Drone Exemptions 1

[BUGGAR]

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.

 

[berkshire]

Buggar,
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.

 

[berkshire]

Drones are considered to be either UAV's or MODEL AIRCRAFT by the FAA . Here is a link to proposed regulations of Model aircraft.

You are judged not by what you know, but by what you can do.

 

[IRstuff]

Note that there's some over-specification at play; it's unlikely that the quadcopter is actually doing 100 mph in the middle of its inspection, as there is no way the operator could possibly check the video feed fast enough for that speed. Since it is a quadcopter, it can do its work at near zero air speed, which means that if it loses power, it'll pretty much fall straight downward, with perhaps only a little lateral motion due to the lift of the rotors.

TTFN
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[BrianPetersen]

Are these various dimensions and limits being applied and enforced on a worst-possible-case condition prior to being able to operate the device ... or are they only being applied and enforced subsequent to an accident in which it is found that one of the dimensions is being violated?

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.

 

[GregLocock]

With a CdA of 0.0, ie worst case for drag, you'd need an exclusion zone of 780 feet, and the thing would hit the ground at roughly 150 mph. With CdA=0.23 m^2 it hits at 85 mph. This assumes horizontal elevation at first, which is not worst case, and that the thing is purely ballistic.

These are fascinatingly large numbers.



Cheers

Greg Locock


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[KENAT]

Also assuming flat ground and no wind - which FAA or whoever may or may not consider valid assumptions.

Do they not give any guidance for how to perform the calculation or at least what assumptions you should make?

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[KENAT]

Oh and what about factor/factor of safety - I'd be surprised if they wanted less than say 1.5 times whatever you calculate but could well be wrong.

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[BrianPetersen]

All of that is why I suspect that there is not a requirement to prove that a violation can never physically happen (as it would be essentially impossible to ever do this), but only either applied "as written", or perhaps after the fact in the event of an incident.

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!

 

[KENAT]

You say that but...

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.)

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[BrianPetersen]

The question needs to be asked of the regulatory authority if the wording of their requirement is unclear:

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.

 

[KENAT]

"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"

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!

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[BUGGAR]

"This assumes horizontal elevation at first, which is not worst case," VERY significant point, Greg! Drone Kid and I watched hours of films of drone crashes and what you say, we frequently saw.

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.

 

[tbuelna]

Here's what FAR part 91.119 says:

"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. "

 

[berkshire]

Apparently these people did not get the message.

You are judged not by what you know, but by what you can do.

 

[BUGGAR]

I see that the FAA has issued FAA 333 Exemption No. 12602 to Peter Sachs to operate a Tailor Toys powered paper airplane. Is it fair to limit a paper airplane to 100 mph and an altitude of 400 feet?

 

[3DDave]

berkshire - one of these days a plane will hit a drone, but so far I haven't seen a photo of a drone near a forest fire or commercial or private aircraft. Now the DoT/FAA is proposing requiring registration of what seems like every R/C model operator.

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-midair-plane-crash-private-plane-n388046

and

http://www.cnn.com/2015/10/14/us/lake-worth-florida-plane-crash/

and

https://www.washingtonpost.com/loca...913716-7ef2-11e4-8882-03cf08410beb_story.html

(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/inv.../12/08/gaithersburg-crash-rosenberg/20116417/

At least Rosenberg won't get any more chances to kill others.

 

[itsmoked]

Sorry 3DDave, but you should just resign yourself to the eventuality of licensing. It's the tried-and-true method of gaining some semblance of control over something. Especially, something being embraced by and enabled for the world's growing number of clueless and defiant morons.

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

 

[IRstuff]

Now, after that we can look at ways of shooting them down ;-)

TTFN
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[BrianPetersen]

At this point, with the registration / licensing ship having sailed, I think legalizing shooting them down if they are over your property or looking into your property or otherwise presenting a risk to you, would be the more effective option ... and more interesting, too ...

 

[3DDave]

I would rather they focus efforts on ensuring the drones are reliable and secure. There's too many stories of 'Heading back to China' failure modes and channel interference causing erratic behavior, neither of which requiring owners to get licenses will affect.**

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.