Cox .01 /.02 /.05 /.09 /.15 Speed Planes

I use a slip jaw wrench and rap the cylinder with leather to keep the fins in mint condition.
You could get a dremel cut off wheel and put some flat spots at the top of the cylinder.
Glow plug did not come loose in this test great little engine. I have two .09 medallions
two TD .09 RC with the mufflers and 2 TD .09. My first one was bought and flown back
in 1996 a TD .09 RC I used a pressure tap on the muffler it was a screamer and flew
a pylon type plane very fast.

Thanks fir the tips Brad. Before going to the surgery solution with the dremel - that, given my hand skilss just a tad better than those of the Australopitecus, I have a great chance to cause more harm than benefit with - I will try the slip jaw wrench...

I guess you mean the one with adjustable spanner distance used by plumbers?

I use something like this:


If you can find the ones like these no leather needed:
https://www.ebay.com/itm/ROBOGRIP-Cannon-Plug-Pliers-8-Inch-Robo-Self-Adjusting-Cushion-Grip-CHN-RCP8-/263249905282?_trksid=p2349526.m4383.l4275.c10#viTabs_0

The 2nd one seems safe without leather if the plastic jaws are wide enough to grab at least 3 or more fins at a time? I will go see in a DIY shop in my area tomorrow.

1/2A Nut wrote:.....

Do a weight check on your 7x3 Graupner prop. Compare to the NN glass prop at 6.1g
.....

The Graupner 7x3 is twice heavier, it weighs 12,86 grams...One would assume the prop weight impacts only the time the engine accelerates to top rpm, but it is only the airfoil (width, dia and pitch) of the prop that influences the top speed?

Weight also adds a bit to crankshaft friction, but would that really matter so much?

Through actual use and modifying many props and weighing comparing shapes and airfoils,
flying and recording rpm monitoring ground speeds in relation to my standing position:

- Rpm provides thrust.
- Low weight props can provide more top end rpm.
- Narrow props provide more rpm which increases their ability to provide thrust.
- Narrow props provide less thrust at the same rpm of a standard shape blade.
- Heavy props rob torque and rpm.
- Thicker airfoil robs torque and rpm but can provide thrust.

- Race prop flies faster than a stock prop.
- Race plane flies faster than a trainer plane.
- Narrow cord airfoil allows higher pitch props with the given amount of engine torque to work with.
- Thin airfoil lifts very well at high rpm's and wings lift better at higher speeds.
- Wings are like props reducing drag and weight always increases speed.
- Flying fast increases heart rate and produces adrenaline
- Flying fast retains more memories of those moments
- Flying fast makes you smile at some point during or after the flight.

Posted top vids speeds thus far:
Engine  / Speed / Prop / RPM
Cox .010 / 130 mph / 2.56x4 / 28.86k
Cox .020 / 122 mph / 3.37x4.5 / 28.59k
Cox .049 / 118 mph / 4.1x4.1 / 30.5k
Cox .050 RC / 139 mph / 4.22x5.5 / 26.65K
Fuji .05 / 148 mph / 4x4.5 / 36.75K (tuned pipe)
Sportswerks .05 / 161 mph / 4x4.5 / 37.71K (tuned pipe)
(pitch speed only no viable Doppler pass yet)
Norvel .061 / 108 mph / 4.2x4 / 28.6k (tuned pipe)
(far from done with this engine old data)
SH .07 / 120 mph  / 4.75x4.75 / 26.64k (tuned pipe)
(far from done with this engine old data 36" span wing)
Cox .09 / 144 mph / 5.25x6.25 / 22k

Great summary Brad as always,thanks!

Happy July 4th celebration to all of you CEF mates in the US!

Thank you I hope the information inspires you further.
Yes Happy 4th time over here thank you my friend, we are all gearing up for Wednesday!

Testing some new custom made bullet spinners for the TD .020
prior to this I would tap out Ron Valentines TD .010 spinners
using a threaded stud to fit the .020.  The dia. is spot on for
.020 props and has enough meat on the bone for an electric
starter to grab onto. Vibrations are knocked out with this type
of centered none migrating spinner with notable top end increase
in rpm over stock.


One of my go to E props makes great thrust 5.3oz and rpm to 95mph pitch speed.


Here shown with the stock grey prop.



       

balogh wrote:One would assume the prop weight impacts only the time the engine accelerates to top rpm, but it is only the airfoil (width, dia and pitch) of the prop that influences the top speed?

Yes, the weight of the prop itself will of coarse only act as as flywheel and will not affect top rpm. The Graupner props have a much larger area, wider tip-cord, and a much thicker foil profil, and that will certainly affect the rpm.

- Low weight spinners help the engine to turn up more rpm.
- Low weight everything always helps the engine to unload more.

Seen, heard the difference, proved it with my own engines / plane tests / flights and vids.
Only speed flying can clearly show differences, sport designs mask the varibles tried with
only mild sometimes hard to notice improvements tainting perspective.

The TD .010 with the least amount of torque showed me the proper path most clearly during
the variables I imposed on it a few years back. The TD .020 has been the second best teacher
which continues to challenge me to this day pushing for ways to improve the top end.

Will be bench testing this prop next and the new TD .020 bullet spinner.
Spinner and stud weight is 1.9g / the tapped out TD .010 bullet spinner is 1.4g
a tapped out stock TD .010 spinner 1.3g / stock TD .020 spinner and hex bolt 1.6g
I need to cut the thumb screw off the NV and put a thin / leaner nyrod extension on it.  
Forced perspective with the prop / spinner closest to the camera lens.

1/2A Nut wrote:Big improvement with a peaked NV to sing mode good and steady.  
Pic shows how much I had the window open for the exhaust breaths
better than with that extension on the muffler, in the field for flying will
have it fully open as shown in the previous post. Beast of a .09 for what it is.

If flown with that prop @ 26k down wind / 80 mph
Serious thrust / 2:1 ratio for constant speed in any direction will pull out
of the hand and bolt away like on steroids. The DART design was around 11.5oz
as I recall a leaner NANO design with a 6.5P speed prop could do 160 pitch speed
with a 1:1 thrust ratio. The pressure tap really woke this one up in combination of
less exhaust restriction. The spring steel ring can be removed if no need for sound
suppression, if left on can close off the exhaust port from air / moisture when not flying.

Static 20,914 rpm / 30.7oz thrust / 1.9lbs / .326hp / 243w / 64 mph pitch speed.

Very interesting!!
Friend have you tried making a pressurizer for this muffler?
Reference: corresponds to Cox .049 / .051

Thank you Eric it is a perfect fit for the .020 engine.
Mauricio I have not tried that muffler trick on the .049 muffler should work though.



Tested the new spinner and prop the engine ran very smooth no vibrations
centering of the prop and spinner was perfect! 102 mph pitch speed static!
Also used some nyrod tube as a exhaust diverter it seems to be griping
enough to stay so far. Muffler design needs a bit more barb on the end of
the exhaust tip to hold silicon tube. Added a bit more back pressure to the
tank engine was rock steady running. So far best speed in the air has been
122mph I hope this prop can bust the 130 mph barrier. Typical unloading
in the air with speed props is over 5 to 7k with the TD .020

Note at the end it runs steady then stops clean no erratic stop due to pressure in the line.





Previous test without the exhaust deflector:

Will try this modified 5x5E prop next cut down to 3.88x5N
Need to hit 3oz thrust static to pull out of the hand on windy days.
I decided to leave the thumb screw alone on the NV since it's in
front of the muffler still dirty but atleast a bit cleaned up the ridges on
the nyrod makes it easy to grip.

Comparisons of whats been tested vs this more proportional cord prop.

Per pic: 4.23oz of thrust at 96 mph pitch speed looks like the effort
to sculpt the prop to 3.88 x 5 has paid off well. Prop was well balanced.
20.1k to 20.45k: 95 to 97 mph pitch speed. Enough thrust to go vertical
out of site. Sorta looks like a APC prop now. Would be nice if APC made
a 3.75x4.75 proportioned like this for the TD .020 good for 21k static.
Took about 30 mins. to make this prop, sanding the cut side back into a
airfoil on the top side of the blades and balancing. Tough prop at the hub
will handle some not so good landings.

Duplicated out of carbon would be most worthy.

Break down of the bullet spinner sizes:



Can also retap the .020 spinner for small hub props with .049 engines.

1/2A Nut wrote:Break down of the bullet spinner sizes:



Can also retap the .020 spinner for small hub props with .049 engines.

Are those TD .010 bullet spinners available for sale anywhere?

Many Thanks,
=Adrian=

The TD .010 spinners are from Ronald Valentine here is his for sale page:

https://www.ebay.com/usr/wisolme?ul_noapp=true

Direct link only 3 left:
https://www.ebay.com/itm/Custom-Cox-Tee-Dee-010-0-16cc-Spinner-and-stud-Cox-Model-Engine/372376705377?hash=item56b3619961:g:jF4AAOSw4a1bU74n

You have to bird dog his page he puts up spares of his batched parts used on his custom engines.
He has made batches of them twice this year that I am aware of thus far. You must buy
and not hesitate as they go fast. Nothing is guaranteed to come back around for sale when
it comes to custom batched parts sometimes a few years go by before you notice more on hand.

Buys spares you can never do with just one, careful you don't over tighten or you will snap the
small dia. threaded stub. Go by feel once it butts up to the prop take your time and turn slow
till you have a bit of compression on the plastic prop. Not so much a issue with the larger spinners.

Pic is the .049 version in the link he has the wrong pic shown the correct pic is this one using soft steel studs



   

Saw this for sale on ebay .. lol on the bullet spinner!!!

Setting up for a tuned pipe on a TD one can use the cox car manifold and muffler.
Not as good as a custom made header that allows a better volume of exhaust flow.
If you whittle out the header at the manifold you can eek out a bit more performance.
See pics each showing required mods to set up the engine for pipe use.
Note rear facing exhaust port open and front blocked by the brass shim inside the manifold.
Shown with a 9.5" MRP



Interested in testing this engine with a Nelson plug to compare with the Cox high compression plug per vid. TD .051




Cox TD .050 / Profi Tuned Pipe / 25,193 Static - HQ Prop 4 x 4.5
Static 7.3 oz thrust / .132 hp / 99w / 107.3 mph /
9.3in MRP / 140 deg timing / Pipe math for MRP set for 25,215 rpm!
Fuel line was a bit big for 1/2A use /  pressure line was correct.
For flight prop HQ Prop 5x4.5  will unload near MRP and produce
est. 11 oz static thrust.  Non SPI / 20% oil / 30% nitro.

All aluminum frosty fuel tank for TD .020
Capacity 13.3cc /.45 oz / weight  5.6g
Functioning acro clunk / 2.2" L x .63" W

Beautiful tank Brad I wish I could have those aluminum capsules available near me..