I Need Help !
 

hey guys my name is mohamed and i'm student in the faculty of engineering .. aeronautics department ..

we were assigned to build a VTOL aircraft .. and unfotunately we don't know anything about rc planes so i was wondering if someone could give me some advice about what should we use ..

i think that brushless motors are the first thing to start with .. so i looked around for a while and i found this : http://www.nitroplanes.com/esbrcoset31b.html

this was the highest RPM/Weight ration i could find .. and it includes its controller which actually i don't know what it does :D

so that's all i know .. i'd be really grateful if someone could point me in the right direction about everything else .including RC controllers .. batteries .. motors ...etc.


thank's in advance

RE: I Need Help !
 

Hi Mo

first of all what is a VTOL??


Secondly, How much of a budget do you have?

Third, What is the purpose of this remote control device?

Really all i'm trying to say is GIVE MORE INFO

thanks

RE: I Need Help !
 

thank's for trying to help me RedGN ...

as i said before .. i'm a real newbie .. so i don't know exactly what you want to know :D


VTOL is short for vertical takeoff and landing .. kinda like a helicopter but with a different body shape ...


our budget is around 500$ .. but ofcourse .. the less expensive .. the better

we need the remote control to be able to control the speeds of the all the motors simultaneously and individually




waiting for your answer ...

RE: I Need Help !
 

VTOL - Vertical Take-Off and Landing

Healthy Boy - there are many designs of full size VTOL aircraft, (not that many have been successful) but not to many for RC.

As for electrics over glow motors, I don't know. Most of the VTOLs that I have read about for RC have all been electric.

Good Luck on your project.

RE: I Need Help !
 

hey bassfisher ...

but i did choose a brushless elelctric motor .. so i don't totally understand what you mean ...

RE: I Need Help !
 

What i would suggest to you is to but a electric Ready-To-Fly Helicopter and Rip it apart to get all the peices

A brushless motor - To turn your blades or whatever else you will use
A brushless ESC - Electronic Speed Controller, This way you can control the speed of the motor
A gyro- This will mix the tail rotor or opposition so your VTOL doesn't just spin around in circles
A receiver- this will accept the radio signals and convert them into electrical pulses to control things like the ESC, Servos, etc.
Servos- These are little geared motor used to move linkages for pitch and other things
A Transmitter- 4 to 6 channel , this is what you hold in your hands to control your VTOL. More channels means mor things to contol.

Hope this helps a little. But i would suggest you go to your local rc hobby store and maybe grab a few magazines just to get up with the lingo.

Good Luck

RE: I Need Help !
 

Just read your previous post .

Multiple motors need multiple ESC's, for brushless anyway.

Again good luck

RE: I Need Help !
 

thanks again RedGN .. that was some helpful info ...

i think that buying each piece separately would give me the ability to choose its specs. individualy .. for example i could choose a motor with a specific rpm .. and so on ..

for the stability .. our design is in the form of an equilateral triangle-shaped body .. which uses opposite moments from different motors to stabilize it .. the design actually requires 3 motors ...

so .. if i need 3 motors that generate a relatively strong thrust .. which motors would you recommend ? and also what battery and remote control should i use ?

RE: I Need Help !
 

also .. when i opened the specs page i put the link for before .. i didn't understand a word ! .. except maybe for the RPM/V which is think it's RPM per Volt .. so id appreciate it if you could explain it to me;)

RE: I Need Help !
 

I personally don't have the answers you're looking for, but you should be able to get some useful info here:

[link=http://www.rcgroups.com/vtols-360/]Linky[/link]

RE: I Need Help !
 

do a search on youtube for vtol,you should be able to pick up some pointers.

RE: I Need Help !
 

My opinion?
Your budget is small for what you want to do so:
Use brushed motors and ESCs and NiMH batteries, these will be more than enough for what you are trying to do and save some more of your budget for other things.
Yes Kv ratings on the electric motors are rpm per volt but only IF the motor has enough torque to acheive full rpm with the load you have on it.(sorry I can't help much with that)
If I remember correctly there are RC flying clubs in the Cairo area, you could probably get more help with someone there and you will need someone to pilot this aircraft as well.

RE: I Need Help !
 

rmp/v means just that, but don't get confused that more load the motor has on it the rpm drop i.e. a prop.

Higher rpm/v motor usually use gear reduction to achive higher torque. The motor is cheaper but yo have to pay for gears.

Gears however allow you better speed control especially at low rpms.

Ducted fan units however need as many rpm's as possible.

There are more exact sciences envolved here.

I think i know what you are trying to make here. i have seen something similar
[img][/img]

RE: I Need Help !
 

healthyboy....3 motor will be tricky to stablize since two will have to spin in the same direction. The motor that spin in the opposite direction will have to have 50% mor torque to counter the other two motor. THis is where a gyro comes in handy. it will automatically increase speed of thrird motor to counter other two motors. I am not sure if you can meet your budget of $500 with three motors, three esc's, a gyro, a receiver, a transmitter, battery, plus the material to build this, and props. It will be very tricky.

to try and stay in your budget you will have to go with less expensive electronics such as Mystery, or Turborix. These are fairly inexpensive but have known to fail on occassion. I have never had a problem with them.

Again not knowing exactly how many controls are needed determines the number of channels needed on the receiver and transmitter.

thrust is one channel, all three motors at the same time
maybe pitching each motor would be easier than trying to contol it's speed...I don't know
anyway forward and backward pitch is another channel
left and right pitch is yet another channel
spin in a circle as in a tail spin on a helicopter is another channel.

Well that's 4 channels right there.

Four channel transmitters and receivers are fairly cheap.
Above that they start getting into the hundreds.
Goodluck.

RE: I Need Help !
 

so if rpm/v meant as i thought .. how many volts can i apply to the motor without frying it or the esc ?

also i noticed in the motor requirements the it needs an esc with 25A .. so do i need an ESC with exactly 25A no more no less ?


also do the motor and the esc have to be of the same brand ? and which brands do you recommend ?

RE: I Need Help !
 

The motors have ratings on them. The typical voltage for small scale is about 11.1 volts. There are many batteries with this voltage. The other factor to take into consideration is mah. This is has much current the battery can push out. The higher the number the more current available, however the battey also gets physically bigger and heavier.

Motor and ESC do not have to be the same manufacturer. The ESC should exceed the motor full load current rating. ( motor with 19A FLA need 20A - 30A ESC )

Remember each brushless motor will need it's own esc.

Brand does not really matter if this is a school experiment. Go with the cheaper MYSTERY or RC SMART should be ok.

Again try your local hooby shop and grab some magazines. Some hobby shops carry back issues for really cheap.

RE: I Need Help !
 

Why would a professor assign a group of students who know nothing of rc flight to build a "VTOL"of all planes?? Think about that. Might as well ask some Political Science majors to build a Saxaphone.

RE: I Need Help !
 

actually our project supervisor recommended esky motors and ESCs today .. for they have high performance and durability ...

when i searched i found something really strange ...

one of esky motors is 3800kv and is 25.99$ : http://www.nitroplanes.com/ek5-0006.html

while another one which is 3900kv (also esky) is only 16.99$ : http://www.nitroplanes.com/ek5-0005.html

i also found this brand : http://www.nitroplanes.com/eliteseries.html

it has motors with different rpms but they all are at the same price !

how come ??? or what am i missing ?


you're right .. i did asked my mechanics prof. today .. and he said that it won't be stable unless we modify our blades design and triangle arm .. but we found that it would be simpler to use a square rather than a triangle

RE: I Need Help !
 

hey cyclic hardover ...


actually i didn't understand exactly what you're trying to say .. but our study actually involves propulsion and thrust calculations rather than rc electronics and controls .. he actaully did tell us to buy a template remote control and use it .. but the expermint is actually about the weight of our prototype and the lift force of the motors ...

RE: I Need Help !
 

Healthy,

What size model are you looking to get off the ground?
I am not sure that the current computer radio for R/C has the ability to control 3 or 4 motors ESC's in the manner that you want.
You will need to mix the ESC's for pitch and roll as well as be able to increase/decrease all throttles propotionately unless the model will be teathered, or secured in some manner to prevent adverse attitudes.
Does the model have to transition to conventional flight after takeoff, or just hover?

Bob

RE: I Need Help !
 

actually we thought about uztilizing the thrust components to make the model fly in a certain direction i.e. if we want it to move foreward then the rear motors should spin slightly faster than the foreward motors and so on for left and right and back ..

i don't know exactly how to have such control over motors .. i first thought that i'd have to control each motor's speed individually .. but RedGN said that if i use a gyro .. it can automatically change the motors speed in differential manner for example ...

RE: I Need Help !
 

You might want to ask this guy for assistance:

http://www.youtube.com/watch?v=fEWgby0ts5c

Bob

RE: I Need Help !
 

If your trying to achieve simple calculations, go buy some simple remote hover craft or something. Sounds to me this is what your looking to do more than a flyable aircraft. Save you a whole lot of time and effort

RE: I Need Help !
 

I used to do a lot of vertical take-offs and landings with these:

http://www.estesrockets.com/assets/i...ghtprofile.gif

Straight up. Straight down (unless a thermal catches it and then it's off to Nova Scotia and points East).

RE: I Need Help !
 

the whole idea is that we have to build it ourselves guys ...

so what about those motors i asked about .. what do you think ?