Don Dewey's Royal Coachman Build.

Anything with a propeller
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

I am doing a build log on RCG, Vintage Builders section, thought I would share the build here as well.

I've got the materials for the “Royal Coachman”, it is a simple and, in my eyes, a cute little 2/3 channel trainer for 09 to 15 power, designed by Don Dewey, the plans were published in RCM magazine 1965 and the kit manufacturer “Sterling “kitted the model a few years later in 1968.

Image
This is the 1965 plans published in American RCM magazine. Both the
1965 RCM plans and the Sterling kit plans are available from Outerzone.

https://outerzone.co.uk/plan_details.asp?ID=1302
https://outerzone.co.uk/plan_details.asp?ID=9845

I first came across the Coachman when I joined my first model aero club back in 1971, fellow club members Col and his son had built one each and flew their Coachman’s every Sunday for years. I fondly remember Col’s model being chased by a very small nesting bird, the wagtail chased the Coachman through loops, rolls, and low passes down the runway all to the amusement the other club members. A Coachman built by another club member, Ted, scaled up his version from it’s 41” to 56”, fitted it with ailerons and powered it with an OS40, still a great flyer in its larger size.
Never got around to building a Coachman, till now.

Image
Most of the wood, the OS15 and the steerable nose leg. To The Build.

With the plans downloaded from Outerzone, and a quick trip to Officeworks for printing, $5.40 for two full size copies of the plans (one to build over, the other to use for templates). Some changes will be made in my build, the right and down offsets of the engine will be built into the airframe, a steerable nose leg instead of the fixed leg, the wings will have the lower spar moved forward under the upper spar, a sheeted D box to the spars and cap strips from the spars to the trailing edge, I’m doing this to save a little money, and a little weight, plus, I don’t see any need to fully sheet the wing.

A kit of parts for the fuselage is first cab off the rank (next post), I’ve worked out that 3mm or 1/8” added to the front of the left fuselage side gives 2 degrees right thrust and moving the bottom of the firewall back 4mm on both sides gives 3 degrees down thrust.
Cheers,

Dave
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Re: Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

I always get two copies of the plans, one to build over the other to cut up for templates.

Image
I cut the templates out.

Image
Temlates ready for spray adhesive, just to find I didn't need them.
I will need the wing rib pattern though.

The fuselage sides I just measured and drew the pattern on the balsa with the down and side thrust adjusted into my cuts.

The tailplane just happened to be 100mm deep, so all I had to do was cut to length , the elevator, fin and rudder like the Fuse sides, I drew the pattern on the wood and cut.

Image
The parts I've cut so far.

The ply formers being plain square shapes, again I drew the pattern and cut with an X-acto razor saw.

It seems I will not need the second plan, the design is so simple I didn't need the spray adhesive or the patterns I cut out, just measured the plans and sketched the cut lines on the wood for everything.

The ply for the formers is a type of light ply, I'm lucky, where I work we get very large crates made of the stuff, great for formers but not firewalls.

The ply for the firewall and fuselage bottom will be a very nice aircraft grade Birch ply from Finland, I use the Birch ply only where I need great strength in a model.
Cheers,

Dave
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Re: Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

First off, I just realised this is the first model in over 50 years of model building, I've built with a tricycle undercarriage, once built a model for a club mate but never one for myself. All my models are tail dragger’s.

Anyway,

Image
Assembled parts so far.

Started to assemble the Coachman, tips on the tailplane, front and rear ply bulkheads, nose doublers and the balsa centre bulkhead. I’ve made ply braces for the rear wing dowel, and a vertical load spreader for the rear main gear dowel

Image
The three bulkheads used CA and used epoxy for the doublers.

Image
Here you can see the rear wing dowel ply braces and the vertical load spreader for the rear LG dowel.

As I mentioned in the opening, I am building the 2 degrees side thrust and 3 degrees down thrust into the nose, finer adjustment if needed can be done with a few washers. in the photo, the fit is very nice. The diagonal line on the firewall indicates I plan on mounting the engine at 45 degrees, this will lower the exhaust enough to flow under the tailplane using a silicon exhaust extention.

Image
The firewall just sitting in place for the moment, not ready to glue in yet.

Comments and advice welcome all the time.
Cheers,

Dave
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Re: Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

Here I'm using some 4mm triangular stock in the long corners of the fuselage, glued in with aliphatic resin. Will be sanding some nice 3mm radius round corners when finishing the fuse.

Image
Triangular corner strengthening from the rear LG dowel to the tail, using aliphatic resin and pinned in place.

The humble cloths pin, one of the most valuable clamps I use. I've glued in the wing mount doublers, again, using aliphatic resin, don't use everyday PVA glues anymore, had a wing melt on me a long time back in my early days of building, a very hot and humid day at the field, watched the wings slowly droop while waiting my turn to fly, water based PVA glues, (never again).

Image
Wing mount doublers pegged in place using "Great Planes" aliphatic resin, longer drying time but strong and sandable.
Cheers,

Dave
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Re: Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

I pulled a sheet of sandpaper through the tail end of the fuselage, reversing the paper after drawing it out each time. This gave me a nice sizeable 10mm by 13mm gluing surface to hold the tail sides together, now the block used to join the tail sides is not needed, and, saved a few grams from the tail. I sanded the tail to 1/8" wide to match the thickness of the fin and rudder.

Image
Just after gluing, two pegs clamping the sides together.

The line marked across the tailplane mounting area was drawn when I centred the fuse, I used a straight edge (a 12mm wide carbon fibre strip) lined up on the centre of the fore and aft ply bulkheads, pulled the tail sides together sliding past each other till the tail lined up on the straight edge as well, clamped them in place and drew the line. Now, when I applied the glue, pulled the sides in, I just needed to line up the marks and clamp the joint. All square and straight.

Image
Perfectly straight, at least in my eyes.

I'll be ready to cover the bottom of the fuse soon, so I butt joined the balsa clading flat on the building board, this way, I end up with a cross grained panel with almost invisable joints. I've always had issues when clading top and bottom sheeting (trying to butt join the panels as you install on the fuselage) the butt joints always moved on me. I'm going with cross grain as it has a better pressure strength, could have put cross braces in, but that would be adding weight. Doing my best to reduce weight from the tail area.

Image
Should be no sign of the joints when finished, love aliphatic resin, sandable.
Cheers,

Dave
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Re: Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

Here, I've epoxied the firewall in place, trimed the tailplane's tips down to the correct span and sanded the corners of the tailplane and elevator to shape. I then cut the hinge slots in the tailplane, I'll do the elevator later.

Image
Getting there.

I may close in the bottom of the fuse on the weekend, will be sanding the tailplane and fin edges to shape and glue them together ready to fit to the fuselage.

A package arrived today, $150 worth of balsa, building materials for the next six or more builds

That's where I'm up to so far.
Cheers,

Dave
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Re: Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

Closing In The Bottom.
I joined the balsa clading and the ply using the masking tape method, top down, I've found that metric ply is slightly different in thickness (larger) than imperial balsa, or was that the other way around. Anyway, the outside of the bottom joint balsa to ply is smooth, with no step.

Image
Ready to assemble.

Clamps, rubber bands and bottles of water, amazing what you can use. The Coachman, having a flat bottom from nose to tail is easy to cover, I cut the ply with a 0.5mm overhang each side and the balsa a bit more. Epoxy is used on all the fuse to ply joints, and aliphatic resin on the fuse to balsa joints, I did this all at the same time, clamped to the firewall, rubber band from the front wing dowel (dowel temporarily in place for the gluing) , another clamp near the ply/balsa joint and lastly, bottom flat on the table with full water bottles used as weights to keep pressure on the aliphatic resin glue joint.

Image
They do the job, and the square bottles don't roll off the slope either.

Almost time to fit the tail feathers, I'll trim the bottom sheeting tomorrow night and start the fitting of the tailplane, get the mounting seat square.
Cheers,

Dave
Nick M
Posts: 92
Joined: 19 Dec 2018, 20:39
Location: Camberwell london

Re: Don Dewey's Royal Coachman Build.

Post by Nick M »

Great build - reminds me of das ugli stick without the Fokker tail and scalloping on TE
User avatar
iflylilplanes
Posts: 182
Joined: 13 Mar 2018, 03:26
Location: Sydney Australia
Contact:

Re: Don Dewey's Royal Coachman Build.

Post by iflylilplanes »

As I understand, the Das Ugly Stik was styled of a model very similar to the Coachman called the Box Fli. Have a look at this link, very interesting history..... https://redirect.viglink.com/?format=go ... membership
Cheers,

Dave
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: Don Dewey's Royal Coachman Build.

Post by bluejets »

I tend to back up the formers with triangle section, especially the front where the engine bolts onto.
Post Reply