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TeeDee .049

Old 04-09-2016, 09:36 AM
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RickP
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Default TeeDee .049

Hi Guys,
I am breaking in a new old stock TD 049. I think I am finally there. I ran about 1 1/2 qt of fuel through the engine. I kind of want to tune it up now and see how hot I can get it to run. Here are the specifics:

Tee Dee .049
Two head shims
25% nitro
Back plate pressure fitting
3 oz bladder tank
fine thread NV (128 tpi?)
6x3 prop

I am getting 18K right now and that seems to be as hot as it will run, but I can't really get any adjustment on the NV which makes me think something is wrong. The NV was so far out it was practically falling out. Yet when I pinch the line I hear no change in RPM and if I hold it longer it will drop or quit. Here are some questions:

How much RPM should I expect from this set up?
What is the base NV setting with the fine thread?

I think I am going to break down the test bench and inspect it closely. I noticed the venturi loose, so I had tightened it, but I wonder what else might be wrong. Much thanks in advance!
Kind regards,
Rick
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Old 04-09-2016, 01:16 PM
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Pond Skipper
 
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1 1/2 qt of fuel ?? wow that's a lot of fuel!

Note a 6x3 at 18k static is producing very good power.
17.6oz thrust / .154hp / 115w

Did you plug in the back plate pressure line into the tank to put pressure on the bladder?

You have ran a ton of fuel through the engine it only needed 6oz of fuel to break it in.
Since all this has been static the ball socket has been stressed with a 6x3 prop.
Odds are very good you have a loose socket now and need a reset tool to fix.
You will need to check this before running any further. Always bench test with less
prop to keep the load off the ball socket and keep it a tad rich for further compensation.

Only brief peak settings for quick power / rpm check on the bench.

You can take the NV body off the carb body remove the NV put fuel line on the nipple
and flood fuel through to blow out any possible hairs, silicon or any foreign materials
that may have gotten at the feed hold to the venturi.

If the Venturi was found loos this would for sure reduce suction and the NV would end
up out far to compensate.

I always pull the NV off wipe it down with oil to gather any oxidation trash on the metal
reoil the threads and reset.

Before running I oil all threads helps to seal.
Back plate
Glow plug
Cylinder
Venturi
NV
The carb body collar if the engine is completely apart.
Crank case on the outside before slipping over the carb body.
Crank shaft and prop plate before tapping back on always use
a thrust washer steel or phenolic (I prefer phenolic less heat)

Last edited by Pond Skipper; 04-09-2016 at 01:31 PM.
Old 04-09-2016, 04:09 PM
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combatpigg
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1.5 quart..?
That is over 3 hours of running...!
Old 04-10-2016, 05:14 AM
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I don't normally use pressure so correct me if I am wrong but I think the fine-thread needle is for higher bladder pressure so perhaps with backplate pressure you should be using the standard needle valve.

Also, after squirting some fuel through the needle valve assembly, check that all three holes are clear on the venturi.

Make sure you do not tighten down the venturi too much or you will break the carb body.

Good luck,
George

Last edited by gcb; 04-10-2016 at 05:22 AM.
Old 04-10-2016, 05:17 AM
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The fine thread needle is better for adjusting the needle under pressure is all. No reason it won't needle correctly on suction unless something is wrong.
Old 04-10-2016, 05:21 AM
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RickP
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Pond Skipper,
Yes backplate pressure line pressurizes the outside of the bladder.
I've read a ton of posts on breaking these engines in and my impression was that it would take this long. This project has been going on for several months. I'd take it outside once or twice a weekend and wake up the neighbors!!

I'll buy a resetting tool and go through the engine once more.

The time before last I gave a tank full of 35% nitro a try and it actually seemed like it performed worse, way too lean and I couldn't richen it up enough so I stopped it. I don't know if I want to fool with the 35% nitro anymore. If I do should I put another head gasket in?

How many turns out should I be starting with with this NV?

Much Thanks
Rick
Old 04-10-2016, 08:35 AM
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I would go with GCB and check the three little holes in the venturi, and use filtered fuel. Without checking, I would start at about 6 turns with the KK needle on pressure. Maybe the bladder is too thick, and it is impairing the pressure. Try it on straight suction on a different tank, and I would guess it would work fine. Unless it is a bored venturi.( that is about the easiest performance improvement, at the expense of being more tempermental with needle settings, and backplate pressure problems like air leaks)
Old 04-10-2016, 09:48 AM
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I totally disassembled the motor, I did find some "gunk" in the distribution ring around where the three holes are located. I ordered a piston rod resetting tool, I'll wait till I have that back and clean it all up and have another go at it. Thanks guys!!
RP
Old 04-10-2016, 10:41 AM
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Good, how much play was in the ball socket there should only be a hair after you reset.
Old 04-10-2016, 11:10 AM
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I do not understand the pressure tap being used to pressurize the outside of the bladder

A fuel tubing bladder requires no addition support

A balloon tank perhaps....confused

First a TeeDee 049 does not really need any break in and will run at 85% of full rpm right out of the box...two or three flights at 25% nitro and 20 % castor will get these precision engines near peak power.... 35% to 60% nitro is usable but just destroys the piston and rod

To run pressure bladder, do yourself a favor and make sure about the NVA...stock Cox part was NOT fine thread...and second favor either plug the pressure tap or use it as designed to pressurize a HARD tank

Texas timers sells the 128TPI NVAs http://www.texastimers.com/

Make up a true pressure bladder...see Texas Timers excellent "how to" on this subject

Check out other sources if you please such as CoreHouse ( Phil Cartier), good bladder stuff, or Doug Galbreath ( nelson heads and plugs)

Cox TeeDees are exceedingly difficult to start and fly with a hard tank but thousands of folks figured out how in the 60s~70s....(I never learned how to hold my mouth properly and gave up...bladders work for full tank no flame out flying)

Most bestest method for reliable full tank flight with the TeeDee was KK ( Kirn Kraft) or other Fine thread NVA and pressure bladder using surgical or fuel tubing

I own 21 TeeDee/Medallions and have 7 in service on 1/2a combat wings

2 inches of bladder, fittings, pinch off device, 25% Sig 1/2a fuel...Galbreath head and Nelson plug....all start second flip hot or cold
Old 04-10-2016, 01:52 PM
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Bladder in the hard tank gets steady air pressure pressing on the bladder for an even fuel flow.
If the bladder material is too thick it may not get enough pressure build up to squeeze down the bladder.

A fine thread NV help get closer to peak rpm without risk of a lean run no matter what the fuel delivery method is.
High pressure setups thrive on a fine NV thread as small adjustments can make a big change.

I only use hard tanks and have and excellent results with easy starts and good idle.
All about proper prime and starting with a loaded fuel line. I like using clunk tanks even
on 1/2 oz tanks. After filling the tank and plugging the feed line to the carb I use a fuel bulb
and force fuel / air into the vent line it forces the feed line to load up removing any air bubbles.
Only takes minimum prime to start the engine and a loaded line keeps it running with no hiccups.

I only use spring starters for TD .010 and .020 and a 12v Hornet 1/2A starter for .049 thru .15 engines.
Old 04-28-2016, 04:10 PM
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I used to race 1/2-A pylon and never worried about breaking in a Tee-Dee, it was broken in with the first startup. To get better airflow through the engine, I removed the cylinder and lapped it (2000 grit wet/dry sandpaper on a FLAT surface...move in a figure 8 motion) until the ports were front/back instead of to the sides. Never used head shims, they reduce compression. Never used crank pressure. Best fuel system is pen bladder into a Kirn-Kraft needle-valve. Fill bladder with 1/2 oz fuel, clamp fuel line, attach glow starter, have partner hit engine with starter and release line clamp. Instant start up. 25000 rpm on Cox fuel with 5-3 prop.

Before learning about using bladder pressure for racing, I tried running on suction from a tank. The engine would start pretty well, but would die when the plane, an Ace Pacer, was hand-launched. With bladder pressure, that problem disappears.

Check rod/socket fit frequently and adjust it with the tool from Cox. It's a super simple ultra-powerful engine.
Old 05-09-2016, 08:51 AM
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Working in spurts here on this project. I reset the piston ball, it did not seem that bad to me, but I have no reference as to how bad is bad? How can you measure these things? Anyway I assembled the motor and fired it back up. I got a nice 17.2K with the set up above. I got a good adjustment on the needle and pretty happy with it, and from what I get above I seem to be doing well with those numbers on the bench. Now on to the other portion of this project.
Old 05-09-2016, 09:57 AM
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Good to hear you have it running but but but....What glow head type, prop and nitro content must have info in order to gauge a 17.2k rpm reading.
Old 05-09-2016, 10:53 AM
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Rick, ideally there is zero slop in the ball socket.
A barely perceptible amount of slop similar to the thickness of typing paper is OK.
The problem with trying for zero slop is developing a bind that has to be worked free.
It is possible to deform the piston slightly while performing the reset, so beware.
17,000 with a 6x3 is good enough to fly, have fun...!
Old 05-09-2016, 10:58 AM
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Originally Posted by Pond Skipper View Post
Good to hear you have it running but but but....What glow head type, prop and nitro content must have info in order to gauge a 17.2k rpm reading.
Cut and pasted from above:
Tee Dee .049
Two head shims
25% nitro
Back plate pressure fitting
3 oz bladder tank
fine thread NV (128 tpi?)
6x3 prop

Glow plug? I have no idea, it's a stock glow plug. Are there different types? all of mine look the same...
RP
Old 05-09-2016, 11:24 AM
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Yes there is the Low Compression Head and the High Compression Head and mild modifications over the
years that's the jest of it. The TD type glow plug will have a knurling ring around the top. The low compression
heads have no knurling marks just smooth on top. The TD High Compression head will give you a good jump
in rpm.

2 head shims with a stock glow plug and a 6x3 prop sounds about right with 25% nitro.
Did it run steady with the back plate pressure? Agree with Chuck you should fly it and
enjoy! It may loosen up a bit in the air and I would imagine up to 23k unloaded is possible.

Post a vid if you can = )

Last edited by Pond Skipper; 05-09-2016 at 11:29 AM.
Old 05-11-2016, 07:14 AM
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Originally Posted by Pond Skipper View Post
Yes there is the Low Compression Head and the High Compression Head and mild modifications over the
years that's the jest of it. The TD type glow plug will have a knurling ring around the top. The low compression
heads have no knurling marks just smooth on top. The TD High Compression head will give you a good jump
in rpm.

2 head shims with a stock glow plug and a 6x3 prop sounds about right with 25% nitro.
Did it run steady with the back plate pressure? Agree with Chuck you should fly it and
enjoy! It may loosen up a bit in the air and I would imagine up to 23k unloaded is possible.

Post a vid if you can = )
You mean like this? Is this one of each?
RP
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Old 05-11-2016, 08:47 AM
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Yes, the one with the knurled ring stamped on top is the higher compression head.
Compare chamber size, [side by side] to see the difference.
Old 05-14-2016, 06:58 PM
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Hi again,
Just remembered a couple more hop-ups we did on the Tee-Dees. We smoothed out the transfer ports, as there are still quite a few machining marks from the factory. The other thing we did was open up the venturi a little bit (don't ask how much, I don't remember.) so we'd get more air volume to mix with the high volume of 30-40% nitro fuel we were getting from the bladder pressure system. Just a few small enhancements made quite a difference. Good luck with the engine!
Old 05-23-2016, 09:48 AM
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Hi Guys,
Here a video of the final product. Looks like 3/4 of a pound of thrust is the most I can get out of it.
RP

https://youtu.be/dT9QDrz95sA
Old 05-23-2016, 11:27 AM
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You are not letting the tank vent?

Where is the vent for the bullet tank.. if up top as I imagine you wont get a steady run.
Looks like a looped line of fuel tubing plugged into both vent and fuel fill port?

7.5oz thrust not bad for a fan for initial early testing.

Last edited by Pond Skipper; 05-23-2016 at 11:37 AM.
Old 05-23-2016, 11:54 AM
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A guy who used to post here often JAPANMAN spent a lot of time playing with commercially available ducted fans. He had at least 1 really great thread about how he powered a scratch built, 1/2 A powered MIG fighter. As I recall, he ended up with a pretty decent performing combo after quite a lot of his own custom work and machinist level skill went into it.
Old 05-23-2016, 01:09 PM
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I think a TD .020 at 33k could make a nice lil screamer. 2.75in dia fan 3 blades 4P could see 100+
Old 05-23-2016, 01:15 PM
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Originally Posted by Pond Skipper View Post
I think a TD .020 at 33k could make a nice lil screamer. 2.75in dia fan 3 blades 4P could see 100+
The way it was explained to me, fans really need lots of rpm to replace reduction in diameter.
I would look at what the equivalent size / weight electric units need for RPM to produce adequate power and then decide if glow power is feasible.

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