RE: modifications to an 049  
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All Forums >> RC Airplanes >> "1/2 A" & "1/8 A" airplanes >> RE: modifications to an 049
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RE: modifications to an 049 - 9/5/2007 3:30:58 AM   
500 lb. koolaid man



Posts: 1052
Joined: 5/22/2006
From: Palm Harbor, FL, USA
Status: online 		I just realized that what I said earlier barely made sense at all, I was in a rush when I typed that. I basically told you it's too late to break it in that way now then asked you if it was too late. But thanks, what you said made what I said make sense. Well thanks for the info, I'll be sure to break in my next .049(If and when I get one) that way.


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RE: modifications to an 049 - 9/5/2007 4:29:48 AM   
combatpigg



Posts: 10104
Joined: 11/22/2003
From: arlington, WA, USA
Status: online 		You always want to tune from the rich side, these engines will run very rich with the glow plug connected and give you time to find peak, then back off to a steady, but slightly rich setting for break in.
A single AA cell won't last very long, especially if that uninsulated clip makes contact between the center post and "ground".

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Led Zeppelin is NOT "old fogie" music.

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       Post #: 52

RE: modifications to an 049 - 9/5/2007 5:20:42 AM   
David Ingham


 

Posts: 166
Joined: 8/22/2007
From: , CA, USA
Status: offline 		I had to use a torch a couple of times recently. Besides softening hardened caster oil, it expands whichever piece you point it at, and aluminum expands more than steel, so it gets the cylinder off the crank case even if you heat evenly. To loosen the head, you need to get the cylinder hot before the head or cool the head.

The mixture when flying depends a lot on whether it has subinduction. That is, if the exhaust port extends down so far that there is a gap below the piston when it is full up, then air comes in at high speed and leans the mixture. This naturally doesn't work well with mufflers. TDs and some older Babe Bees have subinduction. Subinduction is better for speed, and without is better for stunt because the model's speed is more constant.

Most all the parts are interchangeable between the reedies, and many between the reedies and the TDs. So go to http://www.coxmodels.com/products.asp?dept=85 and get some Sure Starts in case you wear out the pistons and cylinders on the engines you have. They are $7 each! Maybe this puts a new light on the diesel thing. So what if the rod bends, you spent a good fraction of $7 on gasoline driving to the flying field. So take wrenches and Sure Starts to the field to avoid wasting the gas for a trip home.

< Message edited by David Ingham -- 9/5/2007 5:29:54 AM >

(in reply to combatpigg)
       Post #: 53

RE: modifications to an 049 - 9/8/2007 2:41:22 AM   
500 lb. koolaid man



Posts: 1052
Joined: 5/22/2006
From: Palm Harbor, FL, USA
Status: online 		I finished the exhaust throttle ring that I've been working on for the past few days. I'll test it tomorrow. And I started working on a 2 D cell battery pack.






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I have too many projects already... but I always find more.

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       Post #: 54

RE: modifications to an 049 - 9/8/2007 3:20:59 PM   
Yuu


 

Posts: 358
Joined: 9/4/2006
From: Shawano, WI, USA
Status: offline 		Looks like that battery set-up will work...just don't put the batteries in series...3 volts will 'smoke' the glow plug filement. I bought a pair of 2000 mAh D cell Ni-Cads from Radio Smack... 2 for $7.00. I put them on the little 50 mAh charges for a week, and they last a month at the field. Then back on the charger for another week. And I used a Cox glow-clip....but took it apart and soldered a 20" lamp cord to the copper instead of that tiny thin wire. I put cereal box cardboard between the copper to insulate them from eachother and wrapped the mess in a couple plastic zip ties. No voltage drop there!! The other end is a plastic battery box for one cell, small bolts in each end for Good contacts, wrap the box outside with a couple rubber bands to keep the bolts Tight to the battery, and alligator clips to complete the circut. If you can't find a Cox clip, look for one of those old style TV antenna clips... plastic and work like a spring clothespin. Pound a dull nail in the top clip to make a little dent to 'crown' over the glow plug top, and bend the lower end so it clips to the Cox cylinder, and you're good to go. You just can't count the number of gadgets that people make for this little hobby !! Keep 'em flying !!

(in reply to 500 lb. koolaid man)
       Post #: 55

RE: modifications to an 049 - 9/8/2007 7:40:57 PM   
500 lb. koolaid man



Posts: 1052
Joined: 5/22/2006
From: Palm Harbor, FL, USA
Status: online 		Yuu, thanks for the info, very good idea what you did

The throttle ring failed to work. It makes a fairly tight fit too, enough to where the engines vibration wont move it around yet not on too tight since a paper clip turns it. I think the exhaust just "slides around the ring". I still have one more thing to try though, and that's make the ring tighter be removing the arm then re-soldering it on with the ring off the engine rather than on. The engine was smoking when I killed it, that would just be fuel on the head, correct?

Here's a video of the ring, not working as planned.
http://www.youtube.com/watch?v=Gt7Zmwocw6U

Any advice on making the ring work would be appreciated, thanks.


_____________________________

I have too many projects already... but I always find more.

(in reply to Yuu)
       Post #: 56

RE: modifications to an 049 - 9/9/2007 4:18:20 PM   
Yuu


 

Posts: 358
Joined: 9/4/2006
From: Shawano, WI, USA
Status: offline 		I made one of those little throttle rings for the TD and the product engine. Both work fine. Good transition too. But I do not have near as much 'open' for the exhaust as you have. In fact, the engines run pretty much full open...until the exhaust is closed to about 1/32" open space, and it only needs to be on ONE side. Slop between the cylinder and the exhaust ring may be the problem. I made a vertical cut all the way through the ring and bent the ring a little smaller on another piece of cylindrical metal [bolt], then put it on the cylinder and clamped it tight with a vise-gripper pliars and soldered another small piece over the saw cut. Just a little sanding inside with sandpaper on a stick will adjust the ID to fit the cylinder and turn easily. Perhaps a saw cut in the ring...upward at, say, a 30 degree angle, would let the exhaust out at a little more Gradually for better control. I saw one of your photos where the screws mounting the engine were not tight... I've found the backplate must be tight to the firewall or test stand to get good engine operation.

(in reply to 500 lb. koolaid man)
       Post #: 57

RE: modifications to an 049 - 9/9/2007 4:52:14 PM   
500 lb. koolaid man



Posts: 1052
Joined: 5/22/2006
From: Palm Harbor, FL, USA
Status: online 		Thanks Yuu. I guess my first flaw was having too much of a gap and having a gap on both sides, the thought of doing that came from thinking that the exhaust on these engines were not made too big, and they need to be that big for full power. The second flaw must be that the ring is obviously too loose(slop) since when it's fully closed(no exhaust gap at all) all it does is reduces noise and exhaust, not RPM.

I am shooting for a very hard task and thats trying to be able to hook a exhaust throttle ring up to a servo and have idle and WOT and everything in between, doing this with a micro servo from min. to max. movement. I still haven't figured a way to do this yet, any ideas? It sounds like yours work very well but they're either full throttle or idle at 1/32" gap.

Thanks.


_____________________________

I have too many projects already... but I always find more.

(in reply to Yuu)
       Post #: 58

RE: modifications to an 049 - 9/9/2007 5:12:31 PM   
combatpigg



Posts: 10104
Joined: 11/22/2003
From: arlington, WA, USA
Status: online 		I've never tried doing an exhaust throttle, but I've heard that the fit has to be so precise that the O.D. of the cylinder gets trued up before the exhaust ring is fitted. There was another type of design where the cylinder is sealed off with a high temp silicone boot and the actual throttle valve was a slide trombone looking thing made out of brass tubing.

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Led Zeppelin is NOT "old fogie" music.

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       Post #: 59

RE: modifications to an 049 - 9/10/2007 6:22:20 PM   
Yuu


 

Posts: 358
Joined: 9/4/2006
From: Shawano, WI, USA
Status: offline 		koolAid...Search these pages and find the thread where Dickeybird made a throttle for the TD...only skip the venturi modification with your SS or BB. "Idle"...is actually more like 6800 to 7500 RPM for these little guys, NOT the 500 to 700 RPM like the bigger engines. You're on the right track..don't give up.
Pigg...perhaps the grinding on the outside of the cylinder was just to 'fit' the available ID of the tube used to make the Acce throttle ring...or to convince the average hobbist he had to BUY the parts, not make it himself. The 'silicone boot' type muffler with the 'trombone' snout ...I saw something like that on the other group where the guy took two brass tubes, fitting one inside the other, drilled a hole through both [one side only] and inserted it into the choke tube of the SureStart for a throttle, controlled by a servo hooked to a paper clip soldered to the outer tube. There were three 'c' rings to keep the tubes in line and still turn easily to let the air in through the two holes, or turn the outer tube and close off part of the hole to slow it down. The end of the inside tube was plugged, and the assembly was siliconed into the choke tube. Only problem was that there was no data on the degree of throttle, or RPM, or laughter from the field when they saw a SureStart with a submarine 'snorkle' on the front. I saw your thread on the 'thrust' machine you built, and you had lots of data about the results.



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       Post #: 60

RE: modifications to an 049 - 9/10/2007 6:46:18 PM   
ZoomZoom-RCU



Posts: 473
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		Intersting you should mention that combatpigg, I currently have a slide trombone style intake throttle....ie..positioned over the choke tube. Its made from a simple plastic barbed plumbing tee, and a wooden dowel. Its going into an auto gyro that I'm working on. I'll let you guys know if it works well, cause building it took me literally a few minutes, and if it works well, I will recommend it.

ZZ.

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RE: modifications to an 049 - 9/11/2007 4:19:39 AM   
500 lb. koolaid man



Posts: 1052
Joined: 5/22/2006
From: Palm Harbor, FL, USA
Status: online 		Thanks for the help everyone, the last few posts have been extra helpful.

I have plenty of ideas on my head to get full function RPM from min to max, the basic concept is make the hole only big enough to allow full RPM, and no extra "still full RPM" like a lot of these homemade ones turn out to be(not meaning to be rude). Maybe something similar to a skinny line(what the hole for the exhaust would look like) then have it go from fully open to sliding shut, left with a small gap allowing for idle. I hope that made sense.

ZoomZoom-RCU, be sure to get back to us on that one. I have an idea using a golf tee in the air intake if that works, or I'll do what you did. Can you post a pic of what you made?(and results if you've got a chance to test it yet) I'd really like to see it. Thanks.


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I have too many projects already... but I always find more.

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RE: modifications to an 049 - 9/11/2007 4:36:03 AM   
combatpigg



Posts: 10104
Joined: 11/22/2003
From: arlington, WA, USA
Status: online 		500#KM, I don't know if having an object rattling around in a vibrating intake is a good idea over the long haul. A barrel valve located on the engine side of the spraybar has been proven to be the way to go for these little engines. Choking the engine above the spraybar isn't as effective, that's the way they did it before Ford came out with the Model T.

_____________________________

Led Zeppelin is NOT "old fogie" music.

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       Post #: 63

RE: modifications to an 049 - 9/11/2007 2:18:32 PM   
ZoomZoom-RCU



Posts: 473
Joined: 6/30/2002
From: Louisa, VA, USA
Status: offline 		I'll be sure to let you know how it goes Koolaid man, and if I can get a pic done soon, I will post it shortly. Combattpig I'm sure you are likely correct that this may not be terribly efficient. But whats the harm in trying. My concern right now is that a wooden dowel may shrink or swell in the tube in which it slides to open and close the air flow. I may have to change this out for a metallic one, and lube it with some vaseline or such. In essence it is very similar to a drum type carb, its just a linear action, not a torque based one. I guess we'll see. Fingers crossed.

ZZ.

_____________________________

PAY NO ATTENTION TO THE MAN BEHIND THE CURTAIN!

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       Post #: 64

RE: modifications to an 049 - 9/11/2007 2:32:36 PM   
combatpigg



Posts: 10104
Joined: 11/22/2003
From: arlington, WA, USA
Status: online 		ZZ, I think ACE sold a tapered plastic plunger that was coupled to a servo linkage rod with a hunk of soft tubing. It must have worked at least well enough for them to package it. I always felt like my reedies were just 50 rpm shy of not being airworthy and my models already 3 ozs over what they should weigh, so I never tried it.

_____________________________

Led Zeppelin is NOT "old fogie" music.

(in reply to ZoomZoom-RCU)
       Post #: 65