?

    (History of using helicopters to recover wrecks)
     
  4. Nov 2, 2015 #124

    BJC

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    I'm not following you. Please explain why that is apparent.

    Thanks,


    BJC
     
  5. Nov 3, 2015 #125

    Aesquire

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    That depends entirely on 1. if the cockpit is intact, and 2. how you are secured.

    There isn't a lot of GA or military work done on crash effects on a prone pilot. There is, however, a decades long body of practical experience in prone flying in Hang Gliders. If you crash prone, in a weight shift harness, you tend to swing forward, missing the ground, and hitting the wing. If you don't break your neck on structure, you tend to hit with your back & shoulders, going up into the wing. Restraint straps don't usually work for the flying part, and it's a gamble if the crash is survivable. The good news for Hang Gliders is during landing, you generally are not full prone, but in a standing position, so you don't usually have a full speed swing through. It does happen, remaining prone until the last second, when people try and stretch their glide into the landing field. ( why I always preferred a little altitude in the bank, to burn off in a high drag body position, modulated by speed )

    In an enclosed design, ( Not with head sticking out ) If the cockpit is intact, and you are not allowed to hit structure with a harness, you should be good up to a fairly high G level. At the extremes? I think I can safely say that when the g's are high enough to pop your head off your spine, the position you are in doesn't matter that much.

    I do rate prone as less survivable than supine, IF you don't load the spine directly, such as your Butt hitting solid structure or ground while still in motion. The science of building a high G survivable seat is just as critical no matter the position.

    Then again I could be wrong.
     
  6. Nov 3, 2015 #126

    RPM314

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    Slogan for the whole site.
     
  7. Nov 3, 2015 #127

    JamesG

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    Paging SVSUSteve (again)....
     
  8. Nov 3, 2015 #128

    Retroflyer_S

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    It glides mucho better than solar impulse with 40:1 ratio. That SI ( I+II ) has a very draggy non lifting fuselage.

    I figure even 9 m spanning would still have 30:1 glideratio at 17 kg/m2 wingloading...for 20 m span the loading is closer to 7 kg/m2.
     
  9. Nov 3, 2015 #129

    Retroflyer_S

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    With the wing loading these crafts fly there really isn't impact on landings at all. This was also found out in the 30ies.

    http://www.aircrash.org/burnelli/cella1.htm
     
  10. Nov 3, 2015 #130

    D Hillberg

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    mass is mass and stopping is stopping with a light wing loading or a heavy loading is not a factor at all. You clean up enough crashes from piper cubs -ultralights and fast movers you see 'wing loading' is a load .
    A forced landing is what it is and to design a machine with no regard to the fact that you will never screw the pooch "No impact" is full of Bull.
     
  11. Nov 3, 2015 #131

    Retroflyer_S

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    Well the impact you are craving no one survives ....even in the safest fuselage. That is no longer called a landing.
     
  12. Nov 3, 2015 #132

    BJC

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    My question is how do you know that it glides better than the Solar Impulse.


    BJC
     
  13. Nov 3, 2015 #133

    Retroflyer_S

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    It is based on the fact that this AC has less drag and wing loading...and similar aspect ratio in practise. It is almost educated guess, but since we know that SI 1 + 2 were designed to fly at nite time carrying half of total mass of batteries with extra heavy fuselage we can be certaing it is far from being an optimal ( motorized ) glider.

    I have also tested number of gliders as models....and tested mine as a model.

    I could make this a three seater ( all in prone position ) with 12 kg/m2 wingloading and having just less than 1/3 dimensions.....and fly at double the cruise power than SI I does on solar alone. In lay man terms that means 20 times more power/drag. With just 80 kg of batteries it could climb above the clouds even on a rainy day.

    It is not only because of the lifting fuselage, but also the material used and the lay out efficiency of the design.

    If you check out the McCready lagacy you'll found out that there are several details that are better in Solar Challenger than in SI I + II.

    SI I cruise power loading is 0.004375 kW/kg.....and this " Barsoom Scooter " has just below ten times more ( 0,0364 kW/kg )...at a fraction of the drag.
     
    Last edited: Nov 3, 2015
  14. Nov 3, 2015 #134

    D Hillberg

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    I don't crave anything just pointing out If you use only one criteria for a design you are going to kill your passengers for no good reason. leave out the prone position'

    (try it for long periods you wont like it - Air force tried and gave up on it that might be your first clue)
     
  15. Nov 3, 2015 #135

    Retroflyer_S

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    I agree that prone position in any other AC than this would be less than desirable.

    This song derscribes the craft the best; https://www.youtube.com/watch?v=VtcxApSZLvU
     
    Last edited: Nov 3, 2015
  16. Sep 8, 2019 #136
  17. Sep 8, 2019 #137

    bmcj

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    OK, someone dredged up another necro-post (maybe it was new since the banning).

    Anyway, it gives me the opportunity to offer another thought on the prone vs seated debate.... for those that advocate prone, do you sleep or rest by laying face down on your stomach? Do you converse with your house guests while laying on your stomach? If not, then why would you ever consider prone flying more functional or comfortable. Yes, it may offer a little more streamlining (which is only marginally important at hang glider speeds), but supine also offers reduced drag.

    Let’s put it this way... if I were Superman, I wouldn’t be flying around like he did in the old television show, I’d fly around in an upright or seated position. Much easier to look around that way.
     
  18. Sep 9, 2019 #138

    BJC

    BJC

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    Sure, but would Lois .... never mind.


    BJC
     
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  19. Sep 9, 2019 #139

    mcrae0104

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    Thankfully, Superman was more concerned with truth, justice, and the American way than he was with ease of looking around.
     
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  20. Sep 9, 2019 #140

    Speedboat100

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    I think reclined seating position like in the F-16 and gliders ( sail planes ) is the most desirable.
     
    Last edited: Sep 9, 2019

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