Cox PeeWee Micro Speeder

Thank you for the thumbs up Robert and Eric, happy to see Tobaiies .020 speed projects!  


   

Found out today the Kamtechnik prop plate adapter works with the carbon Cam 4.7x4 speed prop.
Has a snap fit for precision centering, note the stud bolt has a end point socket head uses a .050
allen wrench to lock it down and to avoid seized threads. The grade #8 black oxide bolt sits snug
in the threads with less slop than the stock bolt that came with the valentine .020 spinner nut.

The prop as is should work with the .020 engine with it's constant pitch blades, lower weight and
less bulky at the hub compared to the APC 4.1x4.1. Cam 4x3 does not work with the thrust plate adapter.
The Cam 4.7x4 certainly as a cut down speed prop will do 100+ Left alone will generate notable thrust.

Thank you for posting the pics!

Very nice, good looking speeder, how is the weight with gps?

Each build / tested shows a path to the next honed down version to fly faster.

The plane flew great, the cooler glow plug tested made 4x3 / 28,670 rpm best noted peak.
CAM 4x3 best peak hit 29,063 rpm with the other plane and stock plug.

For the .020 I use hot plugs and 25% nitro.
What is the ready to fly weight of this version?
I oil the plug threads and adapter threads to help seal from leaks when assembling.
The stock APC 4.1x4.1 will need some backcut or can try extra head shims.
I like rubber bands to protect the wing in a crash or bad tumble.

3 bladed prop -  what turbo plug heat range tested best?

How did 1 shim do?
Any tests with 2 blade props?

balogh wrote:Brad I have only the COX 2 bladed props for 020 size engines (my APC-s are larger)  that the TD spins way slower than the 3-bladed. So my benchmark is set by the 3-bladed and I compare the heads using that prop only.

Try 1 shim for more rpm

The adapter was set up and tested for the more widely used Cox 4.5x2 prop.
The compression was adjusted to serve with one head shim as many folks
may not have spare shims to add.

Absolutely did not give up or settle with numerous prototypes tested until the adapter
was honed to make more rpm than stock. Same engine and prop saved for only testing.  


 

Yes the volume from the glow plug element hole makes an impact.

Some glow plug designs have larger holes than others, some are really bad.
I use OS Gold Plugs to insure good elements and conductivity for starting.

Key is to ensure you have a good seal and the seat for the glow plug
has conformed to the plug manufactures design. I double check after
the engine has been heated up from running.

Sometimes the element needs to be plucked up out of the hole some.
I use a needle to carefully raise it up.

Congratulations the plane has indeed made a faster pass!
Do you have a photo of the prop with back cut?


To reach 222kmh / 138 mph would need a prop pitch rpm of 35,560 rpm not counting prop slip or if down wind pass.

At 1:53 minutes the best pass hit 28,262 rpm making a prop pitch speed of 110 mph or 177 kmh
20% castor and 35% nitro should keep the rpms on point throughout the flight. Beats your old record
of 156 kmh / 97 mph pass + 21 kmh / 13 mph with the new design thus far.

Engine starts off strong but then something happens dropping rpm, some possible reasons:
Cooling down in flight creating a rich fuel state.
NV is moving (opening up a bit due to vibrations) can seal and hold with fuel line.


Setting NV quick to peak rpm with the plane level and launching before it heats to peak thermal state prompting
a richer NV setting to hold peak rpm in the hand. If launched before it peaks and sags will cool down in the air enough
to balance / set for best thermal state / rpm in flight.

Castor oil helps stabilize the peak thermal state on the ground so there is less flux between in flight additional air
cooling and thermal state on the ground. 1/2A fuel helps reduce hunting for the best NV setting for in flight rpm.