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

Thank you Mauricio yes modifying props takes a bit of practice.

Kris on the elevator servo I always use the closes hole to the servos spline.
All surface horns are sized proportional to the plane and for minimal drag.
The aileron servo horn keeps minimal piano wire angle to the surface horns.
The modern servo centering ability is very good per specs and after flying I
have found it to do a good job of keeping trim. I have been flying for over 30 yrs
with countless successful design / build projects and fully understand my choices.

Congradulations on getting a new home and space for modeling projects.
I do hope so see you flying a new 1/2A project just 45 mins. a day could
have you something flying. A sheet wing racer or profile plane is fast to build.
Slow fly planes can fly in small spaces as an option too.

Hey there from New Zealand, I thought I’d jump in here and thank you for the inspiration to build one of these, as soon as I saw the nano II I just had to have one, I only have a pee wee on it right now running with the cox speed prop 4.5x4 I believe and 20% nitro my best speed by the radar gun got me 48.5mph not bad for a pee wee I thought, last night I ran a gemfan 3x5.6 tri blade for my fpv micro quad on the bench and it seriously screams compared to the other prop, I didn’t have a tach with me but by ear it’s going to be fast! I had trouble running the eflite 4x4.75 for the umx striker because there wasn’t enough mass to keep it going so I was surprised the 3” prop started as well as it did [url=https://servimg.com/view/15468641/3570][img]

Can you try posting the image again?

Should be a Cox 4x2.5 speed prop for the Pee Wee.
Alternatively there are many other potential props to use.
The Striker 3.75x3 requires a spring starter to use.
A quality drone prop with speed tips 4x3 should work well too.


Here is a vid with the Striker Prop 3P makes for good speed with the .020



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 / 4.6oz 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 9.06 mins




Published on Feb 4, 2018

NANO III Cox Tee Dee .050 RC / 2nd test flight
Best pass down wind 27,780 rpm / 132 mph prop speed
TD RC .051 with stock muffler with a pressure tap.

Sorry, New to the forums when I figure out how to post the pic I’ll do it
I was using the green 4.5x4 speed prop on the pee wee even though it’s for an .049 it was the fastest prop I tried that day
I’ll try the spring starter on the 3.75x3 or build myself a electric starter, I’m sick of being whacked on the back of the finger from the light props

Congradulations you have done a fine job recreating the design well done!!
If you can get some vid of it flying please share.
Note the servo is in the CG zone this makes the wing a bit weak in the
crucial load area. See pic for future builds. I also sheet the center section
with 1/64th ply for the .049 size. How much does this one weigh?

I didn’t even think about the servo on the cg, I just tried to keep the linkages as Long as possible to help with the geometry
This one does have 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

Can you get some vid of it flying and post on Youtube so you can link it to this thread??

Sure can it will be tomorrow before I can fly it again, I’ll also try out the gemfan 3052 on the bench tonight and see what I can get static rpm wise

The lower rpm of the Pee Wee gets it's own considerations for best performance prop.
Check out the DALPROP Cyclone 3x5.6  the pitch is a bit more than the Gemfan Prop 3x5.2
Let us know how the Gemfan does I expect it will work well.


Gemfan 3x5.2


I have yet to test these but the pitch is outstanding for the .020





Jordan flying his Pee Wee powered NANO II



Jordan Kearney
Published on Feb 8, 2018
SUBSCRIBED 1  

Rich flight of my Cox pee wee with a cox 4.5x4 speed prop for an .049
5.5cc internal tank 20% nitro /20% castor


Jordan I shared your vid here on RC Groups

https://www.rcgroups.com/forums/showthread.php?199489-Post-your-1-2A-pics-2/page110#post39140781

APC Carbon 5.25x6.25 props came in the mail today    
Cut one down to 4x6.25 / 2.6g if it unloads to:
27K / 160
26k / 154
25k / 148

Are these sold by APC on their website??

That looks like a fast prop! I’d like to see the results,
Speaking of props, tonight I ran my pee wee with the gemfan 3052 and at full throttle I noticed the prop started to vibrate and wobble so I took a step back, maybe it was a little out of balance?
I also had a racecraft 3x76 in my stash
although I do remember you saying something about the massive scoop it some electric props actually restricting the rpm and not actually do much in the air this screamed on the bench more than the gemfan.

I had trouble with my methods of measuring rpm.
First I tried an app I brought today which when I tested at work in the tractor  it matched perfectly to the digital readout on the dash however I got very weird readings from the pee wee, often jumping between 1880-45300rpm
So I scraped that idea and borrowed a cheap tach of a club member but by this time it was dark out and I couldn’t find any sources of natural light

What do you guys use to to get a good reading?
Also I see in some of the videos you can get good speed and rpm readings in the air
What do you use to do that?  

Hi Littlebuzz,

apart from conventional tach meters sold by Hobbyco and others on ebay,:


you may want to try a free Android app "RPM Gauge" if you use Samsung or similar smartphone:



this is audio-taching the engine, and accurate enough in open air use (the readings above are not for the same engine)...in my garage the echo often makes it unreliable..

1/2A Nut wrote:APC Carbon 5.25x6.25 props came in the mail today    
Cut one down to 4x6.25 / 2.6g if it unloads to:
27K / 160
26k / 154
25k / 148

Brad, the reform of the propeller do you do it by means of sandpaper? Do you use any comparative template?

I use the audio Doppler app and check my vids that way making sure I set the presets to
be close to actual rpm expected. I have a laser tach, and photo cell tachs.

Jordan the prop wobble in static mode can be expected as it is under the most stress at
that stage best just fly it and see if there is any improvements in speed. Correct I do
not like high pitch blades at the hub like the APC would prefer constant pitch props for
IC engine use. The aggressive pitch takes a lot out of the engines torque. We have to
simply fly and see the results in the end to confirm any bench testing results. I have a
radar gun but rarely have anyone with me to do the readings while I fly so the doppler
app is used 100% of the time at a minimal then I use a thrust / speed calculator online
and also wav scope software to derive the speeds.

http://www.godolloairport.hu/calc/strc_eng/index.htm

http://www.rcpro.org/rccalc/PitchSpeed.aspx

I use scissors, and a sanding bar made out of aluminum to form the prop shape then
check with a prop balancer. It is more important to make sure the blade size is the same
first as in the air it will have the most dynamic / physical influence. You can add a bit of
CA to the blade to add a weight to the the blade with the least weight as a trick to balance
I fine sand the CA if added to blend well and not influence the airfoil anymore than needed
to balance.

APC 5.25x6.25EC Electric Carbon Propeller 5.25 x 6.25EC LP053625EC NEW In Stock

You can't beat an analogue tach. The needle smooths out those rpm variations that the digital tachs generate. As for the Pee Wee engine, I could never get more than about 2 minutes from the internal tank. Mind you that proved to be enough running time to send a free flight model out of sight many years ago.

Nice Flight Jordan , at least i could see most the plane as with Brad the Nano's go so fast lone time i can really see them is when Zooming by his head !! Brad looks like you have found a new friend to play with . I need to get a prop balancer what brand is the one you 're using ? 30 yrs. that's a lot of fly time my friend !! That is a good job of coping your design fro only some pictures !!

1/2A Nut wrote:..........I use a thrust / speed calculator online
and also wav scope software to derive the speeds.  

http://www.godolloairport.hu/calc/strc_eng/index.htm

...................

I am proud to recognize this is a Hungarian calculator...."godolloairport" means airport at the city of Gödöllő, 30 miles NE of Budapest, the capital of Hungary

Yes it's a good program to use highly recommend for it's flexibility lucky to have it.

Jordan what is the wing span of the .020 Nano, do you have any build photos?

Will test the carbon 6.25P prop next and update data on the photo.





If the 6.25P hits 27k prop speed will be 160 mph will be flying Saturday and post a vid.

Bought 2 APC props yesterday, a 4.75x4.75 and a 4.7x4.25 but the TD049 could not swing them faster than 17k...


Using the calculator this means a shaft power around 85W that is the ballpark peak performance figure for this engine. Have 20% nitro in the fuel...what do I do wrong not being able to achieve the higher rpm-s measured by you with similar props Brad? I know the muffler may rob 1.....1,5k max but I would still be way below 20k without it..

No not really that similar your props are bigger in dia. and blade width.
The gray props weigh more when left in stock form.

See pic I cut them down as shown.

Plus I use a:
- Galbreath Head adapter  
- Nelson turbo plug
- High performance crank  
- Pressure tap on the muffler
- Muffler shape that allows the engine to breath
- Fuel tubing in the center of the prop for alignment / minimum vibrations lets the engine sing!
- Also I use higher nitro then you do 25% and 35%

- Lastly I oil the crank shaft with after run oil after flying.
 I run up the engine with my starter to spread the oil around
 then I stand up the planes engine on its nose over night to let the
oil run out of prop thrust plate when that happens I flip the engine over to
 insure the entire crank shaft has a coat of oil. The engine is never dry.
 By doing so the next time I fly the engine is well protected / lubricated.
 Less wear more rpm.    

You see the conditions are far from the same but by modifying the prop
you can get more rpm. I suggest you fly with the 4.75x4.25 first as is.
It will unload around 25.6k / 103 mph. Not bad for a stock engine.
Real speed should be about 90 mph do to plane size and weight which
is much more than mine this causes the engine to load up more work
harder turn less rpm. You will need the thrust the stock 4.75x4.25 makes
as your planes weight and size is going to require thrust while you learn
to fly it and tune the engine for top rpm.

You have a dry weight of 350g as I recall with battery. 12.4oz  
The NANO has a dry weight of 256g or 9.03oz.
My TD will unload more in the air with more prop load than you can use due to
the all conditions I have described.  Note your airfoil is thicker than
mine too this will load the TD more of course. I would say you are 35% in
the hole in comparison at this time with all factors summed up.

When ready:
Ultimately your APC props cut to 4.4x4.75N / 4.6x4.25N will yield good
speed a bit over 175 kph. down wind with 25% nitro. First we need to
evaluate what is possible with the stock prop before making decisions.
The flexible black 4.5x4 cox prop will be worth sacrificing bad landings with
too it can put up with some abuse. Make sure you have the prop set windmill
horizontal with the ground when the engine has stopped running to help protect
the props.  

Thanks Brad. As to engine setup I have the drop in glow insert. I never had success with glow plugs in COX engines though, but lost thousands of rpm-s no matter the number of shims under the head. Will try the Galbreath adapter and turbo plug if I find them for sale.  Do you happen to know who makes and sells them? Of course I also use fuel tubing to center the oversized prop hole on the screw. Vibrations are almost nil.

I will return to the COX 5x4 and 4.5x4 props set in horizontal dead stick position as you suggest... they always met at least my recreational flight expectations.

The one thing I still need to fly is Spring   ...