Load factor on 2b is 6859. Divide that by sqrt2 gives 4851. Get the cubed root of that you get 16.9. so yes, 17 inch diam. (Keeping the same pitch for both)

Hi, you make good points, and there is a huge amount of debate on the forums on the topic of PLF. Most RC pilots change diameter or pitch choice depending on how they want the plane to perform, so even after these calcs are done there is still room for manoeuvre. The debate continues...!

You would have to play with the numbers to get both sides to match. In some cases this could mean using a different pitch to get equality.

That's good work, thanks. I'm glad my shorthand method gets such similar results.

Hi, there's A LOT on rcgroups.com on this subject and the two methods I've presented here are the best approximations from my research on this. It will get you very close, particularly the first (longer) method, and you can play with pitch etc. to get the best performance for how you like to fly the model.

I didn't think this video had anything to do with RC Cameras. I thought this video was for people who's RC Airplanes always come with 2 blade props, but the Life-Sized, Real-World counterparts always have 3 blade Hartzell Props. They want to convert for realistic, scale looks, but retain flight capability and efficiency. Most of these type of people are definitely doing this mod or they wouldn't even want the plane anymore, lol.

Some planes need smaller diameter propellers for ground clearance, to avoid any chance of the blades clipping the ground. True that more blades weight more, but the propeller diameter is reduced, so it compensates.

Hi, it's not possible to perform a direct ratio calculation due to the effect of the cubed root. But the maths are unit independent, so using the same equations will give you the correct diameter anyway.

Hi, give this a go and see if it helps : rcplanes.online/calc_thrust.htm

Hi, more blades offer a little more ground clearance which I wanted for the model I'm building (a Slow Poke). It's a tail-dragger so the nose will tip towards the ground on take-off. Also, for the style of the model I felt that 3 blades would look nicer. In general a 2-blade is more efficient but 3-blades can be a little quieter. For a more in-depth look at the pros and cons see this site: hartzellprop.com/are-more-propeller-blades-better/

Hi, it's propeller load factor. The principle is to keep the load factor the same whilst changing the number of blades.

Hi, I've just done the calculation. From what you say I believe you have a 5-blade 10x4.5 prop and want to use a 6-blade prop. By my calcs the load works out at 9000, giving a diameter of 9.6 inches. Same pitch of 4.5. If you go down to a 9 inch blade the pitch will need to be 5.5 to keep the loading equal. Hope this helps.

Thank you so much, but actually 1045 recommend propeller it's a 2 blade and I want to use a 6 blade probably this can could be more understandable, so i don't know ... thank you so much

Hi, these pilots may have done this as the lower pitch will produce more pulling power from standstill, but sacrifice top speed. Pilots can choose from a range of propellers to suit their powerplant. The video shows how to do a straight conversion from 2 to 3 blades (and vice versa) but some pilots may choose higher or lower pitches to change the model's flying characteristics.

Hi, the only thing you need to change is N, the number of blades. The formula would be D x D x D x P x SQRT(4-1). In my example, a 2 blade 9x6 would equate to a 4 blade 7.5x6.

Many thanks Conor 👍👍

@@StartingOutInRC how about 20x10 2blade what is the right number for 4 blade same pitch

The speed of the craft and rpm will be low as you'll add 1inch diameter. But the thrust will be higher

You can use the same equation, just keep the diameter the same. I get the feeling it'll require a big change to the pitch value to balance the equation.

Hi, I don't use those types on my RC planes so can't advise you on that, sorry.

It will keep going up until the batteries run out! Keeping it under control, which you should do at all times, is down to the range of your radio equipment.

@@StartingOutInRC typhoon h pro can't fly over 122m while dji drone's can fly about 5000m. Why it happens? Isn't there any mathematical theory?

Typhoon H is limited to 122m by its software.

I'm using my degree as an aeronautical engineer wisely!

@@StartingOutInRC you can tell how you write/draw and the math equation 🤣👍

You can use the same RPM. The equation gives you a 3-blade propeller that will place the same load on the motor as the 2-blade

@@StartingOutInRC if I don't use the equation?

If you reduce the diameter by one then you can use the same RPM.

@@StartingOutInRC I mean if I just add another blade without changing anything else then what will be the rpm?

That will depend on the available power. There's a good discussion here on the factors that affect large vs small propellers. www.rcgroups.com/forums/showthread.php?28219-Big-prop-low-rpm-or-small-prop-high-rpm

There are alot of videos with single blade heli and planes you just have to have a counter weight

where did you get "educational" from.

@@jch8175 its "NOT!" an "entertaining!" video! its an educational one! one that educates the person watching it and not wasting your time by entertaining you like at "VEGAS!" were we all sing and dance to the drug music/medication music! he clearly is not involved with "NATIONAL GEOGRAPHIC!" were you are completely "entertained" with "beautiful" pictures of the world while playing "RELAXING!" drug music while somebody describes what is happening to you while you are all "messed-up!" from the "relaxing" music! its also difficult to here what a person is saying and its very annoying for no "APPARENT!" reason! this is just a very brief answer to your question! EVER BEEN TO COLLEGE! NOBODY "LECTURES" WITH MUSIC GOING! the word "lecture" means you have to "THINK" with something called "THOUGHTS" about what the person is saying and understand them! with national geographic your simply told the plant is "GREEN!" their are no thoughts! their is no thinking! but they are a very prestigious! organization! for "WHAT THEY DO!" they entertain you!

For the second part of your question you should read Alex Gouthro's comment which describes very well why propellers are shaped like they are. In your first question you have to think about the load the propeller puts on the motor. You can gain small efficiencies by changing pitch or number of blades but the motor may struggle. Adding an extra blade should make the propeller quieter for the same performance, producing 3 smaller pressure pulses rather than 2 bigger ones.

@@StartingOutInRC Thanks so much for the explanation!!! Happy New Year 2020!

I've noticed it too (!) and I only do it when making videos, it's a strange habit. I'm now making a conscious effort to reduce it 🙂

@@StartingOutInRC It's not that bad.