80mph+ with tail wind!

[AirMan05446]

What a rush. Was getting in some flight time before the storm rolls in. Wind was getting pretty strong so I wanted to see what a tail wind did speed-wise.

Holy moly! I had it up over 80mph in ATTI mode when the angle was *just* right. Of course between that and then coming back against the wind it killed the battery pretty quickly.

Anyone break 100mph???

 

[Fly Dawg]

You were asking for trouble there my friend. I would really look closely for stress cracks from flying at that speed, even if the wind was carrying it. It might even be considered "reckless". But, that said, I would take that speed reading with a huge grain of salt. I am guessing you pulled that from the logs. A bit much for for me, although I have had her up in an approaching storm, but landed well before arrival of storm frontal boundaries. Those can get really unpredictable. And in fact could pull the Phantom in the updraft, never to be seen again.

 

[SRJ_Phantom_4_Pro]

Photo evidence or it never happen.....

 

[Blinky]

I'm with SRJ_Phantom_4_Pro.........

 

[lickitysplit11111]

Photo evidence or it never happen.....

Thats what im talkin bout....

 

[Fly Dawg]

After reading back what I posted, it really does not make any difference which Aircraft. Those numbers are unrealistic at best. And as SRJ_Phantom_4_Pro mentioned, I will say that Photo evidence would be useless in determining the actual speed of the aircraft.

 

[Meta4]

You were asking for trouble there my friend. I would really look closely for stress cracks from flying at that speed, even if the wind was carrying it. It might even be considered "reckless". But, that said, I would take that speed reading with a huge grain of salt. I am guessing you pulled that from the logs. A bit much for for me, although I have had her up in an approaching storm, but landed well before arrival of storm frontal boundaries. Those can get really unpredictable. And in fact could pull the Phantom in the updraft, never to be seen again.

Speed has nothing to do with developing cracks at all and everything to do with having a weak shell to begin with.
And when travelling in air that's moving, the Phantom doesn't feel any additional strain due to the speed that air mass is moving.
It's like walking on a moving walkway.
If the speed was from the logs, it's generated by GPS and will be accurate.
The biggest worry was that he went away with the wind and had to fight it coming home.
That's an unsafe practice and can be a good way to lose a drone.

 

[AirMan05446]

Not going by logs, going by the read-out (HS). So do you guys think the indicated HS was off?

Next time I get a good tailwind I'll do a set distance and time it and see and will update this thread.

 

[Fly Dawg]

Speed has nothing to do with developing cracks at all and everything to do with having a weak shell to begin with.
And when travelling in air that's moving, the Phantom doesn't feel any additional strain due to the speed that air mass is moving.

I agree, a weak shell would be a major factor, however, depending on the direction of travel, speed and wind direction, any aircraft will have issues, unless they are specifically designed for such forces that may be applied to the aircraft frame. I don't think the Phantoms were designed for such stress in the instance being reported here. Please correct me if I am wrong in that assessment.

 

[AirMan05446]

The biggest worry was that he went away with the wind and had to fight it coming home.
That's an unsafe practice and can be a good way to lose a drone.

Good point for beginners, but this was all done with VLOS and for short distances. I had over 50% battery when I landed.

I gotta say I'm shocked at the nannies here.It was short duration speed bursts 300 feet up in an open field and some of you have make it sound like I was barnstorming.

 

[Fly Dawg]

I gotta say I'm shocked at the nannies here.It was short duration speed bursts 300 feet up in an open field and some of you have make it sound like I was barnstorming.

That is exactly how you made it sound. Had you given a bit more information it could have been better explained.

 

[Fly Dawg]

I gotta say I'm shocked at the nannies here.

In response to that, I would just say that it's not as you say "nannies" around here. We all want to work together to help each other as best we can. Constructive criticism is a good thing for all involved. I have no issues being proven wrong in things I say. That's how you learn. Take that and let it soak in. And don't take things to heart.

 

[lickitysplit11111]

Good point for beginners, but this was all done with VLOS and for short distances. I had over 50% battery when I landed.

I gotta say I'm shocked at the nannies here.It was short duration speed bursts 300 feet up in an open field and some of you have make it sound like I was barnstorming.

Err, I'm not really sure how this works but if it only flys at 45 mph how strong a tail wind would it take to push it along at 80 mph, and in as little as 45 seconds you'd be a mile away , No ?
Was it really windy on the ground when launching ?

 

[Fly Dawg]

Err, I'm not really sure how this works but if it only flys at 45 mph how strong a tail wind would it take to push it along at 80 mph, and in as little as 45 seconds you'd be a mile , No ?

Good point. It would be more like 5-10 seconds in the scenario as given. And at that you would have to be flying with the wind at top speed to be overtaken by the wind to get to that speed. Bizzare and seemingly impossible.

 

[SRJ_Phantom_4_Pro]

Which is why I asked for some sort of proof to back up that claim.... Otherwise it's yet another internet fable....

 

[John Locke]

With the right wind, say 35mph, I can easily believe 80mph in ATTI. That's a pretty good wind, so it would be wise to fly upwind about 2000' to make a good pass and end the speed run nearby. This scenario would be little risk, except when you land. You can't land on the ground in that kind of winds and not ruin a prop or two, maybe harm the camera too. It will almost certainly flip in that kind of wind upon landing, unless you can find a windbreak, like a wall to land behind. I've hand caught my craft in 30-35mph wind and it was spooky. This wind came up in a matter of minutes, going from ~10mph to 30-35mph really fast in the Santa Ana Canyon in So. Calif, known for the "Santa Ana Winds" that blow from the desert out to the ocean during the winter. I really don't want to do it again, but I managed to catch it pretty safely in that gale of a wind.

I will often switch my P4P into ATTI when I suspect wind at altitude, just to measure the wind speed with no stick input. It only takes about 15 seconds to see the speed "top out" in the drift with the wind. I did that last weekend along the Calif coastline, near Pismo Beach. I knew I was flying downwind, so I needed to gauge when to turn around to have enough battery. Floating with the wind in ATTI is the best way to make that math calculation, using my P4P top speed of 40mph in S mode as a conservative "top speed" number. 40mph minus wind speed = relative speed to home. Then calculate time needed by dividing the speed into distance needed to get home. 12mph= .2mi/min or 18mph = .3mi/min or 24mph = .4mi/min, etc.

So if I'm downwind 1 mile away, and there's a 28mph wind, it's going to take me ~5 minutes to get back to home in S mode. Gotta be careful in this scenario because wind speeds can change, pretty quick.

 

[Meta4]

I agree, a weak shell would be a major factor, however, depending on the direction of travel, speed and wind direction, any aircraft will have issues, unless they are specifically designed for such forces that may be applied to the aircraft frame. I don't think the Phantoms were designed for such stress in the instance being reported here. Please correct me if I am wrong in that assessment.

Almost all Phantoms never develop any cracking and just a few do.
Those that do will crack even without any hot dog flying.
The Phantom shell is very strong and can't fly any faster than it's been designed.
Hitching a ride on a tailwind might make for impressive sounding numbers (over the ground) but the the Phantom isn't going any faster or subjected to any stresses above what it's designed for.

 

[Fly Dawg]

Hitching a ride on a tailwind might make for impressive sounding numbers (over the ground) but the the Phantom isn't going any faster or subjected to any stresses above what it's designed for.

This part I disagree, design wise. Per the Phantom Specifications are specific numbers. Those numbers, generally speaking are on the top end maximums. Any credible designer will tell you that you do put those numbers in prospective. You give a maximum specification and add a percentage to that number. But if those extra percentages are exceeded, all bets are off. Bottom line it's aero stress, beyond the design limits. It may do nothing once. But if it occurs more often....well then you know.

 

[John Locke]

Bottom line it's aero stress, beyond the design limits. It may do nothing once. But if it occurs more often....well then you know.

Huh?

 

[Meta4]

This part I disagree, design wise. Per the Phantom Specifications are specific numbers. Those numbers, generally speaking are on the top end maximums. Any credible designer will tell you that you do put those numbers in prospective. You give a maximum specification and add a percentage to that number. But if those extra percentages are exceeded, all bets are off. Bottom line it's aero stress, beyond the design limits. It may do nothing once. But if it occurs more often....well then you know.

Imagine rowing a boat downstream in a fast flowing river.
That's the effect.
You get to go fast over the ground but you aren't wearing yourself or the boat out.
It's mph for free.