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  #21  
Old 01-24-2013, 04:50 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,573
Default Lower drag, better integration

Your yoke design has significantly less aerodynamic drag than the Bell and Aviation Products yokes. Also, it would not be difficult to design a nice tail wheel pant that fits onto it. Perhaps you could provide the yoke with a couple of #8-32 tapped holes in it that would facilitate mounting of a fairing?

I do like the added tail height of the Bell style, helps see over the nose, but that is by no means a deciding criterion.

Nicely done!

An additional thought on the links, in response to some folks' desire for a bit of "play". If you could maintain the basic design, but increase the amount of travel in the springs by making the outer tube longer, and using somewhat softer springs, then you might get the best of all worlds. No actual play, instant response, but somewhat softer, more gradual 'transition' that would help in cross winds.
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Last edited by scsmith : 01-24-2013 at 04:53 PM.
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  #22  
Old 01-24-2013, 05:15 PM
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rocketbob rocketbob is offline
 
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Location: 8I3
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Quote:
Originally Posted by scsmith View Post
No actual play, instant response, but somewhat softer, more gradual 'transition' that would help in cross winds.
I've made a couple tailwheel links for guys and my design is a little bit simpler and more robust than some of the commercially available ones. Its hard to find variable springs to do what you are talking about but its entirely possible to use a couple of different stacked short springs of varying spring rate to do this. I've also thought about using elastomers but the spring rate changes with temperature.
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N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
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  #23  
Old 01-24-2013, 05:21 PM
Jason Krause Jason Krause is offline
 
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Location: Glendale, AZ
Posts: 65
Default

Hey guys,

Guess I should not have opened that can of worms. I would really prefer to keep this thread on track with the yoke, not about steering spring design.

Thanks for understanding.
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RV-7 SB Finish Kit
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RV accessories including TailWheel Steering Links,
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  #24  
Old 02-02-2013, 04:34 PM
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rocketbob rocketbob is offline
 
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Default

Today I modified the tailwheel assembly to use a sealed angular contact mountain bike headset bearing. Machined some spacers and cut 0.400" off the bottom of the weldment with my mill. The cup is not pressed on or part of the weldment, the three pieces just drop onto the shaft and are sandwiched between the weldment and the fork. Just pushing the airplane around the hangar it makes a huge difference and the side effect could be that the airplane could easily weathervane if its not chocked or have the parking brake on. I like it.

Bearing, available on Amazon:
http://www.amazon.com/AheadSet-Ahead...ords=HSS20133K



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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #25  
Old 02-03-2013, 06:31 AM
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The Wizzard The Wizzard is offline
 
Join Date: Nov 2009
Location: Cincinnati, Ohio
Posts: 149
Default Steering linkage

I would love to see somebody come up with a steering linkage that is less sensitive than the JD airparts! There has to be an affordable way to do it. The JD airparts is to sensitive for crosswind landings but looks great.

One other thing, does a tailwheel pant really make a difference in speed?

I know this is not the original intent for this forum but since we are on the "tailwheel subject" why not!

Dave
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  #26  
Old 02-03-2013, 06:42 AM
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rocketbob rocketbob is offline
 
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Quote:
Originally Posted by The Wizzard View Post
I would love to see somebody come up with a steering linkage that is less sensitive than the JD airparts! There has to be an affordable way to do it. The JD airparts is to sensitive for crosswind landings but looks great.

One other thing, does a tailwheel pant really make a difference in speed?

I know this is not the original intent for this forum but since we are on the "tailwheel subject" why not!

Dave
Dave, you could take it apart and put softer springs in it. In my picture you can see part of the link I made and its a bit larger, the size dictated by my choice of springs which are a bit softer (what I had laying around.) The springs really don't have to be heavy at all, as long as they don't "bump" if they bottom out.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #27  
Old 02-03-2013, 07:25 AM
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DanH DanH is offline
 
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Location: 08A
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Quote:
Originally Posted by The Wizzard View Post
I would love to see somebody come up with a steering linkage that is less sensitive than the JD airparts! There has to be an affordable way to do it. The JD airparts is to sensitive for crosswind landings but looks great.
The sensitivity thing isn't a matter of spring rate. It is lever ratio.

In a stock setup we usually connect the chains, cables, or single link to the rudder arm at the outermost end of the arm, just so the chains/cables/link does not rub against the fiberglass bottom fairing when the rudder is fully deflected. The result is roughly a 1-to-1 ratio (rudder deflection angle is matched by tailwheel angle), since the rudder arm and the tailwheel arm are about the same length.

You make a tailwheel less twitchy by reducing the ratio, i.e. less tailwheel deflection than rudder deflection for any given displacement of the pedal. You do it by reducing the length of the arm at the rudder connection (move the connection point inboard) or extending the length of the tailwheel arm.

If you are using dual chains or cables, drill a hole in the rudder arm inboard of the usual hole and install a AN42B-10A upside down with a stack of washers to space the eye a low as possible. Connecting to the eye will probably allow your chain/cable to clear the rudder fairing.

Many of the lovely links out there come with a single sided replacement arm for the tailwheel. Reducing the ratio is merely a matter of making that arm longer.
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  #28  
Old 02-03-2013, 08:10 AM
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rocketbob rocketbob is offline
 
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Not a good idea Dan, have fixed a couple of broken links for myself and others where the the 1/4" tubes failed. I fixed them by changing over to stainless rod. Changing the ratio would increase the stress on these parts.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #29  
Old 02-03-2013, 08:23 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by rocketbob View Post
Changing the ratio would increase the stress on these parts.
Nope........
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  #30  
Old 02-03-2013, 08:30 AM
Lars Lars is offline
 
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Location: Davis, CA
Posts: 1,156
Default bearing grease

Almost didn't dare write that title, for fear of starting yet another "grease war"...

But. I have several bikes (another weakness of mine) with that type of bearing. In my experience, the grease installed by the manufacturers isn't the greatest. Even on my road bikes the stuff seems to find its way out quickly despite the seal, particularly the bottom bearing. I've taken to popping the seal out with a dental pick before first use, and forcing in (fingers work great) what ever red synthetic grease I have lying around. The bearings last noticeably longer for a couple minutes work.
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