EEVblog #854 - B52 Bomber Automatic Astro Compass Teardown - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: February 24, 2016, 02:20:29 am
content: What's inside a Kollsman Instrument Corporation MD-1 Automatic Astro Compass mechanical analog computer from a B52 Bomber?Part of the star tracker inertial navigation system that calculates the altitude and azimuth.Thanks to thehttp://thegeekgroup.org/

author: Skimask
author_rank: Super Contributor
timestamp: February 24, 2016, 02:26:23 am
content: Oooooo.....There's an old friend (or is it mortal enemy?) I haven't seen (or worked on) in a loooooong time.

author: RobertoLG
author_rank: Frequent Contributor
timestamp: February 24, 2016, 03:14:34 am
content: man, that was cool!!! teardown, i just wanted to se that thing working, really nice

author: Someone
author_rank: Super Contributor
timestamp: February 24, 2016, 03:25:03 am
content: The synchro is an early way of communicating an angular position to a remote location:https://en.wikipedia.org/wiki/Synchro

author: rrinker
author_rank: Super Contributor
timestamp: February 24, 2016, 03:27:19 am
content: That is some serious electro-mechanical porn right there. Amazing piece of engineering - all those fine tooth gears, those beautiful helical ones on the one shaft that was being turned.. wow. This turned out to be a MUCH better teardown that I originally thought it might after seeing it in the Mailbag. I may be an EE by degree but I do love me some high quality mechanical bits like this - goes back to tearing apart old clocks when I was a kid and manually turning the gears to figure out how the escapement movements worked. I think I would have been there all day myself turning the various gears and seeing what interacted with what on this thing.

author: Lightages
author_rank: Unknown
timestamp: February 24, 2016, 03:39:11 am
content: It looks like it is computing the differences between two spherical coordinate systems.

author: ez24
author_rank: Super Contributor
timestamp: February 24, 2016, 03:42:44 am
content: Questions and commentsWhat happens to items like this? Will they end up in a museum some day? Seems Sidney could have a nice electronics museum some day from the stuff people send you. "Dave's Electronic Museum"If there is a Keysight scope giveaway - my vote goes to whoever sent this to you. They deserve it.Enjoyed this video.

author: rrinker
author_rank: Super Contributor
timestamp: February 24, 2016, 03:44:24 am
content: 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 linkageI'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.

author: jh15
author_rank: Frequent Contributor
timestamp: February 24, 2016, 04:57:45 am
content: I'm going to look up some co-workers from Kollsman. The inventor of the first practical aircraft altimeter.I worked there during this time, and being in EE land, I was amazed at designs coming from experts in other fields, especially mechanical genius.I bet some of this was headed by S. K. just for privacy stuff.Hint, later in life he was quite deaf, and used to shoot any more than 4 squirrels at his bird feeder from the kitchen window with a shotgun. His wife didn't appreciate it.I have the solder tape hanging over my bench as I speak, and is easy to remove with a big ass soldering iron.We used helium for leak checks, but believe most of our instruments were just nitrogen charged.We also sold very expensive infrared environmental chamber windows made from turkey oven wrap and aluminum rings designed by this guy to middle east country.Now I am sure to be put on watch list.

author: Monkeh
author_rank: Super Contributor
timestamp: February 24, 2016, 05:19:15 am
content: Quote from: ez24 on February 24, 2016, 03:42:44 amThere isn't a single person there who'd know what to do with one.And it'd probably walk off like the last, much less valuable scope.

author: jh15
author_rank: Frequent Contributor
timestamp: February 24, 2016, 05:25:25 am
content: I'd sure know what to do with one, I hate buying Tek 7000 series scopes just to have something nice.

author: edy
author_rank: Super Contributor
timestamp: February 24, 2016, 05:46:35 am
content: From:http://www.glennsmuseum.com/bombsights/everything.htmlQuoteIt looks like you would press some buttons which would help you line up sites with some stars and while you were doing this the same inputs would be delivered to the inside of this mechanical computer. The internal mechanism would line up as well in a certain way and the resulting position of cogs and wheels and such would give you some numerical output that represented your position?That curved part that slides along the other curved track and bobs back and forth is almost like a sextant itself. Here is a good primer:http://astronavigationdemystified.com/Fascinating!

author: mtdoc
author_rank: Super Contributor
timestamp: February 24, 2016, 07:21:27 am
content: That was a really cool teardown!I need to show this to my dad and get his take on it. He worked on theInertial Navigation System for the MX misslein the 70s and 80s. Cool stuff.

author: dexters_lab
author_rank: Unknown
timestamp: February 24, 2016, 08:39:52 am
content: great video Davewould expect there should be a mix of motors and syncro resolvers in there to get get the data in and out of the unit, this would have to move to and sync with the actual position of the aircraft and then lock inhttps://en.wikipedia.org/wiki/Resolver_(electrical)at a guess it looked like it should be mounted with the connectors (top) facing up, could be the resistance you noticed when it's in the wrong orientation might be deliberate, there could be a clutch arrangement to lock the system up if it sees too much pitch and roll?wonder too if there could be multiple inputs, ie. would you not have to fall back on dead reckoning / gyros if you cant position from the skymap?i would be tempted to remove the hacked up base, mount it and use an arduino or something to make it slowly operate as an ornamental piece.

author: Smalltalk-80
author_rank: Newbie
timestamp: February 24, 2016, 09:15:23 am
content: 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.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 24, 2016, 09:32:08 am
content: Quote from: Smalltalk-80 on February 24, 2016, 09:15:23 amSolving multi - vector equations in realtime was far and away from the newfangled transistors in those days.The most difficult thing was to make the system work over the poles. The primary mission of B-52 was to fly over the pole and deliver nukes to Russia.

author: janoc
author_rank: Super Contributor
timestamp: February 24, 2016, 09:50:01 am
content: Quote from: wilfred on February 24, 2016, 09:38:51 amB52 was designed in the 50's before transistors were usable (they have been just invented in the 1947!). The transistors didn't become meaningfully usable until sometime in the early 70s or so. Usable solid state opamps were still a long way off.Also don't forget that this was designed to not only deliver that nuke on target but also to withstand the blast and bring the bomber back home. The EMP blast from a nuke would probably obliterate the period solid state electronics, leaving the bomber blind.It was good enough and worked sufficiently reliably so that they didn't feel the need to replace it. There has been plenty of similar gear on the period planes - e.g. the famous WWII Norden bombsight or the remotely controlled defensive gun turrets. All driven by mechanical analog computers, using motors and selsyns (synchros).

author: Smalltalk-80
author_rank: Newbie
timestamp: February 24, 2016, 10:13:59 am
content: The M1 was only introduced in the mid 60's. Until then it seems sekstants where used, to which this seems to be a direct equivalent. By then electronic transistorized analog computers doing stuff like this was pretty trivial tech.The Space Shuttle core memory was because it was non violate first and foremost, and then also because it has natural radiation hardening. You'll have to link me to somewhere saying that the Shuttle also used a mechanical flight computer. That wouldn't make any kind of sense. Especially since it is a research vessel and can use radio reliably for the same means.The bell around the mechanical computer was already plenty shielding for the heights the B52 flew, and could have been made smaller and lighter if electronics where used.The thing with EMP could be a probable explanation but there are still plenty of electronics in a B52 that would have been affected. Also sheilding could have been employed.Edit: Minuteman 1962https://en.m.wikipedia.org/wiki/D-17B#And that was a digital unjamable computer, for a missile.I still think ananalogelectronic computer would be better in a B52 since it is essentially a stream processor and have to react very quickly and reliably for many years.Analog computery stuff is still used in many many places. It's just not fashionable to talk about. ;-). An example is the tracking in a harddrive. A digital system would be to slow and inaccurate to react there.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 24, 2016, 11:58:56 am
content: The D-17B was probably very highly classified and even the Apollo mission wasn't allowed to use it and had to come up with the Apollo computer.Also D-17B was purely for inertial guidance.Besides it was large and heavy and the Apollo mission needed three (minimum two) separate computers so this called for the development of a separate computer from scratch which won't expose any of the details of the nuclear missiles. They used the first integrated circuits in any computer.As B-52 was very likely to fall into enemy hands it was unthinkable to put the latest technology on it. In case of nuclear exchange not many of them were expected to return anyway. Besides, it was expected to accumulate very many flight hours because they were loitering in the air over Canada 24/7/365 ready to set off for Russia at moment's notice. In this environment a mechanical system is easier to maintain by the existing personnel maintaining the other flight instruments.

author: LPaul
author_rank: Contributor
timestamp: February 24, 2016, 01:37:31 pm
content: Quote from: mtdoc on February 24, 2016, 07:21:27 amLooks impressive. Crazy that they still rely on that in the 21th century. Guess there is not that much information available on this ?

author: Arne
author_rank: Newbie
timestamp: February 24, 2016, 03:25:40 pm
content: Highly interesting ! Cant wait to see it calculateThe Link provided by Roberto (http://www.prc68.com/I/MD1.shtml) offers an overview of patents relating to the compass. This one (I guess you all already have it printed and hanging over your bench) looks just like it describes the computer you got:„ Pat. 3042296 Celestial Data Computer, V.E. Carbonara & E.D. MacDonald (Kolsman Inst Corp), Jul 3, 1962, 235/61NV“https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US3042296.pdfMaybe you can relate the input/output sections of the patent to those of your computer (Input: “Input shafts of the data computer 150 mainly: L.H.A. (local hour angle) shaft, latitude shaft 152 and declination shaft 158”; Output: Altitude and Azimuth (!) – hence “Computer Altitude/Azimuth”)So there should be three main input motors (?) … can’t see it on the video unfortunately, but it looks like you’ve been turning the output shafts …All the best from GermanyArne

author: Kjetil
author_rank: Regular Contributor
timestamp: February 24, 2016, 03:27:54 pm
content: Beautiful machinery.This video explains many of the mechanical/mathematical functions:

author: liviuo
author_rank: Newbie
timestamp: February 24, 2016, 04:20:09 pm
content: Quote from: Kjetil on February 24, 2016, 03:27:54 pmThank you for sharing the video link !

author: Mashpriborintorg
author_rank: Regular Contributor
timestamp: February 24, 2016, 05:04:50 pm
content: I have already seen a star tracker dome for sale on ebay, can't remember the final price it went for. And Dave speaks about the sonobuoys in the video, I already had the opportunity to take one apart, it was a old one form the 70, in very bad condition, but still, something you don't have the chance to take apart every day !

author: rrinker
author_rank: Super Contributor
timestamp: February 24, 2016, 05:21:49 pm
content: Great find. These old training films are always good information. It seems like a mess of gears and shafts until you see how it breaks down into simple easily understood bits as shown in the video.

author: Kjetil
author_rank: Regular Contributor
timestamp: February 24, 2016, 06:23:39 pm
content: Quote from: rrinker on February 24, 2016, 05:21:49 pmYeah, there's lots of great info in them. It's pretty amazing to see how simple the various functions actually are when you translate them to mechanical function, and a great way to visualize the functions they actually perform

author: dexters_lab
author_rank: Unknown
timestamp: February 24, 2016, 06:43:28 pm
content: Quote from: Mashpriborintorg on February 24, 2016, 05:04:50 pmi'm guessing the star tracker part went for $$$ then?would be nice to see the guts of one...

author: andy_cristea
author_rank: Newbie
timestamp: February 24, 2016, 09:19:17 pm
content: Quote from: Kjetil on February 24, 2016, 03:27:54 pmThanks for the video!

author: philpem
author_rank: Frequent Contributor
timestamp: February 24, 2016, 09:25:58 pm
content: Quote from: jh15 on February 24, 2016, 04:57:45 amInteresting! I've got a Kollsman (actually Negretti & Zambra, made under licence from Kollsman) L31523-10-009 tachometer sat on my shelf - I picked it up in a junk shop as a curiosity.It actually seems to run up OK, but one of the three "needles" makes a hell of a grinding noise when the motor is powered, and the needle bounces all over the place, so I suspect it's had a bit of a bump and needs some mechanical TLC.Looking at it again there's a bit of a bead around the back... part of me is tempted to strip the paint and see if that's a solder bead like Dave's thing. Maybe I can open it up and fix it.Quote from: jh15 on February 24, 2016, 04:57:45 amI don't suppose you happen to know what alloy it is?Good to know it's removable with the Mk1 Bigass Soldering Iron though. I'll see if either my gas iron or my Metcal are man enough to pull it off.Cheers,Phil.

author: f4eru
author_rank: Super Contributor
timestamp: February 24, 2016, 10:02:43 pm
content: Cool "Heavy metal" computingsimilar stuff :https://www.flickr.com/photos/64683169@N00

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 24, 2016, 10:13:30 pm
content: QuoteAluminium or Magnesium.Magnesium is kinda fire hazard in a war plane but it is light and rigid. There are also aluminium alloys which are brittle enough to chip when hit. Al-Ti or Al-Li alloys for example.

author: EEVblog
author_rank: Unknown
timestamp: February 24, 2016, 10:34:10 pm
content: Quote from: HAL-42b on February 24, 2016, 10:13:30 pmThat was my first guess and I came to the same conclusion, I doubt they'd use magnesium.

author: philpem
author_rank: Frequent Contributor
timestamp: February 24, 2016, 11:02:15 pm
content: Quote from: EEVblog on February 24, 2016, 10:34:10 pmI wasn't aware that there were any aluminium alloys which would melt at normal soldering temperatures. But then again, we have 60/40, and the melting point of both tin and lead is much higher than the melting point of 60/40 solder...

author: RobertoLG
author_rank: Frequent Contributor
timestamp: February 24, 2016, 11:17:07 pm
content: I don't know if I'm saying some BS here, but maybe there are some titanium parts in this thing?

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 24, 2016, 11:50:14 pm
content: Quote from: philpem on February 24, 2016, 11:02:15 pmWell... both Aluminum and Magnesium are completely impossible to solder. The only thing that would make them solderable is some sort of plating for the solder to stick to.

author: ajm8127
author_rank: Contributor
timestamp: February 25, 2016, 01:16:27 am
content: You can "solder" aluminum and other metals. It is called brazing and the only difference is the temperature at which the filler metal melts. Copper, brass, aluminum, nickle, iron, steel and stainless steel (and probably others, I'm not an expert) can all be brazed. A brazed joint is usually stronger than a soldered one. I think there is some association between melting point and yield strength.That old military training video was awesome. Of course you can use a high level language to program a computer to solve a problem, but I think using a machine so very elegant, albeit necessitated by the technology of the times.I would love to see a tear down and subsequent documentation of that navigation unit to figure out how it works. That might be outside of the scope of Dave's blog, however.

author: bills
author_rank: Frequent Contributor
timestamp: February 25, 2016, 02:40:33 am
content: Quote from: Kjetil on February 24, 2016, 03:27:54 pmWOW !That is amazing, to build that type of machine with the tool's they had at hand I am in awe.bill

author: Tothwolf
author_rank: Regular Contributor
timestamp: February 25, 2016, 04:10:43 am
content: Quote from: EEVblog on February 24, 2016, 10:34:10 pmThe upper housing appears to be made of cast aluminum (which is why it broke when impacted). It actually is possible to solder to aluminum with tin/lead alloy solder but you have to use a very active flux to cut through the aluminum oxide so the solder can wet. If it wasn't soldered, it might have been brazed using a zinc alloy filler.The round connectors are most likely some type of Bendix connector. The contacts and the crimp tool are readily available if you can find the correct housings.

author: AF6LJ
author_rank: Unknown
timestamp: February 25, 2016, 04:28:05 am
content: This was Really Good Thanks Dave

author: Fungus
author_rank: Super Contributor
timestamp: February 25, 2016, 09:16:00 am
content: Quote from: EEVblog on February 24, 2016, 10:34:10 pmPlenty of WWII warplanes were made of Magnesium. It's notthateasy to ignite.(maybe they were desperate times and the other advantages of Magnesium outweighed the fact that it could burn)

author: PinheadBE
author_rank: Regular Contributor
timestamp: February 25, 2016, 11:31:02 am
content: Now, THAT thing is a BEAUUUUUUTY !I don't like it, I love it!

author: Smalltalk-80
author_rank: Newbie
timestamp: February 25, 2016, 10:29:49 pm
content: Quote from: HAL-42b on February 24, 2016, 11:58:56 amThe above speculation is not very well thought through or researched.The Nike program of missiles in the 50's used analog computers of varying complexity in the same role as the D-17B. I only used it as an example because it was contemporary with the introduction of the M1.The Apollo program had no use for something like the D-17B. It was a pretty crude and simple piece of electronics by the standard of the day that was primarily made for relative ease of manufacture and very high reliability, versus ease of use, speed, flexibility and precision.Not using the best technology for the fear of it falling into the hands of the enemy is also doubtfull in this case. Transistorized analog computers where not bleeding edge tech in the mid 60's and the soviets had equivalents.And you'd never hold back on using something that would give you a very real and tangible advantage in battle for the fear of it revealing secrets, even though it is a very real risk as witnessed with the Lorentz cipher in WW2.

author: wkb
author_rank: Super Contributor
timestamp: February 25, 2016, 10:38:37 pm
content: Quote from: Fungus on February 25, 2016, 09:16:00 amIt could be an alloy called Electron. Used in racing bikes for reasons of weight en strength.

author: janoc
author_rank: Super Contributor
timestamp: February 25, 2016, 10:52:07 pm
content: Magnesium doesn't ignite just like that. Powdered magnesium or thin strips of it yes but a metal sheet no. It is not that much different from aluminium - that also burns really well when powdered but doesn't quite ignite normally.

author: mikerj
author_rank: Super Contributor
timestamp: February 26, 2016, 11:03:46 am
content: Quote from: HAL-42b on February 24, 2016, 11:50:14 pmAluminium solders are readily available e.g. Multicore Alusol.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: February 26, 2016, 08:37:09 pm
content: BTW: the black cylindrical object that Dave could not identify at 22:00 looks to be a military style relay. The coil voltage would be 26.5V and the contacts were rated for 5A. The many connections on the bottom indicate that it may be 4PDT. Many of them, then, had quite a few contacts and the military would have sealed them against the atmosphere to protect the contacts. I have a few just like it.

author: jh15
author_rank: Frequent Contributor
timestamp: February 27, 2016, 01:45:51 am
content: I'll send you a length of tape (adhesive backed, by the way to get started).I also have a sacrificial device i can un hermetically seal, and somewhere a bigg ass souldering iron. This may be my first Youtube:look for it: Opening mil-spec hermetically sealed device or the like. Just a powerline monitor D'arsonval expaned meter in a can.This is fun, I will learn youtube, links to dave, Fran, electric stuff, all those in our bubble. google plus links, twitter, etc.Maybe you guys can look at previews before I publish it.I miss Fran and Jeri Ellsworth new stuff, being forced to have commercials I guess.P.S. I spin up my rocket gyro or whatever it is from a Phase Linear 400 audio amp at 400cps. Fine for syncros too.I can drive blocks with it spinnig and still have it precess on a friends table from inertia.i used to be an audiophile, but not a phool, fun to watch those people.

author: ErikI
author_rank: Newbie
timestamp: February 28, 2016, 11:03:26 am
content: Could not resist.

author: ShiftRegister
author_rank: Newbie
timestamp: February 28, 2016, 10:20:50 pm
content: Now this was pretty cool review. Hats off to whoever send this to Dave for tear down.

author: broz
author_rank: Regular Contributor
timestamp: March 02, 2016, 10:55:20 pm
content: Quote from: rrinker on February 24, 2016, 03:44:24 amI 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!

author: broz
author_rank: Regular Contributor
timestamp: March 02, 2016, 10:58:16 pm
content: Also....wonder if this computer is Turing Complete??

author: mbqwerty
author_rank: Newbie
timestamp: March 03, 2016, 05:24:47 am
content: Quote from: broz on March 02, 2016, 10:55:20 pmThat would be a governor on a steam engine.

author: rrinker
author_rank: Super Contributor
timestamp: March 03, 2016, 01:52:49 pm
content: Quote from: mbqwerty on March 03, 2016, 05:24:47 amRight. 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_governorIn 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.

author: broz
author_rank: Regular Contributor
timestamp: March 03, 2016, 03:25:45 pm
content: Quote from: rrinker on March 03, 2016, 01:52:49 pmRight! My bad, thanks guys

author: SeanB
author_rank: Super Contributor
timestamp: March 03, 2016, 05:01:51 pm
content: 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.

author: chris_leyson
author_rank: Super Contributor
timestamp: March 03, 2016, 07:09:47 pm
content: 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.

author: Kaptein QK
author_rank: Regular Contributor
timestamp: March 04, 2016, 06:40:38 pm
content: Quote from: rrinker on February 24, 2016, 03:44:24 amHaving seen those before I think that is a multi-turn spring with rather constant torque within its operational range.

author: stejep
author_rank: Contributor
timestamp: March 05, 2016, 06:00:24 am
content: 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.

author: jefferyrowan
author_rank: Newbie
timestamp: March 05, 2016, 06:16:56 am
content: Quote from: Smalltalk-80 on February 24, 2016, 09:15:23 amThe 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.

author: Brumby
author_rank: Unknown
timestamp: March 05, 2016, 06:27:31 am
content: 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.

author: jh15
author_rank: Frequent Contributor
timestamp: March 08, 2016, 10:12:04 pm
content: I maintain a community radio station and it is like fixing an airplane while flying... Live DJs 24/7/365.

author: Don Hills
author_rank: Regular Contributor
timestamp: March 09, 2016, 10:32:36 am
content: Quote from: jh15 on March 08, 2016, 10:12:04 pmDead air isn't quite the same as dead dead.

author: SeanB
author_rank: Super Contributor
timestamp: March 10, 2016, 05:34:37 pm
content: Quote from: Brumby on March 05, 2016, 06:27:31 amBeen 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.

author: Brumby
author_rank: Unknown
timestamp: March 11, 2016, 04:01:25 am
content: Did you check the tyre pressures while you were at it?

author: ale500
author_rank: Frequent Contributor
timestamp: March 13, 2016, 10:09:07 am
content: Quote

author: rm31859
author_rank: Newbie
timestamp: February 11, 2018, 08:43:34 pm
content: 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.