Airspeed sensor ... should it read zero with zero air movement?

[SnoozeDoggyDog]

Hi
    I've finally got round to fitting a pitot to my vector. It's reading 30 on the OSD. There is zero air movement in my garage. It continues to read 30 with my hand over the the full tube. If I blow on the front of the tube the numeric rises.

I'm familiar with how to offset the number in the config screen of the vector software. Do i simply need to get the number down to zero?

Thanks
P

[FPVSteve]

Unfamiliar with the Vector, but on the Tornado OSD there is an option in the menus for "Reset Airspeed" which puts it to 0.

[SnoozeDoggyDog]

Cheers Steve. I just needed a confidence check. I thought it would be zero but did wonder if it was some sort of quirk with airspeed or if the airspeed needed to be set to the average stall speed. If that makes sense.

Thanks
P

[BlueFlyer]

What else do you think it would read at zero airspeed.... 14.5?

You're off your head lol

Also, you need to be very careful with the settings of your vector now you've got 2 components telling it it's speed.

As you say in your opening comment, the OSD is showing 30. This is dangerous as the vector is being told the plane is still moving... that means the safety throttle hold (that activates when the aircraft is no longer moving) won't actually be engaged and if you knock your throttle, or turn off your radio by accident, RTH WILL kick in and the motor/prop will spin.

This happened to me at the field after a flight.
I had been so used to the safety throttle hold auto engaging that I got complacent. This was one of my early flights with the airspeed sensor on the vector, I landed and had a brain fart... turned off my tx before unplugging the LiPo.

Normally nothing would have happened as it would have registered a speed of zero and the throttle safety would have saved my bacon.... However the airspeed sensor was still registering an airspeed and so the Skyhunter's RTH kicked in and it throttled up. As it was on the ground, the prop just shattered and the plane lurched forward. I was lucky that it went into my leg and I was able to quickly yank the LiPo connector off.

I learnt some valuable lessons that day

1. I need to concentrate on safety first, once landed, 1st thing to do is disconnect main LiPo.

2. I don't fly in ridiculously high winds, therefore having just GPS speed as an indicator is fine for me (personal preference) and therefore I don't need/want an airspeed sensor

[SnoozeDoggyDog]

Yeh I'm with you. If the plane is on the ground air is still being blown through the pitot. Therefore the vector thinks it's moving and will engage RTH if the control link is lost.

Thanks
P

[BigT]

Yep the mfd does that too. Also it may be best to let the unit warm up for a couple of minutes before doing the reset.

[BlueFlyer]

You know what... It's my opinion that these hobby grade airspeed sensors are so inaccurate, and to get even close to a modicum of useful accuracy you need to do far too much "work".... Unless you're flying in stupid conditions, there's no need for an airspeed sensor.

If your AP of choice has one as standard, and it uses JUST that reading to control the throttle in RTH... then I guess you're stuck with having to use it.

Personally, I don't remember people having half as many "issues" way back when there were no APs, no airspeed sensors... people learned how to fly planes, then they put cameras on them, because it was fun. Then OSDs turned up, and it helped people out a bit (voltage, home arrow). Now we're so dependant on APs to do everything...

From stabilise the plane (giving a false sense of competency in piloting an RC plane), to bringing the damn thing home when something goes wrong.... why would you want it to come home??? because now you've got an expensive autopilot inside, there's a lot of money flying away there if it doesn't RTH.

Storm OSD.

One of the most reliable OSDs/APs in the history of FPV... basic, GPS, gyro and accelerometer based flight controller. Simple RTH, throttle on failsafe (just make sure you set it high enough). It's just a shame that they're almost impossible to find anymore, and I don't even know if the RCGroups "support" thread is still going, or if any firmware updates are being made.

Point is... this is a death spiral of a hobby... once you're in, you just get caught up in the next best thing, the so called "progression", long range flying, trackers, fancy pants ground stations... where will it end?? Why make things difficult for yourself!!??!?!


Oh, hold on... what's this guy saying? This guy has all the fancy gear... tracker, modern APs, fancy ground stations... what a hypocrite. No... it's simply speaking from experience. I wish I could just turn up to the field and fly a damn plane and see what it sees in the goggles... without needing a frigging degree in electrical engineering, or having to remember to do a 20 point checklist BY MEMORY on all my kit. And what's it all for? It was supposed to be for fun, to make me relaxed and happy, but with very limited opportunities to get out flying, it's a real downer to work one's self up to a "flying session" only to be so stressed out about it, that it's not fun anymore.

So what's the point in this rant? (sorry for the rant)

If something is causing you worries, and that something isn't 100% vital to enabling you to have fun in this hobby... forget about it. Do you need an airspeed sensor? Or is it just introducing something else you're going to have to worry about pre/during/post flight?

I think I've convinced myself to sell up and draw down lol

[FPVSteve]

I agree with you 100% ... although most of the time the problems people have really do boil down to one thing: not having the plane set up 100% in MANUAL before they even think about engaging the autopilot.

[SnoozeDoggyDog]

I wasn't worrying about about my airspeed, it was just something to play with and to gain a better understanding. And in some respects you have no idea what conditions are like at 300ft compared to on the ground. So you might think you're flying in 6mps on the ground but things can be very different 300ft up.

P

[Dizzy]

So diving in the middle of a downdraught at the same relative speed as the airflow in the same direction in theory could give you a heads up display showing zero air speed but a GPS vertical speed . Be awesome to see that happen  :D

dizzy😆 the devil's advocate lol

[elmattbo]

Totally agree blue. When I got into this hobby I was making it complicated, but because I was always short on time at the field I realised I needed all my kit in a rucksack, goggles on, switch on and go. I also don't see the point in being too automated as it makes it all a bit dull for me. Admittedly I have no interest in longer range (so I just stick to 5.8 video, thank god!) as I quite like flying into trees(!) or thermalling overhead so that may affect my judgement.



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[Loopdreams]

Yeah goggles, plane, TX for me.  Stuff sitting in a field surrounded by wires and antennas and looking like a cross between a lost angler and a TV OBU.

[FPVSteve]

I take a groundstation (built into a case) just to record the downlink but it has its own Rx ... I fly from my goggles with their inbuilt rx.