[simpits-tech] motion systems for sims

[Marv De Beque]

I would argue that pneumatics are such a bad thing for a sim.  the 
bounce can be compensated by a small computer, but I would argue further 
that you may not even notice it since the real aircraft rides on a 
cushion of air, too.

However, driving the sim's motion based on the movement of the stick is 
a tricky problem.  For one it is unrealistic to lean the sim like a car 
in a turn based on stick movement.  The real aircraft may react in 
attitude by the stick, but the movement is sustained over time.  The net 
G effect keeps the pilot pined down in the seat and not leaning over 
like a race car driver.

I have heard of sims that use that type of motion, but only as an 
initial kick to fool the brain into thinking that the aircraft has taken 
on a change of direction and return to the home position at a slower 
rate so you don't feel the return.  Movement is restricted to about 3 
feet.

I don't think that kind of full range motion is practical in the home 
sim, albeit a smaller amount of motion might be very practical and 
helpful in fooling the brain into thinking you initiated a turn or a 
descent, etc.  Getting large amounts of movement is not very practical, 
particularly if you have a projection screen in front of you.  Ideally, 
the screen and projector should move too, but it would be rough on the 
projector.

However, what would be desirable is simulation of the turbulence of 
flight.  Runways, air pockets, micro bursts, vibration, and just rough 
dirty air would add a lot of dimension in my mind.  I think this is easy 
to do and could be programmed into a PC as a set of random events that 
could be user controlled in intensity and frequency.

My original suggestion of using show car air shocks might be a viable 
solution.  This is a system that is readily available, powerful, and 
presumably less expensive than building from scratch (if you count the 
learning curve).  Also the stroke length is more than enough to do what 
I proposed above.

Marv


On Monday, April 8, 2002, at 08:58 AM, Ben Jones wrote:

> Sorry guys for not replying earlier  i have been travelling around for 
> work , at home at last !
>
> I have not even looked at high compressed air and pnumatic rams to 
> controll a pit , i know they have  down falls , that can only be 
> overcome buy the use of lots of time , money and sweat  the three 
> things i have none of at the moment.
>
> The other thing that turned me off pnumatics , is that i work on some 
> of these systems for work when a part in the process breaks it usally 
> is verry expensive to fix ..
>
> Link trainers are a wooden simulator built in war time to teach nav 
> training  to british and australian pilots , the use 4 accordian type 
> of baffells to controll pitch and roll  , the greatness of this system 
> is that you only need a constant supply of air about 15 CFM out of a 
> compressor( really just a big blower )  , pipe  this air through a 
> couple of regulators out to the baffels and violla the sim moves ,
>
> the greatness of this system is that there is no hammering when the 
> valves or cylinder are actuated , because as the baffell inflates it 
> expands at a smooth rate .
>
> the controll stick in the cockpit have to slide regulators attached to 
> it one for pitch and one for roll  as you push the stick left to roll 
> left the right hand baffel is expanded and the left habd baffel is 
> exhaused at a slightly lesser rate of inflation to provide some 
> resistance to the inflating baffell vice - versa if stick is moved 
> forward back or right .
>
> in the links yaw is controlled by a motor and pulleys to spin the 
> cockpit around
>
> my next question does any one out there know if  any sort  of manuals 
> or books are avaliable on the link trainers , i have two trainers to 
> look  at but ....getting the time and getting access to the room where 
> they are stored on the base is a nother  thing
>
> i might bee able to gather some pics and sketches of the link if any 
> one is interested , but that is a lonk term project.
>
>
> regards
>
> BEN  JONES
>
>
>
>
> -----Original Message-----
> From: Andreas Fransson [mailto:andreas.fransson@post.utfors.se]
> Sent: Saturday, 6 April 2002 12:20 AM
> To: simpits-tech@simpits.org
> Subject: Re: [simpits-tech] motion systems for sims
>
>
> Stig,
>
> If you need large but short bursts of air, the way to do it is by 
> mounting
> an accumulator next to the cylinder. Put the valve between the acc and 
> the
> cylinder, and connect the acc to the compressor. Better make that a
> large-bore valve too.
>
> /Andreas
>
> From: "Stig Joergensen" <stig.joergensen@clearsky.dk>
>> Well you can get rid of the "bounce" feeling, by makeing a locking
>> mechanism on the actuator piston, the big problem as i see it, the air
>> preasure need for speed is going to be huge, i doubt that a normal 2hk
>> 300liters/min (8 bar) will do the job, even if you have one of these 
>> per
>> actuator. Well maybe in a standard turn it will be enough, but to get
>> the "bumpy" and the "sink" feeling on takeoff will require a lot more 
>> of
>> "air speed"
>>
>> /Stig
>
>
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