80mph+ with tail wind!

[Erised]

Yep air speed is the same it's just the ground speed that kick's A... 80 mph yepper been their done that too and a bit more! I did it the same way the OP did, I went for a quick flight before the storm came, it took almost 50% battery to get close and 18% to come back. I even had a barometer error because the pressure dropped so quick, my max altitude in my flight records showed over 5600 feet! but the craft remained at the same altitude(360). 5000 feet is only a 2 psi drop. Top speed that day was 89 mph, got home hand caught behind my garage, got in the house then the wind really blew hard about 5 minutes after I landed, I'm glad I was home before it hit. Man that was a hell of a ride! For the ones wondering how I was able the land(catch) it is that I live out in the country and as I came back home I dropped down lower in the field between my house and the tree line about 300 yards away. This little bird (P4) really impressed me that day, will I do that again? Well if the conditions are right I would like to at least break the 90 mph mark.

 

[Fly Dawg]

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.

Completely agree with that. My point being in that scenario, the structural stress that "could" be placed on said boat, could possibly exceed the design characteristics and cause unexpected ( And sometimes not visual) damage to said boat. A fast flowing river could be similar to high winds. There will always be unexpected turbulence in one form or another. This would be especially true for wind in or near a storm front or thunderstorm. Im not speaking of tornadic speeds for wind. That speaks for itself. I am speaking of updrafts, downdrafts and unexpected changes in wind direction while in flight. You could have a 40mph tail wind, as in this example, but a sudden updraft while in that tailwind would most likely exceed the design limits, and at that point as I mentioned, all bets are off. I completely understand where both you and @John Locke are coming from in your prospective.These were just my thoughts on it.

 

[lickitysplit11111]

Yep air speed is the same it's just the ground speed that kick's A... 80 mph yepper been their done that too and a bit more! I did it the same way the OP did, I went for a quick flight before the storm came, it took almost 50% battery to get close and 18% to come back. I even had a barometer error because the pressure dropped so quick, my max altitude in my flight records showed over 5600 feet! but the craft remained at the same altitude(360). 5000 feet is only a 2 psi drop. Top speed that day was 89 mph, got home hand caught behind my garage, got in the house then the wind really blew hard about 5 minutes after I landed, I'm glad I was home before it hit. Man that was a hell of a ride! For the ones wondering how I was able the land(catch) it is that I live out in the country and as I came back home I dropped down lower in the field between my house and the tree line about 300 yards away. This little bird (P4) really impressed me that day, will I do that again? Well if the conditions are right I would like to at least break the 90 mph mark.

Why couldn't you say 88mph instead of 89,
In Back to the Future, why was the speed 88 miles per hour?

 

[MaxHam]

Yep air speed is the same it's just the ground speed that kick's A... 80 mph yepper been their done that too and a bit more!

Are you guys sure you are not confusing mph with kmh?
According to Airdata my max speed with strong tailwinds in sports mode was 80.63 kmh.
I was never able to make it beyond that.
Could Atti be any faster than sports mode?

 

[Erised]

Are you guys sure you are not confusing mph with kmh?
According to Airdata my max speed with strong tailwinds in sports mode was 80.63 kmh.
I was never able to make it beyond that.
Could Atti be any faster than sports mode?

I think that if you let your craft drift in atti then fly exactly with the wind you should get to fly a bit faster as the craft wont compensate to keep a straight path. My top speed listed that in GO flight records wich at times seems to be over the actual, never the less my bird came home PDQ. I usually take off raise over 50 feet then switch to atti, take note of wind direction and speed then go in s mode cruising around 30 mph wich gives me the most distance for power consumption.

 

[Bakersfield Quad]

Common practice to take advantage of tail winds, saves fuel and time and cost nothing. Just make sure it is smooth, not rough, then you must reduce speed to avoid strain on the airframe.

 

[AWD]

Storm was bearing down and I was in front of it racing back. Grabbed a screen shot before calling it a night. It bumped 89 a few times but I couldn't get the screen capture at the right time.

AD

 

[Bakersfield Quad]

Storm was bearing down and I was in front of it racing back. Grabbed a screen shot before calling it a night. It bumped 89 a few times but I couldn't get the screen capture at the right time.

AD

Cool, nothing wrong with responsible playing around. I would be lying, if I said, I never pushed an aircraft to the edge, just always tried to stay on the sane edge.

 

[Russ43Phantom]

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.

As indicated in an earlier post, your drone experiences relative velocity so the stress into the wind or with the wind is not that much different. Where you might experience stress is from radical gusts causing rapid acceleration horizontally or vertically. Flying in these conditions is BOTH unsafe and unwise.

 

[Fly Dawg]

Where you might experience stress is from radical gusts causing rapid acceleration horizontally or vertically. Flying in these conditions is BOTH unsafe and unwise.

Is that not what I said earlier in this statement?

"You could have a 40mph tail wind, as in this example, but a sudden updraft while in that tailwind would most likely exceed the design limits, and at that point as I mentioned, all bets are off."

 

[Ty Alderdice]

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???

Wow! I had a slight tailwind with my P4 and in sport mode got 55 mph

 

[bkushner]

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???

Wow quite a feet. I've never managed to get past 65mph. For you to have a tailwind that gives you 80 mph the winds must have been brutal in which case I wouldn't fly!!!

 

[Riley Lake]

I'm an airline pilot by trade, so i get to see this all the time.

It is not that uncommon for the surface winds to be something like "light and variable" and then shear to 30 to 50 knots at 150+AGL.

Keep in mind that an aircraft flies in a "parcel of air", just as a boat or a leaf floats on the surface of the water. Also keep in mind that all motion is relative... imagine yourself standing still on a boat drifting down the river, and other than by looking at the a person standing along the shoreline, you perceive no motion. A person standing on the river bank also perceives no motion, other than by looking at the boat on the river.

The same analogy applies to an aircraft flying through the air, relative to the ground, except that the aircraft also has a 3rd possible direction of motion.

So, if an aircraft is flying in a parcel of air, it senses no motion of the parcel of air, just as the leaf or boat senses no motion of the water flowing down the river, even though the parcel of air may be moving 50mph, relative to the ground. That means that if the aircraft is capable of achieving an airspeed of 40mph, then it will only ever experience the forces of flight imposed on it generated by its movement through the air at 40mph. It does not matter that relative to the ground, it may be travelling at up to 90mph if it is moving in exactly the same direction as the parcel of air is moving... it is still only experiencing the forces of flight imposed by its speed of 40mph through the parcel of air. Since there is no physical connection from the ground to the aircraft or the aircraft to the ground, the motion of the ground relative to the aircraft, or the motion of the aircraft relative to the ground has no effect on the forces experienced by the aircraft. This is the fundamental difference between AIRSPEED and GROUNDSPEED.

The ultimate maximum speeds listed in the Phantom specs (top speeds in P and S modes) are AIRSPEEDS (speed relative to the parcel of air the Phantom is flying in) while the readouts we see on the display are GROUNDSPEEDS (speed of the Phantom relative to the surface of the Earth).

Some "Intelligent flight modes" may limit the aircraft speeds to a certain groundspeed, but the airspeeds that the aircraft will be experiencing will be higher or lower depending on the direction of flight relative to the ground relative to the direction of wind (parcel of air).

So, it is entirely possible that a Phantom could show a groundspeed of 88mph without exceeding or overstressing the aircraft or any of its components... save the pilot