New 1/2A combat build

Now thats awesome .... nicely done!

Hi Ken, That looks really nice. It is interesting you will cover it in mylar but I think there is a typing error as 0.5mm seems rather thick to me. I have a NAJ Mini 92 as a restoration project. It's a 1992 combat plane for the then existing 1,5cc class. The wing is covered with mylar of 25g / m² and is only 0.1mm thick when measured with a vernier. Is mylar easily available in rolls and at an affordable price?. I couldn't find any when surfing the net so I bought Oralight. However, Oralight is a bit heavier at 36g / m².

Lieven

Lieven, your correct. The measurement isn't in mm. It just says m. They don't specify exactly what this is in terms of the m but this stuff is very expensive. I buy it from a fellow flyer. He purchases large amounts of this and sells it amongst flyers from coast to coast. A 12" roll and I have no idea how much is on a roll is approx $300. This material is as thin as packing tape and has adhesive already on it. I never seen anything stick to foam like this stuff. If you were looking for a Mylar like material at an affordable cost, Phil Cartier provides SLC covering. Phil's covering is chemically treated to take paint and also adhesive. When Phil builds a plane, he covers the root of the wing panels first with this covering, he then glues the panels together film to film. If the plane suffers a mid air, the film is like a sacrificial layer between the foam and the end result is a bit of torn up covering allowing a very easy repair. Ken

From Phil's site: http://home.earthlink.net/~philcartier/webcat/catalog.html        COV-1


Sample


10 ft.
6 oz. shipping is included in price


$6.00

COV-2


Roll


100 ft.
l lb 5 oz.


$35.00

COV-3


Large Roll


24+ lb(~3500ft)
28 lb.


$650

My busy work schedule has had me out of the modelling scene for several months now. The plane is now covered and painted ready to go with the exception of a few loose ends. While that hasn't changed too much, I'm fortunate to enjoy the 3 day weekend. This will entail going flying and burning up some fuel. I have a lot to get in . I completed the "Phantom". This will see it's first flight and I can't wait. I have a few TD's ready for action one being a KK TD which I was fortunate to receive from a friend. The KK version has a ball checked backplate which I will be removing and replacing with a standard Cox unit. This is going to be run on bladder pressure not crank pressure. The nose was painted with the few remaining drops of yellow Nelson Hobby paints I had left. Man I love the stuff and it just looks to darn good not to use.

Hi Ken, That's really slick! Is the spar made from balsa or basswood? Very cool how it all jigs together! Did you run the ribs (stacked) through a table-saw to establish the spar-slots? How about the slotting of the spar itself? All the parts seem to fit together very nicely!

I have a few packages of those pushrod-keepers. I always wondered how safe they were.. I guess if they're safe enough for your combat models.. then they're safe enough!

I actually use one on my little self-designed "Rodbat"..




Glad you got around to finishing the Phantom! Hope it fly's well.

Roddie, all ribs were square and during that opportunity, I cut the slot for the spars on a table saw. I just use a thin kerf plywood blade.  Afterwards, all ribs shaped via bandsaw and sanded on a disc sander. There was enough for 3 models. Rear slots were also cut on bandsaw and cleaned up with a Perma grit sanding file.The spar is balsa with a 1/64" ply shear web in the middle. Nothing fancy really, just simple construction. I haven't weighed the model, I was hoping to fly on 42' lines but I think due to it's size 35' lines is a must. It was a fun project with the exception of bellcrank mounting which was a bit problematic. I barely had enough swing radius and clearance. As for the keepers. I use them frequently but keep in mind, I only use them as a retainer, not as something to rely on. My pushrod without keeper can't come out of the horn even if the keeper was not installed. To properly install them, you need to screw them on exactly at the point the pushrod takes a 90. This alleviates bending of the coil and they go quite easily onto the rod. I don't like the use of a clevis, I had too many failures not to mention threads failing in the clevis and or the pushrod itself. Ken

Ken ...very cool bird.... any chance you have files of the plan, parts templates, or such that a guy could copy it?

Did you grade for very light wood or just use what you had?

I already have a few light tube bladder compartments made up that are a tad over 1" dia...doubt a slight hump in the wing would be a big issue as I just fun fly anyway

Fred, Dawson sent me the majority of the parts. Unfortunately, several parts were damaged in shipping. The box was really mangled when it arrived and I expected the worse. I have quite a collection of balsa and I don't go crazy finding the correct piece as most of it is quite light.I have my wood in a bin selected by weight in grams and go from there. I use all of the super light stuff for stunters not for combat. The problem arrives when trying to locate a piece strong enough such as elevators or trailing edges. Fortunately, the trailing edge was still intact. I had to remake a lot of the parts due to damage. The fellow responsible for this design has experienced a lot of health issues over the past few years. I don't expect to see him making an outing in the future. I was able to fly him in Huntersville a few years back. At dinner one evening we exchanged a lot of ideas and he had sent me the plans in a file. I can't locate this file. I haven't gone crazy trying to do so, but I have a lot of goodies in storage with that particular file one being Dan Rutherford's plans for the "Dirty Beaver" which is also TD powered. The Dirty Beaver can be designed twin boom or single boom. I can only imagine how he stumbled upon that name. Dirty beaver plans are available on Ebay. I like the older designs and enjoy trying them. It's really cool to see the TD at work. Ken

Ken, Thanks much for the info on this model. It's really an honor that you've built it. Mr. Foster will be proud! I hope you're able to share your experience of his design with him.

That is a very cool looking plane Ken , I bet you do have a betta. base of builds awaiting attention since your around some prestige people up your way. Its nice to see you getting in to Cox engines more even though they don't compare to what your usually running . Its a shame the parts got there in a destroyed manner I understand the filling of just seeing it and wondering if anything is useable or not left in the crushed boxes?!? I really like the way the elev. is employed into the TE gives it a nice slick appearance ! Eric

Ken

I think I can copy it from the photos if you can tell me the length of one rib, the height of the center spar and thickness, and the thickness of the TE/Elevator

I really do like seeing photos of members builds on this forum and this is no exception.

I am always amazed how just a small area of color can make a model stand out and a transparent covering shows of the build.

When I look at this one - I have to ask - Was the fitting of the bellcrank trial and error?

The push rod to the elevator goes through the tiniest of holes. The model I am building at the moment the slot for the pushrod gets larger and larger even though I am building it to plan!

I also notice there is a reddish brown on the sheeting near the engine mount.

Please tell me that it is a blood stain! My models get covered in them! I don't want to be the only one.

Ian, let me explain my bellcrank. Sig bellcranks are pretty much identical. This one looks and to me appeared to be a Sig bellcrank. It's not and it's actually almost 3/8" larger. Essentially now this is making my controls much slower. I also keep my control horn as close to the center line of pivot to even further reduce elevator throw and slow the controls down. So to answer your question, yes it took a bit of fiddling to get distance off of the center rib to my liking. This entailed a bit of wood removal in the ribs as to not catch on the leadouts etc. The reddish brown you see is 1/64th ply. I sanded through the top birch layer exposing the glue. I do this a lot and I intentionally do it especially on doublers, and pads around my elevator control horns. This model didn't have the pads yet because I chose to cover the elevator with Monokote and I made a little pad covered with the same iron on covering.

Did this plane ever get finished and flown?


I would still like the dimensions for a winter build

Indeed it has been flown. I had to shorten the control horn to speed up elevator throw. It flew excellent actually. I flew it on 35' lines not the standard 42' for 1/2A combat. It probably wouldn't be real happy on 42's using the TD. I have some VA's that would've suited this plane with some more power but the TD did ok. The plane certainly has terrific capability. Fred, I can't offer more than wingspan and a few others like nacelle length. The plane is built and covered. I can give my best guess on wing thickness at the high point.

I like it. Until you mentioned the shear webs, at first I thought you had just cut slots half way into the ribs, and matching slots into a long one piece vertical flat strip, and then capped it with balsa sticks to make an I-beam. Kind of like Brodak's Baby Flite Streak if I remember right. I think it had over and under slots to accept the ribs. That fat center rib arrangement looks like it'll take a vertical landing pretty well. Hope you don't do that too much Lol. I bought some Great Planes white ball links today and it looks like you might have one of those on your bellcrank, but I couldn't blow the picture up enough to be sure.
Thanks for showing us.
Rusty

Ken

I would like rib chord length..you said a 1" rocket tube is used, so I can guess at rib shape and high point with that info

Approximate width of the horizontal spar inset into the ribs before the TE....looks like 1" x 1/8th" but could be 3/4" wide... hard to gauge in photo

If I

Ken Cook wrote:Indeed it has been flown. I had to shorten the control horn to speed up elevator throw. It flew excellent actually. I flew it on 35' lines not the standard 42' for 1/2A combat. It probably wouldn't be real happy on 42's using the TD.  I have some VA's that would've suited this plane with some more power but the TD did ok. The plane certainly has terrific capability. Fred, I can't offer more than wingspan and a few others like nacelle length. The plane is built and covered. I can give my best guess on wing thickness at the high point.

All you have to do is wrap a length of solder around the wing to get a nice airfoil template. Do it carefully and it will be very accurate, been using the method since my Father showed me approximately 150 yrs ago