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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 DART- TD .09

Post  1/2A Nut on Mon Jun 13, 2016 2:27 pm

Smile For TD .09 fans I am working on a project for this engine called the DART

Engine has many custom performance enhancements  Small Cox Logo

- High speed performance crank
- Valentine Turbo Plug Head / OS Turbo Plug
- Kustom Kraftsmans 128 tpi NV
- KK big bore venturi
- Throttle sleeve - cut for SPI
- SPI Cylinder - dual bypass ports (not the RC version)
- Valentine .049 bullet spinner tapped 6-32 thread
- KK .09 back plate with fine hole pressure tap
- Aluminum carb body
- Phenolic thrust washer (for elect. starts)

Will report performance results:
- Master Airscrew 5.5 x 4.5
- Master Airscrew 7x6 modified to 5x6N


Comparison weights as shown: 94g Norvel .074 vs 98.8g modified TD .09











Last edited by 1/2A Nut on Wed Aug 03, 2016 10:08 pm; edited 1 time in total
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jun 13, 2016 2:50 pm

Start of the flying platform 3 channel race plane DART -TD .09










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Happy DART - TD .09

Post  VUgearhead on Mon Jun 13, 2016 3:12 pm

This already looks to be extremely nose heavy from the onset. Good luck with it!
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jun 13, 2016 3:41 pm

CG is panning out just right the RC gear is 50g vs the 98.8g engine nice long tail moment
for stability for speeds 130mph + Wing ended up as: 4" x 2.75" x 32" = 216 Sq. In.
I used two SIG airfoil shaped planks for full symmetrical wing.
1/2" thick will use some thin 64th ply at the saddle to protect the balsa.
Tapper in the front and back may sweep the tips on this one for a change.
RC gear installed in fuselage plenty of room, CG is looking good thus far.
All up weight with aileron servo has it at 10.16 oz / 288g as shown looks
like I will hit around 11.4oz RTF not bad the 5ch Skorch with 1cc pipe and Norvel .061
came out to 11.8oz RTF.
















Last edited by 1/2A Nut on Thu Jun 16, 2016 12:50 am; edited 4 times in total
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Happy Re: DART- TD .09

Post  roddie on Mon Jun 13, 2016 6:15 pm

Looking sharp Brad! I always like your drawings! Your vids are amazing. I don't know how you keep track of these demons in the sky!
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Happy Re: DART- TD .09

Post  NEW222 on Mon Jun 13, 2016 6:50 pm

Wow. Are you sure you are building a plane and not a rocket or missile? Very Happy Me thinks it will be very quick.
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jun 13, 2016 8:11 pm

Thank you Gents, yes the doodles really help to breath life into the conceptual path to wooden nirvana.
The modified TD .09 is really quite special with parts that are so very hard to source it has taken 3yrs ish
to find everything that has been added. The engine will make a good bit of additional rpm over a stock version.
I expect a big boost on the top end. After the trim flight and a few orientation flights to get a handle of its
characteristics I will use the modified Master Airscrew 5x6N (N for narrow cut)
Estimate Static / 20.4k rpm / 11.8oz thrust / 116mph / 171w
Unloaded down wind est. 25.7k +/ up to 146 mph.
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Happy Re: DART- TD .09

Post  pkrankow on Mon Jun 13, 2016 9:03 pm

This is a case where a built up wing would probably end up superior to a solid wing. Choices include:

plowing out a trench and filling it with a CF tube
building up using plank, CF and large triangular/tapered planks available from Sig
building up using more or less traditional ribs and skinning with thin wood

The strength can be maintained with a significant reduction of weight, which should only help performance. Of course in a crash the plank is probably more durable.

Phil
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jun 13, 2016 9:42 pm

The 32in span wing is 2.5oz using two SIG airfoiled panels I had 4 panels to select from so I did a
weight check on all 4 and picked out the two lowest weight ones. Didn't take much glue big plus and
is very stiff twist wise. I am thinking on sweeping the tips with rear scallops at the tips, should bring
it down to around 2.3oz. Airfoil is 1/2in thick at the root. I can use this pic to doodle in the changes
sort out the shape / size of the stab and elevator.




Wallah gives me some insight on the finished look.



Last edited by 1/2A Nut on Tue Jun 14, 2016 12:47 am; edited 1 time in total
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Happy Re: DART- TD .09

Post  NEW222 on Mon Jun 13, 2016 11:02 pm

Coming along nicely.
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Happy Re: DART- TD .09

Post  MauricioB on Tue Jun 14, 2016 12:52 am

Awesome! we produce a cut to heaven! Very Happy ....Mauricio.-
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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Jun 14, 2016 9:36 am

Yesssah thank you.. will for sure have enough power to head in that direction!!

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Happy Re: DART- TD .09

Post  1/2A Nut on Tue Jun 14, 2016 9:51 pm

Need to go to the store and get some more sand paper before going to the next step should I round
off all the surface tips. The wing is a good size with a beefy airfoil ye old sanding bar needs some fresh
stuff before I commence sculpting. I used some of the scrap SIG airfoiled wood for the vertical stab the
wide base makes for a good solid amount of area to glue down and should hold up to some 11+ oz
tumbles if need be. Looking forward to seeing how well it tracks in the wind with such a commanding
airfoil on the vertical stab. The drag is more but may be worth it on gusty days.


11.14oz less 3 nylon horns two aileron push rods and covering.

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Happy Re: DART- TD .09

Post  1/2A Nut on Thu Jun 16, 2016 12:50 am

Ply on the wing now for the saddle and top, aileron servo needs to be inset with some spruce square
stock to screw down the servo will put out up to 28oz of torque at 6v.




CG is shaping up perfect as shown 1.25" behind the leading edge once covered should migrate more
to the sweet spot, having a bit of a swept wing it needs to land around 1.75" off the front edge.





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Happy Re: DART- TD .09

Post  1/2A Nut on Fri Jun 17, 2016 9:52 am

I rounded up the tips dropped the weight to 10.9oz as shown
should be around 11.6oz RTF.










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Happy Re: DART- TD .09

Post  OVERLORD on Fri Jun 17, 2016 10:21 am

Very nice Nut. You make amazing planes!! Small Cox Logo RC Plane Small Cox Logo Thumbs Up Thumbs Up Thumbs Up Thumbs Up Thumbs Up Thumbs Up
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Happy Re: DART- TD .09

Post  1/2A Nut on Fri Jun 17, 2016 2:24 pm

Thank you. this one should be a real treat and keep me flying on windy or low visibility days.
This time of year we get a bit of wind as the hot days start kicking in already had this week
a heat index of 106F !!!! Hot


NANO II vs Dart I

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Happy Re: DART- TD .09

Post  1/2A Nut on Sun Jun 19, 2016 4:07 am









DART -TD .09


11.67oz covered less 3 nylon horns and two short pieces of piano wire
for the ailerons. Custom cut 5x6N prop good for 130mph +
Will go with neon pink for the DART logo and # 9 race number
Full sheet shrink film holds the ailerons and elevator in place, very hard
to see the ailerons lol..the underside thus far is solid neon pink, neon
blue fuselage.












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Happy Re: DART- TD .09

Post  ian1954 on Sun Jun 19, 2016 4:43 am

Now you see it - now you don't!

In the first picture - I see a servo and rubber bands holding the wing on. I've also been meaning to ask how often you change the rubber bands, All the ones I use rot really quickly.

In the second picture - no bands and no servo. No hole for the servo.

Am I looking at the pictures in the wrong order?

I think even I would be able to see that plane whizzing around!
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Happy Re: DART- TD .09

Post  1/2A Nut on Sun Jun 19, 2016 10:20 am

The bands will last some time, I keep mine stored indoors in a air tight bag. I can go a whole season with
a set providing I don't crash or tumble and cause one or two to break.

The first pick is the finished pick the other's preceded the first. Yes this one is far cry from the NANO size
good size plane being a .09. Total weight shown is with the aileron servo mounted this one weighs less than
many .049 planes.

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Happy Re: DART- TD .09

Post  balogh on Sun Jun 19, 2016 11:33 am

1/2A Nut wrote:.....Full sheet shrink film holds the ailerons and elevator in place, very hard
to see the ailerons lol..the underside thus far is solid neon pink, neon
blue fuselage. .........

Brad does that mean you have no dedicated hinges betwen the ailerons and the wings other than the shrink film, and you simply cut it at the end of the ailerons to allow travel? I tried that once but the film on my plane was very stiff when shrunk and the servos could not properly move the flap..
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Happy Re: DART- TD .09

Post  1/2A Nut on Sun Jun 19, 2016 2:23 pm

The top one is how I did it, movement is very easy on the servo using the references shown.
I cover the bottom first with a single full sheet of covering then the same on top.
Very effective gap less and clean looking.

The aileron is 1 folded back when applying the film on the bottom and when doing the top
The aileron is 2 moved in the full down position before applying the heat shrink film.







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Happy Re: DART- TD .09

Post  getback on Mon Jun 20, 2016 8:32 am

Brad that's very impressing in a weeks time you have built a fine looking ship there , Should carry the mail via jet stream. Eyebrows
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Happy Re: DART- TD .09

Post  1/2A Nut on Mon Jun 20, 2016 10:44 pm

Thank you yep yep if all goes well will have a maiden flight vid to share after this weekend!
I have the throttle set up to open only up to 50% to help keep the noise down at the park.
Should still produce more than stock power do to all the mods. I have two RC versions of
the .09 with mufflers and carb. 1 has had over 70 flights on another project back in the
early 90's was very fast and requested by my club to demo at fly in's. This one however
is more leaner and meaner with the mod engine it will be scary fast in the end. Looking
at a modified narrow 4.7x7 prop at 30k / 200 mph down wind passes worth a shot.

RC Plane RC Plane RC Plane Small Cox Logo


Taken from a APC 11x7E prop.

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Happy Re: DART- TD .09

Post  ian1954 on Tue Jun 21, 2016 9:30 am

I find the "electric" props very brittle and it doesn't take much to break one.

I suppose chopping down an eleven inch prop to under five inches leaves it with a substantial root so it will be quite strong.

Are you going to flick start it or use a starter motor?
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Happy Re: DART- TD .09

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