Sim Rig Engineering - What are the Real Requirements?

[Jean-Pierre Sarti]

There seem to be three basic approaches to attaching the uprights to the base of a sim rig:

(Screen captures from RigMetal and Heusinkveld.)

Most rigs are one of the first two designs, while the only one I know of that uses the third is Heusinkveld's.

Another difference is that the Heusinkveld design puts the short cross member at the wheel uprights, where others typically put the cross member under the seat. Niels Heusinkveld is a Real Engineer, and his rig is "designed using CAD and FAE analysis", which makes me think his design is the one that provides the stiffest wheel support.

There's also a large difference in the size of the channels used in various rigs. I'm not an engineer, but given the strength of 8020, wonder whether some rigs use unnecessarily large (and expensive) channels, particularly with 8-10 Nm wheels and good-but-not-extreme pedals (e.g., Heusinkveld Sprint).

Are there any real engineers out there that can respond to my ramblings?

Thanks!

 

[Deleted member 197115]

I am surprised HE was able to achieve stability without going custom brackets.
The second option should be the most stable. this is what Sim-Lab is using as well.

 

[metalnwood]

I like the second picture, I see a lot of companies using the third picture as it certainly saves costs in making custom parts. I dont like the first, leftmost option.

Not many people are going to design the optimally engineered rig from 8020 and call it that. By the time its all said and done people will still look at the over engineered one and pay a small amount more. That seems to go for anything

 

[blekenbleu]

SimLab uses 4 screws to secure their brackets for uprights to 8020, which matches Heusinkveld.
A potential ergonomic benefit of spacing shifter extrusion slightly more distant from the seat
could be accomplished by connecting to that extrusion to the wide side, rather than edge, of the upright.

 

[Neilski]

Would be interesting to test them all (Either IRL or something like Ansys.)
I agree that #1 ain't very good, for side loads in particular, but I suspect that #3 may actually handle them better than #2 - it really depends on that plate (thickness, material). #2 is likely to be better for forward/backward loads (providing my brain is oriented correctly), but both #2 and #3 are likely to be plenty good enough in any event.

 

[Deleted member 197115]

It's not just number of screws mounted to the main frame, we are looking at solid thick metal bracket with precisely matched to screws holes bolted to the back of upright and then to the main frame. One piece, versus 4 individual standard angle brackets with slots for bolts that can wiggle around under pressure.
As metalnwood said, sim-lab can be overkill but it is rock solid when using 25nm DD wheel. Don't have experience with HE rig, I am actually surprised they still offer those, they are quite overpriced comparing to others..

 

[Jean-Pierre Sarti]

Looking at the Heusinkveld rig manual, the side and lateral channels are 160x40 and the verticals are 120x40. Obviously built, like the P1x to handle the strongest wheel, motion platform, etc. But for folks with average equipment (e.g. 10 Nm wheel and Sprint pedals, no motion platform), how much smaller could you make them using the same basic design?

Another point, where are the actual stresses? I'm sure any channel wouldn't be stressed by the force exerted by the driver on the pedals. But the wheel... if we imagine a box with the wheel on top, it has to be stable fore and aft, but I would think the real force the frame is resisting is side to side.

Comments?

 

[blekenbleu]

how much smaller could you make them using the same basic design

Karl's first Sim Hound cockpit review, since deleted, using 6030 main extrusions,
needed a brace added to suffice:

 

[blekenbleu]

real force the frame is resisting

Unless driving single-handed, main stresses are resisting steering torque and (load cell) brake pedal forces,
depending on whether/how hard one exercises shifter and/or hand brake.
Barry at SRG comments that he tends to push on the steering wheel, so fore/aft forces on wheel base and uprights.

P1X and cousins are justified by motion actuators that can move nearly all load to a single corner.

 

[blekenbleu]

bolts that can wiggle around under pressure.

If P1x bolts to uprights wiggle, brackets must be removed from the chassis for access to retighten.

 

[Deleted member 197115]

If P1x bolts to uprights wiggle, brackets must be removed from the chassis for access to retighten.

Yes, did it happen to you or anyone you know, I only have mine for about 2 years?

 

[blekenbleu]

did it happen to you

In fact, the AccuForce wheel stand with 10 series legs and 8020 only for wheel base mount
has no loose screw issues in brackets less substantial than Heusinkveld's,
which I also expect has no issues if properly assembled.

 

[Jean-Pierre Sarti]

Karl's first Sim Hound cockpit review, since deleted, using 6030 main extrusions,
needed a brace added to suffice:

Thanks for calling that to my attention. I think there's a lesson there: the stability was improved by adding a lateral brace across the bottom of the wheel uprights rather than by changing the size of the extrusions. Sim Hound's approach reminds me of Colin Chapman's "Simplify, then add lightness” approach.

 

[RCHeliguy]

I believe the SimLab P1 chassis is one of the very best out there. I understand engineering for minimal weight, but I will say that over the years I would have been totally screwed with the HE chassis and would have ended up replacing most of the chassis to enlarge it or I would have just sold it.

Neil doesn't like motion and his chassis isn't set up for it. My NLRv3 couldn't fit inside his frame and it isn't set up as well for full chassis movers. It is very narrow, so little will fit in it. My P1 is packed very fully. I also don't think there is adequate room for serious tactile systems.

It is truly minimalist.