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Cox Engine of The Month
November-2017
MauricioB's

"Cox Tee Dee .010"



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DART- TD .09

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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Jun 21, 2016 10:01 am

The APC company has done a good job with material selection. Tough but able to snap a blade in a hard nose down crash
great for saving engines. The prop hub is simalar to IC hubs suitable for the engine. I installed a phenolic washer as part of the
upgrades and will use a 1/2A Hornet starter on 12v / it's a 500 size can motor with and 1/8" shaft.





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Happy Re: DART- TD .09

Post  balogh on Tue Jun 21, 2016 12:03 pm

I also read on its user manual that the electric prop may break under the cyclic load of internal combustion engines and may snap unexpectedly. They are designed for the more stationary load of electric motors.
So be cautious not to stand in its rotation plane.
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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Jun 21, 2016 2:49 pm

That's all old old news to me having numerous hours of flight experience testing
modifying and learning vs manufactures protocol disclaimers which are very true
for larger IC engines the risk factor goes up. Thus far I have elect. prop use with
up to .12 size engines that as a general rule of thumb for me to be max IC size.

I have had hundreds of flights with various types and brands. Thus far no prop has failed
with the smaller IC engines through good design, material selection and modification. I
custom cut them to suit my needs every time a prop blade is reduced in size it in turns
makes them that much more able to handle the IC load
s.

With electric speed props some are much better made and way stronger then a Cox prop
as an example. Today's high powered electrics are changing prop designs and materials.



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Happy Re: DART- TD .09

Post  1/2A Nut on Thu Jun 23, 2016 9:26 am

Done ready to maiden flight the DART- TD .09 this weekend with a MA 5.5 x 4.5

Completed weight ready for fuel 11.9oz.

A light weight version could be done without the ply fuselage but I wanted mine to last.
I think its possible to hit 10.5 oz. RTF with all balsa build up.




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Happy Re: DART- TD .09

Post  1/2A Nut on Fri Jun 24, 2016 12:38 am





Published on Jun 23, 2016
6,400 to 7,400 range is possible, engine run up prior to
maiden flight with some rich break in time. Has rear back
plate pressure tap and bored venturi from Kustom Kraftsmanship.
Valentine turbo plug adapter with OS RP6 (med) turbo plug.
Master Airscrew 5.5x4.5 / two shims..




Too late for full throttle but also in break in mode, thus far accelerates like the small ones with a throttle sleeve.
The large venturi has no problem keeping up with the pressure tap. Hope to see 3 min flights. 1.4oz tank.
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jun 27, 2016 1:52 am

DART-TD.09

Thus far 128 mph stock APC 4.75x5.5E / 24,489 rpm unloaded best pass

Master Airscrew 5.5x4.5 Unloaded 24,467 / 104 mph (APC E props work better)

Weather was bad but managed some test flights this weekend.

Unlike the smaller engines screaming there guts out NANO's, Lil Speedy, Skorch's, the DART
gets it's speed on from the .09's torque and a high pitched props, Note the speed of the
second pass 3:15 mins. into the vid. The engine chugs along snapping and popping while
the plane is smoking fast. Started to rain didn't want water mixed into the venturi so had
to cut and run..

I do plan to get the engine up to scream mode the rich runs for break in time.
All the same its already fast. A carbon APC 5.5x6.5CE cut down to 4.5x6.5 will
be the prop to beat should do 145+


https://www.youtube.com/watch?v=KON-q5wPSSU













TD .010 / .020 /.049 / .09 Fleet of speedy planes.



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Happy Re: DART- TD .09

Post  1/2A Nut on Sat Jul 02, 2016 11:13 pm

https://www.youtube.com/watch?v=BqrjoTlrm3E



Published on Jul 2, 2016

DART -TD .09 / APC 5.25x6.25E
Best pass level 23,156 rpm /143mph / per prop calc
Temp 96F (16,975 rpm at launch) 30% nitro


Ok with wavescope: 232.07 kmh / 144.2mph / going down wind gave it an edge per the norm.
The reading was taken at 1.52mins into the vid.

Out of all the vids online for TD .09's this one is so fast there is nothing that even relates.



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Happy Re: DART- TD .09

Post  getback on Sun Jul 03, 2016 8:54 am

Way to Go !! Looks like RPMs are not the main issue with getting Fast results since around 17K was the turning , that pass didn't look no faster to ME than the Nanos but I could see it much better , I cant watch on large screen my computer want play it at real speed for some reason ? Well what's next Brad ?  4th of July Flag 4th of July Flag Eric Fireworks
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Happy Re: DART- TD .09

Post  batjac on Sun Jul 03, 2016 1:14 pm

Great job on the plane, and the fleet. Now you just need a TD .15 and your fleet is complete!

Not to be a criticiser, as I do things my own way when I build my own designs, but I see that you're using an APC 5.25x6.25E prop. 23K is well below the max RPM of 36K for that prop, but it IS an electric prop, not a nitro prop. I hope you're wearing eye protection when you're running that prop at high RPMs. I'd hate to see you get hurt if a blade separates while the engine is running.

The Rhymer Mark
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Happy Re: DART- TD .09

Post  1/2A Nut on Sun Jul 03, 2016 1:48 pm

Thank you gents!!

You can try play back at 720 HD if 1080 is causing lag should stop the lag. I will be doing up
a nice vid soon staying close to the cam, loops rolls yank and banks vertical climbs from idle etc.
Just wanted a speed check while I learn what the plane can do. It's a much bigger plane so the
speed can fool you with an engine not screaming like the smaller engines it's making good torque
to swing a 5.25x6.25

Yes 17k on the ground it not bad on the prop I have wiggle room to stress it further electric
guys are using over 300w at 30k plus. Here in Texas eye protection is a must lol  ye old
sun ball is rough!

For sure the TD .15 is up next can't wait to see what that baby can do I will use a MK II in
the end on the same plane the crowning finish of the TD Fleet. The larger DART is giving
me a look at how strong it is built with for .09 use and will help guide me to a solid TD .15
size plane. 35in span / 130 Sq. In wing should allow great glides. Goal is 170 mph.

I had Vultures flying over the field Sat. the DART's colors made them look for sure lol.






4th of July Flag Fireworks 4th of July Flag Fireworks 4th of July Flag Fireworks Small Cox Logo
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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Jul 12, 2016 3:03 pm

Alberto was fast on shipping out the Profi 1/2A tuned pipes the only company in the world selling 1/2A pipes!~





7.4mm ID vs 8mm ID for smooth fuel vapor / air transfer to the piston



Last few I tend to remove the coupler leaving a ring for the silicon coupler to grip with two zip ties on the header side and only needing one for the pipe side.



Much more information on my Profi pipe set up here with tuned pipe formula's, theory and my data.

http://www.rcgroups.com/forums/showpost.php?p=35238879&postcount=21

4th of July Flag Fireworks Fireworks Fireworks Fireworks Fireworks 4th of July Flag
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jul 18, 2016 3:32 am

After many flights with the DART -.09  its time to hang another
engine on the nose and see whats possible.



Published on Jul 18, 2016

Fuji .05 with header pipe / idle / throttle test
3 ch / 12.2 oz RTF will do a open exhaust flight
to see how the plane goes without the aid of
a Profi tuned pipe. Next vid shows whats possible.
Also want to try a TD .09 RC with pipe




Published on Jul 16, 2016

HQ Prop 4x4.5 / Idle 9.3k rpm / 28,746 rpm / 122.4 mph
.197hp / 147w / Pipe set up per Bolly Book at {8.8in / 31k}

Vrrrrooom vroooom wag wag Eyebrows
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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Jul 19, 2016 12:09 am

Update on the Fuji engine open exhaust 27,280 rpm with the goo extension on the manifold.
.168hp / 125w / 8.7oz thrust / 116 mph / anticipate 31k unloaded down wind 132 mph.
On the Profi pipe 28,746 + 1,466 rpm boost static, unloaded much more as it hits the MRP length.

Look forward to the field test next also did another test added a micro size pressure nipple on the header.
The pressure is enough to keep out bubbles in the line steady solid consistent fuel flow on the top end.




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Happy Re: DART- TD .09

Post  getback on Tue Jul 19, 2016 9:12 am

damn it man !! I like the way that thing revvvvvvs and the tuned pipes turn me own one of these days I will hit U up for that info on were to get the good stuff This Site Rocks! Eric
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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Jul 19, 2016 9:28 pm

Hi Eric,

Here is a link to how to get one of these engines up and running with a tuned pipe there are a few left.
It's been almost 2yrs since Alberto has had any on hand state side.

http://www.rcgroups.com/forums/showthread.php?t=2684743&page=2
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Happy Re: DART- TD .09

Post  1/2A Nut on Sun Jul 24, 2016 1:47 pm

https://www.youtube.com/watch?v=1D2sc-FtmKI&feature=youtu.be



Published on Jul 24, 2016
DART- Fuji .05 Profi Tuned Pipe 34,985 rpm Best pass 4x4.5prop
149 mph best pass per audio tach will doppler check next.
20% oil / 30% nitro / Temp 91F blazing sun made it seem hotter!
Static best peak 27,939 / 8.7oz / 134.3w / .180hp at launch 27.7k
1oz fuel tank almost all full throttle use gave 5:20 mins in total.

DART is a .09 size plane bit too big for optimum performance
but good enough to test engine output and run time.

https://www.youtube.com/watch?v=7IaQ4o_qXZ8


Update reviewing second vid Best pass 36,747 rpm 157mph per audio tach
With the right size plane the prop speed can be used to it's full advantage for now will
do a doppler check and see how fast it was really going more like 122 mph my guess will see..
If left on this plane the engine needs a 4.74x4.5 as the prop is slipping. 6.07mins. 1oz tank.
Also this ran very clean the plane didn't have oil spray all over
the wings and such the norm with a TD engine this time only
a very thin mist over the vertical stab and a hair bit on the horizontal
other than that butt clean all the way to the engine nada oil.

Update: Per Doppler wave analysis it was really going: 238 kmh / 147.89 mph best pass.
Down wind shallow dives gets the rpm / speed up prop is too small into the wind or when
pushed in steady banking turns. 8oz RTF plane and a 70sq. in wing with a thinner airfoil will
get the most out of the engine. I am the only person on the planet that has a actual use flying vid
of this engine tons of threads yapping about it and bench test vids but no flying vids. This is
ground breaking results folks here that spot read this thread are the first to witness. Will be
making a TD .15 plane next doing the testing per the norm for max speed then swap out the engine
to play with my collection such as a Cox Mark II. I plan to use a tuned pipe with that single port exhaust.
Small Cox Logo









Last edited by 1/2A Nut on Sun Jul 24, 2016 11:11 pm; edited 1 time in total
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Happy Re: DART- TD .09

Post  balogh on Sun Jul 24, 2016 8:29 pm

Brad,

amazed as always....how did you calculate the required pipe length for a peak output of the Fuji? Or just by the trial and error method??
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Happy Re: DART- TD .09

Post  1/2A Nut on Sun Jul 24, 2016 9:48 pm

Thank you here is a link that will show the process to set up the pipe it's really not hard to do.
By doing the math and bench testing there is very little time spent and really no error just improvements.

http://www.rcgroups.com/forums/showpost.php?p=35238879&postcount=21

Tonight I bought 8 HQ Prop 5x4.5 / I need more consistent thrust as the .09 plane is
too big for a 4x4.5 prop, the new props will give me constant speeds around the entire
flying area around 120 mph. Will have to make a plane just for the Fuji .05 at around 8oz
The DART with the Fuji comes in at 13oz. The brief burst of speed past the camera looks
good but fades fast. Will do a video with the 5x4.5 and show the difference. The current
4x4.5 props are surpassing the pipe length its ok to some degree but not optimum.

Out in the field in the heat 91F idle 27,697rpm average vs top end 36,747 rpm difference of
9,050 rpm. But average loaded rpm around the field was 33,000 rpm difference of 5,300 rpm.
Good setup just the wrong prop for the plane.



Also check this out Mini Speed Cobra popular speed plane reduced for a reedie babybee cox engine.
Simple fun flown with a carbon plastic 4.7x4.7E prop. He is over propped but it worked. 4x4.7E would be better.



Last edited by 1/2A Nut on Mon Jul 25, 2016 1:01 am; edited 3 times in total
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Happy Re: DART- TD .09

Post  Cribbs74 on Sun Jul 24, 2016 10:29 pm

Did I read that right? 36K out of a TD .09?

Goodness man, you are going to have to share what you are doing to those engines. Good job!

Edit: I re-read that's a fuji engine. Still impressive though!
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Happy Re: DART- TD .09

Post  getback on Mon Jul 25, 2016 9:22 am

Impressive !! Thanks for the link Brad , the hopmeup people are about 40 miles from me toward the mountains . I will have to wait till my funds are in better shape to advance to another level , gottem saved . Eric Small Cox Logo
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jul 25, 2016 9:43 pm

Thank you glad to share and perhaps inspire some folks to try out tuned pipes Alberto still has
about 4 or 5 left. The first wave of sales ate up the bulk of the batch so now things have slowed
down which gives you a bit of breathing room. Dang Eric talk about the inside track no telling
what they have that never makes it to ebay..

This Site Rocks!



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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Aug 02, 2016 5:07 am

https://www.youtube.com/watch?v=4Ge0MRZroIQ



DART - Fuji .05 / Profi Tuned Pipe HQ 5x4.5N Fast Speed Passes








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Happy Re: DART- TD .09

Post  balogh on Tue Aug 02, 2016 5:25 am

1/2A Nut wrote:Thank you here is a link that will show the process to set up the pipe it's really not hard to do.
By doing the math and bench testing there is very little time spent and really no error just improvements.

http://www.rcgroups.com/forums/showpost.php?p=35238879&postcount=21

Brad,

I got my pipe from Florida yesterday and using a car engine exhaust, I coupled it to a TD051 engine in no time.

I remember you wrote in one of your posts that the small hole on the car engine exhaust manifold, drilled opposite the exhaust extension needs to be plugged, and you have also placed a "half-moon" washer inside the exhaust on the side opposite to the exhaust extension, maybe, to fill up the unwanted space inside the exhaust manifold. My questions:

1. Do these modifications help, or are they indispensable in order to make the pipe (sound vaves, etc...) work efficiently?

2. I assume the time for the sound waves to bounce between the two ends of the pipe, i.e. the resonance frequency at which the engine will rev, is determined by the pipe length primarily, and this should be in the range of 20+k where the TD-s are running, anyways. Dou you think the Reedie engines, typically running below 20k though, would also cooperate with the pipe, without any pipe length extension, or, given the lower rpm range of the reedies, the length of the pipe needs extended in order to lower the resonance frequency of the pipe accordingly?


Thank you.
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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Aug 02, 2016 10:16 am

Yes, I used the groove inside the muffler and filled it with a brass strip. C shape bit more than half moon.

http://www.bolly.com.au/book/Book.php?Chapter=6&Section=3









Published on Apr 25, 2015
Profi Tuned Pipe TD RC .050 non SPI - 1st bench test
Tarno Carb, Cox buggy header pipe with half moon brass shim to block 1 exhaust port
#5 cylinder 2 bypass ports and 2 boost flutes per port -1 shim HC Cox Plug
Tad rich approx 85% to optimum break in mode with new #5 cylinder
- Idle with Tarno carb 12,116 rpm APC 4.5 x 4
- vid recorded 20,996 rpm on the pipe best noted 21,370 rpm 25% nitro
Anticipate 22k +/- static best NV setting - will add one more shim


Last edited by 1/2A Nut on Tue Aug 02, 2016 2:19 pm; edited 1 time in total
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Happy Re: DART- TD .09

Post  balogh on Tue Aug 02, 2016 11:44 am

Brad,

this is my experimental setup, only for taching...the cuff between the car engine exhaust and the tuned pipe is a silicone exhaust extender sold by hobby shops, cut to size.



Initial tach results are not yet reassuring, the engine did not tune up with the pipe. RPM around 20k only. My questions:

1. Is your TD a non-SPI? Mine is SPI and I am afraid that with any exhaust muffling, the SPI is not ideal because of the backflow of gases into the crankcase.

2. Do you recommend increasing the internal diameter of the exhaust extension nozzle on the car muffler to reduce gas pressure drop?

3. I have covered up the small hole opposite the exhaust extension with - preliminarily - some aluminum foil folded in many layers, cut to size, bent to muffler internal diameter. Probably not plugging the small hole gas-tight..is your half-moon gasket  gas-tight to completely close the little hole?

Thank you.
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