Re: Cox PeeWee Micro Speeder

Tobaiies Sun Jul 17, 2022 6:29 am

haha, yeah, I'm getting a little scared too. Paranoid

I'll test it today Hand Shake

1/2A Nut Sun Jul 17, 2022 11:55 am

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.

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Tobaiies Sun Jul 17, 2022 3:29 pm

Here are a few flights and comparisons from today, think a little faster again. RC Plane

1/2A Nut Sun Jul 17, 2022 5:05 pm

Yes much better results the prop work is paying off! Thumbs Up

Did you get GPS readings?

Flying

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 Popcorn

balogh Mon Jul 18, 2022 6:22 am

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...

1/2A Nut Mon Jul 18, 2022 12:48 pm

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% +

Popcorn

balogh Mon Jul 18, 2022 3:28 pm

Thanks. Brad, I always make sure head and plug seal perfectly..

Mark Boesen Tue Jul 19, 2022 10:42 pm

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.

Tobaiies Fri Dec 16, 2022 4:30 pm

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 Laughing

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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 Huh...

Tobaiies Sat Dec 17, 2022 9:51 am

I've made some progress.
The wing is now only made of 3mm balsa, but is still very stable.

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Now only the linkages are missing. I hope the receiver and the battery will have enough space Laughing

balogh Sat Dec 17, 2022 9:56 am

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??

Tobaiies Sat Dec 17, 2022 10:01 am

balogh 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??

Yes, I sanded a profile
You just have to make sure that it's sanded evenly everywhere.

1/2A Nut Sat Dec 17, 2022 1:49 pm

Looks great Tobaiies, should provide improved performance!
Fast work getting this one built up quickly for all to see and enjoy.

Taking the overview photo can resize / shape the project and reveal a faster plane. Flying

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TD ABUSER Sat Dec 17, 2022 2:45 pm

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 Sat Dec 17, 2022 2:47 pm

thank you! I'm done, The RTF weight is 83 grams. Saved about 10% to the previous version.
I'm curious how the flight characteristics will change.

Fortunately, the space is not a problem, even better than before, the center of gravity is also easily adjustable.

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Tobaiies Sat Dec 17, 2022 2:50 pm

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.

yes that would be awesome! RC Plane

balogh Sat Dec 17, 2022 6:25 pm

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?

rdw777 Sat Dec 17, 2022 6:38 pm

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 !!!

Tobaiies Sun Dec 18, 2022 5:49 am

balogh wrote: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?

Its a 1S 3,7 Volt 240mAh LiPo from a little drone. With this i can directly go to the receiver and the servos.

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Tobaiies Sun Dec 18, 2022 5:54 am

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 !!!

Thanks! I think it will be a while before the first flight. Sad

I'm using 3.5 gram servos from an old E-flite model and a Futaba R3004SB receiver.

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