HurricaneZachary
New Member
I am currently working on a weather-resistant multirotor for a university engineering project (has to be able to fly in heavy wind, any amount of rain), and I thought I'd share a quick summary of my findings! A lot of this has been researching what people do to protect their multirotors from water, so the information below is a combination of discussion on other forums and my own research. In terms of wind protection, we settled on a Y6 frame for its purported wind resistance (low cross-sectional area, higher lift and more redundancy compared to a quadcopter), and are trusting the Pixhawk flight controller to do the stabilization.
In general, industry uses shells to enclose the multirotor and protect its electronics from water. These are usually injection moulded, which is prohibitively expensive for hobbyists. Vacuum forming is also used, but it's harder to get tight tolerances with vacuum forming.
Hobbyists usually add aftermarket stuff to their multirotor. CorrosionX is a corrosion-prevention spray that has an oily finish. According to a distributor, it needs to be reapplied every 6-12 months, depending on exposure. Conformal coating is a spray that forms a thin shell over a PCB; according to a distributor, it very rarely, if ever, needs to be reapplied (told me it was good for "twenty years", though if the surface of the PCB is being scratched, I would reapply as needed).
This is a good video from FliteTest about water protection:
In general, CorrosionX can be used for servos, radio receivers and battery leads.
ESCs: The link above recommends epoxy-ing the open ends of a heat-shrinked ESC. I found that conformal coating will also protect your ESCs (I ran some underwater for about a minute), and it is designed for circuit boards, so heat dissipation is not a problem.
Motors: brushless DC motors have insulated leads, so they don't need to be protected from freshwater (rain). If they come into contact with dirt or saltwater, rinse them off.
Barometer: protecting the barometer from water is one of the stumbling blocks for making a multirotor watertight, since it needs to be able to read air pressure. A waterproof, breathable fabric like Gore-Tex repels water, but lets water vapour (ie air) through, and it is easy to make a fabric pressure equalization vent for a multirotor with an existing shell. Cut a small hole (nickel sized? quarter sized?) in the side of the shell, and stretch some fabric over the hole, then fasten it (tape, hot glue). Some people build U-shaped tubes to let air in, but keep pressure out. However, I heard that if you move too fast in a certain direction, you can ram air through the tube and increase the pressure for the flight controller, and I think the Gore-Tex avoids that problem.
In short, covering your electronics with a shell is the best way to protect them from water. This QuadH20 build guide can help protect holes where wires come out of the shell: http://www.quadh2o.com/resources/the-quadh2o-build-guide/. Otherwise, a combination of CorrosionX and conformal coating can protect most components.
I still have some questions I wasn't able to resolve, namely:
- What kind of protection do connectors (XT-60, bullet, pins on Pixhawk) need? Will covering them with something (CorrosionX, dielectric grease) prevent good electrical contact?
- Will a barometer (such as on the Pixhawk) be destroyed by water? I have heard that it stops working if it's covered (with conformal coating or CorrosionX), but I don't know if it can get wet (ie, if I could protect the flight controller by coating everything but the barometer opening).
In general, industry uses shells to enclose the multirotor and protect its electronics from water. These are usually injection moulded, which is prohibitively expensive for hobbyists. Vacuum forming is also used, but it's harder to get tight tolerances with vacuum forming.
Hobbyists usually add aftermarket stuff to their multirotor. CorrosionX is a corrosion-prevention spray that has an oily finish. According to a distributor, it needs to be reapplied every 6-12 months, depending on exposure. Conformal coating is a spray that forms a thin shell over a PCB; according to a distributor, it very rarely, if ever, needs to be reapplied (told me it was good for "twenty years", though if the surface of the PCB is being scratched, I would reapply as needed).
This is a good video from FliteTest about water protection:
ESCs: The link above recommends epoxy-ing the open ends of a heat-shrinked ESC. I found that conformal coating will also protect your ESCs (I ran some underwater for about a minute), and it is designed for circuit boards, so heat dissipation is not a problem.
Motors: brushless DC motors have insulated leads, so they don't need to be protected from freshwater (rain). If they come into contact with dirt or saltwater, rinse them off.
Barometer: protecting the barometer from water is one of the stumbling blocks for making a multirotor watertight, since it needs to be able to read air pressure. A waterproof, breathable fabric like Gore-Tex repels water, but lets water vapour (ie air) through, and it is easy to make a fabric pressure equalization vent for a multirotor with an existing shell. Cut a small hole (nickel sized? quarter sized?) in the side of the shell, and stretch some fabric over the hole, then fasten it (tape, hot glue). Some people build U-shaped tubes to let air in, but keep pressure out. However, I heard that if you move too fast in a certain direction, you can ram air through the tube and increase the pressure for the flight controller, and I think the Gore-Tex avoids that problem.
In short, covering your electronics with a shell is the best way to protect them from water. This QuadH20 build guide can help protect holes where wires come out of the shell: http://www.quadh2o.com/resources/the-quadh2o-build-guide/. Otherwise, a combination of CorrosionX and conformal coating can protect most components.
I still have some questions I wasn't able to resolve, namely:
- What kind of protection do connectors (XT-60, bullet, pins on Pixhawk) need? Will covering them with something (CorrosionX, dielectric grease) prevent good electrical contact?
- Will a barometer (such as on the Pixhawk) be destroyed by water? I have heard that it stops working if it's covered (with conformal coating or CorrosionX), but I don't know if it can get wet (ie, if I could protect the flight controller by coating everything but the barometer opening).
