Cox Pee Wee .020 ...Which propeller do you use?

I always used Top Flite 5 x 3 nylons. At the time I had no tach, so suspect that power was down from what the smaller props would put out.

But always flew everything that I put those little gems on.

I use the 3-bladed prop because that allows the TD020 to run at a 20+k speed i.e. near its highest output. The 4.5x2 over props it in my experience. .

If regarding Cox props for RC flying I like the 4x2.5 the extra pitch gives the plane some pep.
Traditional paddle type blades still provides great thrust with 4in dia. yet allows good unloaded
rpm. I have had great success with the TD .020 with other props not much testing with the
Pee Wee. Here is the Cox 4x2.5 in action.



TD .020 3ch Lil Speedy
21in span exhaust throttle sleeve, flying with a Cox 4 x 2.5 prop.
1/2 oz tank / With fuel RTF 5.3oz / 25% nitro 18% castor
Static 17,200 rpm / Best pass unloaded 21,640 rpm / 51 mph.

Cribbs74 wrote:Mauricio,

I only use the Cox  3.125x2.5 or the 4.5x2.

These work well enough for CL application. Not sure what would work best for RC. My guess would be the 4.5x2

I am sure other props would work though, I just haven't tried anything else.

Ron

Hi Ron, thanks for commenting on your experience, I'm testing different propellers for the Cox Pee Wee .020 and it turns out that it gives a wide range of uses, I've even seen that they use the Graupner 5x2 propeller running perfectly for RC.
The original manual recommends the tripala or bipala in the measures that you comment, but it turns out that there are many users who have gone further with good results. I have tested 5 x 3 and 5 x 4 inch propellers with very favorable results, always for standard flight and not high speed.
I'm uploading a video with my experience ..... Thanks Ron, a hug!

706jim wrote:I always used Top Flite 5 x 3 nylons. At the time I had no tach, so suspect that power was down from what the smaller props would put out.

But always flew everything that I put those little gems on.

Hello, You are a clear example of uses of propeller measures for a Cox Pee Wee, which is out of what the manual recommends, and I understand and I think it has very good results, I am even sure that you have a very high gear Couple in your engine with a propeller of those measures, thanks for your contribution!

balogh wrote:I use the 3-bladed prop because that allows the TD020 to run at a  20+k speed i.e. near its highest output. The 4.5x2 over props it in my experience. .

How are you ?, It is always very pleasing for me to read your opinions !. I would like to make a reservation and hope that when translating into English, the thing will be well or at least well understood with what I mean:
The .020 Tee Dee engine is very different from the .020 Pee Wee, since it has a rotary valve and the other flap valve.
I have learned how delicate the Cox Pee Wee is .020, I think the flapper valve is very sensitive, just like the needle adjustment, almost micrometric. The flap valve is very sensitive to the flow of combustible air, making the motor never fully firm in its movement, it has variations, typical of the movement of the flap valve; The Tee Dee .020, has another much safer way of running, having no internal variables, almost the engine will keep running even all the time. From there I deduce that the engines are of the same displacement but totally different with regard to their carburetion, since one of them is very variable in the internal movement of the valve flaper, there are many factors, the type of fuel can even cause that The valve "vibrates" differently due to the viscosity of the oil used in a given mixture.
The Cox Pee Wee .020 is more comparable to the Cox Babe Bee .049 or only that the latter is much less sensitive the behavior of the flaper valve making the ride much more even, probably because the size is bigger physically speaking, you understand me?

1/2A Nut wrote:If regarding Cox props for RC flying I like the 4x2.5 the extra pitch gives the plane some pep.
Traditional paddle type blades still provides great thrust with 4in dia. yet allows good unloaded
rpm. I have had great success with the TD .020 with other props not much testing with the
Pee Wee. Here is the Cox 4x2.5 in action.



TD .020 3ch Lil Speedy
21in span exhaust throttle sleeve, flying with a Cox 4 x 2.5 prop.
1/2 oz tank / With fuel RTF  5.3oz / 25% nitro 18% castor
Static 17,200 rpm / Best pass unloaded 21,640 rpm / 51 mph.

Friend Brad !, thank you for always providing such complete information, I think the Tee Dee is very different from Pee Wee, for the reasons I mentioned earlier. Finding the way a Cox Pee Wee in progress is even, requires several points to consider, but there is a considerable variable compared to the Tee Dee, which is that the Pee Wee valve is continuously in motion and that makes it The engine largely during the march has variations of rpm, while the Tee Dee, is much more stable since internally there is nothing that vairie its fuel mixture fuel air ..... it is a beautiful challenge to make a Pee Wee is stable for a long time without changing your gear ...

Here I leave a video of this morning, what do you think ?, how do you see the performance of the engine here?

Mauricio that blue plane is beautiful and flies very well. The Pee Wee is a perfect fit to that plane. I also flew yesterday in perfect sunshine here in Budapest but the temperature was near 0.

Where in Italy do you live with that mild year-end weather?

Happy New Year to all of you.

4.5x2?

1/2A Nut wrote:4.5x2?  

Brad, mine is a 4,5*2 sold by Bernie, the one on the top of the pic below. I rarely use this on TD020-s as I find the 3-bladed to better utilize the engine power allowing speeds the higher 20+k rpm ranges where the TD peaks out.

MauricioB wrote:

balogh wrote:I use the 3-bladed prop because that allows the TD020 to run at a  20+k speed i.e. near its highest output. The 4.5x2 over props it in my experience. .

How are you ?, It is always very pleasing for me to read your opinions !. I would like to make a reservation and hope that when translating into English, the thing will be well or at least well understood with what I mean:
The .020 Tee Dee engine is very different from the .020 Pee Wee, since it has a rotary valve and the other flap valve.
I have learned how delicate the Cox Pee Wee is .020, I think the flapper valve is very sensitive, just like the needle adjustment, almost micrometric. The flap valve is very sensitive to the flow of combustible air, making the motor never fully firm in its movement, it has variations, typical of the movement of the flap valve; The Tee Dee .020, has another much safer way of running, having no internal variables, almost the engine will keep running even all the time. From there I deduce that the engines are of the same displacement but totally different with regard to their carburetion, since one of them is very variable in the internal movement of the valve flaper, there are many factors, the type of fuel can even cause that The valve "vibrates" differently due to the viscosity of the oil used in a given mixture.
The Cox Pee Wee .020 is more comparable to the Cox Babe Bee .049 or only that the latter is much less sensitive the behavior of the flaper valve making the ride much more even, probably because the size is bigger physically speaking, you understand me?

Mauricio,

I agree the TD has a better way of carburation that reed valves. These latter create an obstruction to the air-fuel intake to the crankcase and may not seal perfectly when the crankcase is pressurized. On top is the "float" phenomenon that is said to limit the speed of reedies.

A TD has a fine fuel atomization through the 3 minute holes on the venturi, unobstracted inflow of air-fuel mixture into the cranckase, and perfect seal by the rotary valve when the crankcase is pressurized. Of yourse this is all at the cost of higher fuel consumption but with the benefit of higher output, for the TD.

Apart from the higher output I also prefer the TD-s because of the unlimited fuel taken on-board in a separate tank. I know the small tanks on PeeWees can also be drilled to interconnect the fuel line with an external tank, but I would feel it hard to mutilate a PEE WEE - or any COX engine.

I only have 1 Pee  Wee that I have only bench-run so far, and it is a really spinny lil thing...

I have yet to find the peak power of the TD .020 note in this vid I have loaded the engine down with
a custom cut eflite 3.5x3.5  in the vid it performs well more so it has challenged the torque out
put of the engine. Swept tips would have helped all in all it was a good run best pass 105 mph.
Would be worth trying with a Pee Wee if the plane is clean with a fast wing.

The Pee Wee being a reed valve I think a pressure tank or pressure tap would help with steady fuel
flow and allow more rpm. Mauricio had a good long run with his Pee Wee and it's fuel system.
The 4.5x2 makes for a good free flight prop not much on speed. I would use a eflite 3.75x3 prop to
improve sport performance with the Pee Wee.



Published on Apr 23, 2016

Lil Speedy 3.5x3.5 Prop / 35% Nitro / 20% oil / 84F / 6 to 10 mph winds
Best static 24,644 rpm / 82 mph / Best pass 30,742 rpm /102 mph per prop calc.
Per Doppler Reading E-flite 3.5x3.5 best pass 105.12 mph

E-Flite 3.75x3


This is the only Cox prop I would use with a Pee Wee the 4x2.5



If Bernie would make these back plates for the Pee Wee they would sell like hot cakes
A improved air intake and fine needle valve would yield better performance and we could
all use a 1/2oz fuel tank for nice long runs.  



Mauricio has the yellow helicopter version allowing great run time as shown in his last vid.

I have wondered if Cox developed a special propeller for their Sky Copter helicopters, but guess not as this one has the popular 4.5/2 prop.



Bob

balogh wrote:Mauricio that blue plane is beautiful and flies very well. The Pee Wee is a perfect fit to that plane. I also flew yesterday in perfect sunshine here in Budapest but the temperature was near 0.

Where in Italy do you live with that mild year-end weather?

Happy New Year to all of you.

Andras !, I'm glad you like the flight of the model, I made some adjustments in the engine and the result was very good, in a moment I will place the modifications of the Cox!
I live in Argentina, in these dates here is summer, with temperatures of 30/35 degrees and more!

1/2A Nut wrote:4.5x2?  

No no no .... a little more !!! Here's a closer picture!

[quote="MauricioB
Andras !, I'm glad you like the flight of the model, I made some adjustments in the engine and the result was very good, in a moment I will place the modifications of the Cox!
I live in Argentina, in these dates here is summer, with temperatures of 30/35 degrees and more!    



[/quote]

Hey Mauricio I was under the impression that you were Italian...maybe your name that Italians also use, so now I at least understand why you fly in short sleeve shirt today on the Southern hemisphere while I have a couple of shirts and pullovers on me and shiver when fiddle on the sticks of my Furaba radio flying my planes in frosty Hungary...

What I find amazing is that you have such beautiful throttle control on these little engines throughout the RPM range. You must be using very small servos to control those speeds and control functions.

balogh wrote:[quote="MauricioB
Andras !, I'm glad you like the flight of the model, I made some adjustments in the engine and the result was very good, in a moment I will place the modifications of the Cox!
I live in Argentina, in these dates here is summer, with temperatures of 30/35 degrees and more!    

Hey Mauricio I was under the impression that you were Italian...maybe your name that Italians also use, so now I at least understand why you fly in short sleeve shirt today on the Southern hemisphere  while I have a couple of shirts and pullovers on me and shiver when fiddle on the sticks of my Furaba radio flying my planes in frosty Hungary...[/quote]

Friend, justly, Argentina is a country formed by the native race and the sum of many immigrants who basically came from Europe, largely because of the Second World War.
Argentina is a melting pot of races and customs, here are many Italians, Spaniards, Germans, Jews, etc. My grandparents are Italian.
It is beautiful for me to share through this forum with all of you, because beyond the hobby, I personally like to know customs, ways, other countries and thus learn from other cultures.

rsv1cox wrote:What I find amazing is that you have such beautiful throttle control on these little engines throughout the RPM range.  You must be using very small servos to control those speeds and control functions.

Hello, yes, to control the engine I use a micro servo of 4 grs of weight
The engine control is through the exhaust blocking ring of the engine
I invite you to watch this video:

Well, I commented that I did with my Pee Wee, remove the original tank and place a plate or helicopter plate as comments Brad, the plate originally brings a very small opening of air exhaust fuel, this safe specifically designed for the use of free flight Of the Helicopter. What I did was to modify that hole by adding a bronze insert, with different measures of diameter of exit, so I tried one and another insert until finding the one that best suited my taste.

The propeller I'm using in the video is a Cox Thimble Drone made of 5 x 3 inch soft plastic.
The engine running is very reliable and achieves great traction!

Sure thing Mauricio, Argentina is a melting pot, I had a colleague of mine whose Hungarian parents emigrated to Buenos Aires in 1956 when Hungary revolted against the Soviet Union, the son was already born there and later re-settled in Hungary in the late 1990-s, and BTW was an excellent aviation engineer....though he worked as a cooling tower engineer with me

On the servos that rsv1cox asked above, as far as I am concerned I use the Hytec micro HS 35 HD micro servos for the elevator and aileron control of my Li'l Stick built for my TeeDee010-s, but upgraded recently for  more aggressive flights with TD 020 .

These are tubes of bronze and aluminum with which to manufacture the inserts of different measures of inner diameter. I tried one by one to find the one that allowed me to move the 5 x 3 propeller with good traction.