Cobra trailer tongue.

I know its a snowballs chance in hell, but I'd be doing myself a disservice by not at least asking. Does anyone have a damaged cobra trailer with a good usuable tongue laying around?

Bryce
480-760-5610

On Sunday, April 28, 2019 at 10:24:08 AM UTC-7, Bryce Sammeter wrote:
I know its a snowballs chance in hell, but I'd be doing myself a disservice by not at least asking. Does anyone have a damaged cobra trailer with a good usuable tongue laying around?

Bryce
480-760-5610

https://wingsandwheels.com/cobra-tra...-1-seater.html

Been there.
The square one is stronger than the round one, which I'm guessing is the type found cracked. A used round one from a damaged trailer may already be damaged.
Jim

Ya I should of specified Im looking for the square style, or even just the square overrun bolted to the tongue. Just trying my luck before I plunk down an arm and a leg.

Can you post me a pic of what you need??
Cheers

Can't seem to post pics directly to the forum, Sent you a private message.

I am not a qualified mechanical engineer to tell you it would carry the load but I would think that you could buy what you need at any steel supply house knowing the length and width/height plus, importantly, the wall thickness. Best of luck, John (OHM)

On Monday, April 29, 2019 at 6:31:00 AM UTC-7, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
I am not a qualified mechanical engineer to tell you it would carry the load but I would think that you could buy what you need at any steel supply house knowing the length and width/height plus, importantly, the wall thickness. Best of luck, John (OHM)

A piece of cake, really. If you don't happen to have metal working and welding equipment, any good shop should be able to put it together. A galvanizing place may be harder to find. If you prime and paint instead, suggest etching the steel with dilute phosphoric acid before painting. Jasco Metal Prep is available at many hardware stores or paint supply places. Paint it on, hose it off.

On Monday, April 29, 2019 at 10:53:17 PM UTC-5, bumper wrote:
On Monday, April 29, 2019 at 6:31:00 AM UTC-7, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
I am not a qualified mechanical engineer to tell you it would carry the load but I would think that you could buy what you need at any steel supply house knowing the length and width/height plus, importantly, the wall thickness. Best of luck, John (OHM)

A piece of cake, really. If you don't happen to have metal working and welding equipment, any good shop should be able to put it together. A galvanizing place may be harder to find. If you prime and paint instead, suggest etching the steel with dilute phosphoric acid before painting. Jasco Metal Prep is available at many hardware stores or paint supply places. Paint it on, hose it off.

Thinking a little further on this, the square tube is bound to be a metric size. Getting an equivalent SAE sized tube may involve some effort. Slightly larger might not fit the internal brackets (or the AL-KO coupler). The better option is slightly smaller which will need some (welded on) thin shims to take up the slack - which the welding shop can handle (along with cutting off and reattaching the old jockey wheel bracket and underside's V shaped stand).

John OHM Ω

I have built about 35 sailplane trailers (before giving up on them as anything but a way to delay starvation) and have worked on a number of others, including Cobra, Komet, Eberle and any number of homebuilts. If you just want to replace the tongue (or Drawbar as it is sometimes called), you need to ask yourself a couple of questions:

"Do I want the basic square tube with a hitch only?" If so, go ahead and have a welding shop fabricate the thing. No problem with dealing with the simplified design.

If the question is, "Can I duplicate the AL-KO drawbar, including the surge brake mechanism, telescoping tongue, parking brake and jockey wheel mount? I am willing to bet that the efforts of a welding shop that could do it will end up being MUCH more expensive than just ordering one from Wings and Wheels. (Price on the drawbar with everything except the jockey wheel is $619.) With an average labor rate of $65/hour or more at many welding shops, the cost will most likely be a lot higher when you factor in the fabrication of all of the components. Remember the levers, damper brackets, sliding bushings, grease fittings, hitch, protective boot, surge damper, linkages and so on. This is not a trivial job.

As a matter of fact, the $619 is less than I expected, and I may replace the round tube on my 1981 Cobra with a new one. I certainly can't duplicate it for that!

On Thursday, May 2, 2019 at 4:29:14 PM UTC-4, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
On Monday, April 29, 2019 at 10:53:17 PM UTC-5, bumper wrote:
On Monday, April 29, 2019 at 6:31:00 AM UTC-7, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
I am not a qualified mechanical engineer to tell you it would carry the load but I would think that you could buy what you need at any steel supply house knowing the length and width/height plus, importantly, the wall thickness. Best of luck, John (OHM)

A piece of cake, really. If you don't happen to have metal working and welding equipment, any good shop should be able to put it together. A galvanizing place may be harder to find. If you prime and paint instead, suggest etching the steel with dilute phosphoric acid before painting. Jasco Metal Prep is available at many hardware stores or paint supply places. Paint it on, hose it off.

Thinking a little further on this, the square tube is bound to be a metric size. Getting an equivalent SAE sized tube may involve some effort. Slightly larger might not fit the internal brackets (or the AL-KO coupler). The better option is slightly smaller which will need some (welded on) thin shims to take up the slack - which the welding shop can handle (along with cutting off and reattaching the old jockey wheel bracket and underside's V shaped stand).

John OHM Ω

The current, square tube tow bar design (metric or imperial sized) can be improved by a lot. The hitch of a Cobra trainer is bolted on by two M12 bolts. The entire assembly is essentially coupled by friction. These bolts are not supposed to be in shear. Anyhow, one of the big draw-backs of square tubing is that the walls start to cave in when the bolts are being torqued.
Many moons ago, I did replace the rusted out tow bar of my trailer. I bought an equivalent stainless tube and drilled the holes for the hitch slightly larger than needed. Make sure not to drill through the tube's weld flash but 90* to it. Then I inserted short, tight fitting pieces of thick-walled SS-pipe trough the open end until they were aligned with the holes I drilled and TIG-welded them in place. Now I could torque the bolts holding the hitch to their appropriate value without deforming the square tubing.

Uli
'AS'