DJI P4P - High Altitude Operations

[The Editor]

I've never measured it, but according to DJI specs, climb rate is 1,000 feet in a little under a minute. Powered decent rate is about 800 feet in a little under a minute. So when I was putting all this together to see if it was even feasible to do it, I was allowing 4 minutes to climb, and allowing 5 for decent. For our high-power flights, we give a 10 minute heads-up call to ATC and they give us a 20 minute launch window starting at that point. So 5 minutes before launch, put the P4P in the air and get positioned. I figure that gives me 10 solid minutes to hang out, then another 5 to return. 20 minutes total flight time, which is the same as our launch window. I think it's doable, especially if they are able to launch on the first hit without me having to loiter around for 10 minutes.

4 minutes at climb out circa full throttle...... and you think your pack will give you 20 minutes total flight time after starting off like that????????

 

[RNCotton]

4 minutes at climb out circa full throttle...... and you think your pack will give you 20 minutes total flight time after starting off like that????????

You're the professional, so would you mind sharing with the class? Will it?

 

[The Editor]

You're the professional, so would you mind sharing with the class? Will it?

No.
You will be drawing maximum C/current from the pack and into increasing altitude and thinner air which means your motors will work even harder maintaing lift/thrust. The props will become less efficient as you climb.
To attempt a flight like this you would need to factor in your MTOM of your aircraft, the KV rating of your motors, and length and chord of your props. Thus thrust per corner (for a quad) and factor in some sort of overhead, maybe 20% for safety.

If you are not comfortable with working on this you maybe should not be attempting the flight.
I would have thought your countries aviation authority would want details of your flight contingency procedures as well as alternative landing areas and boldface procedures before they would even entertain any sort of OSC for non standard ops.
Maybe things are done differently in States.

 

[RNCotton]

No.
You will be drawing maximum C/current from the pack and into increasing altitude and thinner air which means your motors will work even harder maintaing lift/thrust. The props will become less efficient as you climb.
To attempt a flight like this you would need to factor in your MTOM of your aircraft, the KV rating of your motors, and length and chord of your props. Thus thrust per corner (for a quad) and factor in some sort of overhead, maybe 20% for safety.

Unnecessary snarkiness aside, thank you for your information and contribution to the discussion on feasibility of a flight.

 

[The Editor]

Unnecessary snarkiness aside, thank you for your information and contribution to the discussion on feasibility of a flight.

Assuming you were even able to circumvent the hardware barometer limitation of 500m agl and aside from the actual logistics calculations, how would your current insurance carriers view a non standard operation over and above the operating ceiling of your aircraft?
I would imagine any claim/liability would be swiftly denied.

 

[Moosewax]

No.
You will be drawing maximum C/current from the pack and into increasing altitude and thinner air which means your motors will work even harder maintaing lift/thrust. The props will become less efficient as you climb.
To attempt a flight like this you would need to factor in your MTOM of your aircraft, the KV rating of your motors, and length and chord of your props. Thus thrust per corner (for a quad) and factor in some sort of overhead, maybe 20% for safety.

If you are not comfortable with working on this you maybe should not be attempting the flight.
I would have thought your countries aviation authority would want details of your flight contingency procedures as well as alternative landing areas and boldface procedures before they would even entertain any sort of OSC for non standard ops.
Maybe things are done differently in States.

Yeah I agree, the snarkiness was uncalled for, RNCotton you handled it well, I need to take your example to heart.

You have many valid points Editor, but the FAA in the USA has many challenges and issues facing it, and right now we have a generally laissez-faire regulation environment so long as you pass a test showing you know enough about airspace regulations. There is little to no technical knowledge required to operate legally. It is a double edged sword, gives a lot of people room to operate with minimal red tape but also means there are a lot of people operating with little to no guidance. Its on the indvidual to learn and become proficient. Which, by RNCotton participating here he is displaying that he is taking the time to learn. Everyone starts the journey sometime, no need to lord over that you seem to be further along that journey with its extra knowledge.

Eventually the USA might get there, but too many people high up focused on delivering burritos and stupid things like that, to have any brains left over to focus on proficient operator standards, in my opinion.

 

[Moosewax]

Assuming you were even able to circumvent the hardware barometer limitation of 500m agl and aside from the actual logistics calculations, how would your current insurance carriers view a non standard operation over and above the operating ceiling of your aircraft?
I would imagine any claim/liability would be swiftly denied.

That is a good point, he would have to contact his insurance broker, and then assuming they actually know anything too many of the drone insurers seem to know jack squat.

The aircraft would be within its operating ceiling as I understand it, the 1600ft AGL limit from takeoff is arbitrary and imposed by software. Nothing to do with the physical/operational limitation of the aircraft.

There are videos of goofballs taking an older phantom model to over 10,000ft.

 

[BigAl07]

Ok gang this forum is considered "Professional" so we tend to let more slide here than on other forums owned and operated by the same group. But this thread is getting borderline and we don't need to let it keep degrading.

With that being said we do need to take the "Tone" down a notch and understand not everyone is at the same level of experience and knowledge and be a bit more "supportive" and less abrasive. We all started at the same level and we all have more we can learn regardless of how many hours we already have logged.

One last note, keep in mind this is an INTERNATIONAL forum and it's easy to forget that others may talk/think/type a bit differently than we do and they may not mean it to sound as "harsh" as we have taken it. This goes as much for me as it does any other member on this forum.

Safe professional flights to ALL
Allen

 

[The Editor]

That is a good point, he would have to contact his insurance broker, and then assuming they actually know anything too many of the drone insurers seem to know jack squat.

The aircraft would be within its operating ceiling as I understand it, the 1600ft AGL limit from takeoff is arbitrary and imposed by software. Nothing to do with the physical/operational limitation of the aircraft.

There are videos of goofballs taking an older phantom model to over 10,000ft.

Yes but those goofballs are not operating commercially - they are just future Darwin award winners.

The OP was talking about ops up to 4,000ft agl which would go past the 500m/1600ft limitation.
Any flight past that 500m limit would require hardware/firmware alterations to ignore the data or alter it from the onboard barometer and onto the flight controller once past 500m (zero from take off), otherwise the brakes would come on rather rapidly.

 

[skyeboysteve]

I've never measured it, but according to DJI specs, climb rate is 1,000 feet in a little under a minute. Powered decent rate is about 800 feet in a little under a minute. So when I was putting all this together to see if it was even feasible to do it, I was allowing 4 minutes to climb, and allowing 5 for decent. For our high-power flights, we give a 10 minute heads-up call to ATC and they give us a 20 minute launch window starting at that point. So 5 minutes before launch, put the P4P in the air and get positioned. I figure that gives me 10 solid minutes to hang out, then another 5 to return. 20 minutes total flight time, which is the same as our launch window. I think it's doable, especially if they are able to launch on the first hit without me having to loiter around for 10 minutes.

I doubt you'd get more than 16-18 minutes total flight time (especially if there's 20mph+ winds aloft) if you're climbing at full throttle to get to 4,000' as fast as possible. Your total time to climb and descend will be greater than 10 minutes; as your climb rate will diminish. If you're going to hack the altitude limit you might want to hack the vertical descent speed too; to give you more time aloft and less time descending.

I hacked mine when I traveled overseas to a remote mountainous island with no air traffic for hundreds of miles around. I doubled my descent speed with the plan to always fly laterally during rapid descent to avoid any potential VRS--though I noticed that when I flew forward at full speed; my vertical descent would slow significantly for some reason.

 

[R.Perry]

I just learned something, I didn't know what the P4P clime rate is. I'm assuming that is at sea level and 70 degree day, that is just a guess on my part. As I'm sure you are aware the hotter it is your climb rate will be reduced. Now if you were launching in Lake Tahoe or Colorado Springs you would be looking at a much lower climb rate.

As Big A said, many pilots have bit the farm because they didn't pay attention to the density altitude, sounds like you have it figured out fairly well.

 

[RNCotton]

Thanks for all the open and candid discussion.

With firmware limitations, VLOS restrictions, and all other things considered, I think our best option will be to look at 1,500 feet as our target. It will still allow us some decent views of the launches, especially if we go with a low-thrust ./ long burn motor in the rockets which will give a nice slow launch that builds up speed over time rather than a single hard hit off the pad and then basically coasting to apogee.

1,500 is feasible from a battery standpoint, and we can keep VLOS on the aircraft, especially if we add some aux lighting. We have the airspace for the the launch window, and we still do a sky/range check immediately before launch.

On the flip side of all this .... since this is just for my own entertainment, wouldn't this flight be recreational, and therefore more subject to "recommendations" rather than FAA Rules?

 

[Dave Pitman]

How large are your rockets? Do you think you will be able to anticipate the position the Phantom will need to be to capture the rocket as it ascends? With a wide angle lens, that seems like it would be very hit and miss just thinking about it.

 

[RNCotton]

How large are your rockets? Do you think you will be able to anticipate the position the Phantom will need to be to capture the rocket as it ascends? With a wide angle lens, that seems like it would be very hit and miss just thinking about it.

These are pretty big ... 5 to 8 inch diameter, 4 - 8 feet length.

We know the course trajectory, short of a CATO or other malfunction, so positioning the camera to film the launch / flight won't be an issue.

 

[Dave Pitman]

Sounds like fun !

 

[BigAl07]

On the flip side of all this .... since this is just for my own entertainment, wouldn't this flight be recreational, and therefore more subject to "recommendations" rather than FAA Rules?

Since you're already on the FAA Radar having an authorization for rockets up to 6500ft I don't think I'd opt to try and hide behind the "Hobby" veil especially since you have your Part 107 and know better/different.

But the above if just my own personal , non-legal, shoot from the hip advice and nothing more. I pretty much "protect" my Part 107 at all cost and try to never put it in jeopardy because my Part 107 is my bread and butter.

 

[RNCotton]

Since you're already on the FAA Radar having an authorization for rockets up to 6500ft I don't think I'd opt to try and hide behind the "Hobby" veil especially since you have your Part 107 and know better/different.

Yeah, my comment was tongue-in-cheek. I'm the same way. I have 107, I know better, and I'm not going to ever just skirt the rules behind a hobby/rec designation.

 

[R.Perry]

I have a question, I know go figure. What altitude will you be launching from? If near sea level I don't think you are going to have much of a problem with air density. I know on my aircraft rate of climb was pretty consistent until I got past the 5000 foot elevation. That is on a naturally aspirated engine ( no turbo, and gas).
Yes you are going to use more power climbing, but less descending. If it were me I and I could get the authorizations I would take a test flight up to your desired altitude, then bring it right back down, once you land see what you have left in your battery then estimate how long you can stay at altitude to do the filming remembering that you will use a bit more power at 4000 ft than sea level.
Air temp on the day of the flight can also be a factor, and I would shoot for a nice cool day with stable air.

 

[Meta4]

There are videos of goofballs taking an older phantom model to over 10,000ft.

But they are hoaxes.
The highest genuine one was probably just short of 5K ft.

 

[Meta4]

I would take a test flight up to your desired altitude, then bring it right back down, once you land see what you have left in your battery then estimate how long you can stay at altitude to do the filming remembering that you will use a bit more power at 4000 ft than sea level.

He can't get up to his desired altitude.
The Phantom won't go past 1640 feet.