Multirotor Emergency Parachute?

[andybenton]

well, we need to remember that the props spinning will act like a brake in and of themselves...

remember when a prop or rotor spins, it acts like a disk?

as for wind drift, it is true that it does take a few hundred feet for them to effectively slow something to a crawl, however I think that any amount of slowing would be better than none, in reality, if this device could save the components on board, at least enough of them that the device would have paid for itself, then its at least began to do its job.

pyrotechnics are truly light, easy, and reliable, however im not entirely sure of everyone having access to them, or being able to use them in a safe manor. (im not protectionist, but I do believe that pyrotechnics and electronics should be played with separately)

the idea of having the parachute open on its own under those rods is brilliant! there may really be something to that, and a quad built with a pvc frame... you could just stuff it into the boom end,....

imagine passing a rubberband over the opening on the end of the boom, and affixing it each side, then collapsing the chute, and inserting it into the boom so it would be under pressure from the rubber band... it would be as simple as a 5 gram servo on the end of the boom to release something like a small metal rod.. (think ft glider tow element) to let the rubberband propel the chute out of the end of the boom....

someone want to weigh there quad with battery and fpv equipment on board??? ive got some pvc, a 5 gram servo, and some lead shot... Ill weigh my sensors and arduino and make an analog (minus props) and start chucking it out some windows LMAO

 

[rockets4kids]

Great information. But the reason for this thread is for when the bovine excrement impacts the aero propoltion device. So its not going to be planned or expected, motor breaking will be the last thing on your mind.

My point was that if you are going to use a system that does automated deployment, you are going to want to add some intelligence, because deploying a parachute on any failure is as likely to make things worse as it is to make them better.

I have a fair bit of experience with pyrotechnic deployment, and I can say that implementation on a quad really wouldn't be all that difficult, expensive, or pose much of a weight penalty. However, the only time I think it would really be of any help is when flying above 300 feet over wide open spaces.

 

[andybenton]

I have a fair bit of experience with pyrotechnic deployment, and I can say that implementation on a quad really wouldn't be all that difficult, expensive, or pose much of a weight penalty. However, the only time I think it would really be of any help is when flying above 300 feet over wide open spaces.

True... very true. but again, no system will work for every case.
In the military there is no one gun for every mission, no one tank for every mission, no one heli for every mission...
In civilian live, no one car fits ever need, no one house is perfect for everyone, television, computer, phone, ect.

its complex and implementation of the system would depend wildly on the purpose of the craft....

however, with some creativity, we may be able to make the two ideas (air bags, and chutes) modular and easily swappable (flitetest pun def. intended). if we were able to make them swappable then we would have something really going here guys.

 

[rockets4kids]

True... very true. but again, no system will work for every case.

And this is exactly why you would not want a parachute system to auto-deploy in the event of failure.

 

[chaos23]

This is why I like the bag idea. The size of the bags would be enough to manage the terminal velocity at hight and absorb enough to save at least 80% motors, booms and props can be sacrificial its the expensive gear I would want saved. And an ejection system is just over complicating things. At the most a drope chute can help with the TV at higher altitudes, but again some prior planning as with any pro setup rotor flite would determine the type or types of safety system needed for the job at hand.

 

[rcspaceflight]

Just to quickly add to what I said earlier about shutting off the motors, I think it might be a good idea to have the system just unplug the battery. My main concern is a lock out causing the MR to spin out of control and possibly accelerate straight towards the ground. The props would still spin freely to produce some drag. But air goes to the least resistance so I'm sure any falling MR will tilt to it's side so the props won't be able to produce any drag.

Although I admit that having a system that can unplug that battery is a huge risk. If the system does something weird, you can end up with a MR that's dead in the air and the chute/bags don't deploy.

I really like the air bag idea. If the airbags just stay out of the way of the props, it doesn't matter if they're powered or not. The airbags would still produce some drag to slow the MR down. And the MR doesn't have to land super slow/soft because the bags would absorb most of the impact.

andybenton is right about the PVC booms that hold the chute/bags. I'm thinking that the system wouldn't be something that can be added to any frame, but rather something build into a frame. It would make it the lightest possible that way.

 

[chaos23]

I wouldn't have a battery disconnect system. Plenty of MR control boards have systems to shut of esc power at lose of control. And most MR ESC will activate breaks to prevent motor and esc burnouts in the event of a problem. Plus the bags needed would not care if the props where going or not, they would stop them dead or snap them off draining all harmful kinetic ensrgy before killing a puppy.