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Sep 15, 2010, 12:05 AM
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gjalbert's Avatar
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Discussion

Profile PT-19


I've been wanting to build a simple PT-19 model for a long time. I had one of the Cox control line PT-19 models as a kid and wanted something reminiscent of it. Inspired by the great SEMFF WWII combat plane designs of dz1sfb's (Ken's) I decided to design my own. With those designs as a guide this came out looking pretty good, if I do say so myself.

The basic equipment is the same as that used on the SEMFF WWII combat planes, see this thread:

https://www.rcgroups.com/forums/show....php?t=1012551

All up weight on mine came out to 205 grams, with battery.

Maiden tomorrow, weather permitting.

Plans to come.

Thanks Ken for the great base upon which to build.

Gary
Last edited by gjalbert; Nov 20, 2010 at 03:11 AM.
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Sep 15, 2010, 11:15 PM
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I was able to maiden it today and got a little bit of video. As seems true with lots of my maiden flights, it was a bit tail heavy at first, though only a little bit this time. There was a good wind blowing too, making flying interesting.

All in all it flies pretty well and looks great in the air.

Just a short video of the first launch. Had to get it down and move the battery a bit forward. Handled nicely after that.

Gary

Profile PT-19.wmv (0 min 53 sec)
Sep 15, 2010, 11:31 PM
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Plans


Here are the plans. Full size, tiled letter size, and tiled A4 size.

Nothing revolutionary here, modeled closely on the SEMFF WWII combat planes as I mentioned before.

Specs:

Wingspan:29 1/4 inches
Length: 22 inches
Motor: hexTronik 24gram Brushless Outrunner 1700kv
ESC: TURNIGY Plush 10amp 9gram Speed Controller
Servos: 7g Sub-Micro Servo
Receiver: DSM2 Compatible Parkflyer 2.4Ghz Receiver

Made of Dow FFF from Lowes.

Gary
Last edited by gjalbert; Sep 15, 2010 at 11:49 PM.
Sep 16, 2010, 06:30 AM
Ken's CAD Models
dz1sfb's Avatar
Kudos! in triplicate Gary!

I am so proud of you. This is what I was hoping that folks would be able to do. Take an idea and run with it.

Almost like having granchildren,
Ken

PS - Do you know what the wing area is?
Sep 16, 2010, 11:34 AM
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Gary,

That's a great looking model. I'll have to watch the video at home. I love the Pt-19's (and the PT-20/21's) as well. If you ever are itching to do a balsa build, check out Peter Rake's 'Ryan's daughter'. It is my winter project.
Sep 16, 2010, 12:59 PM
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Thanks for the comments guys. Like I said I've wanted to build some version of this airplane since I got back into RC last year. I had that Cox control line version when I was a kid and never really got to where I could fly it.

This one I can fly!

I just need to put some roundels on it and paint the horizontal stab yellow like originally intended and I'll have it the way I want it.

Gary
Sep 16, 2010, 03:53 PM
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Gary,
A VLF version of this would be really cool also. Could mount LG in the wing, and move the wing to the bottom of the fuselage. What the heck, add a rudder servo and make it about 20% larger to boot.

Not too much to ask (LOL!)
Ken
Sep 16, 2010, 05:55 PM
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Ken,

I originally considered the VLF style, but decided that for my first design the other style would be easier. Maybe not much though. I did have to compromise a bit on the wing and horizontal stab positions as a result. The VLF would have let me get those more correct.

I likely would have needed to exaggerate the vertical dimension of the fuselage in order to make enough room for the equipment, but that probably wouldn't have been too much of an issue.

I did design in a rudder into the plan on this one, though it isn't super effective. Probably making it a bit larger would have increased its effectiveness. Frankly, this airplane doesn't need a lot of rudder effect. It does help to make flatter turns for low altitude slow speed passes, though, and is sufficient for that as is.

I think this one really needs to be done with your latest full-fuselage concept. If done right, the frame / fabric lines could be baked in for a real authentic look.

By the way, the wing area came out to about 141 square inches.

Gary
Sep 16, 2010, 06:11 PM
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Vlf?
Sep 16, 2010, 06:53 PM
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Quote:
Originally Posted by kdahlhaus
Vlf?
VLF = Vertically Laminated Fuselage.

Check out Ken's designs here:

https://www.rcgroups.com/forums/show....php?t=1012551

You will see that he has two styles, one cruciform profile like I did here, and another with vertical laminations forming the fuselage, with compartments to hide the electronics.

Gary
Sep 16, 2010, 07:42 PM
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Ah ok thanks. I love Ken's VLF's, just missed that term.
Oct 08, 2010, 01:56 PM
It's just a plane.
ZackJones's Avatar
What paint did you use to paint it? I've cut out the tiled plans and will start building one soon.
Oct 08, 2010, 09:38 PM
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It was the cheap acrylic from Micheal's, Apple Barrel brand I think. I applied it with a Harbor Freight airbrush. It takes a several thin coats to get coverage, but looks great when done.

I'd love to pictures or video once you get it done.

Gary
Oct 08, 2010, 10:58 PM
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Another thing to consider when building this is to add a carbon spar to the wing. I did not do that in mine, and it isn't shown in the plans, but the wing is a little soft when made of FFF. The wing will flex a LOT at the bottom of a loop unless power is reduced. I haven't folded it yet, but it really flexes. It does have the effect of creating some dihedral both upright or inverted, so it flies very nicely inverted.

I intend to add a spar to mine soon, just to stiffen it up a bit.

Gary


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