Payload makes Spark Spin! Help?

[STEMDrones]

I velcro-ed a payload release to the spark - not much weight, and the spark has no problem flying at the start.

But then it starts to rotate (yaw) , faster and faster. I can counter it somewhat with the RC yaw at the start. And it's responsive to up/down and land. Once it's spinning to quickly, the RC yaw can't stop it.

Without the payload, the Spark does fine.

Help? I've tried calibrating the compass and IMU and that didn't solve it. Tried a second Spark, and that didn't solve it either.

Thanks!

 

[Spark 317]

Hello from the Hoosier Heartland, STEMDrones.

The Spark is small and wasn't designed for cargo.

I would suggest a Phantom series drone as they are robust and can handle a small payload.

You may be getting interference from the device and causing the problem or the Spark isn't stable in flight due to the imbalance of the device.

Here is a thread to look at, Dropping stuff...

There's some information worth pondering.

Welcome to the Forum.

 

[STEMDrones]

We're using it to teach physics in school gyms and auditoriums.

I love the Spark because of the size and I can get a full propeller cage for safety. I considered the Phantom and Mavic but spark just seemed like the best balance for size, noise, safety, and capabilities. If it stopped spinning, it'd be perfect.

 

[Spark 317]

We're using it to teach physics in school gyms and auditoriums.

Sounds like you have your first physics problem. ?

Since flying indoors, you won't have the GPS for stability and the Spark will use the VPS to help maintain position.

Are the sensors and /or the camera blocked on the bottom by the device?

 

[STEMDrones]

Sounds like you have your first physics problem. ?

Since flying indoors, you won't have the GPS for stability and the Spark will use the VPS to help maintain position.

Are the sensors and /or the camera blocked on the bottom by the device?

We tucked it far enough back on the battery that the downward IR transmitter&receiver have a clear shot of the ground for a fairly good angle, and it's nowhere near the camera. So I think the answer is no, although if the IR emitter casts a wide flood, perhaps some could be reflecting off the payload? But should that make it spin? Doesn't feel like it should, but that's why I'm posting here. I'm sure I'm missing something, and there's lots of experience in this forum.

I was afraid since I sat the payload further back (to avoid blocking the IR sensors) it would throw off the CG, but that doesn't seem to tip it or otherwise affect it, except for the spin, which wouldn't be CG-based.

Other theory - since it's held on by (strong) Velcro, there's a TINY bit of freedom for the mechanism to slide around. Could that momentum-lag be confusing the gyroscope? Does everything have to be totally rigid? Again, doesn't feel like the likely culprit.

 

[Spark 317]

Other theory - since it's held on by (strong) Velcro, there's a TINY bit of freedom for the mechanism to slide around. Could that momentum-lag be confusing the gyroscope? Does everything have to be totally rigid? Again, doesn't feel like the likely culprit.

I don't know.

I use this type of fastener on my Spark for the strobe lights, 3M Dual Lock.

Solid connection. But the strobes don't weigh much at all.

 

[STEMDrones]

Cool side note, a student asked if it could balance a playing card on top. The full propeller cage covers everything with a flat surface on top, so the card could sit above the central body easily. It worked great. So we put the entire deck of cards, without the box, on top, and it's still balanced perfectly. 52 pickup only happened the moment the spark landed in my hand. The moral of the story is that the spark both has a good payload capacity, and better balance than I do.

 

[hiflyer]

the prop protectors can cause problems also.

 

[STEMDrones]

the prop protectors can cause problems also.

For sure. Makes it much louder. But it flies quite well with the prop guard and no payload, and I'd rather not expose the props for this if possible.

 

[hiflyer]

I've had them interfere with the forward avoidance sensor. That doesn't seem to be a typical problem though. Since the problem is the same with two different Sparks that rules out the obvious..a weak motor. Did you try a different controller also? How do you land it while it's spinning?...

 

[twickers14]

I am so old I can’t remember if I did physics at school but think I did. This ain’t going to be scientific but as said above the Spark is so small (although amazingly stable) are you sure the payload was exactly positioned to be perfectly balanced in flight. The dynamics of the movement as Spark flies will surely affect its stability as it copes with speed, yaw, wind conditions etc. Probably far too simple but could the class not come up with a perfect location for the payload? OR how about suspending the payload somehow so that you might get a gyroscopic counterbalance thing going. Just some thoughts and have fun with the scholars trying to sort this challenge.

 

[aym924]

Could you try a series of dummy payloads of increasing mass until you reach that of the payload release. Sounds like a good physics experiment. I suspect sensor interference. Mass imbalance would surely impact tilt more than yaw?

 

[Mark Waco]

If your using a pack/ deck of cards you will make the back of the spark try to compensate for tail swing with added force and unbalanced payload. Think of it as if payload to scale was placed in a aircraft. Another thought comes to mind, tractor not trailer jacknife. The pulling unit looses traction and the payload continues to push in the failing correction.
This thinking followes through with your discription of payload placements.
Good luck.
I practice picking up the kids toy rings and place them in a bucket. When I had the hook rear of center I had pitch and yaw problems.

 

[I B Spectre]

Other theory - since it's held on by (strong) Velcro, there's a TINY bit of freedom for the mechanism to slide around. Could that momentum-lag be confusing the gyroscope? Does everything have to be totally rigid? Again, doesn't feel like the likely culprit.

I'm inclined to think this is contributing to the problem. Consider the Spark is optimized to lift itself and maybe a couple of extremely light accessories (prop guards, etc.). Aftermarket accessories such as a lens hood are very light and within the Spark's ability to compensate for whatever minuscule change in CG it might cause. You already have the added weight of full cage prop guards which at least provide a balanced distribution of the added mass. If whatever payload you add is not fully stabilized at least as much as the deck of cards, I surmise it could add to divergent oscillation. But them I'm not an engineer or a physics guy.

Also, if the gymnasium floor is reflective enough, the optical flow sensor might be unable to sense an image sufficiently to help similar to hovering over water.

 

[ajkm]

How do you know that the payload doesn’t affect the CG? I haven’t seen a CG envelope diagram with moment data provided, so a CG calculation can’t be done.

 

[JoeDimwit]

How far did you move the center of gravity?

 

[GeoM1]

Hello from the Hoosier Heartland, STEMDrones.

The Spark is small and wasn't designed for cargo.

I would suggest a Phantom series drone as they are robust and can handle a payload.

You may be getting interference from the device and causing the problem or the Spark isn't stable in flight due to the imbalance of the device.

Here is a thread to look at, Dropping stuff...

There's some information worth pondering.

Welcome to the Forum.

“Small” is relative, so if Phantom carries a load, Spark carries a smaller one. So the question to Joe’ is, how many grams/Oz is your load? And yes, is it composed of ‘radio’ materials?

 

[Northwood Mediaworks]

The shiny floor may have some play in this, and if the payload not rigid... those are my thoughts. If you do place anything on top, dont expect GPS to work outdoors reliably (I know you are doing this indoors, but just in case)