Chromoly Fuselage Welding

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My own little brother, bless him, has his mind made up to build his own flying contraption....a Super Cub from scratch and blueprints. A little background on him is that he is 27 years old, a mechanical engineer, just finished his masters degree but has been working in the mechanical engineering field for a couple years. He's definitely smart and like many of the old school engineers, he's always working on something/experimenting with something to make it better/stronger/faster/lighter so he does have it in him to actually build stuff rather than just design stuff on a computer that isn't practical. Anyway, he's not a welder. He can mig weld, but never had much need to weld so he isn't proficient at it, yet, never had a "major" or critical welding project. Back when the Super Cubs were in their hayday they were being oxy-fuel welded together. They are made up of thin walled 4130 and there is quite a bit of welding involved, imo. There are actually quite a few guys building or have built their own SC's and most are probably lacking the welding backgrounds that many here have. There are many advantages to building your own experimental aircraft under FAA regulations, the ability to do your own wrenching and modifications, build the exact plane you want, you can do your own annual inspections and maintanence which will greatly reduce the cost of owning a plane as well as the satisfaction and "cool factor" of building your own plane. There's also good support through the EAA and builder groups.My question to the forum isn't whether or not he should be doing this, he's already made his mind up. But, what would be the best method to do this. Under the FAA's 51% rule for this plane to be an owner built experimental aircraft you have to fabricate a lot of things yourself and certain criteria have to be met. Building his own fuselage will make big strides toward meeting these criteria.My question is what would be the best welding process for him to use for welding thin wall chromoly tubing, tig or oxyfuel? What steps should he take to ensure good welds that aren't prone to cracking? If TIG welded with some 70 wire used as filler would it need heat treating due to the HAZ? Any tricks, tips or advice I should give him for the welding?Here's a site that documents a SC build, turned out really nice, he used oxy-fuel.http://www.supercubproject.com/Powcon 400SM2-PD60 wire feedersMiller XR controlAlumapro push/pull gunSpeedglas 9100xBFH
Reply:Definately 70=6 or -s. maybe even 80 series, but not 4130 filler unless you want to go to Post Weld Heat treatment.   He certainly has chosen a tough project to start with and as such since there is no pulling over and lifting the hood I would recomend as a minimum, a community college welding course and some serious hands on one on one time with a highly experienced welder and lots of practice before he welds the first joint on the fuse.  Once he gets there I would thouroughly inspect each weld and have some radiographics done on things like the motor mount and control systems.   Once he gets started ask him for some pics and post em up too.BobI'm spending my Kids inheritance, I dont like him that much anyway!!!!!!Enuff tools to do the job, enough sense to use em.Anybody got a spare set of kidneys?  Trade?
Reply:If it were me I would tig weld with ER70-S2, no post treating or anything like that to deal with. I have built a few tube space frame race car chassis out of 4130 chromoly tubing and this filler, welds like a dream.
Reply:I know one or two guys who have built their own experimental aircraft. From what I understand EAA has a lot of good information available on this topic. The guys I knew both used O/A and I believe that process is still recomended by EAA for doing what you want to do. I suggest you post this question up with the EAA. They have a lot of experience with tig and aircraft and can probably point you in the right direction from experience.Almost everyone I've known who works on aircraft takes a different view towards things than say the guys on a 4x4 site. Things like welds are never just "good enough" or "it's ugly but it holds". That's probably due to both the stringent inspections the FAA enforces on aircraft in general as well as the fact that when the wings fall off you plane it usually makes for a very bad day... since you are usually in it at the time..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:If this was me, I'd personally make myself go and test for certification on tig welding tube or pipe before starting this project. I'd not start this project till I could pass this test.Just for personal satisfaction.70S-2 and tig all the way.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:x2 on snoeproe's comments.  2 experienced pilots were killed here in the Dayton area over the weekend.  They crashed their reproduction wright flyer into the woods.  Reports in the news mentioned that people nearby heard some kind of problem with the plane's engine.My point is that experimental aircraft have killed a terrible number of people over the years.  (John Denver springs to mind too)By all means, encourage your brother to try.  But push him to do everything within his power to minimize the risks involved.  To me that means learning to weld with enough skill that he can pass a weld test on these thin walled 4130 joints.  It means buying the best filler metal and tube to work with, and accepting nothing less than perfection in the manufacturing of his plane.Will agree with previous posters that Oxy-acetylene is the tried and true method for making these welds.  They can be done with TIG, although the sense I have is that TIG welding these joints is just as demanding, if not more so.  ER70 filler metal is the right grade for welding 4130 without heat treatment.I'd shy away from the racing and offroad forums for advice on this project.  Steer your brother towards listening to people with real world experience with building airplanes.I know that Dave Powelson, who posts to this forum, has some experience fabricating for the aerospace industry.  Hopefully, he'll post and offer some useful advice.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:I would think that this topic must have been covered many times in Internet forums dedicated to home-built aircraft.  That's the place I would look.Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:70S2 and tig are preferred nowadays. In this case though, it helps to weld a bit slower than you normally would as not to shock the area around the weld with the drastic temperature difference.That being said, I got a buddy who welded his Helicycle helicopter with oxyacet and it turned out great. Find a local EAA chapter and talk to those guys. They will give you tips and most of the time you can find someone who knows what they are doing to come out and help ya. Hope your brother knows the amount of work ahead of him. He would probably be better off looking on barnstormers for a kit that someone has given up on. Saves a lot of time and money. I've owned experimentals since I was 17 (as well as some certified aircraft) and it has been a great experience.Good luck to your brother
Reply:As mentioned the EAA has technical advisors that can help him out. As for learing to do the job right, stick with aviation sources. The EAA offers classes on aircraft welding called sport-air workshops. They are also offered on the other aspects of building. As for welding method, Either Tig or O/A is fine. Tig being "drawn down" after welding so a torch will be needed reguardless. Also the original "Cubs" were not 4130, they were 1020 mild steel with 4130 used in some areas. Nowdays most use 4130 throughout. Again I strongly suggest you work with someone well versed in aviation, and not just welding. All the BS out there in the hot-rod or racing world means nothing from a technical perspective. If you want I can help get you steered in the right technical direction and get you to the right technical advisor in your area. I gave up posting technical tidbits in forums since the "internet welding experts" took over, feel free to PM me and I will get my contact info to you.Last edited by makoman1860; 08-02-2011 at 10:17 AM.
Reply:Best for 4130 is ER80S-2. Been using that for years on fuselages. You can also check out the following site  http://www.tigdepot.net/articles.phpWyatt Swaim is a recognized expert with TIG welding. Excellent article on fuselage welding in the above pointer
Reply:Tell him to build a bike frame first. He will learn a lot about tube fitting, welding, and his own abilities.Ian TannerKawasaki KX450 and many other fine tools
Reply:Originally Posted by makoman1860As mentioned the EAA has technical advisors that can help him out. As for learing to do the job right, stick with aviation sources. The EAA offers classes on aircraft welding called sport-air workshops. They are also offered on the other aspects of building. As for welding method, Either Tig or O/A is fine. Tig being "drawn down" after welding so a torch will be needed reguardless. Also the original "Cubs" were not 4130, they were 1020 mild steel with 4130 used in some areas. Nowdays most use 4130 throughout. Again I strongly suggest you work with someone well versed in aviation, and not just welding. All the BS out there in the hot-rod or racing world means nothing from a technical perspective. If you want I can help get you steered in the right technical direction and get you to the right technical advisor in your area. I gave up posting technical tidbits in forums since the "internet welding experts" took over, feel free to PM me and I will get my contact info to you.
Reply:[QUOTE=merlewagner;538670]Best for 4130 is ER80S-2. Been using that for years on fuselages. You can also check out the following site  http://www.tigdepot.net/articles.phpWyatt Swaim is a recognized expert with TIG welding. Excellent article on fuselage welding in the above pointer[/QUOTWyatt Who? Im not even going to touch the filler debate. So much of what is "taught online" is biased by the authors connection to either  a welding machine company or a welding filler metal company its not even funny.
Reply:Thanks for all the advice and offers of guidance. This will be a long term project, obviously, and which ever method he ends up doing safety and quality are going to be the #1 priority. Before he starts any of the welding part of his project I think it would be a good idea for him to take one of the fuselage welding classes offered through the EAA, more so than through a local college since the courses are designed to be specific to what he's wanting to do. The EAA seems to be a great asset to the home builder. I too have been wanting to do such a project but don't have the room to do it (brother just bought a house with 2 huge barns and a workshop so he's got plenty of room), but I've decided that I'm going to join the EAA if for no other reason than to see some of what others are building.Powcon 400SM2-PD60 wire feedersMiller XR controlAlumapro push/pull gunSpeedglas 9100xBFH
Reply:Good Plan, Dont forget, if you come to either Oshkosh or Lakeland for the conventions, there are classes taught all day on construction methods, hands on. I spend all week at OSH teaching welding ( aluminum and steel ) and the students really get a lot out of it. Classes specific to what you are building, taught by experienced and educated people that have done exactly what you want to do. Doesnt get any better than that ( plus its free ).P.S. except for the lincoln electric guys, none of them are in the aviation hobby, they are just salesmen and will say anything to sell a machine, kind of sad actually.
Reply:Don't even consider building anything that flys without getting a copy of AC 43.13 Acceptable Methods and practices. I'm sure you can get a copy at[URL="http://www.aircraftspruce.com"]It will cover not only welding but all processes of aircraft building and repair. It is consider the bible of aircraft work. Look for AIRCRAFT INSPECTION, REPAIR & ALTERATIONS under book at that website. It's about $22.Last edited by tresi; 08-02-2011 at 07:55 PM.Tough as nails and damn near as smart
Reply:Originally Posted by A_DAB_will_dox2 on snoeproe's comments.  2 experienced pilots were killed here in the Dayton area over the weekend.  They crashed their reproduction wright flyer into the woods.  Reports in the news mentioned that people nearby heard some kind of problem with the plane's engine.My point is that experimental aircraft have killed a terrible number of people over the years.  (John Denver springs to mind too)By all means, encourage your brother to try.  But push him to do everything within his power to minimize the risks involved.  To me that means learning to weld with enough skill that he can pass a weld test on these thin walled 4130 joints.  It means buying the best filler metal and tube to work with, and accepting nothing less than perfection in the manufacturing of his plane.Will agree with previous posters that Oxy-acetylene is the tried and true method for making these welds.  They can be done with TIG, although the sense I have is that TIG welding these joints is just as demanding, if not more so.  ER70 filler metal is the right grade for welding 4130 without heat treatment.I'd shy away from the racing and offroad forums for advice on this project.  Steer your brother towards listening to people with real world experience with building airplanes.I know that Dave Powelson, who posts to this forum, has some experience fabricating for the aerospace industry.  Hopefully, he'll post and offer some useful advice.
Reply:True...but you need to start with quality from the beginning. I've had two engine failures in my time in the air. Both were the same engine. One was due to the gas station where I got my gas switched over to ethanol blend and never posted anything or said a word about it.The second was a crank seal that went south. Leaned out the cylinder and seized it. Both had perfect landings, but that was in a CGS Hawk and that plane was absolutely amazing. I wouldn't have wanted to experience the same thing in my tri pacer. Lesson learned...no more 2 strokes.Aside from the story, lots of solid advice. Talk to those who have already learned the hard way and get help. There's always a number of members in EAA chapters willing to give their time to help out those interested in GA
Reply:Originally Posted by makoman1860Good Plan, Dont forget, if you come to either Oshkosh or Lakeland for the conventions, there are classes taught all day on construction methods, hands on. I spend all week at OSH teaching welding ( aluminum and steel ) and the students really get a lot out of it. Classes specific to what you are building, taught by experienced and educated people that have done exactly what you want to do. Doesnt get any better than that ( plus its free ).P.S. except for the lincoln electric guys, none of them are in the aviation hobby, they are just salesmen and will say anything to sell a machine, kind of sad actually.
Reply:Originally Posted by tresiDon't even consider building anything that flys without getting a copy of AC 43.13 Acceptable Methods and practices. I'm sure you can get a copy at[URL="http://www.aircraftspruce.com"]It will cover not only welding but all processes of aircraft building and repair. It is consider the bible of aircraft work. Look for AIRCRAFT INSPECTION, REPAIR & ALTERATIONS under book at that website. It's about $22.
Reply:Originally Posted by makoman1860Good Plan, Dont forget, if you come to either Oshkosh or Lakeland for the conventions, there are classes taught all day on construction methods, hands on. I spend all week at OSH teaching welding ( aluminum and steel ) and the students really get a lot out of it. Classes specific to what you are building, taught by experienced and educated people that have done exactly what you want to do. Doesnt get any better than that ( plus its free ).P.S. except for the lincoln electric guys, none of them are in the aviation hobby, they are just salesmen and will say anything to sell a machine, kind of sad actually.
Reply:Remember John Denver crashed because only 1 of 4 wing spar bolts were installed before flight.( it was trailered with the wings off)I bet the wright flyer crashed just because it flies like crap !   Barely controlable by todays standards !
Reply:And this applies to the post how?
Reply:He would be wise to make his own printed checklists for construction, inspection, and maintenance. There is good reason for that because they remind and reinforce. If you are interrupted you need not rely on memory. Take notes too. Blank logbook or whatever you like. Do it like you are doing it for someone else and it will work well for you.I wrenched OV-10s/F-4s/F-16s for 26 years and learned early on that no matter how much experience you have precise tech data and written logs are your friends.
Reply:Originally Posted by jethroRemember John Denver crashed because only 1 of 4 wing spar bolts were installed before flight.( it was trailered with the wings off)I bet the wright flyer crashed just because it flies like crap !   Barely controlable by todays standards !On the "how to weld chromoly" debate.  There are plenty of opinions available on the Internet.Lincoln Electric says ER80-S2, no pre-heat needed on thin tubing.The home built plane people say gas welding is still the best.  Gas essentially pre-heats and cools much slower.  Pretty sure those guys still use 4130 as filler.   A NO-NO for TIG welders!!!!There is good reason to believe the ER70-S2 is in fact better for TIG than ER80.ER80 diluted with 4130 makes for a good weld if your grind down the weld and do a bend test.  In otherwords, strength wise it seems to be a good match.ER70 will typically be under matched in strength, but it is easily made up with a bigger bead.  The extra heat you put in to form the bigger bead only helps in slowing the cooling down.  The slower cooling widens the HAZ and keeps the stress concentrations near the joint down.  Hopefully the rest of the tubes are just in tension anyway...Consider wrapping the tubes in blankets to keep the heat in.I believe the AWS now has an FAA approved technique for 4130.  Its worth asking.Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Originally Posted by con_fuse9On the "how to weld chromoly" debate.  There are plenty of opinions available on the Internet.Lincoln Electric says ER80-S2, no pre-heat needed on thin tubing.The home built plane people say gas welding is still the best.  Gas essentially pre-heats and cools much slower.  Pretty sure those guys still use 4130 as filler.   A NO-NO for TIG welders!!!!There is good reason to believe the ER70-S2 is in fact better for TIG than ER80.ER80 diluted with 4130 makes for a good weld if your grind down the weld and do a bend test.  In otherwords, strength wise it seems to be a good match.ER70 will typically be under matched in strength, but it is easily made up with a bigger bead.  The extra heat you put in to form the bigger bead only helps in slowing the cooling down.  The slower cooling widens the HAZ and keeps the stress concentrations near the joint down.  Hopefully the rest of the tubes are just in tension anyway...Consider wrapping the tubes in blankets to keep the heat in.I believe the AWS now has an FAA approved technique for 4130.  Its worth asking.
Reply:Having a masters degree doesn't make your little brother qualify for welding air craft frames.......This should be done by a guy with experience in that field and certs....  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock