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HK Anemometer

fliteadmin

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#1

In this episode of Flite Test Josh and Josh show us a great new tool from Hobbyking. It's called an anamom... an annymo... uuhhh. Just watch the episode. Josh and Josh will tell you what it is.



 

JimCR120

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#5
I don't have an anemometer. But I do have my big fat face that can feel the wind. It's not a bad indicator either but sometimes I get interference from my very think skull which doesn't always process the information correctly. Even when my son was speaking sensibly, "Dad, I think it's too windy." Nope, didn't process. Result=my scratchbuilt plane might be in this county or perhaps Canada. It was a windy day.
 
#10
Could you put this on a Electric RC Car to see how fast it is going?
theoretically you probably could, If your in a controlled environment. Like zero wind conditions. If you have like a car GPS it records maximum speed, so if you put that on your RC car you could at least get a max speed.well it all matters how big your RC car is, if it could fit a GPS in it. Just a idea
 

StoneKap

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#12
There has been quite the disagreement regarding airspeed vs. groundspeed. Many believe that groundspeed doesn't affect the airframe. I disagree...

Most don't take in account inertia. While ground speed does not affect lift it does however affect what the airframe and power system have to deal with. Hypothetical: If your plane requires 30mph to maintain lift and you are flying 30mph into a 30mph wind your ground speed is 0mph and your plane is not dropping. Turn with the wind. Now your airframe must reach a ground speed of 60mph (an additional 30mph) to maintain lift. If you were sitting in the plane you would feel this.

Thoughts?
 

JimCR120

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#13
I disagree on a couple points.

You wouldn't feel anything but the changes of acceleration/direction. Once you are straight and level again the 30 mph indicated airspeed (IAS) should feel the same regardless of what the earth below is doing. That is, of course, as long as the earth remains below. Once there is contact made, ground speed (GS) matters plenty to us and the airframe.

In physics, acceleration is the change in velocity over time. This is what you are feeling because of inertia. However once the new velocity is achieved, acceleration is 0.

How about this modification to your hypothetical: You are in that same 30 mph headwind doing 0 mph ground speed (virtually hovering) but then the head wind gradually dies down to 0 (acceleration). Soon your IAS and GS both read 30 mph. With no acceleration there is no change of inertia to feel.

Here's one that we experience. Some places (like airports) have moving walkways. If you're running late you can run from one to the next but every time you step on or off there is that positive or negative acceleration that you do feel but only for a moment. It's that acceleration of our own bodies that is felt.
 
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JimCR120

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#15
Ok André, I guess I should concede and agree at this point... which kinda puts this assertion of your into question.

Anyway, I have a thing about looking for the truth. I don't claim to always have it but I do like good discussion in the pursuit of it. And stuff having to do with science is just cool.

I suppose if I had a thumbs up/down button I could have expressed myself through those means and just left it at that. But we ain't there yet.
 

earthsciteach

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#18
Chad - (resurrecting an old thread here, but the debate still rages on) Bottom line is, you guys were correct in your suppositions and observations of an anemometer mounted on an airplane. I've been unsuccessfully arguing this point over on wattflyer. I keep telling myself to just drop it, but I can't seem to. I'm about to break out the diagrams and equations! ( I have already drawn them up).

There seems to be an alternate issue at heart, that you guys weren't even intending to address, and that is the "myth of the downwind turn." The controversy seems to be centered around this "myth." The confusion of this issue comes from the frame of reference that one is using. In fact, using anything other than a frame of reference outside of the airplane (even if it is two African swallows, which are non-migratory, carrying a coconut on a string-that's a reference^2) is necessary to understand the heart of the issue. And, again it is an issue that you guys didn't even bring up.

You intended to compare ground speed vs indicated airspeed. Y'all kinda did a poor job of summarizing that (its a teacher thing) at the end of your video. I doubt anyone would argue that there is a difference between indicated airspeed (airplane frame of reference) and ground speed (ground frame of reference) as long as there is wind. Folks have run with that and are saying that the airplane doesn't care about its groundspeed (true) and only cares about its IAS (true). But, they fail to understand that, as you said, aircraft have inertia and don't instantaneously assume the speed of the wind. Ok, our rc planes do. But real planes don't, due to inertia. If you are flying into the wind then kick hard rudder, your ground speed increases, but IAS decreases as you turn downwind.

Back to the "myth." If you are in an aircraft that has sufficient inertia (real one) and are flying REALLY close to stall (within the ground measured wind speed), then you likely will spin in to your death if you turn downwind without increasing throttle. Simple mechanical physics.
 

JimCR120

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#19
I like your comprehensive explanation. I think you explain it very well and I would wonder how anyone would have grounds to dispute this.