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» Revamping my Lil Roughneck
by balogh Today at 2:48 am

» Cox .01 /.02 /.05 /.09 /.15 Speed Planes
by 1/2A Nut Yesterday at 10:16 pm

» 0.049 reed motor efficiency
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» Strange, this Spitfire engine has two holes
by Mark Diedrichs Yesterday at 3:57 pm

» 049 Black Widow tuning
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» "Free" display case is finished
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» 2018 to 2019 CEF Run What YA Brung UNLIMITED speed contes (CLOSED)
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» Show and Tell
by rsv1cox Thu Aug 22, 2019 8:54 am

Cox Engine of The Month
August-2019
fredvon4's

"Tee Dee .049"



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

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  getback on Fri Aug 09, 2019 8:26 am

That Baby was Screaming !!!! way to GO Brad !! Small Cox Logo Very Happy
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  balogh on Fri Aug 09, 2019 12:59 pm

Wild run, Brad! You mean it was a stock SPI TD 051? Then the only thing I still miss is a good manifold between the cylinder and the tuned pipe..suppose gkamysz will soon sell that?
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Fri Aug 09, 2019 8:40 pm

Thank you Gents !! Thumbs Up

Yes stock .051 with SPI
Yes it is fast for a simple TD engine this is fantastic!
Yes the manifold / headers will end up in a production run for sure hard to pass up this part should sell well.
Key reasons it works so well is good seal no leaks / maximum flow in and out of the engine.
I need more of them one for bench runs testing engines / props  more for flying projects and boats.

I plan to do some more flight tests this weekend now the intentions will be for actual speed runs
meant to out perform the Nano III.
See here modified props just for the Nano X engine and pipe use.
4.3 x 5.5 est. 29.6k rpm / 154 mph pitch speed
4.2 x 6.5 est. 28.8k rpm / 177 mph pitch speed

I am about to blow away the Nano III best doppler pass of 138 mph.
Note the bar cut version is a trick to relieve torque requirements adding more rpm.
The 6.5P prop by nature was made more beefy at the hub in my case I don't need the beef.
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Imag0211

Another trick is using TD .020 bullet spinners does add top end rpm and less vibrations to the engine.
These inset into the prop hub keeping the mass as close to the prop plate as possible.
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Imag0212



Best pass thus far in run two 33,672 / 143 mph pitch speed.

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  aspeed on Fri Aug 09, 2019 9:06 pm

I thought it was finally on the pipe when you mentioned the prop fluttering. I could be wrong. You could have launched earlier and picked off that pesky dog.
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Happy RE: Cox.01/.02/.05/.09/.15 speed planes

Post  66 Malibu on Fri Aug 09, 2019 9:44 pm

That is one big league impressive run on the .05 !!!!
You must have an ultra secret method of keeping the rod/piston ball joint alive !!!!
Your R&D work always intrigues me and would probably really warp my brain if I understood all you do for those results !!!
Great Job !!!!!!
Steve...………..
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Fri Aug 09, 2019 11:21 pm

1/2A Nut wrote:Best pass thus far in run two 33,672 / 143 mph pitch speed.

Awesome! Where at in that run (time) was the best pass?

I think I fly quite a bit closer to myself than you do (your smarter Very Happy ), you might be getting lower numbers than your really going. Very Happy

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Fri Aug 09, 2019 11:23 pm

Thank you Oz & Steve Thumbs Up  
Yes tricks many tricks that add up to no engine damage.
I will list a run down of methods after my results this weekend.  

Yes it was on the pipe a lot this second run, what I should have said in the vid
is it is not steady continuously on the pipe
. The NV was close enough to cause
it to jump on the pipe with any amount of diving but once level it was hit or
miss on staying there. I imagine the NV was about 2 clicks off.  I am not
running pressure. So first run was set to inure no leaning 2nd run was then
tuned closer to peak, in fact i purposely leaned it till it quit as shown on start
up to know where the stopping point is. The engine idles great and transitions
without dying on launch so happy there.  

Pressure may help to nail a solid NV setting. The pipe cools in the air what has
been learned is set it to peak on the ground to compensate. The cooler pipe in
the air extends the timing. What math's out at 30.8k rpm based on the estimated
sweet spot best MRP point is less in the air with a cooler pipe was kicking in at 28k +

The non bearing engine does not suit well with flexible prop tips hence the flutter.
The Fuji with bearings has got to 37k with no flutter but did flutter at time mainly
into the wind. So the simple fix is just use more ridge blades at the tips which the
APC props can provide. Note my custom mod props eliminate flutter by the nature
of their shape. To compare the look like small APC pylon  props now.

Example of a APC pylon prop.
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Lp088810

Oz I fly much closer too this was a maiden flight day I have only flown the plane twice.

Here is how I like to line them up when I have some stick time / gives good solid sound files.
The camera makes things look a bit further away most of this was 8 to 12ft on the close ones.
I have to line up far out and try not to move the surfaces much as it scrubs off speed.
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Sat Aug 10, 2019 5:01 am

--Oz-- wrote:
1/2A Nut wrote:Best pass thus far in run two 33,672 / 143 mph pitch speed.

Awesome! Where at in that run (time) was the best pass?

I think I fly quite a bit closer to myself than you do (your smarter  Very Happy ), you might be getting lower numbers than your really going. Very Happy


"RPM Gauge" for android phones.
I use this tool to get rpm it has been proven with my laser tach and photo cell types. You can also use
a youtube vid with someone using a tach and verify straight off the vid.
You just need to make sure the resolution is set correctly for low end and high end readings.
Observations to tell when the pipe kicks in with the 4x4.5 prop and the given NV setting and temp on the day of testing.
Another pass / reading showed it kicked in at 28.3k rpm and peaked at 32.9k
i use all the same tools to have constancy when gathering data, this will allow good choices when making changes.
The speed props will get a good review getting down to the nut cutting, once I find the best prop per software I will
take my tripod and radar gun and get results with that more to haul and set up but worth it if the best prop has been found.
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Vlcsna28
Note I posted the best pass on the other page a vid of it that pass was reviewed over and over until the peak reading
showed up 4 times I then recorded vid of the RPM Gauge and review the numbers as they popped up as it happens fast.
Hence the photo above. I have a GPS unit 14.6g but just no where to put it the fuselage is full no wasted space.
Flying close is fun but risky I use aluminum bullet spinners if the mass of the plane hits me at 130 mph it will impact
with the force of 81 lbs. per dry weight of the plane not fun lol. That's 81 lbs at the tip of the bullet spinner.
https://www.smartconversion.com/unit_calculation/Force_calculator.aspx
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Sun Aug 11, 2019 4:15 am

Perhaps the next plane will be called: NANO-15 MK II

Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Imag0215
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Imag0214

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Sun Aug 11, 2019 3:30 pm



Published on Aug 11, 2019
Nano X - TD .051 / 3rd Flight / Tuned Pipe APC 4.3 x 5.5
Best Pass 28,100 rpm / 146.3 Prop Pitch Speed
Now the fastest TD .051 3ch Plane bested Nano III
Best static 21,962 rpm / 114 mph pitch speed'
.147 hp - 110w / 7.3oz thrust
25" span 75 sq. in. wing / 8.2oz RTF
25% nitro / 20% oil  / SPI engine / no pressure tap
Kamtechnik turbo plug adapter
Kamtechnik prototype manifold and header
Small Cox Logo  Thumbs Up

Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Vlcsna30
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Vlcsna32
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Vlcsna31
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Mon Aug 12, 2019 10:57 am

141mph Clapping

On rcg there was a guy that modified the wave0scope program to output mph, however I could not find a copy, I even tried using the waybackmachine.com

I found this bit of good info on these model motors:
https://www.mh-aerotools.de/airfoils/cox_techinfo.htm
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Mon Aug 12, 2019 11:33 am

Thank you Oz! Thumbs Up

I use to have the MPH version on another comp was nice to not have to convert.
Another thing that was added down at the bottom was est. rpm. I wish there was
a sport camera with built in radar that would give continuous readings while filming.
As miniaturization continues to progress it is possible. There is a small radar gun out
right now that is the size of a cell phone in shape for ball sport use for baseball etc.
This is very good but only up to 130 mph.
https://www.pocketradar.com/products/introducing-smart-coach-radar-model-sr1100-with-free-shipping?gclid=EAIaIQobChMI8aCXv-P94wIVfv7jBx0RzAwmEAYYASABEgIhzPD_BwE

The radar gun I use now is this system:
https://shop.opticsplanet.com/bushnell-speedscreen-radar-speed-display-101922-wireless-radar-gun-screen-w-tripod-ca.html?_iv_code=BU-GA-101922-KIT1&utm_source=google&utm_medium=cpc&utm_campaign=plusbox-beta&gclsrc=aw.ds&&gclid=EAIaIQobChMI6_fy9uT94wIV0P_jBx0UCAayEAQYBCABEgLBzPD_BwE



This plane has been quite exciting for 1/2A flying. Down wind is blistering. Up wind
is better than the Nano III which is a very good plane as is. Rare I do a reduction build
to squeak out more speed, the .049 - .051 class engine deserves max effort to find out
what's possible with today modern gear. More folks fly this displacement than any other.
Really happy with the prop mods they are the key to tap into the nominal static power,
shape selection is everything. Yep seen that site thank you.

Small Cox Logo  Thumbs Up


Last edited by 1/2A Nut on Mon Aug 12, 2019 12:09 pm; edited 3 times in total
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  dirk gently on Mon Aug 12, 2019 11:46 am

Watched the video, seems to have been a video of clear blue sky, didn't notice any model.
Maybe I need to watch it again, but without blinking?
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Mon Aug 12, 2019 11:52 am

Lol Dirk Thumbs Up yes just a Sunday morning vid with some sunshine poking through the clouds. sunny

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Mon Aug 12, 2019 10:17 pm

Somewhere I saw 0.140HP = 104W, being electrical engineer and flying electric planes/quads, I am guessing this wattage number is just taking 1HP=742W / HP, is this correct?

So where does this HP number come from?
What is input wattage to make this output wattage?

As we know electric power is so inefficient (specially storage density). My quad burns 1800Wpeak on 4S (2100W on 5S), but does 0 to 84mph in 1.2 sec at 9g acceleration and weighs 430g (this is old school quad, they are now up to 14:1 thrust to weight).

I am just thinking if trying to do 130-140mph with 104W electrical watts is very impressive and not really easily possible with electric, to be fair, it might be possible and a great challenge. Very Happy But I am really thinking the 2 stroke nitro burning is using a lot more equivalent wattage, I could be wrong.

Considering our gas cars are horribly inefficient (way less than 50% converting fuel to motion), nitro is probably worse (I could be wrong), and 2-stroke cant be any more efficient, thoughts?

EDIT: Here is where I saw the MPH version of waveoscope (link is dead now) https://www.rcgroups.com/forums/showthread.php?867528-WAVEoSCOPE-English-Translation
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Tue Aug 13, 2019 12:51 am

Hey Oz,
1 HP equals 745.7w  / I round up to 746w

I use the same calc software for each engine on the bench and at the field so the
data stays consistent. I use watts as most who fly have done electric and the value
stands out more to easy remember. Standard Cox Tee Dee should at least make
80w with 15% nitro and stock props. The larger dia. props generally calc out to
more watts, it takes quite a bit of rpm to get the power numbers up with speed props.

- Again here is the link to the calc software:
http://www.godolloairport.hu/calc/strc_eng/index.htm

- Example:
Best static 21,962 rpm / 114 mph pitch speed'
.147 hp - 110w / 7.3oz thrust

GOOD Question how do I fly so fast on 110w.
- engine rpm unloads in the air must know what the engine can handle
- props are not stock I modify them quite a bit. (they are small)
- high pitch / just enough dia. / speed tip props
- the planes are smaller than they look simple clean low drag
- wing cord is just 4" wing tips 2" span 25" only 75 sq. in.
- nitro adds oxygen into the fuel also helps cool the engine
- methanol burns hotter than nitro
Many speed efforts made in this thread from .010 thru .09 thus far with vids.
I walk folks through the designs, parts and props.
Example:
Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Imag0217

Check out this out impressive speed for a mere 21w
A challenge you could do is: 1S 3.7v nominal charged to 4.2v
Loaded volts 3.85v x 5.45A / 21w


Published on Dec 4, 2017
NANO - TD .010 / 130.4 MPH - Best Pass Per Doppler
Prop 2.56 x 4N  / 30% Nitro:
Static 28,858 rpm / 109.3 mph / .028hp / 21w / 1.5oz thrust
Unloaded best pass per prop calc 133mph audio tach / 130.4 mph per Doppler reading
and best pass on this vid 35,184 rpm / 3oz RTF / 2ch  RC micro race plane.
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  gkamysz on Tue Aug 13, 2019 10:28 am

Electric airplanes are fast due to low drag. No cylinders, no pipes or anything else hanging out of the airframe. I think Brad could pick up significant speed simply by cleaning up the airframe. Bring the aileron linkages inside the fuse, the elevator linkage through the tail, some fairings around the engine, etc. I was flew some F5D electric pylon around 2000 when brushless became standard, but we were still running NiCd. 600-700W from the battery and 150+MPH.

When drag is low the plane can fly closer to pitch speed. It's also why CL speed is so hard. Line drag is huge. Line drag is about half of total drag for a 1/2A mouse racer.

Calculating power from prop RPM is not always very accurate. it all depends on the "prop constant" applied for a given prop. We all know and APC of a given size needs less power than a Master Airscrew. And even within a product line there are variations. Some things are just overlooked like the Graupner Super Nylon are actually metric and the inch sizes are rounded, so lead to bad numbers if used for calculation.
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Wed Aug 14, 2019 2:13 am

When I was looking at and talking about the wattage numbers in my post, I was thinking this:

1 HP equals 745.7w

1hp = work being done over time
the 746W is the electrical equivalent.
These numbers states nothing about system efficiency, only output power (work) being done,

I am going to take a wide guess, a 2 stroke nitro motor is 10% efficient. That roughly means it takes 7,460W of fuel energy (input) to produce 746W of output energy.

The best brushless motors are upto 90% efficient (maybe not hobby motors), but lets go with 50%. I am sure you see where I am going with this.  Smile
In your example you mentioned 0.147 hp - 110w, in this example, input energy would be 1,100W.

In this example: "Check out this out impressive speed for a mere 21w (this is output energy, input energy would be 210W)
A challenge you could do is: 1S 3.7v nominal charged to 4.2v
Loaded volts 3.85v x 5.45A / 21w"
This is input energy, apples and oranges.  Smile

By no way am I taking anything away from the impressive speeds your getting with tiny motors, excellent work!
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Wed Aug 14, 2019 2:42 am

Thank you Oz,
As a test you could set up a brushless motor to produce same static rpm of a given prop and IC engine.
Using a amp meter find out how much amp draw and voltage was needed to do the same work providing the
motor size is equal in weight or near too. Fuel tank weight vs Battery weight to estimate a 2 stroke
power equivalent. I have many engines / props bench tested on youtube to choose from. The goal would be
equal system weight: ESC / Motor / Battery vs Fuel / Tank / Engine and Throttle Servo for the RC carb.

Without a dyno the calc program keeps it's constancy with all my tests so I am able to see improvements and
comparisons. I will always state the results as my threads are for data storage and online sharing. The only facts
are in the build components physical measurements and the vids showing what the outcome of the total effort can do.
I would like to build a TD .15 plane next I need a manifold header yet to sort out the power and pipe length to fit with
a plane design. I have a small gps unit that will fit in a .15 size speed plane. Looking forward to taking ground speed
measurements with it and comparing to the software results.

I have wound 3 phase motors wye and delta terminations with 9 and 12 pole motors.
Back then 76 to 83% was about as good as it gets providing you don't over prop and the room
temps are cool. Some Go Brushless kits one, two stator and 3 stators / cd rom frames. Would be nice
to see more folks striving for small IC speed their approaches to the problems and displacements would be
entertaining and interesting.

E planes have more torque on the nose and can make anything fly fast. Prop blast from the IC engine
helps to keep the engine cool as I push the rpm up 30% more than what most folks fly at. Fiberglass
or carbon cowling could be used but typically increases the size of the frontal area in order to fasten
them, refueling and cleaning in the field would be a pain, as these belly lander's slide through patches
of dirt and rock. The summer heat is brutal on the grass by Sept. it's all burnt and brown thinned out
with exposed dirt so dry it shrinks up with open cracks some as wide as 2" The simple TD engine with
no bearings is not going to fare well covered up the heat will increase requiring a richer NV setting
loosing rpm and run time. The world needs a CNC crank case with bearings for the TD!

The elevator linkage is through the tail with the Nano II, Nano IV and Nano III and Nano X.
There is no room inside the fuselage for torque rods, these are very small planes the wings are held by rubber bands
to avoid wood and hardware damage on rough landings. If you crashed with torque rods sticking inside the fuselage
and the wing pops off there would be no clearance for separation. May rip up the gear, side of the fuselage, wing where
the rods would be inset into the wing. Note the width of the fuselage for size reference.
17mm / 18.5mm and 22 mm wide as shown in the photo, the Nano X is 26mm wide at the same referenced location.

Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Nano_110


Did you watch the 3rd test flight Greg?

I can handle about another 15% increase in speed, as is blinking is limited to
keep up with it as a 25" span. The field is plenty big but the plane is a dot in
seconds if not careful and orientation is fuzzy when turning it around if I let
it get out too far.
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Wed Aug 14, 2019 9:54 am

Here is a guy testing BLDC quad motors. Lots of good data (voltage/current/thrust/rpm/etc).
https://www.miniquadtestbench.com/motors/

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Wed Aug 14, 2019 3:37 pm

I took a common BLDC quad motor and punched in the data and hit calculate, but the thrust is only ~1Kg, should be 1.6Kg. Of course the prop that is used is not in the list (5050x3). So I adjusted the CF to get the thrust to read correctly, this is probably the mistake Shocked

31,982rpm, 15.3V, 49.8A, 763W (input)
In the output, it shows 1.093KW, i am screwing up somewhere, lol.

Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 26 Mqtb_d10
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Wed Aug 14, 2019 9:20 pm

Yes he uses mainly 3 blade props I gave up after checking 14 write ups all with 3 blades.
I use E props and flown some stock but quickly start to modifying them to suit the engine.

I do have solid data / vid on stock HQ Drone props the carbon blend 4x4.5 and 5x4.5 two blade props.
Have you used them?
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Wed Aug 14, 2019 11:00 pm

1/2A Nut wrote:Yes he uses mainly 3 blade props I gave up after checking 14 write ups all with 3 blades.
I use E props and flown some stock but quickly start to modifying them to suit the engine.

I do have solid data / vid on stock HQ Drone props the carbon blend 4x4.5 and 5x4.5 two blade props.
Have you used them?

My quad is 231mm motor to motor (diag) and is designed for 6" props, but the community found out 5" tri-blades have many benefits, they can change rpm faster, this makes reaction time quicker and better stability in the worst conditions (such as flying backwards through your own dirty prop wash in a trick or u-tun), also they generally dont need balancing even after being bent (and bent back) in a crash, this is a huge time saver. E.G. a bi-blade prop, once it gets bent, it is way out of balance, with tri-blade, barely.

When i run any 5" prop under 5 pitch, they are just slow on my 2400kv motors (top end, acceleration and grip in the corners), seems guys running 2600-2700kv tend to use under 5 pitch.

I have tried HQ props, they are good in the air, but really suck in the durability department, cost and visual orientation aid. I usually fly 12-18 battery packs back-to-back in the morning before work, its a pain to change props when your time pressed and the cost, just not worth it for me when I fly a 37 cent prop that performs in the air as good, takes a beating and much lower cost and the colors really help seeing the quad. I fly the KK5050x3 (kingkong)

OT: I seen a quad do 165mph (267kph) on YT.
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  --Oz-- on Wed Aug 21, 2019 6:30 pm

Here is some serious G's (sorry its electric) at 186mph Damn!
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  Surfer_kris on Thu Aug 22, 2019 2:18 pm

That's nothing Wink
Take a 12x24" prop and spin it up to around 27000rpm, that's good for about 280Mph:

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

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