Author Topic: COX TD 049 starting tips? (Read 1054 times)

Dennis Toth · « **on:** August 03, 2021, 01:45:48 PM »

Other than an electric starter what tips, techniques or methods do you find most effective for starting a TeeDee 049 on a small combat size prop?

Best, DennisT

john e. holliday · « **Reply #1 on:** August 03, 2021, 05:07:21 PM »

What type fuel system, Bladder or tank?

Tim Wescott · « **Reply #2 on:** August 03, 2021, 08:26:42 PM »

Isn't it kinda hard on the crankcases to use a starter on those?

Larry Renger · « **Reply #3 on:** August 03, 2021, 08:32:37 PM »

Not if it is a 1/2A starter.

For hand starting, be sure you have a good glowplug and hot battery, Start with 3 turns open on the needle and a light port prime. Should get a brief run on prime. Open the needle 1/4 turn and repeat. After a few attempts, you should have it running. After that keep the needle setting.

944_Jim · « **Reply #4 on:** August 03, 2021, 08:54:33 PM »

Wear a hard leather glove.

Sorry, someone had to say it.

Dave Hull · « **Reply #5 on:** August 03, 2021, 10:56:21 PM »

Obviously, they are harder to start with a toothpick prop. First, find out if you can reliably hand start it using a prop with more mass, maybe an APC with a six inch diameter or so. If you can't, then you are p!$$Ng in the wind thinking it is going to be worth the frustration starting out with a small combat prop. If you have trouble with the larger prop, then take a close look at the piston/cylinder fit. If it isn't snappy, it's going to be harder and the 1/2A starter makes sense.

The heavier prop will let you get the starting routine down, and provide a pretty close shot at the needle. The F2C guys do this all the time to get their diesels running and some heat into them. Then they swap props and make some finer tweaks. This is especially important if the engine has been apart or you have somehow lost the settings.

I totally agree with Larry on using a really good battery. I would also recommend that you use at least 25% nitro. Now there's going to be a bunch of guys who say they can run a Cox--any Cox--on 10% or 5% or no-nitro. Go ahead. Get flippy. Personally, I'd rather just start the thing and fly.

I guess what I'm saying is that I try to eat the elephant one bite at a time, so I don't choke on the whole leg.....

The Divot

BillP · « **Reply #6 on:** August 04, 2021, 03:13:35 PM »

25-35% nitro and stock spring or elec starter. Any 1/2a prop. High nitro is the best single answer to easy Cox 049 starting.

Tim Wescott · « **Reply #7 on:** August 04, 2021, 04:44:48 PM »

Quote from: Dave Hull on August 03, 2021, 10:56:21 PM

... Now there's going to be a bunch of guys who say they can run a Cox--any Cox--on 10% or 5% or no-nitro. Go ahead. Get flippy. Personally, I'd rather just start the thing and fly...

I have personally gotten reliable runs out of a Cox Reedie on 5% nitro -- by custom making a super high-compression head. No way can I get my other little engines to run on that stuff!

944_Jim · « **Reply #8 on:** August 25, 2021, 02:33:54 PM »

Quote from: Tim Wescott on August 04, 2021, 04:44:48 PM

I have personally gotten reliable runs out of a Cox Reedie on 5% nitro -- by custom making a super high-compression head.

Reliably enough to convert a good chunk to high(er) compression?

I have a bunch of stuff between .049-.15, and a Fox .35. I like the idea of a higher compression engine running the same stuff the Fox likes.

Could this work for reedies, Medallions, and a bunch of Norvels .061?

How much did you have to take off the head?

I assume you did it on a lathe.

Thanks.

Dave Hull · « **Reply #9 on:** August 25, 2021, 07:43:13 PM »

Be aware that Cox .049 engines are stressed pretty well for sport flying. But once you start trying to make a lot more power, or try to set them up for high compression--presumably to run anemic fuel--you are going to see more broken pieces. The cranks usually go first. That's why you can have fun converting one to diesel, but will likely bust the crank before you get your full quota of fun.... The Davis Diesel cranks tried to incorporate sufficient strength to handle this, and have gone thru multiple iterations. Some of the older ones were not dimensionally compatible with the cases in the axial dimension(s) which caused problems. Others, in an attempt to maximize the web strength (a known failure area) were not counterbalanced. The most recent ones I purchased had most (all?) of these issues mitigated, but best to know what you are trying to accomplish when you buy your bits and pieces.

Dave

Mike Scholtes · « **Reply #10 on:** August 26, 2021, 04:36:19 PM »

I have 3 TeeDee .049s in FF use, including the one I bought in 1962. Still in use. I have started them hundreds of times on a small electric starter made for half-A engines, never by hand on the 5-2 props in use. FF suppliers like Texas Timers may still sell the starter, or Hobby King maybe. High nitro like 25-35% or even more helps light the fire. If using a bladder, keep tubing pinched with one of the devices made for this until you are ready to start. Remove the pinch device but hold tubing pinched between fingers. Put the spinner (even the stock TeeDee spinner works) against starter cone, hit the starter button (most FF guys use a foot switch), and burp the fuel line till engine catches, then let go of tubing when it is running. Be ready to re-pinch tubing if engine quits or you will fill engine with fuel. I strongly suggest one of the replacement cylinder heads that take a Nelson plug or a conventional glow plug. As you can surmise this process would be impossible without a starter motor and a remote switch operated by some body part other than your finger.

Mike Scholtes · « **Reply #11 on:** August 26, 2021, 04:48:32 PM »

Forgot to add that the electric starter needs to be mounted atop a post that is solidly mounted to something like your flight box. You press the spinner into the fairly immovable starter cone, then step on the switch to start the engine turning, then release the pinched fuel tubing. I suppose this routine would be possible with a helper holding the plane or the starter, but the timing and feel needed is tricky if two people's reactions are involved. These little engines can be really dangerous. My Cyclon .049 turns 36,000 rpm on a carbon FF prop, not something to trifle with. Get an electric starter. You won't hurt the engine.

kevin king · « **Reply #12 on:** August 27, 2021, 12:50:15 AM »

What would be " a hot battery" for the Tee Dee 049? Do you mean an rc setup type that you can raise and lower the amps?

Dennis Toth · « **Reply #13 on:** August 27, 2021, 07:14:20 AM »

Mike,
Do you have a photo of the start switch set-up and a wire diagram, parts list? Back in the day we had rather big starter boxes for speed (photo from 1962, John Kukon speed starter box), a bit impractical with today's starters. Do you no of an insert that fits the 1/2A Hornet starter (by Sullivan) that will fit the Tee Dee 049 original nose cone?

Best, DennisT

Mike Scholtes · « **Reply #14 on:** August 27, 2021, 10:25:13 PM »

It's not a work of engineering genius, mechanical or electrical, but it has worked for 30 years. The leads connect to the 12V power panel; the foot button completes the circuit and juices the starter. The wing nuts at bottom of 2x2 post anchor the post to the vertical end of the flight box.

I have seen the hand-crank starters in speed in the 1950s (dim memory) but a little bulky to lug into the middle of a field for FF!

Dennis Toth · « **Reply #15 on:** August 28, 2021, 10:17:10 AM »

Interesting design, what type of foot switch did you use? How did you keep the starter start strips engaged? I was thinking of a simple C bracket that would clamp to a test box I have then use hose clamps to hold the starter to the bracket with something to hold down the connection strips and run one lead to the foot switch.

Best, DennisT

Mike Scholtes · « **Reply #16 on:** August 28, 2021, 01:10:12 PM »

The starter is held to the top of the post with a large hose clamp, through a hole drilled through the post (hole not visible in picture). Also large rubber bands on hooks shown in pic. This is just a Rube Goldberg thing that happens to work, maybe not best design ever. Switch is a press-to-connect that springs back to "off" when pressure is released. I put the red box on ground in a convenient location where I can step on the switch with right foot. Keep in mind this is for FF where you are holding the fuselage with one hand and managing the fuel tubing/bladder with other. CL routine may differ, esp with a helper. You push the spinner into the starter cone, step on switch, and engine usually starts instantly. Sorry, don't have any info about the Sullivan starter.

Mike Scholtes · « **Reply #17 on:** August 28, 2021, 01:20:46 PM »

Forgot to add (again) that since the starter has a push-to-start button, I loop a large rubber band over the starter to keep it pressed in "on" position. The foot switch in effect is just a remote push button. The starter won't run unless foot switch is pressed.

Tim Wescott · « **Reply #18 on:** August 28, 2021, 05:00:10 PM »

Quote from: 944_Jim on August 25, 2021, 02:33:54 PM

Reliably enough to convert a good chunk to high(er) compression?

Well... You'd have to try. The engine ended up on a crap airframe, so it's hard to say. And the fact that there's a known correlation between engine compression and the amount of nitro you need, and that no one else has done this, suggests that there's something about it that maybe doesn't work for all engines all the time.

Quote from: 944_Jim on August 25, 2021, 02:33:54 PM

I have a bunch of stuff between .049-.15, and a Fox .35. I like the idea of a higher compression engine running the same stuff the Fox likes.

Could this work for reedies, Medallions, and a bunch of Norvels .061?

How much did you have to take off the head?

I assume you did it on a lathe.

I actually made a custom head (on a lathe) that used a regular glow plug. I made it crazy-high compression, then adjusted the compression with shims until it actually ran right. (I did find out that an overcompressed reed-valve engine will pretty much run through a tank while bouncing its prop back and forth against the compression bump -- that's not useful information, but hey, now it's known!).

If I were going to do it again I'd use a turbo plug like in this article.

Or check with this guy to see if he makes high-compression heads. I suspect the answer is no, but hey -- you can ask.

So experimentation may be in order. I would expect that if you did find it practical, you'd need to plan on shimming the head for different weather conditions, and that may be more of a bother than just getting 25% nitro fuel.

Tim Wescott · « **Reply #19 on:** August 28, 2021, 05:02:54 PM »

Quote from: Dennis Toth on August 27, 2021, 07:14:20 AM

Mike,
Do you have a photo of the start switch set-up and a wire diagram, parts list? Back in the day we had rather big starter boxes for speed (photo from 1962, John Kukon speed starter box), a bit impractical with today's starters. Do you no of an insert that fits the 1/2A Hornet starter (by Sullivan) that will fit the Tee Dee 049 original nose cone?

Best, DennisT

You can 3D print elastomer (i.e., rubbery stuff). So it shouldn't be hard to get something made up if you can find someone with a 3D printer and some will.

I don't know how the 3D printable elastomer holds up to glow fuel, though.