Cox PT-19 Trainer.

OH Boy ~! That's a Nice one ! Nice little piece of history to go with it , see its all cleaned up now you did a good job on it and getting the decals layed back down My question is what are you going to do with it ? I know you can't do round D rounds . It is a nice clean piece of Cox history !

Very nice PT-19 Mauricio!!!…. Wonderful to have a piece of early Cox history…. Will you try and fly it?…. Control line is its own form of fun

Thanks friends for the messages!
Jorge: I found this model by chance, it is from a seller, he is not a friend, so I bought it.
Eric: so you remember that I get very dizzy if I do a circular flight! Yes, friend, it's true, the last time I tried it, a few years ago, I got discouraged, I finished the flight with a balsa board model and a Cox .049, it was a Zero...well...I didn't feel well the rest of the day....but I may try the Cox PT-19, perhaps lengthening the range a little. Threads, I think it could fly with a radius of 10 meters? Or could it go a little further?
Roberto and Eric, the reality is that I bought it because I always saw it on the cover of LUPIN magazine, when I was about 10/12/years old, this model is history for me, it is at the same time part of the story by Cox and all that makes me want to enjoy looking at it on my shelf... it makes me happy.
This model is really healthy, I think it has a factory error...I think they were never able to fly it and it is because the elevator control is too long, the elevator is always at an angle.
The control rod should be 17 cm and this one is 17.5 cm....I think there is an error there...I will share photos and you will tell me...
Can anyone have the box this model came in? I need to print something for it! Thanks in advance!

Let's get to work...here I come:







Rocker stem repair:

Yea i should bee level when in neutral at bell crank ,good repair on the stem to , 35' would bee the ideal length for the control lines .

getback wrote:Yea i should bee level when in neutral at bell crank ,good repair on the stem to , 35' would bee the ideal length for the control lines .

Thanks Eric!...please tell me what expression those 35 are in? Are they foot?

35 feet is equal to 10,668 meters

Nice repair and calibration of controls on your PT-19 Trainer Mauricio….I think the PT-19 was probably one of the most successful to fly that Cox had…. Also there are many interesting threads here on CEF on PT-19’s…. A very well thought of design from Cox!

rdw777 wrote:
Perhaps the easiest way to do half-A C/L is to fabricate a remote " 'round the pole" system with a stationary location outside the circle.

One with good imagination and practical skills could easily fabricate such. This overcomes the dizzying problem by placing the pilot in a stationary location.

Sterling called theirs Auto-Magic...but it was a handle on a pole running the bellcrank. It still needs some tweaking to place the model in the air at speed, and slowly applying "up" as the model sank during power-off landing.

What you describe could be called RTP-CL/RC. That is, Round-the-Pole Control Line over Radio Control. Phew...what a mouthful! Any body care to come up with a better name? If not, I think I'll patent this one.
I envision this one as two lines between plane and control head. The control head would contain double-arm servo, with receiver and battery on the pole.
This is minimal.weight on the plane, and would allow for traditional CL flying.

I guess if the RC servo ran the elevator directly (on board vs in place of two lines and "handle" on the pole) with only one line to the plane ala traditional RTP, then this could be called RTP-RC...which is much more manageable to say. However, now the weight is carried on board as in single channel RC. Besides the extra weight, this would be purpose-built with no two line conversion possible.

Somewhere on the forum is a handle/stick that operates the bellcrank via a cable from the outside of the circle. I seem to think Mauricio was involved in presenting it. This one is also a method for conversion, allowing any plane to be flown in the traditional CL fashion. (Do I remember this correctly?)

Cox placed a rubber cone in some of his airplane models, this is to cushion a blow in case of crashing. In this way the impact would be largely absorbed by the cone, thus preventing breakage of the engine or other part of the model airplane.
The cone of my PT-19 is 40 years old and hardened, completely losing its function.
Using a silicone plug I intend to achieve a similar cone and with its shock-absorbing function.

Thats going to be interesting Mauricio, silicone isn't lathe friendly. Eager to see how you are going to do it. I think Matt and Bernie sells these.

Wen Mac makes a version of the pole mount remote C/L control.

Here's mine.



Some dreamers on ebay are asking $150.00 plus. I paid $39.95 for mine with free shipping.

Roberto, if you watch the video, you can see that it has already been achieved. Silicone can be turned, two points:
1) the correct speed of rotation.
2) the tool perfectly sharpened.

The flight control is interesting!...maybe I can manufacture it...I just should know its parts.

MauricioB wrote:Roberto, if you watch the video, you can see that it has already been achieved. Silicone can be turned, two points:
1) the correct speed of rotation.
2) the tool perfectly sharpened.

The flight control is interesting!...maybe I can manufacture it...I just should know its parts.

I just watched the video Mauricio, I'm amazed that you achieved such positive results, you must have a very sharp cutter and a delicate touch. Did you have to experiment with the speeds?

The WM control is very nice, but I would think that one could be fashioned with a stick, a pivot, and some string. I think there is someone in the UK that did just that. I have been thinking about doing it saving me from falling down after a few rotations. Been there.

Bob

Engine running test with a cone made of turned silicone, starting from a beverage container cap.
Original Cox 6 x 2 propeller.
Engine clockwise rotation.
Fuel: R:20%/N:25%/rest methanol.

Roberto: the rotation speed must be high, the tool must be very sharp and it must advance slowly, that is, the revolutions are fast, the tool advance is slow.

MauricioB wrote:

getback wrote:Yea i should bee level when in neutral at bell crank ,good repair on the stem to , 35' would bee the ideal length for the control lines .

Thanks Eric!...please tell me what expression those 35 are in? Are they foot?

35 feet is equal to 10,668 meters

Yes this is correct " is inches and ' is foot in USA . Man you can turn about anything on the Lathe you are mastering it my friend ! The cone looks great . This would bee good if you can get the outside the circle C/L fling and can di it with out getting Dizzy .
The engine sounds New, runs good

MauricioB wrote:please tell me what expression those 35 are in? Are they foot? 35 feet is equal to 10,668 meters

¡Eso es correcto! That is correct!

(Para mis amigos estadounidenses, en algunos países usan la coma en vez del punto para la parte fraccionaria).
(For my American friends, in some countries they use the comma instead of the point for the fractional part.)

Mauricio, tu proyecto es muy bien. Your project is very good. Disfruté mirando a tu vídeo. I enjoyed watching your video.

Thank you Eric and Jorge for confirming the measurements of the flight lines.

Have you observed that this model has the engine with its propeller that rotates clockwise, it does not have ballast in the right wing, can someone tell me which of the physical techniques is best for flight?
I also have the blue and yellow PT-19, but this one has the motor that rotates the propeller counterclockwise and a counterweight on the right wing...anything to comment on this? thank you!

Hi Mauricio, A "left-hand" propeller will cause the model to "torque-roll" counter-clockwise.. which is beneficial for a control-line airplane. When flying a conventional (counter-clockwise) flight path; this force will roll the model away from center-circle.. lessening the need for outboard wing-tip weight.

Because the majority of people (in general) are right-handed; is likely the reason why control-line models are flown in a counter-clockwise rotation. Since reed-valve engines can run in either direction; it's advantageous to run left-hand propellers. Conversely; rotary-valve model engines with their right-hand (only) propellers are torque-rolling the airplane "inwards". If line-tension is compromised.. there is less force to prevent the model from rolling inner-circle. Outboard wing-tip weight helps to counteract this force.