Kit Building: Doors
The instructions with the doors may be greatly aided by photos of doors
on completed Challengers.
The biggest challenge with the doors is getting started. Don't be
fearful - just wade right in. You might drill a hole or two in the
wrong place, but it won't matter in the end. Doors are for looks
and to keep the elements out - they are not structural per se. Of
course, you don't want them falling apart in the air and whipping
through your propeller and tail section either, so be careful!.
I got some very basic directions from Kris Falk that
added to what came with the kit and just waded right in. It wasn't
all that hard, and I was pretty proud when builder/inspector Kris Falk
said my door frames were the sturdiest he'd ever seen - even before the
lexan got attached.
In our opinion, the majority of any
mistakes you might make will be hidden by either lexan, paint, or a
door hinge (if you drill a hole or two in the wrong spot like I did!
This is especially true if you order you plane with the tinted lexan (advised)
and paint your cockpit and door tubes black.
bare in mind that the tubes for the doors are probably not perfectly identical from
one kit to the next. Close, but not perfect. I doubt the
airframe is exactly the same either. This means that your
doors will fit your Challenger. They may not fit every
Challenger. Borrowing doors from somebody else's plane as a
pattern may help you with the concepts, but not necessarily with
measurements! It may be good guidance, but they will
not likely fit perfectly.
trick is to build the doors on the airplane!
really not that hard once you get started. Just allow
yourself lots of time and don't get impatient.
Your first door might take you a day. The other side will take
half as long as the first.
more thing, all airplanes change shape slightly once they're airborne
and the weight shifts from the landing gear to the wings. So guess
what, the doors don't need to be built to exacting tolerances because
they will fit a bit differently in the air anyways as soon as you lift
The first thing is to separate all the tubing that came
with your doors. There will be six matching pieces
per side that are labeled with a felt pen showing numbers from 1 to 6.
Assemble yourself some 1/8 inch drill bits, some packing
tape, and a wheelbarrow full of patience.
You'll need to make yourself a few spacers - about 1/2
inch think is just right. I used some cardboard. Some folks
cut the small square lexan samples provided with the doors into strips and use
1. Install the Top Frame &
The instructions in the kit for this part are generally pretty
good, although they are backwards relative to the front and back of the
assembly. Not a big deal really, and most door frames are built
per the instructions (i.e. backwards!). You'll just have to modify the front seat
belt bracket positioning. My Challenger door frame is installed per the
Here are some shots of
the top frame - at the front, middle and rear.
My top door frame is installed exactly per the manual
I moved the mounting for my front seat belt back a bit to clear
the midpoint support on the door frame.
You won't need to do this if you flip the door frame end for
end when installing.
I learned this from a seasoned builder named Bruce Brown.
The Top Lexan
Wade right in - this stuff is actually very easy to cut.
Just scribe and snap - just like it says in the manual.
Use a straightedge and guide a fresh blade along the line you
want to cut.
|This piece needs some notching, so plan
on tinkering for a bit!
|Put the piece over a table edge and
press - it will break nicely right along the scribed line. I
even found that with subtle adjustments I could even follow along on a
|Please note my flaperon control is
disconnected there in this photo - I took it off so I could test fit
|That reminds me - I have to make
another hole in the lexan to reinstall the flaperon control!
2. Install the Front Windshield
|I did a lot of fiddling to pick just
the right spot. Mine is pretty much where the longeron starts to
curve inwards. You can see the rear seat rudder pedal and
this shot. Note that the tube does not angle back when
installed - it is hanging free in the photo as the top has not yet
been attached. Use a Cleco or Aluminum rivet as you have to
take this off to do your fuselage fabric.
Note the judicious use of packing tape prior to drilling and
|Now, here's that same part at the top.
It has here been trimmed for length and angle.
You can see the top tube in this shot as well.
|Here is the bow tube and the top tube.
|Note the use of felt pens
("Sharpies") for marking. PLEASE, no pencils on
aluminum airplane parts - pencils start corrosion and stress
lines immediately on aluminum.
|Cutting parts. Just eyeball the
angles, cut gently with a hacksaw and file edges smooth. Go
easy with the vice - you don't want to squish your door
tubes! You can just hold the tubing with your hand and saw
3. Fit the Top Tube
|Here's one of those chunks of scrap
lexan as a spacer. I used about three of them along the
top of the door, and two in between the door and the front tube.
|Here's the rear end of the top tube.
4. Fit the Bottom Tube
|I used three strips of cardbox taped
together for my bottom spacers. This worked out to about
half an inch.
|Tape and cardboard! A bit here
and there, and the door frame holds together quite strongly so you
can drill holes!
5. Fit the Front, Rear and
|You can see here about how much
clearance I left between the bottom tube and the windshield frame
(bow tube). My front tube just went on top of the bottom
6. All Taped and Ready to Drill
|Just before I started drilling holes
and clecoing (is that a verb?). It is actually quite sturdy
at this point.
You'll see the angles I decided to use and the placement of my
middle tube. All up to the builder! I like parallel
lines, so that's how I placed things (more or less!).
While doing a nice job is important, flying the beastie is the
real important thing, so get building!
7. Drill and Cleco
8. Riveting (Isn't it)
|I didn't take too many pictures of this step, but if
you're this far along, it is pretty hard to mess up.
For one to many Clecos ...
Re drill a bit if rivet won't
|I elected to use stainless steel
rivets. Overkill I know, but my doors are very
sturdy. Will help when putting them on and off in prairie
PS - yes that is one of two completed wings - ready for paint -
in the background!
Back on the Plane to install the Lexan
the door frame on the hinges. lexan installation is a a
two person job - at least at the start. One person holds the lexan,
the other lines
things up, and drills the first hole or two, and pops in the clecos.
Kris popped by this week and motivated me to get on with it. We
had the lexan on this door in about half an hour!
|I held the lexan up and Kris went to
the other side of the plane to make sure it was in the right spot
(front to back). We just lined it up with the hinge pins
which makes it even with the top of the door frame.
Once we had the lexan pinned to the door frame with two clecos,
we carefully removed the protective backing from the lexan in a
strip where the door tubes line up. This has to be done very
carefully so as not to scratch the lexan. We pulled a bit
away and carefully sliced it with an Olfa Cutter a couple of
inches away from the lexan.
|We went right across the top, and then
worked our way down with one hole and cleco in each vertical tube
at a time. This way, as the door starts to curve, one person
can hold the lexan tight against the door while the other drills
and clecos. I would imagine that if you did all of one
vertical tube or the bottom first, you could end up with a warp in
the lexan and it would not fit tightly against the door tubes.
We went across the bottom tube last.
You might be able to see the small piece of lexan we used for
spacing the rivet holes in this shot if you look really
close. Our spacing is about 4" which worked out very
evenly on the door.
The Fine Print - Caution
Ideas, illustrations and photos are the author's own
work and are for information only.
Builders of Challengers should always follow the Quad City manual.