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What was the item from the February issue?

You may receive a couple of thousand letters like this, so I hope you don’t feel like this is “piling on.” I do not know the aircraft type the tank may have been built for. However, this tank predates any method for welding sheet aluminum. The best way to convert sheet aluminum to a tank, would be riveting. This is not an unusual fuel tank, given its date of manufacture. Other sheer metal joints could have been used, but they would be difficult to seal. The riveting process, inherently pulls the sheets of metal, together with incredible tightness. I was astonished to read, (or why it was even riveted ) in a magazine dedicated to the construction of aircraft, from all the decades of flight.

John F. Olson
EAA # 310789
Goodyear AZ

P.S. Call the TIG welding wizards at Miller Electric, in Appleton, for the first date that sheet aluminum could have been welded.


I would assume it was built for the Martin model YB-10 and YB-12 bombers. I found the information in a book I have. There was apparently no YB-11 bomber. The YB-10 was really an advanced bomber in its day. It was also preceded by the Boeing YB-9 bomber. The tank shown must be too small to be the main fuel tank at only 16.4 gallons considering this was a twin-engine bomber. Could it have been a header tank located near the port or starboard engines? Or could it have been the tank that stored the engine oil for one of the radial engines. This might be more plausible.

I found some additional information on a website. http://home.att.net/~jbaugher2/b10.html

Jim Boxmeyer
EAA #114981


The fuel tank is an interesting artifact. First, the easy part. What type of aircraft? Martin YB-10, early 1930s bomber.  


Why riveted design? The primary aviation aluminum alloy in use at that time, 2017-T4, is not weldable. Also could be 2024-T3 (unweldable as well), which was gaining widespread use by 1933. Basically, welding of aluminum alloys (3003, 5052, 6061, etc.) was not commercially possible until the 1940s.  

The rolled seams and tight rivet pitch (spacing between each rivet) are indicative of the state of sealant technology at the time. The first fuel-resistant Thiokol-type sealants didn’t appear until WWII. 

The other hardware on the tank appears familiar, except for the fasteners attaching the fittings (probably bronze) to the inside of the tank. They look like the driven side of a HiShear, which caught my eye because I thought those were not used until WWII. Also would be an unusual application for HiShear fasteners. 

Tom Knott


The item in the February 2007 issue of Sport Aviation, EAA’s Attic shows a fuel tank reported to be manufactured by Glenn L. Martin Co. I would like to submit that this tank was manufactured about 1934 as part of a contract to deliver 48 Martin Model 139’s, a twin-engine bomber, to the USAAC. Fifteen of which were designated as YB-10s and 33 were YB-12 &YB-12As. Numerous improved variants were produced and delivered to the USAAC in 1935 & 1936. Several were converted to twin floatplanes and numerous ones exported to six foreign countries.

A more likely possibility maybe that it could have been from an experimental Martin Model 132 developed in 1932, from which the Model 139 was derived. This is based on the model number of the tank “YB-10-12.” The prefix “Y” was added in 1929 to the Army method of designating model & type. The “Y” indicated a “service test status of a new model at a time when a limited quantity was being evaluated in squadron use before the placing of a production order.” The ”B” of course designated “Bomber,” which is what the both models were. There also is the old & familiar USAAC identification of a five pointed (white) star inside a circle and a (red) ball inside the star located on the nomenclature plate--the military symbol in use at that time. I have no knowledge as to which aircraft the tank was in but it must have been one tank of several. It would take as lot of fuel tanks with 16.4 gal to supply two radial engines of over 700-hp each. Could it have been an “engine oil” tank? The later varients had a range of over 2000 miles.

This is deduced from information from Janes Encyclopedia of Aviation, 1980/1989, Portland Press, Crown Publishers, (page 622). Also from Classic Military Biplanes, Peter M. Bowers, 1965, Modern Aircraft Series, Sports Car Press, Crown Publishers, (page 13). 

Hope you can verify this info. 

Earl W. Burns
EAA #146647


In response to your inquiry in “Attic” I believe this tank was an oil cooler tank used on top of the engine nacelle for the YB-10-12 Martin Bomber, offered to the Army Air Corps in response to a request to bid. 

The subsequent XB-10 prototype led to a contract for 48 production aircraft. (Source: American Combat Planes, 3rd edition, Roy Wagner.) 

A long shot would be that this was a hydraulic tank for the retractable landing gear. 

I am an old guy, former Air Corps military pilot, with an abiding interest in all aircraft. I am a docent at the Glenn L. Martin Museum in Maryland. 

I am turning over my copy of the February ‘ 07 issue and a copy of this letter to a much more knowledgeable person, Stan Piet, Archive Director at the Martin Museum.(martineer@aol.com)

He may provide more accurate info on the tank. 

Frederick J. Trumpbour
EAA #0493899


Are you sure the tank you show in the Attic in this month’s magazine is a fuel tank? Could it be an oil tank ? The Martin B10 and B12 bombers, which in 1933 development would have been YB-10 and YB-12, had two radial engines which is why this might be more like an engine oil tank. This would also support the “YB-10-12” Model number on your data plate. The radials used a dry sump oil system, so they’d have to put the oil in an external tank. Radials weren’t exactly “conservative” in their oil usage. Considering they were for relatively long range missions, I’d think they’d carry a considerable amount of oil as well. 

 They built a reserve fuel tank that fit in the bomb bay, but this was 365 gallons not a mere 16 gal. Seems too small to be a fuel tank for anything that Martin built in 1933. The fittings are all pipe plugs too, which seem to be more appropriate for an oil system. 

The B10 was the first all aluminum-riveted monocoque fuse aircraft. The rivet work would seem appropriate for the time and project. 

Harold Sutphin
EAA #0397547 

P.S. - I started working for Martin Marietta (now Lockheed Martin) in the early 80s, so this was before my time (sorry). We don’t keep documentation around that long. I’m not sure the museum in Maryland would even have the prints for the B10/B12, but that would be the right place to look. That or maybe someone can poke his head around in the bomber in Dayton.


I love this new feature, and I’m pretty sure I can help you with your first mystery. And, I’m sorry to say, I think this puzzle is way too easy.

The gas tank you pictured in the February issue is said to be made by the Glenn Martin Co. in 1933, and the model designation is YB-10-12. But you don’t know what plane it might have belonged to.

Guess what. In 1933, Martin began production of its YB-10 and YB-12 bombers. These were the earliest production variants of the groundbreaking B-10 line, the first all-metal mono bomber with retractable gear and enclosed bomb bay. It was faster than any pursuit plane of its time and led to the development of all the famous and more familiar bombers of World War II. Sadly, the B-10 itself, a huge advance for its day, was obsolete by the outbreak of hostilities.

I think it’s 99.99% unlikely that Martin just happened to make an odd gas tank in 1933 that just happened to be given the same model designation as its biggest production model at the time, yet somehow had nothing to do with that plane. Clearly, YB-10-12 means that this was a production part for both the YB-10 and YB-12 model bombers Martin produced.

Now, that leaves the mysteries of why it was made of riveted construction and what the heck it was for. I don’t have any evidence for this, but due to the tank’s small size (and the B-10 was a very big plane for its day), it can’t have been an auxiliary tank for engine fuel. So it probably was for an auxiliary system, and I would guess that it was to fuel cabin heaters. The B-10 originally held a crew of four (later reduced to three); pilot, copilot and gunners, in separate, open compartments. It was not pressurized. But it was the first high-altitude, level bomber, so there would have been a need for some warmth up there. You can see in the picture that there are several line inlets.

Three are visible, aside from the filler neck, and there is probably a fourth on the opposite side. I’m guessing these would have been connected to separate cabin heaters in different parts of the plane. And I would guess the tank held kerosene, not gasoline.

But why was it riveted? Well, as said, this was the first all-metal bomber, and the whole plane must have had about 100,000 rivets or more. So Martin must have employed a whole lot of riveters, and must have been totally tooled and geared up for mass-scale riveting. Stamping and welding was probably foreign to them. In fact (and this shouldn’t be too hard to research) it’s possible that no one knew how to weld aluminum in those days. So riveting, to a company introducing a production line of big metal planes, must have seemed like second nature. The tank is probably made of the same aluminum they used to make the plane’s members.

I would bet a few dollars, or a beer with Paul Poberezny, that if you asked the Army to look up the contract number and part number, somewhere in the vaults they would find a specification for a “fuel tank, metal construction, containing a minimum 16 U.S. gallons, to fuel cabin heaters in contractor’s Model YB-10 and YB-12 bombing aircraft,” or words to that effect.

Keep ‘em flying,

Jim Price
EAA #754845


As you indicate, most of the information needed to identify the item is on the data plate. This is the oil tank for the left engine of most of the twin-engined bombers of the Martin B-10 / B-12 series of airplanes built during 1933. Army Air Corps contract W535AC5665 covered the production of YB-10, B-10, B-10A, YB-12, B-12 and B-12A bombers. Part number R103063 is shown in engineering drawings as an oil tank, and is shown on drawing number 103061 as the tank for the left engine. 

As for the riveted construction, my guess is that this is because of the state of the art in welding aluminum. The maintenance manual for the B-10B, which used a larger oil tank, says there is a sealing compound used on the riveted joints. It also cautions against using steam to clean the tank, to prevent softening of the compound, thus causing leaks. 

Larry Wilson
EAA #269418 
[Technical Information Specialist]
[Archives Division]
[National Air and Space Museum]


There is not much mystery about “what type of aircraft carried the tank.” The Glenn L. Martin Company of Baltimore designed its Model 123 bomber in the early 30s. It was the first all-metal monoplane bomber in U.S. service, and the first that was faster than the pursuits of the day. The design was tested as the XB-10 by the Army in 1932, and a production contract awarded. Starting in November 1933, Martin delivered 14 aircraft, denominated YB-10. This would appear to be from the 12th ship.

John D. Lyon
EAA #121817, Chapter One


Greetings from Down Under 

I would suggest that it is from a Glenn Martin YB-10 bomber built in Baltimore in 1933. [see below].


The first 14 aircraft were designated YB-10 (33-140/153). They were powered by 675-hp Wright R-1820-25 engines. They differed from the prototype primarily in having transparent sliding canopies fitted over both the pilot’s cockpit and the rear gunner’s position, a concession to the 200 mph-plus speeds that could be attained. The rear cockpit was modified to accommodate a radio operator in addition to the gunner. Armament consisted of a 0.30-inch Browning machine gun in the nose turret, a 0.30-inch gun in a flexible position in the dorsal position, plus a 0.30-inch machine gun in a tunnel position in the fuselage floor behind the bomb bay to guard against attacks from below. The internal bomb bay could carry two 1130-pound bombs or five 300-pound bombs. There were provisions for an external shackle under the right wing for a single 2000 pound bomb. The YB-10 could be distinguished from its successors by the presence of an oil cooler scoop on top of the engine cowling.
The first YB-10 was delivered to Wright Field in November of 1933. Most of the YB-10s were based at March Field in California with the 7th Bomb Group until December of 1934, when it re-equipped with B-12s. The YB-10s then remained at March Field with the 19th Bomb Group. In a demonstration of their reliability, and efficiency, ten YB-10s undertook a survey flight to Alaska in July of 1934. 

Keep up the good work of promoting aviation. 

Best regards
Randal W McFarlane
EAA  #0327565


That fuel tank is a work of art, it is interesting that you have selected it to show.

My thought as to what it is. The Model YB-10-12 fairly well clears it up. The Glenn L. Martin Company manufactured the B-10 Bomber beginning in 1932 and continued thru 1936. To increase fuel range additional capacity was installed and the Bomber was re-designated B-12A. Your beautiful example was most likely part of the package.

The B-10/12 series was an absolutely gorgeous design. One example still exists and is in The Air Force Museum in Dayton, Ohio.

Best Regards
Bob Arnold
EAA # 37362
WBA # 522 


That ‘gas’ tank is maybe an oil tank for like pratt/whitney 500 hp wasp engine--used on bellanca skyrocket and boeing 247 etc in that period US CIVIL AIRCRAFT JUPTNER VOL 5/6



I had this whole thesis working that the Glenn Martin tank was for oil not fuel. But there would have to be returns above the full level and why the threaded boss midway up the left side facing us in the picture, and why the DUAL bosses on the front (or back?)

It would have to mount as shown in order to fill it to capacity and wouldn’t the outlet (s) have to draw from the lowest point?

So, are there extensions from the two bosses to the bottom internally? Pickups? That’s a lot of trouble to make for only 16.4 gallons. That wouldn’t get you far in a 1933 aero engine. So, is this a “header tank”? mains and aux’s feeding the header tank prior to reaching the engine?

Maybe it’s an auxilliary oil tank to be used in a long distance flight? Added to allow oil to feed to the aircrafts main oil tanks in flight? Returns wouldn’t be required. Two outlets to two oil tanks? Twin-engined aircraft?

Another thought is that possibly it’s not aircraft in nature. Tractor? Marine use? Automotive?

Did Martin branch out in other directions to earn revenue? I doubt they were raking it in Aviation endeavors.

It doesn’t appear to be used either? All the bosses are plugged. Why would you bother if this was a pull off?

Did anybody take the filler cap off and give it a whiff? That might determine contents.

John Underwood, where are you when we need you? 

Tom Leatherwood
Avlite Aviation, Inc
Beech 18 specialists


I suspect you’ve already received a bunch of E-mails on this subject, but the tank whose photo you published on page 128 of the Feb 2007 Sport Aviation comes from, no doubt, a Martin YB-10 or Martin YB-12 bomber. The airframes were the same but they differed in engine type. What you’re looking at is likely an oil tank, not a gas tank. 16 gallons would be an appropriate size for an R-1820 or an R-1690. 

Walt Holm

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