Old Cox 049 will not hold RPM

The airplane you have is called the Delta Dart II Amazer put out by Midwest.
It is a bare bones trainer kit for first time C/L flyers that is pretty unique.
The youngster builds it himself almost like a scout project pinewood derby racer.
There is a duckbill balsa attachment that mounts where the engine goes so the first timer can "whip" the plane around with a 36" long 3/8 inch dowel attached the bell crank.
Once totally comfortable with spinning around and controlling ups and downs then the duckbill is removed and the plastic engine mount you have and engine are attached.
Add the control handle and the fun begins.
I guess the kits were sold to groups like Boy Scouts to introduce the hobby to new people.
I scored two such kits off eBay about 10 years ago for $14 each shipped.
Have never seen any show up since....
FWIW......Steve...

Cool looking little trainer:   Want one now?  

https://www.ebay.com/i/222099952569?chn=ps&ul_ref=https%253A%252F%252Frover.ebay.com%252Frover%252F1%252F711-117182-37290-0%252F2%253Fmpre%253Dhttps%25253A%25252F%25252Fwww.ebay.com%25252Fi%25252F222099952569%25253Fchn%25253Dps%2526itemid%253D222099952569%2526targetid%253D412958523344%2526device%253Dt%2526adtype%253Dpla%2526googleloc%253D9052681%2526poi%253D%2526campaignid%253D1057493165%2526adgroupid%253D54502406080%2526rlsatarget%253Dpla-412958523344%2526abcId%253D1133846%2526merchantid%253D6394584%2526gclid%253DEAIaIQobChMIr_vr_5XU2gIVg_hkCh0b1wmSEAkYECABEgJsdvD_BwE%2526srcrot%253D711-117182-37290-0%2526rvr_id%253D1509974615447%2526rvr_ts%253Dfa360d4c1620a866e6374a0cfff628ed


Whew what a link!

Good grief! There really is such a thing. I was going to answer that it's probably just a buncha' wood scraps someone turned into a plane, Lol. It looks like the perfect thing to re-train with. Plenty of wing and stab, and easy to fix in the field. Welcome to the forums.

Also, about the engine; the narrow venturi tube that extends from the tank and fits into the breather inlet in the backplate has a small round flat washer around its tip that can be easily lost, overlooked, or mistaken for crud. Some people use small o-rings in place of it, but be careful not to distort the backplate when tightening the 4 screws. A leak there will make the engine unruly, especially when the fuel level drops enough to uncover it.

I would definitely recommend following Ken's advice, disassemble and clean the internals before pulling your har out chasing phantom air leaks. I use lint free rags and 10 weight oil when rebuilding. Singer sewing machine oil at Walmart or most any craft store, or air tool oil is perfect for the job. They are probably both the same thing. It's clear oil with little or no solids or wax in it to gum up later.

It can be difficult hunting down air leaks on the engines with built-in tanks. You may be asking more questions as you rule out possibilities, so we'll help you knock it out, one thing at a time. And there are a gazillion threads about the same problem you are having, but don't let that stop you from asking. Parts can be found at www.coxengines.ca (that's Bernie). And also at www.exmodelengines.com (that's Matt).

Good luck,
Rusty

Back to CL wrote:

By the way, this old classy trainer that I have had for a decade. Flies well to retrain me. What airplane is this. I have no recollection.
Thanks in advance,

When "Steve" (66 Malibu) identified your model as the "Amazer" and described its functionality.. I knew that I had info on it somewhere. I had photocopied a few pages of a Dick Sarpolus book; "Building and Flying Control Line Model Aircraft"



Pages 52 and 53 contain some information on the model;

Thanks Roddie and Marleysky for the research and intel work you guys presented.
The more you know about something is always good.
I had bought those two kits off eBay to get two grandkids into the hobby.
Right after that I got a newly built Sig Dewey Bird with a new Baby Bee for about $25 and a jackpot deal on a newly built Sig Sky Ray, new metal back Black Widow, lines and handle, and a new Cox starter kit with fuel for $10 at the Perry swap meet !!!!!! Seriously, at the last table before going home, I saw the Sky Ray and the guy said you're the only guy to even look at it ,so you can have the whole works for $10 !!!!!! Bingo !!!!
Because of the two Sig planes, saw no need to build the Amazers.
I kind of the keep them as a reminder of what I missed all those years that I had bust it working!! HA !!
Thanks again...............

Thank you everyone for your support. Thanks for all the research on the airplane. I am just getting back to CL so am using this small Amazer to get rid of dizziness before I go to 1/2A Sig Skyray.

I am using fuel that has : Contains 25% Nitromethane, 55% Methanol,10% Synthetic Oil,10% Castor Oil. A regular 1/2A fuel only. Same bottle of fuel and my Cox Babe bee runs great, no issues.

Will re insert the screws at the back plate and can an JB Weld Drop at the end of the screw help stop the leak for further assurance? Or a drop of silicone latex? Will remove the NV and insert a small washer. Do you anyone of you have a photo of how the washer goes in instead of the spring? Jest plot it down?

Thanks again for all your support.

FWIW....
Before you attach the tank look at the back of the crankcase where the screw holes were drilled and tapped.
There will be ( about 100% chance) small burrs around the holes.
Lay a piece of 600 grit emery paper on a flat surface, add a drop of machine oil, and rub the back of the crankcase in a figure eight pattern a few times.
You can see and feel if the burrs are gone and then clean it up.
I would not use JB Weld on the screw tops to keep them in place. It is a bear to remove when you have to reset the rod and piston later.
I use a drop of silicone on each screw head.
On the needle valve you will need a small piece of fuel line to slip on after you put the #2 washer on first.
The fuel line becomes the seal and spring..
That's the way that seems to work best...
YMMV.....Steve.

Hi Steve,

Will do the Emery board process to deburr.
Regarding the fuel tube above the #2 washer. Same length as the spring I assume?
Sorry for asking such newbie questions, but much appreciated. Thanks

Be careful with the emery board in that it might lower part of the crankcase mating surface.....
Then you will have sure nuff vacuum leaks and a real bad run.
Cut the fuel tube about the same length or a little longer for a better seal.
Put the washer on the needle valve first and it will stop at the flange on the needle valve.
That flange was the spring keeper to maintain pressure to keep the needle valve from rotating when the engine is running. The washer is the retainer for the fuel tube.
Once you put the fuel tube on the needle valve carefully screw the needle valve clockwise until it stops turning.
Then trial and error turn counter clock wise about 2 turns to begin tuning when the engine starts.
Treat those parts as a jeweler not as a blacksmith and it all should work well.....
Steve............

Ron, is that a new production tank from Bernie?