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Zoom › idea for making ZOOM better in windy conditions!!
05-31-2004 04:28 PM  13 years agoPost 1
mattijs

rrApprentice

Keerbergen Belgium

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I don't have a zoom but seeing my hornet sometimes has a hard time with winds i gather the zoom, altough probably less, also goes up when it is hit by a gust of wind.

The zoom has a seperate collective servo, wouldn't it be a great idea to use a holding hold gyro mounted on it's side to make the heli stable on the collective. Maybe even a normal damping gyro could work. If you have a zoom and a spare gyro...please try it. It's easy to set up and if you start on almost no gain and work your way up it shouldn't really shouldn't be all that dangerous (i can imagine too much gain makes a really nasty jumping heli)

If somebody is able to try it on his zoom and it works (good) i am going to make a mixer (probably with a pic controller) and do it on the hornet .

I have been dying to make a good electirc circuit for my heli but wasting a µcontroller for some lights to blink just isn't worth it. Now i can make the mixer and a light controller in one. I figure i might also have to use a seperate collective channel and use a flat collective curve in the ccpm menu. Decoding the collective out of three channels too put the signal in the gyro might prove to much hassle but that is ofcourse something you ZOOM guys won't have to worry about.

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05-31-2004 04:40 PM  13 years agoPost 2
vitek

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Corvallis, OR

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The zoom has a seperate collective servo, wouldn't it be a great idea to use a holding hold gyro mounted on it's side to make the heli stable on the collective. Maybe even a normal damping gyro could work. If you have a zoom and a spare gyro...please try it.
I'm pretty sure that this wouldn't work. Gyros measure and respond to angular acceleration, not linear. Being so, I would expect you could put a gyro on the cyclics and rudder [they make the helicopter rotate along the given axis], but not on the collective.

To see this for yourself, set your helicopter on the floor. Turn on the TX and the RX. Place the landing skid against a guide, such as a wall. Now slide it back and forth. You will not see much response at the output servo. Now rotate the helicopter, with the gyro at the center of rotation, and again with the gyro not at the center of rotation. The output servo will show quite a bit of deflection when it is rotated, regardless of whether or not the sensor is on the axis of rotation...

One thing you can do is to reduce the overall collective range when flying in windy conditions. Doing so won't give you a killer climb out, but will make the collective stick a little less sensitive, which will help make it easier to stop the bobbing.

Travis

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05-31-2004 05:58 PM  13 years agoPost 3
mattijs

rrApprentice

Keerbergen Belgium

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so putting a gyro under the mainmast will make it work?

I thought it was sensitive to lineair motion put it responded to rotation because of it being out of the center. Thinking about that for a second makes me see that aileron would also be seen as rotation so it looks you are right.

It is always posible to translate collective to rotation if you take the gyro and put it sideways on a tilting tray, held verticel by two springs on the top and bottom of the tray and a silicon tube in the center. It's a bit tricky but it's just something i came up with just now, there might be a better way...

Maybe i can find a good linear motion sensor and make the device myself. I am sure that once you see your own built sensor + controller move a servo it's so motivating that carrying on and really make it work won't be a chore but a delight.

Another thing, do normal gyro's figure out rotation by subtracting the liniear motion from two linear motion sensors. I can see that the sensor that's closer to the mainmast will have less than the one furthest away and the two signals subtracted give a good way to estimate rotation

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05-31-2004 10:45 PM  13 years agoPost 4
vitek

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Corvallis, OR

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so putting a gyro under the mainmast will make it work?
No. It will not work. You will need a linear motion sensor. As I said before, our gyros are angular motion sensors. The gyro units used today are specially designed so that they don't respond to linear acceleration.

Think of it this way. Which orientation would you mount the gyro so that it would respond to collective inputs?

Travis

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05-31-2004 11:17 PM  13 years agoPost 5
Twobeers

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Toronto, Canada

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Isn't this to some extent what the FMA Copilot does? Although I have seen a couple of other people besides Mike spend countless hours flipping there heli this way and that trying to re-initialize the thing to level off the heli properly. They have all given up and realized that right at the beginning it seemed like the next best thing to sliced bread it actually hindered their learning curve. Want it more stable in the wind, crank up the head speed. But try it on a more calm day first to feel out how much more lively the heli will be.

I lost my infamous tag line.

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06-01-2004 02:01 AM  13 years agoPost 6
vitek

rrKey Veteran

Corvallis, OR

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Isn't this to some extent what the FMA Copilot does
Not really. The Co-Pilot tries to level the aircraft by sensing the horizon. It does nothing to prevent ascending/descending.
Another thing, do normal gyro's figure out rotation by subtracting the liniear motion from two linear motion sensors.
Have a look at the gyros described at Silicon Sensing. I believe the datasheets give a little description as to how their gyros work. I believe their components are used in the 401/502/601 series gyros.

Travis

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06-01-2004 08:31 AM  13 years agoPost 7
mattijs

rrApprentice

Keerbergen Belgium

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Thanks for the link VITEK, very informative reading, i didn't know futuba bought all that. They aren't really to be credited for the GY line of gyro's as i don't really think it's hard to built a good gyro once you have these sensors.

Do you know any good accelerometers that could be used ? Over at the sensor site you gave me there was a gyro that also had two axis accelerometers but i specifcly need only one axis and no gyro so.

I know analog devices has them but the site isn't playing easy and doesn't want to give the pdf for the ADXL50 and or for its encestors.

Maybe i should try and get a hold of some samples, than again most samples I order never make it to my house ???

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06-01-2004 09:09 AM  13 years agoPost 8
mattijs

rrApprentice

Keerbergen Belgium

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I ordered two samples from analog.

The sensor is the adxl 202

Here is the datasheet for all you electronic nuts.

http://www.analog.com/UploadedFiles/Data_Sheets/70885338ADXL202_10_b.pdf


Does anybody have an assembly code of a standard elevon mixer or does anybody know a page on the web where the output signal from an RX is explained. I haven't got an oscilloscope at home so it might be necessary for me to know exaclty what signals to anticipate for.

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06-01-2004 09:12 AM  13 years agoPost 9
mattijs

rrApprentice

Keerbergen Belgium

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my current plan is to use on of the above sensors for up and down detection. If that works it will be impossible to make the heli go up even when you are moving and bank up by for example going forward and using the elevator to go higher. The collective will want to adjust and tilting backwards will not result in going higher but will flare the heli.
If that proofs difficult to fly i will have to use two more sensors to be able to know when you are going straight up or when your up going motion is due to pitching up or banking up (ail and elev)

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