REFLECTOR: Video of NOSE GEAR DOOR DO-HICKEY

Dave Black dvblack at comcast.net
Mon Jun 6 21:40:09 CDT 2005


Tom,

> Thanks for the thorough explanation. You can tell I had not thought it
> through.

I would not say that at all. As you know, I have long been a proponent of
fixing the original design through relocation of the sequence valve. I really
must hand it to you for thinking outside the box on this one. Once fine-tuned,
your mechanical method will be simpler to install and maintain than the
hydraulic method. And I KNOW your door will close when it's supposed to and
never slam. 
 
> Tonight I worked on concept to hold the doors closed when there is nose
> wheel bounce from turbulence. What I came up with is to replace the UHMW
> roller with a compression spring. When fully retracted the spring is
> completely compressed, holding the doors tight. If the nose wheel bounces,
> the spring would relax slightly, but still have a force holding the doors
> closed.
> 
> What do you and others think? On the right track or throw it out and try
> again or ??????

I think you are on the right track. Certainly this will take out any little
'wobbles' in the doors due to slight movement in the gear during flight. On
the flip-side, that spring will have the effect of trying to force the gear
itself down somewhat. I have no doubt the hydraulic system can hold it,
though. It holds the much heavier main gear up. 

The other small detail I see is opening the doors. The current design would
require the nose tire to push the doors open as it fell, while the hydraulic
system actually powers the doors open. This is not necessarily a problem, but
it is a factor to be taken into consideration when refining the system. I
suppose one option would be to have a second UHMW roller on the underside of
the gear leg, so it could push the doors down. On the other hand, in the
interest of keeping it simple there's nothing really wrong with the tire
pushing the door open. 

I keep thinking that this mechanical system will benefit from over center
springs on the doors themselves. That way, the doors will either be open or
closed -- not somewhere in between. And not flapping in the breeze. Obviously,
an important part of the fine-tuning of this system will be choosing the right
springs. 

> For the proof-of-concept I used a hose clamp to fasten a spring to the NG
> strut. As mentioned above, I think the final design should have the spring
> mounted to the short link arms in place of the UHMW roller. Another
> improvement is a shorter stiffer spring than the one I have. 

It certainly sounds to me as though you are on the right track!

> I also have a video of it in action. 

Can you e-mail that to me?

Dave Black
Shortwing RG


More information about the Reflector mailing list