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Old Apr 17, 2013, 10:03 PM
Kansas is windy.
pburress's Avatar
Wichita, KS
Joined Jun 2003
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Peter Rake’s Farman Sport at 12”

I've been itching to try something really small with micro gear and recently acquired a new set of components for a Parkzone Night Vapor. Turns out Peter had this ideal design ready to go.

The Farman Carte Postale was a mid 1920's airplane with a distinctive wide wing. I'm hoping the stability of the parasol design and extra wing area will make for a model I can fly in the yard and street in front of my house on the calm evenings. I recently picked up an Ares brand 11”, 14 gram Tiger Moth Biplane and am really enjoying being able to step right outside and fly, weather permitting.

This will be my fourth Rake build and the plan looks familiar, with the usual true to scale outlines and an economical, easy to build design. I will try to keep it as close to plan as possible and the current plan is to cover with tissue and dope unless I find a better alternative.
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Old Apr 17, 2013, 10:16 PM
Kansas is windy.
pburress's Avatar
Wichita, KS
Joined Jun 2003
1,533 Posts
Tailfeathers

The tail feathers are your basic stick construction with lots of easy to build straight lines. I would like to point out how helpful my
Fourmost miter sander tool is with any butt-joined sticks. This is one of my most-used tools.

So far I'm using old school airplane cement. I like the working time and sandability, compared to CA.
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Old Apr 18, 2013, 03:55 AM
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Norfolk, England
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Phil,
This seems a better place to answer your queries about prop and power. From what I've read, the Vapor motor/prop puts out around 16 grams of thrust. So, that sounds pretty much like what you'll need if you keep the model very light. I have flown models of 20 - 25 grams using the stock Vapor motor/prop. If however you specifically want a smaller prop (one that doesn't make it look like a rubber power model), or think you'll come in at much over 20 grams flying weight I'd suggest you replace the vapor motor unit with a 7 mm geared unit and 4.5x3 or 5x3 GWS prop. That combo should put out around 30 grams thrust.

The plan shows 1/20 balsa, and was really intended for undoped covering and indoor flying. If you're using 1/20 balsa, be very careful how much dope you use on that wing, and what weight tissue you use. Even water shrinking lightweight Esaki will buckle 1/32 ribs, and you have an awful lot of rib to buckle on that one. If in any doubt, I'd suggest adding a rear spar and possibly making the spars bass.

Just comparing this model with my 18" span Eastbourne Monoplane, it's only about 3/4 as long as the Eastbourne, with much smaller tail surfaces but pretty much the same width fuselage. Very close to the same wing area though because although only 2/3 the span, it's 1.5 times the chord. Given the thinner wood, and a bit of care, it should be possible to get the finished weight to not much over 20 grams. The Eastbourne came in at 30.5 grams and uses 1/16 balsa and 2.5 gram wheels and has a 7 mm motor unit fitted. Maybe that gives an indication of which way you need to go.

Pete
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Old Apr 18, 2013, 08:53 AM
Kansas is windy.
pburress's Avatar
Wichita, KS
Joined Jun 2003
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Thanks Pete. I picked up a smaller diameter prop, one for the PZ UM J3 Cub. This prop has a higher pitch. I'll have them both available for the first flights. Here's the specs on the two props I have:

Vapor Prop: 140 x 45
UM J3 Prop: 100 x 60

My plan is to pre-shrink and possibly pre-dope the tissue for the Wing. I cut the ribs from 1/32 so I'll have to be extra careful to avoid warps. No worries if the wing covering is not drum-tight.
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Old Apr 19, 2013, 01:29 PM
Kansas is windy.
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Wichita, KS
Joined Jun 2003
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I've got a short fuse.

The fuselage has a solid sheet front section for strength and simplicity. The rear fuse sticks are 1/16” but I opted for 1/32” forward sheeting. To account for the thickness difference, I had to raise the second (left) fuse front sheet on the board with some scrap 1/32” pieces. This way the thickness difference between the 1/32” sheet front and the 1/16” sticks rear will not be noticable.

After the two sides were built, the formers F1 and F3 were glued to one fuse side with proper alignment ensured by the square. Next, the other fuse side was added, again with care taken to ensure square alignment. The rear crossbraces were then added.

Since the Parkzone brick was a snug fit and actually touched the fuse sides, I decided to forgo the plate and just attach it directly to the fuse sides. My Night Vapor fuselage included a nifty battery tray with velcro, so I added this to the fuselage interior using a couble of 1/6" x 1/8" sticks. Currently the battery will be accessible through the cockpit but I may change it to access from the underside if that will work better. I’ll know after the first parts trial fit.

The nose top sheeting is 1/32”.

Next comes the nose cone (cowl?)- probably the hardest part so far. I have a block of soft balsa and also some blue foam on hand. Still deciding which way I will go but I’m leaning towards carving it from foam and then glassing it using some fine fiberglass I already have on hand.
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Old Apr 19, 2013, 05:29 PM
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Norfolk, England
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Phil,
If that brick is anything like the Vapor one, it's only a couple of spots of soft glue holding it to that base. With a little care it should peel right off, saving you a gram or so.

Pete
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Old Apr 23, 2013, 10:16 PM
Kansas is windy.
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Wichita, KS
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Here's the latest progress. Turns out that I don't have a block of soft balsa on hand, and decided to make the nose cone from fiberglassed foam instead of carved balsa. I've done this before a couple of times and it's pretty darn easy. I will make the cylinders from a drinking straw. Not sure about the exhaust but I may try heat shrink tubing for that.

I am (or was, I should say) ready to sand and cover at this point.

But, I had a little setback last night while sanding the wing. A moment of clumsiness and the wing is damaged. I could repair it but I think I will just build another wing. This wing was not perfect with a little wash-in on one side as well as a hair less dihedral than called for, which is already a modest amount. I think I can make another better wing in an evening, so that's next on the list. After that it's covering and assembly.

Pete, I'm using the base on the brick for mounting so I may just leave it rather than redoing it and adding a tray.
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Old Apr 24, 2013, 04:38 AM
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Norfolk, England
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Damn, I wish I'd thought of that while assembling the u/c and pylons for my 18" Eastbourne Monoplane. I'll remember it for future models though, so much easier than gluing the rods together and to the thread, allowing that to dry and then trying not to move anything while you do the binding.
Typically, the next two I have lined up don't use conventional u/c legs, so maybe I'll have to draw up something specifically to try it out.

Pete
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Old Apr 24, 2013, 07:02 AM
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My that's a tiny bit of work, very well done.

I'll be watching through completion.

Bill
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Old Apr 26, 2013, 11:58 AM
Fly, dangit!!!
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Little Rock, AR USA
Joined Jan 2007
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I somehow missed this thread, but signing on now!

I actually have had this framed up and 1/2 covered for over a year now. I need to finish it up!

Looking forward to seeing yours complete and maybe it'll motivate me to finish mine!

J. B.
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Old Apr 26, 2013, 01:53 PM
Kansas is windy.
pburress's Avatar
Wichita, KS
Joined Jun 2003
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I have a new wing built, straighter and with more dihedral. Ready to cover. I will post pics as soon as I can.

Pete, I'm quite proud of myself for showing you a trick!

J.B., put that thing on the front burner. Sounds like you are almost done!
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Old Apr 29, 2013, 11:42 PM
Kansas is windy.
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Wichita, KS
Joined Jun 2003
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Progress

Been working on the Farman as I have time. Everything was given a light sanding and the covering started. This is some japanese tissue I had on hand. I tried some new techniques with varying success. In the past I have always shrunk with water, then doped. I was worried about warping the wing, so I pre-shrunk the wing tissue after mounting it in a frame. Then I applied it to the wing, using thinned white glue, and gave it a couple of mist coats of clear acrylic. I think I succeeded in not warping the wing but the covering is not the traditional drum-tight smooth.

The tail feathers were covered with tissue and then given a coat of thinned dope. This turned out better. The fuselage was shrunk with water and will be doped.
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Old May 14, 2013, 03:15 PM
Kansas is windy.
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I've been able to get in the odd building session and have made some progress. Covering is complete except for the fuselage bottom which I left open for now, to facilitate the pushrod installation. I will add some trim later for a sporty look.

Assembly started with the horizontal stabilizer. This was glued with white glue and carefully aligned with the fuselage centerline.

Next came the elevator pushrod. The elevator was held in neutral position with a couple of balsa strips. The wire connector at the control horn end was first bound to the pushrod. Then the pushrod/control horn was trial installed and the pushrod was marked at the servo end and cut to the proper length. Then the pushrod/control horn was installed and the control horn glued to the elevator. Finally, after connecting the receiver to ensure neutral trim, the pushrod was connected to the elevator servo. This was just a little bit fiddly.

The elevator pushrod didn’t line up with the fuselage exit slot, so I moved the pushrod further down the control horn. I'm not sure I like this though, so I may end up changing it back and moving the pushrod exit which will require uncovering that section of the fuselage side. Not a big deal since the Fuselage is not doped yet.
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Old May 14, 2013, 03:21 PM
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Cabane

The wing cabane (inner) struts were carefully measured and trimmed to the exact size. The pockets in the fuselage sides were also carefully trimmed to be even and all match in their depth. If this was a laser cut kit, this would not be necessary! The struts were glued with yellow glue and then double, triple, quadruple checked for alignment. Then the wing was glued on and I was glad to see that it turned out to be quite straight.
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Old May 14, 2013, 03:30 PM
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Undercarriage

I made a mistake in gluing the U/C struts to the fuselage by not splaying them. I decided the easiest thing to do would be to stretch them out a little bit with a length of CF rod. Not ideal but close enough, especially since ROG takeoffs will likely be the exception with this model, especially outdoors. The axle was glued and bound to the U/C struts with thread. I will probably add spacers to the axle to space the wheels out from center another ⅛” or so, for a wider, more stable stance.

I like to make lists of what's left to do when I start to get close to completion. Here’s what’s left to do:

•Install/hinge rudder and connect rudder pushrod
•Install tailskid
•Cover fuselage bottom
•Dope fuselage
•Trim/detail/markings
•Make and install windshield
•Mount Motor to firewall (how?)
•Paint Cowl
•Mount Cowl to fuselage
•Make and install dummy engine cylinders and exhaust
•Make and install wheels

At this point I'm open to suggestions on the best way to mount the motor!
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