This looks to be repeat of earlier post. My response to Bill was intended to demonstrate the dimensions of the bracket extension I used to overcome the difficulty described by Ralph.
Regards, Bill, John, The air pressure inside the cowl wants to open the nose gear door. You need a certain momentum to keep the doors closed. It is defined by the Force of the push rod (it remains the same unless we increase the diameter of the nose gear cylinder) x length of the arm The length of the arm can be changed by moving the attachment point of the push rod closer to the center of the airplane (this is what Brent Regan did if you read my earlier post). Unfortunately we can’t move the attachment point completely to the inside because the nose gear won’t fit in anymore. I hope I get to check it out on the weekend. I will make new brackets then. It will be a bent laser cut aluminum part that can be reproduced at almost no cost. If I find a sound solution I let you know and I can make the brackets for you. Ralf I do vaguely recall that the brackets are either too small or in the wrong part of the door (per the manual) to get the proper mechanical advantage. I am thinking Brent Regan came up with the discovery and the advice for fixing. It's been a long time, but I think I either made new brackets or put them in a different place or both. I could send photos and dimensions if you'd like. My doors seem to function well although no one has flown formation with me to observe how they close in flight. Yes, I think that we are talking about the same item Each nose gear door is actuated by linkage (rods) that attach to the door using a small "L" shaped aluminum bracket. It seem that if the bracket were a little larger, the pivot point (where the rod attaches) could be moved and thus apply a little more pressure to hold the doors closed in flight.. On Wed, Jun 19, 2013 at 12:29 AM, John Barrett <2thman1@gmail.com> wrote: Is the bracket you are referring to the horn that the push rod is attached to? I'm not quite sure what the bracket is. I bought two replacement aluminum doors from Lancair; primarily because aluminum hinges are still in the plane and they have always worked well. Dropping the doors was a simple matter of pulling the hinge pins. I am interested in enlarging the brackets that activate the doors because both of the connecting rods ended up having a slight curve after about 180 hours so there is considerable pressure on those rods. In addition, the right door bracket had a noticeable bend in it that I would like to resolve. If you have any specs on your brackets, I sure would like to see them On Tue, Jun 18, 2013 at 9:32 AM, John Barrett <2thman1@gmail.com> wrote: i made my nose gear doors out of graphite on my LIVP and used Carbinge to hinge them. Have about 70 hours on the plane now with no glitches. Very happy with the results. Can share design parameters if you are interested. I also made graphite angle bar to hang them, but that might be overkill with your engine already being mounted. I am making up a new set of nose gear doors (don't ask).. If you fabricate a new door bracket, please let me know the how and what. And how they work. (maybe Brent has a pattern??? On Tue, Jun 18, 2013 at 4:45 AM, Chris Zavatson <chris_zavatson@yahoo.com> wrote: The Outback gear doors on the 320/360 suffered a similar fate. The original actuation scheme couldn't handle the air loads. A small pressure differential over a large area generates a lot of force.
Dear subscribers,
I did the nose gear check as described Jack Morgan and Charlie Kohler
earlier. Everything went very smooth and the plane did not move at all
even when the weight on the tail and chucks were removed.
I cycled the gear 5 times and every time the nose gear door shut
perfect. This leads to the conclusion that my door shuts perfect after
take-off and reopens due to air-pressure like Brent Regan describes
below.
On the in-flight picture you can see how the door gets pushed open. This
was at a pretty low speed - approx. 140...150 kts indicated - I assume
it will get worse if I go faster.
I attached pics of my nose gear linkage versus Brent Regan's improved
nose gear linkage - if yours looks more like mine you probably have the
same problem.
Since there was so much concern about my jacks I attached a pic of the
gear check. My jacks work reliable and the plane sits sound on them.
They just don't have enough stroke. That's why I have little platforms
that I slide in and out. The set up works reliable - it is just a little
more work....
Ralf
-----Original Message-----
From: Brent Regan [mailto:brent@regandesigns.com]
Sent: Wednesday, June 12, 2013 11:37 AM
To: Lancair Mailing List
Subject: Re: Nose gear check 4P
Ralf writes:
"A friend took a picture of the belly of my airplane in flight with the
gear up. It looked to me that the nose gear door was not completely
closed."
The original factory nose gear door linkage geometry provided too low a
mechanical advantage to keep the doors closed against the internal
cowling air pressure during flight. On the door bracket, you need to
fabricate a new part with the link ball hole rotated about the hinge
centerline towards the AC center. This will give a larger effective
moment arm when the doors are closed. A slight kink in the linkage arms
is required. See pictures attached.
BTW, Selecting Gear Up while on the wheels is an incredibly bad idea.
Buy a decent pair of jacks NOW. Also, do NOT strap the spinner to lift
the nose. Remove the top cowl and strap the propshaft.
Regards
Bren Regan
--
For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html
<SKMBT_C36013062210570.pdf>
|