TD .049 Powered C/L Scratch Build
#1
![Default](images/icons/icon1.gif)
Maybe I should first make sure I have a good TD...?
I tested 3 combinations of parts and they all produced 18.500 rpm with a 5x3 Cox prop.
All different P/L combos using the same crankcase, same backplate, same crankshaft.
tested with 33% nitro fuel.
All used the same old Tower Hobbies tach I've owned for 30 years...[do tachs read lower as they get older ?]
All 3 engines "felt good" in the hand but are miles apart from producing good results.
The plane is built similar to the Baby Flite Streakish plane [I posted a couple days ago] with the way the wing and fuselage get built.
I like the simplicity of NO SPARS...just using a strong LE and TE...and strong ribs [1/8" thick instead of the usual 1/16"]
That's a home made bell crank out of 1/16" aluminum and the pivot bushing was machined from a $6 aluminum standoff.
The fuselage is 1/4" thick medium balsa with a pair of 1/4" x 3.8" maple motor mounts sandwiched between 1/64" plywood doublers
![](https://cimg6.ibsrv.net/gimg/www.rcuniverse.com-vbulletin/1920x1080/img_0630_89d27dbb7534848367c07e59fcd4138253c11662.jpg)
![](https://cimg7.ibsrv.net/gimg/www.rcuniverse.com-vbulletin/1920x1080/img_0631_056b48a5b30e5b124ad50feef748c380a9682c6d.jpg)
I tested 3 combinations of parts and they all produced 18.500 rpm with a 5x3 Cox prop.
All different P/L combos using the same crankcase, same backplate, same crankshaft.
tested with 33% nitro fuel.
All used the same old Tower Hobbies tach I've owned for 30 years...[do tachs read lower as they get older ?]
All 3 engines "felt good" in the hand but are miles apart from producing good results.
The plane is built similar to the Baby Flite Streakish plane [I posted a couple days ago] with the way the wing and fuselage get built.
I like the simplicity of NO SPARS...just using a strong LE and TE...and strong ribs [1/8" thick instead of the usual 1/16"]
That's a home made bell crank out of 1/16" aluminum and the pivot bushing was machined from a $6 aluminum standoff.
The fuselage is 1/4" thick medium balsa with a pair of 1/4" x 3.8" maple motor mounts sandwiched between 1/64" plywood doublers
![](https://cimg6.ibsrv.net/gimg/www.rcuniverse.com-vbulletin/1920x1080/img_0630_89d27dbb7534848367c07e59fcd4138253c11662.jpg)
![](https://cimg7.ibsrv.net/gimg/www.rcuniverse.com-vbulletin/1920x1080/img_0631_056b48a5b30e5b124ad50feef748c380a9682c6d.jpg)
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init4fun (08-20-2024)
The following users liked this post:
init4fun (08-20-2024)
#3
![Default](images/icons/icon1.gif)
![](https://cimg7.ibsrv.net/gimg/www.rcuniverse.com-vbulletin/1920x1080/img_0641_0f5780b3c3e33b69daf6883092b9acb64e736c7d.jpg)
Here it is almost ready to fly at 6 7/8 ozs.
It's covered with tinted cellophane that was misted with 3M 77 adhesive.
The bladder holder looks like a gutted plastic fuel tank..but I made it out of 2 layers of 2 ox cloth and medium CA. I coated it with a smear of epoxy inside and out. I was afraid the fuel cell in the wing was going to doom the plane to having way too long of a nose. The nose ended up long enough as it is [I'd like to move the engine back after some flight tests.]
Still needs the fuselage fuel proofed and a nickle taped to the outboard wing tip.
The span is 30 inches not counting the wing tips.
This is the most extreme control line thing I've built for the .049 TD.
I'll want to see it fly on 40 foot Spiderline if it passes the test on 35 foot lines
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init4fun (08-21-2024)
#4
![Default](images/icons/icon1.gif)
Here she is at 7 1/8 ozs RTF on 35 foot long steel
The engine only puts out 18500 with a 5x3 instead of the normal 22,000 output we would expect to see back when a Cox TD .049 was REALLY a Cox TD .049.
I used .055" wire to connect the bell crank to the elevator which is much lighter than using 2-56 wire that is already threaded.
The drawback is that it is much more difficult to adjust the control response with the .055" wire. because you only adjustment is to use pliers to re-bend the control wire until it is just the perfect length.
Line tension was pretty good for this low revving TD. I used "leadout rake", some engine out-thrust and a tiny bit of right rudder to enhance the line tension.
I used a nickle for wingtip weight
![](https://cimg1.ibsrv.net/gimg/www.rcuniverse.com-vbulletin/1920x1080/img_0642_56c4cf1cbbde35280c8b7734aa725178f536d203.jpg)
Here she is at 7 1/8 ozs RTF on 35 foot long steel
The engine only puts out 18500 with a 5x3 instead of the normal 22,000 output we would expect to see back when a Cox TD .049 was REALLY a Cox TD .049.
I used .055" wire to connect the bell crank to the elevator which is much lighter than using 2-56 wire that is already threaded.
The drawback is that it is much more difficult to adjust the control response with the .055" wire. because you only adjustment is to use pliers to re-bend the control wire until it is just the perfect length.
Line tension was pretty good for this low revving TD. I used "leadout rake", some engine out-thrust and a tiny bit of right rudder to enhance the line tension.
I used a nickle for wingtip weight
The engine only puts out 18500 with a 5x3 instead of the normal 22,000 output we would expect to see back when a Cox TD .049 was REALLY a Cox TD .049.
I used .055" wire to connect the bell crank to the elevator which is much lighter than using 2-56 wire that is already threaded.
The drawback is that it is much more difficult to adjust the control response with the .055" wire. because you only adjustment is to use pliers to re-bend the control wire until it is just the perfect length.
Line tension was pretty good for this low revving TD. I used "leadout rake", some engine out-thrust and a tiny bit of right rudder to enhance the line tension.
I used a nickle for wingtip weight
![](https://cimg1.ibsrv.net/gimg/www.rcuniverse.com-vbulletin/1920x1080/img_0642_56c4cf1cbbde35280c8b7734aa725178f536d203.jpg)
Here she is at 7 1/8 ozs RTF on 35 foot long steel
The engine only puts out 18500 with a 5x3 instead of the normal 22,000 output we would expect to see back when a Cox TD .049 was REALLY a Cox TD .049.
I used .055" wire to connect the bell crank to the elevator which is much lighter than using 2-56 wire that is already threaded.
The drawback is that it is much more difficult to adjust the control response with the .055" wire. because you only adjustment is to use pliers to re-bend the control wire until it is just the perfect length.
Line tension was pretty good for this low revving TD. I used "leadout rake", some engine out-thrust and a tiny bit of right rudder to enhance the line tension.
I used a nickle for wingtip weight
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init4fun (08-25-2024)
#5
![Default](images/icons/icon1.gif)
This is cool as poop!
And knew in an instant what the carpet sleeve was for as soon as the picture scrolled into view - a super simple, ingenious launch means - just pull the airplane out when you pick up the handle -
And knew in an instant what the carpet sleeve was for as soon as the picture scrolled into view - a super simple, ingenious launch means - just pull the airplane out when you pick up the handle -
The following 2 users liked this post by H5606:
combatpigg (08-22-2024),
init4fun (08-25-2024)
#6
![Default](images/icons/icon1.gif)
It's been quite a few years since I first saw the carpet sleeve launcher used and I thought it was totally INSANE.
Way too dangerous looking..!
What I saw was a .15 powered combat plane in one of those launchers and I just thought you'd have to be nuts to turn your back on a running engine and jog out to pick up your handle.
Since then I've seen several of those launchers in use.
I had an old DISH Network antenna stand that wasn't getting any use and it was a simple deal to fasten a piece of 3/4" plywood to the upper brackets.
The antenna stand was basically the most perfect piece of junk for this project.
For big, powerful.35 size planes the base needs to have dead weight [like cinder blocks] laying on the base footing to keep it from tipping over.
Last edited by combatpigg; 08-22-2024 at 09:32 PM.
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init4fun (08-25-2024)
#7
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Admire ability to fly inverted - for laps at a time no less - a skill I never mastered let alone "8's" of any sort - psyched-out fear of "dumb-wristing" while inverted and proximity to the ground, along with aging reflexes, has reinforced a self-imposed, mental-block over time - hoping to overcome this barrier before it's too late. Landing back at launch point only complements the whole flight.
Looks like the airplane has enormous line-tension to be doing the vertical "8's" where the airplane appears to be directly overhead - and since you're considering 40' lines.
Looks like the airplane has enormous line-tension to be doing the vertical "8's" where the airplane appears to be directly overhead - and since you're considering 40' lines.
#8
![Default](images/icons/icon1.gif)
Admire ability to fly inverted - for laps at a time no less - a skill I never mastered let alone "8's" of any sort - psyched-out fear of "dumb-wristing" while inverted and proximity to the ground, along with aging reflexes, has reinforced a self-imposed, mental-block over time - hoping to overcome this barrier before it's too late. Landing back at launch point only complements the whole flight.
Looks like the airplane has enormous line-tension to be doing the vertical "8's" where the airplane appears to be directly overhead - and since you're considering 40' lines.
Looks like the airplane has enormous line-tension to be doing the vertical "8's" where the airplane appears to be directly overhead - and since you're considering 40' lines.
Notice the way duct tape was used to enhance it's aerodynamic efficiency.
The wood prop kind of conflicts with the UNBREAKABILITY THEME.
The engine mount I believe is available at Brodak...otherwise I'm sure you've got the materials to whip one out.
There should be plenty of campaign signs floating around soon.
I learned how to fly stunts with the help of this book... It's shocking to see what the price is...! It does have a plan for a .35 powered Piper Cherokee [that needs to be scaled up to full size be usable]
Last edited by combatpigg; 08-26-2024 at 10:27 PM.
#9
![Default](images/icons/icon1.gif)
Here is the MAN-WIN TRAINER...!! https://www.ebay.de/itm/224664826383
Notice the way duct tape was used to enhance it's aerodynamic efficiency.
The wood prop kind of conflicts with the UNBREAKABILITY THEME.
The engine mount I believe is available at Brodak...otherwise I'm sure you've got the materials to whip one out.
There should be plenty of campaign signs floating around soon.
I learned how to fly stunts with the help of this book...https://www.amazon.com/How-Fly-U-Con.../dp/B0006CM3LQ
It's shocking to see what the price is...! It does have a plan for a .35 powered Piper Cherokee [that needs to be scaled up to full size be usable]
Notice the way duct tape was used to enhance it's aerodynamic efficiency.
The wood prop kind of conflicts with the UNBREAKABILITY THEME.
The engine mount I believe is available at Brodak...otherwise I'm sure you've got the materials to whip one out.
There should be plenty of campaign signs floating around soon.
I learned how to fly stunts with the help of this book...https://www.amazon.com/How-Fly-U-Con.../dp/B0006CM3LQ
It's shocking to see what the price is...! It does have a plan for a .35 powered Piper Cherokee [that needs to be scaled up to full size be usable]
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combatpigg (08-28-2024)
#10
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One way to make a Cox .049 reed valve engine fully aerobatic is to drill a hole in the fuel tank and run a small silicone fuel line from the engine's fuel inlet out to a plastic 1 oz or 2 oz tank. The Hayes tanks are the greatest for this if you can find them. The best fuel line for .049s was Sullivan Small. I think both Hayes and Sullivan are getting hard to find now
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H5606 (08-29-2024)