Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Electric equipment for airboat  (Read 2316 times)

greengin

  • Shipmate
  • *
  • Offline Offline
  • Posts: 7
  • Model Boat Mayhem is Great!
  • Location: Sutton UK
Electric equipment for airboat
« on: November 08, 2017, 10:27:04 am »

Hi,


This is my first post in this forum  :-) . I'm building an airboat
 from scratch, and I thought I'd ask for feedback about the electric equipment.
The airboat is around 45cm long, balsa wood, and I have the following:


- Brushless A2212 2200KV motor
- 6030 3 blade propeller
- 7.2V 22mAh battery
- 30A ESC
- SG90 servo


I bought all this before finding this forum, so mostly it was chosen by looking at equipment used in commercial kits.
Actually, I first bought a ESC suitable for helicopters... so it didn't have reverse  {:-{ . I'm now waiting for a new one.


Does the selection make sense?


Thank you!
Eloy
Logged

Big Ada

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,143
  • Location: Kent UK
Re: Electric equipment for airboat
« Reply #1 on: November 08, 2017, 05:24:42 pm »

I have built 3 Air Boats all from scratch and my own design, sorry I don't know a great deal about Brushless motors, I just used what I had to hand, and none of them have reverse, I am just careful where I steer them.
Mine are all built from Styrene sheet.
Have fun with them.
You can sail them most anywhere, even on puddles, just don't annoy anyone.
It would help if You would add your Location to your Profile, someone may live just around the corner from you and be pleased to help you out.

Len.
Logged

greengin

  • Shipmate
  • *
  • Offline Offline
  • Posts: 7
  • Model Boat Mayhem is Great!
  • Location: Sutton UK
Re: Electric equipment for airboat
« Reply #2 on: November 08, 2017, 06:10:01 pm »

Thanks for your answer :). I've just updated my profile to include location.


There was an additional problem with the ESC that I didn't mention. Perhaps because the throttle stick in my transmitter is designed for reverse (works the same way as the horizontal stick), after calibrating the ESC for it, if I turn off the transmitter the motor goes to full throttle. I'm not sure it's because the ESC and tx are not designed for each other, or just the ESC is faulty.


Can I ask, when you design your airboats, what's the max angle for the rudder?


Eloy
Logged

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,326
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Electric equipment for airboat
« Reply #3 on: November 08, 2017, 09:50:09 pm »


There was an additional problem with the ESC that I didn't mention. Perhaps because the throttle stick in my transmitter is designed for reverse (works the same way as the horizontal stick), after calibrating the ESC for it, if I turn off the transmitter the motor goes to full throttle. I'm not sure it's because the ESC and tx are not designed for each other, or just the ESC is faulty.


This is probably not a faulty ESC, just a "feature" that some ESCs exhibit - if they lose the commands from the transmitter, they can default to flat out.  The golden rule is to always switch the transmitter on first , then the receiver and when finished, switch off the receiver then the transmitter.  Switching off the receiver might mean disconnecting the battery if you don't have an on-off switch on your airboat.  And if your ESC is behaving erratically, keep your fingers well away from the propeller!!!  %%   Remember, Tx on first, Tx off last.  Repeat after me, Tx on first....  If I seem a bit insistent about this, it's because a fellow club member lost the tip of his finger in an airboat propeller because he forgot this rule.   :police:

Greg

jaymac

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,140
  • Location: Somerset
Re: Electric equipment for airboat
« Reply #4 on: November 08, 2017, 10:28:46 pm »

Logged

greengin

  • Shipmate
  • *
  • Offline Offline
  • Posts: 7
  • Model Boat Mayhem is Great!
  • Location: Sutton UK
Re: Electric equipment for airboat
« Reply #5 on: November 09, 2017, 05:05:19 pm »

This is probably not a faulty ESC, just a "feature" that some ESCs exhibit - if they lose the commands from the transmitter, they can default to flat out.  The golden rule is to always switch the transmitter on first , then the receiver and when finished, switch off the receiver then the transmitter.  Switching off the receiver might mean disconnecting the battery if you don't have an on-off switch on your airboat.  And if your ESC is behaving erratically, keep your fingers well away from the propeller!!!  %%   Remember, Tx on first, Tx off last.  Repeat after me, Tx on first....  If I seem a bit insistent about this, it's because a fellow club member lost the tip of his finger in an airboat propeller because he forgot this rule.   :police:

Greg


I got the second ESC, reverse is now working. Start is much smoother than with the other, there's is less jerk when starting the motor. It has the same "feature", if I turn off the tx the motor goes on half power. Not ideal :S. But at least if I turn the tx on again, control is regained and the motor stops. It also "seems" safe to turn on the rx first, but I won't try that with the finished boat. I will remember the steps, thanks for the suggestion :).


This second ESC has a small problem: if I switch direction abruptly, sometimes the motor brakes. The brake action seems very hard, I wonder whether it can damage the balsa wood structure that will support the motor.


I still haven't received the propeller. Scary to read what happened to your colleague! Was it because he was using a specially powerful motor, or higher voltage? Or could it also happen with the A2212 2200KV motor at 8V?


Eloy

Logged

Big Ada

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,143
  • Location: Kent UK
Re: Electric equipment for airboat
« Reply #6 on: November 09, 2017, 05:21:11 pm »

Thanks for your answer :). I've just updated my profile to include location.





Can I ask, when you design your airboats, what's the max angle for the rudder?


Eloy

45 Degree both ways.

Len.
Logged

JimG

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,268
  • Model Boat Mayhem is Great!
  • Location: Dundee
Re: Electric equipment for airboat
« Reply #7 on: November 09, 2017, 07:36:27 pm »


I got the second ESC, reverse is now working. Start is much smoother than with the other, there's is less jerk when starting the motor. It has the same "feature", if I turn off the tx the motor goes on half power. Not ideal :S. But at least if I turn the tx on again, control is regained and the motor stops. It also "seems" safe to turn on the rx first, but I won't try that with the finished boat. I will remember the steps, thanks for the suggestion :).

Are you using 2.4GHz radio? This behaviour could be due to the failsafe setting, often this is where the throttle was when you bound the receiver. Try rebinding with the throttle stick set to motor off.  Older 40MHz and 27MHz sets would not do this as they had no failsafe and the receiver stopped sending the signal to the esc when the radio signal was lost, this normally stopped power to the motor.

Quote


This second ESC has a small problem: if I switch direction abruptly, sometimes the motor brakes. The brake action seems very hard, I wonder whether it can damage the balsa wood structure that will support the motor.


I still haven't received the propeller. Scary to read what happened to your colleague! Was it because he was using a specially powerful motor, or higher voltage? Or could it also happen with the A2212 2200KV motor at 8V?


Eloy

Sounds like it could be a car esc, these often have a brake function when you first reverse. then when you center the throttle and reverse again the motor will reverse. Do you have programming instrructions for the esc? You may be able to remove the brake function and have only forward, stop and reverse.

With electric motors driving air propellers you must always be careful to keep fingers out of the propeller arc. While it may not go through bone it will remove a finger tip if not careful. As long as power is being applied the motor is trying to turn so can continue to cut as long as your flesh is present As long as the battery is connected keep clear of the propeller it is live. Even if the throttle stick is at neutral it only needs the transmitter to be dropped or knocked for the motor to start.

Jim
Logged
Dundee Model Boat club

greengin

  • Shipmate
  • *
  • Offline Offline
  • Posts: 7
  • Model Boat Mayhem is Great!
  • Location: Sutton UK
Re: Electric equipment for airboat
« Reply #8 on: November 09, 2017, 08:36:08 pm »

Are you using 2.4GHz radio? This behaviour could be due to the failsafe setting, often this is where the throttle was when you bound the receiver. Try rebinding with the throttle stick set to motor off.  Older 40MHz and 27MHz sets would not do this as they had no failsafe and the receiver stopped sending the signal to the esc when the radio signal was lost, this normally stopped power to the motor.


It is 2.4GHz, yes. Binding seems automatic, there's nothing in the intructions about it, only the programming mode. The programming options don't includle anything about failsafe power level either :(.


Sounds like it could be a car esc, these often have a brake function when you first reverse. then when you center the throttle and reverse again the motor will reverse. Do you have programming instrructions for the esc? You may be able to remove the brake function and have only forward, stop and reverse.

With electric motors driving air propellers you must always be careful to keep fingers out of the propeller arc. While it may not go through bone it will remove a finger tip if not careful. As long as power is being applied the motor is trying to turn so can continue to cut as long as your flesh is present As long as the battery is connected keep clear of the propeller it is live. Even if the throttle stick is at neutral it only needs the transmitter to be dropped or knocked for the motor to start.

Jim


No option for changing brake in the instuctions (k075B). It is advertised in eBay as suitable for boats, but I guess that doesn't mean much... That's not exactly the behaviour of my ESC: From forward, if I move the throttle (not suddenly) all the way down, the ESC simply removes motor power, without brake. To actually engage reverse, I need to leave the throttle in neutral for a second, then move it down.
I don't know anything about RC or electronics, but I find this a bit strange. I guess I should add that I'm buying components as cheap as I can find :S.


Anyway, with a bit of care the brake is not activated, so it may be ok.


About the propeller. I'll have to add a structure around the propeller for safety, as the goal behind building the airboat is to play with my 4 year old! (Plus I'm clumsy enough).
 
Logged
Pages: [1]   Go Up
 

Page created in 0.097 seconds with 21 queries.