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

How many head shims are you using?

Thanks Brad. Will check if I have the exact same props hou mentioned. I use 1 shim only but suspect that the cylinder does not bottom out. However I will look at the exact position through the cylinder top before and after the Kyosho is added.

Yes good to know just where the cylinder is at, 1 shim is good to make up for the variance.
With the plug off you can check the deck height with one shim.

Cox Mark II .15 RC with Profi .15 Tuned Pipe:

Painting a picture / with a clean flow, leak free manifold and proper
sealed single exhaust port could become the first TD RC to bust 200 mph!

Kamtechnik Nelson Plug Turbo Plug Adapters has been tested and now
the web site has been updated with new product slots opening up soon
to have stock in hand perhaps by this week.

https://kamtechnik.com/shop/





Kamtechnik Nelson Plug adapter test / Piped 1996 Killer Bee .049
APC 4.6x3 prop / best static 22,609 / 10.4oz thrust / 64 mph PS
.111hp - 82w / if this prop is used to fly it will unload and stage
on the pipe likely boost to unload at 27.5 -28k / 80mph PS
For speed a 4.4x4.5N  120 mph PS expected.

All the .020 turbo heads sold out already totally missed out on the first batch.

I guess the out of stock on his website means the stock has not been filled yet...Greg wrote in a post here that he just starts the 020 and 090 turbo head serial production after the prototypes tested well.

Now that the magic dust has been applied to the Cox.020 displacement Greg
is going into mill time and is willing  to sort out an adapter replacement for the VA .020.
Extra power will likely be had by following the current .020 chamber design.
Best rpm sticking to two shims with the APC 4.2x2 each engine will be a
bit different in shim count older engines will only need 1 shim.

Some of my findings during testing:
Compression volume is not the only factor once a given ratio is found,
chamber shape improves and squeaks out further power. The number of
samples tested and those modified helped to sniff out which direction to
go keeping perseverance alive and suitable use of the prototypes around
14 in total. The cox 4.5x2 is a real challenge to hit 19k some engine out
of the box can hit that number, 20k static is possible with further efforts
to improve the timing / deck height of the piston. The crank window can
be sharpened on the rotation side to improve intake.

What mattered beyond compression ratio,
-Proximity of the element to piston face
-Transition shape from shim line to plug face
-Charge concentration across a given percentage of the piston face / what best serves the load of the 4.5x2
-Improvements by sound distinction / variances the adapter shape makes / loud, hollow thru peaky sharp notes.
-Full spread vs narrow concentration of force pressure to piston face, horn, cone and bowl shape diameters all
have their attributes. Providing enough spread to counter the load leaves the rest of blast rate to focus on ramping
up best possible time / rpm.


I am looking forward to testing speed props with the product adapter.
So far with a previous prototype modified for suitable use:




This is J4 the one that has finally brought out the last bit of rpm out of the test
engine. It has been widely used for all the prototypes. A fresh piston cylinder
with good seal will likely hit 19k + Shown with a Cox grey 4.5x2

Thank you Gents looks like the ball is rolling again!
I was given 4 items in the last package sent to finalize, 3 down one more to test.

Some good ole goo control to help keep .020 projects cleaner and it adds a bit of
back pressure for RC carbs. Fit is important for a leak free seal.  I have documented
results with this engine prop and will see what the difference is in rpm with only
the manifold header add.



Some positive tank pressure:

[/url

Oct 27, 2020
Kamtechnik Header / Manifold .020 Prototype Testing
Cox TD .020 APC 4.2x2N
Open exhaust: 22.2k rpm 42 mph PS
Manifold and header: 19.9k rpm 38 mph PS
OS P4 Turbo Plug
-Reduces piercing tone
-Adds back pressure for RC carbs
-Single exhaust goo control  
-Can use a pressure tap

Bump to an old thread, 1/2A nut I ran across this thread looking for a cool airplane to build for an 049. I have been into RC since the early 2000s and started out with a cox 049 to pull my glider up. Never played with them much since then, but I recently came across some more 049s and would like to build something around them. Your speedsters here are too cool, I love fast planes - keeps me from getting bored (I used to do pylon racing). Just amazing how fast these little ones you've built are. Most of the discussion here has been the 020 and 010, do you have a specific design you recommend for 049? Would like to leverage your expertise a bit if possible to build something fast and cool... looks like you're using 1/32 ply for the fuse and solid balsa wings? Thanks for any direction you can give, I'll keep digging through posts on here...

Thank you Elijah, yes as described in this thread with photos and drawings led to the Nano design for
.010 / .020 /.049 /.09 / .15 engines as my easy method to achieve top speeds.  
Another thread here:
https://www.rcgroups.com/forums/showthread.php?2684743-Speed-Planes-010-to-15-Size-Engines
https://www.rcgroups.com/forums/thumbgallery.php?t=2684743&do=threadgallery


NANO X 3ch Speed Plane Cox Tee Dee .051 -149.7 mph pitch speed Tuned Pipe 4.3 x 5.5N




 

Thanks for the thread links, I think I've found most the stuff I need. Drew the templates out in AutoCAD tonight, gonna order some of the airfoil balsa. What do you make the tail feathers out of, 1/8" balsa? Also what prop do you like to start with? I notice you mostly use the tee dee style cox engines, the ones I have here have the integral fuel tank. I remember the teedee style had more power but hopefully this will still make it go pretty good

Yes 1/8th if you sculpt in a airfoil. APC 4.2 x 4 will be a good test prop.

.020 version was reproduced by a Jordan Kearney- from New Zealand




Jordan Kearney- from New Zealand
Published on Feb 8, 2018

Cox Pee Wee .020
Cox 4.5x4 prop "for an .049" tested
5.5cc internal tank 20% nitro /20% castor


Notes from Jordan:
This one does has a spruce leading edge and it’s covered in heavy ultracote, still it
comes in at 3.42 oz dry + a 5.5cc tank. I use digital high voltage servos so I can run
them directly from a 2s 180mah lipo. Also the fuse is 1/16 quarter grain balsa with
1/64 ply doubled along the sides from the engine mount to just past the trailing edge.

 

Again, thanks for the info. Got the fuse sides cut out and the tail feathers made up. How do you do the hinges? I was thinking to do some real light glass cloth to make a skin hinge. Maybe monokote alone is enough for a hinge?

Nice little racer for an .020.
I would loose sight of that plane so fast it would still have 7/8 of a full tank after the crash.

I simply cover the bottom with up elevator then cover the top with down elevator.
Once done you have full movement no gaps easy clean up after a run.

Thank you FlipStart!

Micro Nano TD .010

Last TD .010 project 2.2oz / 28 Sq. in.

21.6sq. in. 16" span is possible @ est. 1.8oz RTF

That is so cool! Where did you find the transparent propeller? And what speed have you achieved with this latest iteration?

Thank you Jim,

I have been collecting gear for the next TD .010 project.
Testing HQ T series props etc. Will post build pics and flight
vid per the norm when it happens. These props are not for
straight line speeds / good sport flying with more speed than
a stock prop. 2.56x4 gets down wind over 140 mph pitch
speed with the last Nano design. The 4cc tank dia. is less
than the previous 7cc tank used with the last project. Less
weight and allows a smaller fuselage.




 

Link to CEF member Tobaiies build thread.
https://www.coxengineforum.com/t16251-cox-peewee-micro-speeder#212143

Nano X comparison in scale to a Q-200 1/2A plane.