18x6 VS 16x8 Prop RPM Testing - RC on Handmade Channel

For my next project - big RC Plane with gas 25cc engine I prepared 2 propellers:
Master Airscrew Classic 18x6 (first on video)
and
Master Airscrew Classic 16x8 (second on video)
Learning other people experience I found that both works good with 25cc engines.
This video shows real RPM for both propellers on conversioned 25cc WeedEater petrol engine, measurements done with digital tachometer from Hobbyking.
Results:
18x6 - maximum RPM is about 7000
16x8 - maximum RPM is about 7500, but this smaller propeller accelerates faster then bigger 18x6

[@2000351Ranger]

Exactly what I was looking for... Thanks for leaving the camera in the same spot. 👍

[@HandCraftChannel]

u welcome!

[@SammSheperd]

Interesting to compare directly and quickly the two props! Even with a higher pitch the shorter one sounded easier to spin. Also interesting is that the smaller one seemed harder to hand start with because it has less rotational inertia to act as a flywheel.

[@HandCraftChannel]

***** I cut off video with start attempts on bigger prop.Both are same hard to start. Engine was cold.

[@GibbonFPV]

Nice :)

[@MasboyRC]

You're using 4 stroke engine with diapraghma carburetor right?

[@tarassych]

no, it's 2 stroke but with electronic ignition

[@MasboyRC]

@@tarassych so cool.. i appreciate it 👍

[@munawarshah6860]

Sir, what is deference in between both propellers in phically

[@alanboston5811]

Barehanded ?

[@arunjangra4960]

How much thrust they can generate

[@HandCraftChannel]

this project never end with a plane built or any thrust tests, don't know sorry..

[@nealstephensonhiro72]

An online propeller thrust calculator shows 9 LBS for the small prop at that rpm, and 13 lbs for the larger at listed rpm.
Those are static values of course, and an airborne aircraft is dynamic, but it gives some perspective on performance. I'd guess in use, the smaller prop would accelerate to its top speed quicker , but at a lower speed than the larger prop. Speed here being the airspeed of the plane.

[@alanboston5811]

Barehanded ?!