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Old Feb 16, 2009, 05:48 PM
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United States, Mt, Belgrade
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Build Log
Sterling Great Lakes 24'' Conversion

I am starting a build log for my 24'' span Sterling Great Lakes. I am building this aircraft with A/E/R/T.

I have built r/c since 1992 but have been out of flying for the most part since 2004 with new family and other interests. About a month ago I decided to get out this old kit and build it. I built a pt-16 from herr as free flight the month before and thought boy would it be nice to not have to chase this thing all over the place. I thought that it might be fun to try to convert it to r/c. I have never been into electrics as I was trained on glow my whole life. When I researched and found all the possibilities of electrics, I was amazed at how far technology had come in a few years. Then I found this site and now the juices are flowing!

I do not know the proper motor or battery yet. Any suggestions will be appreciated and given proper research. From evaluating the site I have found a few possibilities. I do have a rimfire brushless 28-26-1300 that I picked up at a swap meet. Due to the size of the airframe and the fact that I would like to ROG I feel that this may be too big (prop diameter is a limiting factor). I would like to put a 6'' 3 blade on it.

After wieghing the wood components and figuring motor weight and assuming 3-4 oz. running gear, I assume that the target wieght for this unit is going to be around 10-11 oz. The wood in this kit is poor (heavy, not to mention the stamping is way off) to say the least, so I have been cutting alot of my own pieces from the nicest 1/16 wood from local hobby shop. I dont figure that I need contest grade for this kit and how it is built.

also, I am wondering if anyone has experienced .032'' music wire torque rods being to flexible or do I need to step up one size?
Any comments would be appreciated.
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Old Feb 16, 2009, 05:57 PM
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Wilkes-Barre/Scranton, Pennsylvania, United States
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.032 wire rods will work if they are in tubes securely attached to the fuse structure to prevent flexing. Make certain the exposed portion leading to the control surface is as short as possible again to prevent flexing.

BM
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Old Feb 16, 2009, 06:04 PM
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United States, Mt, Belgrade
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I meant for the ailerons. I am afraid that I will get flex where they exit wing at 90 degree angle. they will be supported in short sections of aluminum tubing. the servo will be mounted conventionally in wing center with pushrods connecting it. I will be using a hs-55. I have never used such small servos before. not sure if it will be strong enough for 4 ailerons also.
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Old Feb 16, 2009, 06:18 PM
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Joined Jul 2002
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First welcome to rc groups and welcome back to aeromodeling.
Itís so cool to be able to revisit these models from our youth and convert them to rc.
That model is a little smaller than the ones I build so I would suggest checking out conversions by HanksGB and Konrad. They have converted a few models in the size of yours.
http://www.rcgroups.com/forums/showthread.php?t=609406
http://www.rcgroups.com/forums/showthread.php?t=965126
http://www.rcgroups.com/forums/showthread.php?t=832844
I have found 1/32 wire is way too flexible for aileron torque rods. I use 1/16 aluminum tube with 1/32 wire ends.
Glenn
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Old Feb 16, 2009, 07:03 PM
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Thanks for the threads glewis. It is nice how much information and help you can get on this forum. As for the torque rods, I will be trying a few different things. I will keep posting as I figure out what works.
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Old Feb 16, 2009, 07:24 PM
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Everett Wa.
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1/32 wire is wholly inadequate as a device for transmitting torque. All those well supported aluminum bearings (support) will do is keep the wire from bowing
I like to use 0.055 or no less than 0.047 wire if the torque rod span is short. For longer span rods such as you would need for scale size ailerons, I would use carbon tubes with the wire arms glued into the tube at right angles.

http://www.peck-polymers.com/store/Category.asp?Cguid={9FFC076A-6908-443D-9A5F-20BE389A3DC9}&Category=BuildingMaterials%3ACarbon+ Pultrusion

The HS 55 is strong enough.
As a general rule the landing gear in these Gummy Band kits are inadequate. Please do look at my Champ thread for ideas. I also like to do whatever I can to lighten up the tail (anything aft of the center of gravity).
Do a search on Dumas and Guillow stuff as they have some good 24 inch kits and this site has some good threads.

I think this is the best reference page on this site for any scale rubber band conversion.

http://www.rcgroups.com/forums/showthread.php?t=827861

Please take lots of photos and ask a lot of questions. We all are more than willing to help.

Glenn,
Thank you for the kind word. But it is HanksGB that has a lot more experience with this size biplane. I really love his Dumas Super Solution.
Now your bigger one is in a class all by itself.

All the best,
Konrad
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Last edited by Konrad; Feb 16, 2009 at 07:55 PM.
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Old Feb 17, 2009, 11:26 PM
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Thanks Konrad

You and Hank have done several great conversions with alot of great ideas that have helped with this conversion.
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Old Mar 04, 2009, 09:53 PM
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Slow going...

Here is pic with top wing framed. It is obviously not finished. I have been wieghing the components as I have finished them and I think I am shooting for an AUW of 9 oz. It has a total wing area of 161 sq. inches. I hope that the wing loading isn't too high. I have no problems with a fast airplane.

The covering is going to be tissue as this whole project started as me having a crazy pipedream of converting a standard "stick and tissue".

The motor I chose is a Rimfire ammo 12mm with gearbox and I am still trying to decide on a battery. Probably A small 2s 500ma or so. Does anyone have experiance with this set up for total run times?

The top wing will have ailerons as well. I just haven't removed them from the structure yet.

And no... For you people paying attention... the servo on the table is not for this model. HA
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Old Mar 04, 2009, 10:28 PM
Two left thumbs
Muncie, IN
Joined Sep 2006
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This should turn out to be a neat little bird! My only concerns are that using the original wood instead of copying it you may not be using really good wood, AND you've used up a complete, no longer available kit! Oh, well, I'll shut up now and enjoy watching it all go together.

Geoff
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Old Mar 05, 2009, 11:27 PM
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Geoff,

I know using up an old kit can be devestating. But, a kit is only pretty when it is actually put together. It just looks like a pile of parts when it is in the box. It has so much more personallity (not to mention the kit is happier when serving its original function) when it is all put together.

The original wood is actually not horrible (well some of it anyway) and I have remade some of the pieces where really bad. The spars were pretty hard but stiff and lighter than basswood. I also used the original trailing edges and wing tips as I wanted stiffness and the tips usually get some pretty good abuse. I will be remaking almost all of the formers with contest balsa and lightening as possible. If you look, the vertical was remade with a couple techniques found online here and is VERY light. the horizontal used some of the original parts, but I am not sure, I may redo it like the vertical.

Also, the planes from sterling have all stamped pieces duplicated on the plans so I can remake anything needed or duplicate the plane later. I think I will be enlarging it to a 30'' wing span next time to alleviate the weight problem. (too many beers like me I think!)

Don
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Old Mar 06, 2009, 10:09 AM
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Re Battery Packs: Try to make battery compartment large enough to try 700-800mah 20C 2S and 3S packs as may be needed. I would guess that with a 7x4 prop you will get about 8-10 minutes duration at an average 2/3 throttle cruising flight.
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Old Apr 15, 2009, 12:12 AM
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E-

Thanks for the advise. I have been playing around with the set-up and I am very pleased with the package. I am concerned that this will not be enough prop for a real slow plane- should fly fast. I am limited to this prop size. Does anyone know where to find three blade props? I would like to try one and see if it pulls too many amps.
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Old Apr 15, 2009, 12:52 AM
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Everett Wa.
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Take a look at the Vario Prop. But if you are looking for flight performance stick with the 2 bladed prop or even the single blade, but this is beyond the scope of a scale ship.

http://www.aircraft-world.com/shopdi...variable+pitch

Konrad
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Old May 02, 2009, 10:19 PM
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Vario props

Thanks for providing me with the site for the Vario props. My question (which may just be my incompetance) is the blades they list show a length of, say, 6.1''. Is this the length of the single blade, or the diameter of the total prop with all blades attached to the hub? I love the look of these props and will be bying one for sure if I can get one that has a total lenght of no more than 7.5''.

The progress on this build is much slower than I thought it would be due to having a new baby on January 6th. I thought this would be a good new baby project due to having the ability to cut and build "quietly" while he slept. Yeah right! I have enough time to cut one part at a time before he wakes up and squeels. Oh well it has been a great adventure so far. I will keep up dates coming as they happen.
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Old May 03, 2009, 05:06 AM
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Everett Wa.
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It is my understanding that this is the effective diameter. (it is. Its just that I haven't measured the diameter directly).

While the cost may be higher than most props. The adjustable pitch adds a very valuable parameter in matching the power of the motor to the need of the airframe. This is similar to what is done with gearboxes that have variable ratios. While flexibility often confuses many I like the ability to fine tune the performance that a gearbox and a variable pitch prop offers.
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Last edited by Konrad; May 03, 2009 at 05:11 AM.
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