OOPS, one more question on airframes.................

[skyguynca]

So we know that the standard for a long time has been the square aluminum tube (6061T6 2x2x.125) assembled with cheek plates (6061T6 .125 thick), bolted together with 3/16 or 1/4 AN hardware and nuts, with washers............that is the really heavy part hardware.

There have been a few like Souza's Bandit that were welded up 4130 round tubing.

Is there any reason why if using square tube aluminum that you don't just TIG the square tubing together and then TIG the cheek plates in place to strengthen the joint and if you want a little more support use some 3/16 High Shear rivets or SS 3/16 pull rivets (coated in zinc chromate before being pulled into place)?

Surely there would be a significant drop in empty weight without all these 2 1/2 bolts and nuts in place?

David M.
San Jose, CA

 

[Vance]

So we know that the standard for a long time has been the square aluminum tube (6061T6 2x2x.125) assembled with cheek plates (6061T6 .125 thick), bolted together with 3/16 or 1/4 AN hardware and nuts, with washers............that is the really heavy part hardware.

There have been a few like Souza's Bandit that were welded up 4130 round tubing.

Is there any reason why if using square tube aluminum that you don't just TIG the square tubing together and then TIG the cheek plates in place to strengthen the joint and if you want a little more support use some 3/16 High Shear rivets or SS 3/16 pull rivets (coated in zinc chromate before being pulled into place)?

Surely there would be a significant drop in empty weight without all these 2 1/2 bolts and nuts in place?

David M.
San Jose, CA

It is my understanding that Igor Bensen wanted anyone to be able to build a gyroplane in his garage with limited tools and skills.

At the time most people lacked welding skills and it is harder to tell if it is a good joint with welded aluminum.

Properly designed riveted or bolted structures hold up well to the shaking inherent in a gyroplane and failure tends to be progressive allowing opportunities to find a problem before a catastrophic event.

 

[skyguynca]

Thanks Vance, so do you think that using large rivets to install the plates at each joint will be strong enough? Or bolts are still the only way to go?

David

 

[Vance]

When doing that kind of construction I would use multiple 1/8 to 1/4 inch cherry rivets depending on the joint.

Typically the holes are drilled undersized and reamed to size. In my opinion a drilled hole is not round enough.

A pneumatic puller is a worthwhile investment.

I agree using lots of long bolts is heavy.

The SparrowHawk used riveted plates for the drop keel and it was supposedly gone over by a qualified mechanical engineer I met there.

I was around Buckeye a lot for over a year and never saw a problem.

I saw one modified RAF there pranged in a very hard landing and all the joints held up well. It later became the first Sparrow Hawk and flew for years as a trainer.

 

[skyguynca]

Thanks Vance

 

[JEFF TIPTON]

You might want to review this _

https://flightsafety.org/amb/amb_jul-aug00.pdf

 

[skyguynca]

Thanks Jeff, I actually have this bulletin. I have over 30 years in aircraft (mostly helicopter) maintenance and repair. Blind rivets can be used with great success. In that bulletin, the basis of it was a mechanic specifically replaced solid rivets with cherry max rivets due to obstructions (hydraulic lines) in the repair prevented bucking solid rivets. I would have removed the lines and bled the system on reinstallation. Plus the Cherry Max rivets used while as strong as the the solid rivets, evidently had a higher setting pressure and initiated cracking in the holes. These cracks were also found in other Eurocopters who had made the same mistake of replacing the solid rivets with Cherry Max rivets. Many mechanics have made the same mistake though with solid rivets also by over driving them there by causing excessive pressure inside the hole in the material and initiating a or several small cracks. However I am sure you are already aware of this with your many years of experience in the maintenance field yourself.

 

[N7WWK]

Any thoughts on this Lord Fusor Crash Durable Structural Adhesive

Lord Fusor Crash Durable Structural Adhesive - 2098

Lord Fusor Crash Durable Structural Adhesive is a metal bonding adhesive that is good enough to replace all OEM single-component crash durable adhesives. It helps in restoring vehicles to the original condition before an accident. Use it for weld bonding, panel bonding, and rivet bonding of all...

www.autobodytoolmart.com

Tig welding seems like a good option to reduce weight, until you factor in the reduceed strength of the alloy from the heating it is recomended to retemper the aluminum. Mostbimpractical for home builders even with much experience in Tig.

The Lords Fusor structural adheasive it what most auto makers attach door hinges to the body, as well as other body panels.

It looks like it could be good option with riviets to hold parts in place until cure. I have persionally had door on my Chevy Express van blown open past the stop and slapped the front fender. No failuer of the adheasive joint. This is what gave me idea to investigate. This option but I would like imput frum more experienced builders. I'm currently in the process of building a Hornet.

But would like input before going down the wrong road.

 

[Greg Vos]

I own a vehicle that has a carbon fibre body, the chassis is a combination of aluminum and carbon fiber, the whole thing is glued together with almost no nuts and bolts, just the engine and gearbox is bolted in.
The manufacturer has convinced me this new marvel technology is far superior than my thinking ( welded metal frames) At first I was concerned, their punch line is....we are using aerospace technology now in cars.
That said I would not be comfortable with a gyro frame just glued together.
I assisted a guy about 18 years ago assemble a RAF 2000 and we riveted the main aluminum mast and frame, using a pneumatic riveting tool, It’s still flying today.

 

[Vance]

Any thoughts on this Lord Fusor Crash Durable Structural Adhesive

Lord Fusor Crash Durable Structural Adhesive - 2098

Lord Fusor Crash Durable Structural Adhesive is a metal bonding adhesive that is good enough to replace all OEM single-component crash durable adhesives. It helps in restoring vehicles to the original condition before an accident. Use it for weld bonding, panel bonding, and rivet bonding of all...

www.autobodytoolmart.com

Tig welding seems like a good option to reduce weight, until you factor in the reduceed strength of the alloy from the heating it is recomended to retemper the aluminum. Mostbimpractical for home builders even with much experience in Tig.

The Lords Fusor structural adheasive it what most auto makers attach door hinges to the body, as well as other body panels.

It looks like it could be good option with riviets to hold parts in place until cure. I have persionally had door on my Chevy Express van blown open past the stop and slapped the front fender. No failuer of the adheasive joint. This is what gave me idea to investigate. This option but I would like imput frum more experienced builders. I'm currently in the process of building a Hornet.

But would like input before going down the wrong road.

If you are interested buy a tube and dispenser and try it out on some test joints of similar materials to what you will be using.

In my experience to bond aluminum well a lot more preparation is required than what they describe. Aluminum oxidizes as soon as it comes in contact with the air and it is hard to get a good bond with oxidation.

 

[N7WWK]

I'm looking into structural adhesive with structural blind rivets looks like it would be strong.
Drilling holes with bolts can be bad connection depending on hole size. If set up in CNC for presise placement yes ok, drilled 1 on 1 with drill press not so much.

Slight misalignments in tubes and cluster plates buy fractions, leads to slop in the drilled hole. Adheasive and rivet seems like it would make up for slight improfections.

I have extensive experience in building, fab. mechanical drawing but I'm not aircraft engineer!

I'm looking for imput from others more informed and different points of view.

I have noticed that the Hornet plans from Don Shoebridge have some very screwy dimensions. Hole sizes do not relate to any known drill sizes somebwhare between inch, meteric, number and decimal. Leads for interpirtation. If using AN 3/16 sizes there way off. Slightly over size for 1/4" bolts. Don has done great work work in the design! Hats off to him for his great work.

Looking at all options!

 

[N7WWK]

If you are interested buy a tube and dispenser and try it out on some test joints of similar materials to what you will be using.

In my experience to bond aluminum well a lot more preparation is required than what they describe. Aluminum oxidizes as soon as it comes in contact with the air and it is hard to get a good bond with oxidation.

Yes I would defitnetly would do structural test like preping and gluing then trying to pull apart. My initial feelings is the aluminum tube would tear before adheasive failure.

 

[skyguynca]

[QUOTE="N7WWK, post: 1156902, member:

Tig welding seems like a good option to reduce weight, until you factor in the reduceed strength of the alloy from the heating it is recomended to retemper the aluminum. Mostbimpractical for home builders even with much experience in Tig.

[/QUOTE]


I learned about TIG welding airframes from Gene and Larry, the guys who designed and built the back yard flier, totally TIG welded. They actually had been doing it for years testing it out, and never had a failure

I also talked to several metallurgists and Engineers who backed it up. As long as you don't overheat the area of a critical Heat, which is really easy to tell with aluminum, it will naturally aged back to T5 in about 6 months.

I'll see if I can find it and post the pictures of an aluminum tube biplane that I welded together. All 6061 T6 every joint is welded no riveted gusset plates, and I flew it for 170 hours before I sold it. After was all welded up I followed Gene and Larry's advice and let it sit for 6 months. No cracks or failures.

David

 

[N7WWK]

[QUOTE="N7WWK, post: 1156902, member:

Tig welding seems like a good option to reduce weight, until you factor in the reduceed strength of the alloy from the heating it is recomended to retemper the aluminum. Mostbimpractical for home builders even with much experience in Tig.

I learned about TIG welding airframes from Gene and Larry, the guys who designed and built the back yard flier, totally TIG welded. They actually had been doing it for years testing it out, and never had a failure

I also talked to several metallurgists and Engineers who backed it up. As long as you don't overheat the area of a critical Heat, which is really easy to tell with aluminum, it will naturally aged back to T5 in about 6 months.

I'll see if I can find it and post the pictures of an aluminum tube biplane that I welded together. All 6061 T6 every joint is welded no riveted gusset plates, and I flew it for 170 hours before I sold it. After was all welded up I followed Gene and Larry's advice and let it sit for 6 months. No cracks or failures.

David
[/QUOTE]

Intersting since 6 months is do able most builders will take much longer than that to complete the project.

 

[skyguynca]

Actually, there's a lot of research has been done that's available on the internet now if you look for TIG welding aluminum. There was a guy that used to be on this form and he was on another airplane form that I was on , but I think he passed on a couple years ago. Anyway I'll look for his old posts and some emails we have back and forth about TIG welding 6061 T6 , he was an engineer who formulated the method for welding 7075 for space shuttle parts. I have it is recommendations he gave me on welding 6061 around here somewhere and it's pretty straightforward and he talks about how it will naturally aged in about six months back up to T5 and that he didn't feel that our homebuilt aircraft retempering would be needed to T6 because we don't impose that kind of stresses on our airframes

 

[N7WWK]

Actually, there's a lot of research has been done that's available on the internet now if you look for TIG welding aluminum. There was a guy that used to be on this form and he was on another airplane form that I was on , but I think he passed on a couple years ago. Anyway I'll look for his old posts and some emails we have back and forth about TIG welding 6061 T6 , he was an engineer who formulated the method for welding 7075 for space shuttle parts. I have it is recommendations he gave me on welding 6061 around here somewhere and it's pretty straightforward and he talks about how it will naturally aged in about six months back up to T5 and that he didn't feel that our homebuilt aircraft retempering would be needed to T6 because we don't impose that kind of stresses on our airframes

Would be great to see my initial plan was to Tig. If you find info you can email me n7wwk1 gmail or post. I natural aging is 6 months that would be great. I'm looking at likely 2-3 years min. For completion.

 

[skyguynca]

Will post it here for every one to read and email copy to you

 

[skyguynca]

Ok, here is one discussion between myself and Alan Latham. In the discussion it include Bert Holland. He designed a welded frame ultralight and a fully aerobatic welded aluminum frame biplane. I have his plans and had several conversations with him about welded aluminum airframes. Anyway this is the email that put me in contact with Bert Holland. This was on the Ragwing Forum Wed 11/20/2002 8:37 PM

David and All,

I've been following the aluminum tube talk and now have the info that I was wanting.

First off, I haven't been a big fan of the tube, gusset and pop rivet type of construction. I had visions of the rivets working loose and having a fuselage that after time you could shake the tail and watch the nose wiggle.

The first actual plane built this way that I saw was at the Gardner, KS fly-in.

Then when Dick Lemons brought his Neiuport to our fly-in at Lathrop I had more time to study this type of construction. I figured that if they can hold up with the weight of the VW up front and with the hours that this type of construction is racking up with out major problems I'm ready to try it...

Just must figure out on what and then finish some current projects.

The following info I got tonight from the gentleman that now sells plans for the Honey Bee and H-3 Pegasus that were designed by Bert Howland. Some history about Bert, he owned a aluminum manufacturing business and was an expert in the field. His two planes have fuselages built from 6061-T6 and is Tig welded.

We need to keep in mind that the Honey Bee is stressed for acro to the tune of +8 and -6 G's.

This is what I was told when I asked the question about 6061-T6 going back to O condition after welding. He said that the welding process does weaken the tubing in the area of the weld, but that in time the tubing age hardens back to it's original condition prior to welding, the time frame I was given was about a year for return to T-6. His reasoning was that by the time the project was ready to fly it would be back to T-6. About 6 months to T-5

So this means that David can't build a fuselage from welded 6061 unless he wants to look at it for what...judging from his current progress...about 11 and a half months... or if T-5 is ok then 6 months

I'd still love to know what happened to the Kopy Cat, the UL Pitts that also had a welded aluminum tube fuselage.

David, what are you going to build next month??? You got that Tig unit yet???


Al Latham

Lathrop, Mo.

 

[skyguynca]

This Email is from Classic Aero, Bert Hollands company

Bert Howland's answer to that same question, which he got quite often, was that the welded aluminum ages back to its original strength naturally, in less than a year year, approx 6 to 9 months, after it is welded. My fuselage was welded up in September 1991 and the aircraft flew in March 1992. The airframe has been subjected to normal aerobatic loads (ca. 4+ G) right from the beginning and there has never been any problem.



CLASSIC AERO ENTERPRISES

H. O. Malone
343 Wrexham Court
Hampton, Virginia 23669
757-851-2856

-----Original Message-----
From: David Mikesell [mailto:[email protected]]
Sent: Tuesday, December 03, 2002 11:42 AM
To: Classic Aero Enterprises
Subject: Question about welding aluminum

I have done alot of research about the welding of aluminum. Everything I find says that I will have to re-age the aluminum after welding, if it is not done then it will reach T4 or something in that area and be very brittle. What process was used to weld your fuselage? how long did it age? was it artificially aged? how many hours on your airframe? have you stressed your airframe repeatedly in flight? if so how much? any problems?



Please don't think I am in doubt, just collecting information before I build. Thanks again.



David Mikesell

 

[skyguynca]

Here are some emails from Gene and Larry Smith at Valley Engineering

Hello David, I'll tell you what we do and then I'll ask dad the engineer tomorrow to answer your question for me and reply again.. We weld our aluminum 6061-T6 and do not age it in any way. We weld .50 to 1/8" with mig and tig . We have never had a failure at or near a weld and do not worry about it. I'll ask dad what is the correct procedure and let you know. What thickness do you use? What # wire are you using 5356 or 4043 , .30 or .35 diameter ? Talk to you latter. Larry

David Mikesell wrote:

Hi my name is David MIkesell. I was referred to you by Monty Graves and he said you might be able to help me with my question. I understand you do some aluminum welding on airframes. I am thinking of building a H2 Honeybee which is a welded aluminum 6061-T6 airframe. I am using a mig welder and all is going fine. I am being told by half the people that I need to re-age the metal when done to restore the T6, the other half are telling me that I need to let it sit that it will re-age on its own and reach T6 again in less than a year. What is true? Any help you can give would be appreciated. ThanksDavid Mikesell
www.skyguynca.com
23597 N. Hwy 99
Acampo, CA 95220
209-609-8774

the next email was:


Hello, I talked to dad about it and this is roughly what he said. Ideally you would retreat the weld but it is usually near impossible to do on a plane, and aluminum will re-strengthen with time. The most important thing is to be sure to put the welds in non critical areas. We never weld across a spar or put the weld under tension.We try to put all welds under compression. That's our basic plan and as for the 5356 or 4043, we use 5356 in our wire feed welder with the long 12' lead because it is stiffer and easy to push. The 4043 is plenty strong it is slightly higher yield than 6061-T6. Congratulations on the 180 that is a very nice welder. Larry

David Mikesell wrote:

HI Larry, was wondering if you have given any more thought to the question. I did buy a TIG, the Miller Syncrowave 180, should I use the 5356 instead of the 4043? David Mikesell
www.skyguynca.com
23597 N. Hwy 99
Acampo, CA 95220
209-609-8774

-----Original Message-----
From: Larry Smith <[email protected]>
To: David Mikesell <[email protected]>
Date: Thursday, December 05, 2002 7:52 PM
Subject: Valley Eng Reply Hello David, I'll tell you what we do and then I'll ask dad the engineer tomorrow to answer your question for me and reply again.. We weld our aluminum 6061-T6 and do not age it in any way. We weld .50 to 1/8" with mig and tig . We have never had a failure at or near a weld and do not worry about it. I'll ask dad what is the correct procedure and let you know. What thickness do you use? What # wire are you using 5356 or 4043 , .30 or .35 diameter ? Talk to you latter. Larry

David Mikesell wrote:

Hi my name is David MIkesell. I was referred to you by Monty Graves and he said you might be able to help me with my question. I understand you do some aluminum welding on airframes. I am thinking of building a H2 Honeybee which is a welded aluminum 6061-T6 airframe. I am using a mig welder and all is going fine. I am being told by half the people that I need to re-age the metal when done to restore the T6, the other half are telling me that I need to let it sit that it will re-age on its own and reach T6 again in less than a year. What is true? Any help you can give would be appreciated. ThanksDavid Mikesell
www.skyguynca.com
23597 N. Hwy 99
Acampo, CA 95220
209-609-8774