SERCEFLYER

My goal was to turn a 6X3 prop on a Cox Pee Wee 020. IT WORKED!!! I used Bruce Matthew's advice and "Texaco'd" the hell out of it: added 3 extra shims and used 5% nitro fuel. I was able to lean the needle out to a solid "purr" at around 8000 RPMs:

Here's the set-up:

engine: Cox Pee Wee 020 with 3 extra copper head gaskets (4 total)
prop: Cox Thimble Drome 6X3
fuel: Sig Champion 5% nitro with extra 2 oz of castor oil per quart

RUN TIME: 165 seconds (with a typical set-up, I found runs to be 90 seconds)
TACH READINGS: 8460, 8400, 8430

This should give me about 3-4 oz of STATIC THRUST. I'd like to power a rudder-only Guillow's Fairchild (approx 5.7 oz wet, wing area 96 in/sq ft). What do you think? Will it work?

Thanks.

Tom @ Buzzard Bluff

I think you'll love it. I don't think I've ever seen Joe Wagner run anything BUT a 6x3 on a Pee Wee. At one of the early Little Rock Small Steps he, Steve Staples and I agreed to bring single channel models the next year. Joe appeared with one of his 'Starling' designs with a Pee Wee wearing a 6x3 in the nose and it flew great even tho it is a relative heavyweght, all-sheet design compared to what your end use will be. Tom

DICKEYBIRD

Groan.... So, now you're gonna tell wonderful Pee Wee stories to try to make me drag mine out from under the workbench from where they belong? I swore off of the dang things years ago....they hate me!

Purring along at 8000 does sound appealing though. I've always wanted a reduced size, stick 'n tissue Laumer Twin Lizzie to play around with at the schoolyard. I still have a NIP Pee Wee R/C cyl/piston/sleeve set! NOW you've gone & done it!

BMatthews

Glad it worked out for you. Have you tried it with a 7x3 yet? As for powering the Fairchild I suspect you're in the ballpark. It may even be a bit strong yet for "scale" like performance. Try the 7x3 and be prepared to work with a total of about 3 to 4 degrees right thrust to compensate for the prop torque.

At these fuel flow rates cleanliness is very important. If you notice it acting up now and then and a needle removal and flush fixes it then consider filtering your fuel through a coffee filter.

A Twin Lizzie with such an 020 would be a real treat for stuff like this. Dickey, you KNOW the dark side is calling....

Tom @ Buzzard Bluff

You know you want to DB. You've just been skirting the issue for years. Why else would you be hoarding that Pee Wee conversion set? And now we all know it so you might as well get busy. If you'll quit wasting time you can have it at Small Steps.

SERCEFLYER

Dickeybird,

I have to admit: there was a big smile on my face when I leaned out the needle valve and the Texaco-style Pee Wee 020 settled into a steady purr. I think the 4th (!) shim was the trick. With only 3 shims, my tach readings were in the 9000 range. At that point the engine sagged and was a bit erratic. That 4th gasket reduced compression just a tiny bit more and tamed things down.

Everyone seems to say that Cox engines love nitro. I honestly didn't think the Pee Wee would fire up with just 5% nitro-- but it did. A lot of projects need the speed and power of a high RPM run. For a light, built-up Guillow's model, a Texaco-style engine set-up makes a lot more sense.

Thanks for the kind words. I really enjoy reading your posts and have learned A LOT from them. I'd love to hear about what you can do with a "tamed" Pee Wee.

George

DICKEYBIRD

Another groan. I'm having trouble getting motivated and finishing my u/c project before S.M.A.L.L. Now if I could just figure out how to use this new lathe to finish the thing up!Anybody that knows me knows how slow I am! Takes me 2 weeks to figure out how to cram 300 sticks into a project that really only needs a few scraps of sheet!

Yup, someday I WILL get a Pee Wee to run decently.

Tom @ Buzzard Bluff

Yeah-----go ahead, rub it in. Speed demon! I can't even count the sticks in that time frame.

If I ever get unstuck from the rut I'm in I'm planning on trying the product backplate engine from the heli starting with an unpressured balloon tank. If that doesn't work I'll ask you for advice.

BTW, my favorite Pee Wee powered model so far is Fred Reeses' Buttercup. I think it's disgustingly cute. I started putting it back in service a couple of weeks ago and managed to fry the monocote hinges when reshrinking the tail surfaces so now I'm just disgusted. I.m waiting to get over my peeve before I touch it again.[>:]

DICKEYBIRD

You talking about the round-ish orange/yellow plastic backplate gizmo? I have a couple of those myself. I was able to trim them down to a rectangular shape and drill 4 holes with the same spacing as the stock Pee Wee backplate so I could interchange them on the same firewall. I was hoping to build a lightweight twin with them but the project died due to apathy.

Ragwing

My Feedback: (2)

For a while I've been toying with propping down PeeWee's so I'm glad to hear from someone who has actually done it-it sounds great!

On the backplate issue, has anyone tried to make their own backplates? The sky copter backplates are nice, but somewhat hard to come by. I hate the idea of drilling through the original tank to ad an external fuel source, and I'd like to get away from the weight of the integral tank. However machining one out of aluminum might not be any lighter. Has anyone tried to modify a product engine backplate to fit a Peewee? It would require a little lathe work, but the nice part would be that the needle valve components would already be in place.

Just a thought,

Derek

Tom @ Buzzard Bluff

Yup, I think it has a finer needle with a better seal. As a stricctly subjective opinion I think the Pee Wees suffer more from leaks around the needle valve threads than the larger reedies. I seem to recall you also saying something about a finer needle thread on the referenced product backplate.
That's the current plan plus mounting it on a stand-off spaced to allow replacement with the standard tank-mount if the idea doesn't work. (all plans subject to change after a nights' sleep or even a nap)

That apathy feller is a real killer. I can't count the # of concepts in the shop that died in mid gestation as a result of his evil machinations. Do you think we can get him in front of a grand jury and get an indictment? He seems to be becoming more dangerous as I age too.
As a strictly thought provoking concept (see reference above concerning sleeping) how 'bout a Fred Reese Simple Cub built from the fan-fold insulation, so beloved of the electic crowd, with the outer finish composed of silkspan adhered with water-based varnish? If (most fraught with hazard 2 letter word in any language) it comes out as light as I want to think then a Pee Wee on a 6x2 or 6x3 should fly it in a scale-like manner.
I've had good luck with the silkspan/water-based varnish technique for almost 20 years now and I think it would add a lot of strength used in place of the thin layer of ABS plastic that comes on the fan-fold. Plus it does allow a nice finish to be applied.
Jes' brainstormin' Bossman. Tom

SERCEFLYER

Bruce,

What? A 7X3 prop on a Cox Pee Wee? OH THE HUMANITY!!! Are you serious? What RPM's would be appropriate? Should I stick a 5th (!) shim under the head?-- I'm running out of 'em. Any other advice? Would such big lumber damage the ball joint or con rod?

Anyone with other Pee Wee 020 "Texaco" experience?

George

BMatthews

Hey, it's running smooth now with the 6x3 so you're past the ignition timing problems so why not try it? It'll cut down the RPM's a bit more and reduce the thrust slightly.

At one point with the SAM 1/2A Texaco event they were running 10 inch props on the engines and getting up around 8 and 9 minutes run time on the 8cc Black Widow tank. It was these crazy long runs that forced the rule about an 8 inch prop MAXIMUM diatmeter for the event. I never went that far but I was running a thinned down 9x5 on my engine for a while and getting a bit more than 6 minutes out of the larger tank. Since they cut the tank size back to the Baby Bee standard and the prop to 8 inches I only get a 4.5 minute run.

If they can run 10 inch props why can't the PeeWee run a 7? Don't be so cheap. Buy another glow head for the gasket if you need to ...

johnvb-RCU

My Feedback: (1)

Bruce, were they running the 10" props on models operating under the current US weight/area rule, ie 16oz models?

Here in Aus most guys run 7" or 8", quite often electric, props in 1/2A Texaco. But we don't have the same minimum weight rule, so models tend to be around the 11-12oz mark. Also I've heard tell that flying conditions here are different from the US in that it takes a bit of power to punch through the boundary layer which lives anywhere from 200ft upwards.

Dunno, but 10" props sound very attractive to me, and I don't believe we have a maximum prop size rule here.

JVB

BMatthews

Yes, 8 oz/sq ft to be exact. But yeah that usually ends up being between 16 and 19 oz or so depending on how much wing area the model has.

A 12 oz model with a 10 inch prop would NEVER come down. [X(]

fritzke

My Feedback: (1)

Once, In my crazy teen-age years, I screwed a PeeWee to the front of my workbench, stuck an old wood TopFlight 13-3 "R/C" prop (remember those?) on the front and fired it up. It ran, but I shut it down after 30 seconds or so. But it was running! Look at the old planes from the 60's, they used 10 and 12 inch props on .15's and .19's all the time. Longstroke torque is SO out of fasion now!
(That PeeWee was probably doing about 2000 RPM!)
Dave

SERCEFLYER

OK Bruce--- I did some more experiments turning big props on the Pee Wee.

A. I first put a 5th gasket under the head and tried a run with the Sig 5%.

Engine: Cox Pee Wee 020 with 5 head shims total
Prop: Zinger Wood 7X3
Fuel: Sig Champion 5% with extra 2 oz/quart of castor

RUN TIME: 5 min 40 sec !!!
TACH READINGS: 3510, 3510, 3480

NOTES: It was very tough to start the engine. I had to keep the glow plug on for a long time to get things hot enough to sustain a run. The run was erratic with lots of "sputtering." Also, I noticed that with 5 shims the head was leaking a little bit.

jessiej

[Yup, someday I WILL get a Pee Wee to run decently.]

I got one to run quite well once, on an .020 replica FF. It absolutely screemed from the time it started untill I stuck my finger in the prop while starting the timer.

Aside from those few seconds of quality running my experience with post Thermal Hopper reedies has been fairly abysmal[:'(]. Obviously some sort of curse.

jess

BMatthews

Go back to 4 shims and try again. Also I suspect one of the shims got jammed in the threads and that's where your leak is coming from. The power and RPMs should rise as well once you fix the leak. I suspect most of your new found ills were due to the leaking. But 5 minutes 40 seconds....[X(] I must say that's beyond anything I was expecting.

For these sorts of RPM's you don't need a big club like prop like a Zinger. Find one of the new electric series APC 7x3's and try them Much finer looking. I know from past experiments that you can expect about an 8 to 10% gain in RPM's from using a thinner and more streamlined prop then the Zinger baseball bats.

It sure looks encouraging. And I'll bet the exhaust sounds very scale like now. No more of that tiny engine shrieking.

jboy381-RCU

after reading this thread...i tried a 5X3 prop with two shims...ran good and steady...also tried a 6X3it ran but it sputered a lot...i then took the prop and cut it down to 4X3...this gave the best and longest run...was getting around 13,000 rpm,and a run time of 3.5 minutes...i know it now a 7X4,but i'm going to put it on a 6OZ. model...with the wide blade i think it's putting out more thrust than a 4.5X2...


john

SERCEFLYER

John,

Great to hear that you are running your own Pee Wee experiments. What fuel were you using? Nitro content is also real important in getting the ignition timing right. What model do you plan to stick the Pee Wee in?

Thanks for the data,
George

jboy381-RCU

i'm running 25% fuel...i think this after noon i'm going to try 10%...i'm not sure what the plane is...i know that it flys great on the 4.5X2...i'll post a picture of it this after noon..

john

SERCEFLYER

OK, here are some more experiments in taming a Cox Pee Wee 020: I went back to 4 shims total under the glow head, and I changed the fuel to Sig Champion 10% I was amazed by the previous 5 min 40 second run, but I'm trying to find an engine set-up that's easy to start and consistent. One problem with the previous set-up was keeping the glow element nice and hot. If I didn't set the needle just right, the run would last about 20 sec, slow down and die. I had to keep the batteries connected for about 20 sec to get things nice and hot. Here's the new set-up:

engine: Cox Pee Wee 020 with 4 head shims total
prop: Zinger 7X3
fuel: Sig Champion 10% with an extra 2oz/quart of castor oil

RUN TIME: 4 min 45 seconds !!
TACH READINGS: 4680, 4680, 4740, 4560, 4680, 4530
CALULATED STATIC THRUST: about 2.25 oz

NOTES: Start up was a little easier but still a bit tricky. I got better RPMs and the run sounded less erratic. The prop still has to get to a certain speed to maintain enough heat on the element between ignition cycles-- at least that's my guess.

jboy381-RCU

here are some pic fo the plane and the fat prop...one of themis a little blury but you can see the prop...

john

SERCEFLYER

OK, this time I changed fuels altogether to COX SUPER POWER FUEL (15% nitro and 25% castor). My goal was to get a hotter run. It worked.

ENGINE: Cox Pee Wee 020 with 4 total head shims
PROP: standard Zinger 7X3
FUEL: Cox Super Power Fuel

RUN TIME: 4 min 55 sec
TACH READINGS: 4410, 4170, 4500, 4470, 4440, 4530
CALCULATED STATIC THRUST: approx 2.25 oz

NOTES: It was much easier to start the engine and get it nice and hot. I couldn't lean things out more without sagging, though. A consistent run with a great scale-like sputtering purr.

I'm really happy with the run times-- 5 min on the stock Pee Wee tank!! I always thought I'd set up an external tank-- but, 5 min is enough for me. With this engine set-up you are giving up speed and thrust for a slow, low-thrust, LONG-LASTING run. This set-up wouldn't make sense for a lot of applications, but for a 96 sq in 5.5 oz model, why not?

I have nothing against electric RC, but here's a set-up that make sense for a light, slow park-flyer. But there's nothing that compares with hearing and seeing a little Pee Wee turning a gigantic 7X3 Zinger baseball-bat-of-a-prop.