Rocket Steering Link Geometry

[scsmith]

Originally Posted by RV7Guy

In conjunction with Steve Smith JD Air has developed a new arm with improved geometry. Steve is flight testing now and any tweaks will be made based on the flight testing.

I hope we will have this done and ready to go in early November. Thanks for your support!!

Since I last posted on this thread and others about the asymmetrical geometry of the "rocket" link, Darwin at JD Air Parts connected with me and we have been testing a new steering arm. I worked out an alternative geometry for the steering arm that makes the tail wheel deflection symmetrical and has the correct travel so that it releases the lock to allow the tail wheel to swivel at the right point. This was done by finding the right combination of sweep angle and length of the steering arm. Darwin graciously made the new arm and I have been flying with it now for several months. Here is a picture:



Installation of the swept steering arm also requires a longer link. In my case, the center-to-center length is 14". Darwin was able to supply the longer link along with the arm.

It does indeed have very nearly the same deflection to the right and left, and the release point is right where I wanted it. If you go to full rudder travel, but have pressure on the tail wheel trying to make it straighten, as you would any time you are landing or taxiing, the swivel will not release. If you go to full rudder travel and then apply additional pressure in the direction of the deflection, as you would if you were moving the airplane on the ground and wanted the wheel to swivel, it does release. The additional travel allowed by the springs in the rocket link accomplish this. The result is a link that feels pretty much exactly like the original rocket link, with the added benefit that it will not release the wheel to swivel unexpectedly.

The one caveat that I would alert people to is that not everyone has their rudder stops in exactly the same location, so there is some variation of maximum rudder travel among all the thousands of RVs. While in my case the release is exactly what I think it should be, meaning full rudder travel plus some additional travel from the link springs is enough to release the swivel, others may find that rudder deflection alone might release the wheel, or might find that the combination of rudder deflection plus link spring deflection is not enough to make the wheel release. This variation in rudder travel is not something the vendor can control. You can be assured though that your tail wheel deflection will be nearly symmetrical right to left.

[DougCronkhite]

Is it available to the public yet?

[RhinoDrvr]

All this engineering and pain for what net improvement to chains and springs? I'm very happy with my chain setup. What is the benefit of the rocket link, against the added trouble to get the setup satisfactory for safe operation?

Not trying to be a naysayer, just don't see the draw to the link despite all the crashed airplanes they've caused (or assisted in causing)...

[Mitch757]

I had a similar tailwheel unlock situation when I landed my newly acquired RV8 with a slight right crosswind. After touchdown, I got a fairly large gust which the rudder could not completely correct. I lowered the tail thinking I now had steering and found that I was pretty much a passenger since the tailwheel was unlocked.

I made a "controlled" departure between a couple runway lights at a turnoff.

No damage occurred and I was lucky...this time.

After evaluating my setup (Tail Lynx system), It appears that the engagement groove in the tailwheel itself is not routed far enough both directions to prevent unlock at full rudder deflection.

My neighbor is a machinist and he is going to mill out the engagement groove so that I have full rudder deflection with the tailwheel still engaged.

My two previous planes, RV4 and PL4, both had Aviation Products Inc systems and they worked perfectly, only disengaging with brake application.

Mitch Garner
N188R

[RV8JD]

Originally Posted by scsmith

<SNIP> I'm a little surprised that my picture and post hasn't generated more dialog, given the level of interest to my earlier posts highlighting the asymmetry and the unexpected release in a big cross wind.<SNIP>

I like the better geometry. I'm waiting for the version with an integrated tie down ring, like the Flyboy Accessories' control arm has. It is very handy.

[scsmith]

Originally Posted by RV8JD

I like the better geometry. I'm waiting for the version with an integrated tie down ring, like the Flyboy Accessories' control arm has. It is very handy.

You will have to ping Darwin so he knows that is a feature that his customers would want.

[scsmith]

Originally Posted by RhinoDrvr

All this engineering and pain for what net improvement to chains and springs? I'm very happy with my chain setup. What is the benefit of the rocket link, against the added trouble to get the setup satisfactory for safe operation?

Not trying to be a naysayer, just don't see the draw to the link despite all the crashed airplanes they've caused (or assisted in causing)...

It is probably a stretch to accuse them of "crashed airplanes they've caused". A few partial ground-loops that fortunately seem to miss the lights and signs.

Seriously - It definitely is a preference thing. The rocket link is crisper in response, without the lag. If you set chains so there is no lag on the ground, they put a sizeable load into the bottom rudder hinge when the tail wheel spring relaxes in flight. It is also tidier, given that it is only on one side.

But it definitely is a personal preference thing.

[Ironflight]

Originally Posted by RhinoDrvr

All this engineering and pain for what net improvement to chains and springs? I'm very happy with my chain setup. What is the benefit of the rocket link, against the added trouble to get the setup satisfactory for safe operation?

Not trying to be a naysayer, just don't see the draw to the link despite all the crashed airplanes they've caused (or assisted in causing)...

I agree with Steve?s comments (above) - we use Silver Bullet links (no longer available, but the same concept) on all of our RV?s - thousands of hours, no issues, no problems, crisp handling, very clean installation, no ?crashed airplanes?.... It?s personal preference if you like their handling.

Paul

[RV7Guy]

I have the new geometry arms being fabricated now and will have steering links completed soon. I'll make an announcement here when they are ready to ship.

I have not flown this combination but Steve has put forth a great effort in making this happen. There is certainly nothing wrong with the current system but we are always looking for improvement.

Regarding the tie down ring on the arm, I'm not convinced this is a good place to tie down the plane. Any movement of the tail is going to cause the arm and locking pin to interact potentially causing nicks and burrs in the metal. The tail parts take a beating as is and there is no reason to add to that. However, if people like them, I'll see about having them made with a loop.

The one problem I see over and over again is a lack of MAINTENANCE on the tail wheel assembly. I'm going to start a separate thread on the proper care and maintenance of the tail wheel assembly.

[Snowflake]

Originally Posted by RhinoDrvr

Not trying to be a naysayer, just don't see the draw to the link despite all the crashed airplanes they've caused (or assisted in causing)...

Given the RV's fly and handle wonderfully on the ground with neither chains nor steering link, i'd have to say that any accident that happened with either installed was probably more related to complacency than the hardware.