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Chinese Cox PT-19 trainer

Old 01-06-2015, 03:20 PM
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jaymen
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Default Chinese Cox PT-19 trainer

Hello,
I bought 4 of the made in China PT-19s back in 2000, and flew one right away.
Found several things that needed attention prior to flying it:

Pushrod from bellcrank to elevator was under, instead of on top of, the bell crank causing a bind. Easy fix, remove bell crank, and install pushrod correctly

Flash on fuselage clamshell hinge for elevator caused it to bind. Sanded off flash and fixed that.

Took engine apart, lapped the back of the crankcase to remove burrs on the four threaded holes which cut the gasket, replaced case gasket and re-assembled engine. Ran engine twice to break it in, used a 5-3 grey, ran it a bit rich.

Rotated fuel tank to orient pickup to outside of the flying circle, replaced fuel line with a longer one to do this.

Balanced 6x3 nylon prop. Dead stick the prop so it comes to rest horizontally.


Use "Spider wire" Spectra fishing line to make up 42 foot lines; much lighter and less drag than Dacron lines supplied with plane.

Bent tips of gear axles up to prevent the smashed axle ends from boring into the plastic wheels.

Results: Plane does slower laps on 42 foot lines, and in calm conditions it is much better than the original version. Has good line tension, with very little line sag, wingtip weight does help when there is some wind. You can get a loop out of it if you move the pushrod to the hole on the control horn closer to the elevator. Like all Cox PT-19s, it takes very little down to dive, and a ton of up plus a prayer to pull out! The engine run is well over 3 minutes on the tank, especially after you re-orient the pick-up.

I taught my 7 year old twin sons to fly it a couple years ago, after a couple crashes they had decent control. I ran the engine a bit rich until they had the feel, mainly just to slow the plane down a bit.

The plastic wings are more flexible, but the fuselage will split in a good dig, even on grass....mine did! BTW, we found that acrylic monomer ester acts as a solvent on the fuselage and wing plastic and used it to weld the plastic back together, it works great. Available from Plastex USA.com. The paint on the pilots comes right off, I re-painted the pilots and used some polyurethane clear to protect them.
The choke tube on the sure start is a great feature, but I replaced the Snap Starter with an old style spring starter off a 1960s .049. The twin bypass cylinder adds noticeably more power as compared to my 1964 PT-19.


Like all Cox planes, you need to take a couple steps backwards when taking off to keep line tension, or you will get into trouble sooner than later. Could not quite get it inverted, but did not try too hard. This version is definitely an improvement over the earlier models, and brings back the painted pilots and windscreens that never fog! It is true that it takes an experience pilot to fly one, so you have your student stand with you in the circle, just like at the Tomorrowland Flight Circle, and hold on with them.

I must admit that I worked in customer service at Cox, doing radio and engine repairs, and so that gives me a bit of an edge when it comes to having success with Cox products.

I have a Cox made in China J3 Cub, never have flown it. Is this a good trainer?

Last edited by jaymen; 01-06-2015 at 03:31 PM.
Old 01-26-2015, 09:53 AM
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Thanks for posting this info, jaymen; I learned a few things. Do you still have the '64 PT-19? Also, does the Chinese version seem "nose-heavier" to you than domestic versions were?
Old 01-26-2015, 07:49 PM
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Tom Nied
 
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Geez, I learned how to fly controline on my friends Cox PT 19 back in 1966. Will always be a great plane to me.
Old 01-27-2015, 07:00 AM
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jaymen
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I have a few "early" Clear window PT-19s, with painted pilots. One is a very rare Kenbrite, made in Australia. Apparently, Cox made a deal with Kenbrite toys of Australia and sent them molds. The blue and yellow are slightly different shades, and Cox sent the engine assembly with wheels, bolted to the firewall, along with the boxes to Kenbrite. I think the earlier PT-19 had a more forward CG due to the weight of the metal fuel tank.
Old 01-27-2015, 12:50 PM
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Glad to hear the OP has some early versions! The reason for my question is that when I flew the Chinese rendition, pictures taken of the airplane in flight show an awful lot of "up elevator" (stabilator) in level flight attitude. I haven't flown it but once so far and am looking at ways to move the CG back without adding weight. My thoughts being that perhaps the airplane will be more responsive. Another question - could you do me a favor and compare the early versions with the Chinese version side by side. I'd like to know if the stab has a greater range of travel/throw in the up direction on the early ones? Since you're performing loops with the Chinese one, it may be a moot point - but I'd still like to know...

BTW, I was amazed to hear what was said about another Cox airplane in the original post. I didn't know there were others besides the PT-19 being made elsewhere. Is the made in China, J-3 Cub possibly based on the old bush plane that - at one time - came with wheels, skis, and floats?

Sorry for all the questions but I value the advice from someone who worked at Cox and has knowledge of Tomorrowland.

Hoping the pic shows the amount of UP elevator I'm concerned about to maintain level flight.
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Old 01-30-2015, 02:32 AM
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Kipp Louis
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My first RC airplane was the Cox P-40 5th version that my dad handed to me, nearly fainted to see this trainer. it had one of the best handling that I had ever seen. I had the Mustang, Corsair, Stuka, and the P-40. love those also.
Old 01-30-2015, 05:35 PM
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I can't understand why other Cox airplanes aside from the PT-19 seem to get a bad rap. I got my start in aeromodelling with Cox and Testors products and developed the skill to fly - not crash(!) - at least those that I owned during my teen years. I never tried to fly inverted however, and I don't know if sustained inverted flight is even possible with the undercambered wing Cox airplanes. It was the neighbor kid that performed the only successful loop I had witnessed at that time with his own reverse color, PT-19. I don't know if I ever saw the P-40 fly but remember it was equipped with rubber tires and if it glided as well as the Stuka, believe it was probably capable of quiet, smooth as glass, landings when flown over blacktop. Yeah, the rubber tires were probably heavier and cost more to manufacture, but they were so much classier than plastic equivalents... IIRC, the P-40 was equipped with a complete Babe Bee including metal tank in all the airplane's versions?

Last edited by H5606; 02-01-2015 at 01:33 PM.
Old 02-01-2015, 05:36 AM
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What weight "Spiderwire" Spectra fishing line should be used and would you simply tie a square knot at the bellcrank? Thanks for any advice in this regard.

Last edited by H5606; 02-01-2015 at 01:36 PM.
Old 02-03-2015, 08:50 PM
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Bill Adair
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Ten pound test would work, but Twenty pound test is easier to work with.

Spectra fishing line requires special knots, and we have been using the Palomar knot. Note that the Internet video for tying this knot is for attaching a fish hook, but it also works for the small (half-A) slider line clips that are available. Tie it to the closed line clip like you would a hook eye, and pull it snug.

Do NOT use CA to hold the knot, as it will create a hard CA stress point that will eventually break strands and fail. Tie the knot dry, are lubed with water or spit to pull it tight.

The only other failure we have seen was when a club member shortened a set of lines, and the knot was tied without cleaning the Castor oil fuel contamination!

Bill
Old 02-05-2015, 10:03 AM
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Okay, thanks.

Beginning to think I'm using poor forum etiquette; I'll keep quiet.

Last edited by H5606; 02-06-2015 at 11:02 AM. Reason: Attempt to be humble :-)
Old 02-09-2015, 11:40 PM
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5606,
Most people are polarized about their Cox experience. Trauma, or boyhood experience. Trauma were usually people that can't read directions, didn't have help, or don't have much patience and stick to-itivness!
I flew them all, but only a few were mine. Tee Dees were hard to start for me but I ran them too compressed as a child and was only successful when having adults help at contests as they were all on 1/2A Proto and Profile Proto models. The rest were easy and even figured out how to run wen macs and some others. Cox red can Racing Fuel and fibreglass props made any model better, still today.
I still have my 1965 PT-19, Wen Mac Day Fighter, and a few I picked up later. They all are flyable but I haven't done it in years. Should video them, it'd be fun to get them out.
Chris...
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Old 02-16-2016, 01:21 PM
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jaymen
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A bit late on my response, but we have found the thrust angle you set the engine at does determine the elevator trim. At the "stunt" setting, you do not need as much up elevator when compared to the beginner thrust position. PT-19s seem to fly at a pretty high angle of attack due to the decalage/incidence relationship between the wing and stab, so it's normal to see what your picture shows. Most Cox plastic planes were similar in that they were best at doing gentle climbs and dives, nothing really sudden or radical, and you needed to initiate a climb well in advance to avoid a "ground swell". The all balsa slab wing trainers by Guillows, Goldberg, and Sterling were far better flyers and responded much better, in fact it was not until I had built and flown a 1/2A balsa plane that I was able to sucessfully fly a plastic Cox plane. With a teacher however, most kids can gain control of a PT-19 with a few minutes of flight training on a calm day.

All of the PT-19s with a seperate plastic fuel tanks have a a further aft CG because the early metal tank Baby Bee was heavier. Have not really noticed much difference in the way they fly due to that, because the biggest difference is with the lighter lines, and the wing tip weight adding more control feel at the handle.
Old 02-20-2016, 08:17 PM
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I love zombie threads - coming back to life.
Picking up some good info for the as-yet unscheduled 2016 IPT19FIIYGID.

Maybe we have the photo for the virtual poster from this thread, love the photo above.
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Old 02-25-2016, 09:34 AM
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Originally Posted by jaymen View Post
A bit late on my response, but we have found the thrust angle you set the engine at does determine the elevator trim. At the "stunt" setting, you do not need as much up elevator when compared to the beginner thrust position. PT-19s seem to fly at a pretty high angle of attack due to the decalage/incidence relationship between the wing and stab, so it's normal to see what your picture shows. Most Cox plastic planes were similar in that they were best at doing gentle climbs and dives, nothing really sudden or radical, and you needed to initiate a climb well in advance to avoid a "ground swell". The all balsa slab wing trainers by Guillows, Goldberg, and Sterling were far better flyers and responded much better, in fact it was not until I had built and flown a 1/2A balsa plane that I was able to sucessfully fly a plastic Cox plane. With a teacher however, most kids can gain control of a PT-19 with a few minutes of flight training on a calm day.

All of the PT-19s with a seperate plastic fuel tanks have a a further aft CG because the early metal tank Baby Bee was heavier. Have not really noticed much difference in the way they fly due to that, because the biggest difference is with the lighter lines, and the wing tip weight adding more control feel at the handle.
I think I had the engine set at the "stunt" setting (no down thrust) when I flew it; as best I remember, the airplane as seen in the picture was in straight and level flight at the time the picture was taken yet it shows what I still consider a lot of "up" deflection.

I agree that most of the Cox plastic airplanes were at their best doing gentle climbs, dives, and flying straight and level. However, a few I remember as carrying terrific momentum and line tension through to touch-down with a realistic roll-out (on an asphalt surface) after the engine quit unlike the sheet balsa profiles I had. If you needed to, whipping was an option to set it down where you wanted. The Stuka, Miss America, Corsair, Super Sport, and Rivets come to mind. The PT-19 for some reason didn't seem to glide well though. The 1/2A balsa airplanes I had, a Sterling profile Spitfire, a Scientific Piper something or other and a couple Ringmaster bipes were much quicker responding under power but energy dissipated quickly when the engine quit making the pilot work quickly to maintain line tension and flare for a less than satisfying landing. Bipes having lots of drag is probably a big factor here. Granted, the Ringmaster bipe was the only airplane I was ever able to successfully loop back in those days.

In trying to analyze it myself, wondering if its all a function of wing loading, landing gear location and drag effects that influence the differences in landing qualities.

Last edited by H5606; 02-25-2016 at 09:42 AM.
Old 02-25-2016, 06:39 PM
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I had a Baby Ringmaster that I built with a Cox Golden Bee, and it flew pretty good. Wing overs, loops, lazy eights, inverted flight all possible. But it really hauled donkey. Had to really keep up with it on 35 foot dacron lines.

Now my memories of flying my friends PT 19, it was a pretty much a dog. But I did learn how to fly Controline on it.

Last edited by Tom Nied; 02-27-2016 at 03:45 PM. Reason: changed a word
Old 02-27-2016, 08:46 AM
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My first flight was with my brothers Testors P51. Then My Dad helped be build a Baby Ringmaster
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Old 02-27-2016, 03:53 PM
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Baby Ringmaster with a Cox .049 is a good combination. Covered mine with MonoKote, patinted the fuse & tail. The weak spot is right behind the motor mount.
Old 02-28-2016, 06:37 AM
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Looping was a formidable, nearly unobtainable, big deal for us kids at the time sort of like breaking the sound barrier was to the X-pilots of the late '40s. When the neighbor kid performed the first successful loop with his PT-19, us bystanders were hooting, hollering, and jumping up and down like the greatest event had ever taken place (well, okay, maybe I was the only bystander...). My Baby Ringmaster never saw completion - the neighbor kid attempted a second loop and splattered his PT-19 into the asphalt. As I remember, the wing was the only thing that didn't survive. I gave him the framed up wing from the Baby Ringmaster and he covered it with typing paper and Testors Blue dope. He used it as a replacement wing for his PT-19 - it was really ugly but it flew again.
Old 02-28-2016, 12:55 PM
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Yeah H5606, that's a pretty accurate description of what I saw as a kid, as far as looping a Cox PT 19.
Old 11-18-2021, 02:34 PM
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Default New PT-19 prices are skyrocketing

Wow, has anybody seen the prices the NIB/NOS Chinese "you fly" PT-19 trainers are bringing? $400 is what I have seen on eBay.

I guess if you adjust for inflation it partially explains it but back in 1995 they sold for $40. Makes me wish I has bought a dozen or more and stashed them away. Occasionally, if you are lucky, you will find them on a Buy-it-now for under $200, but that is the exception, not the rule.
Old 11-18-2021, 08:32 PM
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I've always thought that a Balsa version would be possible with a little research and work. But I think it could be done. Remember how you set the motor for training or stunting? I only flew my friends, but that was the plane I learned how to fly Controline.

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