Posted by Jorgen on Saturday, March 28, 2009 @ 03:22 AM:
Hi Guys,
I noticed that Collinīs RF 4 had a notch in the cut out for the lower rudder horn linked to the tailwheel (se pic on the Miscellaneous-getting your RF in the hangar-thread). I checked XST yesterday and found an even deeper notch in the groove for the lower rudder horn (left side) and Bob has a similar damage on his blue one (see "Modifications- reduce your landing gear drag"-thread). Probably the spring tension hasnīt got all that much to do with it since itīs unlikely that we all three have springs that are too loose, but maybe the "bootful of rudder" that we might have used doing left stallturns might explain it. And of course since Bob said itīs difficult to make them to the left we just had to try, didnīt we?
Itīs probably no big deal as long as you keep an eye on it. The "stop" for the rudder is located at the main rudder horn, so the notching at the lower rudder horn versus the groove in itself must be secondary to what travel you have at the stop. Note the compression-type springs (AirCraft Spruce has them) for the tailwheel steering that I think improves crosswind capability. Pardon the dirt on the plane, itīs been washed since...
Take 5(b) just 4 fun/ Jörgen
Posted by Sam M. on Thursday, April 2, 2009 @ 06:37 PM:
Mines the same way
Posted by Bob Grimstead on Thursday, April 2, 2009 @ 09:04 PM:
Yeah, the old Wagon's even worse!
I think it's just one of those things that happens to Fourniers with time (and tailslides).
Yours, Bob
Posted by jb92563 on Friday, September 30, 2011 @ 10:15 AM:
Mine are tight so the tail wheel follows the rudder more directly.
I had a slight bit of slack before and tightening and stronger springs helped the taxi on my dirt field. On pavement it is no problem either way.
I did manage to damage a spring early on before I realized that you can not push the RF4D backwards on dirt since the tail wheel
will just turn 90 degrees due to the springs when it comes up against enough resistance to rolling.
Now that I think about it a compression spring would be a much better solution since it has a built in max compression stop after which
it will just act like a solid connection.
[Edit by jb92563 on Friday, September 30, 2011 @ 10:17 AM]
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Posted by dannparks on Friday, September 30, 2011 @ 12:44 PM:
This brings up a question of rudder control stops. The rudder pedals have forward limit stops that prevent the rudder horns from gouging into the plywood from pedal operation -- IF you adjust the cables to prevent this. However the tail wheel (during ground handling or taxi turns) can over-ride this and force the horns into the plywood. Does it make sense to make a true control stop on the upper horn?
This will also limit the tail wheel rotation, beyond full rudder deflection, to what the springs can absorb. In this case compression springs will force a limit, but extension springs could allow more tail wheel rotation on the ground.
Id certainly like to prevent my newly refinished wood from getting all bashed up if it did not have adverse effects on handling.
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Posted by jb92563 on Friday, September 30, 2011 @ 03:43 PM:
Although a proper control stop is probably the right way to prevent the problem, I think
it is so minor an issue that perhaps some thin aluminum in the potential wear areas might
solve the problem just as well and is a lot simpler to install and maintain.
I think it ultimately comes down to how elaborate do you want to go.
In weighing the options you would have to dig into your new paint to install stops, so perhaps rasping
out some additional clearance might be just as much work, but using a good 3M transfer tape(Or small screws) to stick down
a couple 1/2" squares of thin T2024 aluminum will save your finish and take a fraction of the time/cost to install and be a better
control stop than the wood.
If you need some good 3M transfer tape I'll send you some gratis. I had some that was used to hold down Tedlar (like Mylar but stronger) wing skins onto an aluminum wing (Lazair).
I personally opt for the lightest simple solution as all these little things do tend to add complexity
and weight.
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Posted by dannparks on Sunday, October 9, 2011 @ 06:07 PM:
I went with Ray's simple idea of just attaching some thin shields to the vertical stabilizer.
Simple, light and does the job. Probably could have used some smaller screws though. Rudder peddles are set so full peddle travel just touches the shields.
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Posted by Bob Grimstead on Monday, October 10, 2011 @ 10:25 AM:
Hi Dann,
That's great.
Just ensure you have measured and checked that you have the full angular rudder travel in both directions, or you will have difficulty getting out of a spin.
Yours, Bob
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Posted by dannparks on Monday, October 10, 2011 @ 11:03 AM:
Thanks for reminding me about checking for published control surface deflection angles. I found them in the Flight Manual.
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