Ordered a 1/2A Skyray kit

I have to say it does look nice with the gear you had on it. I like the stance. Having built many Skyray's over the years, I knew the turning was going to be somewhat compromised. The Skyray is intentionally designed a bit on the tail heavy side so I thought this would've balanced things out a bit. As you mentioned though there's just drag all over and the speed and maneuverability falls off. It still looks great and I commend you on a nice job there.

Thanks to Eric, and Ken for their comments.

roddie wrote:Very cool mod there man!! I'd really be interested to see the detailing (close-up images) on the "drop-off gear". The fact that it functioned well for you.. is what interests me; as I've had a long-time interest/need-for a control-line take-off dolly for "1/2A proto-speed" models, but haven't been able to source any information on fabrication.

Secondary.......... the "NEST" control-line guys here in my neck of the woods, have a circle-mowing system that utilizes a small 20-22" self-propelled lawn-mower with a 40-foot tether connected to a central-post which automatically mows a 80" diameter C/L flight-circle in short-order.

I "do" like your 1/2A drop-off main-gear though. Please supply photos/drawings of your design. Thanks!!!

It's pretty basic.  It's a proof of concept prototype, so some of the dimensions could be adjusted. The U shaped piece could be shorter, as could the legs. I made this before I read Ken Cook's post on soldering and binding his landing gear. I just soldered the legs to the U piece with silver solder. I doubt they would hold up to landing shocks, but they don't have to. My soldering job isn't too pretty, but the goal was to see if the idea would work. Appearance was low on the priority list.

Materials were a 4' long 1/8" diameter steel rod, and two pairs of 1" removable pin hinges.



I pulled the pins on the hinges, and used the halves with the single pin boss. I drilled out the pin bosses to 1/8" as the pins were smaller than that. The hinges are pretty soft steel. You could probably open them up by driving a 1/8" or 5/32" pin punch through the bosses.

The holes in the hinges matched the engine backplate holes close enough that I didn't have to do anything with them.

I sandwiched the hinges between the backplate and the engine mount.



The distance between the pin bosses after mounting was 1-3/8" center to center.
I got a piece of steel from work which measured 1-1/4 x 2 x 2-1/2". I ground a rough radius on the two edges along the 1-1/4" width.
I bent the wire around the steel form so the the ends came out 1-3/8" apart, and the legs were 2 inches long.



Then I started test fitting the U into the pin bosses. I had to tweak the bends, and file the wires until the U slid into the bosses and dropped out easily.
The legs are 6" long pieces with 45 degree bends 1" in from each end.

I soldered the legs to the U with everything clamped to a steel plate so nothing moved while soldering. I used a  propane torch to heat the joint, and some flux that I had laying around.  The upper ends of the legs are 1/2" below the ends of the U.






Hope that covers it well enough.

I attempted to fly the Skyray again tonight, but it was hot, humid, buggy, and the engine didn't want to run. So I gave up and went home. Oh well. Try again tomorrow, maybe.

Happy Independence Day to everyone

Awesome idea. I never would have thought of that. I'll file it away for future use.

The Thief Mark

TL,
I noticed you switched back to the wedge tank. Have you figured out why it didn't work before the clumk tank?
How long is a typical flight on wedge? What size wedge?

Thanks

944_Jim wrote:TL,
I noticed you switched back to the wedge tank. Have you figured out why it didn't work before the clumk tank?
How long is a typical flight on wedge? What size wedge?

Thanks

I really don't know why the wedge tank didn't work the first time around. It may have been the needle valve moving and I didn't catch it at first. My other thought is that the engine wasn't broken in and it was getting tight halfway through the run. The wedge seems to work fine now.

It's a 3/8 ounce tank. I haven't timed a run, but I'd estimate at least two minutes

Got a chance to fly the Skyray tonight. Had nearly perfect conditions. I only got two flights in though because that long brass needle valve broke off right at the end of the threads.
The brass got brittle from the vibration, I guess. Man this stuff gets frustrating.

Now I have to figure out how to get the remains of the needle out of the spray bar. Is there a short needle with the same threads?

I tried it on 44' lines tonight. That might be a little long. Not much line tension. If there had been much of a breeze, I think I might have had problems. Have to go back to the 38' lines I was using.

Anyway, I got a few good shots of the takeoff gear dropping off. At least that worked.

Cox International has a shorter needle:

coxengines.ca - Cox .049 Needle Valve Brass Short



Sometimes you can take something reasonably pointed like a jewelers screwdriver or awl and carefully coax the stub out. Brass is softer compared with steel. If no luck, with care, you might patiently be able to scribe a slot on the top with a sharp pointed tool. Then use a small or jewelers screwdriver in the slot.

If no luck, Cox International also has backs for a nominal fee.

Sometimes (but not always) locating the back so needle points to the side instead of vertical helps to prevent dinging the needle on a nose over, crash or inverted landing.

Good pics. TL , you probably want get the broken one out i would apt. for one these https://coxengines.ca/cox-.049-.051-backplate-white.html and either a killer bee needle if the thread pitch is correct or a short needle like George said https://coxengines.ca/cox-.049-needle-valve-killer-bee.html Most people have said the Alum. has less issues with the vibration https://coxengines.ca/1968-cox-.049-needle-valve-aluminum-oem.html Hope you get R squared away soon .

Eric, you brought up an interesting point. OP would need to verify whether his back uses the finer thread needle of the Killer Bees and earlier red postage stamp RTF engines of the 1960's, or the coarser thread needles of the horseshoe back engines. Since his engine uses a black horseshoe back, I'm thinking it probably uses the coarser needle but I could be wrong.

Thanks to getback and GallopingGhostler for the needle valve info.

Cox International lists the thread size of the short needle as 2-80. A #2 size thread has a major diameter of .086". My broken needle measures .085" diameter over the threads. My thread pitch guage doesn't have 80 tpi on it, but I'm guessing that my needle is a 2-80. So, I have a short needle on order from Cox International.



I got the broken piece out by poking a pin into the fuel inlet nipple, and pushing the needle out the other end.

In the meantime, if I get good flying weather, I'll use the engine from the PT-19.
I looked at the needle in the PT-19 engine and the threads looked much finer, so I can't just swap needles.

I took the engine out of the PT-19 yesterday, and put it on the Skyray. Went back to the flying field in the evening, and got three good flights in before it got too dark.



That old .049 runs great. It also runs nearly twice as long as the other engine, on a tank of fuel. Don't know what's up with that.

I shortened up the lines to 39 feet tonight. We'll see how she handles at that length. Hopefully soon.

Got my new short needle today from Cox International. And a new spinner to replace the one that flew off last year.

Did a test run, now I need some airtime. Winter is coming.

Got a chance to fly the Skyray a couple of days ago. Got three flights in before dark. All fairly problem free. Lost the spinner again . Those things come off pretty easy, and disappear.

The 39 foot lines seemed to work ok. I really like how the plane glides after the engine quits.

Had a nice evening, so I decided to fly the Skyray again. On the last flight, I did something I've never done before.

                                                            I LOOPED IT!!

It was a yank and pray move, no skill involved, but it worked. Unfortunately, the wife didn't know I was going to do it, and missed it with the video camera. Just got a partial shot of the plane coming out of the loop.



A few more pics.







Something strange happened on the second flight. As soon as the plane got off the ground, it was out of control. It went straight up and the lines went slack. I was going through some moves trying to get it under control, but it eventually came back down into some tall grass. If I had been flying over a hard surface, the plane would have been destroyed.

I have a suspicion that I might have taken too much nose weight off of it. Anyway, it was a good evening for flying, and the plane is still in one piece.

If nose weight is needed, a possible compromise may be to go with a single wheel landing gear. Use a lightweight parkflyer spoked wheel that is reasonably streamlined so it won't be so draggy. Just a thought.

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GallopingGhostler wrote:If nose weight is needed, a possible compromise may be to go with a single wheel landing gear. Use a lightweight parkflyer spoked wheel that is reasonably streamlined so it won't be so draggy. Just a thought.

Thanks for the suggestion GG. I'm trying to avoid using landing gear, as it just catches in the grass and flips the plane on landing. I decided to try this:



Each nut weighs about .16 ounce, and I can add or subtract weight in small increments this way.
I haven't flown the plane yet with the weights on it, so I don't know how much I'll need.

If nothing else, it's now clear what the plane's gender is.

Splitting my sides laughing!

NUTS, that is funny!! I thought the punch line would have been “ it’s here looking for a Señorita! “

Obviously! you put a COX engine on it........grin