Showroom DHC-2 Beaver (Fully functioning cockpit on 4 dof motion platform)

I have been planning to build a simulator cockpit for a while now, and over the past couple of weeks have started taking definitive action towards fulfilment of the dream (other than just researching)

I have decided to build a de Havilland DHC-2 Beaver, with fully functioning cockpit, on a motion platform. I found a nice looking model of a Beaver on Sketchup's 3D warehouse, and started preparing plans for the simulator based on that model, as well as some plans I have. I would really like to try and find more detailed plans, especially of the cockpit and instruments.

At the moment, the plan is looking something like this.




I thought that I should try and go for a balanced frame, as this would require less power from motors and electronics. The idea would be to have Roll, Pitch, Heave and Surge. The Roll and Pitch angles should ideally pass throug the centre of mass of the combined cockpit + 1 or 2 pilots... I must admit that the whole sim is starting to look a little on the large size. I am not too pressed for space, but there is a limit to what my wife will allow

I estamate the combined weight of sim and 2 pilots will be around 350kg.



The plan is to build the outer gyro frame from steel hollow section, whicls the inner frame will be made from aluminium. The body will have to be made from a combination of 3 mm playwood and 1 mm or 1.6 mm Aluminium sheet. the Roll and Pitch motion will happen around pillow block bearings. I am hoping that I can have Heave and Surge by moving the frame in something like SBR16 linear guides.



The detailing of the frame is only done roughly. Lots of bracing and strengthening is still required.






I'm thinking that pillow blocks should give a good motion for the Roll dof,

and for the pitch...

There are still a few issues with regards to the amount of motion I will be able to get, but from my research over the past few months it seems one dosen't need an exorbitant amount of motion, anyway.






The interior of the sim will require quite a bit of work, also. I might even start off by building flight instruments and controls.



I'm hoping to run the sim with Simtools and XPlane 11. I do however have a very long road ahead, and will need a lot of community support. From what I have seen here at xsimulator, I think this is the place to get that as well. Any comments, suggestions, alternatives, questions and remarks will be welcomed.

I was hoping to stick with DC. I'm thinking about something like Roland's actuators...
http://www.simprojects.nl/diy_motion_platform_v.htm
I'm hoping that by going as close as possible to the c.o.g. I won't be needing huge motors.

@noorbeast , maybe you're right, I could can the Surge and Heave, make 2 dof frame, add G-seat and thereby reduce the complexity significantly. Would you say the G-seat is a good substitute for Surge and Heave, or is the actual Heave and Surge motions on the motion platform better i.e. more realistic?

I was thinking a combination of motion platform surge, followed by sustained g-seat pressure woul give more realistic effect. Same for heave. Does anybody have more experience with surge / heave vs g-seat vs both combined?

A well implemented G seat would work fine in this situation at a much lower cost/complexity. Heave would be the only DOF needing decent power, but still within the capabilities of reasonably sized DC motors. For not much more cost you could also drive two seats. G-seats or systems can do allot of things that a normal motion seat just cannot do - extended Gs for one (which is why I use both), they also do not have issues with washout, or inertia induced delays. From what I have learnt/experienced, I often wonder why they are not used more?

Unfortunately unless you have implemented a well designed washout (not simple) big movements can induce issues in a motion seat as the rig moves back to its initial position (not a issue in a G-seat). There can also be delays induced due to large inertia compared to a G-seat.

So I own a 6DOF, but am saying build a G-seat/system? For a big rig (especially a two seater or more) where normally expensive AC motors and controller/drivers would be needed to suitably move the large mass , you cannot beat a G-seat. I have run my 6DOF with only the G-seat function turned on and the immersion with VR is still very strong. 6DOF motion seats do look sexy as they move around, but IMO are not really really needed for good immersion. Note that realistic surge is not easy to do in a normal G-seat, but I have got around that with my Harness/bowden cable system - see my build thread.

If you do decided to build a G-seat and your not using VR, recommend that you ensure that you cannot see into the outside world from the Cockpit, as it will break immersion.

@SeatTime , thank you for your detailed and very informative responses above, i really appreciate the advice.

I have little doubt that I will be building 2 G-seats. I don't think its easy to simulate sustained G force effect in any other way. The only thing is that I am still not that clear on adding Heave and Surge. If I read @SeatTime post correctly, he uses a combination of G-seat and 6 dof motion.

My thinking is as follows:

1. Plan for everything neccesary or desirable as it will probably be easier to leave things off / simplify the design later, than to add things later,
2. I would ideally only build a simulator once in my life, so I should rather try and do it right,
3. About immersion, you know that feeling you get in your stomach as you initially lift off the runway... or the feeling you get when going through some turbulance (vertical movement) Well, my thinking is that those effects will be hard to simulate with anything other than actual heaving motion. Thing is, I don't know as I have never bern in a simulator in my life.
4. Other effects, such as sustained climbing or turning will be easier to simulate with a G-seat.
5. I fully understand @SeatTime comments regarding inertia. I have been thinking of getting lifting assistance for heave using bungee chords.
6. Also, about washout and returning to starting position slowly, does Simtools make this possible?

Lastly, I was thinking that if I try and get the pins for roll and pitch as close to the cog of the system as possible, I could reduce the amount of power i need.

As I do have a 6DOF, I do not need to implement heave in the G-systems, but it is not hard and just requires moving just the seat or fitting a paddle under the seat. From experience do not use lifting assistance - springs etc (unless you really have no choice and are happy to live with the consequences) as similar to springs in a car they will cause oscillation issues. A reasonable size and suitably geared DC motor (around 300w - 50:1 ) should lift most people in regard to Heave OK. @noorbeast has heave axis on his seat and my old sim had a DC motor driven single paddle built into a race seat. Both worked fine. As for lack of experience - well there is less to get wrong and the costs risks are much lower in building a G-seat. I although would never recommend either of these complex projects to a new simulator builder - although it depends on your background. Simtools does have some washout filters, unfortunately I have never been able to get them to work how I wanted/expected. As for surge - as stated I use a different G-system that I developed. Unfortunately the details of that system may not be available for public release, so you will have to take that into consideration when making any design decisions. As always - I'm just offering advice and will not guarantee that any of the above will work as described. All decisions and risks must be yours.

@SeatTime , absolutely my friend, I understand 100%. You are giving advise (wich I greatly appreciate) not giving guarantees.

The nice thing about it is that it helps me to organise my thoughts and to gather ideas