An Old School “pattern" plane , finally with plans - Page 2 - RC Groups
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Aug 03, 2017, 10:35 AM
gpw
gpw
“There’s no place like Foam”
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Funny , we were most successfully powering this with the DCM-189, J-250 motor , geared running a Large 12X3 , 12X6 GWS SlowFlyer prop, and 7 (seven, heavy ) 600mah nicad pencells , what we refered to as the 50 cent motor .
Looks like today a 13K Blue Wonder motor and a light lipo battery would easily pull it all over the sky, no trouble !
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Aug 04, 2017, 08:23 AM
gpw
gpw
“There’s no place like Foam”
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Here’s how it looks on a sheet of FFF . We chose the Green Guard , because we had it handy , it's a little heavier than the Blucor , but is straighter, stiffer, and with the new light weight gear , we’re sure to beat the old weight anyway .

Plenty left on the sheet for another project .
Aug 04, 2017, 05:14 PM
Registered User
I have mine cut out and the hinges taped. I could not find a straight 1/4" x 1/4" so I substituted a CF rod. I used lightweight spackling to square up with the fuselage. The motor mount is poplar I turned on a lathe but it could have easily been cut out of ply. I'm going to slap a little colored tape to help with orientation, install the hardware and I should be good to go.
Aug 04, 2017, 05:57 PM
gpw
gpw
“There’s no place like Foam”
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Oh NICE !!! You Beat me to it !!! hahaha Carbon rod should work great !!!
Aug 06, 2017, 07:55 AM
gpw
gpw
“There’s no place like Foam”
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Ok , this may sound Crazy , but I was looking at the fuselage , and thought , “ what if we used a Foam Crutch instead of the Balsa or Spruce stick, CF rod, Bamboo , whatever. so we made one , and we'll try that . That should save a little weight , yet still add the “stiffness” required to prevent flexing in flight . a good test for that idea , and if it affects flight characteristics significantly . (?)
Aug 06, 2017, 11:55 AM
Registered User
It’s a little windy today but I put mine in the air after church. I had to trim in a lot of down elevator but knew it was tail heavy before I ever launched. It handled the wind pretty well but I have way to much throw in my control surfaces so it was a little spastic. My first landing was great, I just laid it on it’s belly, soft as pulling a blanket up on a baby. I launched again and made some very axial rolls both directions and did fine until I lost orientation and caught the overcompensation spasms; plunging it nose first into the ground. Broke the poplar motor mount but other than that, everything was fine. Even though the throttle was off it hit pretty hard but thanks to the CF shaft running the length of the fuslage, no significant damage. The mount should have been plywood and I can easily replace it.

So, a few build observations. I could not figure out how to get one servo to control the ailerons because the cf rod was in the way on the bottom and if I put it on top I had a very sharp control rod angle. I used a y-harness and two servos, laying them on their sides on the top of the wing.

When I rigged up the control rod for the rudder, the whole tail section would flex when cycling so I added some BBQ skewers for support. Since this is a profile plane, I need to get a receiver with end connectors because the one I’ve got sticks out farther than I like.
I used a 50g, 820 KV motor with a 1300 mA 3-cell battery but think I could have used a little heavier motor and some more KV. Using a 9 x 5 prop it had enough power but I had to go over half throttle to maintain good control. Once trimmed right, I think this thing will float.

This is going to be a fun plane once I get it trimmed properly.
Aug 06, 2017, 11:57 AM
Registered User
Weird, the pictures did not go so I'll try again.
Aug 06, 2017, 01:00 PM
gpw
gpw
“There’s no place like Foam”
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Fish, That looks SUPER !!!
I hope the crutch stiffens things up a bit . I never noticed much flexing the first time , and it flew fine … and while we’re on that subject , lets just throw in EPP planes which flex like crazy , but fly fine . I don’t think Foamies have to be completely rigid , birds arent …

Although the motor , wing and stab are on the same line , you still might need small thrust adjustments .. schmaybe” ? Once we find the ideal COG, we mark it clearly under the fuselage ( usually as to battery location too) … so we can get that again .
Last edited by gpw; Aug 06, 2017 at 01:06 PM.
Aug 06, 2017, 01:17 PM
gpw
gpw
“There’s no place like Foam”
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Fish , I remember in those days we did the ailerons with one servo , a slot cut for the servo body in the wing right next to the fuselage , then a slot cut in the fuselage so a LONG servo arm could pass through , allowing control rods on both sides .. pretty simple and it never over stressed our 9g servos .
Although 3D control rates are Fun , much smoother flying results from less control movement . those surfaces are Big … less deflection is less drag … We used to love doing really Big vertical figure 8’s … Dual rates are really handy … Our new QX-7 has 3 rates …
Aug 06, 2017, 01:30 PM
Registered User
Well, the tail does flex in the right direction to assist with the control surface. I just was not sure how this would impact certain maneuvers or if it would complicate their execution. Flight test reviewed an articulating plane some years back (on youtube). It flew but not particularly well. However in conjunction with control surfaces, it might be interesting. I'm going to leave mine on for now but may eventually take them off just to see the difference.

Good idea on the aileron servo. Did you have to compensate by installing the control horns on different portions of the wings? In other words, maintain the same servo-to-horn-angle on each side?
Aug 06, 2017, 05:03 PM
Retired CAD guy
birdofplay's Avatar
HOW about a fully built up BOX fuse and Symmetrical Foil version ?

Foam sheeted wings with CF spar and lightening holes

NOTE: some parts below are no fully developed "yet".
I intend to add alignment tabs and slots, plus formers and rib supports
for easier building.

Like This ...
Aug 06, 2017, 05:47 PM
Registered User
Replaced the motor mount, tamed down the throws and I can say it flies as GPW said. Long gentle turns but capable of turning on a dime if needed (a great bank and yank plane). Hitting the rudder at level flight just turns the plane without much wing drop; it just turns in place. Rolls and loops (inside and out) are no problem. Knife edge is fairly good but with the small fuselage cross-section you have to have some speed and stay on the rudder pretty hard. The wheel pants (which I do not have) might help with that.

Also, my 820 KV motor probably is part of the knife-edge problem. A little more speed would help. I suspect an 1100 to 1600 KV motor range would work great. My CoG is at 32% of the inside wing cord which makes it float like a feather but I suspect moving it forward a little might improve some maneuvers and hinder others. I'm happy right now at 32% but this probably still classifies as tail heavy and I have to trim in some down elevator to keep it level. This is by far the easiest landing plane I've ever flown. The glide path with motor off requires only a little up elevator and is smooth as silk. A little flare a foot above the ground and you have an easy belly landing.

Birdofplay, Your plans look good and should fly fine as far as I can tell. GPW, looking forward to your flight report. I'm wondering if I lost anything by skipping the wheel pants.
Aug 07, 2017, 02:06 AM
flyin' fool
goldguy's Avatar
Quote:
Originally Posted by JohnM
If I build one, it would need to be designed around a 2S 300mah power system as that is my new standard.
Any suggestions for a motor/prop? and what size should I scale it down to? 75%?
From the printed planes, it appears that it is has both a wingspan and length of ~30.5"
This appears large as compared to the dimensions of the UMX Pitts
A 75% scale would be about 22.5" wingspan and length
2S 300 power setup....................
https://www.rcgroups.com/forums/show...8162-Park-Lark
Aug 07, 2017, 05:50 AM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Compensate … Naa!!! It worked fine … Fish , glad to hear it all worked out for you . You could try Scotch taping the wheel pants part on , just to see...
Birdo , that’s looking COOL !!! You going to make kits ? ( OK with me )

Yes , finding the right power system is important , the old J250 GWS gear drive worked OK , but seems Fish is working that out with modern motors ( Thanks ! )
Last edited by gpw; Aug 07, 2017 at 06:04 AM.
Aug 07, 2017, 09:34 AM
Retired CAD guy
birdofplay's Avatar
I might make kits - we'll see how it go's !
OK ! ? .. .well Thanks for the Oky Doky ;>}

I also have a Taurus and plans to do the Kwik Fli and XLT.
and more on request if there's enough interest.

These should be lighter than the originals and maybe not as fast either, but ....
MAYBE we could cheat with the addition of one of those very inexpensive flight controllers
to make them even more solid, eh ? ! :>}

Bob @ Hoosier Cutout Service


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