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I am building a Windwagon/Hummelbird. The Builder's Manual for the Windwagon calls for the use of primer between pieces to be bolted or riveted. However this was written way before Corrosion X became available. Would the Corrosion X alone give the airframe the protection or should I still primer the mating surfaces.
I'm ignorantly assuming you're using 6061-T6 to build your plane. If you want protection, you might mix up some Cortec and brush it on the mating surfaces of parts. Pretty simple, and minimal weight addition as opposed to soaking the entire innards with Corrosion X.
I would use a good Zinc Chromate Epoxy primer.
A mix of 6061 and 2024 are the alloys being used.
corrosion x has to be periodically reapplied to maintain it's effectiveness.
I wouldn't use anything because aluminum has built in corrosion protection. Having the plane last 100 yrs would be about 80 yrs more than what I need at this point.
Another good choice would be Zinc Phosphate. Doesn't have the carcinogen threat of Zinc Chromate. I always have a couple of spray cans on hand, and got them from ACS.Quote:
Originally Posted by vaflier
Two schools of thought on corrosion protection. One is that all faying surfaces will have moisture showing up by capillary action so you had better provide protection by priming the members before joining ( zinc chromate).
The second is that by blocking or displacing the moisture from entering the joint, you will avoid corrosion (Corrosion X). If you live, hangar and fly in a dry environment that precludes moisture from developing, you might leave joints bare. Much depends on where you operate.
Given that I live in Wisconsin I think I had better prime the surfaces. I don't forsee my renting a hangar, rather tieing down save for extended periods when I may not fly where I will bring the plane 'home'.
There are 60 yr old spam cans that have never seen a drop of primer, stored outside more than inside and they are still going strong.
If you use Corrosion X don't plan on painting the airplane for the next couple of years.
All it takes is the onset of corrosion and it will propagate by itself. Trying to stop it can take much effort and expense, I'd opt for preventing it in the first place.
Then again, there was a run of Cessnas in the '70s where the company scrimped on the anti-corrosion prep; these have suffered a lot of corrosion.Quote:
Originally Posted by martymayes
Case in point. Take a look at these three homebuilts:
http://www.wanttaja.com/wickham.jpg
The blue single-engine one in the middle is the Wickham "A" ("Bluebird") that first flew in 1955, and the twin in the foreground is the Wickam "B", which flew about 1967. Both are all-metal, 2024, I believe. Though they might have been 7075. The third airplane is some obscure wooden type. :-)
Anyway, the designer/builder of the first two was Jim Wickham, a configurator for Boeing Commercial Airplanes. It was his opinion that airplanes built from aluminum did not need additional corrosion protection, and neither of his airplanes were primed.
The Bluebird (single-engine) was restored in the ~90s. Didn't hear of much anti-corrosion work needed. However, the Bluebird was an active airplane through most of its life, and was mostly hangared, I believe. The A&P who does my Condition Inspections did the restoration (and he parks the plane across the hangar row from my Fly Baby).
The Model B (twin) was donated to a museum in ~1980, who parked it outside for 10-15 years until a chapter member bought it. He found massive corrosion in the wings.
So....it's basically a crapshoot. If I were building something from 2024, *I* would prime the thing. And as Falcon21 says, if you apply Corrosion X during construction, don't expect to be able to paint the outside of the airplane. That stuff will weep through various holes (as it's designed to) and ruin any chance for paint adhesion on the outside.
I like Bob's recommendation for Zinc Phosphate.
Ron Wanttaja
One caution. Double check this but I have seen written that once a Corrosion-X is into a seam, paint will not longer stick. If that is true, primer is a better option. Corrosion-X after painting the exterior.
Bust of luck,
Wes
I would use Cor-Ban 35 . Boeing puts it on their planes and I used it at the airline I worked for . It is spray on or brush on and is a see thru rose colored texture . It dries and you can see thru it .. just a slight color . I think it is the best . Sky Geek sells it .
Cor-Ban video is on YouTube . Just put in "Cor-Ban" and the info will come up .
This is the kind of bs info that the internet experts love to spread on forums. The only “built in” protection aluminum has is IF it is Alclad. If there is the tiniest scratch that alclad is compromised. Drill a hole and guess what, you’ve compromised the alclad. In reality the aluminum will out last you if untreated, but the big guys like Boeing prime everything. In critical areas they are assembled with wet primer. All external skins on pressurized aircraft have sealant applied. Built in protection indeed.Quote:
Originally Posted by martymayes
2024 corrodes very quickly with the least provocation. Aluminum is a very reactive metal.
Drill a hole, put a screw in it, add liquid and wait. If the screw is stainless the aluminum will start to disappear. If the screw is cad plated, the plating will first corrode away; when it is gone, the aluminum will start to corrode. Google "Galvanic Corrosion".
In Australia near the coast, they say; "you can hear the Cessnas Fizzing" as they corrode away.
One turboprop I flew required a strip and inspection every three years due to corrosion issues; made of 2024.
Corrosion proof your project! You will not be sorry.
Yes, that's what I said. No need to take it out of context.Quote:
Originally Posted by Paulie123
Geography makes a difference. When I lived on the Gulf Coast, a helicopter operator had it down to a science. They knew exactly how often a refub was needed and they knew when they put a helo in service how many yrs it would last. ACF-50 treatments were a routine maintenance item.Quote:
Originally Posted by la4
On the other hand, 20+ y/o fish spotters flying Cessna 172's over the same water would rack up 20,0000 hrs with the standard Cessna corrosion package - nothing but paint - which was sparse after 20 yrs of abuse. They did get a routine ACF-50 bath as well.
Where I live now, as long as you don't drive your plane down the highway in the winter, not much salt exposure.
Ron, wasn't the Cessna filiform corrosion in the '70's partly caused by Cessna during their switch to modified polyurethane finishes?Quote:
Originally Posted by rwanttaja
Guys, thanks for the input. I believe I will takeRon Wanttaja's advice and prime spars and skin joints. Once I paint, I will go the Corrosion X route. I will be little bitty and want to be seen.
martymayes I believe that you are correct about the polyurethane paint. About 1977 we has a Cessna 180 painted with that stuff and about 6 months we had an unbelievable amount of filiform corrosion . It had no corrosion with the factory paint . It looked like worms all over the C-180 . This was in Florida where there is high temps, high humidity and salt air .
Metals corrode according to the galvanic series. Those high on the scale are most reactive when coupled with materials lower on the list. Magnesium is very high and gold is lowest. All other engineering materials are in between. Aluminum is below magnesium so if these two are in contact with an electrolyte (water, especially salt water), the mag corrodes first. If you look at alum alloys like 6061 or 2024, the 6000 series has mag as alloying constituent. Since mag and alum are close on the galvanic series, there isn't too much activity. With 2000 series, the alum is coupled with copper as alloying element, which is lower on the scale, so the reactivity is higher. Therefore, 2024 has higher galvanic activity and corrodes easier. So you have to protect 2000 series more than 6000 series. By cladding the reactive alum alloy with pure alum ( cladding) you reduce the galvanic activity at the surface and hopefully reduce corrosion.
I did a Google search to see if there were ever plans for the wickham B didn't see anythingQuote:
Originally Posted by rwanttaja
just double checking here if wickham ever made the plans public or donated them to a museum or university?
thanks
Michael
Wickham never made his plans public; don't know what happened to most of them. May have donated them to Seattle's Museum of Flight or the Aeronautical department at the University of Washington.Quote:
Originally Posted by North_roll
At the time of his death, his wife donated his partially-completed Wickham Model F to the local EAA. I believe the plans came with it. Parts (most of the fuselage and partially-completed wings) are stored in the hangar where EAA 441 meets, don't know where the plans are. Some of the members of EAA 26 and 441 are looking into completing the aircraft, so they probably have them. It was designed for two Mazda rotary engines.
The guy who owns the Bluebird also now owns the Wickham Model C "Sunbird", a small single-seat cantilever-wing airplane made of wood. VW-powered. The Wickham D and E were similar. Wickham sold the D before it was even completed. He was performing spin testing with the Wickham E (Sunbird II) and ended up having to bail out. He was 68 at the time.
Interesting guy. I found a write-up about him, that I did for my chapter newsletter about 14 years ago. It's attached.
Ron Wanttaja
Quote:
Originally Posted by rwanttaja
Thanks for for the info, the article is a very good read. I looked up the Seattle flight museum. Once they open their doors again I'll give them a call and see if they have the plans. Sometimes you get lucky with this sort of thing.
im already involved with a few building projects, but I'm learning Solidworks and digitizing old plans like these would be good practice. Start with the rudder... Then elevator...etc...may never finish but it's good practice .
Every year someone on some aviation site asks....what about an experimental twin??...
now we have somewhere to point them...hopefully someone with a good nose for this will uncover those plans..
thanks
Michael
The best anti corrosion to use is Corban 35 made by ZIP Chemical . Boeing uses it on all of their aircraft and airlines use it where needed at their overhauls . It can be be bought is spray cans or bulk to spray or brush . Sky Geek has the best price. You Tube it . I use it on my A/C .