full length ?

first post - so, hi all - i've been inspired to create a motion sim - have been using a static chair with rfactor for a while now - i use it for practice of tracks near me, sydney australia, as i also race a clubman and a lotus elise.

anyway, i've been looking at various designs and one thing that bugs me is having the foot plate / pedals and wheel seperate from the seat movement -

i have the skills and equipment to weld together a custom frame - this is no big deal - the question is more about the measurements and how i work out where the centre of gravity is - is there a way to work this out, or do i just build the seat / pedal / wheel frame and base with an adjustable universal joint (back and forth) to find the best c of g - from this i'd then be work out the actuator placement ... ???

base will be made from 25mmx50mm 2.0mm RHS mild steel and seat frame to be made from a combination of 25x50x2.0mm RHS and 25mmx25mm 1.6mm RHS

i've already ordered (and received, thankyou bill) the scn5's, spherical rod ends, psu and serial convertors and steel .....

the idea i have is as attached ...

Hello Barrym!
You can calculate the location of center of gravity. You just have to know weight of each component and components’ center of gravity location. When the rig is balanced, the moments caused by weight of the components x lever to reference point will reverse the effect of counterforce x lever located in CV. For example take your pedals as a reference point and use the following equation:
f(wheel) x l(wheel) + f(driver) x l(driver) + f(seat) x l(seat) + f(frame) x l(frame) =f( counterforce) x l(counterforce)
For example f(pedals) means just pedal’s force (in this case simple weight will do), l(pedals) means the distance from your reference point (wheel) to pedals
Counterforce is the sum of all your components and again, L stands for the distance between pedals and CV-joint. => counterforce=f(pedals!!!)+f(wheel)+f(frame)…..
So it includes also pedals weight which isn’t in the first equation as it’s our reference point.
L(counterforce) is what we want to find out and it’s the only thing we don’t know in this equation. So simply dividing both sides with f(counterforce) gives us:
l(counterforce)=[f(wheel)x l(wheel)+f(driver)x l(driver)+f(seat)x l(seat)+f(frame)xl(frame)] / [f(counterforce)]

Feel free to ask if something is unclear in those equations. I attached your picture bit modified to clear things out. All the distances are measured in horizonal direction as in picture. And I don't think it's a bad idea to add a possibility to adjust the location of CV-joint, as always maths don't apply to reality :yes: .

And about your picture, I think you don’t necessarily need to use those sideview triangular braces in your frame. By using 25x25 tubes it would be very stiff yet quite heavy structure. For example, in my sim I used two 20x20x1,5 tubes to support pedals. Now I think they could easily be 15x15x1,0 and still enough rigid. Of course I have separate support for wheel. If interested, take a look how I did the frame: 3-dof-sfgt-style-simulator-t2820.html