Keil Kraft Phantom Scratch build from start to flying.

Here is a nicer shot with the colour how it really looks.
Woody.

Woody,
That is some beautiful wood work there! I wish I had the patience to conquer an instrument...I'd love to play a Ukie. My mother gave me my maternal grandfather's ukelalie. I'm afraid it is too old/brittle to have professionally re-worked.

The spraybar/needle in your Medallion .09 happens to also have been used on the Medallion .049/.051. You are correct that a circlip belongs on it to retain it. But the spring/needle will also help keep it in place. I bought a couple 8n case I came across a Medallion without one, but I misplaced the puny things!

I've over-propped a few engines along the way, and I get 3 second runs as the engine runs on the slobbering prime. But the engine never gets up over prop-load to be able to pull fuel and keep running. I suspect your prop is too tall a pitch.

Look left, just under "more latest topics," and find "instruction sheets." There is one for the .09, and I think you'll see a 7x4 may have been specified for the engine. Maybe even 8x4. Try that engine again with a lower-pitched prop and some reading up in the instructions. Oh, and try known good fuel...that one is heartburn for sure, unless that same fuel runs another small engine as is.

Outstanding ukulele craftsmanship, Woody, looks like it was made by a professional ukulele manufacturing company.  

Regarding props, please see note at the end of the Medallion Instructions introduction:



Props recommended by Cox:

I was actually on the thought train that the prop is just too big for the engine.
I am used to diesels so expect it to swing no probs.
I have a 6" normally fitted to an 049 so I will try that.
Yes..FUEL...my 049 fires up on 10% nitro and runs perfect. I have added Nitro to the mix for the Medallion but she still does not want to know.
I will try with a smaller prop.
There is not a lot if compression to speak of.
I will report back .
Glad you like my Uke.
Woody

Well blow me down.
The little sucker went like the clappers with a 6x3.
I got 1/2 a minutes good run till the tank ran out.
It sure screams and really loud.
I think I need ear defenders.
Thanks to this forum and you guys putting in your bits I got her running.
I am not used to Cox motors so need time to get to know them.
So the verdict is this ..
They do run okay even when tired...its a matter of getting them started.
The spray bar hole needs to face downwards.
The prop needs to be smaller than larger.
They need the correct fuel ( although I have not tried her on 10% nitro yet)
They need a positive user attitude and with sympathy!!!
They GO when they want to.
They are termed " She" because you never know what the heck they are going to do but when they do it, it fills our desires.
Fuel tubing!!!!
Any takes on this?
I am using really oversized tubing as it is all I can muster ATM.
I have a feeling that the tubing should be small OD and an ID that is a pig to get onto the fuel nipple and fuel tank tubes.
I think my fuel tubing is far too big.
Where can I get the right tubing?
A hearty thanks guys for pulling me through this.
This forum is the best.
Woody has been pleased and very happy.
Sorry....you will hopefully get used to my humour!

Woody wrote:Well blow me down.
The little sucker went like the clappers with a 6x3.
I got 1/2 a minutes good run till the tank ran out.
It sure screams and really loud.
I think I need ear defenders.
Thanks to this forum and you guys putting in your bits I got her running.
I am not used to Cox motors so need time to get to know them.
So the verdict is this ..
They do run okay even when tired...its a matter of getting them started.
The spray bar hole needs to face downwards.
The prop needs to be smaller than larger.
They need the correct fuel ( although I have not tried her on 10% nitro yet)
They need a positive user attitude and with sympathy!!!
They GO when they want to.
They are termed " She" because you never know what the heck they are going to do but when they do it, it fills our desires.
Fuel tubing!!!!
Any takes on this?
I am using really oversized tubing as it is all I can muster ATM.
I have a feeling that the tubing should be small OD and an ID that is a pig to get onto the fuel nipple and fuel tank tubes.
I think my fuel tubing is far too big.
Where can I get the right tubing?
A hearty thanks guys for pulling me through this.
This forum is the best.
Woody has been pleased and very happy.
Sorry....you will hopefully get used to my humour!

There you go!!

Oldenginerod wrote:

Woody wrote:Well blow me down.
The little sucker went like the clappers with a 6x3.
I got 1/2 a minutes good run till the tank ran out.
It sure screams and really loud.
I think I need ear defenders.
Thanks to this forum and you guys putting in your bits I got her running.
I am not used to Cox motors so need time to get to know them.
So the verdict is this ..
They do run okay even when tired...its a matter of getting them started.
The spray bar hole needs to face downwards.
The prop needs to be smaller than larger.
They need the correct fuel ( although I have not tried her on 10% nitro yet)
They need a positive user attitude and with sympathy!!!
They GO when they want to.
They are termed " She" because you never know what the heck they are going to do but when they do it, it fills our desires.
Fuel tubing!!!!
Any takes on this?
I am using really oversized tubing as it is all I can muster ATM.
I have a feeling that the tubing should be small OD and an ID that is a pig to get onto the fuel nipple and fuel tank tubes.
I think my fuel tubing is far too big.
Where can I get the right tubing?
A hearty thanks guys for pulling me through this.
This forum is the best.
Woody has been pleased and very happy.
Sorry....you will hopefully get used to my humour!

There you go!!

But I cannot run it anymore.
The glow head has gone.
There has always got to be something to steal my thunder.
Okay...so it works.
I think the most sensible approach is to order a glow head that takes normal glow plugs.
I need a Cox spanner for 09 , an 09 piston reset tool, some proper tubing and maybe shims, gaskets etc so I will order the lot in one go from Canada and save a lot on postage.
There is a weird type washer thing behind the propeller nut thingey.
I do not know what its made of but it reduces crankshaft end float.
If someone can tell me what its called, i can order a few up.
I think I need to make a bigger fuel tank as the fuel went pretty rapidly.
Is this normal ? ( I mean are 09 Medallions know to use a lot of fuel)?

Woody, your prop choice of 6x3 is light. As seen in the chart, the 6x4 is the smallest recommended prop. On the other end, the 8x4 is the largest which I would never choose to use myself as it's too large. Basing your fuel use from the 6x3 prop would be incorrect as it's using more fuel due to higher rpm's. In addition, basing your time from a test stand is also incorrect. The plane is going to run leaner in the air thus also increasing fuel mileage. Your initial prop choice of 7x6 wasn't so far off in terms of diameter, the pitch was excessive. The Cox .09 is one of those engines with limited prop choices in my opinion. The 7" is the max in my opinion  and the 6x3 is too light for it leaving limited choices in between. My experience is strictly with the TD and not so much the Medallion as I felt it was very under powered. I fly control line only. The TD is easier to tame down the power vs trying to extract blood from a stone using the Medallion. I like the Medallions quite a bit and I found them to be terrific choices for twin engine planes. If you want anemic engines to work well, install them on a twin and they do beautiful.


         As for using standard plugs, this is fine if you can afford to lose 1000 rpm's. The Medallion is not a powerhouse. It's a mediocre sport engine so if your looking to achieve similar power if not more, you want to use a turbo plug head which is provided by Kamtechnik.com. Mind you that plugs are way up in price and turbo plugs are generally on the average $12 and more a piece. The turbo adapter is almost $14. All minus shipping of course. Keep in mind though, higher nitro percentages are also quite a bit harder on glow plugs which are almost not to mention extinct for the .09.

       Fuel tubing as long as it fits the spraybar snugly  really shouldn't be a issue. Obviously, too large of tubing doesn't fit the spraybar barb or tank vent tubes tightly will provide air leaks thus poor fuel draw.  Fuel tubing length is more important, keep it as short as possible. Problems that occur with the Medallion are as Jim mentioned, clogged spraybar. Blowing through it of course to insure it's free is good. Pushing the proper sized wire through it is better. Placing a finger over the venturi and pulling a choke through it is critical. Make certain, it draws fuel all the way up to the spraybar prior to starting. Air leaks develop under the plastic body and around the spraybar. Make certain the collet holding the carb body on is snug. Also check to see if the plastic developed cracks around it as they will do so with age.  You can audibly hear some leaks so carefully lend a ear when choking. A loose backplate can also cause fuel draw issues and also a feeling of poor compression.
       
         Poor compression in Cox engine can be caused by poorly seated glow plugs. Either the head gaskets are compressed or the head itself isn't exactly flat or it's just loose. On a piece of glass place some fine sandpaper 400-600 grit on top of the glass and lap the mating surface of the plug on it. Clean it up and reinstall with NEW head gaskets. They will come loose at first but when snugged again, they have a tendency to stay fixed. If indeed the compression is on the lower side of the spectrum, use higher nitro to try and regain back some lost power.

        Directly in front of the nose of the case and behind the drive washer is the thrust washer. It can be made of phenolic or stainless.

        I also can't stress enough of the importance of using a good starter battery. Most problematic starts can be linked to this. Therefore, properly sized lead wires and new batteries are a must. The longer the clip is attached, the hotter the head gets, the more resistance and it all equates to a non start. These engines can easily be flooded and this hampers starting further as the plug is already taxied.

For your interest.  Foam R/C Phantom.

https://www.vintagemodelcompany.com/how-to-build-the-vintage-foam-phantom-online-instructions.html

Oldenginerod wrote:For your interest.  Foam R/C Phantom.

https://www.vintagemodelcompany.com/how-to-build-the-vintage-foam-phantom-online-instructions.html

Well I guess it will sort out my engine problems!!

Sounds like you have made good forward progress on the engine Woody… I think half the fun of a project like this is getting the engine to run right…. Even to tune it to how you want it to perform…. You’re getting some great advice…. There’s also lot’s of other good tidbits sprinkled throughout the forum that can be helpful….

Thanks for sharing the ukulele… I bet it sounds sweet …. Love the tiger figure on the back…Looks like some violin background ….. Light is good on stringed instruments, Helps a lot with tone and volume…

I built my guitar in ‘07….




Here it is getting some the tone bars glued in….The rods are sprung between the two surfaces to press the wood into the lower table that is recessed to shape the top of the guitar…. It leaves the top in tension…,Wood is then carved away on the ends of the struts until it reaches the desired pitch…



I would not have attempted something like this if it had not been for building a lot of model airplanes as a kid…. To me they were/are relative to many other things we experience

That is a beautiful classical guitar.
I bet it sounds as beautiful as it looks .
How long did it take you to make it!?
Wonderful craftsmanship.
You are beilliantly clever.

I think Ken is spot on, speaking from personal experiences. Usually, I find engine reviews useful as they give a more quantitative view often substantiating personal observations, plus helps one to initially select prop sizes for their particular application.

Interestingly enough, I went back to the non-R/C standard Medallion instruction set. The R/C instructions Prop RPM table I showed in my previous post in this thread have all the same values as the standard Medallion, so those RPM numbers are inflated. Unfortunately, Cox copied the same values, so we have no typical RPMs for the muffled version. Equally frustrating is that the only source I know, Sceptre Flight has only one engine review (and, this is not a complaint as the proprietor has done an outstanding job in capturing as many engine reviews as he had available to him). This is the Medallion .09 R/C review by Peter Chinn's from 1967 Aeromodeller. He only states idle RPMs for the various props without any maximum RPM figures.

Sometimes poor performance data is not revealed because the company manufacturing the product also advertises in the magazine. One doesn't like biting the hand that feeds them.

However on a positive note, @Kim showed that his Medallion .15 R/C with older style throttle indeed can perform during his short lived stay at SMALL in Arkansas.

I can understand the diesel point of view if this is what one is most familiar with. They are definitely torque engines.

From http://sceptreflight.com/Model%20Engine%20Tests/Taipan%201.5.html - Taipan 1.5 cc (.09)

Also interestingly enough, the Medallion .09 R/C w/exhaust throttle muffler instructions specified Cox Super Power Fuel. Pointed out in this thread, it had 15% nitro.
https://www.coxengineforum.com/t10183-original-super-power-fuel-formula#128833

Later 1988 date with Leroy Cox no longer in control, I gather that some liberality was taken not necessarily the most optimal for performance leaving the user to figure out (15% nitro fuel and numbers for unmuffled Medallion), so they could sell fuel and engines.

Woody,
A ready source of fuel line is as close as back surgery or a colonoscopy...wink at the nurse as she discards the IV tube. Ask gently if she'll remove the sharps and leave the tubes. Is it great stuff? Nope. Does it work? Yep!

Regarding your glowhead, hang on to it. If you have access to a drill press or lathe, you can convert your existing one to take a glow plug. I know a how-to thread exists somewhere...I think RCUniverse. I know the process has been linked to here before.

Congrats on the engine run!

Thank you Woody, About 180 hrs over the course of a year… I kept a note book in case I ever want to build another…. Maybe a spruce top one day..

944_Jim wrote:Woody,
A ready source of fuel line is as close as back surgery or a colonoscopy...wink at the nurse as she discards the IV tube. Ask gently if she'll remove the sharps and leave the tubes. Is it great stuff? Nope. Does it work? Yep!

Regarding your glowhead, hang on to it. If you have access to a drill press or lathe, you can convert your existing one to take a glow plug. I know a how-to thread exists somewhere...I think RCUniverse. I know the process has been linked to here before.

Congrats on the engine run!

Thats a good idea Jim.
I will register for a colonoscopy just to get the tubes!