http://www.MyGeekShow.com

After flying the raptor several times with the 8"x4" prop, we felt like we were stuck in 2nd gear not harnessing the full potential of the motor.  We decided to fly the raptor with several different props with a range in diameter and pitch.  This was a first step in figuring out how we will more scientifically analyze the benefits and losses associated with various props.  For now we were making qualitative observations and monitoring speed using the RCSpeedo iPhone app (definitely transitioning to APM2 on board sensors and telemetry for future analysis). We used APC props with results as follows:

Changing Pitch:

8"x4" - 54 mph, motor seemed to handle this size well, ranging through different RPM as increasing throttle to max

8"x6" - 57 mph, felt faster at lower throttle, but top half of throttle range felt over burdened.

8"x8" - no speed recorded, flew just fine but definitely too much prop for this size motor.

Changing Diameter:

6"x4" - 37 mph, felt like 1st gear

8"x4" - see above

9"x4" - flew but unfortunately plane battery was too low to make observations. 

We will revisit this again in the future! Anyone with recommendations about how to model prop dynamics please point us towards any available resources that you trust.  Thanks!



See you Wednesday,

-Trent & Nick

--Raptor & Shrike--
Battery: 20C 2.2Ah Sky http://www.hobbypartz.com/77p-sl2200-3s1p-20c-3333.html
Servos: T-Pro 9G http://www.hobbypartz.com/topromisesg9.html 
Motor: Optima 450 2220-1800KV http://www.hobbypartz.com/75m55-optima450-2220-1800kv-2.html
ESC: Exceed RC Proton 30A http://www.hobbypartz.com/07e04-proton-30a.html

Produced by Trent & Nick in Arkansas, USA
Main Camera: Panasonic HDC-TM900K
Video Editing: iMovie

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Comments

  • Alain: Its the throttle cut off on our Turnigy 9x from ParkeFlyer.

  • No problems,

    Glad to know you've a throttle safety switch. Is it on the plane? Or some programming on the RC Tx (that's what I did on mine) if I may ask.

    Cheers

    Alain

  • Gary: I've heard this before, but can't wrap my head around the theory, do you know of a resource where I could learn more about small prop & high RPM vs larger prop & low RPM?

     

    Greg: Aweseom! I'll have to mess around with this tool!

     

    Alain: Good call... we did have the throttle safety switch on, but that is still not perfect, and we didn't show it, so that is a good call. Thanks!

  • Hello,

    I really like and enjoy your show, but

    Please, please could you avoid changing props while the battery is still plugged... That was very scary to watch and I think that's definitely not an exemple to show...

    Beside that, keep up the good work

    Have a great day

    Cheers

    Alain

  • Excellent video. Why don't you try this?

  • Moderator

    You want a low KV motor and a big prop.

This reply was deleted.