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Cox Engine of The Month
Cox PeeWee Micro Speeder
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Page 4 of 4 • 1, 2, 3, 4
Tobaiies- Silver Member
- Posts : 80
Join date : 2020-10-30
Age : 22
Re: Cox PeeWee Micro Speeder
Yes per prop pitch speed 177 kmh / 110 mph in a pass.
- down wind pass can exceed prop pitch speed on a windy day
- diving and leveling off quick can give a brief gps reading of 222 kmh
The plane only needs to fly forward at 222 kmh for a brief moment to gain a locked in peak reading.
To get closer to actual ground speed the plane would have to dive less to avoid spiked readings.
A circuit pattern with high top steady shallow dive that keeps the peak rpm up right as it passes the camera.
Can try full length prop to retain some thrust - N reduce the wider prop tips to pick up much needed rpm.
Consider profiling the airfoil after back cut the trailing edge should be reshaped into a airfoil's trailing edge.
The blades are like wings - as a experimental effort a bit of washout sanded in / may improve tip pitch / stability.
- down wind pass can exceed prop pitch speed on a windy day
- diving and leveling off quick can give a brief gps reading of 222 kmh
The plane only needs to fly forward at 222 kmh for a brief moment to gain a locked in peak reading.
To get closer to actual ground speed the plane would have to dive less to avoid spiked readings.
A circuit pattern with high top steady shallow dive that keeps the peak rpm up right as it passes the camera.
Can try full length prop to retain some thrust - N reduce the wider prop tips to pick up much needed rpm.
Consider profiling the airfoil after back cut the trailing edge should be reshaped into a airfoil's trailing edge.
The blades are like wings - as a experimental effort a bit of washout sanded in / may improve tip pitch / stability.
1/2A Nut- Top Poster
- Posts : 3536
Join date : 2013-10-20
Age : 61
Location : Brad in Texas
Re: Cox PeeWee Micro Speeder
Here are a few flights and comparisons from today, think a little faster again.
Tobaiies- Silver Member
- Posts : 80
Join date : 2020-10-30
Age : 22
Re: Cox PeeWee Micro Speeder
Yes much better results the prop work is paying off!
Did you get GPS readings?
Tach rpm readings / prop pitch speed:
?x4.1N - 29,392 @ 1.02 mins. / 114 mph - 183.5 kph
?x4.7N - 27,051 @ 2.02 mins. / 120 mph - 193 kph
?x3N - 31,573 @ 5.48 mins. / 90 mph - 145 kph
4x3 - 28,667 / 81 mph - 130 kph
Best vid yet
Did you get GPS readings?
Tach rpm readings / prop pitch speed:
?x4.1N - 29,392 @ 1.02 mins. / 114 mph - 183.5 kph
?x4.7N - 27,051 @ 2.02 mins. / 120 mph - 193 kph
?x3N - 31,573 @ 5.48 mins. / 90 mph - 145 kph
4x3 - 28,667 / 81 mph - 130 kph
Best vid yet
1/2A Nut- Top Poster
- Posts : 3536
Join date : 2013-10-20
Age : 61
Location : Brad in Texas
Re: Cox PeeWee Micro Speeder
1/2A Nut wrote: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.
Thanks for the tip on hot plug, Brad, I swapped my medium hot with a hot one and with 1 shim only, and the rpm has clearly improved. It may be somewhere where the stock COX head runs it i.e. 24k on the ground with 20% nitro and the 3 bladed COX prop. I will continue the exercise with some 2-bladed props too...
balogh- Top Poster
-
Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Cox PeeWee Micro Speeder
Good to hear the prop loading of the 3 blade has woke up with 1 head shim and hotter plug.
Did you oil the glow plug threads and seat area prior to install?
Med. plug would be good and robust for high nitro above 35% +
Did you oil the glow plug threads and seat area prior to install?
Med. plug would be good and robust for high nitro above 35% +
1/2A Nut- Top Poster
- Posts : 3536
Join date : 2013-10-20
Age : 61
Location : Brad in Texas
Re: Cox PeeWee Micro Speeder
Thanks. Brad, I always make sure head and plug seal perfectly..
balogh- Top Poster
-
Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Cox PeeWee Micro Speeder
This was a 'thing' back in the 1/2a pylon days using the Cox grey Competition props!
1/2A Nut wrote:Yes per prop pitch speed 177 kmh / 110 mph in a pass.
- down wind pass can exceed prop pitch speed on a windy day
- diving and leveling off quick can give a brief gps reading of 222 kmh
The plane only needs to fly forward at 222 kmh for a brief moment to gain a locked in peak reading.
To get closer to actual ground speed the plane would have to dive less to avoid spiked readings.
A circuit pattern with high top steady shallow dive that keeps the peak rpm up right as it passes the camera.
Can try full length prop to retain some thrust - N reduce the wider prop tips to pick up much needed rpm.
Consider profiling the airfoil after back cut the trailing edge should be reshaped into a airfoil's trailing edge.
The blades are like wings - as a experimental effort a bit of washout sanded in / may improve tip pitch / stability.
Time for V4
Today I started building the fourth generation.
First I sketched the parts, everything is a little smaller. The wing moves slightly forward to improve the center of gravity, while the tail is slightly longer to further increase stability. The fuselage is narrower again, I hope I can pack everything I need in it
After that I pretty much did everything as usual.
Before I can install anything in the fuselage, I need to make the wing to see where I have room to install the servo
First I sketched the parts, everything is a little smaller. The wing moves slightly forward to improve the center of gravity, while the tail is slightly longer to further increase stability. The fuselage is narrower again, I hope I can pack everything I need in it
After that I pretty much did everything as usual.
Before I can install anything in the fuselage, I need to make the wing to see where I have room to install the servo
Tobaiies- Silver Member
- Posts : 80
Join date : 2020-10-30
Age : 22
Re: Cox PeeWee Micro Speeder
Do you sand an airfoil into the 3mm thick wing, or just leave it as a flat board and set the aspect ratio to a few degrees??
balogh- Top Poster
-
Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Cox PeeWee Micro Speeder
Yes, I sanded a profilebalogh wrote:Do you sand an airfoil into the 3mm thick wing, or just leave it as a flat board and set the aspect ratio to a few degrees??
You just have to make sure that it's sanded evenly everywhere.
Tobaiies- Silver Member
- Posts : 80
Join date : 2020-10-30
Age : 22
1/2A Nut- Top Poster
- Posts : 3536
Join date : 2013-10-20
Age : 61
Location : Brad in Texas
Re: Cox PeeWee Micro Speeder
Tobaiies wrote:I've made some progress.
The wing is now only made of 3mm balsa, but is still very stable.
I really like this design and all the progress you have made.
A couple of these planes would be fun to race on a 150 foot course with 2 poles.
TD ABUSER- Gold Member
- Posts : 407
Join date : 2020-11-01
Age : 69
Location : Washington
Re: Cox PeeWee Micro Speeder
yes that would be awesome!TD ABUSER wrote:Tobaiies wrote:I've made some progress.
The wing is now only made of 3mm balsa, but is still very stable.
I really like this design and all the progress you have made.
A couple of these planes would be fun to race on a 150 foot course with 2 poles.
Tobaiies- Silver Member
- Posts : 80
Join date : 2020-10-30
Age : 22
Re: Cox PeeWee Micro Speeder
I see you use LiPo battery? What is the voltage and capacity in mAh? Do you need a voltage regulator to step its voltage down for the servos?
balogh- Top Poster
-
Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Cox PeeWee Micro Speeder
Very nice planning and building Tobaiies!!!! I’m sure it will be very speedy and will be looking forward to the video….Please share what servos and receiver you are using as well if you don’t mind….Good luck with first flights !!!
rdw777- Diamond Member
-
Posts : 1716
Join date : 2021-03-11
Location : West Texas
Re: Cox PeeWee Micro Speeder
Thanks! I think it will be a while before the first flight.rdw777 wrote:Very nice planning and building Tobaiies!!!! I’m sure it will be very speedy and will be looking forward to the video….Please share what servos and receiver you are using as well if you don’t mind….Good luck with first flights !!!
I'm using 3.5 gram servos from an old E-flite model and a Futaba R3004SB receiver.
Tobaiies- Silver Member
- Posts : 80
Join date : 2020-10-30
Age : 22
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