1 (edited by heynewt 11-22-2011 00:37:43)

Topic: After-Crash - what I wish I had known (also tips for stable flying)

Just a couple of tips for Drone noobs I learned the hard way.

[edit nov 19, 2011] - wanted to put this high on the post.  Terrific site with way more good information about Drones than this little post.  Go there read it.  Read it again.  Good info, well laid out.  http://www.dronescapes.com/

Got my repaired AR Drone back the other day (great job with the repair, Parrot, thanks).  I did what I think everyone does when they first open the box.  I watched a couple of the videos and started flying immediately.  Since I was an experienced RC airplane pilot, I thought I wouldn't need to get up to speed on the AR Drone.  I was wrong.

First briefly, my crash was caused by sheer stupidity.  It was cold outside (battery drains faster) and the Drone was about 60 feet in the air when the low-battery warning came on.  I didn't land immediately and it did the emergency cutout.  Dropped like a rock to the pavement.  THe landing gear cracked at the center intersection, but I didn't notice.  Tried to fly it later inside and it was erratic as hell, crashed it hard against a wall and that damaged the mobo.  After that i just sent it in.

Ok, had it back for a week, flown every day and done what I should have done in the beginning, I've carefully "studied" how this thing works.  Here are 3 quick tips for those who don't want to read the following long post:

1. FLAT TRIM.  Always.   Before EVERY flight.  And in the your first day or so reduce your tilt angle to 5deg.  You'll thank me.

2. Unplug Reset.  Unplug Reset. Unplug Reset.  Do it all the time, especially after a crash.  I'm not talking about the reset button on the bottom.  For some reason I've found that doesn't do enough to clear the memory.  I unplug reset after every 3 flights, because I found that the more you take it off without resetting the more erratic it flies on each consecutive flight.

3. Indoors and outdoors, but especially indoors, make sure there is a big high-contrast pattern underneath the Drone before you take off.  Carpet is NOT a high-contrast pattern.  The Drone uses motion tracking with its underside camera to stabilize its X-Z position in space.  It uses the on-board altimeter to stabilize its Y position, but that underside camera is too low-rez to track the pattern of a carpet.  That's why you see people taking off from the box.  They didn't make that "H" landing pad on the box to be cool, they made it, because it's the perfect pattern for the underside camera to see.  This is very important to keep the Drone from drifting around the room over a carpet.  In lieu of the box, take black tape and put a crosshair or just black strips here and there.  It's that important.

Ok, now I'll go into a little more detail about flying the drone.   You can't compare this to an RC Helicopter, it's not.  It's a flying computer.  It has Artificial Intelligence, it senses its environment and reacts to that environment.  It's also incredibly well constructed.  I don't think you can damage it at all in an empty carpeted room with 8ft ceilings no matter what happens.   That fact alone makes it worth the nearly $300.  There must have been a LOT of R&D crashes to get something light enough yet tough enough to handle a lot of crashes without any damage.  The blades are really tough and flexible as is the landing gear.  They don't shatter like normal RC planes or helicopters. 

Please make your first flights indoors in a room that you've cleared out as much of the furniture as you can.  Don't go outdoors for the first flights.  Use default settings and then reduce the tilt (not the iPhone tilt, but the Drone tilt) to 5deg for indoors.  I have no idea why the default for indoors is not the minimum 5deg. 

On your first takeoffs just take it off, let it stabilize and land it.  Letting it stabililize after takeoff is VERY IMPORTANT.  Don't start flying it immediately.  The manual says 10 sec.  I say about 5 or 6, but the A.I. needs to evaluate the environment and get ready for your input.  Get a feel for how that process goes.  It's ever-so-slightly different on each takeoff so it's important that you get comfortable with pushing that takeoff and landing button and seeing what happens.  Next do only elevation changes with the right control button.  Take it up, take it down.  Take it up, push land.  Then take it up to the ceiling.  Wait, look what happens when it gets near ceilings.  Bang, it kind of goes out of control and hits the ceiling.  Not sure why that happens, but it does.  So you've learned an important lesson.  DON'T FLY CLOSE TO A CEILING, it's not stable near ceilings.

Also, the videos show the Drones flying down hallways.  I tried flying it down a narrow hallway and it started bouncing off the walls.  Personally I think the same programming that makes it freak out at ceilings makes it freak out in narrow hallways.  It likes open space.  But I'm happy for someone to correct me on this point.  Maybe I'm doing something wrong.

When you first go outside keep the indoor hull on for the first several flights.  The perfect flying environment for outside flight is a wide flat field, no wind, with tall grass for cushion.  The Drone is always "pinging" the ground with high frequency sonar to determine its height.  So if you're flying over stairs or a section of split-level ground the Drone will follow the contour of the stairs/ground.  For instance if you fly it over an 8ft retaining wall the Drone will plunge 8ft but not crash into the ground below.  Try it, it's actually cool after you get your heart beating again.

The Default settings work well outside as long as you uncheck "Altitude Limited" and check "Outdoor Flight".   If you're an experienced RC pilot you know that wind is your obsession.  I flew RC ultralights and I couldn't fly over 4knots of wind.  The AR Drone does not sense wind, but it does sense drift of the aircraft by the underside camera looking at patterns below it.  So if the wind is pushing it sideways it says, hmmm, the user is not making me go sideways, why am I going sideways must be the wind, I'll tilt myself in the opposite direction until I stop drifting.  That is freaking amazing!  Watching it compensate for wind is worth the $300 in my book.

Ok, one of your first temptations outside is to turn the Drone around so that the camera is photographing you, the pilot, get some cool video of yourself.  That's fine to do, but if you haven't flown RC planes before you have to get your mind around the fact that the controls are suddenly BACKWARDS, because it's facing you.  Try to resist that temptation at first, because your corrections, especially as you get nervous are all going to make the Drone move opposite of what you want, and it ends up snowballing into a bad crashy.  Hence why you don't take off the indoor hull for a while even outdoors.   

I recommend always flying with the drone pointing in the direction of your body and just use the iPhone to move it back and forth left and right.  If you turn the Drone, move your body behind it so the controls remain natural.

Get used to pressing the "Land" button to get the Drone down, even if your landing site is not perfect.  Once you press that button you lose control of the Drone, but the A.I. on board is actually better than you are at making a safe landing.

When you get really good (and it takes a long time) you can fly it like an airplane by coordinating the yaw and the bank so that it's always looking forward and performing graceful turns like a plane.  You rarely see that in videos, because it takes that much skill.

I use "FlightRecord" to get video from the Drone.  I also use a 3Gs.  On a 3Gs the video rate is probably 10fps, and when you're recording video the CPU overhead is pretty high, so the Drone is sluggish and control latency is high.  I switched to my wife's 4g iPhone and video recording was like 18fps.  Bottom line is, the faster the iPhone/iPad, the better the video.  But I can't find any difference with the FreeFlight application between phones.  Same response times.

Finally, NEVER CHARGE THE BATTS RIGHT AFTER FLYING.  They may only feel warm, but lil-poly batts like to be as cold as possible before charging.  Wait 15 minutes at least, they cool down pretty fast.

These tips are not intended to cover all aspects of flying, but just to keep you from crashing your new flying computer.

My last thoughts are this:  It's BRILLIANT that Parrot made the iPhone software open-source.  AR Pursuit is the first of cool software, and there's going to be a lot more.  As phones get faster the apps are going to get cooler.  But now I'm going to have to fly it with an iPad.  Sigh.

One last thing.  There's a great RC Groups forum for people who want to mod their Drone and get some incredibly detailed info on it.
http://www.rcgroups.com/forums/showthread.php?t=1335257

Enjoy your flying, it's a very cool little gadget.

Re: After-Crash - what I wish I had known (also tips for stable flying)

Well done!!!  This should be mandatory reading for any new Drone owner!

Re: After-Crash - what I wish I had known (also tips for stable flying)

Well done.

This is what Parrot should tell in the flight lessons.

Regards.

Alan

Re: After-Crash - what I wish I had known (also tips for stable flying)

Excellent write up - thanks!

Re: After-Crash - what I wish I had known (also tips for stable flying)

heynewt wrote:

Also, the videos show the Drones flying down hallways.  I tried flying it down a narrow hallway and it started bouncing off the walls.  Personally I think the same programming that makes it freak out at ceilings makes it freak out in narrow hallways.  It likes open space.  But I'm happy for someone to correct me on this point.  Maybe I'm doing something wrong.

Heynewt,

I really appreciate your post, this should come with every new AR Drone in a 'read before first flight' (or rather: read during your first battery charge cycle) package !

On the point of instability, I may be able to help you out. It's not programming causing this, but plain aerodynamics.

Since the propellors are blowing down, air pressure under the drone is higher than average, and air pressure above the drone is lower than average. This pressure difference creates the lift that holds the drone in the air. Fly close to the ground and you will see the drone behave unstable, as the air from the propellors can only flow sideways instead of down. A small tilt of the drone will make this flow asymmetric and cause instability.

Fly close to a ceiling and you will see the drone suck itself to it. Air can now only flow towards the propellors from the side and no longer from above, so the pressure above the drone drops even further. The 'vacuum' that is created gets stronger as the gap between the drone and the ceiling gets smaller, since less air can flow in from the sides. Try it yourself by holding your hand close to the mouth of a vacuumcleaner and close the gap slowly: the closer you get, the harder it sucks.

The same aerodynamics explain the bumpy behavior when you're close to a wall. In normal flight, air will circulate from the bottom (overpressure) to the top (underpressure). This flow will create additional lift on the edges of the indoor hull - it is simply 'blown upwards' by its own circulation. If you get close to a wall, that circulation is cut off by the wall. This will reduce the lift on that side, making the drone tilt towards the wall and bump into it.

Safe to say (I quote you once more): it likes open space !

Re: After-Crash - what I wish I had known (also tips for stable flying)

I never thought about the fact that the Drone is basically trying to suck itself onto the ceiling.  That makes total sense!  Really appreciate that clear explanation of the aerodynamics of the Drone.  And your post is a good addendum to mine.  Another must-read.

I'd love to hear more about airflow around the Drone.  The more I fly, the more I realize there's just a crapload of stuff going on with that little aircraft, stuff I don't even realize.

Re: After-Crash - what I wish I had known (also tips for stable flying)

Great post! Thanks!

One question only: what do you mean by "2. Unplug Reset.  Unplug Reset. Unplug Reset. "?

8 (edited by heynewt 01-10-2011 22:51:36)

Re: After-Crash - what I wish I had known (also tips for stable flying)

Hi,

I just meant to get in the habit of resetting by unplugging the battery for a few seconds rather than pushing the "reset" button on the bottom.  I'm not saying the "reset" button doesn't do its job most of the time, I'm saying just to be safe, you can't go wrong by a full reboot of the system, especially after a crash or any kind of error message.  Yes, it's a pain, but it's less of a pain than repairing it or shipping it out for repairs.

I'm just super cautious now after a couple of catastrophic crashes.  Parrot isn't real forthcoming about the programming details of the aircraft, and unlike an RC aircraft which has no onboard computer, the Drone is 100% dependent on the A.I. being perfect to get those 4 props synchronized.

Re: After-Crash - what I wish I had known (also tips for stable flying)

Heynewt, thanks for such a fantastic post!

When you say "Unplug. Reset." are you then referring to just unplugging the battery from the drone. Then plugging it back in, placing the drone on a flat surface, and then restarting the FreeFlight app?

I see you say to now press the reset button on the actual drone, so I'm wondering what you mean.

Thanks!

Brandon

Re: After-Crash - what I wish I had known (also tips for stable flying)

Sorry if I was unclear.  Just saying, yes, unplug the battery, plug it back in, set the Drone on a flat surface, on the iPhone reconnect the wifi, open FreeFlight, Flat Trim, then fly!

Robert

Re: After-Crash - what I wish I had known (also tips for stable flying)

Thanks for this... To bad I've read this after destorying my drone and waiting now for spare parts. But I think I found my problem with your post. This should actually have been in the manual...
Personally I also would  suggest that for your first trys you set all the settings to low, max speed for everything down not just the tilt. And buy a second akkumulator cause it takes alot longer to load then it lasts.

Re: After-Crash - what I wish I had known (also tips for stable flying)

Great work guys.  I only picked up my Drone on Friday, after having a very disappointing Christmas and not getting one! smile 

I'm very inexperienced in the world of RC flying, having only flown some smallish RC hels in the past, and all this has come in very handy.

Looking forward to posting about my experiences as I go and picking up more tips from you guys.... happy flying!

Bob.

Re: After-Crash - what I wish I had known (also tips for stable flying)

What do you mean by unplug reset?  I have had three crashes with my new ar drone and now I get a message that reads" unknown emergency"  The rest button will not clear it...any advice?  Pilot

Re: After-Crash - what I wish I had known (also tips for stable flying)

pilot wrote:

What do you mean by unplug reset?  I have had three crashes with my new ar drone and now I get a message that reads" unknown emergency"  The rest button will not clear it...any advice?  Pilot

Don't use the "reset" button on the bottom.  Instead unplug the battery and then plug it back in.  That's what I meant.

Re: After-Crash - what I wish I had known (also tips for stable flying)

Thank you so much for your post, this will help me a lot smile

Re: After-Crash - what I wish I had known (also tips for stable flying)

This is excellent - wish I'd seen it before using outside.  We had it too high and a hard landing on the lawn seems to have loosened (broken?) the landing gear.  Now, we don't have smooth vertical control (inside or outside).  The body of the drone now rests on the ground and there seems to be more "play" in the legs.  Nothing appear broken from the outside though.  Can this be repaired/fixed at home or do we need to send in for repairs.  Thanks in advance for guidance and advice.

Re: After-Crash - what I wish I had known (also tips for stable flying)

Friedman wrote:

This is excellent - wish I'd seen it before using outside.  We had it too high and a hard landing on the lawn seems to have loosened (broken?) the landing gear.  Now, we don't have smooth vertical control (inside or outside).  The body of the drone now rests on the ground and there seems to be more "play" in the legs.  Nothing appear broken from the outside though.  Can this be repaired/fixed at home or do we need to send in for repairs.  Thanks in advance for guidance and advice.

Sounds like you've cracked your cross.  Might be epoxyable, might need a new cross-frame.

Re: After-Crash - what I wish I had known (also tips for stable flying)

Heynewt!!
     You are a true God-send!  I'm sure glad I found this web-site and your article before I went any further.  I've had my Drone for a couple of weeks now, but I've only tried it out about a half dozen times.  After reading your article I can see what I've been doing wrong.  Soon as my batteries and i-Phone charge up, I think I'll have another go with it.
      Thanks again!
                                  rockrob

19 (edited by Marack 06-07-2011 04:11:10)

Re: After-Crash - what I wish I had known (also tips for stable flying)

So what your saying is, I should hold the reset button while I unplug the battery??? Just kidding smile

Re: After-Crash - what I wish I had known (also tips for stable flying)

Does it interfere if you have a hard case on your ipod does it lose a bit of control?thanks

21 (edited by stephanie60 07-11-2013 12:05:17)

Re: After-Crash - what I wish I had known (also tips for stable flying)

great post! Thank you for sharing your experience!  Texas Hold Em Tex

Re: After-Crash - what I wish I had known (also tips for stable flying)

The reason your drone goes crazy close to the ceiling....remember...sucking in-blowing out...its like a vacume cleaner and is trying to suck the ceiling. Hallways-the vortex underneath the drone is destorted due to the narrow passage end therefore causing wind in all directions...nothing to do with software or walls...or ceilings for that matter...

Re: After-Crash - what I wish I had known (also tips for stable flying)

Thank you for sharing this and some of your other posts. Very helpful for my first out of the box fight and I know it will be valueable for all future flights too!!

Re: After-Crash - what I wish I had known (also tips for stable flying)

Yo dudes, thanks for the posts. Just bought my first ever flying machine. No RC experience no nothing.
All your details will help me a lot.
I'm waiting for the first time charge to complete and the will take to the air by your description.

One thing I've read so far on a lot of posts is people saying they struggle with the drone returning back to them. I'm doing a lot of video work on the side line and what I've learned is to make the video display your primary view. So what I could suggest is to keep looking into the iPad, iPhone screen. Make the video feed yor primary view. Left will stay left and right right. Right?

Anyway, hope it works. Will post my newest experience soon!

Happy flying new pilots!

25 (edited by Seadoodude 01-18-2012 01:03:15)

Re: After-Crash - what I wish I had known (also tips for stable flying)

Great topic, but I disagree with some of the statements in the original post for new pilots. First and foremost, do not turn off the altitude limiter until you understand how the drone flies, nor do you have to set it to outdoor mode just because you are outdoors, this only makes the controls more sensitive. I almost always use the indoor settings, changing only the hull type. Flat trim is all that is necessary between landings or a crash. And do not fly in windy conditions. 5-8 mph is pretty much the limit, and be aware that winds aloft are usually quite about faster.

The below link is my experience from a lot of reading and test flights, with another link to a thread I started on another forum. It's important to realize that the sensors allowing for the autopilot to function, remarkable as it is, the drone does have limitations and only works well in the right conditions. Understanding those limitations and sensor range limits is a must.

http://forum.parrot.com/ardrone/en/view … hp?id=3771