Mornin EZ
I'll throw a couple thoughts out.
1. I would guess it would be lighter.
2. Seems to be more trouble/maintanence free. Leaf springs seem to chafe on each other causing wear/breakage.
Just a couple of my quick thoughts, now lets hear from the experts
Gary

Hi Gary,
Leave the tuff stuff for the experts, the story I got on round stingers, is pretty basic.

Wayne, were ya been? Cessna calls your 'stinger' a tail cone, and my 'stinger' a spring... we are both fubar Your's is the accepted version for all aircraft though... If that bothers you, I bet you go nuts when people call tires wheels....

EZ,
Thank you for seeing through the 'not a spring' smoke.... It is a spring. That is why you don't see a lot of bent ones, even after some fairly punishing landings And yes it is even arched. I was told stingers were built round to allow omni directional flex without imposing as much twisting moment on the attach points.... If you have seen the attach points, they seem to support this theory... In fact anyone who has owned a s-cub (leaf springs) for any extended period of time will tell you that the first time you spin a 'stock' cub around and drop the tailwheel or tail ski into a rut, you will twist the tail, it's the reason for the multiple tail beef up's available for a cub. Had piper used a stinger, those x-braces and tail boxes may have never been needed...



Take care, Rob

I knew I would be stepping into muddy waters
Thanks Mr. Wizard

EZFlap wrote:Can any of you knowledgeable Cessna 180 historians explain what the reason was why Cessna went from the multiple leaf springs (C-120, 140, 170) to the round tube spring (c-180)?

Leaf springs were cheap and it would be simple enough to add more leaves or wider springs on their airplanes as the empty weight went up. I'm sure there was some reason they did it, but I'm not understanding what problem the small round tube solved that could not be solved with bigger leaf springs. One idea I heard is that they wanted a quickly removable tailwheel when an owner wanted to put the floats on.

Thanks in advance for the answer to this admittedly academic mystery.

The tube is MUCH lighter in weight, for a given amount of strength.

I also suspect that tube no more expensive to produce as well, assuming you have the fixtures set up.

The stinger (and that's what everyone I ever ran into called the "tube spring-thing') stays on the airplane when the plane goes to floats. Makes a handy place to push/pull, secure tiedowns and tail lines to, etc.

Mostly, it is MUCH lighter than a set of leaf springs would have to be to accommodate the weight on the tail of a 180/185..

MTV

Some pics I took last night.




And one to make them look big.

Looks good!

mtv wrote: The tube is MUCH lighter in weight, for a given amount of strength.
MTV

Thank you.

If there is anyone with additional knowledge on this I would very much appreciate learning whatever else I can on this subject.

I might have fibbed a little... it's not entirely academic

Terry you dog, looks great!!

EZFlap wrote:

mtv wrote: The tube is MUCH lighter in weight, for a given amount of strength.
MTV

Thank you.

If there is anyone with additional knowledge on this I would very much appreciate learning whatever else I can on this subject.

I might have fibbed a little... it's not entirely academic

Before you get the idea to incorporate a stinger into your 172 tailwheel conversion, go price them.

You're right Hotrod, they're horribly expensive... my inquiry was actually exploring going the opposite way when I add the 182 to the existing 172 tailwheel conversion. I'm trying to see what it is about the round stinger that makes it better or safer or cures the common cold faster than a regular stack of inexpensive flat leaf springs. MTV and others pointed out a weight difference in favor of the stinger. I can fix that easily enough. Any other advantages or necessities in favor of the stinger is what I want to hear about if I can.

Figured out the mystery that I had asked for help with. I know most of you were losing sleep on this, as was I

After committing a dastardly 'breaking and entering' burgulary on the Skywagons site, I found an excerpt from a book, written by one of the original gangstas who designed the 180. Their biggest reason apparently was drag reduction, so the sales and marketing guys could distance the Skywagon from the existing 170. However, I believe there were and are several other advantages to it which MTV and others had mentioned... side load shock absorption, and weight savings.

For that reason I'm looking into conjuring up a round spring design on both the 172 and 182 conversions. And Hotrod was right once again, cost is a primary concern. So taking the easy way out by supplying an OEN stinger ain't gonna do the job.

EZ

Seems like there are some light-sport aircraft (Rans S-7?) that use a rod style spring for their main gear. So that might be an aviation related source for a tail spring that is stout enough to hold up the aft end of a Cessna for your purposes. Better than starting from scratch and maybe lower cost because of current fabrication for other applications.

Thanks for the suggestion, I will in deed look into it, however it is difficult to FAA certify someone elses product without a certifiable quality control system. If they do have a good system (probably Van's etc. off the top of my head) then their pricing will reflect that, and the customer is paying for their profit and mine, driving up the price of the final product. It's a struggle to balance all that kind of stuff, on top of making sure the part is as good or better for the purpose as the OEM part.

EZFlap wrote:You're right Hotrod, they're horribly expensive...

As the gross weight increased Cessnas they switched to the tube gear. I believe they shot peen the inside of the tube to help with fatigue issues. I wonder if they use the same process on the 180, 185 t/w spring. It might be one reason for the price.

EZ, call Wup about the Cessna stinger. Rumor has it he has Been working on it.

Thanks, I might do that if I go with a stock design.

I am having shimmy problems with my new 180K. Before I start trying a bunch of things I thought I'd see if someone can give some advise. I understand the geometry thing and it doesn't look bad and the 1.125 inch tail spring doesn't look sagged out. I have been wheel landing and holding the tail up. I did put a new XP Mods 1 inch spring tailwheel with 10 inch tire on my old 1954 180 and that doesn't shimmy much----just once in a great while. Should I start with tightening the castle nut on the bottom or are those set screws that can be tightened or????? Thank you for any advice!!!!

There’s another recent thread that deals with this:

https://backcountrypilot.org/forum/tail ... lit=shimmy

Tail wheel spring geometry is addressed here:

I would take it apart, clean it, inspect it, grease it, and then try it again.
I'm not familiar with all those screws on top--
is this a McCauley tailwheel (as opposed to Scott)?

is this a McCauley tailwheel

I think so since it is original. I've worked on Scott before but not this type. Got a friend in Missouri with 185 and will see if he can help me out..