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Tandem AirBike Builder's Log

February, 2003 -- Fuselage finishing and misc.

Page 3


It has been very fun to get to the final assembly phase on the fuselage. Brakes are hooked up, throttle levers connected, control linkages in place. I like how all the control levers are located and how they feel. The two levers on the left are for unison brakes and throttle. On the right is the pilot's side-mounted joystick. Forward of the seat cushion is the passenger/student's joystick and throttle. All I need now is an engine and some instruments. In other words, all I need now is more money.


This view shows one of a pair of wedge-shaped phenolic shims I added to the teleflex elevator cable to modify the angle at which it mounts to the torque tube arm. As built, and as shown in the plans, I don't like the way the cable is forced to work back and forth against a permanent bend at this location. I'd rather see the cable bend slightly off its centerline in both directions than to be constantly cycled against a harder bend in one direction. Inside the C-shaped arm is another identical spacer, only with its fat edge down. Together, these shims correct the cable's angle for minimum bending throughout the joystick's pitch travel, and therefore, at least in my mind, minimum concern of compromising wear. Since the innards of these cables cannot be inspected, it's comforting to know that the motion of this critical cable is optimized in this manner.


Shoulder harness idea

Today I was showing my A&P boss the seat belts and shoulder harnesses that came with the kit, and telling him how I needed to order a harness system with safer buckles since I saw Richard accidentally unbuckle himself twice before we took off on my first Tandem ride. He thought for a moment and came up with a very simple, interesting and cheap solution. I'll try to describe it with verbal visual aids.

Visualize the strap coming out of the seat belt buckle -- the one you pull on to tighten the seat belt. Attach a 2" x 2" square of Velcro hook material to its top side and at its end.

Now visualize the other half of the seat belt -- the strap with the fitting that snaps into the buckle. Attach a strip of Velcro loop material, say 2" x 10" to the top of this strap and adjacent to the metal snap fitting.

Now visualize sitting on the seat and snapping the seat belt buckle together in the normal manner. Fold the strap with the hook material over the buckle and fasten it to the loop material on the other side. Voila. You have just safetied the buckle so that it won't pop open when your hand or arm drags across it. Comments?

On a related topic, Jack Moon writes:

Hi Doug,

I've noticed you've expressed concerns about the shoulder belts installed on the Tandem. An item that might be of interest is called a "sternum protector", available from Speedway Motors in Lincoln, Nebraska. Their item number 910-72353, available in red, blue, black and purple. Sells for $17.95. Secures the shoulder harness straps with a loop on each end and a quick-release buckle between. A free catalog is available. Their website is

I had notice the same problem in watching a TEAM promo video that I received with my Airbike and decided to use a sternum protector with my safety belt setup. Not much progress to report -- been trying to get retired but so far all I've gotten is just tired!

Looking forward to your future postings on your website.



Looks like a dandy solution, Jack. Thanks!



Here's a view of two AirBikes built by Paul Yarnall and a friend, using latex paint for the color coats over AFS primer.


Engine selection -- This time it's final (?)

I have lost my previously-stated interest in the Hirth F-30. Main reasons: A complete lack of desire to custom-build a bed-type engine mount for it, and exposure to some fresh rounds of Hirth-bashing from various sources. I am ready to commit to a Rotax 582 with my meager and hard-earned dough. I got outbid at the last second on a promising, lightly-used 582 on Ebay, and I haven't seen any others there since. If anyone knows of a used 582 out there, or of a dealer or engine shop that might deal in used Rotaxes, please let me know.


John's Geo Metro installation in progress

Meanwhile, Robert has solved the oil pressure difficulties with his HKS installation-in-progress, and John is installing his Geo Metro and beginning to paint his scratch-built metal assemblies. Keep the faith, fellow AirBikeheads!


Learn from the mistakes of others --
You won't live long enough to make all of them yourself.


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