Another fly-away: Can you help

[Count]

It seems the only time I write is when I have problems, and I do again. I have been doing some antenna combination testing, and doing some relatively high (for me) testing (yes I know the FAA ceiling is 400'). I usually fly at night over a golf course, so if (when) it comes down, it can cause no harm except to itself. I had several repeat trips up to 1200', and was working on extended distances out, and had NO issues. For fun, I decided to use 3 blade balanced graphite props for a change. It went up fine, but at about 50% battery, I decided to come down, and it would not descend, it seemed. Perhaps a foot per secend, and it was being blown by a 5-10 mph breeze away, and there was nothing I could do, yet I still had full video and control radio contact. The battery was discharging incredibly fast at seemed, and I was still over 1000 up and 1000+ away (it had drifted almost that much) when I decided to turn it off to invoke "go to home". It showed that it was engaged, but it was not returning. At about 10% battery I turned it on, flicked the right switch to the middle position (atti? I have not used it before), and I had FULL control, and started cooking towards home. Well, at about 3% and 400' up and out, the lights went out and it fell to the ground. Once I got the "find my Phantom" feature figured out, I was able to find it in the pitch dark and fortunately it did not go in the water.

So, can anyone suggest what may have happened? Why did I seem to get full control and response when I went into the Atti mode (again, I am not familiar with it). Could the 3 blade props have caused the situation (keeping in mind that I had flown virtually the same course previously that night with 2 blade graphite blades with no issues).

 

[ATOMSK]

That is impressive height. Did you ever try RTH? IF it was in GPS, I don't think it should have drifted that far. This is strange. Lets wait for someone else to answer.

 

[IrishSights]

Technical analysis will have to wait for someone more knowledgeable than me. My first comment would be that you were pretty well pushing the envelope of normal generally recognised operating parameters. At 1000' at 2m/s thats around 4 min to get down plus the added time to come back from 1000' out and only 50% battery just isn't enough in my opinion.

If it was drifting and in GPS mode the only explaination is that the winds at 1000' were stronger than the phantom could beat. You then had the added complication that you were flying at night. Just my input.

 

[N017RW]

This was not a fly-away.

 

[IrishSights]

Another thought on re reading your OP...I seem to remember reading that 3 blade props had odd flight characteristics with a Phantom. Did you research it first? I think there is just to many risks here to lay at any other feet other than the pilots decision making process. No poke intended, just being honest.

Added edit: if you have as you stated no experience of ATTI mode and being this adventurous then it is one risk too many that caused the crash. - agreed - not a flyaway

 

[ProfessorStein]

The fact that you say it "didn't want to come down", that it was "being blown", and that it's battery was discharging so fast, I'd say that the Phantom was overwhelmed by the wind. You say it was a 5-10 mph breeze, but, in fact, you have no idea how strong the wind was at 1000'. It's a good bet that it was a great deal stronger. Winds will typically get stronger at higher altitudes, as I'm sure you're aware. What is a 5 mph breeze at ground level can be upwards of 20-30 mph or more at 1000' under the right conditions.

In short, it sounds like your Phantom was simply taken, like a sail, by the gusts it was riding on. There are several videos around of pilots suffering from the same fate as yourself.
https://www.youtube.com/watch?v=GfxdeRx2fLA




BTW, ATTI mode is only available if you have switched your Phantom to NAZA mode using the Assistant utility. Have you done so? Even if you did, ATTI might not have helped all that much in this situation. With it's steeper attack angles, it may have been able to fight against the wind laterally, but it wouldn't have done anything to help with descent.

 

[ProfessorStein]

Another thought on re reading your OP...I seem to remember reading that 3 blade props had odd flight characteristics with a Phantom.

Indeed, in this situation, 3-bladed props would've just added more plastic/surface area for the wind to push up against. More "sail", as it were.

 

[Damon]

Edit ( reading page wrong)

Probably only two ways out of this mess. CSC to drop free fall and hope to CSC half way down to fire motors back up or program S1 bottom to Manual. Descent in Manual is **** close to motors off descent. Not a fan of either unless I had a bunch of money to piss away...

 

[Damon]

 

[Damon]

Oops. Read wrong 2 1/2 minutes. Duh..

 

[Count]

Thanks for your responses. I did not realize I was pushing the envelope height wise, given that I regularly read of people flying 2000+ feet away, distance wise. Is there a difference between height and distance? My logic tells me no but I am not an engineer... I said I went into Atti mode, but that was what I thought I was doing. I switched the right switch down to the middle position, and I regained full control. Sorry if I used that term incorrectly. I will have to agree that I did not consider upper level breezes (winds) and that certainly could have been my issue. I am close to being rebuilt, and will try it again with original props, and see what happens. As always, thanks...

 

[ProfessorStein]

I did not realize I was pushing the envelope height wise, given that I regularly read of people flying 2000+ feet away, distance wise. Is there a difference between height and distance?

Technically, no... the hypotenuse is the same. But realistically, yes. If you're 2000' away, but only 50' up, you're going to be in manageable and predictable winds (ie - conditions are going to be pretty similar to what you're experiencing at your piloting location). If you're 50' away, and 2000' up, you're going to be in lighter, colder air with no idea about wind conditions.

 

[Damon]

Thanks for your responses. I did not realize I was pushing the envelope height wise, given that I regularly read of people flying 2000+ feet away, distance wise. Is there a difference between height and distance? My logic tells me no but I am not an engineer... I said I went into Atti mode, but that was what I thought I was doing. I switched the right switch down to the middle position, and I regained full control. Sorry if I used that term incorrectly. I will have to agree that I did not consider upper level breezes (winds) and that certainly could have been my issue. I am close to being rebuilt, and will try it again with original props, and see what happens. As always, thanks...

Covering a distance of 2000+ is not a huge deal because the speed horizontally in GPS and ATTI is nothing compared to speed limit of descent.

Just an example is in ATTI you can easily travel 20+ meters a second horizontally. However, in ATTI mode you can only descend 2 meters a second MAX.

 

[yali]

It seems the only time I write is when I have problems, and I do again. I have been doing some antenna combination testing, and doing some relatively high (for me) testing (yes I know the FAA ceiling is 400'). I usually fly at night over a golf course, so if (when) it comes down, it can cause no harm except to itself. I had several repeat trips up to 1200', and was working on extended distances out, and had NO issues. For fun, I decided to use 3 blade balanced graphite props for a change. It went up fine, but at about 50% battery, I decided to come down, and it would not descend, it seemed. Perhaps a foot per secend, and it was being blown by a 5-10 mph breeze away, and there was nothing I could do, yet I still had full video and control radio contact. The battery was discharging incredibly fast at seemed, and I was still over 1000 up and 1000+ away (it had drifted almost that much) when I decided to turn it off to invoke "go to home". It showed that it was engaged, but it was not returning. At about 10% battery I turned it on, flicked the right switch to the middle position (atti? I have not used it before), and I had FULL control, and started cooking towards home. Well, at about 3% and 400' up and out, the lights went out and it fell to the ground. Once I got the "find my Phantom" feature figured out, I was able to find it in the pitch dark and fortunately it did not go in the water.

So, can anyone suggest what may have happened? Why did I seem to get full control and response when I went into the Atti mode (again, I am not familiar with it). Could the 3 blade props have caused the situation (keeping in mind that I had flown virtually the same course previously that night with 2 blade graphite blades with no issues).

The Reason is the wind at that height is too much for the vision to handle. That simple. The higher, the stronger the wind! that's a common knowledge!

 

[RCRookie]

Thanks for your responses. I did not realize I was pushing the envelope height wise, given that I regularly read of people flying 2000+ feet away, distance wise. Is there a difference between height and distance? My logic tells me no but I am not an engineer... I said I went into Atti mode, but that was what I thought I was doing. I switched the right switch down to the middle position, and I regained full control. Sorry if I used that term incorrectly. I will have to agree that I did not consider upper level breezes (winds) and that certainly could have been my issue. I am close to being rebuilt, and will try it again with original props, and see what happens. As always, thanks...

There is a difference as far as the revision is concerned. The Vision assistant sets "altitude" limits different from distance limits (see assistant parameters) If i understand right... You can set distance above the limits in the software, but the same is not true for altitude.