RC seaplane landing sensor

Using Arduino Project Guidance
1

Hello,

I'd like to rig up an ultrasonic distance sensor mounted to my FPV RC seaplane that sends beeps down the audio channel of my video transmitter, and the beeps get closer together and higher in pitch as the distance off the water decreases during landing. Landing in glassy water is a challenge because the surface is nearly invisible.

1.) Regarding attaching the arduino to the transmitter... I don't have much experience with Arduino but is it as simple as just taking code for beeping a buzzer, but instead of connecting the buzzer I'd just connect it to the transmitter's audio & ground? What about impedance matching, is it important? Or as long as I get the audio levels within the appropriate range (1Vpp) will I be ok?

2.) Waterproofing. I plan to encase the sensor board itself in resin, except for the 2 "speaker" openings. Is it ok if those speakers get wet? If they shouldn't, would something like this material work for ultrasonic range? It is advertised as "sound transparent, weather resistant." http://www.daleproaudio.com/m-345-under-cover.aspx I imagine being totally waterproof would be impossible since air needs to move to create sound, and where air can get in, water could get in.

2

Yes, you can get waterproof ultrasonic detectors but they are not cheap, even though they are used in millions of car bumpers as reversing sensors! I know this because I wanted to buy some but baulked at the price.

I would say that you could first test out your theory with a standard HC-SR04 cheapie set (and watch my YouTube video #17 about all this) and if it all works then consider buying the waterproof ones.

URL in the footer of this post.

Edit: no you can't get the standard HC-SR04 ones wet (long term) and expect them so survive but as an initial proof-of-concept I'm sure they will survive a landing or two. But you could prove the principle by landing on a smooth runway or pavement.

3

Micro-switch with a long tail mounted on underside of fuselage,, connected to a LED and avail power. place LED in peripheral view of camera. wire switch to light led when pressure on tail closes switch contacts.