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

MauricioB Sat Dec 31, 2016 9:08 am

balogh wrote: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

This is life, history ... now many are leaving Argentina in search of new horizons, I have my brother and his family many years ago living in Spain, Barcelona, specifically in the company SEAT.
Unfortunately it hurts to say it, but the bad policies, the bad leadership and even the lack of education, have been hurting this society. God knows I pray for this to change in my country!

MauricioB Sat Dec 31, 2016 9:12 am

1/2A Nut Sat Dec 31, 2016 10:11 am

5x3?

MauricioB Sat Dec 31, 2016 10:14 am

1/2A Nut wrote:5x3?

Yes! Dear friend! Beers

Cox Pee Wee .020 ...Which propeller do you use? - Page 2 Foto1253

MauricioB Sat Dec 31, 2016 10:32 am

Maybe this way you can see better ...

Cox Pee Wee .020 ...Which propeller do you use? - Page 2 Foto1254

roddie Sat Dec 31, 2016 10:37 am

MauricioB wrote:

Hi Mauricio! Happy New Year! Your RC flying-skills are excellent! Do you do any crop-dusting?? Laughing

Although I don't have experience with the .020 engine.. I was thinking about the Cox 5" x 2" 2-blade black prop also.

Here's one I have. These props came with my Cox Cosmic Wind C/L airplane (.049 reed-valve powered)

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Cox Pee Wee .020 ...Which propeller do you use? - Page 2 Cox_co12

I agree with Brad about the production of a smaller "horseshoe" (product-style) backplate for the Pee Wee being very useful.

I like your re-engineering of the helicopter backplate! Thumbs Up

I think it's the only other "back-end" that Cox made for the reed-valve variant. Some of the Cox tether-cars had .020 engines.. but I'm pretty sure that they all had integral fuel tanks. (Pee Wees)

Kim Sat Dec 31, 2016 3:44 pm

Great thread Mauricio!

Hope you all have a great New Year !

Kim

1/2A Nut Sat Dec 31, 2016 6:39 pm

The 4x2.5 will make the Pee Wee come alive the higher rpm will improve
fuel draw naturally with the back plate.

If you own a Pee Wee you will for sure buy at least 1 back plate to try.
I would imagine 2000+ sales just in the first year, perhaps more as
there are at least 12k Pee Wee engines still able to function around the world.
They collect dust due to low run time.

MauricioB Sun Jan 01, 2017 12:29 am

roddie wrote:

Hi Mauricio! Happy New Year! Your RC flying-skills are excellent! Do you do any crop-dusting?? Although I don't have experience with the .020 engine.. I was thinking about the Cox 5" x 2" 2-blade black prop also.

Here's one I have. These props came with my Cox Cosmic Wind C/L airplane (.049 reed-valve powered)

I agree with Brad about the production of a smaller "horseshoe" (product-style) backplate for the Pee Wee being very useful.

I like your re-engineering of the helicopter backplate! I think it's the only other "back-end" that Cox made for the reed-valve variant. Some of the Cox tether-cars had .020 engines.. but I'm pretty sure that they all had integral fuel tanks. (Pee Wees)

Roddie good to read you !!, thanks for your words, I'm so glad you like the flights! I want to wish you and your family a very good 2017, that the problems are solved and that the joys come much more often!
I have seen your propellers, very interesting to test results ... everything in this is experience to test error. Thank you for always sharing your experiences!

MauricioB Sun Jan 01, 2017 12:31 am

Kim wrote:Great thread Mauricio!

Hope you all have a great New Year !

Kim

Thank you Kim! I wish you a very good year too!!

MauricioB Sun Jan 01, 2017 1:07 am

And do not be jealous Cox Tee Dee 010, I also did a video to dismiss the year !, I hope you like it. Small Cox Logo

1/2A Nut Sun Jan 01, 2017 3:39 pm

Does anyone know what the orange prop size is?????
Is that a standard .049 needle valve looks big.

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rsv1cox Sun Jan 01, 2017 3:43 pm

1/2A Nut wrote:Does anyone know what the orange prop size is?????
Is that a standard .049 needle valve????

4.5/2 Not sure about the NVA.

1/2A Nut Sun Jan 01, 2017 3:48 pm

Thank you I always wondered if they did some special prop testing for
vertical take off. The prop shape would be very good scaled down to
4D x 2.75P

Think I solved the NV question looks like this one for a .049

Cox Pee Wee .020 ...Which propeller do you use? - Page 2 S-l16013

Note the plastic venturi is much larger than the Pee Wee standard tank stem hole ID is much smaller to the reed valve.
Having said that potential power boost with more air / fuel for the copter where fuel economy is not a issue more so
enough power to lift all that plastic.

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A horse shoe all aluminum back plate would be great for cooling and strength to the firewall.

Note a copter back plate just sold for premium price of $27.50 Shocked

http://www.ebay.com/itm/391646533575?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

MauricioB Mon Jan 02, 2017 12:13 am

Brad, I'm not sure I understand, but I'll leave a response in case it's useful:
The needle of the yellow plate of the Cox 020, is equal in diameter and thread to that of any needle of a rear plate of a Cox 049.

MauricioB Mon Jan 02, 2017 7:21 am

Roddie, here I tried a 5x4 propeller:

1/2A Nut Sat Jan 07, 2017 9:39 pm

Stock tank is 7.6g less it's needle valve / spring and 4 bolts.

New engine is a mere 22.8g with prop spinner ready to run.
The intake hole is good the hole at the reed valve is reduced
so I did what Mauricio did and drilled out the hole. Now
unlimited run time with less overall weight. I tried a long stem
.049 needle valve it fits no bench tests yet. Will post a performance
prop test with the Cox 4x2.5 and E-flite 3.75x3
We need Bernie to make some horse shoe style back plates to convert
Pee Wee engines for RC use. I will use a 1/2oz tank good for a nice
10min run. FYI sent Bernie a message. Small Cox Logo

Mauricio can you take a pic of the stock needle valve so I can compare?
Update I have fired up the engine it runs at 2.25 turns out with the current needle valve.

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MauricioB Sun Jan 08, 2017 11:13 am

1/2A Nut wrote:Stock tank is 7.6g less it's needle valve / spring and 4 bolts.

New engine is a mere 22.8g with prop spinner ready to run.
The intake hole is good the hole at the reed valve is reduced
so I did what Mauricio did and drilled out the hole. Now
unlimited run time with less overall weight. I tried a long stem
.049 needle valve it fits no bench tests yet. Will post a performance
prop test with the Cox 4x2.5 and E-flite 3.75x3
We need Bernie to make some horse shoe style back plates to convert
Pee Wee engines for RC use. I will use a 1/2oz tank good for a nice
10min run. FYI sent Bernie a message.

Mauricio can you take a pic of the stock needle valve so I can compare?
Update I have fired up the engine it runs at 2.25 turns out with the current needle valve.

Hello! Good thing you got the helicopter cap, I'm going to see if I dismantled my Pee Wee so I put a picture so you can see how to insert the insert, which is just put in the pressure hole! Smile

1/2A Nut Sun Jan 08, 2017 2:02 pm

Here is the shape tip of the Needle Valve that seems to fit the engine. I ask because my engine
back plate did not come with a needle valve.

Small Cox Logo

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I am using my steel strap designed throttle sleeve, allows you to fit over the cylinder flange. Very simple to make but small
and requires a bit of time and care for a good fit. I used thick paper for a template.

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MauricioB Sun Jan 08, 2017 2:36 pm

Hi Brad, just thought to make something like this in brass or steel, how about your results ??

MauricioB Sun Jan 08, 2017 2:52 pm

1/2A Nut wrote:Here is the shape tip of the Needle Valve that seems to fit the engine. I ask because my engine
back plate did not come with a needle valve.

I am using my steel strap designed throttle sleeve, allows you to fit over the cylinder flange. Very simple to make but small
and requires a bit of time and care for a good fit. I used thick paper for a template.

IMPORTANT: Secure the rear tie plate with washers to get the engine to get enough air through the venturi tube!

MauricioB Sun Jan 08, 2017 2:57 pm

Here I show you how to modify the air intake of the tube or conduit, and where you can even see the bronze insert (brass tube), it is placed under pressure and can be removed by taking it with a screw and pulling it as if it were uncovering a Came with corks, so you can try different measures to achieve what is useful!
It is also important to place a silicone tube on the needle, to prevent the engine from drawing air through there as you can see in the first photo!

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1/2A Nut Sun Jan 08, 2017 3:00 pm

Thank you

can you take a picture of the needle valve? I need to confirm which shape I need to use.

Engine results thus far:
3.75 x 3

Static: 18,497 rpm / 53mph / 20.14w /.027 hp / 3.2oz thrust.

With a stock prop the thrust will go up but the 2P will drop speed
dramatically. I would design a 4oz plane for this engine RTF with
the 3P prop performance would be outstanding. Est. 23k + unloaded
for 65 to 70mph down wind passes. Great sport engine for it's weight
making good use of the Pee Wee parts.

To compare the Pee Wee .020 parts to the TD .020

Per Vid Published on Apr 3, 2016:
TD .020
Unloaded 3.75x3 / 31,257 rpm / 148.37 km h / 92.19 mph
Static at launch 23k / 4.5oz thrust / 64mph / 36w / per prop calc

Note for the test the air intake had good breathing.

Cox Pee Wee .020 ...Which propeller do you use? - Page 2 Imag4310

Note prop weight is everything for performance.
E-flite 3.75x3
At 2.9g I show a stock .020 spinner
At 2.3g I use a bored out .010 spinner
At 2.5g I use a Valentine .010 spinner then tap it for a .020 prop bolt.
Note that prop has back cut for better top end speed instant speed tipped prop.

Cox Pee Wee .020 ...Which propeller do you use? - Page 2 Imag4311

MauricioB Sun Jan 08, 2017 3:33 pm

Yes Sr!

MauricioB Sun Jan 08, 2017 3:47 pm

Regarding the ventilation (air intake) test the distance of the plate from the wood about 3 to 4 millimeters with washers, it is very possible that you notice a rise of RPM, to my step, surely there is generated a turbulence and precisely you can work on it too! Eyebrows

Here the friend photos, the aluminum is the original plate, is exactly the same as the bronze, works the same with one or the other, (in this case are exactly the same)

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