Cox .020 Pee Wee, gotta say - not a fan

rsv1cox Mon Aug 29, 2022 9:42 am

Perhaps I shouldn't make a judgement on just one example but.........

I have ran untold numbers of other Cox engines but I have never been interested in the .020's. Neither fish or fowl to me. Not the ubiquitous Cox .049's or the exciting .010's. Just that middle child that gets less attention.

First, that starter spring on this example is just useless. Way to strong and near impossible to get over the propeller. Seems they changed in in later? (top) editions.

Cox .020 Pee Wee, gotta say - not a fan P1013975

Just a little background. I found these to put on the Silver Lining. One is new, presently installed on S/L, this one probably new but shows signs of being mounted. I removed the tank to rotate the cylinder 90 degrees and inspected the reed (mylar star) which is fine.

Yesterday I fueled it with Cox 25% opened the NV 2 1/2 turns (recomended) and got weak runs off the prime. Tried quarter turns either side with the same result.
Nothing! Removed the fuel tank to inspect the reed and the tank was dry! What!

Rotated the cylinder upright and put it back together and tried fueling it again, as before fuel running all over the tank. Looked closer, the fuel tube was covering the small vent hole right beside the filler not allowing fuel to enter the tank. Give me the old double stackers!!!

Got some smaller tubing, the stuff that Bernie sells and filled the tank. Primed and flipped forever. Forget it, gave up - dinner time.

Back this morning. Topped off the tank, 2 1/2 turns, prime flip, prime flip. Finally it started running backwards. Didn't care! Wasn't running sloppy rich or lean fine, just leasure. Needled it both ways trying to get that nice Cox scream. Maybe a minute and a half. Never happened, not much difference lean or rich. Didn't bother to tach it.

Cox .020 Pee Wee, gotta say - not a fan P1013977

Check that starter spring. Caveman. Wen's Rotormatics put it to shame.

Cox .020 Pee Wee, gotta say - not a fan P1013976

Gave up. Loosened the tank screws to drain the rest of the fuel out. There wasn't any.

And to think I have three more of these on my .020 Tri-motor. Sad

Marleysky Mon Aug 29, 2022 11:49 am

Hmm, not the old saying "Big engines Big problems, Small engines Small problems" Your "new" starter spring is missing the hex driver/spring catcher. It's a plastic piece fits between the prop driver and prop, has a slot for the "U" bend of the spring to catch on. You'd have to measure the flats across the hex to see if the ones for the 049 would fit. Not sure if I have one to check.

Searched and found this:
https://www.coxengineforum.com/t14712-pee-wee-020-snap-starter-plastic-part

and this

https://www.coxengineforum.com/t8694-cox-snap-starter-spring-with-cam

rsv1cox Mon Aug 29, 2022 12:05 pm

Marleysky wrote:Hmm, not the old saying "Big engines Big problems, Small engines Small problems" Your "new" starter spring is missing the hex driver/spring catcher. It's a plastic piece fits between the prop driver and prop, has a slot for the "U" bend of the spring to catch on. You'd have to measure the flats across the hex to see if the ones for the 049 would fit. Not sure if I have one to check.

I have several of those, all on .049's. Did not realise that they came on .020's? All my other Pee Wees do not have that feature and all are double stackers fill/vent tubes.

No flats on this drive washer.

Removed the thing and positioned it where it would do the most good.

Cox .020 Pee Wee, gotta say - not a fan P1013978

Cox .020 Pee Wee, gotta say - not a fan P1013979

Cox .020 Pee Wee, gotta say - not a fan P1013980

sosam117 Mon Aug 29, 2022 12:15 pm

Yep, missing that little plastic part that locks on to the hex driver on the front that is pressed onto the crank shaft.
Most of the time, those get lost, and you just can't purchase just that item separately.
I know, I have purchased Cox engines with that plastic part always missing.

Cox .020 Pee Wee, gotta say - not a fan Cox_0415

Cox .020 Pee Wee, gotta say - not a fan Cox_0416

Luck would have it that Burnie (Cox International) has some of them for the Cox .049.

Cox .020 Pee Wee, gotta say - not a fan 009_co11

Cox .020 Pee Wee, gotta say - not a fan 011_co11

Bad part is Burnie and Matt do not have any for the Cox .020 available.

So, Ditch the snap spring on your engine and get a standard spring starter that hooks onto the prop.

As for the other problems.
Check over the entire engine carefully for dirty in the same places that you would with the .049
When running, that little .020 will scream just as well as any other Cox engine.

Best of luck.

p.s. Love those little screamers! Flying

rsv1cox Mon Aug 29, 2022 12:22 pm

Thanks Mike, still wouldn't work, no hex drive washer, so why the heavy spring.

Both advertized as "new" never used. I can attest to that.

Top engine has the hex drive but no clutch.

Cox .020 Pee Wee, gotta say - not a fan Nib_0210

Cox .020 Pee Wee, gotta say - not a fan Two_co28

sosam117 Mon Aug 29, 2022 12:27 pm

Marleysky wrote:Hmm, not the old saying "Big engines Big problems, Small engines Small problems" Your "new" starter spring is missing the hex driver/spring catcher. It's a plastic piece fits between the prop driver and prop, has a slot for the "U" bend of the spring to catch on. You'd have to measure the flats across the hex to see if the ones for the 049 would fit. Not sure if I have one to check.

Searched and found this:
https://www.coxengineforum.com/t14712-pee-wee-020-snap-starter-plastic-part

and this

https://www.coxengineforum.com/t8694-cox-snap-starter-spring-with-cam

Yep, that was me on that 1st posting looking for the plastic part for a Cox .020 snap spring starter.
The engine came with one of those U-control planes and would make it easy for a youngster to start the engine by just cranking the prop backwards and then letting the prop go.
Just like the Cox car I had years ago where you had the car on the ground then backed the car up, then lifted off the ground and the engine would turn over (spring starter).

Anyway, never got the plastic part.
Ordered some parts from Matt and Burnie and a Cox .020 regular spring starter for the .020 and took off the snap spring off the .20 (threw it in my Cox parts drawer) and installed the regular (normal) spring.

sosam117 Mon Aug 29, 2022 12:44 pm

rsv1cox wrote:Thanks Mike, still wouldn't work, no hex drive washer, so why the heavy spring.
Both advertized as "new" never used. I can attest to that.
Top engine has the hex drive but no clutch.

The clutch part probably fell of the hex drive and "was" rattling inside the box.
It then probably fell out of the box and got lost.
I have many .049 with the plastic clutch and don't bother leaving the clutch on the hex drive just because they fall off.
Initially, the plastic might have a tight fit on the hex driver and loosen up over the years?
The engines with the clutch (plastic part), I store that lastic part with the wrenches under the engine along with the instructions so that clutch part will not fall out and get lost.

As for "new" never used. I have found that small particles from the carboard boxes are in the intake (venturi).
New or not, I like to completely go through the engine and carefully check and clean the engine.
These little guys don't like dirt.
I even use a fuel filter (Sullivan's crap trap) on my fuel bulb to fill my engine to make sure I fill up with no dirty fuel.

sosam117 Mon Aug 29, 2022 12:50 pm

The photo you have of the Cox .020 has the spring in the 6 o'clock position.
I have some of those springs at that position as well as the spring at the 12 o'clock position.

Cox .020 Pee Wee, gotta say - not a fan Happyd14

Cox .020 Pee Wee, gotta say - not a fan Happyd15

Those are only for where you want to engage the prop?
For me, the one at 6 o'clock is good if you mount the engine sideways.

rdw777 Mon Aug 29, 2022 2:35 pm

Bob, Looks like you have a big prop on in the running picture?…. Maybe just the angle….PeeWee’s like a smaller prop to really spin up…I’m using a 4.5 x 2 on the Guppy glider (17K) and bench running a PeeWee R/C with a 3.125 x 3 - three blade (19K)…
25% fuel…

Yes, They are a little more finicky than a Bee but handle nicely when settled in… you’ll get’er … Thumbs Up

rsv1cox Mon Aug 29, 2022 3:19 pm

Mike, it looks like yours has at least a hint of a hex drive (gold) behind the drive washer. Mine has nothing. No hex, no need for the spring.

Robert, you have a point. It was swinging a T/F 5 1/4/2 the closest prop I had on hand at the time. I could have used the 4.5/2 that came with the boxed example but wanted to keep it "new." Since, I found a 4/2.5 that I put on it. One extreme to the other and will try that. Both are marked "Thimble Drome 0.20 engines only."

Left it upright, I think half my problem was flooding in the horizontal position. I built a needle for it, but somehow out of a box of .020 needles I got the one that didn't fit, so a do-over.

Cox .020 Pee Wee, gotta say - not a fan P1013981

Cox .020 Pee Wee, gotta say - not a fan P1013982

I'm determined to fly it, either my son or me. That tall grass thing.

706jim Mon Aug 29, 2022 7:46 pm

I spent a lot of time running Pee Wee 0.020's. NEVER used a spring starter!

Why carry all of that extra weight for something that is not needed?

GallopingGhostler Tue Aug 30, 2022 3:32 am

rdw777 wrote:Bob, Looks like you have a big prop on in the running picture?…. Maybe just the angle... Pee Wee’s like a smaller prop to really spin up… I’m using a 4.5 x 2 on the Guppy glider (17K) and bench running a Pee Wee R/C with a 3.125 x 3 - three blade (19K)…
25% fuel…

Back in 1973, I found out learning to fly single channel with my Pee Wee powered 27" Top Flite Ken Willard's R/C Schoolboy, that a Top Flite white nylon 5.25x3 prop powered my plane at the same flight speeds but gave me an extra minute of flight. The Pee Wee is a little torquer. Otherwise, flights are very short with about a minute and a half per run.

Only thing about the T/F nylons is they were notoriously out of balance, so I bought a prop balancer. It used two double edged razor blades as the balancing beams and a special prop axle, bracket mounted to a small piece of wood. I religiously balanced the props by sanding the back side of the heavier blade, which probably contributed greatly to my success in using the larger prop.

Plus, the T/F props were more sturdy than the Cox competition props (only ones available at the Navy Exchange at the time), and significantly cheaper. After breaking a couple Cox 4.5x2 gray props, I was sold on the T/F's.

I continued using the same props on my 20" T/F Ken Willard's R/C Roaring 20 (downsized Top Dawg) with many successful flights, and also with my later Ace R/C Littlest Stick.

OTOH, I would not use a 5.25x3 prop on my Tee Dee .020, it likes to really rev.

Regarding the extra weight of the spring starter, I had two C/L aircraft I mounted Pee Wee's on, Walt Musciano's 18" Scientific Hellcat and T/F's 18" full body molded sheet balsa Zero, but those were also rated to normally use a .049 engine, which is heavier. On the R/C's, you have the batteries as ballast, and so, the minuscule extra weight of the starter wasn't a problem either.

rdw777 Tue Aug 30, 2022 6:12 am

Jim, I’m still cheating using the spring starter lol!

… But I can see how a reliable PeeWee could start with just a flip… I’ll try that next time… Ol’ bent cylinder is still running fine by the way…. It’s the thinnest of the thin wall (early) so I think the focus on precision tolerance was among the highest…

George, I’ve read about the torky-ness of the PeeWee but have not tried it…. Sounds like a pleasant way to fly for that application… Sort of Texaco like…

rsv1cox Tue Aug 30, 2022 6:52 am

After a failed attempt to solder an extention wire on the needle (did you ever try to hit the head of a needle with the tip of a soldering gun while your hands were oscillating at about 120 cycles PM......) or a keyboard key for that matter Smile

. I put a drop of epoxy on the needles head and used that. I had already filed a slot in the needles head.

Balance point is a little more aft than it originally was, no starter on the engine and flaps/ailerons added. I could angle the landing gear forward about 20-30 degrees.

Cox .020 Pee Wee, gotta say - not a fan P1013986

Cox .020 Pee Wee, gotta say - not a fan P1013985

Cox .020 Pee Wee, gotta say - not a fan P1013984

This thing is done. Finished!! No more to be heard about it until and if it flys.

MauricioB Tue Aug 30, 2022 12:57 pm

Hello everyone, I leave you my comment and experience with the Pee Wee .020
Of the motors that I have tried, the Pee Wee turns out to be quite critical when it comes to its correct operation, some things influence the movement of the flap valve itself, causing the motor to not work regularly.
The metal seat or metal tank makes the flapper valve more unstable in its position, while the plastic base of a helicopter makes the flapper valve much more firm and in position, which gives it more regularity in the flow - march .
So I learned the following.
The 4.5 x 2 prop or three blade Cox prop causes the motor to spin many times and the flapper valve tends to move more which makes the motor shift more easily i.e. it becomes more erratic .
The propeller that gives greater stability to the operation of the engine is the Cox 5 x 4.
It is better to remove the starter spring, since in many occasions it vibrates with the revolutions of the engine, it starts a vibration tone that causes the flaper valve to move and as a result the running engine also becomes unstable.
Conclusion:
Use a Cox 5 x 4 propeller
If you notice the above while running, remove the spring from the starter, start it by hand or use a suitable starter.
Do not extend the regulation needle, the longer it is, the more vibration and generating instability in the engine. Use a removable extension piece, such as a ballpoint pen.
These are two videos of my Pee Wee marches.
In flight, he wears a helicopter tail plate.

rsv1cox Tue Aug 30, 2022 2:53 pm

Thanks for responding Mauricio, excellent tutorial on the operation of the Pee Wee.

I never thought of using a piece of plastic tubing to extend the needle or perhaps a spring that could be removed after it's running properly. BTW, that's the scream that I was familiar with and was looking for. Smile

And, how well your homemade throttle works. Looks like your engine has the lighter starter spring with less turns and you were using a three bladed propeller as indicated on the tach.

I think that I have seen your second video before. Amazing that you fly that close to the ground at those speeds. You must have been using a remote tank at eight plus minutes of air time.

I appreciate your comments and advise.

Bob

Gracias por responder Mauricio, excelente tutorial sobre el funcionamiento del Pee Wee. Nunca pensé en usar un trozo de tubo de plástico para extender la aguja o tal vez un resorte que podría quitarse después de que funcione correctamente. Por cierto, ese es el grito con el que estaba familiarizado y estaba buscando. Smile

Y, qué tan bien funciona su acelerador casero. Parece que su motor tiene el resorte de arranque más ligero con menos vueltas y estaba utilizando una hélice de tres palas como se indica en el accesorio.

Creo que he visto tu segundo video antes. Increíble que vueles tan cerca del suelo a esas velocidades. Debe haber estado usando un tanque remoto a más de ocho minutos de tiempo de aire.

MauricioB Tue Aug 30, 2022 9:22 pm

I'm glad the contribution is helpful. Here I leave you some screenshots of where you can see how I use a plastic pen to adjust the needle, in this case it is a Cox Medallion .09.
The tube goes in, twists and adjusts the needle, and then pulls out.

Cox .020 Pee Wee, gotta say - not a fan Pen10

MauricioB Tue Aug 30, 2022 9:28 pm

So dear Beto, enjoy a couple of Pee Wee .020... Beers

GallopingGhostler Wed Aug 31, 2022 11:43 pm

rdw777 wrote:Jim, I’m still cheating using the spring starter … But I can see how a reliable PeeWee could start with just a flip… I’ll try that next time… Ol’ bent cylinder is still running fine by the way…. It’s the thinnest of the thin wall (early) so I think the focus on precision tolerance was among the highest…

I'm following the discussion on the merits of going starterless, but personally, have never found any problems with the snap spring starter. It made firing up the Pee Wee easy. Glad to hear, Robert, that your fixed Pee Wee is running fine. I had one of those early Pee Wee's, nothing wrong with them nor the later ones in the 1970's.

rdw777 wrote:George, I’ve read about the torky-ness of the PeeWee but have not tried it…. Sounds like a pleasant way to fly for that application… Sort of Texaco like…

They would say that the Pee Wee is a miniature Baby Bee. No, it is not, it is more like a miniature Black Widow with its dual bypass ported cylinder. Leroy Cox knew what he was doing when he debuted the Pee Wee. It was an instant success, well liked by free flighters. People like Ken Willard helped to sell the engine with his series of rudder only designs sold by Top Flite and featured in the various modelling magazines.

Since the T/F white nylon 5.25x3 prop is no longer available, it would be interesting to see what other props may prove worthy to fill the gap. It would take some trying and experimenting with what is currently available. I've heard, purchased some, but haven't tried them yet, Bullnose electric props. I've heard that they are sturdy enough to handle the rigors of glow flight. They come in odd sizes too, used for quad copters.

Props now as slim pickings. Tower Hobbies (Horizon) has the APC 5.5x2 prop available. I don't know how suitable that would be without trying.

rdw777 Thu Sep 01, 2022 3:43 pm

George, That is an interesting analogy comparing a PW to a BW and I believe you are right… Of course the dual cylinder porting is a given but I got curious about PW’s venturi size and came up with about .050 compared to the BW’s .082…. The PW is only 41% of the BW’s displacement but has a much larger Venturi (relatively)…. So maybe it’s a miniature Black Widow-Plus…

andrew Thu Sep 01, 2022 5:14 pm

Robert,
In this case, I believe you would want to compare the cross-sectional area of the venturi rather than the diameter -- the cross section should give a better measure of air flow capacity. For the Pee Wee with a diameter of .050, the cross section area is approximately .00196 sq. in.; for the BW venturi, the area is about .00528 in. sq. Using these values, the Pee Wee venturi then comes in close to 37% of that of the BW, more in line with the displacement ratio.

a--

rdw777 Thu Sep 01, 2022 7:42 pm

Good catch Andrew, Yup, Things change pretty quick when considering total area… I came up with .00306 area for a Bee with .0625 Venturi… Kind of neat to see them laid side by side in that way….Would have been fun to listen to some of the Cox engineers on design thoughts…

Robert

GallopingGhostler Sat Sep 10, 2022 7:46 pm

I haven't done any measuring of venturi cross sectional area, but the Pee Wee was an instant hit, providing power in the region of the weaker earlier .049's. Hence this is another reason why I like to think of it being more of a mini Black Widow versus a mini Babe Bee.

706jim Sat Sep 10, 2022 11:21 pm

The Pee Wee was adorable 60 years ago and is to this day. Cute, rear needle valve, colourful and cheap. And for the most part, a really good runner with a lot of power.

Pee Wee 0.020 not a fan?

Not me!

GallopingGhostler Sat Sep 10, 2022 11:57 pm

The Pee Wee is a very user friendly, easy to start engine, when the right plug voltage (1.5), right fuel (25% nitro and 20% oil at least half Castor), and right prop (well balanced 4.5x2 - 5.25x3) are used. I always used the earlier snap starter. The other was said to lose about 300 RPM on the .049's due to spring drag against the plastic ratchet catch. Probably ditto with Pee Wee.

With my 1/4-A RC's, the Pee Wee's started right up after 2nd or 3rd flip, once you get the initial needle setting correct.

They are a really useful engine (as they would say on Thomas the Tank Engine). Laughing

Cox .020 Pee Wee, gotta say - not a fan Edward10

Photo from http://thomasfriendsreviews.blogspot.com/2013_01_01_archive.html
Episode "Edward the Very Useful Engine"

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