EEVblog #854 - B52 Bomber Automatic Astro Compass Teardown

[broz]

Also....wonder if this computer is Turing Complete?? 

[mbqwerty]

That's what those synchros are for, getting input from the MD-1, and probably also operating the display. In searching around I've found some other systems where the mechanical bits were mounted directly behind the panel driving the altitude/azimuth display via direct mechanical linkage
 I'm thinking that springy bit that winds alternately between the two spools is some sort of integrator, or other math function. Might be useful to measure the sizes of the two spools with calipers and see what if any ratio exists between them - they are definitely not the same size. And in the time lapse you can see it winding up on one spool then reversing and going back to the other one.

I know old steam engines (such as those on early railroad locomotives) used a couple of spinning balls with a spring keeping them close together, and as the engine sped up, the centrifugal force compressed the spring which allowed the balls to rotate further apart which in turn closed a valve. This, if my recollection is correct, acted as some sort of regulator. Perhaps the springy bits here serve some similar functionality?

P.S. My apologies for the crudity of my explanation, have no idea what the technical terms are for everything, but hopefully it made some sort of sense!

That would be a governor on a steam engine.

[rrinker]

That's what those synchros are for, getting input from the MD-1, and probably also operating the display. In searching around I've found some other systems where the mechanical bits were mounted directly behind the panel driving the altitude/azimuth display via direct mechanical linkage
 I'm thinking that springy bit that winds alternately between the two spools is some sort of integrator, or other math function. Might be useful to measure the sizes of the two spools with calipers and see what if any ratio exists between them - they are definitely not the same size. And in the time lapse you can see it winding up on one spool then reversing and going back to the other one.

I know old steam engines (such as those on early railroad locomotives) used a couple of spinning balls with a spring keeping them close together, and as the engine sped up, the centrifugal force compressed the spring which allowed the balls to rotate further apart which in turn closed a valve. This, if my recollection is correct, acted as some sort of regulator. Perhaps the springy bits here serve some similar functionality?

P.S. My apologies for the crudity of my explanation, have no idea what the technical terms are for everything, but hopefully it made some sort of sense!

That would be a governor on a steam engine.

Right. Railroad locomotives didn't have that (except in a weird way Doc Brown's modified time machine steam locomotive) but stationary steam engines did. I've seen it called a "fly weight governor" or a "fly ball governor". Invented by James Watt: https://en.wikipedia.org/wiki/Centrifugal_governor
In the B52 computer, it's possible that band things does some sort of regulation. If you watch the speeded up part where Dave points out the one wheel changes direction, you'll see the same thing happens with those pulleys and the band, it winds up on one side, then it reverses and winds back to the first one. The two pulleys appear to be different sizes though, and as you get near the end of the band winding on the big one, it makes the small one spin even faster  I thinking some sort of calculation like a line approaching an axis sort of thing. Asymptote, that's the word I was looking for.

[broz]

That would be a governor on a steam engine.

Right. Railroad locomotives didn't have that (except in a weird way Doc Brown's modified time machine steam locomotive) but stationary steam engines did. I've seen it called a "fly weight governor" or a "fly ball governor". Invented by James Watt: https://en.wikipedia.org/wiki/Centrifugal_governor
In the B52 computer, it's possible that band things does some sort of regulation. If you watch the speeded up part where Dave points out the one wheel changes direction, you'll see the same thing happens with those pulleys and the band, it winds up on one side, then it reverses and winds back to the first one. The two pulleys appear to be different sizes though, and as you get near the end of the band winding on the big one, it makes the small one spin even faster  I thinking some sort of calculation like a line approaching an axis sort of thing. Asymptote, that's the word I was looking for.

Right! My bad, thanks guys

[SeanB]

We used to take apart the old Mirage autopiloys out of airframed being upgraded, as they contained the right selection of gears, synchros, resolvers and such needed to fix other avionics. Basically a big brass meccano set with all the various plates doing assorted functions. The dead ones still were usable even if the coils or contacts were burnt out, I used to gently strip them to get the bearings out, along with the stator coils on some, to fix cooling fans that were faulty. Sealed, epoxied together assemblies, but with a little determination you could take it apart and use the certified parts again. Everything had a part number and serial number on it, even the individual gears, and in some cases even the rotor and stator of a resolver.

Did send GK a nice little sine/cosine pot for him to use, he probably has more use for this, relic from some auction scrap medical research equipment.

[chris_leyson]

Reminds me of an old Smiths Industries heading indicator, at least I think it was a heading indicator, picked it up one Saturday from C.R. Marks in Wyndham arcade Cardiff, must have been 45 years ago. It was stuffed full of 2-phase and 3-phase resolvers and synchros most of them marked 28V 400Hz, and loads of anti backlash gears and tiny ball races. Had that distinctive sort of rubber and varnish smell that you get when you crack open a piece of 50's vintage kit. The 3-phase resolvers and synchros were a thing of beauty with slightly splined stator and rotor slots.

[Kaptein QK]

... I'm thinking that springy bit that winds alternately between the two spools is some sort of integrator, or other math function. ...

Having seen those before I think that is a multi-turn spring with rather constant torque within its operational range.

[stejep]

I can't understand how someone came up with this and how they calculated all those gears etc.

It reminds me of the old electro mechanical adding machines that my dad brought home for us to pull apart and have fun with.
They had an electric motor that drove all gears and leavers. They were a work of art.

[jefferyrowan]

What would be the reason for doing this by mechanical means? In the 60s this would seem trivial to do with transistorized op amps. It would be more reliable, lighter and faster.

The B-52 was built in the 50s and upgrading existing equipment is a long slow process. I was involved in upgrading F-4 UHF radios from solely tube type to a transistor type in 1979. I should note that the new radio was much lighter so we had to add the weight back in for balance so lighter is not always better. Nor is faster unless you update the entire avionics system to synch with a faster equipment.

[Brumby]

There's one little thought that has always maintained an appreciation for the rigours of aviation certification...

If something goes wrong, you can't exactly pull over and call a tow truck.

[jh15]

I maintain a community radio station and it is like fixing an airplane while flying... Live DJs 24/7/365.

[Don Hills]

I maintain a community radio station and it is like fixing an airplane while flying... Live DJs 24/7/365.

Dead air isn't quite the same as dead dead. 

[SeanB]

There's one little thought that has always maintained an appreciation for the rigours of aviation certification...

If something goes wrong, you can't exactly pull over and call a tow truck.

Been there, done that...... Hanging out the door with the flight engineer and looking down under the wing while the gear was cycling, because the light did not go green to show locked. Landed very carefully when we ran down to fumes... Got back in after the fixing, and we carried on around the circuit, got to my destination 7 hours late. Walked in and was asked where I had been, replied the plane broke down and we had to get out and push.

[Brumby]

 

Did you check the tyre pressures while you were at it?

[ale500]

Walked in and was asked where I had been, replied the plane broke down and we had to get out and push.

 

[rm31859]

Hello all, I'm new to the website. I ran across it while researching a piece of Air Force B-47/B-52 avionics. I am a Ham operator and i collect vintage electronics. Especially radio equipment but I like anything electronic. I have been in to electronics since I graduated college in 1979 and discovered Radio Shack. I built practically every kit that RS had and a lot of other stuff over the years. The reason for this post is that I purchased a piece of avionics from an Ebay dealer that no one seems to be able to identify. The item is labeled "control, In Flight, T-19-A". The Ebay item # is 263471893522 and the listing title is " Air Force Special Weapons Control T-19/B47 Bomber" The pictures aren't the best in the world but hopefully they will suffice. In the photos you can see a toggle switch marked "INC set and DEC set" I believe these mean Inclination and Declination but I can't be absolutely sure. the two ON/OFF toggle switches are run to relays and then to the large connector on the back as is everything else. This leads me to believe this is just the control head for whatever system this is designed for. If anyone has any info on this item o the system it was used in, Please let e know. Thanks.