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Cox Engine of The Month
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"Cox Tee Dee .010"



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Lil Speedy II -TD.049 Video 118 MPH Best Pass

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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Sat Feb 20, 2016 1:51 pm

Scored another Ebay special today for $116.50  Small Cox Logo

Engine Product No. 130  new old stock:



Last edited by 1/2A Nut on Tue Feb 23, 2016 9:04 am; edited 1 time in total
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  smooth_bill on Sat Feb 20, 2016 4:05 pm

Nut,

A beautiful engine, and appears to be an older model with the red plastic parts. Good score!

My NIB is dated Mar 1991, and does not have the ports aligned fore and aft. All black plastic parts, with aluminum case and drive washer. Pre Estes engine.

My second one has the same random port alignment, gold case and drive washer, with red carb holder and black tank. Not a mark on the engine, so possibly not run.

Love your detailed history on configurations, and performance figures! I tach all of the engines I run, but never bother writing anything down.

I kept a flight log on every airplane/engine combo when I flew R/C, and really should keep better records now.

When I decided to collect Cox engines, I knew there was no possible way I could afford a complete line of Cox engines. Instead, I decided to collect only pre-Estes half-A and smaller C/L engines, that were made in the early nineties (Red/Black card boxes).

Somehow, other Cox engines have ended up in my collection, including duplicate engines, and displacements up to .090 TD, and Medallion. Now I'm looking for an original .049 Killer Bee to replace the non original that I found with most original parts, and possibly a .15 TD or Medallion.

Meant to ask what R/C systems are you using?

Bill
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Sat Feb 20, 2016 7:46 pm

I would suggest you fly the Red one like TDCribbs has done here in a
CL version. The 130# engine could have been expected by Leroy Cox
himself. Small Cox Logo





Could fly right in the back yard the noise wouldn't be bad or local patch
of open field. This one could be launched on a table in a outboard wing sleeve.
Or round the pole with a elevator servo, Rx, and battery and landing gear.

I used an Orange 4 channel 2.8g RX and three 3.7g servos:

http://www.ebay.com/itm/RC-Universal-ESC-Control-Switch-PNP-Plug-N-Play-Design-MPI-/381537521805?

http://www.ebay.com/itm/131333183964?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.com/itm/Dynamite-DYNB0003-NiMH-Battery-Pack-4-8v-150mAh-for-Losi-LOSB0868-1-36-Micro-/291678087148?hash=item43e95e67ec:g:6XkAAOSwgQ9V1WyE

http://www.ebay.com/itm/131300880759?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Mon Feb 22, 2016 1:51 am

Saturday I decided it was time to reset the ball socket for the first time with this engine.
I had 6 to 8 runs on the bench and about 20 flights it was time to check.

I soaked the piston in after run oil prior to resetting the socket, it takes very light taps on the reset
tool to motivate the socket the oil inside the socket will help on the first flight to reduce break in wear.

The result was a new best pass of 36,418 rpm
I noticed some low end vibrations with the black flexible prop
with all best efforts to insure best alignment it was still present.
The vibration will wear out the socket faster and adds heat to
the engine when I am flying in low throttle mode.

I took the more stable pitched grey prop and filed flat sharp
square tips making the prop 2.9x1.25 to reduce prop tip vortices.
To further reduce vibrations I used a short bolt and washer to keep
the spinning mass up close to the prop. The results gave me 28,140 rpm static.
very smooth at idle. Will flight test this to see if it unloads better next.



Pic from today's flights no sunny day but the wind was down to 6-11 mph.


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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  balogh on Mon Feb 22, 2016 3:16 am

Thanks, Brad, for the review, very interesting.

I have some of my TD010-s (and had 1 that was lost in the field due to a RX battery running short of juice mid-air) with many hours of runtime on them, but I never had to reset the balljoint...I also do not use 35% nitro fuel, though.

When I tap the balljoint in my COX engines, I do it after I have cleaned the oil from the joint with break cleaner spray or similar, to make sure I feel the real "play" of the dry surfaces before I complete the resetting. When I add some lube oil afterwards the remaining gap almost disappears thanksto the oil film added to the surface. I am not sure which way is better, I do it after I mushroomed a few pistons at the beginning of my "garage tuning" carrier.

In your previous post you shared this lin on a control switch that I like very much, and was trying to find one from the same maker, with a charge cable also included.
http://www.ebay.com/itm/RC-Universal-ESC-Control-Switch-PNP-Plug-N-Play-Design-MPI-/381537521805?


Do you have any link to a similar micro switch on ebay with a charge cable also included?

Thanks, András.
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Mon Feb 22, 2016 4:09 am

Hi András,
That micro switch is the smallest I can find with the correct connectors, you have to add
the second charge port either on the battery or the battery side of the switch and insure
you never have the RX powered up while charging of course.

I have another prop mode I want to try to eek out some more top end speed. I have plenty
of the cox grey props to mess with so decided I will do a back cut next and see if I can bust
38k rpm / 45 mph or 72.4 Kmh. It should take some of the load off the ball socket and rod.
Of course the throttle sleeve could be removed for more power but I am too spoiled using it now.




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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  balogh on Mon Feb 22, 2016 5:23 am

Brad,

I like your experiments with prop mods, but I would try to fashion a prop to hit the duty point at the engine speed near the max output i.e. around 32k, because I believe if you move the engine-prop duty point to above 33k then, even if you have a high rpm like 38k, the actual engine power translated by the prop to thrust will be less than at the max engine output rpm.

The engine output curves of the links below refer. Though different sources, both put the max output to somewhere around 32k..meaning, the "unloaded" speed of the engine in air should max out at this rpm, any other rpm will lower the engine output/prop thrust

http://www.sceptreflight.com/Model%20Engine%20Tests/Cox%20Tee%20Dee%20010%20(1).html
http://www.mh-aerotools.de/airfoils/cox_frameset.htm
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Mon Feb 22, 2016 9:08 am

The author who tested the .010 R.H.Warring most likely used 25% nitro.
He noted 32k being the best power and best torque at 24k / 1oz

I am having fun with the sound of RPM and subsequent speed it provides.
Using 35% nitro I would imagine the power band moves up past 32K.


The 3x2E green drone prop does a bit better staying closer to the 25% nitro power band.

Best pass cross wind 32,792 rpm / 62 mph
Solid pull better loops and faster turns great prop!

Best down wind pass:
33,941rpm / 64 mph - Looks like about 55 mph.
The best prop per power band for speed would be a 3x2.5 if at 32k unloaded.




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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Tue Feb 23, 2016 12:21 am

Modified / polished the prop and added a second head shim will test this one
next. It looks more scale to the engine than the stock paddle props.



Vid from Sunday after resetting the ball socket, finally a day where the wind wasn't as bad.
I was able to horse it around and do more acro.



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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Tue Feb 23, 2016 8:47 pm

UPDATE the prop was bench tested and gives 27,858 rpm / 35% nitro with 2 shims
I dare not run it on 1 shim. With the tips squared off and no back cut with 1 shim
it read 28,100 rpm. I am almost back up there without the added compression this
means less prop load on the engine and ball socket.
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Sun Feb 28, 2016 4:43 pm

Welp after Saturdays flying in the gusty winds I have retired the TD .01 from the Lil Speedy II.
All together 4,5,5,5 and 4 for 23 flights. I will save the TD .010 for the next more refined build.
I knew after building the plane the potential would be there to do a power upgrade.
The TD .010 really did well with the plane and deserves taking the engine to the next
level. It flew the Lil Speedy good in the wind a thinner fuselage is in order to max out
the engines abilities. I will go with all gear in a straight line and use just two servos and
a smaller 1/2oz tank to reduce all up weight RTF 3.5oz. Engine will be in a cowl with a thin
walled aluminum header pipe for exhaust. Goo control and engine tone will be neat. 40 Sq. In. wing.

New Design Called:  TD .010-NANO
Custom 2.5x3E Prop.
Est.
Static 28k / 80 mph
Down wind 36.5k / 104mph
Cross wind 34.4k / 98mph




TD .020 Static test per prop calc:
3.75x3 / 22,790 rpm / 65 mph / 5.3oz thrust / 37w
Est. if at 26,270 rpm unloaded for 75 mph / more if down from a dive wind.
Plane with engine 142.4g / 5oz dry weight.
With fuel at full throttle it pulled out of my hand straight up.
The engine prop combo is actually making over 5.3oz of thrust.
If I don't want that much thrust can do static 3x4/ 23k rpm / 87 mph.  


The TD .020 fit perfect linkage and all was already planed prior to mounted the TD .010.
Will post a vid next time out at the field.

Here is a trick to adjust the engines bypass ports to line them up with the spinning flywheel
You can use .020 head shims, this will boost rpm. A ex Cox engine tech mentioned aligning for
rpm but didn't say how to do it for the smaller engines as shims are only made for the .049's
I haven't check yet but the .049 head shim may work with the TD .020 cylinder to line up too.
They may have filed down the top of the crank case a bit prior to anodizing to insure they
lined up back in the day for the smaller engines. I adjusted the TD .010 cylinder and filed
down the bottom of the glow plug to keep compression the same 1 shim for the glow plug.
The tested engine went from 26,410k to 27,790k and took two shims at the cylinder. Still
had a hair of SPI hard to see with the .010 I use magnifying glass to check.




Another item of note the Dynamite 150 cells took 182 mah peaked with the smart charger this is
after the battery was used at home from flying 5 flights I was setting up the servo for the TD .020
and ran the battery down to the point the RX stopped. Also comparison shot to the new 80mah battery
that I will be using with the TD .010-NANO 4 cell pack 10.8g / 20mm x 10mm in size. With the smart
charger should hold about 100mah.



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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Sat Mar 05, 2016 9:37 pm



Published on Mar 5, 2016
TD .020 / 3.75 x 3E Prop / Best Level Pass- 29,554 RPM / 84 MPH / Throttle Sleeve
Static at launch 22,529 / 4.5oz thrust / 64mph / 36w / per prop calc
Best dive down wind out of 3 video's / 31,419 rpm / 89.3 mph
RTF 5.3oz - Actually has unlimited vertical / 35% Nitro / Run time 8.06 mins


Last edited by 1/2A Nut on Sun Mar 06, 2016 5:32 am; edited 1 time in total
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  Mark Boesen on Sat Mar 05, 2016 9:56 pm

Nicely done, brings back memories of my 1/2a R/C Pylon days....little planes get little really fast, when they're fast!
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Sun Mar 06, 2016 5:45 am

Yes this little one is visually good for about 70 yards away tops at full throttle.
If ran slower it can be seen a bit further away.

Note the 3.75x3 prop used is a E-flite F-27Q Stryker prop
So far it has held up to 3 flights and two bench test sessions.
The surface is shinny if direct high nitro hits it the sheen goes
away so far no other effect.
Recommend oiling the blade before use to protect from raw
fuel for the first time. Could clear coat if applied even.

In the mail Carbon 4 x 2.8 drone props to test. 6g. ea.
Based on the 3.75x3 prop results the thicker airfoil should unload
around 28.5k / 76mph stiffer blade more dia. for faster turns.


Last edited by 1/2A Nut on Sun Mar 06, 2016 1:54 pm; edited 1 time in total
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  getback on Sun Mar 06, 2016 12:32 pm

DAMMIT! MAN !! Devil that was kick butt , I am afraid one of these days your going to bee wearing that thing as close as you get to your self No! Enjoyed ! Thanks do you know what those E-props are rated at ? Eric Paranoid
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An impressed forum member

Post  706jim on Sun Mar 06, 2016 3:52 pm

When those little engines came out in 1961, there were modellers that prophesized that the 0.010 could be used for indoor flight. Even Leroy Cox couldn't have imagined what you have done with these little jewels!

While fast planes are not really my cup of tea, I still enjoy what you are doing here and look forward to future videos.

They are just a welcome relief from electrics and quad copter drones that seem to be everywhere these days.
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Mon Mar 07, 2016 8:12 am

There is an old vintage photo of someone doing a CL display with a TD .010 for some kids at a school indoors.




Published on Mar 5, 2016

TD .020 / 3.75 x 3E Prop / Best Level Pass- 29,554 RPM / 84 MPH / Throttle Sleeve
Static at launch 22,529 / 4.5oz thrust / 64mph / 36w / per prop calc
Best dive down wind out of 3 video's / 31,419 rpm / 89.3 mph
RTF 5.3oz - Actually has unlimited vertical / 35% Nitro / Run time 8.06 mins

New design called the NANO .010 in the works







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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Tue Mar 08, 2016 4:14 am

2.3oz less tail feathers / push rods and horns.
2ch. with all the gear as previously shown.
Est. RTF with fuel 2.8oz. / 45 Sq. In wing less cut out ailerons.
Almost Fully Symmetrical wing with washout in the tips.
Used a SIG airfoil solid balsa wing panel.
2.5x3E  prop if at 32k rpm / 91 mph.



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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Wed Mar 09, 2016 6:01 am

76g  less horns / rods and covering. 1.62oz less than the Lil Speedy with the .010 engine.









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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Sat Mar 12, 2016 2:47 am

83.8g as shown all gear including the elevator push rod.





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Edit:
You can buy the following and use a long bar sander to make a matching top / bottom
airfoil. Another trick is to add templates on the tips to help guide the shape can cut the
wing in half and add a center ply template and sand both wing panels down to it.



Last edited by 1/2A Nut on Sat Mar 12, 2016 6:29 am; edited 1 time in total
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  balogh on Sat Mar 12, 2016 4:00 am

Brad

I am equally amazed and inspired...I would follow you like I did with the Skorch 049 but I am afraid I won't be able to sand a symmetrical pair of wings with my limited hand-skills and tooling.

Any smart idea on how to make sure you do not over-sand either side /half of the wing? Ho do you calibrate the airfoil to remain constant along the full span? Etc...Etc...


Good luck András.
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Sat Mar 12, 2016 10:44 am

Done RTF will post a vid and test flight with a tame stock prop first. Small Cox Logo







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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  fit90 on Sat Mar 12, 2016 10:55 am

It looks great! If your hand wasn't there for reference I would have thought it was a much larger plane.
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  1/2A Nut on Tue Mar 15, 2016 8:51 am

Lol yes it is the smallest IC Engine powered RC plane I have made to date.

You need full screen monitor and 720 to 1080P HD to view this micro test flight.

https://www.youtube.com/watch?v=XmRPcHR1AOc



RPM unloaded easy with this small one best pass 36,337 rpm.Small Cox Logo

Tracks very well with a fully symmetrical airfoil equal fast moving air pressure means more effective ailierons.

Took it out for a test flight I knew it would be fast even on the black stock prop so I had
the control surfaces set to just 40% throw on the ailerons and 35% on the elevator.
The elevator seemed ok but the roll rate proved to be wayyy too much as you will see in
this maiden flight. It rolls in at full throttle after some flying around I was going for a fast
left turn and instead I was completely caught off guard as I hadn't tested max throws yet
so the plane rolled in and smacked into the muddy ground inverted. The venturi got a snouts full
of wet dirt and the exhaust intakes compromised with wet dirt. So I took it home for a proper
cleaning to avoid compression loss. No damage to the plane using thin ply for the fuselage makes
this a very strong plane and the engine is ready to go. I have a 1:1 thrust ratio and catch that
on vid next time. I now have the throws dialed under 20% and will vid more flights this weekend
flying closer to the cam and pick out the best video to post here. Till then here is a taste of the
fastest 2 Ch TD .010  RC plane on the planet, recorded and posted on the world wide web.
Once dialed in swan dives from down wind will exceed 37,000 rpm with a stock prop.  
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

Post  balogh on Tue Mar 15, 2016 12:29 pm

Brad,

despite the unplanned landing it was an amazing, and astonishingly fast maiden flight. Glad to hear the bird and the engine survived. I will go and try to build something similar for my 020-s. My old Roaring 20 I fly with 020-s is just way too soaked with castor and a bit heavy.

Your planes are a real inspiration for me. Thanks
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Re: Lil Speedy II -TD.049 Video 118 MPH Best Pass

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