Tail Wheel Spring

[geraldmorrissey]

Can anyone comment on round vs flat tail wheel springs. I've flown a RV with a round spring a few times but I couldn't really feel the difference. With that exception, all my tail wheel time is in aircraft with the flat spring. What do I need to know before considering one or the other. The round spring looks lighter.
Thanks
Gerry
Patrol #30

[Enewton57]

I have heard that tail wheels using the round spring have less of a tendency to shimmy than do the flat leaf spring. I have no proof one way or the other, that's just what "they" say. The leaf spring does kind of settle a bit after several hard landings (not than any of use ever experience hard landings) and has to be re-arched to keep the tail wheel kingpin angle correct. I haven';t seen that as much with the round spring but I guess it is possible.

[sjt]

[Battson]

Are you talking about a stinger, like on a Cessna 180?

They are good and bad. They can flex more easily in all three dimensions, but they also seem to crack more easily. Just observations.

[mswain]

Both of the Bearhawk builders I know here in Jacksonville use a stinger arrangement, this is after using the plans leaf spring arrangement first.

The first version that was built with 19-2 stainless ultimately cracked and failed where the wrist pin hole was. The second stinger was made from 4340 then heat treated to a Rockwell 43 to 45.....I think it ultimately came out at 44. Supposedly this alloy and heat treatment is the same used in other aircraft gear arrangements.

[dedgemon]

The round rod seems to work fine on the RV's (similar weight to the Patrol). The only caveat is that it will tend to wear the hole in the socket and allow the rod to move a bit in rotation. This can generally be secured a variety of ways. I just fixed mine (RV8) with a loctite product designed for securing gears to shafts. Can't remember the number off top of my head. 648? maybe?

[Battson]

A friend who also happens to be an experienced instructor and highly experienced IA / AP has been using a Cessna 180 stinger on his PA20 for a long time now (for serious off airport work, with Baby Bushwheel). His just cracked at the tailwheel fitting. He told me he is going back to the leaf spring, for a combination of reasons.

ps. Not saying leaf springs are better, just providing another data point.

[swpilot3]

Do you happen to know what those reasons were?

[Battson]

Basically the following were better with the leaf spring in his opinion IIRC:

- Durability in severe off-airport conditions, and I mean servere
- Field repair-ability
- Compliance with Type Certificate
- Other reasons I can't recall

[swpilot3]

Cool. Thanks Battson!