Secret Project revealed - TACAN HSI Instrument for FSX

[Aircraft Aviation 2]

WANT TO SEE this instrument up-close and in real life? Find me at FSC Weston this Saturday; I can be identified by my Mutley's Hangar T-Shirt and, erm, long hair! See you there!

This post is compromised of several sections. If you want to know everything, read from the start. However, if you just want to know certain bits, flick through the underlined and emboldened sections. Please note, there are VIDEOS and SCREENSHOTS at the end of the post, so make sure to read right down to the bottom if you want to see these.

Hi everyone,

As well as working away at the Overhead and Pedestal projects these past few months, I have secretly been working on another project.

A HSI, or horizontal situation indicator, is one of the most important gauges in a cockpit. It allows heading, course, glideslope, VOR and even DME information at a glance; all within one instrument. Over the past few months, we have been working on getting a full-functional HSI for FSX working - with all the bits and bobs you'd expect from such a vital and complex instrument.

History

Almost 1 year ago, after visiting "CockpitFest" in Newark, my father and I purchased an ex-BAE Hawk trainer instrument for £25.

It was a TACAN HSI instrument. For that price, we expected it to be a non-functioning part, or an unusable or outdated piece of technology. But boy, how wrong we were...

It turns out we had unlocked a treasure trove of possibilities. Our £25 investment had turned out to be a fully-functioning HSI instrument worth well over £4500. Amazed, we immediately looked at how we could get it working with Flight Simulator X.

Unfortunately, some of the original circuitry was non-compatible with anything we'd ever want to use, and as a result, we have removed it (but not discarded it!). Luckily, all the original gearing, motors and other circuitry is exactly how we'd want it to be.

A few months after obtaining the instrument, I was offered a hardware review by Spanish hardware manufacturer, Opencockpits. It was definitely a "Eureka" moment; what better to chance to obtain a product that would power our newly-purchased HSI.

So, I snapped up the opportunity to get an Opencockpits DC Motors Card (review by myself here: http://www.mutleyshangar.com/reviews/jack/dcm/dcm.htm). I would have also purchased a master card, to power some of the outputs, however I already have one, so I thought I'd save a bit and just use the one I already have.

In terms of getting the instrument working, it was an easy but very time-consuming process. All we had to do was wire all of motors and outputs to their respective cards. And then put protective components in. And then obtain a pulse counter-mechanism (see later). And then do the SIOC scripting. And the-...

You get the point. It took a very long time. Luckily for us though, we didn't have to do much "hands-on" work; the company that manufactured the part, SimTech, had done ALL of the gearing and connections for us (well, BAE actually).

Technological overview

It immediately became apparent how fragile an-instrument this was. There are so many gears and intricate clockwork-style mechanisms in the instrument that just the slightest knock could destroy it. Please enjoy sampling the internal circuitry of the instrument:

As you can see, the instrument is a masterpiece of technology. Things to note in the above pictures are...

Motors. There are a whole range of DC motors in the instrument, however, luckily, they are all of the same type. This means that they're all compatible with the Opencockpits DC Motors Card. Through SIOC scripting, I can control all motors in the instrument, the functionality of which is explained later.

Potentiometers. These variables resistors provide "feedback" - a signal for the SIOC software to reference all its positions to. These adjust their resistance whenever their respective motors turn (they are on the same shaft as the motors).

Other wires. There are so many wires, it will take months for me to explain, in detail, every one. Just have a look at where they go and you might understand it. In the top left of the instrument, just behind the "RANGE" counter, there is a display pulse circuit which counts (numerically) up. See later for more information.

Functionality Overview

All functions are referenced to the above photograph...

Flags - OFF Flag, RANGE Flag, G/S Flag, "White Triangle" and NAV Flags are ALL fully-functional and modeled.

Course Pointer - The yellow pointer is driven by one of the aforementioned DC motors (see above and pictures). Also, the analogue-digit display visible in the top right of the instrument directly mimics the position of the pointer (ie if the course pointer is pointing at 175, the digits show "175").

VOR Deviation Bar - The horizontal yellow bar visible in the middle. Likewise, this is driven by a DC motor, and moves left/right/centre depending on the location of the VOR tuned in the NAV1 frequency.

Glideslope Indicator - On the left side of the instrument, this yellow needle moves up and down depending on the position of the aircraft from the tuned ILS beacon frequency. If the needle is perfectly in the middle, you're bang on the glideslope. Driven by a DC motor.

Green and White Bugs - These bugs are driven by a motor(s), and can display any heading you want them to (perhaps for heading reference or for part of your navigational plan). They also have reciprocal "tails" 180 degrees from their heads.

Heading Bug - This yellow bug, which revolves around the outside of the heading scale, represents the autopilot selected heading. The move, the bug, you must use the "HDG" Knob.

HDG and CRS Knobs - The CRS knob adjusts the yellow course pointer. A rotary encoder is attatched to the CRS knob, which sends a signal to SIOC, then feeds the signal back to the DC motor driving the course pointer. The HDG knob, as previously mentioned, controls the heading bug. Both the CRS and HDG knob feature precision engineered grooves, as in real life. They also feature a true "Lock and Lift" mechanism; which means to work them, you must pull the Knob OUT then move it, then release it for it to go back in.

4-Digit RANGE Counter - This neat piece of kit uses a pulse counter to represent the distance from your VOR tuned in the NAV1 frequency. Its function is explained in detail below.

Pulse Counter Circuit

The RANGE display in the upper left corner is shielded by a flag. However, when a DME/VOR signal is available, this flag retracts and a 4 digit display is visible.

A pulse circuit, initiated through SIOC, powers this display. Each pulse (OFF-ON-OFF) adds "1" to the display. It goes all the way to 9999 before resetting to zero. However, what are the chances you'll be that far away from your desired VOR station. Very slim!!!

There is also a "reset" pin, which simply pops the counter back to 0000. Also, there is a "select" pin which chooses if I want to count UP or DOWN. EG:

To count from 0 to 43...

- I ensure that the 5V power supply is plugged in

- I make sure that the "select" pin is on UP

- I give the instrument precisely 43 pulses, controlled by SIOC

- Finally, I engage the reset pin if I want to reset the display back to 0000

NAV and "White Triangle" Flags

Whilst these flags do operate using a standard 5V output, they are special, and deserve their own section.

It is important to mention that these particular flags are GRAVITY OPERATED. This means that, even if the outputs are activated, the flags won't necessarily move unless the course pointer is in a specific position.

The White Triangle flag has three positions. "OFF" is when the flag is invisible (ie tucked behind the instrument); "ON LEFT" is when the flag pops up into the LEFT triangle slot; and "ON RIGHT" is when the triangle is visible in the right triangle window.

In terms of explanation, that's about it! If you want to know how to operate a HSI generally (ie you've never used/seen one before), then I suggest you Google "HSI instrument" or check out Wikipedia.

Oh, I almost forgot. What's a good post without beautiful screenshots! Enjoy! :icon_thumbup:

"Wait! Those screenshots just show pictures of the instrument in a stationary position. I want to see it WORKING!"

Absolutely no problem! I spent many, many hours shooting the following video clips which fully detail the HSI's operation and technical components. I would like to say a HUGE, MASSIVE thanks to Joe Lawford for taking the time and effort to upload these for me; due to my appalling upload speeds.

There are two videos, split up into parts...

HSI Operation (watch this first)

Part 1

Part 2

Part 3

Part 4

Part 5:

HSI Gearing and technological information (watch this second)

Part 1

Part 2

Part 3

That's all! Thanks everybody; I really hope you've enjoyed this insight into the "secret project".

As always, comments/criticisms are welcome.

Kindest regards,

Jack :001_th_smiles89:

[needles 1,013]

FANTASTIC Jack!

Well done to you and your father and what a bargain you got.

It really is a work of engineering art.

I'm so envious.

Can't wait to have a chat with you at Weston.

Stunning vid's and write-up well done again.

[mutley 4,498]

All I can say Jack is that is a fantastic instrument worth 10 times what you paid for it.

I am really loving your video documentaries.

First Class!

[Aircraft Aviation 2]

Thanks so much Brian and Joe! It is indeed a work of art, I apologize but I cannot be anything put un-modest on the project, I have loved it so much!

I'm so glad you enjoyed the video blogs Joe, and, please be honest, how did you find the blurriness this time round? And the photos, of course.

Indeed, we shall have a good chat at Weston. In fact, speaking of that, you may have heard me mention that due to the project's size, it may be coming with me... Along with something else very special :001_th_smiles89: .

I'm in the chat if anyone wants a word!

Jack

[mutley 4,498]

Jack,

The photos and the video footage is excellent, I found it difficult to view the last series of videos as my eyesight is poor so catching up with the next view and focussing was a chore and took away from the enjoyment.

With this new series I found it easy to follow and appreciated the raw video footage because it was much easier to view and absorb.

But that's just me, half blind, deaf and stupid! Old age is not what it is cracked up to be!!

A really captivating post Jack. :icon_rockon:

[Aircraft Aviation 2]

Hi Joe,

Thanks for the excellent feedback. I'm really glad you enjoyed it.

Jack,

The photos and the video footage is excellent, I found it difficult to view the last series of videos as my eyesight is poor so catching up with the next view and focussing was a chore and took away from the enjoyment.

Glad you found the footage/pictures great! It took awhile, but it was worth it! If you notice, I actually usd a Tripod for 90% of the videos and screenshots, so that's why they are MUCH better resolution than some of my previous videos.

Blurriness is to be expected in the last video; as I said I moved it off the Tripod so I could reach round the back, and my camer isn't the best for motion blurr as you know!

With this new series I found it easy to follow and appreciated the raw video footage because it was much easier to view and absorb.

Fantastic! It is really difficult to communicate certain points when talking about cockpit building, so I'm chuffed that you found it educational as well as enjoyable. I think it's great that you like the new video style, as I thought that it would provide a much better insight into the way we do things, and clearly, it has!

I must admit that the "live" (or, as you put it, raw) nature of the video makes it easier to understand things, maybe I should do this agan in the future.

But that's just me, half blind, deaf and stupid! Old age is not what it is cracked up to be!!

A dab-hand at the Pinball table!!! :biggrin:

Kindest regards,

Jack

[Aircraft Aviation 2]

Hi Joe,

Thanks for the instructions; All is done!

Jack :001_th_smiles89:

[hurricanemk1c 195]

I am amazing Jack - superb work there and a stunning masterpiece!

[Aircraft Aviation 2]

I am amazing Jack - superb work there and a stunning masterpiece!

Thanks very much Kieran; glad you found it interesting!

[stu7708 244]

That was some impressive stuff.. and a perfect example for me on a practical use for the DC motors card

Like Joe said the quality of the photos and video are very good, just one or two of the photos that was a bit off focus.

Looking forward to seeing this used together with FSX...

Oh, and as a little side note, that might cause some trouble in your scripts, I actually think the range meter runs up to 999.9 miles and not 9999. At least that's how I read it considering the big white dot after "RANGE" on the instrument. Still more than enough range for VOR:s but that makes less over the top...

Just one small question. Can you in a easy way start the range counter at a specific digit and start counting down from there. As you probably figured out I'm thinking of how to reproduce the moment when the Nav radios pick up a VOR signal, and you start to fly towards it.

[Aircraft Aviation 2]

That was some impressive stuff.. and a perfect example for me on a practical use for the DC motors card

Like Joe said the quality of the photos and video are very good, just one or two of the photos that was a bit off focus.

Looking forward to seeing this used together with FSX...

Oh, and as a little side note, that might cause some trouble in your scripts, I actually think the range meter runs up to 999.9 miles and not 9999. At least that's how I read it considering the big white dot after "RANGE" on the instrument. Still more than enough range for VOR:s but that makes less over the top...

Just one small question. Can you in a easy way start the range counter at a specific digit and start counting down from there. As you probably figured out I'm thinking of how to reproduce the moment when the Nav radios pick up a VOR signal, and you start to fly towards it.

Stu... Thanks so much; that is a FANTASTIC post!

One thing for sure; I certainly did not realise that the "." above the RANGE was a decimal point. In fact, I had dismissed it as some sort of faceplate printing feature or soemthing like that. You idea makes perfect sense; in fact I'm 100% sure you're right!

Once again; a brilliant comment on the VOR signal display. I myself have been thinking about exactly what you wrote for a very long time(ie what's the best way to script it, and so forth).

Basically, the value of the VOR1 DME radio is supplied by FSUIPC. For some reason, this value is multiplied by 10, so in my SIOC program I have to divide it by 10 to get the real value. EG:

- I'm 55 Nautical Miles from Station X

- FSUIPC says I'm 550 Nautical Miles from Statio X

- I divide this value by 10

- SIOC now thinks I'm 55 Nautical Miles away; which is correct

Then, using this "correct" value, I can begin to send the signal to the display. As I mentioned in the videos and write-up, this display isn't normal in the sense it doesn't use a graphical signal from a PC; it uses "pulses". EG, to get from 0 to 1 Nautical Mile...

- Display reads "0"

- I give it a pulse (OFF/ON/OFF)

- Display reads "1"

Now, if you can see where I'm going, I can replicate this procedure to get my VOR1 DME distance. EG, if VOR1 = 47 Miles...

- Display reads "0"

- I send it 47 pulses (OFF/ON/OFF/ON/OFF/ON/OFF/ON/OFF......)

- Display reads "47"

Now, your comment was regarding how to count DOWN. There is a special "selector pin" in the display circuit which does just this. The exact same procedures are followed for counting up as well as counting down, all that's different is the voltage across this "selector pin". EG:

"My VOR1 DME display reads "0" (AKA: I don't have a frequency tuned). I then tune a frequency, my VOR1 DME reads "17". I then approach this station; it counts down"

This is what I'd do:

- Display reads "0"

- Ensure selector pin is on 5V

- Give it 17 pulses... The instrument reads "17"

- Ensure selector pin is on 0V

- Give it X pulses (where X is whenver it drops by a mile)

- Instrument counts down until it reads "0"

And that's basically it. However... It isn't as simple in SIOC. I can't simply tell it to do that and expect it to perform exactly how I say. It is much easier for SIOC if all pulses are taken from "0"; IE, if we're at 17 miles and drop to 14 miles, we do this:

0 -> 17 RESET "0"

0 -> 16 RESET "0"

0 -> 15 RESET "0"

0 -> 14 RESET "0"... And so on...

I tell SIOC to do this so fast, that the human eye barely notices. Otherwise, it would be weird to see a VOR1 DME display going to "0" ever second or so.

I hope that you understood all that; no problem if you didn't! Although, by the skill you showed in your last post, you have nothing to fear :icon_thumbup: .

Jack

[stu7708 244]

Stu... Thanks so much; that is a FANTASTIC post!

One thing for sure; I certainly did not realise that the "." above the RANGE was a decimal point. In fact, I had dismissed it as some sort of faceplate printing feature or soemthing like that. You idea makes perfect sense; in fact I'm 100% sure you're right!

Well then, you're more than :icon_welcomeani: . Glad I could help out in some small way.

Once again; a brilliant comment on the VOR signal display. I myself have been thinking about exactly what you wrote for a very long time(ie what's the best way to script it, and so forth).

Basically, the value of the VOR1 DME radio is supplied by FSUIPC. For some reason, this value is multiplied by 10, so in my SIOC program I have to divide it by 10 to get the real value. EG:

- I'm 55 Nautical Miles from Station X

- FSUIPC says I'm 550 Nautical Miles from Statio X

- I divide this value by 10

- SIOC now thinks I'm 55 Nautical Miles away; which is correct

Hmm.. just a thought. It could be that FSUIPC includes the decimal value of 0, but for some reason prefers to use an Integer variable instead of a Floating variabel and due to that multipies by 10... and come to think of it, considering the decimal point on the instrument it's 550 you want to insert into SIOC, right?

Then, using this "correct" value, I can begin to send the signal to the display. As I mentioned in the videos and write-up, this display isn't normal in the sense it doesn't use a graphical signal from a PC; it uses "pulses". EG, to get from 0 to 1 Nautical Mile...

- Display reads "0"

- I give it a pulse (OFF/ON/OFF)

- Display reads "1"

Now, if you can see where I'm going, I can replicate this procedure to get my VOR1 DME distance. EG, if VOR1 = 47 Miles...

- Display reads "0"

- I send it 47 pulses (OFF/ON/OFF/ON/OFF/ON/OFF/ON/OFF......)

- Display reads "47"

Now, your comment was regarding how to count DOWN. There is a special "selector pin" in the display circuit which does just this. The exact same procedures are followed for counting up as well as counting down, all that's different is the voltage across this "selector pin". EG:

"My VOR1 DME display reads "0" (AKA: I don't have a frequency tuned). I then tune a frequency, my VOR1 DME reads "17". I then approach this station; it counts down"

This is what I'd do:

- Display reads "0"

- Ensure selector pin is on 5V

- Give it 17 pulses... The instrument reads "17"

- Ensure selector pin is on 0V

- Give it X pulses (where X is whenver it drops by a mile)

- Instrument counts down until it reads "0"

And that's basically it. However... It isn't as simple in SIOC. I can't simply tell it to do that and expect it to perform exactly how I say. It is much easier for SIOC if all pulses are taken from "0"; IE, if we're at 17 miles and drop to 14 miles, we do this:

0 -> 17 RESET "0"

0 -> 16 RESET "0"

0 -> 15 RESET "0"

0 -> 14 RESET "0"... And so on...

I tell SIOC to do this so fast, that the human eye barely notices. Otherwise, it would be weird to see a VOR1 DME display going to "0" ever second or so.

I hope that you understood all that; no problem if you didn't! Although, by the skill you showed in your last post, you have nothing to fear :icon_thumbup: .

Jack

Well, I think I grasped the fundamental parts of it but it feels like there should be "neater" way of doing the count up/down part. I'm, as you no doubt already picked up on not familiar with the scripting language used for SIOC, but I have hacked a few lines of VB script in my day.

I guess you have some sort of trigger waiting for the value in FSUIPC to change in place already, and I seem to recall from one of your previous reviews that it's a fairly simple procedure to declare variables. If the values of your declared variables remains in memory once the range meter has been set I'd do something like this in a VB script.

Declare three variables, "CurrentDistance", "NewDistance" and "Difference" as Integer

Once the trigger picks up a new value from FSUIPC set NewDistance to the FSUIPC value. Then set Difference = NewDistance - CurrentDistance

Then using an IF statement, check if difference is greater than 0 and set your outputs to the instrument to increase the value if TRUE and decrese the value if FALSE

Then send "Difference" pulses to change the range meter, and finish up by setting CurrentDistance = NewDistance

Hope that made sence, and that it's possible to implement in the SIOC scripting language...

[Aircraft Aviation 2]

Hi Stu,

That really does sound like a great logic; ie just sending the pulses you need, not "refreshing" them every few seconds.

I think, for the most part, that is achieveable in SIOC, however there is one problem.

How does SIOC tell the difference between the "Current Distance" and "New Distance"? There is only one input source to SIOC regarding the VOR1 DME value, and this is always the "live", current distance you are from the station.

In other words, I don't think we can tell SIOC to "remember" the last distance, in order to subtract the new value and add/subtract the difference.

Please tell me what you think.

Regards,

Jack :001_th_smiles89:

[stu7708 244]

Well, you are the resident expert on SIOC here but it does sound strange that you can't declare a variable for computations that's independent of the input source.

Looking back at your Seven Digit Display Card review I found some code for declaration of variables.

I.E.

“Var 2, name SPD_DP, Link IOCARD_DISPLAY, Digit 1 Numbers 5”

Is there no way to omit the Link part of that declaration in SIOC, and thus having a global variable available for storing the CurrentDistance value in?

[Aircraft Aviation 2]

Well, you are the resident expert on SIOC here but it does sound strange that you can't declare a variable for computations that's independent of the input source.

Looking back at your Seven Digit Display Card review I found some code for declaration of variables.

I.E.

“Var 2, name SPD_DP, Link IOCARD_DISPLAY, Digit 1 Numbers 5”

Is there no way to omit the Link part of that declaration in SIOC, and thus having a global variable available for storing the CurrentDistance value in?

Oh Yes of course, you can declare "non-linked" variables eg:

Var 9000

Is accepted, just Var 9000 on its own. However, my concern is the value that the holding variable will actually hold.

Jack

[stu7708 244]

Well, since it's not connected to an input of any sort why should it hold any other value than what you program it to hold in your scritps?

Ending the function used to manipulate the range meter with

&CurrentDistance = &NewDistance

where NewDistance is a variable linked to the FSUIPC output for the VOR range meter in FSX should do just that...

There should be no harm in testing it out I think. If SIOC resets the CurrentDistance variable to NULL once the commands are executed the rest of the script will do exactly what you're already doing, but without the reseting of the range meter first, so it should be rather obvious with in a short period of time if it's working or not.

[Aircraft Aviation 2]

Hi Stu,

Please may you state the values of both variables ("current" and "new") in the following scenario:

- VOR1 inactive; shows 0000/9999

- Then, VOR1 tuned to an appropriate frequency. It states 55nm away

- I fly 13 miles to my target, leaving 42nm. Please can you state what each variable value is at these times?

Jack

[stu7708 244]

It all depends on what the command that runs every time the linked value to FSUIPC changes, assuming that is what triggers the execution of the command.

I've got a full day ahead of me at work today, but I'll try to write up a detailed description of it based on my VB script example above and get back to you tonight or sometime during the weekend.

[allardjd 1,853]

Good stuff, Jack. That kind of stuff is just plain fun. If designed today, it wouldn't be done that way, of course and most of the mechanics of what you have would be done electronically and displayed digitally by various means. That one is an interesting blend of technologies, e.g. the digital output (LEDs or Nixie?) in the range display is a generation ahead of most of the rest of it. In a way, that box has a foot in two different eras. The tape in the course window is at least a generation older, but whoever designed this saw fit to use both methods. It would be interesting to know the reasons. Space? Cost? Visibility? Power usage?

 

One is a driven value provided by the circuitry and the other is a manual setting - maybe that played into it. We'll never know, but someone, somewhere decided to use the digital dispaly for range and the tape for course. I find that kind of thing really interesting.

 

The ability to interface physical instruments of that age to flight sim opens the door for cockpit builders to tap the market for spare, surplus and salvage instruments from RW aviation technology. There is a lot of that stuff around that either has little demand or that can no longer be certified for flight (e.g. the "For Ground Use Only" tag on yours). Instead of being obsolescent and useless junk it can now be put to use by those who love to tweak and tinker and fly the virtual skies.

 

Thanks for sharing.

 

John

[stu7708 244]

Hi Jack.

I have failed to make the presentation of the script in a readable way on the forum.

Have you got access to MS excel at home or at school? In that case I could mail you an excel-sheet with details on the script, where you also can simulate the changes from FSX into SICO via FSUIPC and see how the variables changes.

If that's ok with you, PM me your email and I'll send it over as soon as I can.

[Aircraft Aviation 2]

Good stuff, Jack. That kind of stuff is just plain fun. If designed today, it wouldn't be done that way, of course and most of the mechanics of what you have would be done electronically and displayed digitally by various means. That one is an interesting blend of technologies, e.g. the digital output (LEDs or Nixie?) in the range display is a generation ahead of most of the rest of it. In a way, that box has a foot in two different eras. The tape in the course window is at least a generation older, but whoever designed this saw fit to use both methods. It would be interesting to know the reasons. Space? Cost? Visibility? Power usage? One is a driven value provided by the circuitry and the other is a manual setting - maybe that played into it. We'll never know, but someone, somewhere decided to use the digital dispaly for range and the tape for course. I find that kind of thing really interesting.

The ability to interface physical instruments of that age to flight sim opens the door for cockpit builders to tap the market for spare, surplus and salvage instruments from RW aviation technology. There is a lot of that stuff around that either has little demand or that can no longer be certified for flight (e.g. the "For Ground Use Only" tag on yours). Instead of being obsolescent and useless junk it can now be put to use by those who love to tweak and tinker and fly the virtual skies.

Thanks for sharing.

John

Hi John,

Thanks so much for your detailed reply; and I'm so sorry for my late one.

The instrument is indeed a mix of the generations; incorporating a digital display with an analogue gauge. Personally, I love the combination!

I think I can perhaps explain why the course tape is analogue. It runs directly off the motor for the course POINTER, therefore meaning that the two exactly match. If it was part of a seperate circuit, this introduces the possibility for error (not matter how small).

I have thought to myself about the "Ground use only" Tag. Surely, being a simulator instrument, it is never likely to see the air anyway?

Hi Jack.

I have failed to make the presentation of the script in a readable way on the forum.

Have you got access to MS excel at home or at school? In that case I could mail you an excel-sheet with details on the script, where you also can simulate the changes from FSX into SICO via FSUIPC and see how the variables changes.

If that's ok with you, PM me your email and I'll send it over as soon as I can.

Stu, there is a CODE command in the forum, eg:

 This is a code example [/CODE]

Of course, I shall PM you my address too. Thanks so much for all your hard work.

Regards,

Jack

[allardjd 1,853]

Quote

I have thought to myself about the "Ground use only" Tag. Surely, being a simulator instrument, it is never likely to see the air anyway?

 

Jack,

 

If it is the same as a component used in AC and is somehow not certified (failed QC/QA testing, won't calibrate, damaged, repaired with uncertified parts, out of spec somehow) I believe it is required to tag it as not for flight, in case someday someone desparately needs one and says, "Here's one, let's use it.". I think the tagging is a backup to the lack of paper pedigree, or a paper trail that indicates it is not certified for flight.

 

In the case of your specific instrument, it was either never certified, or lost it's certification somehow during its life. The tagging is intended to help assure it is never installed in a real AC.

 

I'm not up to speed on the details of how certified aviation components are tracked, but it's probably similar to what is done in nuclear for safety-related components. If the paper isn't kosher, then neither is the hardware.

 

John

[Aircraft Aviation 2]

Hi John,

When you say "certified", what do you mean? Certified by use with an airline or approved simulator, or certified for use in the air?

My instrument was never, ever meant to see the air anyway, not now or ever, because it has always been a simulator instrument. In a way, it's like stamping an instrument from SimKits "for ground use only", but this is obvious, as they are simulator parts.

Jack

[allardjd 1,853]

I meant certified for flight.

 

Maybe I've got it wrong but it's my impression that the gauge you have is exactly the same as is used in the RW Hawk, not purpose built for use in a simulator (yours or theirs). I thought it was an actual aircraft instrument, which was being used in a simulator by dummying up the inputs to it. If your HSI is purpose-built as a simulator device and is somehow different from the actual Hawk TACAN/HSI, then I've got it wrong, but if that were the case, the "Ground Use Only" label makes no sense.

 

In pressure operated instruments (airspeed, VVI, altimeter) and gyro instruments (DG, attitude indicator, turn and bank), the actual device used in the AC might not be suitable for simulator use, though the pressure ones could be, I suppose if you wanted to fool around with pneumatics. For them it makes more sense to have a purpose built "phony" for the simulator, looking the same from the face, but with electric motors (steppers or selsyns or servo-motors) or a D'Arsonval movement driving the instrument indications for simulator use. In the case of this HSI, I can see no reason why it wouldn't be the exact device used in the aircraft. All the inputs are electrical, except the heading and course settings, which are via knobs by the pilot. The actual AC instrument would serve nicely in simulator use without requiring the separate design and manufacture of a dedicated simulator device.

 

John

[stu7708 244]

Hi Jack.

The problem was more of an estetic kind than how to insert the code. I couldn't find a good way to add my comments in a readable way within the code. Also, the excel-file gives you a better way to manipulate the values and see how the variables changes within the command.

It should be in your inbox by now, so take a look and get back to me if there's any questions.