F.A.Q.’s

F.A.Q.’s (In no particular order and sorry, they seem to grow over time)

Q… Does the motion come from reading the joystick inputs ?

A… No it comes out of the program, it is read from the attitude indicator (the artificial horizon) while you are flying. What you see on the screen is interpretated into motion, where-as, reading the joystick wont give the correct action most of the time.

Q… With your setup, can you program in turbulence ?

A… Yes you could but there is no need to. The platform motion is derived from the artificial horizon instrument, and as the plane goes thru the turbulence, the artificial horizon moves and this is sent to the drive units so you get mostly the same motion as the turbulence on the screen. … Its great … but setting FS on high turbulence can be quite exhausting after a while.

Q… I cant read your wiring diagrams.

A… These are drawn in the electrical industries format of “single line diagrams” where they follow a wire from the start of the circuit thru to the return path, where-as electronic diagrams, tend to indicate IC’s etc and then the wiring between them.

To give an example,, on the relay box diagram, it shows the limiting micro-switch’s that aren’t in the relay box at all… they are on the cam on the output of the steering box.

A great old fella and fellow motion builder, Erich, has really done us all a favor and redrawn my diagrams in a sense that we can all read them !

Thanks heaps Erich… well done. The pages with the diagrams have all been updated with Erich’s diagrams, also the downloadable diagrams are all his work.

Q… I have been told that balance of the platform fully loaded (including pilot) is extremely important. Even small motors can then be effectively used, Can you please comment on this?

A… Well, yes and no… I have estimated on mine, the “out of balance” is plus and minus 50kg so that gives a 100kg range. It performs the same if Liz or myself is in it and believe me, I’m big and she is small. You do notice a difference in its speeds etc if no-one is in it.

All in all… it depends on your motor torque and gearing. … “Back force” also has a factor in this. (See next 2 questions)

In essence, I shoved everything I could up the front. Power supplys, computers etc. Never actually weighed anything.

Q… What types of wiper motors are they ?

A… The type I used are off older Jap cars, Datsun I think, but it doesn’t matter… They need to be….

1/.. Able to be electrically isolated from their own body. (Most Jap ones are)

2/.. Rotate on their output shaft in a complete circle at about 50 to 70 RPM (most do about 60 RPM)

3/.. Have a worm drive in them to stop them being forced backwards. Modern ones have only gears in them and are able to be forced backwards… you don’t want this… You can tell the difference by the look of the gearbox on them. Worm drive ones have a rather round “1 big gear look” where-as the gear drive ones have a smaller “bumps going over a series of wee cogs” look and can relatively easily force backwards. (Cute descriptions aren’t they ??)

Q… The steering box’s ? Is there anything special about them ? and what about rack and pinion types?

A… No, nothing super special about them. Just old ones from older 6 cylinder cars. The type required had to be…

As higher rev input as possible (to gear it down) and also to eliminate as much as possible the “back-force” (Where it can be forced backwards with the weight in the sim, while the motors were not powered up.) This “back-force” is a huge problem with rack and pinion types so they were ruled out.

Be easily mounted. (Some are not suitable for mounting on flat steel.)

Have a long output arm off them. (To get the swing. Hence more travel) Mine had a 6 inch center to center distance.

On mine the arm swung thru about 90 degrees and it took 6 turns of the steering wheel to do that, so hence it’s a 24:1 ratio.

Q… Steering box’s seems an odd way to go about it. What about car jacks ?

A… A steering box has the huge plus in that its output is on an arm. The advantage is that when its at center, the arm is horizontal, so a small input is seen by the sim as a good movement and is felt quickly. At the other extreme, when the arm is near the bottom (or the top) a small movement is really noticed as well. To explain this a bit better… when its level, it will take (say) 2 deg of platform movement to feel the difference but if you are already leaning back 6 deg, then another 1 deg feels a hell of a lot. So in short, when you are level, you need deg’s of angle fast, but if you are already leaning back (or forward or sideways) an extra 1 deg feels like a hell of a lot.

Anyway, … Car jacks, the scissor type have a difference in, revs in to distance traveled at the top versus the bottom. A problem to overcome.

Wind up type are a better possibility but tend to be to low in speed of lift given the input rev of a wiper motor and some are real “lumpy” in their gears which you would feel.

UPDATE …………. June 06

On wrecking the old sim, I came across some markings on the good steering box (the one that does the pitch) .. It is off a HOLDEN (I thought it was ford) but its off a mid sixties HOLDEN. Sorry I couldn’t identify the actual model.

I have 2 of these and there is a No. under the body which you wont see when its still on the car ..

132 743 1332 (or the 1332 could be 1532)

?? 743 1332 (or the 1332 could be 1532)

The Numbers before the 743 are quite different between the 2 so I would assume it is the batch or mould number.

If some-one has access to wrecker data, then maybe it could identify the model.??? .. Can you let me know if you do ?? so I can post it here.

Q… I have a wide choice of motors, both 24 and 12 Volt. What HP would you suggest I use? I want to build a fast shoot 'em up platform. 

A… To be quite honest, I don’t know. I would go for the 12 volt one as you can easily increase the voltage and get more grunt and speed BUT there is a down side to that.. shorter motor life. Of course a 24 volt one may already have more grunt, but to increase the speed needs something like 48 volts and that’s getting a bit steep to play with on junk.

Here probably a good place to put a real true statement…. Throw something together and go from there. YOU WONT GET IT RIGHT THE FIRST TIME. Use it as a learning curve.. in fact you probably wont get it right the second time either… But if you don’t try, you wont succeed. This phase is the fun bit.. Let caution go to the wind. What worked for me, may not work for you and what works for you, may not work for me. Experiment, play, have fun, learn.. it’s a great ‘high’ when things go right.

Q… Why use car steering box’s ? They are expensive to buy.

A… I had a few E’mails on this one and it surprises me to think people were actually going to BUY old steering box’s !!

Here in NZ we can go down to the “car dump” and just grab what you want for free !! (or virtually free) so there was no cost at all, but all that aside I would have presumed that steering box’s could be sourced for very little from mates or scrap yards.

Q… So you used steering box’s for your play thing… what are you to use on the next platform ?

A… Good question.. This thing worked so well I am tempted to just build another “updated” platform, rather than spend the big bucks. If I was to build an “updated” one I think there are only 3 choices … All will be DC motor driven….. (Easy to control with speed and softstart)

In no particular order….

1/… Car steering box’s again, but this time with power assisted units. (electric motor driving the hydraulic pump) Advantages… Cheap, has output arm so no need for different speeds near level compared to already tilted.(see above questions)

2/… Motor gearbox / worm-drive units like the commercially available ones. Advantages… Has output arm so no need for different speeds near level compared to already tilted.(see above questions) but are expensive.

3/… Linear actuators. Advantages… Clean and tidy, but will need good positioning feedback to increase the speed around being level versus, slower when already on a tilt. I had a quick research on these and decided my pockets weren’t deep enough to get ones to my spec.s. Watch out if you go down this road… the cheaper ones have VERY low duty cycles. You need 100% duty cycle or they will cook.

All the above would be quite workable and the final decision would probably depend on cost and / or availability.

UPDATE ……. June 06

The Holden steering box driven by 2 wiper motors performed that well that I am going to use that method in the new sim. I am allowing for an easy change to some other method in case they are not powerful enough. The new sim will be quite a bit larger and heavier than the “box” sim so I will just see how it goes.

Q… What about adding more DOF’s ? (Degree’s of freedom)

A… Had lots of E’mails on this one … Most big simulators have 6 DOF’s but the reality of home building rules this out along with the bank balance and Liz.

My rebuild will definitely have YAW (round and round) as this one action plays real funny things in the brain (middle ear stuff)… Real easy for the total immersion of simulation and of course you could (with some extra feedback) use a real compass as well. Mechanically, relatively easy to do.

There seams to be a big interest from other people in adding HEAVE (up and down) which, while there is a pivot still under the platform, can be mimicked to a certain degree by just pulsing the pitch motor with full voltage (no softstart) for a couple of inch’s up or down. Remember you are sitting more of less above the pitch drive unit anyway.

Of course the next step from using a pivot is to replace the pivot with a spline and have a roll drive unit each side of the platform which would really make heave more true to life … pulsing all three motors.

All in all, I’m putting my efforts into yaw.

Q… I don't have a second computer for the control function. Is it possible to use one computer ?

A… There are other methods to do that (EPIC?) but having a second computer to do the motion control keeps it tidy and versatile.

There are some output boards on the market that could replace the second computer… being…

www.opencockpits.com appear to have a board to do it but I haven’t researched it very much. Not sure if their software will handle macro’s. Anyone else been down this road ??

www.flightdecktechnology.com have a very promising approach and their software does run macro’s.

But remember, the second computer can be used for other stuff too. It could be used as another screen for (say) GPS via Maxivista etc. while its doing the motion bit.

I only have a screen, mouse and keyboard fitted to the motion computer when I’m programming it. In normal simulator use, there is no keyboard, mouse or screen attached to the motion computer.

Q… Do I have to purchase FSUIPC? I understand that Peter Dowson is very generous and accredits all freeware if you ask. A registered version is only required for all payware products.

A… Thanks to Erich who approached Peter Dowson, we now have a free key and an updated chcomm so its all free. Thanks Guys. !!!

Q… The control computer, I have Windows 95, will it work?

A… You can give it a try but I wouldn’t use Win95 on anything to do with com’s

Win 98 should be OK but haven’t used it. I can only say that it works with DOS or in a DOS window in ME.

Q… For spike protection, shouldn’t you have diodes across all the relay coils?

A… Yes. They are actually in what I built but never put them onto the diagram. Erich has redrawn the diagrams and they are on the new diagrams so if you press reload or download the new diagrams, they are there.

Q… Why are you switching the relays (in the relay box) with the negative lead. ?

A… I wired everything to suit possible switching with “open collector” transistors. (No need for the relays on the parallel output card.)

Q… Have you tried using a Fresnel Lens reversed? I am told certain makes give a clearer picture this way.

A.... No I haven’t in my trials. Could be a thing to look at if some-ones going down this road though.

Q… I have come across a freeware software called 'portdriver.zip'

A… Although I have seen it and played with it, I still chose to go with ChComm3.zip Can’t remember why.

Q… I cant find Chcomm3a.zip anywhere.

A… You must not be looking in the right places. It is on www.flightsim.com do a file search for chcomm3a.zip. (don’t forget the “a” or you will get the old one)

Q… Have you got some figures on speeds, angles etc.

A… Yes… Some main ones…

Output revs of wiper motors for Pitch 42 RPM after soft-start unit. (At normal speed)

Output revs of wiper motors for Roll 21 RPM after soft-start unit. (At normal speed)

Time taken for roll to go from one extreme to the other 7 seconds (Normal soft-start speed, including the soft start)

Time taken for pitch to go from one extreme to the other 8 seconds (Normal soft-start speed, including the softstart)

Distance sim box travels with pitch from one extreme to the other 12 inch’s at 35” from pivot.

Distance sim box travels with roll from one extreme to the other 5” at 16” from pivot.

Actual angle of “tilt” from center … plus and minus .. 8 deg for roll, 9 deg for pitch. (Aprox)

The pitch unit linear speed (actually at the gearbox output) equates to about 84 inch’s a minute.

Ratio of gearbox 24:1 (6 turns of the steering wheel gives you a 90 degree swing of the arm)

The length of the arm, center to center is 6 inchs. (The center of each hole)

Note that the speed of the motors are way less than the normal output of 60RPM. This is done quite on purpose with the variable speed unit to suit the “feel” and not as the result of overloading.

They don’t seem much but its heaps for a Cessna or 737. Not enough for a shoot-em-up sort of thing though.

Remember you are only feeling the start of the movement.. See my reasoning for this is in the “control computer interface” page.

Just a wee thought on this….

A simulator does not roll and pitch at the same angle as a plane… it sends motion cues to the body to create the same effect. (Coupled with visual, whether its out the window or with instrumentation)

In a plane at (say) 30 deg roll, inertia (Is that the right word ??) keeps you upright in the seat and the center of gravity is still straight down between your feet. (Your coffee wont spill) Now in a simulator, there is no inertia so a roll of 30 deg would send you hanging on your seatbelts and fighting yourself away from the wall beside you. …Plus you would be covered in coffee. …. A totally unreal sensation.

I am increasing the roll and pitch in the new one to something like 10 & 12 deg. And that is something of an over-kill. The present pitch and roll are more than adequate.

Q… Is your platform any good for a “shoot-em-up” type of sim ???

A… Not really as it stands. With a fighter sim you will need more speed and more roll / pitch but that has the complication of, because it is moving in it’s axe’s fast, you will need to have positional feed-back from the drive units so that it doesn’t “get out of kilter”. I haven’t thought about this very much as its not my thing.

Q… What about G forces ?

A… One of the great advantages of having a separate control computer is that you can program in anything you like.

Once you get all the inputs you need you can manipulate all the outputs anyway you like.

With the same setup (I didn’t do this) is you could input the speed, flaps position, braking etc and move the platform to re-create them.

You could read where the flaps are and “tilt” the platform to give you that “slowing down, hanging in the air” feeling etc etc. I did play with acceleration /climb and I think that is still in the basic program somewhere…. But it was only looking at the horizon, where it should have also been looking at increase in speed and / or rate of climb.

Q… Do you need seat belts??

A… No… not at all… Not with the pitch and roll this thing does… In normal flying, do you need belts in a 737 ?? belts in a Cessna??? No.

But if that seems too tame… I do rolls in a Cessna and the motion coupled with the vision, sends your mind into overdrive.. hell of a kick. .. If not a bit too real.

Q… The springs at the side, why ?

A… When the “box” is sitting up and level, the roll drive has virtually no weight on it at all, but when its leaning over for a roll, there is quite a bit of weight bearing down (or up) on the drive. I put the springs there to even out the load so the motor wouldn’t be under big load to recover from a lean in either direction.

The springs are from an old trampoline. The pitch motor works fine with no “outside” balancing.

Q… I think I’ve got it, but what if it doesn’t work ?

A… As the whole thing is modular, break it down to individual sections.

1/… Get Chcomm3 and FSUIPC going on the flightsim computer. (You will need the “nul modem” cable connected to the flightsim computer to do this)

2/... Hook another computer via the “nul modem” to the flightsim computer and use hyper terminal to see its output.

3/… Run my basic code program and you should see the roll and pitch scrolling up the screen (also some other numbers) when you have got it set right.

4/… Make the parallel output board and test it with a (probably supplied with the kit) program.

5/… Run my basic program, hooked to the flightsim computer and you should see the relays clicking etc to the roll and pitch.

6/… Before connecting to the output card you will have tested all the operations of the relay box and softstart units. (In other word’s, it is going) I used push buttons to mimic the output card before I linked the two together.

7/… Hook up the parallel output card to the relay box, hope for the best, pray, tell the wife your not available for hours, allow 3 hours for the biggest high you’ve had in years

Q… Why build one out of junk? Aren’t you better to put your time into building the finished article ?

A… I thought that too. But if I had done the finished article first, it would have been wrong and the mistakes would have cost heaps. Simple information on the net is virtually non-existent and some-one can only go by gut feeling on some things. Put this another way… how many sites on the net have raw simple information on detail of motion platforms ??? None ! ! ! There are sites that show motion platforms and the cost of, but not of how to do it …. there are sites that are full of “theory only but haven’t done it” well I’ve done it and my research (fun ?) is for everyone’s benefit.

The funny thing about doing it with junk first really showed up in my attitude. It turned a “full on” mission into FUN, FUN, FUN, as what eventuated didn’t really matter but in my case, it worked !!!! Hence the website to pass this information on. There is no fun in buying a controller (or what ever) for $500 and finding out its not what was needed. Motion was my dream and I thought I knew it all… well … this junk thing saved me thousands. I am very glad I done it that way.

Q… How often do you update your site.?

A… Not very often …. Its time I cant spend on my sim !!

Q… I cant click and save your pictures.

A… Yes I got to agree on this one. I use MS Word 2000 to make the web pages and it seems to have its own system of dealing with pictures. I cant work out how to get around that one but I’d like to know. Any ideas anyone.?? Would also like to know how to change the picture name from image 1, image 2 etc to “box on pivot” or “relay box” etc ??? I have how-ever allowed complete page download, so you can still get them that way.

Q… It all seems too complicated and you have missed out smaller detail on how to do this.

A… My website is aimed at the pit builder that has a bit of knowledge in general terms (mechanically and electrically) and has done some thought on motion. He needs to know where he is going (or She) and has thought about it a bit. The info is not seen as a “step by step” instruction for beginners but a posting of “this is what I done” as it may help other ones thinking the same thing.

An old fella once told me “A mans ability to do something is only limited by his willingness to learn”. Such true words. ! ! !

Q… You seem to be the only one to do this so I’m a bit nervous of copying your idea’s.

A… Well let me say very loudly, I’m not the only one to do this with junk. I appear to be the only one to put something on the net. Since I started the website I have had heaps of e’mails and pictures … some of them from guys that have made wonderful machines that perform as motion platforms.

The ingenuity of a lot of these has floored me.

I seemed to have stumbled on to a nitch in the flight sim community that had no-where to go and toss their creations or idea’s etc around. There is also the stigma of “He built that out of junk, so it must be crap”. … Well, nothing could be further from the truth. You don’t need to spend megabucks just to make something move. And of course there are a lot of people that just like fiddling with junk, they find it “challenging” even though they could afford to buy the proper stuff.

In reality, its what you have fun doing and where you want to go that counts. That reminds me, Grandma had an electric wheel chair… Motors, cogs, gearbox’s .. now there’s an idea. ! ! !

Q… I came across your site by accident and I think the bug has bitten. Where do I start ??

A… I found the most informative site on the web is www.fscockpit.com It is brilliant and Herman can really take a bow for getting so much info into one site. If you read everything on that site, you will know more than most simmers. From there you can find heaps of other sites and a wealth of information.

At www.simprojects.nl Roland has put together a lot of info and great details of his trials and success’s with homebrew motion systems. You definitely need to go and have a look at his work.

Unless you are very young, you probably wont live long enough to take in all the info available on (or links from) these sites.

Q… Does it not get hot and claustrophobic in the “box”

A… No, not claustrophobic but it did get very hot. (Computers, me, screens, power supplies etc)

I put 2 computer type fans (4”) and pushed air into the “box”,, end of problem. They have to be cunningly fitted so they didn’t let in any light though.

Q… You seem to be breaching N.Z.s Export of Technology act ?

A… Not really, The act prohibits the export of technology to foreign power military organizations, covert dept’s and taxi drivers. I have a permit to cover everything except the Taxi drivers. I can only hope that no foreign taxi drivers are into cheap motion platforms. !!!

Q… So, how’s Liz these days ?

A… She’s just fine, but she still cant understand why I don’t want pot plants in the cockpit ! ! !

IF I WERE TO BUILD THIS AGAIN ?

Hell yes… I’d do it all again… Been great fun building it. An absolutely fun mission.

Updated Jan 07