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New RV-7A nose gear

Pbr47906 said:
Mick:

Aerostars use a left-right rocker switch below the throttles for nose wheel steering. Any thoughts to that type of steering. I was first against it, but when you treat it like a tiller wheel, I really liked it. Steering is mainly for taxi and line up and as soon as power came up, rudder authority was sufficient. The toggle could be placed on the control column. Your thoughts?
Click to expand...
Does it castor freely if you aren't pushing on one of the switches, or is it frozen in whatever position you last put it at?

If it castors freely when not being driven, I'm not sure I see the advantage over one that castors all the time. The extra weight, complication and failure modes don't buy much.

If it is frozen in the last position when you aren't pushing on the switch, I fear it could be a handful during landing if it wasn't perfectly centred for some reason. E.g. maybe someone inadvertently hit one of the switches in flight.

I vote for a free castoring nose wheel. Simple, cheap, light and reliable.
 
first test

Just another update. Weather clear and hot and the field is bone dry.
Started the engine for the first time in about 12 months and found it will need some adjustments to the idle as I was unable to get it below 1200rpm. During the installation of the steering linkages, I removed the mixture and throttle cables but must have reinstalled them slightly out.
With the help of Jon Clements and my son Daniel we began with just a slow straight run and then moved onto turns using just brakes and then just full rudder with maybe a small amount of brake. No easy task when I was just sitting on a couple of cushions. I looked vertically challenged and found it a struggle to see over the panel. We found that the nose gear does indeed caster and self center, although this was all done at slow speed it felt easy to control and really no different to the standard nose gear. The turning limit stops have yet to be fitted and we found it really only requires around 10 - 15 degrees each way for a reasonable turning circle. I will fit stops so we can adjust the maximum turn but at this time just wanted to see how much turn would be required. When the nose wheel was at approx 45 degrees and the plane not moving I found by applying power and no brakes it would center the nose wheel and was then able to initiate a turn with little effort.
The actual nose fork will need to be strengthened as there is a small amount of side movement still evident when at full side caster. The suspension appeared to work as I had hoped with the dual springs doing there job of smoothing things out.
I have not fitted the shimmy dampener as yet as I would like to test the natural stability of the nose gear before fitting it and moving onto faster speeds.
Once my son downloads some footage of the initial test I will post it here.

Stay tuned.

Cheers
Mick
 
Good Job Mick

Hi Mick,

Can't wait to see. Well done so far and good work. I am very keen to see the out come.

Cheers
Jay
 
video, first test

The initial test has shown that the suspension is working nicely, I have yet to set the steering limits and at one point near the end of the video you can see the nose wheel turn almost 90 degree's as I was testing the turning circle. The good thing is that the wheel straightened with application of power, proving the Castor is working. No steering dampener was fitted for the test as I need to know how stable the nose gear is without it, I will fit the dampener once the steering limits have been set. All mounting points for the gear were marked with tamper proof paste and have shown no movement after numerous test runs.

http://www.youtube.com/watch?v=wWbEmOqrb4A

Cheers
Mick
 
It looks very stable,,,it moves much less than the mains on grass, you are definitely on to something there. Keep up the good work.
 
second test

I have uploaded another video filmed directly behind the gear. It shows the nose wheel tracking the undulations but when at higher speed it smooths out. At the moment there is no friction in the steering and would expect the standard Vans nose gear to do the same without the 30Lbs of brake out force.
I will refit the standard gear and film from the same angles just to confirm.

http://www.youtube.com/watch?v=lKjyARhgXdU

Cheers
Mick
 
Just added another video.
I found the cause of the rich mixture.. I had a loose line at the fuel pump!!! Not the cable adjustment as I first thought.

iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/1oqDzceXOOM?rel=0" frameborder="0" allowfullscreen></iframe>
 
Last edited:
FANTASTIC!

Fantastic! This may just be the solution that will make me build an A-model eventually. So, I think I missed a tidbit - did you solve the nosewheel steering, or are the videos shot with caster-only?
 
scsmith said:
Fantastic! This may just be the solution that will make me build an A-model eventually. So, I think I missed a tidbit - did you solve the nosewheel steering, or are the videos shot with caster-only?
Click to expand...

I have only tested with a castering setup. I don't think the steering linkage system was very practical. Now that the engine has been sorted I will move onto faster speeds once I refit the flight controls to the wings. I really need to now the limits of the caster without the shimmy damper. One step at a time!.
Mick
 
Mick
My hat is off to you. That gear without a dampener is better behaved than the gear on my Cardinal is with one.
 
ColoCardinal said:
Mick
My hat is off to you. That gear without a dampener is better behaved than the gear on my Cardinal is with one.
Click to expand...
Carl
Thanks for your comments. It would be interesting to see what the Cardinal gear is doing on different surfaces and at various speeds.

I did a weigh on my nose gear and found it has 273Lbs (fixed pitch metal prop, IO360) it would be interesting to see how it performs on a 7A with a constant speed prop. It would be helpful to hear from others with their nose gear weights. To benefit those with a constant speed prop and I'm happy with the high speed tests I will look at raising the weight on the nose wheel to replicate a 7A with a higher nose wheel weight.

Mick
 
Mick,
I can tell you that, on the Cardinal at least, the nose wheel tire pressure is critical. It is most likely to shimmy if you fill up the tire with a few PSI over recommended pressure; taxi a little fast on a cold morning when the tires are flat-spotted from sitting over night; travel on a hard surface and hit a little bump. Viola, you'll be forced to come to a complete stop before you can get it to stop trying to shake the plane apart. If you can eliminate ALL slop in the system you can prevent it. I'm talking about a couple thousands of an inch here.
Best of luck on the testing.
 
Snowflake said:
Mick,

Never mind the nosewheel... I want more info on the tip-up canopy! :)
http://www.youtube.com/watch?v=1L80cmVyKTQ
Click to expand...

Started as a joke with a fellow RV builder over a few beers after a long day building, maybe a bit to much sun as well !!. The system uses two pneumatic rams, compressor, solenoid and a two channel remote control. A micro switch is fitted to the canopy latch so it will not activate when the canopy is locked. The canopy can be opened and closed by hand if the compressor is not running but needs a stay if there is no air pressure in the rams. The total cost for system was around $250 a couple of years ago. You may have noticed the canopy also has extensions to the lower edge which covers the standard gap between the canopy and fuselage. Anyway it's something different and it does work well.
Mick
 
Hey Mick:

How is the steerable nosewheel coming along? It's been a while since we've heard from you. Just wondering how it's going.
 
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