Contemplating force feedback

After reinstalling the control columns and re-linking the rudder pedals and brakes, I started mounting springs and heavy duty drawer slides to implement static control loading like that provided by the excellent gear made by Northern Flight Sim. While searching online for parts I came across Ian Hopper’s force feedback site, where he sells hardware and software for implementing force feedback for mid size (think a heavy duty control yoke, like a CH Products yoke made out of metal parts) and larger cockpit setups.

After discovering this I became obsessed with adding this functionality to my simulator. My basement is fairly big, with nine foot ceilings, but I know I will never have enough room for full motion. Adding force feedback would lend a great deal of realism to my setup. Force feedback adds two characteristics simultaneously: dynamic control loading, so that the pilot feels the aerodynamic effects of turbulence and configuration changes, and autopilot functionality, so that flight controls move appropriately when the autopilot is engaged.

This may turn out to be the most challenging hurdle in the project. Ian has created an excellent, highly cost-effective solution to this problem, but he leaves it up to the buyer of his products to properly construct the mechanisms that connect to this controller cards and specified motors.

I have an advantage in that my flight controls were built by Boeing to withstand years of abuse, so all I really have to do is design three transmissions each using this small motor to create realistic forces on a larger scale. It is this particular problem that has had me stumped for the past three months, trying to specify the proper transmission in the most cost effective way. I know it can definitely be done, the question is how?



The reassembly process begins

The forward floor, finally in the basement
The forward floor section, reassembled in the basement. To allow access above and below the floor, the section halves were positioned vertically. To prevent the sections from tipping over, eye bolts were screwed into floor joists and secured to airframe structure with heavy duty cable ties.

After reinstalling the exterior door into the basement and securing the forward floor section to the ceiling, I re-joined the two halves by mounting more of my custom fabricated brackets onto various structural ribs. I had pre-drilled the holes for these brackets using cleco fasteners while the section was still in one piece in the driveway. I discovered early on that the metal fabricator who made the brackets did not punch the holes in identical positions, so each bracket had to be marked in order to match up to a specific location later on.

The throttle quadrant and radio pedestal sit on a large sturdy bracket that covers the big hole in the middle of this section. Luckily for me this bracket also crossed the centerline and was easily removable. Replacing the bracket added a great deal of structural stability to the reassembled floor section.

The next step was to reinstall the flight controls. The rudders and brakes were easily reconnected with control rods and hardware, and the roll axis was re-linked by connecting the threaded control cables.

Reinstalling the control yokes proved a bit more challenging as they are connected to the pitch crossover tube, a large heavy piece with a three inch beveled gear on each end. I had neglected to index the columns in any way, so when reinstalling I used two adjustable  sawhorses and a bubble level to make sure that each yoke was indexed to the same position.

Having neglected to make index marks on the control columns, they were lined up with adjustable sawhorses and a bubble level to make sure there were engaged to the same tooth on either side of the torque tube.
Having neglected to make index marks on the control columns, they were lined up with adjustable sawhorses and a bubble level to make sure there were engaged to the same tooth on either side of the torque tube.

Into the house

The forward section, reassembled in the basement.
The forward section, reassembled in the basement.

Once again it’s been a long, long time since I wrote an update, but work has continued over the past year.

Over the past three years I have had unbelievable luck in a complex cat-and-mouse game with the ninnies at Manassas Regional Airport. I always planned to bring the project home, but my hand was forced one rainy day last summer when I pulled the trailer over to Skyworks for an early morning rearrangement of the disassembled pieces. I finished this task around 7:30 am, and figuring that government employees probably wouldn’t be at the office that early, I drove my pickup with the project in tow up into the semicircular driveway leading to the secure gate onto the ramp. Standing next to the terminal enjoying morning cup of joe was none other than the airport director himself! One glance at the look on his face told me that there was no way to put the project back into the hangar as planned without getting busted, so I just kept driving, and ninety minutes later the trailer was safely parked in my driveway.

In the driveway, divided
After removing the control columns, throttle quadrant and dual-control linkages, the forward section was divided along the centerline to prepare for the move to the basement.

The trailer remained there for another two months while I spent days in sweltering heat removing the control columns and yokes, throttle quadrant, and all control linkages crossing over the centerline. All of this was done in preparation for moving the pieces into my basement.

Having finished the prep work, I gave the entire project a good bath with soap and water, then divided the forward floor section along the centerline with an angle grinder and reciprocating saw. This yielded two sections that were not particularly heavy but very bulky and awkward, so I bribed three friends with promises of burgers and beer to come over and help move everything into the basement. This was made easier by temporarily removing the sliding double door.

The two halves of the forward floor just after arrival into the basement.
The two halves of the forward floor just after arrival into the basement.