John's Plane Week 4
Week Four Trikes, Brakes and Engine Mounts

July 27, Monday

When I arrive at Mark's about 1 pm, he is rebuilding B1-RD wing tubes a customer had bent in a weekend "incident." By 3 pm we are working on my project. We gather components for the steel trike cage. There are down tubes and "big man bars" to be sanded, cleaned and painted. A bit repetitious since once we begin, we usually restock Mark's supply as well as create the one or two parts we need. Economy of scale, the MBA's say. But we switch jobs before the work gets boring and there is always satisfaction in doing a good job.

We build a custom axle for my bird. Since I plan to teach with this plane, Mark suggests an axle constructed of three tubes, two full length and an 18 inch sleeve at either end where the fittings will be located. Mark replaces the aluminum axle stub so commonly broken in QS trainers with a 4 inch chromoly steel axle run through an aluminum bushing 2 1/4 inches long. All these parts we manufacture from stock. The rear down tubes will join the tri-bar with a fitting Mark must turn on the lathe. You can see four of them sitting on the lathe in this picture.

We complete the axle, tighten all nuts, locate the tangs and saddles and all fittings properly. Tighten the nuts with a ratchet until the counter wrench stops kicking the palm of your left hand--then tighten only a bit more--half to three quarter turn. don't distort the tubing, yet make sure all parts contact snugly. A delicate operation.

After an iced tea break at Linda's we pick up more parts at the warehouse. Hegar wheel parts, 2 sides for three wheels, one side has an air valve hole, six each 5-10a bolts for each of three wheels. Three tires, bearings for three wheels. For the first time we take a couple of items from Mark's stock, a front wheel fork and one inch tubes precut and drilled for the axle struts. At home we assemble the wheels as tubeless tires. Each wheel hub receives an O ring on either side for a tubeless seal. A drop of oil on the O ring and it slips nicely into its groove. Oil the tire valve and slip it through the rim from the inside out. A slight pull and it pops satisfyingly into place. Mark shows me how to strap the tire around its outer circumference to force the tire to the rim and then fill it with air.

I set my tires aside and mount the tangs on the tension struts, Two bolts each. Make a left and a right side and it's lunch time.

After lunch Mark puts me on the lathe milling brake spacers, fat aluminum washers or bushings, from a round bar of aluminum. I'm a bit nervous about operating it. He demonstrates by mounting the stock through the jaws of the lathe and drilling into the end of the stock. First he uses a center drill, which "wants to find the center" Mark says, then follows the small starter hole with the size drill required. Funny to see a drill enter the turning stock. The drill bit doesn't turn so appears to me to simply be sinking into the bar. The turning round stock is smooth and hardly seems to be turning at all. Obviously, motion is relative. You can drill by turning the bit or if you can manage it by turning the material to be drilled, as in the case of a lathe. Next he marks with his micrometer a 4.36 mm length on the stock, give or take a thousandth or two, and cuts the first spacer, catching it in his hand and flipping the hot metal onto the lathe case. He then turns the lathe over to me after a safety lesson, and I'm on my own. I cut several when Mark checks my work and finds I have cut several oversize. He shows me how to mount them in the jaws of the lathe and remove the exact amount necessary. The lathe is a beautiful machine, cutting a smooth surface in such close tolerances you can't even feel some of the errors with your fingers. Only the micrometer reveals them.



But the lathe is also dangerous--its knives, the cuttings spiraling off the stock, or just a careless move by the operator. Not everyone should use a metal lathe, I'm thinking, but I am pleased with my own effort and glad Mark pushed me in that direction.

Mark has projected eight weeks for this project. I think we can do it but I don't want to let the goal of completion take away from the pleasure of building. I am changing my attitude toward ultralights as machines. Building it myself reveals starkly that no government program can protect you from a manufacturer's mistake. We ultralighters are responsible for our own safety and the safety of those on the ground who could be injured by an ultralight out of control. To say nothing of property damage. Mark and I "am" the manufacturer. Next picture shows me sitting among some of the parts we have ready to assemble.



So, lets put some of these parts together. Mark takes extra care to use exactly the right bolt length and will not correct an overlong bolt with washers. I have seen kit planes assembled with as many as six or seven washers because the kit supplied bolt was too long or the builder used the wrong bolt. I have also seen nuts bottomed out on their bolts because the kit directions specified a 15 when a 14 was required. I try #3-12, tighten the nut--won't do 2 to 3 threads must show--#3-13 is required. Mark recommends thin nuts where the nut is only holding the bolt in place. Regular nuts are needed only when they are carrying load, he points out. "Heck, a piece of chewing gum would hold a bolt in place, so why use a hundred nuts heavier than necessary?" he argues.

Back to the warehouse to collect brakes, cut the root tube--a solid step forward, I feel, load the truck and knock off for supper. We collect a couple of steaks, potatoes and onions and Mark demonstrates his cooking skills on a grill at the airstrip. Delicious.

July 29, Wednesday

Breakfast at Dairy Queen, I learn Mark has already drilled my root tube this morning. Energy plus, that man. I need my coffee.

We assemble the basic trike. We bolt the tension struts and nose struts to the steerable nosewheel and to the tri-bar undercarriage. We mount the wheels to the axle and attach the axle struts to the axle and the tri-bar. We fit the down tubes of the front A-frame into the tri-bar and assemble the rear A-frame and its downtubes and attach the rear care A-frame to the tri-bar with the fittings Mark has milled previously. By 10 am we mount the two A-frames to the root tube. We stop to take a picture.

We tighten up a few bolts and add a component or two and lo and behold: the trike is well begun.



Next, the brakes. The brake assembly must be modified to fit the Hegar wheels. This entails welding, milling, drilling, sandblasting. I will list the time consuming steps:

1. disassemble the brake assembly, 2. On the lathe, enlarge the center hole on the back plate to accept a 2" steel sleeve that will fit onto the axle, 3. enlarge the inner diameter of the sleeve on the lathe to fit the axle 4. drill a bolt hole through the sleeve for mounting on the axle, 5. Weld the sleeve to the plate, 6. weld a drilled and slotted tab to hold the brake adjustment tube onto the backplate. The brake cable passes through this tube, 7. Sandblast this backplate assembly to give it a finished look, 8. reassemble the brake assembly.

Sorry if this seems tedious, but I found it fascinating in this respect. When you purchase such a part from a supplier as an after market item, you will be astounded by the price only if you don't know how much labor goes into these modifications. Once you see and help produce the modified item, you wonder why it doesn't cost more. Here is Mark welding the sleeve to the backplate.



And here is a close up of the brakes after the welding with the sleeve and the tab, complete, ready for cleaning.



I am pretty pleased with myself, by the way. I had never done a brake job on a car and so all this was new to me. But I learned to spring the shoes out and snap them back in quickly without getting my fingers in the way. I suppose a skilled mechanic would smile at my enthusiasm, but, hey, when you get to the Big Apple for the first time, go right ahead and gawk. Those buildings are tall!

Later, I install the seat support and the pedal bar on the nose struts. locating both these items to suit my preferences. My legs are considerably shorter than Mark's, so I sat in his trainer and estimated how many inches forward I would want my own seat. Before we drill and bolt in the seat we will measure again. I drill and bolt the rear nose wheel plate holes through the tension struts--tension for me, too. Can't get this wrong. Under Mark's supervision, I do it right. Whew!

This evening, I close out the day by working on this web site. As I look over my working notes I am amazed at how many different activities I am involved in each day and how easy it is to forget which order I did them in.

July 30, Thursday

Today I work on the motor mount. It is Mark's design and one of the most significant modifications from the Quicksilver design on my plane and others Mark has built. More on this below. This particular mount was welded some time ago. My first look at the mount tells me I have a labor ahead of me. Chromoly rusts usually only on the surface, but this cage has been sitting around for a while. I begin sanding but quickly realize I'll need help. I use a round wire brush in the drill to get most of the rust, and by lunch time I have the cage cleaned and wiped down with a solvent. Mark spray paints the cage with anti-rust black paint. Here are a couple of pictures.

While I am cleaning up the cage you see above, Mark has been milling a mounting plate from heavy aluminum plate. This is the standard QS shape but it will be mounted on the bottom of the mounting cage under the wing. The engine will sit on lord mounts in their usual QS place on the plate. Here is a picture of the plate with the Lord mounts in place.



Mark and I unpack the Rotax 582 that will power my plane. Without all its supporting parts it looks small. Notice it is water cooled and so has none of the cooling fins which make a 447 or any air cooled engine seem larger than it is. Here are two views of the engine. First from the intake side:



And now from the exhaust side:



We set the engine temporarily on the plate to check for fit and set them aside. We insert fittings into the gas tank, including two for an auxiliary seat back tank. Fuel from the seat tank will be pumped up into the overhead tank. The second fitting is for overflow if the pilot forgets to shut off the pump.

Cookout again. Great steaks. We watch a Seinfeld rerun as we eat. I'm feeling really good about our progress.

July 31, Friday Mark mounted the engine mount cradle on the root tube before I met him for breakfast. Here's a shot:



Then we place the engine in the cradle on the mounting plate.



You can see how the thrust line will be lowered by Mark's cradle design as compared to the QS over the wing mount. Increasing the throttle setting in flight will not lower the nose as in over the wing designs. Note, also, the engine will not be up on the wing, spoiling the airflow. This is no longer an experimental modification. It is tried and true. Mark has shipped this part around the country and even out of the country. It is simple and strong. Notice also how accessible the engine is. You can inspect the engine or change plugs, for example, standing on the ground.

Four down tubes will run from the four corners of the cradle to the axle. The two front down tubes are triple walled and of course shorter than the stock QS tubes. Mark cuts the triangular plates we need for the harness support on his plasma cutter. I cut two 4 inch steel tubes to which the triangles will be welded. We clean these up, polish the inside diameter and slide them over the front down tubes and mount the down tubes.

The rear tubes are single tubes. QS designs don't have these at all. We measure for a seat support down tube and cut and drill it. This too, connects to the bottom of the engine cradle. Now I can climb aboard.



I complete the brake mounting to close out the day.

At the end of week four, let me review the custom items on my trike. These are not as costly as they would be if I bought a kit and purchased them as after market items.

1. Mark's engine mounting system. Purchasing a kit then modifying it this way would simply be cost prohibitive. Of course, you could buy a used Quick and modify it this way. 2. Triple walled front down tubes 3. Triple walled axle 4. Steel axle stubs 5. Hegar wheels . 6. Harness mounts in place on down tubes

This is the end of week four of our estimated 8 week project. Next week we live with the trike.

NEXT WEEK

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