Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Yes maybe the most catchy looking COX plane ever made.
Similar in its proportions  to my favorit balsa plane I built last year the Cosmic Wind ( see my avatar)

Bought the following to build up a wood version. The size could be reduce some for better
flying 1/2A or increase for more engine or left alone as is for .49 through .10 engines.
I have a OS .26 Surpass that would fly a 36" span version quite well. As you see it the
span is currently 24" x 6" x 3.25"

I will post the templates for everything if you want to build a exact RC version of your
favorite Cox racer.  

M-D Building Products 49985 Contour Gauge



Inside check not a drop of fuel ever. One on ebay bid up to $356 mint too crazy money.
The landing gear was never snapped into place. The Killer Bee would make this sucker move out.




Here is a later version called the Cox Super Sport II

Thank you, Brad. I am looking forward to following your build thread.

Check if your engine has a 049 cylinder...mine, for some strange reason, came NIB with a 051 thin wall cylinder without the top fin milled for the wrench. I remember having the trouble of removing it once, after I added a COX muffler covering the exhaust ports thus with no access to them with the wrench.

But that was a helluva engine, too bad I lost it, a real relic, in the Lil Roughneck..aka Lil Lostneck, see below..

Mine has a no wrench top too on the cylinder. It is not thin walled,
engine has SPI. The piston does not have a ring around the lower
portion of the cylinder so is not a .051. Came with a low compression
plug. A fine 120 TPI NV screen on the intake. I would have to take it
apart again to read the stamped number on the cylinder. I tried to
see with a magnifying glass in the typical locations no luck. I would
use my second spare Killer Bee to pull the plane around if I fly it.
If I buy another one that's not as mint as this one I will fly it.
This one being rare in mint condition I will not fly it.

I fully agree these collector items are relics of an era long gone, and I would also preserve it...I assume it should have a No 1 cylinder (that should have 2 bypass flutes and 0 boosters in it, visible by just removing the glow head) ..the weaker No2 cylinder would not have been sufficient to fly this typically sports/fast plane so I expect a No1 cylinder with 2 bypasses..

When I first received mine for Christmas being 11yrs old the plane seemed big to me
then and thought the engine was a marvel for it's size to fly the plane.
The plane weight is 16.05oz certainly doable for flying.

Greg Doe Quote:
"I recall seeing one of these Cox Super Sport Trainers in the 70's converted to RC.
Can't remember who did it, but I think it was either Jerry Nelson, or Ed Sweeney?"

With today's low weight RC gear this one could fly quite well converted with a 3mm carbon
tube at the CG under the wing to support RC flying. I say that because the wing is two seperate
panels. If no landing gear grass landings would be reasonable. Alas would have to have a lesser
quality one worth risking to fly.

I tested the header assembly bit too much restriction but need
exhaust deflection so cut up another Sportwerks header pipe
as shown this should have just enough back pressure for the
fuel tank. Prefer the cleaner set up for speed anyways.

That Fuji engine looks gorgeous, I could not look it up on sceptreflight site listing engine tests...how does it compare to a TD051?

sceptreflight is limited by old magazine articles so older engines.
This engine first came popular back around 2006
I swapped out the head for my more narrow one for speed.
Originally was using a round head for extra cooling during the summer.

Fuji throttles well and makes more power / speed see below:



Fuji .05 with header pipe /  idle / throttle test
3 ch / 12.2 oz RTF / 148 mph on a tuned pipe.
36,747 rpm unloaded



Fuji .05 / Profi .8cc Tuned Pipe
Static: HQ Prop 4x4.5  / Idle 9.3k rpm  / 28,746 rpm / 122.4 mph
9.6oz thrust / .198hp / 147.71w

Cox TD .050 / Profi Tuned Pipe / 25,193 Static - HQ Prop 4 x 4.5
Static 7.3 oz thrust / .132 hp / 99w / 107.3 mph

Need to bench test the engine with this longer header pipe see how it does.

Thanks Brad,

how do you tune in your pipe, you calculate the wavelength and measure the overall pipe length together with the silicone extension, or, just empirically i.e. pushing/pulling the pipe inside the extension until you hit the wave resonance/max speed?

I still have my Profi pipe waiting for its use, tried it but never hit the resonance speed..

When bench testing you can use a smaller prop to get on the pipe
when ready to fly you can prop up some as the unloaded rpm will also
get on the pipe. I was able to fly with a 5x4.5 and get on the pipe for
speed the 4x4.5 was still getting top numbers with the DART.
With the lower weight and size Nano III a 4.4x5 would be better.

.05 car engine Fuji or a Sportwerks engine:
160 deg timing so center of piston to reflection zone varies on opinion
always best to find the average rpm spread to select unloaded state
with any given props selection I will us a 4x5NE / 137 mph at 29k

- 1675(wave speed) x 160(timing) ÷ 9.5 (pipe length) = 28.21k rpm
- 1675(wave speed) x 160(timing) ÷ 8.5 (pipe length) = 31.53K rpm


28.87k rpm average of course you can extend the pipe when setting up
the coupler with a section of aluminum tube within the silicon tube should
you wish to run more diameter and less pitch.

- 1675(wave speed) x 160(timing) ÷ 11 (pipe length) = 24.36k rpm
Some say 1650 wave speed is better to use with full wave pipes - if so than 24k rpm.

http://www.bolly.com.au/book/images/Image54.gif

http://www.bolly.com.au/book/Book.ph...er=6&Section=3

http://www.bolly.com.au/book/Book.ph...er=6&Section=4

Here is another vid of the NANO the first test run with the modified APC 4.22 x 5.5
1440P HD

Thank you Brad I will save the formalae for my reference and tests in Spring. I will aim at the 24k resonance because I only have stock props that run with a TD in that range.

How often do you reset the balljoint after these runs around 28k? The COX manuals advise not to exceed 24k.

I checked the ball joint after all the runs and bench test it was still in good shape
with minimum play. The static output with the last prop was 20,370 rpm it unloaded
to 26,647 rpm the low weight / drag plane seems to do well not stressing the engine.
+ 6,277 rpm Remember to set the static rpm lower so it unloads in your owners manuals
safe zone for max rpm. The question is do they mean max static 24k or max unloaded state
how is anyone ever to know? What I do know is what has been working when used with
clean low weight planes really that's the only advise I can provide. Heavy plane with a 6x3 prop
will surely cause faster wear, crank to snap or con rod to snap. Heavy props with thick airfoils will too.
Careful use of the design application will allow flying with various types of planes of all sizes really just
need to watch the prop load.

Good news is Matt says he is waiting on final design for a aluminum fuel
tank for the TD .020 for those who don't want to use isolated nylon fuel tanks.

EXModelEngines wrote:

Hoping to finalize a design for an aluminum fuel tank on the 020 Tee Dee soon.

Matt

I just seen that from Matt and got me to pop in over here and see if any news ,, Is Ex having a Back plate made or a Alum. tank /back plate replacement ?

balogh wrote:Thank you Brad I will save the formalae for my reference and tests in Spring. I will aim at the 24k resonance because I only have stock props that run with a TD in that range.

How often do you reset the balljoint after these runs around 28k? The COX manuals advise not to exceed 24k.

I don't know how the rpm is/was measured but if an audio tach is used you then also have to correct for the doppler effect. For a plane travelling at around 200km/h the doppler effect is about 20%. So a reading of 28000rpm (as read with an audio tach on an approaching fast plane) is "only" about 23300rpm for the engine, and thereby safe, according to the advice from COX.

Hi Eric, I don't know.

Well if its a fuel tank as he says thats going to add some weight !?!?

EXModelEngines wrote: Looks great guys! Hoping to finalize a design for an aluminum fuel tank on the 020 Tee Dee soon. Matt wrote:

Yes true Eric  

I have a laser tach good for checking my audio app which compensates
for the Doppler effect also can use wav. scope software which also
compensates for the Doppler effect. Can also use your ear which also
has a mind of it's own.








AmpAbuser
Published on Feb 10, 2018
NANO III / 9oz / 28" span / APC 4.22x5.5
Best pass 26,647 rpm / 139 mph prop speed
Static 20,370 rpm / 1oz fuel / 25% nitro / 20 castor
With speed the sound follows behind the plane in the vid.
Checked all passes found the best per posted vid:
Per Audio RPM Gauge 26,647
Per Prop Calc 139 mph
Per Doppler Wav. Scope software 136 mph / 219 Kp/h

Also this new vid was added last night.  

APC 4.22 x 5.5
9oz RTF / 28" span / best static read 20,370 rpm
+ 6,277 rpm unloaded in the air best pass 26,647

Then there' the Lil Speedy busting 30k music to my ears!


AmpAbuser
Published on May 7, 2016

TD .049 /SPI / Throttle Sleeve Ports Allow SPI function / Prop 4.1 x 4.1N / 30% Nitro
Static 24,790 rpm / 7.4oz thrust / .127hp / 94.74w / 96.2 mph / 6.19oz RTF
Unloaded 30,492 best on Vid 1 / 118.4 mph per prop calc.
Doppler reading has it at 118mph per pass at 1:47mins into the vid.
Hard tank no pressure tap. 3.7g servos. Cox low compression plug.
3mins 20sec of run time on 15cc tank. 16.5"x4" span wing 66sq. in.
The is very small for 1/2A and very light at 6.19oz a real handful to
keep up with major heart thumper the Nano is smooth larger in size
easy to fly in comparison.

1/2A Nut wrote:
I have a laser tach good for checking my audio app which compensates
for the Doppler

How does the audio app know and compensate for the speed of the airplane?
Are you using the sound from an onboard camera?

Last summer you contacted the owner of that app who designed the software
to compensate for the Doppler effect do you remember what you he said? You
posted a his shared response. Off to work for now have fun guys enjoy the
high speed vids.

1/2A Nut wrote:Last summer you contacted the owner of that app who designed the software
to compensate for the Doppler effect do you remember what you he said? You
posted a his shared response. Off to work for now have fun guys enjoy the
high speed vids.

Nope, I have not contacted the owner of that app.
Have you ever tried with an onboard camera for a comparison?