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How to open a real sealed Attitude Indicator

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Hi everybody,I just got an Lear Inc. MM1 Attitude Indicator ( former Navy BuAer)I want to open in order to see how I could equip it with RC servos.But it is sealed and there is no screw. Nothing indicating me how to open that beast. Is there anybody with maintenance knowledge???Thanks a lotregardsRoger

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Mike,You always are very helpfull. Very interesting. Thanks. Unfortunately I cant see any email adress of the author.RegardsRoger

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Guest MikePowell

Roger,The email link is hidden behind the word "ask" on this page:http://www.geocities.com/ehud42/software/ Another possibly knowledgeable person is Martin "Pogo" Ingold. He is collecting items for his fighter simpit and has posted a great many pictures on his site, www.f16cockpit.net . One or two of the instruments have been opened to show the mechanisms.Please let me know what you find. I have a defunct VSI I work like to open without further damaging it.Mikewww.mikesflightdeck.com

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Mike,I got some feedbacks on other forums. The Dremel seems to be the only solution for us.I will try that way.RegardsRoger

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Guest MikePowell

Thanks, Roger.Mikewww.mikesflightdeck.com

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So it is now. I think that this Attitude Ind. comes from a simulator.There is no gyro inside, only two stepper motors.It means that may be I can used the genuine motors with a 5Oz -400hz converter ???Knowledged people in that area are welcome. I tried to find out the mail of Matt Wielspach who used original simulator instruments in its F 15 sim. If by chance somebody has it ??ThanksRoger

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Guest MikePowell

Roger,Those are nicely detailed pictures. Thanks for posting them. How much trouble was it to open?It is possible that the unit is flight rated. It could be intended to be used with a remotely mounted gyro. (Speculation on my part.)I do not have Matt W's contact information, however, I believe I read somewhere about Matt W., and Matt Ford working on James Price's 737 sim. If I have remembered correctly, Matt Ford ( www.737sim.com/email for contact info) may be able to help you get in contact with him.Mikewww.mikesflightdeck.comInfo for simpit builders.

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Roger,It is unlikely it is from a simulator. Most ADI's are servo driven. The ADI receives signals from either a vertical gyro or an AHRS (Attitude & Heading Reference System). These signals drive the servo motors within the ADI, to give the relevant pitch/roll information on the ADI display. Nowadays, modern aircraft tend to have AHRS, which replaces the system of vertical and directional gyros.In fact most instrumentation used on commercial and military aircraft are servo driven, be it the ASI, Altimeter, VSI, etc etc. As far as I am aware there is no 400Hz to 50Hz converter. Re Matt Wielspach, he has apparently used components from AHRS and ADCs (Air Data Computers) to create custom circuitry to run his instruments. These components are extremely expensive to buy, as some of the individual Digital to Synchro modules are $1000(US)+ each. I don't think there is an easy or cheap way of converting your ADI. If you do find a way, let us know, as there are quite a few out there looking for a method to drive their ADI's and HSI's. You may want to try Gene Buckle, as he was trying to find a solution to drive the ADI in his F15 sim.Best RegardsDarren

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Guest MikePowell

Roger,After reading Darren's post and doing a little further research, I think it should be possible to make use of the existing motors, which I believe are synchos or something quite similar. I have a rudimentary knowledge of synchros (just enough to make foolish posts on public forums) and don't see why generating the necessary drive voltages should not be possible. The basic syncho transmitter is a rotary transformer with the power applied to the rotor. There are three windings in the stator (or field) surrounding the rotor. The stator windings are physically positioned 120 degrees apart. The synchro receiver is similarly constructed. The receiver stator windings are driven with the voltages produced by the transmitter stator windings. The receiver rotor is powered from the same source as the transmitter rotor. A bit complicated, but the bottom line is that the rotor in the receiver synchro will turn to follow any movements of the transmitter rotor.Before I get too carried away, is there any further information available on your ADI? Your pictures show more wires than are necessary for a "simple" 3 phase synchro. Perhaps it is a 5 phase unit.Mikewww.mikesflightdeck.com

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Thanks Darren and Thanks Mike for your knowledged answers.The motor are in fact driven by 12 inputs which are divided in 4 groups. Input 1 and 2 are separated from input 3, 4, 5 which are separeted from 6 and 7 and the last group is 8,9,10,11,12.Input 1, has also what seems to be an Output as well as 4,5 and 9,10,11,12.With the help of some custommade aluminuim pieces it seems to be possible to get some RC servos in. But if there would be a solution with the real motors, I would prefer.Does anybody know what happend to the Lear-Siegler Company who produced that ADI. The should may be have some schematics, or then some maintenance companies working with the Navy and the USAF.All infos are welcome.Many thanksRoger

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Mike,You can of course use my pictures in your site dedicated to real simulated instruments.RegardsRoger

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Guest MikePowell

Roger,Good morning from California.Synchros do not produce a great deal of torque. It is adequate for small mechanical loads like indicator pointers, but not a whole lot more. (Just where the cutoff is I don't know.) For larger loads the receiver synchro was used as a position sensor by comparing the outputs of its stator windings to those of the transmitter synchro. Differences were used to generate drive voltages for a motor mechanically coupled to the receiver synchro's shaft. The motor would rotate the shaft to zero out the differences. Based on the pictures and your descriptions, I think it likely that this is how your ADI is configured. So the situation is rather more complicated than my original optimistic hopes. Still doable, but requiring more information about the unit than is available.Service documents would be a great help. Even the wiring diagram. I will keep my eyes open for them, but I wouldn't hold up progress on converting the ADI to RC servos. It's likely to be much less expensive as well as quicker.Thank you for the offer to use the pictures.Mikewww.mikesflightdeck.comInfo for simpitbuilders.

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Dear Mike,Good evening from Alsace, France where I am dreaming of California.I used to live in L.A. ( Marina del Rey) in 1988/1989. A french company sent over there to produce a movie. I wanted to stay after the production was completed, but it was not that easy, green card and so on. My last trip was in 1999. I have there some good friends, among them the legendary Hollywood Director, Richard Fleischer ( Boston Strangler, Tora, Tora, Tora, 2O.000 leagues under the sea, Viking and 50 other films).Back to the topic. I think you right and I should go in direction RC servos. Thanks for your help, Mike.RegardsRoger

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