Drone Exemptions
Drone Exemptions
(OP)
I’m working on an FAA Exemption for a client to fly commercial drones. A typical FAA requirement is to fly no faster than 100 mph and no higher than 400 feet above ground level. Also, your operational boundary has to be 500 feet away from someone you don’t want to hit. Before I do the math, does anyone know drone aerodynamics to determine if a 55 lb drone going 100 mph at 400 feet altitude will fall within the 500 feet safety zone if power and control quit immediately? This would be a quadcopter type drone, not a glider.
Of interest: a 55 lb drone at 400 feet has 22,000 ft lb of energy, same as a 4 ft x 8 ft x 1inch steel road plate falling from 17 feet. A drone freefalling from 400 feet with no air drag will hit the ground at 110 mph.
Thank you everbody.
Of interest: a 55 lb drone at 400 feet has 22,000 ft lb of energy, same as a 4 ft x 8 ft x 1inch steel road plate falling from 17 feet. A drone freefalling from 400 feet with no air drag will hit the ground at 110 mph.
Thank you everbody.





RE: Drone Exemptions
Cheers
Greg Locock
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RE: Drone Exemptions
RE: Drone Exemptions
It depends on too many specific factors, but the QC would take 5 seconds to fall the ground with no air resistance. 5 seconds * 100 mph = 733 ft. Air resistance downward would be higher than air resistance laterally, so a more realistic calculation would probably still allow the copter to reach 500 ft.
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RE: Drone Exemptions
The equation for ballistic trajectory in the presence of drag is not analytically solvable, the easy way is a numerical sim. I'll see if I get time today.
Cheers
Greg Locock
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RE: Drone Exemptions
I'm with IRstuff on this one, I calculate 4.99 seconds to fall to earth and it would have covered a distance of 739 Ft horizontally before hitting the ground but without considering any air resistance.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Drone Exemptions
RE: Drone Exemptions
http://andrew.gibiansky.com/blog/physics/quadcopte...
http://andrew.gibiansky.com/downloads/pdf/Quadcopt...
http://www.ijstr.org/final-print/aug2014/Quadcopte...
http://sal.aalto.fi/publications/pdf-files/eluu11_...
http://www.europment.org/library/2014/santorini/by...
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RE: Drone Exemptions
I tried to talk him into trying a 100 mph free fall from 500 feet up with one of his drones and he came up with the drone on a string out of the car idea instead. This sounds more fun than doing it on a computer. But I'd rather test crash one.
RE: Drone Exemptions
I'd probably use a CD value for a sphere of approximately equivalent cross section in the 'lowest drag' orientation.
Don't forget to add a good margin of error.
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RE: Drone Exemptions
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RE: Drone Exemptions
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RE: Drone Exemptions
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RE: Drone Exemptions
However, you probably still need to provide some liability insurance coverage for your activities. And I imagine it would be very difficult (and expensive) to obtain this type of coverage.
RE: Drone Exemptions
Cheers
Greg Locock
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RE: Drone Exemptions
That looks like a good number. Drone Kid and I went to a drone shop to see what was available. The ratio of weight to projected area (and Cd) of all the drones we saw varied so much that we would have to prequalify a specific drone for a specific use. We looked at some 55 pound drones that are allowed by FAA. These things are monsters and you do not want one falling on you from 400 feet.
Your Cd area of 2.5 square feet breaks down approximately to a 1.6 ft. x 1.6 ft. size drone (solid area). We didn't measure the 55 pounders but I estimate that their area is less than that, and they would have to descend in the "projected area" position which isn't likely. Therefore, in all probability, their kill zone is beyond the FAA horizontal limit. There are lawyers that specialize in applying for FAA exemptions. Don't they read these things?
Can you tell me what simulator you used for the drag coefficient?
Thanks.
RE: Drone Exemptions
RE: Drone Exemptions
http://www.mediafire.com/download/ox6sj50sc0lyjdr/...
Cheers
Greg Locock
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RE: Drone Exemptions
During my research, I found out that drones are being operated by a local utility to inspect their powerlines and facilities. They are operating drones at a nearby substation with 38 houses and an open space park in the "kill zone" of their drones (laterally within 730 feet from drone operations).
I have sent a letter to the FAA and the Utility. This is a politically powerful utility here and if you don't hear from me, I'm probably in a buried electrical vault somewhere.
These Exemptions are public information and are internet-searchable under FAA Section 333 Exemptions. The one for the subject utility is Exemption No. 11238. Most of these Exemptions seem to rely on the blanket 500 ft lateral/400 vertical/100 mph rule. I argue that they should be site-specific. Can't drones be preprogrammed for these variables?
Greg, special thanks for the chart. Your Cd looks like it may fit some of the drones we looked at but when we compared some that had similar weights, their configuration (and Cd) were radically different from each other.
RE: Drone Exemptions
RE: Drone Exemptions
That would appear to be close to Montgomery Field and Miramar airbase . Are you sure you are not within the 5 miles from an airport restriction.
B.E.
You are judged not by what you know, but by what you can do.
RE: Drone Exemptions
You are judged not by what you know, but by what you can do.
RE: Drone Exemptions
TTFN
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RE: Drone Exemptions
It's illegal to drive your car on the wrong side of the centerline marking in an area where signs prohibit it. But the auto manufacturers are not required to build a vehicle which is IMPOSSIBLE to drive on the wrong side of the centerline marking.
It appears that you are trying to do the latter, but the actual application may be more similar to the former.
RE: Drone Exemptions
These are fascinatingly large numbers.
Cheers
Greg Locock
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RE: Drone Exemptions
Do they not give any guidance for how to perform the calculation or at least what assumptions you should make?
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RE: Drone Exemptions
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drone Exemptions
If your operational boundary is required to be 500 feet away then that's how close the operator is allowed to fly ... not 500 feet plus an enormous allowance in the event of some sort of failure. The 500 feet is understood to already contain the allowance for not falling straight down, etc.
If the drone encounters a F5 tornado then it's going to be blown wherever the tornado wants to blow it, no matter what calculations you do!
RE: Drone Exemptions
Back when dropping things off aircraft intentionally our 'safety zones' would be massive by the time all margins of error/safety etc were taken into account.
Most military ranges are a lot bigger than '500 ft' but we'd often still have to be very careful that our foot print was fully in the range.
(Yes we were flying faster and sometimes higher but hopefully you get my point.)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drone Exemptions
Is the 500 foot distance "as written" or does it apply to equipment failure or other such conditions, and if so, what are those conditions.
Over-analysing something isn't a constructive exercise, and applying safety factors on top of something that already has a safety factor built into it will just make it impossible to get through the exercise.
RE: Drone Exemptions
Or not, worked on a project where something in the air stream needed its 1.5 factor on it which was duly done based on aero loads supplied by the customer. The part was pretty beefy but met it's required strength per calculation, FEA & testing.
Only after all this did the customer tell us the loads they'd given us already had the 1.5 in them.
Oh well, that particular piece of conduit is, and for ever will be at least 2.25 times stronger than the max predicted aero load and the safety approval folks were OK with that!
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drone Exemptions
We went back to drone shop and interviewed a few "professional" drone pilots, one an ex-military drone guy. Most important, we learned is that it is easy to pre-program a flight envelope, including air speed, into a drone. The better Geo-fences are accurate to a meter or less with GPS, and tighter tolerances are available with ground based positional stations.
So now my campaign turns to convincing FAA to add flight pre-programming as a primary restriction for drone use at this facility. This should be easy by adding an amendment to the Exemption, which is frequently done to add an additional drone to the Exemption. I sent a letter with copies of Google earth showing the "kill zones" in the local neighborhoods and park. I also have our City Councilmember involved but he's so busy saving the Chargers that he won't be of any help. The electric utility involved no doubt has a contract out on me. I'll keep you posted on this.
RE: Drone Exemptions
"91.119 Minimum safe altitudes: General.
Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:
(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
(b) Over congested areas. Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.
(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure. "
RE: Drone Exemptions
You are judged not by what you know, but by what you can do.
RE: Drone Exemptions
RE: Drone Exemptions
Which is strange as there are millions of camera phones in use. There isn't even footage of a place in the sky where the witness says the drone was or a map coordinate or any evidence at all. It's beginning to seem more like the UFO sightings and ball lightning sightings. Scuttlebutt on pilot forums is the FAA is suggesting pilots report anything they are unsure of as drones, just to be safe. Plastic bag in a thermal - it's a drone. Helium balloon - it'd a drone.
Meanwhile private planes continue to claim innocent lives by crashing into homes or into low-altitude, high speed military aircraft.
http://www.nbcnews.com/news/us-news/reports-f-16-m...
and
http://www.cnn.com/2015/10/14/us/lake-worth-florid...
and
https://www.washingtonpost.com/local/crime/plane-c... (from the article "it was the second time that Rosenberg had crashed while landing at the Montgomery County Airpark")
Sorry - it angers me that the FAA and DOT are whining about unconfirmed reports of bad things drone pilots might have done while it's A-OK for a guy with the bucks to buy a twinjet (to replace his crashed twin turboprop) and incinerate a mother and two sons because he didn't really know how to cope and already had one pilot-error crash. http://www.wusa9.com/story/news/investigations/rus... At least Rosenberg won't get any more chances to kill others.
RE: Drone Exemptions
It's needed so a set of rules can be verifiably received by each drone user. If you have to pass a test based on the rules and be licensed to operate then said morons can be effectively grounded if found necessary. Otherwise they claim ignorance when caught doing dangerous things.
I see this being done similarly to HAM radio licensing, but due to the plethora of bad examples it may end up being governmentally administered perhaps via DMVs or such.
I don't see drone flying as anything less than driving a car, I want to continue seeing people who are handed driver's licenses being checked in some way for fitness to the task.
If an airliner is brought down by a drone drones will likely be banned for all except licensed pilots. Surely requiring casual drone operators to be licensed before that happens is better for the drone community then the alternative?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Drone Exemptions
TTFN
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RE: Drone Exemptions
RE: Drone Exemptions
Crashing a jet liner with a typical hobby drone is unlikely; if it happens it will be an unlicensed operator with a purpose built device doing so intentionally. But since that's an unreliable method, it seems unlikely for any but a nut job to even try; again, not going to have a license.
Instead the US will have a huge, and valuable data repository of identity information, ripe for the hacking in the hands of departments with little information security experience; it will also have a large number of new employees to manage; and it will have a new revenue stream for an ineffective result. Maybe everyone should be fingerprinted and DNA aamples taken as a way to curb other crimes, which is effectively what I just saw the head of the US DoT suggest was the reason for licensing - to make it easier to catch criminals.
Unavoidable - sure, no question. But also a waste of time and resources and a new source of risk to the people forced to participate.
**My favorite was an attempt to fly around a rock tower ~300 foot tall and 100 foot wide. When the drone lost signal it did a return to base - straight line to the take-off coordinates, which was directly through the tower. It could have been programmed to return to last-good-signal point or back-track it's path. The fliers got it back, but it was damaged.
RE: Drone Exemptions
RE: Drone Exemptions
I think you will find that bird attacks account for less than 1% of all quad crashes, so not statistically significant - although they are really really cool to see!
Since laws, regulations, registrations,and penalties only work on those on whom they will work, it means drone regulations will only hinder those of us who fly responsibly; those who don't, still won't, since they have, and always will, ignore them.
"Ignorance of the law is no defense" still applies, so those who fly irresponsibly are not off the hook as it stands now anyway.
So more regulations serve no useful purpose except to extract more money from us who pay taxes and fees. But it is like building 100 new houses in a city: the extra tax income base does not pay for all the additional infrastructure required, so it really doesn't even work. That will be true here also.
www.KilroyWasHere<dot>com
RE: Drone Exemptions
I noticed the Exemption had no electrical qualification requirements for drone operators that will be operating around the electrical equipment. I sent a letter to IBEW so they could get their requirements addressed as well.
RE: Drone Exemptions
I'm challenging the FAA exemption for not complying with the requirements of the situation. I'm a structural engineer and I write contracts all the time for small and large construction projects. We use standard contract forms like those from AIA and CASE and then modify them with an appropriate Special Conditions clause that stipulates details such as I am proposing. Not a big deal in the construction industry. Of course I'm beating a dead horse, but I do enjoy the comments I'm getting from FAA. I enquired about the use of a geofence with drones and they thought I was talking about temporary barricade fencing to keep people away from drone launch sites.
RE: Drone Exemptions
I recently went to Walmart, asked the computer salesperson where the UPS's were. She insisted I wanted USBs. She eventually said "honey, UPS is who brings our stuff. you want USB." she could work for the FAA!
But Buggar, pray tell, what is a IBEW? some electrical union?
www.KilroyWasHere<dot>com
RE: Drone Exemptions
Sounds like you are stirring up the doodoo.
I betcha that 500 foot requirement was just pulled out of a hat with no real thought put into it, nor was there ever any real expectation of someone analysing it to death. Probably all of the other numbers are from that same hat.
RE: Drone Exemptions
RE: Drone Exemptions
www.KilroyWasHere<dot>com
RE: Drone Exemptions
B.E.
You are judged not by what you know, but by what you can do.
RE: Drone Exemptions
RE: Drone Exemptions
This should be useful to you if you do not already have it.
B.E.
You are judged not by what you know, but by what you can do.