water pipe vs DOM

One thing to consider: US made Gav pipe and Black pipe is not the cheap crap we get from China. Simple as that.

I bronzed some fittings to a plate for a lady. She bought them from a BOX store. The metal flowed easier than the bronze! It was like solder. So I went to the hardware store that buys USA. Those worked just fine and I could even weld them.

So quality depends on the supplier.

Mart>> >>

Back-gassing on 4130 is not required like on stainless. Want to see some nice 4130 Tig work?? Take a look at my Pegazair at

Sadly you can't depend on any supplier having the same product this month as they had last month. The next batch your hardware store gets might not be the quality US stuff either, Depends on availability and price.

Me too. And I got my copy in 1965.

Costin and Phipps wrote a great book, but take anything they say about welding or 4130 with a fat grain of salt. In fact, take anything said about it by anyone in 1962 with a grain of salt.

For some reason, the Brits were slow to accept fusion welding -- O/A or TIG -- for tube frames. They were slow to accept TIG, in fact. And they were slow to adopt 4130.

They may have had some good reasons, but my feeling, having studied a great deal about it over the past 50 years, is that they were a bit caught up in popular misconceptions. There are some such misconceptions floating around in the US, too, such as a need to pre-heat even thin tubing before TIG-welding it, and the supposed "grain opening" of 4130 if you braze it. These stories have been debunked.

Note that Brit homebuilt-aircraft builders aren't allowed to weld their own tube frames unless they're CAA certified welders. In the US, our EAA runs classes in welding 4130 with O/A and with TIG, and hundreds of aircraft have been built that way. I think we have a more extensive experience base with both the materials and the processes.

But I don't really know. I hope to get out to Jay Leno's garage again next year, and I'd like to ask Bernard, the garage manager, about it. He ought to know the whole story on the Brits. Also, the motorsports instructors at Lincoln and Miller should know very well what works and what doesn't.

BTW, we have an article coming up on when and where you can use lift-start TIG, later this year in Fab Shop. I think it will contain some discussion about 4130. ===============================================================

For five/six point roll bars and 10 point roll cages that get installed into production vehicles to augment the factory structures the NHRA requires

1-3/4" OD tubing with minimum 0.118" wall thickness for mild steel and minimum 0.083" wall thickness for 4130 chrome moly tubing. Mild steel welding must be "approved MIG wire feed or approved TIG heliarc process" and 4130 chrome moly welding by "approved TIG heliarc process". No grinding on welds permitted. Welds must be free of slag and porosity. For full tube frame vehicles there are more rules on OD and wall thickness depending on where in the frame the tube is installed. So for the five and six point bars and 10 point cages mild steel is most common, and if you want to save 75-100 lbs you can step up to 4130 for an extra $500-1000. Unlike roundy-round cars (NASCAR and dirt tracks) it is extremely rare for a drag racing car to hit anything so repairability isn't really a concern.

----- Regards, Carl Ijames

There is a great deal of Voodoo :-) Back in (maybe) the 1970's I was fooling around with SCCA Formula Ford cars and one of the local racers broke a rear axle and wanted it re-welded (the weld bead had sheered). I told him that I could do it in about an hour so he could get some practice in that afternoon and he instructed me that it MUST be Heliarc welded as that was much stronger. I took it away, ground out the old weld bead and rewelded it with arc, just as it had been originally, except I got 100% penetration :-). The guy was ecstatic and bragged about his "heliarced" axle to everyone he talked to.... and I got quite a bit of weekend work :-)

That's kind of interesting. I'd like to know how NHRA arrived at their rules for thickness and acceptable welding techniques.

There's a lot of talk about the problem with "cold starts" when welding 4130, which refers to MIG, primarily. But some kit planes have MIG-welded 4130 frames.

Over the years I've seen lots of comments and conclusions from people who build frames, but they rarely do any actual testing. I have a connection with a guy who works for a major welding-equipment company who supposedly has lots of testing data on tube frames for aircraft and cars. I have too much on my plate now to pursue it for an article, but I hope to get to it eventually.

Of all the metalworking processes I've reported on, welding is the most voodoo-ridden. Heat-treating is second.

No? I just saw quite a bit of conversation about it on the 4WD boards and assumed that it was required.

That cluster is terrifying to a newb welder like myself. Did he use a gas lens to get his rig down into there?

Saay, won't that plane be larger than the house, once it's winged? ;)

Those Corvair engines are smooth and sweet. I miss my old '62 convertibles. The red one was quieter at 100mph on the freeway in SoCal than Mom's Lincoln Continental. The previous owner was a Chippie (California Highway Patrol officer) who had sandbagged the front. Had it not been for that sandbag, we would have been light enough for my friend to have tossed us headfirst into a telephone pole after it swapped ends on him, despite my repeated warnings. I was in the back seat working on a sweet raven-haired beauty at the time, but I droves us home and Phil never drove another of my vehicles. Ahh, fond and freaky old memories...with glasspack mufflers on it, I'd shut off the engine with it in gear while approaching a friend walking down the street, then turn on the ignition just as the muffler was right next to them. All that unburnt gas in the muffler shot flames out the side as it exploded with a loud report. I never saw lumps form in their pants, but they sure were startled before they started cussing at me.

Yes, I believe a Gas lens was used

Wingspan will be roughly 35 feet with the tips installed

Did you hear it running on the test stand?? That 180 degree exhaust makes it sound SWEET!!!

I believe that urine from virgin females was once consider the best quenching fluid for tempering swords :-)

Their blood was supposed to be the best!

That's a nice quiet purr! You hear the tips of the prop more than the exhaust. It's probably quiet in the air, too.

One thing for sure,it'll sound like no other plane in the air.. Almost like a V-12. I suspect it will be the only vair in the air with

180 degree headers

I never could make out with a girl with another guy around. I always had to be alone with her to do that.

And the best part: That damnable 90-degree fan belt won't ever be necessary!