I have been working recently with the Robotics Association at Embry-Riddle Aeronautical University to provide the multi-rotor component of their 2013 Roboboat competition.
You can see some footage of the flight and collision testing above.
As the competition approached it became apparent the need for prop guards. Here are the two versions I came up with. The first was four Kydex rings with spokes that attached to the motor mounts
The second approach removed much of the excess material and reinforced the structure with 1/8" srung carbon fiber spars to increase rigidity and keep the weight low. There was a 10% drop in flight time and the throttle response seems relatively normal. ounts. I flexed the rings into an arc to provide rigidity yet maintain a perimeter around the prop. Worked well in minor collision testing, although the impact on flight characteristics and longevity where severely diminished.
I have seen a lot of approaches out there and would be interested in the feedback on these designs and what should be considered with regard to maintaining prop efficiency,reducing weight while providing suitable protection.
Comments
let me clarify. I don't attend ER and am not affiliated with the robotics association except as a sponsor. As the owner of AeroTestra I provided two HUGO sUAVs for a part of a robotics competition. The prop guards were designed as one off prototypes for compliance with competition regulations. I have described to my wife how enjoyable it is to get to participate. I hope as a focus turns to multi rotor sUAV applications, I can provide similar support (either full or partial) to those doing the research.
Or... perhaps a CF prop adapter in the shape of a ring that allows you to use any prop you have?
Remember, you heard it here first. ;)
I grew up in Florida, almost ready to attend E.R. but the aviation industry slump (in the 1970's) after Vietman sorta took that out of my life plan. I am glad you can attend and see a new opportunity in what I refer to as the 'micro aviation' industry.
-=Doug
Ok, I will admit it first. I have fantasized about a ring prop, you know, like the ones that come with the pull string, spring wind toys....
Could it be because as the prop RPM increases, the ring sections between the blades migrates out of round? This would be especially true for a two bladed prop unless pitch-less elements were molded in between the hub and the ring. Sure the non-flight portions would contribute to aero-resistance of some form but how much?
If we flew a successful version of this crazy idea, there would be no chance of a tip strike but certainly someone would still stick their fingers into the fan eventually.
Safeflight Copters is taking a total cage approach to the problem.
Keep thinking folks!
-=Doug
Best approach so far goes again to DJI (my personal opinion)
the Phantom prop guards are very strong and you do not have the unnecessary inner portion of the ring. they add an optional string to close the square so nothing can really go further the outside ring.
Check it out
http://www.canadadrones.com/DJI-Phantom-Prop-Guards-Canada-p/dji-ph...
It won't be the FAA it will be what ASTM F-38 tells the FAA, at the moment they are stalled.
like the Aibot X6's design which also has the prop guards. Personally I think they are great especially for things like first responders UAVs or other utility use for UAVs like wind turbine inspection, or bridge inspection.. where you want to get close but not come crashing down it you accidently make contact.
Granted the $50K price of the Aibot X6 is a bit CRAZY.
Good Point. I would like to start a discussion on the physical/aerodynamic implications of designing a prop guard for multirotors. It seems it could be useful at times even if it is not mandated by legislation.
I think the title of this article is misleading. I have not seen any information at all about FAA requiring guards.. personally I can't even imagine that being a possibility as the FAA is looking at more than just 3 lbs quad copters. Plus the FAA is concerned about the airspace.. not about a small quad copter pumping into a tree and falling.. the prop guards are not going to do anything if it was a midair collision... prop guard are really just for the end user and keeping them from making a mistake.. I really don't think FAA will ever require them... just not going to happen.