Cursory break in test with a new engine / muffler and the new backplate now with a extended footing.
Nothing more, you can't compare break in results you know that. This is early bird info for me to retain.

With the same single engine selected:
I already have done my testing and posting of results with the common Cox 4.5x2 and the Cox 4x2.5 comparisons
made with the stock glow plug info provided to Greg. Multiple adapters tested till I passed one for production your
months behind the work done. It's Greg's call to use the data or not on his site.

My youtube has some of the tests other info was kept secret for a reason.

Some allowances made on a few threads.
https://www.coxengineforum.com/t1161...ght=backplates
https://www.coxengineforum.com/t9540...highlight=nano

Originally Posted by 1/2A Nut

Cursory break in test with a new engine and muffler and the new backplate now with a extended footing to work with the muffler.
Nothing more, you can't compare break in results you know that. This is early bird info for me to retain.

With the same single engine selected:
I already have done my testing and posting of results with the common Cox 4.5x2 and the Cox 4x2.5 comparisons
made with the stock glow plug info provided to Greg. Multiple adapters tested till I passed one for production your
months behind the work done. It's Greg's call to use the data or not on his site.

My youtube has some of the tests other info was kept secret for a reason.

Some allowances made on a few threads.
https://www.coxengineforum.com/t1161...ght=backplates
https://www.coxengineforum.com/t9540...highlight=nano

Soo.... if you have say, the stock prop and plug RPM for a Gmark .03 and the rpm after switching heads, why wouldn’t you post them together rather than expect people to dig thru the prolific posts you make to get info that would matter to them?

Doesn’t matter-do your thing.

Best thing to do is go enjoy your parts and find out for yourself.
Anything that Greg puts on his site will bring performance, that is
the goal.

New old stock engine break in results with turbo plug adapter.
These G Marks take a good amount of break in time to loosen up
this one has 2oz fuel heat cycled prior to early bird reading.

Needs a pressure tap on the muffler, has proved to increase rpm.
Compression held up well after engine stop. After cool down and
a bit of after run oil the piston / cylinder fit feels great. I buffed
up the muffler for a bit of bling.

Tested with the common Cox 4D x 2.5P
45 mph pitch speed / 62 mph PS with APC 4.2x4N
Was fun to run this one up will be messing with it more soon.

G-Mark .030 / Turbo Plug / Gen 3 Adapter (1 min 24 sec)

Published on Jun 28, 2019
APC 4.2x2 @ 24,547 / 47 mph prop pitch speed / 8.5oz thrust.
.066hp - 49.24W / could not read idle it was under 7k as the
low end setting on the rpm gauge was set at 7k good engine!
25% nitro 20% oil recommend 23% all castor with the GMark.
OS RP4 plug / RPM Gauge app was reset read 5,329 rpm idle.

Summary of tests:
Open Exhaust Turbo Plug OS RP7
Cox 4.5x2 / 21,237
Cox 4x2.5 / 20,914
Cox 4.2x2 / 24,547
Stock plug
4.5x2 / 17,689
Stock plug with Muffler
4.5x2 / 17,720

Salvage effort for one of the prototypes, digressed results in stock form.
Will do a single shim bench test to see what's possible should get some
good use with this engine.

Recent built up engine using a new old stock cylinder / piston set came with a custom throttle sleeve.
Looks like one of Steve's Select Hobbies old offerings he also had .010 assemblies / now all sold out.
All aluminum lower end from Ex Model Engines, Kamtechnik low weight backplate rounds out this engine.

Spotted some of Andy W work from RCU wee little RC carbs for the TD .010.

Update the engine made reasonable power during break in not sure what the peak
is as of yet. The plug mod has helped nearly 19k with a 4.2x2N needs a few tanks
of fuel yet and will have to hit 21k to be a winner. Just added 2 additional head shims
to see if it loosen up some of that extra rpm for the next test sometime soon.

Best so far TD .020 RC carb with another modified adapter P4 plug:
6.7oz thrust / 37w / 22,206 rpm 42 mph pitch speed game changer
performance for the .020. No exhaust restriction unlike this one being
tested with the throttle sleeve.

Update added two more shims to jump to the other side of coin it panned
out the engine made massive thrust for a TD .020 / 6.34oz with a APC 4.2x2N
I think 3 shims is a bit much two should bust 22k based on what is known with
the previous RC carbed engine shown in the last post.

Next salvage effort prototype D has been given the same treatment with
a 1/2" ball grind flush to plug face. Yes I have a collection of TD .020's this
one has a fresh new low weight backplate the cylinder design is the last gen TD.
Compression is set with 1 shim feels good so moving forward with a test.
Will try two shims if need be should be a winner following the same fix.
OS P4 and modified Cox 4.5x2 with swept tips.

Ok looks like the 1/2" ball grind is making consistency with the second engine
and the 2nd salvaged prototype "Adapter D":

Cox Grey 4.5x2
Static average 17,199 rpm / 5.3 oz thrust / 33 mph pitch speed
17,280 to 320 tweaked NV
17.2k /.030hp - 22w

25.2g with spinner less prop.

1st. Modified TD .09 / Valentine Turbo Plug Adapter / Throttle Sleeve
See first photo for reference:

Static MA 5.5x4.5 / 17.3k / .153hp - 112w / 12.34oz thrust / 74 mph pitch speed
Unloaded 24,467 / 104 mph pitch speed / rich flight cooled in the air.
May of hit 109 with a good NV

Static APC 4.75x5.5E / 18,010 rpm / .117hp - 87w / 7.4oz thrust / 94 mph pitch speed
Unloaded 24,492 rpm / 128 mph pitch speed / good NV

Kirn Kraft 128 TPI NV and Bored Venturi:
Static APC 5.25x6.25E / 17.1k rpm / .170hp - 125w / 10.22oz thrust / 101 mph pitch speed
Unloaded 23,821 rpm / 141 mph pitch speed / good NV


2nd .09 engine has undergone conversion efforts for RC use.
See second photo for reference:

Stock Cox High Compression Head / Modified Muffler / Pressure Tap
Fora NN 6.25x3.25 prop
Static 20,914 rpm / .33hp - 240w / 31oz thrust / 64 mph pitch speed

Note venting was limited as shown in the photo the engine is loud indoors
so wanted to keep my ears protected. Prop for thrust has increased power
data at the expense of pitch speed. Pressure tap improved the top end.
Stock muffler test / no pressure static 18,733 rpm window was closed
all exhaust went out the header.

2nd engine has now undergone further conversion efforts.
See third photo for reference will bench this version next.

Update the snarling Kraken .09 put out the juice.

Even with an exhaust diverter to reduce the noise
it was no joy to the ears. Idle down in the low 6k
was the only moment of appreciation other than
the lovely boost in power indoors lol.


Kamtechnik turbo plug adapter, OS P4
Did not tweak the NV much seemed thirsty without
a pressure tap and ramped up the rpm with ease.

Fora 6.25 x 3.25
Static 20,752 singing steady / 30oz - 1.9lbs thrust
.319hp - 234w / 64 mph pitch speed

2 head shims used / 1 head shim with the Cox plug.
Would go with 3 head shims with 7" or 8" props.
A 5x6 for speed should do well with 2 shims.
MA 5.5x4 can go with 1 shim

With less restriction and a pressure tap no doubt another 600 rpm and if open exhaust more like 1k could be had.
I will know more when it's ran at the flying field. As predicted the head adapter performance is just as good as what
was found with the Queen Bee.

The previous bench test with the Fora prop using the less restricted Cox muffler and pressure tap gave the engine
an advantage over today's test. I was not wanting to ring my ears again with that setup. The make shift lid was leaking
oil as expected but enough to cap off the noise. Here again a good sealed manifold / header would make this a clean
running engine enjoyable to hear run. Took off the goo trap, I hope Greg is willing to repeat what's on the Nano X for
the .020 .049 .09 and .15

Timo out of Germany was inspired by the TD .09 DART and made one similar for himself.
You can google the word Taschenflitzer (Pocket racer) and the kit comes up. 5 months ago
he messaged me on my youtube channel and we chatted on CEF about his build / setup.
He wants to put a pipe on the engine.

I have been meaning to post his vid results so here it is enjoy!

German site with DXF zip file Doug could kit this one.
http://www.rc-network.de/forum/showt...henflitzer-zip

2009/01 Taschenflitzer.zip DXF data set.
http://www.verein.rc-network.de/frae...henflitzer.zip

Wingspan: 800mm
Length: 630mm
Weight: 250g

Big thread on it here the original 46 pages:
http://www.rc-network.de/forum/showt...Taschenflitzer

Taschenflitzer mit Cox 09 ! (1 min 20 sec)

Timo Katemann

Plane called a Taschenflitzer (Pocket Racer) with Cox 09!
800mm span / 31.5" (same as my DART)
I have asked him what prop he ended up with, can get
pitch speed from there. In the vid during start up looks
like a black carbon prop.

This is an all balsa fuselage so builds out light with the framed up
wing quite impressive with potential / can't go wrong with a carbon
rod.


To compare:

DART -TD .09 / APC 5.25x6.25E / 143 mph best pass (3 min 26 sec)

DART -TD .09
Best level pass 143mph / per prop calc / APC 5.25x6.25E
Wavescope: 232.07 kmh / 144.2mph /down wind / 21,960rpm
The reading was taken at 1.52mins into the vid. Temp 96F
Static 17.1k rpm at launch / 9.52oz / 101mph / .167hp / 125w
30% nitro / 20% castor / 31.5 inches 106 Sq. In. wing / 11.7 oz RT

Top tip,
The slop in the none oxide threads for the bullet spinners always cause a slight shift in the crank threads and
the spinner / the dual shift adds up. With larger displacements not such a big deal, however with the smaller
one's every bit helps to remove vibration to gain rpm! Additionally in this case the extra thread length helps
with the thicker APC prop hubs. Another big bonus is the stud never gets stuck in the crank, can always be
backed out with a hex wrench.

Here the fit is so snug I had to oil the threads prior to assembly
and drive it in with the hex wrench while holding the thrust plate.
The bullet spinner threads needed oil too, this is as centered as
one can get.

Killer Pee Wizzer .020

- Carbon blend horse shoe backplate
- Large bore intake
- 128 TPI Needle valve
- Tee Dee Cylinder / Piston set
- Mylar performance reed valve
- Valentine bullet spinner
- Kamtechnik Turbo Plug adapter
- OS P4 plug

Cox Killer Pee Wee .020 / 19,864 rpm / 3.8 x 3 / Turbo Plug (1 min 13 sec)

Sep 25, 2019

Modified Cox Pee Wee into a Killer Pee Wee.
3.8 x 3 / Peak 19,864 rpm / 57 mph pitch speed / .26w / 3.6 oz thrust
TD cylinder / piston set / Kamtechnik turbo plug adapter / large intake venturi
Carbon blend horse shoe style backplate. / Valentine bullet spinner / 25% nitro
128 TPI needle valve / 3 head shims

Will set up a throttle sleeve and drop down to 1 shim for max rpm next.
Peak did push past 20k with three shims I have reduced to 1 shim and added
a throttle sleeve hope to maintain or exceed on the next bench test.

1 shim was the ticket, with the throttle sleeve in the way it still made much better numbers + 970 rpm.

Cox Killer Pee Wee .020 / 3.8x3 prop / Peak 20,833 rpm with throttle (0 min 26 sec)

Cox Killer Pee Wee / 3.8x3 prop / Peak 20,833 rpm with throttle
4oz thrust / 59 mph pitch speed / .040hp - 29w
1 head shim / turbo plug adapter / 25% nitro

The size of the plug kills me...Lol....