It is a folding 6 rotor helicopter, inspired in X6 helicopter.i would like to build in polyethylene technical plastic, it is light, shock resistant and easy to work with my cnc mill.propellers are in a circle of 500mm diameter, i think best option in order to use standard RC parts is to use 6 x 12" counter rotating propellers.3 (counter rotating) propeller of 12" have an 8% more surface than 4 propellers of 10" (like typical quadrotors)Probably 14" propellers are better in order to get more performance but i think is not possible to find very low Kv motors with the necessary low power and low weight.Any idea are welcome!jlcortexnmine.com
Not necessarily.
Usually you use Props with the same size, but different pitch. The upper blade sould have good zero-speed abilities, but the lower one is in the air stream, so you want to compensate this by more pitch.
Since it is not all that easy to get counter rotating pairs, you will need to take what you can get.
The only props I know that have the feature are the APC SF 12". They come in both 3.8" and 6" pitch, as well as in counter rotating pairs.
However, they are quite heavy and require a motor with a lot of torque.
Your 17.5% rule is a mainly theoretical value. normally, you would want the propellers to be as close together as possible, to take advantage of the shearing effect. But then - depending on air flow speed and propeller geometry - you may get resonnance effects between the propeller blades - not good.
You realy have to experiment here.
I know what definitely works: It is an AHM 23-10 motor with .50mm² wire and EPP1045 props, distance about half a prop length (5" or so).
Those Props are not optimal, but hey - at $3.45 a pair - who's complaining about efficiency?
Nice to know!
Talking about this project, what about blade sizing? Why is lower blade smaller than upper one? Is it because of the air-flow generated by the upper one that i need a smaller one at the bottom?
Do you know about efficiency vs rotor distance (talking about coaxial)? I read that if the distance between the 2 rotors (talking about coaxials) is 17.5% of rotor radius you get near double efficiency, true?
Thanks again, and apologize my english
It is not an evolution, but a separate development.
Ususally, a fixed pitch coax setup is calculated at 1.6x the single rotor version. Meaning that 2 rotors side by side provide a lift factor of 2 - in co-axial mode only 1.6. There are quite a number of aircraft using this setup. Check the TU-95 and the Shackleton. Also read up on Kamov helicopters.
Coaxials are usually
Thank you very much!
I already found this one: http://aeroquad.info/bin/view (that seems to be the evolution)
but it is a quad rotor project and i'd like to build a tri coaxial rotor copter.
i will look better into it and come back when i bit more skilled
Do you know which model of copter will be better? tri / four / six rotos?
Anyone with some good link about fixed pitch coaxial application? (of course interested in math model)
Thanks
Hello,
I'm interested in building an UAV like this. Can someone point me to some good projects? I' looking for:
-Reading to start from (basic concepts and more)
-Technical details such as parts to use (engines, blades, controllers...)
-MATH MODEL!!!
I'm computer science's student and i'm going to develop this as thesis so i need a lot of help! :)
Thanks
Oh, almost forgot:
I am using the Armokopter board on this one.
BLCs are from hobbycity. I won't use those again - they are cheap ($13 each), but quite pooly done. One needs to remove the BEC-parts and reroute 2 signals to the Atmel. I did 8 so far, and I have a bout 1.5oz worth of surplus solder!
Comments
Here´s mine, by the way!
https://www.youtube.com/watch?v=JHxYQHeMD6A
Usually you use Props with the same size, but different pitch. The upper blade sould have good zero-speed abilities, but the lower one is in the air stream, so you want to compensate this by more pitch.
Since it is not all that easy to get counter rotating pairs, you will need to take what you can get.
The only props I know that have the feature are the APC SF 12". They come in both 3.8" and 6" pitch, as well as in counter rotating pairs.
However, they are quite heavy and require a motor with a lot of torque.
Your 17.5% rule is a mainly theoretical value. normally, you would want the propellers to be as close together as possible, to take advantage of the shearing effect. But then - depending on air flow speed and propeller geometry - you may get resonnance effects between the propeller blades - not good.
You realy have to experiment here.
I know what definitely works: It is an AHM 23-10 motor with .50mm² wire and EPP1045 props, distance about half a prop length (5" or so).
Those Props are not optimal, but hey - at $3.45 a pair - who's complaining about efficiency?
Talking about this project, what about blade sizing? Why is lower blade smaller than upper one? Is it because of the air-flow generated by the upper one that i need a smaller one at the bottom?
Do you know about efficiency vs rotor distance (talking about coaxial)? I read that if the distance between the 2 rotors (talking about coaxials) is 17.5% of rotor radius you get near double efficiency, true?
Thanks again, and apologize my english
Ususally, a fixed pitch coax setup is calculated at 1.6x the single rotor version. Meaning that 2 rotors side by side provide a lift factor of 2 - in co-axial mode only 1.6. There are quite a number of aircraft using this setup. Check the TU-95 and the Shackleton. Also read up on Kamov helicopters.
Coaxials are usually
I already found this one: http://aeroquad.info/bin/view (that seems to be the evolution)
but it is a quad rotor project and i'd like to build a tri coaxial rotor copter.
i will look better into it and come back when i bit more skilled
Do you know which model of copter will be better? tri / four / six rotos?
Anyone with some good link about fixed pitch coaxial application? (of course interested in math model)
Thanks
I'm interested in building an UAV like this. Can someone point me to some good projects? I' looking for:
-Reading to start from (basic concepts and more)
-Technical details such as parts to use (engines, blades, controllers...)
-MATH MODEL!!!
I'm computer science's student and i'm going to develop this as thesis so i need a lot of help! :)
Thanks
The other pics of the Fold-Down are in the Armokopter forum.
I am using the Armokopter board on this one.
BLCs are from hobbycity. I won't use those again - they are cheap ($13 each), but quite pooly done. One needs to remove the BEC-parts and reroute 2 signals to the Atmel. I did 8 so far, and I have a bout 1.5oz worth of surplus solder!
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