John's Plane Week 4
Week Four Trikes, Brakes and Engine Mounts
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
July 28, Tuesday
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
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
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
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
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.