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Author Topic: New project  (Read 1123 times)

Online Gary Dowler

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New project
« on: June 16, 2018, 02:29:05 AM »
I was just given a kit by a friend as a thank you for helping him at the regionals. It's a Sterling PT-19 kit. 48".   This is going to make my first sport scale model, which I intend to compete with next year.  It's typical Sterling, heavy ass wood, terribly rough "finish" on everything, etc, but weight is a purely secondary consideration on this one. Though reasonable wing loading is good, it's by no means intended to do more than go round and round, perhaps up as high as 45deg, but that's it.
It will have throttle and brakes and flaps, that's it. Should be a fun project.

Gary
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Offline Tim Wescott

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Re: New project
« Reply #1 on: June 16, 2018, 09:27:34 AM »
Get your documentation package first, and build to that!

Maybe I'll be there with my profile Ercoupe.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Gary Dowler

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Re: New project
« Reply #2 on: June 16, 2018, 11:08:23 AM »
Get your documentation package first, and build to that!

Maybe I'll be there with my profile Ercoupe.
The search for just the right prototype began yesterday. This should be fun.

Gary
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Online Gary Dowler

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Re: New project
« Reply #3 on: July 01, 2018, 06:23:37 PM »
Just won a bid for a OS 40FP that will power this project. I'm convinced it's more than is necessary for it, but scale planes tend to be heavy and I suppose better to have too much power than not enough. Should have it in 10 days or less.

Now it's time to look at radio equipment. The flaps/throttle will be r/c on this one. This will be new ground for me.  Transmitter, two servos, a battery and charger will bump this up about another $200 or so. Oh well, I'll work a day of OT to cover it I suppose so I keep the house CFO happy.


Gary
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Offline Tim Wescott

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Re: Sterling PT-19
« Reply #4 on: July 01, 2018, 06:52:28 PM »
You need to rename the thread!

There's less expensive options for the radio.  If you can't find one used on Craigslist, there's always Turnigy:

https://hobbyking.com/en_us/turnigy-tgy-i6-afhds-transmitter-and-6ch-receiver-mode-2.html
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Sterling PT-19
« Reply #5 on: July 01, 2018, 07:23:33 PM »
This is the one I'll be using: https://hobbyking.com/en_us/hobbyking-gt2e-afhds-2a-2-4ghz-2-channel-radio-system.html.  It has a 3rd channel that's just click-on, click-off, which could be used for flaps if you wanted to go cheap.  I think I'd consider a radio that could be programmed for a slow flap up & down, though.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Gary Dowler

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Re: Sterling PT-19
« Reply #6 on: July 01, 2018, 08:25:53 PM »
This is the one I'll be using: https://hobbyking.com/en_us/hobbyking-gt2e-afhds-2a-2-4ghz-2-channel-radio-system.html.  It has a 3rd channel that's just click-on, click-off, which could be used for flaps if you wanted to go cheap.  I think I'd consider a radio that could be programmed for a slow flap up & down, though.
That's almost exactly the radio my local hobby shop owner was showing me the other day.  The link didn't show a price. The one locally was $109 for the radio, then add in servos and a battery and charger, etc.
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Offline Tim Wescott

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Re: Sterling PT-19
« Reply #7 on: July 01, 2018, 10:33:55 PM »
That's almost exactly the radio my local hobby shop owner was showing me the other day.  The link didn't show a price. The one locally was $109 for the radio, then add in servos and a battery and charger, etc.

$23 from Hobby King, and servos start at around $5 -- I'm not sure why it wasn't showing a price, though.

If you get it from them, double-check that it has the 3rd channel.  The first channel is steering, which would take some modification to turn into anything useful.  The second is throttle, which is set for 'lectric RC cars, meaning it centers at 30 or 40% so that you have some room for going backwards.  You either need to modify the throttle channel, or you need to play some games with the throttle linkage geometry so that it idles at that "center" and still goes to full throttle.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Paul Smith

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Re: New project
« Reply #8 on: July 02, 2018, 08:15:03 AM »
The FlySky 3-channel car controller works fine for me.  I have eight airplanes and a launcher working off of one $40 transmitter.  No charger required. It's built into the transmitter.

You can set up the trigger for idle with your finger off the trigger and push forward for shutoff.

You can use four AAA throwaway batteries in the wing tip, the weight is right for carrier and scale.  At $2 a set, you can trow away A LOT of AAA's before to cross the payback curve of Lipo, Lipo charger and voltage regulator. 

Your system calls for 4.5 to 6.0 volts.  You can hit this easy with NiCad or carbon zinc.  Not so easy with Lipo, 3.7 or 7.4, just like Goldilocks.


Flap speed?  Not to worry.  The judges can't see flap speed.  A more significant issue is half for takeoff and full for landing.  If I were judging I would see that.
Paul Smith

Online Gary Dowler

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Re: New project
« Reply #9 on: July 06, 2018, 12:15:22 AM »
Ok, youse guys is right. Brakes will not be linked to the down elevator.  It will Either be 3 line throttle with brakes on the trigger for greatest versatility and flaps acting off a proportional button, or just a 3 channel set up with throttle on the trigger and brakes and flaps both on proportional buttons.

Thoughts?

Gary
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Online Gary Dowler

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Re: New project
« Reply #10 on: July 08, 2018, 04:35:46 AM »
Well the PT-19 has morphed into a PT-26, if I can source a canopy for it


From comparison of photos this canopy appears identical to that on the T-6. A email to the Canadian Warplane Heritage Museum in Ontario will hopefully shed light on this.

Does anyone on the site vacuum form such parts? If I were to provide dimensions and drawings, not to mention suitable payment, would anyone have the ability to assist in this?

Gary
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Online dennis lipsett

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Re: New project
« Reply #11 on: July 08, 2018, 09:55:56 AM »
Interestingly enough that model it was designed to be powered with a 15 sized engine. I had one a lifetime ago and used an OS15 steel fin for power. It was rudder only with 3 position throttle control. Super regen of course. Thankfully you made the whole top of the model removable so it was easily serviceable. plenty of dihedral made it stable and it was flown for a long time. Don't ask how many battery packs I soldered together in the lifetime of that model. Fortunately I had KMD servos instead of escapements for it. they were later sold by Royal products in the USA. Unfortunately it needed a separate battery pack for the receiver and battery packs for the servos. Four point five for the receiver Three volts for the rudder and 1.5 for the throttle. Push button  Hinode TX. For the record the model is a pain to build. Typical Sterling quality. The motto for building a Sterling then was replace, replace,replace the wood.

Online Gary Dowler

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Re: New project
« Reply #12 on: July 08, 2018, 10:11:30 AM »
Interestingly enough that model it was designed to be powered with a 15 sized engine. I had one a lifetime ago and used an OS15 steel fin for power. It was rudder only with 3 position throttle control. Super regen of course. Thankfully you made the whole top of the model removable so it was easily serviceable. plenty of dihedral made it stable and it was flown for a long time. Don't ask how many battery packs I soldered together in the lifetime of that model. Fortunately I had KMD servos instead of escapements for it. they were later sold by Royal products in the USA. Unfortunately it needed a separate battery pack for the receiver and battery packs for the servos. Four point five for the receiver Three volts for the rudder and 1.5 for the throttle. Push button  Hinode TX. For the record the model is a pain to build. Typical Sterling quality. The motto for building a Sterling then was replace, replace,replace the wood.
Yes, it's fairly typical of Sterling as far as wood goes. But I've seen worse!   I am hard pressed to imagine how you flew a scale plane with a 48" wing with a .15.  If needed I'll replace, otherwise it's getting used. This has to be ready before the regionals next year. Sounds like a long way off, but you know as well as I do that it's just around the corner.
This kit was designed for R/C, but plans cover conversion to C/L.
Just need to source this canopy.

Gary
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Offline Trostle

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Re: New project
« Reply #13 on: July 08, 2018, 12:46:44 PM »

Well the PT-19 has morphed into a PT-26, if I can source a canopy for it

Gary

You might check the Park Flyer website at

http://parkflyerplastics.com/cart/index.php?main_page=index

You might be able to adapt some pieces from from there, but they might be a too large for your scale.

Keith

Offline john e. holliday

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Re: New project
« Reply #14 on: July 08, 2018, 03:15:17 PM »
Gary, I flew RC for a few years and was amazed at some of the planes being flown and the ones I flew with engines that seemed to be too small in a persons thinking that has flown control line.   Remember they don't have the drag of the control lines and yes when converting an RC to control line we went to a larger engine.  One .15 size plane I flew had a 6 foot wing.  I think I'm safe in saying that most of the RC planes were over powered for just general sport flying. H^^
John E. "DOC" Holliday
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Online Gary Dowler

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Re: New project
« Reply #15 on: July 08, 2018, 07:53:44 PM »
You might check the Park Flyer website at

http://parkflyerplastics.com/cart/index.php?main_page=index

You might be able to adapt some pieces from from there, but they might be a too large for your scale.

Keith
Thank you Kieth. I looked further at that site and it looks like they have one that will work!!

Gary
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Online Gary Dowler

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Re: New project
« Reply #16 on: July 10, 2018, 12:22:46 AM »
It feels like this is starting to happen now.  Sourced the canopy as well as photo pack and three views of the prototype, just have to order these things,  my engine arrived today as did my brakes kit.  Time to get some parts cut out!!
Gary
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Online Gary Dowler

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Re: New project
« Reply #17 on: July 15, 2018, 04:23:51 PM »
Canopy ordered.  Spent several hours the last couple days cutting out parts. Didn't want to do this, but I have to replace a lot of the wood. No matter how careful I am a lot of break out is occurring on the back side of the parts.


I was willing to accept the weight penalty if the original wood to get speed of assembly, but not with parts that will result in compromised joints. Oh well, this will make it a little lighter as well.

Also got my first break in run on the engine for this. I'd bought a OS40fp for it. Looked virgin when I got it. But I found a lot of oil residue crud inside it, like they tried to run it.  Problem was the cylinder head, specifically the glow plug hole. About 1/2 in there was an issue with the threads. It would not allow a glow plug in more than 1/2 way from either direction.  Bought a 1/4-32 tap and chased the threads and it was good as new.

Gary
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Offline wwwarbird

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Re: New project
« Reply #18 on: July 15, 2018, 07:07:58 PM »
Well the PT-19 has morphed into a PT-26, if I can source a canopy for it


From comparison of photos this canopy appears identical to that on the T-6.

Gary

 The PT-26 and AT-6 canopies are quite a bit different from each other.
Narrowly averting disaster since 1964! 

Wayne Willey
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Online Gary Dowler

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Re: New project
« Reply #19 on: July 15, 2018, 11:32:32 PM »
Wayne, yes, after more looking you are correct.  The middle section is almost identical, but the forward and aft sections are noticeably different.  When mine arrives Ill have to evaluate it to see if its good enough for an entry level scale plane viewed from 15' away.  If not, perhaps I can hand make the fore/aft sections and still use the middle part.
It would be easy if I had a vacuum forming setup and could just make it properly to begin with.

Gary
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Online Will Hinton

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Re: New project
« Reply #20 on: July 16, 2018, 06:54:59 PM »
Gary, do a search here for heat forming canopies from a plastic drink bottle.  I've done it and it works great.  Carve your canopy mold buck out of balsa, cut the bottom off a plastic drink bottle and wedge the mold buck tightly into the bottle by cramming scraps in beside it.  Then slowly and carefully heat it with your moneycote gun and watch the magic happen.  I use the bottles from Wal-Mart that a flavored water called "Clear" comes in because they are quite thick and work well.
On my S2F Hellcat profile I even carved the frame into the buck and it looks great.  (Now if I would only get busy and put the fractured beast back together!)  Ball diamond one, Will nothing, game over!
John 5:24   www.fcmodelers.com

Online Gary Dowler

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Re: New project
« Reply #21 on: July 17, 2018, 12:12:23 AM »
Will,

Thank you very much.  I will have to give that a try!  I was wondering where I might source clear plastic sheet to try something with, great idea!

Gary
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Offline john e. holliday

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Re: New project
« Reply #22 on: July 17, 2018, 11:49:56 AM »
The soda bottles work good for making canopies.   It takes some trying to get the one you like.   Remember to stuff all the open space between the mold with scraps of balsa.  the tighter the fit the less you have to shrink the plastic.  Also not all bottles of drink are the same material. D>K
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Online Gary Dowler

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Re: New project
« Reply #23 on: July 17, 2018, 09:47:24 PM »
The soda bottles work good for making canopies.   It takes some trying to get the one you like.   Remember to stuff all the open space between the mold with scraps of balsa.  the tighter the fit the less you have to shrink the plastic.  Also not all bottles of drink are the same material. D>K
Roger that.   Hoping to give it a try just for fun tomorrow.

Gary
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