Control Lines For all you fly-by-wire fanatics!

International Cox PT-19 Fly It If You Got It Day

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Old 09-25-2017, 03:55 PM
  #26
H5606
 
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Had intentions to fly mine on the Fly It If You Got It Day but...

CD'd an R/C club fun-fly on the 23rd and brought along the turn of the century, "Chox" PT-19 - was too worn out to fly it, so brought it home.

On Sunday evening though, after a couple beers, had a real strong urge to fly the thing. Checked for clearance in the backyard and marked out a reference point towards the center, trying to take advantage of the most tangent line on the concrete walkway to get the longest possible surface for a runway.

After a trick learned from my last outing with experienced help: blowing the reed loose from 3 years of inactivity with a fuel bulb and thumb over vent/overflow, I got the airplane started before enlisting the assistance from my wonderful wife - shut the engine down with the needle and opened it too far.

For the vid, cut out a minute and a half of flooded engine start attempts before Maggie (the one wearing the fur coat) wispered some advice and put me back on track to get it running. Got airborne in less than quarter circle! Blame the less than graceful arrival on the suspected restricted travel of the elevator cut-out in the rudder...

Realize it may not count but wanted to share.

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Old 09-25-2017, 05:17 PM
  #27
BrightGarden
 
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Default First time flying PT-19s at all, 1st time IFIIYGI event

Got 2 Flights in, 2 different PT-19s of different vintage. Always leave things to the last minute, when you have a whole year to get ready, right? It took Sat afternoon to find a couple of engines that would run, then a run-in with the bellcrank/pushrod setup in the newer of the two really held me up Sunday. Fitted the flights around familial obligations, but got the flights in to get on the boards.
26 circuits on the older of the two, on Sun a.m. 34 circuits just as the day ended with the newer of the two.
Already looking forward to IFIIYGI 2018, is anyone else?
I'm thinking Fri-Sat-Sun 21-22-23 Sept, 2018???

I tried to get video from my phone but in the sun on a 93F day, my phone shut down due to heat?
Still pics will have to do. My dear 89 year old dad operating as flight engineer.
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Old 10-01-2017, 03:31 PM
  #28
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BrightGarden, your first pic shows early gen and suspected late gen (Chinese) version side-by-side from what I gather.

Would appreciate close-ups of horizontal stabilator carry-through on the yellow fuselage, blue wing version in background.

Re your first pic: down elevator on the early gen sitting static looks way down indicating more travel; suspect my Chinese made PT-19 has restricted stabilator movement due to webbing aft of pivot carry-through, cut-out in vertical stab/rudder, and relief in fuse acting as a mechanical stop for "up/down elevator" even though pushrod is on hole closest to pivot point of horn... Believe your second pic is a Chinese made version like mine and prefer that blue vertical stab like my long-gone, original from '70's had.

Thinking changes were made to this latest version restricting movement to prevent over-control for new pilots. Considering opening up cut-out in vertical stab/rudder to increase available "up" stabilator travel.

Posting pictures of mine for reference.
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Last edited by H5606; 10-01-2017 at 03:44 PM.
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Old 10-01-2017, 05:46 PM
  #29
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Good questions - it forced me to clean the planes up after last weekend and get my head back into what was going on.
Both of mine were made in the US - I will post pics of the boxes here to show where they came from.
The oldie had 2x the throw, but not to the limits set by the void in the vert stabilizer/rudder. See pic - I shot it so you can see how close it comes in the up position to the void in the vert fin.
The bellcrank maxed out before anything else - interference from the edge of the access void for the bellcrank, in the fuse.

The difference was that my newbie had the pushrod way on the end of a longer control horn, compared with the oldie.
There is a hole halfway to the pivot point for more extreme throws.

You can see in the pics that neither stabilator was limited at the back end - it was at the bellcrank.
The control arm of the oldie was 1/2 the length of that of the newbie, with only one hole as an option.
So, it's in which hole on the stabilator control arm that the pushrod is set, that sets the throws.
I just picked up 1 and 1/2 more PT-19s and will get them out and take a look if they are of any different vintage than the ones we have.

Cheers - Peter
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Old 10-02-2017, 05:25 PM
  #30
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Peter, thanks very kindly for taking the time out to post the pictures; I take it you're flying the newer, blue fuselage airplane with the pushrod in the outer hole on the stab horn.

Just confirmed that my airplane is set up with the pushrod on the inner hole and the web aft of the pivot point (actually the stiffening lip) on the stabilator halves is contacting the relief cut-out on the rudder before the up arm of the bellcrank comes anywhere close to hitting the fuse wall at the relief slot. If I continue to pull on the "up" line until the bellcrank hits the fuse wall, the stab remains maxed and the pushrod just flexes. If I pull up on the vertical stab to give additional clearance, the stabilator can achieve a higher max throw. So, still thinking that either lifting the vertical or opening up the relief hole for the web will increase up elevator throw as your yellow fuse oldie appears to have. Does the oldie fly better than the newbie?

Wondering if additional "up elevator" can provide better ability to slow and flare the airplane during power-off landing phase.
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Old 10-02-2017, 06:06 PM
  #31
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This is the plane that I learned to fly Controline on. With that flying Stabilator why don't we see that on newer versions of Controline? No hinges!
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Old 10-02-2017, 07:28 PM
  #32
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Tom - I can see why the PT-19 was so popular - it actually had flying tendencies(!) and was pretty docile, compared to planes like the Fokker Triplane which seemed like barely controllable flying bricks. Of course, they were eye-candy for kids, who wouldn't want one of those when they were 7-8 years old.

H5606 - I changed the pushrod placement tonight after you brought attention to your situation.
Once moved, I seemed to get a lot of throw.
Here's a still shot of the linkage with the pushrod moved to the shorter hole (more throw). I think it shows the webbing you are talking about on the stabilator, used for adding rigidity.
Also, a link to a video of the stabilator once I moved to the shorter hole in the control horn, tonight. A video is worth a million words.
Even used slo mo! (trying out a borrowed gopro for slo mo). Video
.
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Old 10-03-2017, 05:22 PM
  #33
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Thanks again Peter - the video is most helpful; just the still photo alone confirms my suspicion that other/earlier renditions are capable of more elevator throw/travel.

Rather than focusing on the TE, I compared the amount of fuselage visible above the LE in your video-still and my Chinese version picture showing max up-elevator.

The amount of fuse visible above the leading edge in your airplane is clearly way more than what is visible in mine - there's also more light coming through the triangle relief slot on yours than mine most likely indicating a wider arc hole. Looks like my airplane's max travel is no more than your "newbie" airplane's minimum travel.

Filing open the carry-through relief slot in the rudder is probably the simplest way to achieve more throw in the "up" direction for my Chox PT-19.
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Old 10-03-2017, 05:41 PM
  #34
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Great the video helped - I was trying to show that triangular relief that you were interested in.
I am bringing another parts plane back to life.
The wing was broken in half about the centerpoint.
I put out a "RFS" today - a request for solutions - ha - before I overdesigned a fix.
The winner was .... packing tape.
It worked like a charm - abundant strength and rigidity.
I picked up a PT-19 engine/mount/landing gear for a reasonable price on eBay today.
Now I am looking for the tail fins, but I can make either or both of them.
Earlier pics below show an older Babe Bee and mount for the older style PT-19.
Last photos are sellers pics of the needed engine/mount/LG I found sitting on eBay, today.

Keep us posted on improvements, any pics or vid.

Cheers,
Peter G.
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Old 10-05-2017, 03:12 AM
  #35
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At some point back in the seventies, I got a replacement fuselage that came in a long brown, corrugated box direct from Cox Mfg, hinged at the ends and opening in the middle. It had the full cockpits, pilot busts, and (hidden from view here) instrument panels like that shown in pic #3. To my surprise, it had the current gen, "bridged" front end. It also had the separate (square, blue) fuel tank like the one shown on the left in picture # four and required a new firewall to replace the metal tank and original firewall. I can't remember if the tank-less, firewall came with the replacement fuse...

My original early gen wing broke in the center just like that one too, but I only remember it breaking from the LE up to the hole... I don't remember what happened to the airplane after that; it may have ended up in a trashcan or been given away at an auction in VA as a club donation.

Just out of curiosity, does the wing you have pictured have a chipped leading edge at the (I believe its the extreme right wing-tip)? You know where this is going - could this have actually been my airplane four-and-a-half decades ago? I don't recognize the engine and firewall though and realize it doesn't fit this gen fuse...

Pretty sure the back-plate for this gen fuselage was yellow and shaped like the black one you have in the last series of engine pics above.

Last edited by H5606; 10-05-2017 at 01:40 PM. Reason: added info
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