Light weight Leaf spring?

cgarr · cgarr's Garage

Broke my tail spring on the plane, not because it was not heavy enough but because I had heated it and bent the end and didn't treat it right.

Anyhow this thing weighs 4 lbs and want something lighter on the tail, I have seen jeeps use fiber glass leaf springs, so what else is out there? Alum, carbon fiber, titanium etc?

It's an 1 1/2 wide and 18" long

cashflyer · 10-05-2014, 02:55 PM

I'm sure your plane is non-certified, so I will suggest that you stop by biplaneforum.com and ask those guys. Lots of tailwheel knowledge over there.

Also, the RV forum may be of help.

I guess if your plane is light, maybe you could use a single leaf instead of a stack?
U30512-002 PIPER TAILWHEEL LEAF SPRING - MIDDLE - Univair Aircraft Corporation

For lightweight wheel assy, you could check out this one:
http://www.wingsforum.com/viewtopic.php?f=218&t=23464

cstreit · cstreit's Garage

Carbon fiber...

http://lmgtfy.com/?q=carbon+fiber+tailwheel+spring

island911 · 10-06-2014, 07:14 AM

Yeah, those CF tail-wheel springs look great. ...for an RC toy. :-/

Seriously, CF has some low strain to failure ... the fibers aren't stretchy. With the right geometry (of the structure) and the fiber orientation CF can make for a nice spring, but a quick glance of that lmgtfy link showed a lot of bad designs with CF applied (poorly) ...and for RC toys.

I suspect that you should be looking for a structure that has gentle curves - looks like a rev-curve bow. Maybe a with an S-glass.

kaisen · 10-06-2014, 08:03 AM

The Corvette uses a carbon fiber and glass fiber reinforced plastic leaf spring

john70t · 10-06-2014, 09:23 AM

Quote:

Originally Posted by cgarr

...but because I had heated it and bent the end and didn't treat it right.

(if the picture is understandable...lol)
It may have been more about geometry, and how the layers in a sharp bend slide upon each other.

Always wondered why grease/etc isn't used in-between leafs.

cstreit · cstreit's Garage

Quote:

Originally Posted by island911

Yeah, those CF tail-wheel springs look great. ...for an RC toy. :-/

Seriously, CF has some low strain to failure ... the fibers aren't stretchy. With the right geometry (of the structure) and the fiber orientation CF can make for a nice spring, but a quick glance of that lmgtfy link showed a lot of bad designs with CF applied (poorly) ...and for RC toys.

I suspect that you should be looking for a structure that has gentle curves - looks like a rev-curve bow. Maybe a with an S-glass.

I gotta do ALL the work? I was giving him a starting point.

This is a Garret we're talking to. He won't actually BUY anything anyway. They shop, then ***** about the price, then go off and make it themselves every dammed time...

cgarr · cgarr's Garage

Ill just whip something out on the lathe then.

cgarr · cgarr's Garage

Didn't the Cessna 140 have a spring aluminum main gear? How about alum?

island911 · 10-06-2014, 04:09 PM

Quote:

Originally Posted by cstreit

I gotta do ALL the work? ..

Yes. Yes you do.

'cuz if you don't I'll be having to explain spring design and materials engineering.

Actually, I think that cashflyer has some good links there. - certainly this has been done successfully before.

If not, perhaps kachi will share his erector set and skillz.

cgarr · cgarr's Garage

It's kind of funny but I was at the Air Force museum for the air show weekend and leaving on Monday, we only had a 2 hour window to get off the field cuz they needed all the fire trucks etc to fly when it broke, they got the guys from the restoration hangar over with the fancy drill bits to cut me a new hole to bolt my wheel back on, if that didn't work I was just going to bolt some 2x2 wood to it and head home since all my stops had grass strips anyhow.

Worked ok but now it's gotta be fixed, no hurry it's all coming apart for new covering anyhow after 25 years.

island911 · 10-06-2014, 04:34 PM

just a stab at what you have, and what you want....

Steel - it's good stuff. Tough as hell, compared to other materials.

The thing is, the thickness defines how far the outer surface has to stretch, for any given deflection. So, say you replace it with aluminum... You make it roughly half again thicker, to get the same stiffness, and . .. the thing gets permanently bend on the first hard tap (because the outer Alum skin has to move so much further, for the same loading and deflection.) So, you make it wider... Are you ready for Aluminum to be 3x wider? (and weigh the same, btw) --I'll guess no.

Spring design, it can be a beotch.