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Thread: flying with doors open Max speed?

  1. #11
    Senior Member akarmy's Avatar
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    Default Re: flying with doors open Max speed?

    In my series 7 I like it around 80mph, above that it gets windy and noisy and I worry about the doors out there. I've been up to 110mph and it was fine but I mostly use it for a nice warm evening just flying around the local area and 70-80 is fine for that!

    Agree with others, don't slip with both open or there will be a lot of wind coming through. Also I had my jacket fly from the back of the baggage area, over my head and out the door while on the takeoff role faster that I knew what was happening. Found it sitting on the numbers at the end of the runway on the next t&g!
    Andy Karmy
    Kitfox 7 - 912S - SOLD
    Auburn, WA

    http://kitfoxflying.com

  2. #12

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    Default Re: flying with doors open Max speed?

    I have a model 2 and took the doors off. It flies fine 80-85. I did notice a little drag on take off. But doors off is the way to go!

  3. #13
    DesertFox6's Avatar
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    Default Re: flying with doors open Max speed?

    Schoenen Gruss, Olaf -

    I suspect your doors close because the gas door spring struts are old and worn out; after a number of years they just lose their holding power. I'm on my second pair of door spring struts on my Model IV; the first ones lasted about 12-13 years. Use the 35 lb.(approximately 47 newton meter) ones for Models I through IV; Part Number 16001.000 in the Kitfox catalog.

    The air pressure gradient beneath your wing and above your doors is a highly variable condition but in no case will it keep your doors open in flight. At very high angles of attack you may be able to force the doors to stay up against the wing but then you'll probably be busy recovering from the stall!

    "E.T."

  4. #14
    Senior Member
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    Default Re: flying with doors open Max speed?

    I know there is some difference between the Avid and Kitfoxes, especially from the Kitfox 4 and later. That being said, I've had no problem flying with the door open on my different Avids, and only the last one had the shock absorber to hold the door open. I've found that there is a fair amount of pressure holding the door against the wing at normal cruise speeds. You can feel the pressure when you start to close the door. Jim Chuk

  5. #15

    Default Re: flying with doors open Max speed?

    I suspect your doors close because the gas door spring struts are old and worn out; after a number of years they just lose their holding power. I'm on my second pair of door spring struts on my Model IV; the first ones lasted about 12-13 years. Use the 35 lb.(approximately 47 newton meter) ones for Models I through IV; Part Number 16001.000 in the Kitfox catalog.
    Hello and thanks for answer but my gas door springs are new, I bought it last year. They have 110 NM and works well on ground, but there is no chance to hold the door open during flight.
    During a slow flight by 60-70mph I have to push the door open and you could feel the pressure. If I let the door go it close itself slowly!? Notice, I use a 582 and I have a propwash from left-turn propeller.

    May be I have to fly faster? :-)

    Olaf
    Last edited by Olle1975; 07-07-2014 at 10:29 PM.

  6. #16
    DesertFox6's Avatar
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    Default Re: flying with doors open Max speed?

    Well, I guess I've run out of ideas Olaf; I've never heard of this particular situation with new gas door springs, but I guess I won't be able to say that again!

    I flew my Model IV its first full year with a Rotax 583 (a snow-mobile engine quite popular around here until the availability of the 912) which had a "left-turning" prop but never had any such door-closing problems, so your 582 shouldn't be the problem.

    I'm beginning to think your doors may have more camber at the forward edge for some reason that's causing a downward pressure gradient pushing them closed. For sure, SOMETHING is overpowering those gas/spring struts and at 110NM, it's got to be something quite significant.

    Okay, TeamKitfox; this is where we shine by sharing: Who's got the clue?

    "E.T."
    Puzzled in Peoria, Arizona

  7. #17

    Default Re: flying with doors open Max speed?

    Thanks for your comprehensive reply E.T.

    Something I have to add, my gas struts are not mounted in the front of the door like the most kitfox, they are mounted at the rear side, backwards. I think, thats a possibilty to have more camber at the forward edge for getting more pressure during flight!?

    My gas struts aren't very strong, it's very easy to pull/push the door open/close on ground.

    Next opportunity I try to mount the strut at the front of the door.

    Olaf

  8. #18
    DesertFox6's Avatar
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    Default Re: flying with doors open Max speed?

    AHH-HHAAAA! -

    By George, I think you've solved your own mystery, Olaf!

    This is why it's so hard to diagnose something from the opposite side of the planet without photographs of the offending parts under discussion: We mystics can't see through all the smog on our east coast when gazing at Kitfox problems in Europe!

    Moving your gas struts to the forward edge of your doors, as originally intended, will no doubt correct your door-closing problems in flight. Don't worry about the struts being up to the job; if they're even half as strong as new, they'll do the job. Those 110 NMs are more than enough to provide many hours of open-door summer flying fun; just move them forward and enjoy the breeze!

    "E.T."
    (Our "breeze" with the doors open in Arizona right now is 50 degrees C! )

  9. #19

    Default Re: flying with doors open Max speed?

    Hi!

    I think, I didn't solved my own mystery ;-)
    My door-struts in the front don't let the door open during flight.
    Look at my doors, they have a little camber in the front. I think, this is the reason for my "problem".

    Olaf


  10. #20
    mtgsxr's Avatar
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    Default Re: flying with doors open Max speed?

    I like to fly with the doors off. it only takes a few minutes. Less drag and no stress on the door frame. off in the summer on in the fall for me. put along at 90-100 all day long.. no issues.
    KF IV 912 N212LH

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