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Martin-Baker M.B.1,2 and3

cluttonfred

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Random question...per the old Martin-Baker MB-2 web site and other sources, the MB-2 had an automatic rollover pylon: "A crash post was fitted, which automatically extended to minimise structure damage and injury to the pilot in the event of a nose-over landing." Here's a pic with the post extended (source).

1593706929093.png

I think a few other 1920s-1930s designs had automatic rollover protection, but does anyone know how such a system actually worked in practice? Was it just a weighted tube within another tube that extended and locked when subjected to negative G? Was it controlled manually by the pilot in some way? Maybe tied in to the flaps?

Thanks and regards,

Matthew
 

Schneiderman

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Random question...per the old Martin-Baker MB-2 web site and other sources, the MB-2 had an automatic rollover pylon: "A crash post was fitted, which automatically extended to minimise structure damage and injury to the pilot in the event of a nose-over landing." Here's a pic with the post extended (source).
I think a few other 1920s-1930s designs had automatic rollover protection, but does anyone know how such a system actually worked in practice? Was it just a weighted tube within another tube that extended and locked when subjected to negative G? Was it controlled manually by the pilot in some way? Maybe tied in to the flaps?

Thanks and regards,

Matthew
The subject of a patent applied for by Martin in 1935 and granted the following year. The patent does not specify the mechanism to activate the pylon other than to say that 'means is however provided to raise them to an operative position when the machine is alighting"
 

cluttonfred

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Thanks very much, Justo Miranda and Schneiderman, so not automatic at all but manually activated. The text says both electrical and pneumatic, so I imagine it was a pneumatic valve opened by an electric solenoid. Cheers, Matthew
 

Schneiderman

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Two mechanisms were suggested in the patent, one pneumatic the other spring loaded. The illustrations are of an early version of the MB2, but that does not necessarily mean that either were actually fitted to the aircraft
Image1.jpg Image2.jpg
 

cluttonfred

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Here is Martin's U.S. patent. I does strike me that unless there was some means of raising the device automatically there was a real risk that it would not have been raised when needed most. Ideally, it would have been most valuable if the default position had been up and locked and it was only retracted above certain speed so it would have always been ready during takeoff and landing.
 

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riggerrob

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Dear Cluttonfred,
Many modern light airplanes incorporate fixed roll bars inside their canopies. Note the triangular roll bars in Richard Van Grunsven's early RV-4, then compare them with the strong canopy bows installed in the latest RV-14.
Even many 1930s-vintage light airplanes (e.g. Chilton DW-1) have roll triangles concealed within their plywood headrests. Many of those triangular, steel-tube roll-over bars have flat steel plates welded on top to prevent sinking into soft ground.
 

gruff

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Great thread gentlemen.

Does anybody have pictures of the laminated main spar of the MB3?

I once found a large RC Model book with only one interesting (to me) picture, and did not buy it...
It was a full page showing two modellers posing with their very large, service painted MB models;an MB2 and an MB3. I think the models were shown topside in their full span, a unique sight.
 

gruff

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Thank you Schneiderman.I never realized, or forgot, about the laminated part. It seems to have a line of rivets all around for sure.
 

riggerrob

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Dear Gruff,
It may not be clear from the photographs, but laminated spars are common. While a spar may only have a single-layer cap near the tip, progressively more and thicker layers are riveted or glued on the closer you get to the fuselage. Rivets get longer as they get closer to the wing root.
The alternative is machining the spar to reduce thickness as you approach the tip ... a complex machining process.
 
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gruff

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Thank you riggerrob. I had not realized from drawings that thickness, as well as height, changed.
 
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