Why does the FAA Part 107 test require learning apparently unnecessary knowledge?

[DoomMeister]

If your flying a dragon fish, it will immediately revert to quad mode if a stall occured, even if that possible with a drogon fish. It's an electric motor, it won't stall. Regardless, if you talk fixed wing, then let the fixed wing flyers take the 107. Quad pilot's need and should have a different exam.

If a fixed wing aircraft under 55 pounds is flown by remote control it is considered to be an sUAS and would require §107 unless flown recreationally under §44809.

 

[DoomMeister]

DON'T YOU ALL GET IT? STALLING ONLY OCCURES IN LIQUID FUELED AIRCRAFT. Last time I checked drones are all electric. THEY DON'T STALL. The pilots of uav's have to purposely make them stall with special emergency off stick maneuvers. Why do we have special emergency shut doen procedures, because they won't turn off unless we force them too. Otherwise they don't. At least not in the way fixed air or helicopters do.

You obviously need to study for the §107 exam. The stall being discussed is not the motor/engine, but the device creating lift (wing for fixed wing aircraft or props for multi rotor aircraft).

 

[DoomMeister]

please describe a drone stall. Give me an example of a quad copter stalling due to flying like a fixed wing might stall.

Have you ever tried flying an FPV drone in Acro mode? It is very easy to stall one in that flight mode.

Most consumer drones cannot be stalled by exceeding their angle of attack as they are limited by the onboard flight controller. Add icing to the props though and it can happen due to the reduced efficiency of the props caused by the change in airfoil shape.

Your interjections into this thread are bordering on trolling. I suggest you use some thoughtfulness in your future posts.

 

[DoomMeister]

Ah easy there fella. Most folks that end up in 'Florida Man' stories are from somewhere else and come here to get their 15 minutes. We laugh at them too.

I wish we could build a wall over I 75 and I 95 to keep out those 'fleeing' their own mess but as yet, tis' only a dream. Down here the leaves don't change but the license plates do.

I resemble that remark.

 

[Ty Pilot]

I resemble that remark.

Naw, you're one of the ones that we're happy to have. Unless you suddenly feel the need to go swimming in the pond outside your house. Then you might just be a . . . . 'Florida Man'

 

[Vic Moss]

After skimming through much of this thread (like I do with all Rules and Regs thread), y'all should be happy to know that we brought up many of the issues seen here at last month's FAA AAAC meeting in D.C.

We proposed that the FAA assemble a Task Group to perform and in depth review of 14 CFR Part 107. It's been around for 7 years now, and we have the data available to use to determine where things need to change, and where things are working well. If the FAA agrees to this, we may also be able to take a look at some of the emphasis on the Initial 107 test. It's not part of when we proposed, but it would certainly be a logical offshoot of it.

We hope to get some movement on this in the next couple of months. The next AAAC meeting is in August, and the Task Group needs to be in place by then. So stay tuned. Maybe we'll see some improvement. If this comes to fruition, we'll be able to share details once the Public Book comes out. Usually two weeks before the meeting.

 

[Heavydpj]

Mind blown. In all the Youtube videos and training courses I've seen, no one has mentioned getting a Part 107 in order to fly fixed wing UAS. Good to know, and now I'm wondering: How many pilots here fly fixed wing UAS?

Yunec Firebird. However, there are quite a few that are professional grade (e.g. DeltaQuad Pro).

 

[pentatony]

Have you ever tried flying an FPV drone in Acro mode? It is very easy to stall one in that flight mode.

Most consumer drones cannot be stalled by exceeding their angle of attack as they are limited by the onboard flight controller. Add icing to the props though and it can happen due to the reduced efficiency of the props caused by the change in airfoil shape.

Your interjections into this thread are bordering on trolling. I suggest you use some thoughtfulness in your future posts.

I haven't interjected as of late. I see that I'm not educated enough to post the things that I have posted. Regarding trolling: I don't know what that is. Whatever it is, it some sort of pattern. A pattern of human behavior can be related to multiple causes. Just because this is the internet, doesn't mean "troll."

I wasn'y planning on posting again. Vheck my post patterns. I was pretty much done. I still am. The other members and you have made your points. I seriously didn't think an electric UAV could stall.

 

[DoomMeister]

I haven't interjected as of late. I see that I'm not educated enough to post the things that I have posted. Regarding trolling: I don't know what that is. Whatever it is, it some sort of pattern. A pattern of human behavior can be related to multiple causes. Just because this is the internet, doesn't mean "troll."

I wasn'y planning on posting again. Vheck my post patterns. I was pretty much done. I still am. The other members and you have made your points. I seriously didn't think an electric UAV could stall.

Your posts came across as trolling (trying to illicit argumentative or angry responses) because you were posting counterproductive information.

I understand that you have since learned a bit more about what a stall is in reference to airfoils. That is a good thing!

The part §107 exam does include information not directly applicable to drone flight, but it does relate to those we share the National AirSpace (NAS) with. If you fly your drone anywhere near an airport in Class G airspace that information really becomes invaluable in determining flight patterns and therefore where manned aircraft are likely to be.

To be honest I would really like to see something quite similar to the exam for recreational pilots that fly anywhere other than at a FRIA. Understanding the NAS, charts, and effects of weather would go a long ways in making sense of what is shown in B4UFLY, Air Control, and other similar apps. While TRUST is a small start in that direction it truly leaves a lot still lying on the table.

 

[Grandpa]

Understanding the NAS, charts, and effects of weather would go a long ways in making sense of what is shown in B4UFLY, Air Control, and other similar apps. While TRUST is a small start in that direction it truly leaves a lot still lying on the table.

My point, exactly, in a previous post.

 

[KenCharuk]

I started looking at the Part 107 practice tests, and I was struck by how much "useless" knowledge seems to be required. A good example would be learning that the wrong angle of attack causes a stall for a fixed wing aircraft. Can someone explain to me how this specific knowledge about angle of attack would ever help a drone pilot?

Much of this string focused on the fixed wing questions which kind of miss the mark. Another example is airfield signage. No drone pilot ever needs to worry about taxiway signage/designations. If you are close enough to read those signs,you are in trouble. Let's agree the 107 test needs serious work.

 

[Jamesz]

Go back one page and read post #38.

Those are all examples of propellers suffering aerodynamic stall.

Adding more weight does not increase the pitch angle of the props leading to a stall. If you tether the drone to the ground (effectively an infinite load) and try to take off, the drone attempts to rise, but has insufficient ilft to do so. It does not stall (and fall/recover). Neither does reducing power to a minimum cause stall - descending into ring vortex is is a different phenomenon.

 

[Zbip57]

Neither does reducing power to a minimum cause stall

I'll start with this one because it's the most obvious one. If you reduce power sufficiently, i.e. to the point where the motors stop and the props cease sweeping through the air, that will most certainly cause the blades to stall and the drone will drop.

Otherwise, if the motors are turning the props fast enough, and enough air is fed to the props, they will run efficiently and not stall. Still, there is a point between those two extremes, where the motors are turning slowly enough (not yet stopped), at which the blades definitely will suffer aerodynamic stall.

You will typically never encounter this type of prop stall because it's the flight controller is programmed to ensure the motors never run that slowly. If you insist on flying your drone until the battery is depleted, the flight controller is also programmed to repeatedly warn you and eventually it will even attempt an elegant auto-landing. But if you force it stay to aloft until the battery is dead, your props absolutely will stall out.

- descending into ring vortex is is a different phenomenon.

Yes, it is. Because here the prop blades are obviously stalled.

The pitch angle of the prop blades, relative to the motor axis and aircraft body, is fixed and doesn't change. In stagnant air, the prop blade generates lift as it sweeps forward through the air. But in a vortex ring state, the airflow is effectively blowing straight down onto the top of the blades.

What matters here is not the fixed pitch angle of the blade relative to the motor shaft, it's the angle between the propeller blade and where the airflow is coming from. If the airflow is no longer flowing smoothly over the surface of the prop blade, but instead becomes separated from the surface and turbulent, that is what causes aerodynamic stall.

DJI's Phantom series were prone to vortex ring state when descending too fast straight down into their own propwash. Firmware on newer drones put a limit on descent rate. Now, even if descending straight down, the drone can't descend fast enough to ever encounter vortex ring state.

Adding more weight does not increase the pitch angle of the props leading to a stall. If you tether the drone to the ground (effectively an infinite load) and try to take off, the drone attempts to rise, but has insufficient lift to do so. It does not stall (and fall/recover).

Close, but no cigar.

Tethering is not effectively an infinite load. The tension in the tether is not equivalent to full weight of the Earth. The tension is merely equal to the maximum lift capability of the partially stalled props.

For a better illustration, try suspending a weight from your drone, then launch the drone from some height. At some critical load the drone will only just barely be able to support itself and the load. That scenario is then the equivalent of your tethered example.

Now add increasingly heavier loads and eventually the drone will be unable to sustain lift and will drop to the ground. If it only sinks slowly, then the props are only partially stalled out but still producing some lift.

Clearly there will be some finite weight limit after which the drone drops like a rock from the sky no matter how fast the motors are trying to spin the prop blades. If the drone is still in level attitude, but being dragged straight down fast enough by a heavy enough weight, what direction is the airflow going now relative to the fixed pitch angle of the prop blades?

The air is no longer flowing smoothly over both the upper and lower surfaces of the blade, as it would normally when the blade is slicing forward through stagnant air. Instead, if the drone is falling fast enough, the airflow is now blowing straight UP separating past the leading and trailing edges of the propeller blades. That's definitely aerodynamic stall.

Adding more weight does not increase the pitch angle of the props leading to a stall.

It most definitely does.

And the effect happens not only through increasing weight through added payload, it can also occur even without any added payload but in high-g flight manoeuvres.

Camera drones are typically firmware limited to prevent high-g flight stresses, but high-performance FPV drones can be flown into attitudes where the propellers lose bite and simply "mush" through the air when overloaded.

 

[Jamesz]

Thanks Zbip57 for pointing out my somewhat elementary errors:I'd been too quick dismiss the effect of high AofA caused by descent etc, I was blinded by the props fixed pitch maintaining a consistent attack angle.
The tethered analogy was indeed incorrect, as as you point out, the greatest load here is simply the max thrust the drone can provide, which coud easily be exceeded by a sufficiently large payload.

 

[Xitor]

Only loosely related to your question, but saw a news spot recently about a school that had a drone program, "drone soccer" actually and two of the students say this influenced them to want to go into aviation.

""I really didn't know how my life was gonna end up, and now I can see a path for me so it's something amazing," said Culp. He will soon go to college for aviation and aerospace engineering, while Galler has now gotten her professional drone's license and private pilot's license. She hopes to one day become an astronaut."

"Westminster High School students headed to South Korea for drone soccer tournament"

 

[gajman]

AFAIK, Part 107 includes all drones, including fixed-wing models. I could be wrong about that, though.

I know that in Canada our sRPAS license includes all remotely-piloted aircraft, not just quadcopter drones. So our test includes questions like that because they are relevant to some sRPAS pilots.

There are a number of fixed-wing drones available.

 

[AnzacJack]

Mind blown. In all the Youtube videos and training courses I've seen, no one has mentioned getting a Part 107 in order to fly fixed wing UAS. Good to know, and now I'm wondering: How many pilots here fly fixed wing UAS?

I fly multiple fixed wing and vtol UAS

 

[AnzacJack]

If your flying a dragon fish, it will immediately revert to quad mode if a stall occured, even if that possible with a drogon fish. It's an electric motor, it won't stall. Regardless, if you talk fixed wing, then let the fixed wing flyers take the 107. Quad pilot's need and should have a different exam.

Would you be suggesting a different exam for the various different aircraft and configurations? Then maybe differnt qualifications? Multiple exams and qualifications for those that fly various craft?
Its not going to happen anytime soon. I hope..

 

[Bill Ballard]

Preface: I didn't read all of the posts/responses in this thread. That said, to answer the OP's original question - there is no understanding of these things.

When I worked as a maritime accident investigator, investigating accidents involving ships, yachts, commercial fishing boats, etc., one client insisted I obtain an insurance adjustor's license for their state. In order to be licensed to investigate any insurance claim involving a ship and it's cargo, or a yacht, or a crew member injury in said state, I had to pass a written exam. Fair enough.

What would I be tested on? Auto, General Commercial Liability, Medical, and Agricultural.

Yep.

 

[KenCharuk]

After skimming through much of this thread (like I do with all Rules and Regs thread), y'all should be happy to know that we brought up many of the issues seen here at last month's FAA AAAC meeting in D.C.

We proposed that the FAA assemble a Task Group to perform and in depth review of 14 CFR Part 107. It's been around for 7 years now, and we have the data available to use to determine where things need to change, and where things are working well. If the FAA agrees to this, we may also be able to take a look at some of the emphasis on the Initial 107 test. It's not part of when we proposed, but it would certainly be a logical offshoot of it.

We hope to get some movement on this in the next couple of months. The next AAAC meeting is in August, and the Task Group needs to be in place by then. So stay tuned. Maybe we'll see some improvement. If this comes to fruition, we'll be able to share details once the Public Book comes out. Usually two weeks before the meeting.

I think the focus needs to be on operational safety. Too many of the questions seem to be plucked from existing non-drone exams. Airport signage? Flight restrictions over 400 feet? I would be willing to write some questions!