High altitude 1360x prop question FINALLY answered...

[Donnie Frank]

Hey doods;

So there are like a half dozen threads going right now regarding altitude props. So instead of replying to all of them, I thought I would simply start a new thread.

After sending DJI somewhat of a nasty gram regarding the lack of information available, and lack of knowledge from their chat support regarding these altitude props, apparently a "real technician" finally responded to my email and gave a succinct answer. Only took 3 weeks!! I screen captured so you would know exactly what I received. FINALLY, a REAL answer to the burning question.



This seems to jibe with Inspire pilots' real-world experience. I tested the props @ 5200' MSL, and my results were not good.

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Regards,

D

 

[YeeaaBoii]

Good job at finally getting an answer on some solid numbers from DJI! I am currently in Durango, CO where the elevation is around 9,000ft and have been using the high altitude props. We also snowmobiled up to 11,000ft and flew it from there. I live and normally fly in Dallas, TX.

I did a test near 9,000ft with the standard props vs the high altitudes and noticed a huge difference.

Aircraft: DJI Inspire 1 Pro with X5 camera.

Standard Props
- Standard props were obviously spinning much faster and it took almost full stick to get the Inspire off the ground.
- While hovering with the standard props, I constantly got the "motor overload" notification.
- With full stick up, I could only increase altitude at 5mph.
- All other movements of the aircraft took much more stick input than normal to move.
- Battery life didn't seem to take a hit, which was surprising. Maybe 1 minute less than normal.

High Altitude Props
- Noticeably quieter and RPMs obviously lowered.
- Took half the amount of stick input to take off. (Felt like sea level take off with standard props)
- I only received "motor overload" notification when increasing altitude at full throttle.
- All other movements felt solid and required a normal amount of stick input.
- Battery life was comparable to results I get near sea level. Definitely NO decrease in flight time.

Hope that can help some people out. I would definitely recommend the high altitude props if you are going to 8,000ft or above like the DJI rep suggested in the OP's post.

 

[pulsar747n]

I don't know for sure but;
Higher pitch props (1360) put more load on the battery and will give the sensation that the bird is more responsive in a climb. Also, maybe more quiet because lower RPM?

 

[The Editor]

Hey doods;

So there are like a half dozen threads going right now regarding altitude props. So instead of replying to all of them, I thought I would simply start a new thread.

After sending DJI somewhat of a nasty gram regarding the lack of information available, and lack of knowledge from their chat support regarding these altitude props, apparently a "real technician" finally responded to my email and gave a succinct answer. Only took 3 weeks!! I screen captured so you would know exactly what I received. FINALLY, a REAL answer to the burning question.

View attachment 11767

This seems to jibe with Inspire pilots' real-world experience. I tested the props @ 5200' MSL, and my results were not good.

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For more detailed information, see our cookies page.

Accept third party cookies

Regards,

D

I answered this back in March last year on another thread but the DJI 'tech' doesn't really answer the entire question or go into the risk of cavitation if the HA props are used at lower altitudes. Although true cavitation does not occur in air (since it's physical form cannot be altered like water) but stalling can occur because of the angle of attack of the propeller resulting in loss of thrust

 

[Donnie Frank]

Good job at finally getting an answer on some solid numbers from DJI! I am currently in Durango, CO where the elevation is around 9,000ft and have been using the high altitude props. We also snowmobiled up to 11,000ft and flew it from there. I live and normally fly in Dallas, TX.

I did a test near 9,000ft with the standard props vs the high altitudes and noticed a huge difference.

Aircraft: DJI Inspire 1 Pro with X5 camera.

Standard Props
- Standard props were obviously spinning much faster and it took almost full stick to get the Inspire off the ground.
- While hovering with the standard props, I constantly got the "motor overload" notification.
- With full stick up, I could only increase altitude at 5mph.
- All other movements of the aircraft took much more stick input than normal to move.
- Battery life didn't seem to take a hit, which was surprising. Maybe 1 minute less than normal.

High Altitude Props
- Noticeably quieter and RPMs obviously lowered.
- Took half the amount of stick input to take off. (Felt like sea level take off with standard props)
- I only received "motor overload" notification when increasing altitude at full throttle.
- All other movements felt solid and required a normal amount of stick input.
- Battery life was comparable to results I get near sea level. Definitely NO decrease in flight time.

Hope that can help some people out. I would definitely recommend the high altitude props if you are going to 8,000ft or above like the DJI rep suggested in the OP's post.

That's awesome, dude. Good job! THIS is the information I've been pining for. Since N.M. has many elevations, you can bet that I will keep those props with me for those time I've over 8,000' MSL.

I'm going skiing Sunday around 10K' MSL. If I have time, I will do some test flights!

D

 

[Donnie Frank]

I don't know for sure but;
Higher pitch props (1360) put more load on the battery and will give the sensation that the bird is more responsive in a climb. Also, maybe more quiet because lower RPM?

I live @ elevation 5200' MSL. So I think I'm in a grey area here. What I noticed was not much performance change. 8-10% MORE battery use. Much quieter.

 

[Donnie Frank]

I answered this back in March last year on another thread but the DJI 'tech' doesn't really answer the entire question or go into the risk of cavitation if the HA props are used at lower altitudes. Although true cavitation does not occur in air (since it's physical form cannot be altered like water) but stalling can occur because of the angle of attack of the propeller resulting in loss of thrust

I would definitely not use the HA props @ sea level. I can get away with using them @ 5200'-5500' MSL, but, as we all now know, they're designed for 8K' MSL and higher. Great thread.

 

[KyleIRYS]

There's a bit of fear-mongering on this post over the high altitude props. Everyone needs to stop thinking about them as special magical props only for use at high altitudes and all other applications you're doomed for destruction - they are simply props with greater pitch than the stock ones. For those who want to know what that actually means, either read below for a quick summary or spend some time researching online.

Greater pitch generally means higher total power output and lower efficiency at a given power output. The power output of the motors decreases with altitude as it does less work in thinner air, hence the reason they've been introduced to bump up the thrust. But for kit like Inspire's where you a very rarely changing payload by considerable amounts, the design spec props is exactly what you want aside from large changes in operating altitude. And efficiency wise, thinner air is less resistant air, so that may explain the comparative performance between sea level stock and high altitude.

All that said, they will defintiely work at sea level and the "danger" warnings people are posting are a bit mis-guided considering no one has actually provided any evidence so. Using them in thick air will increase the max power output of the system (read current draw leading to higher max thrust), so as long as the motors, ESC's and battery can handle the extra throughput you won't have issues there - you'll just see some differences in responsiveness, probably max speed and ascent/descent rate and as a worse case maybe even PID stability issues (although the Inspire's are tuned very well and it shouldn't make much difference). With limitted info supplied on all those components, I can't catagorically say it is all fine. But DJI has all those sorts of overload warnings and things built into DJI Go and as annoying as they are most of the time, if there were serious over-current issues it would be saying so.

And losing thrust (cavitation/stalling) on high pitch props is only a concern if you can't spin them fast enough. Can anyone provide what pitch the high altitude props are? A brief Google search came up with nothing. Stock are 15inch by 5inch. Because it would have to be a serious increase in pitch for the motors to not be able to push the props. I can't actually find any spec on the 3512 motors, but they don't appear to be spinning any slower than the Inspire 1 motors and so those issues are well beyond fruition at this point. A side note is the Inspire 1 props are 1345 to 1360 for high altitude, so enough to make a difference but certainly not enough to create the issues people are sugegsting on here.

 

[KyleIRYS]

With limitted info supplied on all those components, I can't catagorically say it is all fine. But DJI has all those sorts of overload warnings and things built into DJI Go and as annoying as they are most of the time, if there were serious over-current issues it would be saying so.

See the below thread for someone who has today supplied evidence of such alerts. It's an interesting error log and I'd be interested to hear if anyone else has had experience with it.
High altitude rotors at sea level