Altitude not holding when over 35mph

Dunginhawk · Jul 27, 2015

make sure you make it a long enough run to build up that speed, but i guess you did to get it to 39. I am just buzzing along and just hit that perfect spot and BAM starts dropping like crazy, but not until it hits that point of no return.

Jubalr · Jul 27, 2015

OK. Went out on some evening speed runs and found the magic bullet! As I suspected, it does not have to do with speed but is much more dependent on AOA/pitch angle (angle of attack). I have been flying around with my performance settings at 3/4 of the way up. This allows for a top speed of 40mph but at a much less pitch angle, or about 25-27deg nose down. It takes a few seconds longer to get to 40, but it does. When I turned the performance sliders all the way up, my available top speed was greater but even worse my pitch down went to 35deg nose down. It started dropping fast by the time my speed was in the low 30s. I forgot to try a run with throttle compensation but will the next time out. That will show whether the pitch down is too great for the power/pitch of the props or it is just hitting the compensation limits set in the parameters. As far as the spec top speed of 55, I have seen videos of pilots doing that and faster but usually in sport and acro.

For the doubters, the 2 videos below will show graphically what is happening and leave little room for other explanations. This is strictly flight physics and applies to all full size aircraft as well (fixed and rotor).

The first video is with the performance sliders at 3/4. The 2nd video is at full performance.

rrmccabe · Jul 27, 2015

Thanks for doing that. But to fly the rated 55mph you need the angle of attack. The props cant spin fast enough to increase speed to 55 without it right?

Dunginhawk · Jul 27, 2015

jubalr, i am totally with you here, as I took my solo out tonight and easily replicated it, but only IN to the wind. With the wind pushing down, along with the pitch it was too far down and caused it to drop like a stone, even though i was only doing 30 mph.
Was going over 50mph in the other direction with very little drop in altitude.

So yeah. im ok with the explanation given, but that does not absolve 3dr either. They need to make GPS mode at least fail proof from this respect. Whether that is limiting things further, or whatever with sliders, I just know whats going to happen "BUT I WAS IN GPS MODE" and they are right. GPS is beginner mode and under no circumstances should it diving that quickly (and it is possible in gps mode).

Im not happy either way

Jubalr · Jul 27, 2015

rrmccabe said:
Thanks for doing that. But to fly the rated 55mph you need the angle of attack. The props cant spin fast enough to increase speed to 55 without it right?

It's going to be a sweet spot of AOA and power applied. A really good pilot that knows where the max AOA to power ratio is and managed the run when all conditions were perfect. That's why that it is stated as Max speed in the specs. It's kind of like other products specs that were achieved in a lab and difficult to reproduce but still technically correct. I have not tried a max speed test but will next time out. It's not something that is important to me. I really don't have a need to go over 40 in my use.

Jubalr · Jul 27, 2015

Dunginhawk said:
jubalr, i am totally with you here, as I took my solo out tonight and easily replicated it, but only IN to the wind. With the wind pushing down, along with the pitch it was too far down and caused it to drop like a stone, even though i was only doing 30 mph.
Was going over 50mph in the other direction with very little drop in altitude.

So yeah. im ok with the explanation given, but that does not absolve 3dr either. They need to make GPS mode at least fail proof from this respect. Whether that is limiting things further, or whatever with sliders, I just know whats going to happen "BUT I WAS IN GPS MODE" and they are right. GPS is beginner mode and under no circumstances should it diving that quickly (and it is possible in gps mode).

Im not happy either way

Sure D, understood. But what does GPS mode have to do with it? Like manual, max performance will be in non GPS modes. I rarely fly in 'Fly' or loiter, but know the speed is much lower.

Dunginhawk · Jul 27, 2015

Because i achieve this high AOA in gps mode... but.... i may have modified my params haha

rrmccabe · Jul 27, 2015

Jubalr said:
It's going to be a sweet spot of AOA and power applied. A really good pilot that knows where the max AOA to power ratio is and managed the run when all conditions were perfect. That's why that it is stated as Max speed in the specs. It's kind of like other products specs that were achieved in a lab and difficult to reproduce but still technically correct. I have not tried a max speed test but will next time out. It's not something that is important to me. I really don't have a need to go over 40 in my use.

Not going along with you on this. 3dr rated solo at 55 mph in alt hold mode. Period.

Anything thing else is like rating the terminal velocity of a rock.

It's basically useless. I can't fly 15 seconds without letting off or flying it into the ground.

Dunginhawk · Jul 27, 2015

Right, and thats been my argument all along... Yes, it takes pilot skill to manage things on a quad, and its common sense that if you hit that point and its nosing down you have to compensate.
But the problem is, once again, if you are going to sell a quad that you claim hits 55mph in a mode that should have alt hold assigned to it, then do it. otherwise its just another missed promise.
I wish it could maintain that speed without killing my neighbors dog

David Weston · Jul 28, 2015

OK, I probably should keep my mouth shut but,,,Max performance is stated by almost all manufacturers (for instance Corvette) under ideal circumstances. Acceleration, braking distance horsepower, etc. Individual experiences will vary. I know what the argument is but, IF, the max speed is 55mph, which I don't know as I have never tried it, but if it is then I would say it was a true statement. How or where one decides to try to get max speed is another story. My butt has a lot of hours sitting in the cockpit of a helo and I can tell you what "max air speed" is and you just don't :floor it" and not expect some pretty challenging dynamics, not to mention the avionics and control systems make PIXHAWK like, well, what it is, and RC hobby. So my friends, and you are my friends, my rebuttal is "Max speed is at the pilots discretion" just as max speed in a Corvette is at a driver's discretion. It's not for everyone under all conditions. We are all entitled to our opinions and this is just mine.

Jubalr · Jul 28, 2015

rrmccabe said:
Not going along with you on this. 3dr rated solo at 55 mph in alt hold mode. Period.

Anything thing else is like rating the terminal velocity of a rock.

It's basically useless. I can't fly 15 seconds without letting off or flying it into the ground.

OK. understood. I didn't see in the specs where they specified 'alt hold'. Just max speed 55. But that again will be ideal conditions and the right pilot. It's like a gun manufacturer stating that the rifle is capable of a 4" group at 1000 yards. I doubt I could do it without a lot of practice. Or the claimed talk and screen on time of my phone. etc.. But I know you are disappointed in a lot of things about the Solo and expect you will be taking advantage of the return policy. I wish it had worked out better for you.
Here is a 54mph run..in manual mode and just above some trees.

Raybro · Jul 28, 2015

Jubalr said:
OK. understood. I didn't see in the specs where they specified 'alt hold'. Just max speed 55. But that again will be ideal conditions and the right pilot. It's like a gun manufacturer stating that the rifle is capable of a 4" group at 1000 yards. I doubt I could do it without a lot of practice. Or the claimed talk and screen on time of my phone. etc.. But I know you are disappointed in a lot of things about the Solo and expect you will be taking advantage of the return policy. I wish it had worked out better for you.
Here is a 54mph run..in manual mode and just above some trees.

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What kind of a setup do you have on your Solo? Top mounted camera, speed, track overlayed in video.

Jubalr · Jul 28, 2015

Raybro said:
What kind of a setup do you have on your Solo? Top mounted camera, speed, track overlayed in video.

Not sure what you are referring to. The Solo is bone stock. If you are talking about the videos I did above, those were just done in MP with screen recording software playing back the logs I emailed to myself. The video of the pilot doing 54 was not me.

Raybro · Jul 28, 2015

Jubalr said:
Not sure what you are referring to. The Solo is bone stock. If you are talking about the videos I did above, those were just done in MP with screen recording software playing back the logs I emailed to myself. The video of the pilot doing 54 was not me.

I see. Nice, I didn't know it would do that. It looks like the camera is mounted on top of the Solo. I need to play around with MP. Don't have a lot of time like some of you. Gotta work to pay for all this stuff.

rrmccabe · Jul 28, 2015

Jubalr said:
OK. understood. I didn't see in the specs where they specified 'alt hold'. Just max speed 55. But that again will be ideal conditions and the right pilot. It's like a gun manufacturer stating that the rifle is capable of a 4" group at 1000 yards. I doubt I could do it without a lot of practice. Or the claimed talk and screen on time of my phone. etc.. But I know you are disappointed in a lot of things about the Solo and expect you will be taking advantage of the return policy. I wish it had worked out better for you.
Here is a 54mph run..in manual mode and just above some trees.

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For more detailed information, see our cookies page.

Well the specs original said manual mode. not "alt hold". The manual has changed 3 times in this regard and at one time contradicted itself front of manual to the specs in back. I think now it says advanced modes in both spots. I actually called them on it and they said they would fix the manual.

Colin was a little deceiving about the entire deal speaking about how it flew 55mph as if the white one could not do that. Actually I would be surprised if the white one would not fly 55 in full manual in a dive. Never had the guts to try it.

Doesn't matter. Colin has a little used car salesman in him

I think Ray was talking about seeing spinning props in video.

Was not aware MP would do any overlay on video like Dashware.

Raybro · Jul 28, 2015

Jubalr said:
Not sure what you are referring to. The Solo is bone stock. If you are talking about the videos I did above, those were just done in MP with screen recording software playing back the logs I emailed to myself. The video of the pilot doing 54 was not me.

I've got a lot to learn about the 3DR software. When the Solo was announced I was frequently on the DJI forum with my P2. Several of the more experienced people there really talked up the PixHawk controller and it was there that I would decide to go with 3DR. I'm glad you are on this forum to help us newbies out with this stuff.
Ray

Jubalr · Jul 28, 2015

rrmccabe said:
Well the specs original said manual mode. not "alt hold". The manual has changed 3 times in this regard and at one time contradicted itself front of manual to the specs in back. I think now it says advanced modes in both spots. I actually called them on it and they said they would fix the manual.

Colin was a little deceiving about the entire deal speaking about how it flew 55mph as if the white one could not do that. Actually I would be surprised if the white one would not fly 55 in full manual in a dive. Never had the guts to try it.

Doesn't matter. Colin has a little used car salesman in him

I think Ray was talking about seeing spinning props in video.

Was not aware MP would do any overlay on video like Dashware.

Yeah, I think Colin was hired for his salesmanship! No doubt. But at least we have seen 54 in manual. Now I'll see if I can get that last 1mph. I hope I have scratched 2 complaints off your list so you can keep the Solo when (if) we get the gimbal. I haven't seen the screen flicker, so can't test that myself. Hopefully it has to do with the POS HDMI connection they are using now.

David Weston · Jul 28, 2015

Rich, I think the manual was printed by the NYT so it's OK..lol

rrmccabe · Jul 28, 2015

Jubalr said:
Yeah, I think Colin was hired for his salesmanship! No doubt. But at least we have seen 54 in manual. Now I'll see if I can get that last 1mph. I hope I have scratched 2 complaints off your list so you can keep the Solo when (if) we get the gimbal. I haven't seen the screen flicker, so can't test that myself. Hopefully it has to do with the POS HDMI connection they are using now.

Which complaints off my list? I am not sure it has resolved anything for me as they are still issues as far as I am concerned.

As far as gimbal, I think I am going to leave that to you boys to figure out.

Jubalr · Jul 28, 2015

rrmccabe said:
Which complaints off my list? I am not sure it has resolved anything for me as they are still issues as far as I am concerned.

As far as gimbal, I think I am going to leave that to you boys to figure out.

The top speed and altitude not holding.
Sure hate to see you give up on the Solo, but totally understand given the issues you have had from day one.
Take care and Fly Safe..
Jubal