Aero-M Test Flights - SCARY!

Hello Everyone!

I feel compelled to share my less than impressive experience with this product after my first three test fights with the Aero-M mapping UAV.  This is actually my second unit, sent to me as a replacement to my original Aero-M which I crashed on three of my four take-off attempts several months ago.  The damage to the nose section was so severe on the last crash that it was irreparable and I ended up sending it back.  Low and behold, however, this new replacement Aero-M has EXACTLY the same flight performance issues as my first one!  It's all indicative of an inherent issue with this airframe's design...

Here is what's been happening:  The Aero-M has a nasty tendency to nose-dive on takeoffs (the most critical part of any flight).  And it doesn't matter if you apply a LOT of up elevator trim, or use different flight modes.  It doesn't seem to make a heck of a lot difference.  I tried taking off in Manual, Stabilize and FBWA modes with the same results.  The only two reasons why I managed not to crash my new replacement Aero-M today were a) my 27 years of RC flying experience and b) my still quick reflexes to move my launching hand down to the elevator stick on the RC transmitter within a split second of letting go of the plane on launch to quickly apply up elevator to save it from hitting the ground.  But the issues don't stop here, unfortunately.

I expected this unit to be well trimmed "out of the box" because, after all, it's marketing as a RTF (Ready To Fly) UAV.  This is not the case.  Despite being balanced, as per the manual's diagram of the CG location, the Aero-M continued to want to fly downwards at various throttle settings.  I had to trim the elevator to maximum up trim to get it to improve.  But then it began behaving as if it were tail heavy, flying this roller coaster pattern throughout the sky.  When I saw this, I didn't know what to think (too nose heavy?  too tail heavy?).  It also had a tendency to keep veering to the right, requiring quite a bit of left aileron trim to straighten out.  I will have to do more flight tests now to figure out where the CG actually needs to be.  Not something I was planning on when I purchased it...

I also tried my first mapping mission, which was also a bit of a disaster.  I set up a small polygon with just four passes to check the camera.  I don't know if I set the polygon too small in size (it was roughly 200m x 200m in size), but the Aero-M had a ton of trouble properly lining up for the waypoints, and tracking them in a straight line.  The about-turns at the ends of the passes were also way too wide, putting the plane out of position of the next waypoint.  I had a 70m length set up for the turns at the ends of each pass.  

Finally, the UV filter that is supposed to be protecting the camera's lens during mapping causes the images to be unusable for real mapping work because it causes a reflection in the imagery.  It's a lot like when you try to take a picture of something through a glass.  It doesn't work.  For mapping, the UV filter must be removed so that there is nothing in the way of the camera's lens and the objects on the ground.  Yes, the camera lens can potentially get scratched or dusty, but I can tell you from my professional experience mapping tens of thousands of acres of fields every season that it's not that serious a problem.  We have used the same Canon SX260 cameras for our work for two seasons now, and they still produces excellent quality imagery.

I wish I had something more positive to say about the Aero-M, but unfortunately we cannot use it, as is, for the very purpose for which we had purchased it - aerial mapping.  

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Replies

  • Developer

    Hi Jan,

    I have a prototype of the Aero and have flown it a lot. Like many electric gliders there are two things apart from the CoG that affect takeoff:

      1) don't throw it too hard. A lot of people think you need to give it a really big push on takeoff. Given you are an experienced pilot you probably aren't doing this, but I have seen people experienced with other types of models make this mistake. I tend to do a gentle run then a quite small level push for launch

      2) don't takeoff at full throttle. With 4S and a fully charged battery the skywalker can be overpowered at launch. I takeoff at about 2/3 throttle then raise it for climb out. For auto-takeoff I use these settings:

    TKOFF_THR_SLEW=75

    TKOFF_THR_MINACC=7

    TKOFF_THR_DELAY=2

    TKOFF_THR_MINSPD=4

    TKOFF_THR_MAX=80

    so the engine doesn't start immediately, but waits for the launch, and then advances the throttle over nearly 2 seconds to 80%.

    The other obvious one is CoG. As long as the CoG is close to the wing spar channel in the wing it should be fine.

    I've found auto-takeoff to be very reliable with the above settings.

    Cheers, Tridge

    • Hi Andrew,

      Thanks for all your suggestions.  I must admit, now that you mention it, that I might in fact be launching it a bit too hard.  Flying UAVs for a living, I am used to our platforms being much heavier than conventional RC planes with the extra batteries, cameras, autopilot, etc.  

      I like your slow advance of the throttle setting.  I've been trying to tweak that as well during cruising speeds because the default setting was causing the throttle to constantly throttle up and down in rapid successions which obviously kills the battery much faster.  I actually reduced the throttle slew rate to about 30 which seems to have helped.  But looking at your settings for Auto takeoff I wonder if I should also look at the other throttle settings to further smooth the increases/decreases of throttle during cruise speeds.  

      • Developer

        Hi Jan,

        Throwing too hard is a common issue. I recently lost a foam model I was testing when I gave it to a friend at the field to launch for me, instead of launching it myself. He was experienced with RC, but not with small foam models. He threw it much too hard and it flipped over on launch. There is nothing the flight controller can do about this - there isn't enough control in the surfaces at low speed to correct for a really hard throw.

        I fly everything from 1kg foamies up to 20kg 50cc petrol planes, so I am used to making the launch match the airframe. If you aren't, then it's easy to go wrong :-)

        The Aero (a skywalker) is actually a great plane when you are used to it. I find it quite a bit easier to launch than the X8, especially for hand launch, and it is much safer as the prop can't hit your hand, even if the wind catches during launch.

        Another plane I really like is the RangerEx. Definately worth a look, and it can carry a lot more battery than the Skywalker.

        Cheers, Tridge

  • jaideep gour

    my advice (which I have taken myself and heard many times on these forums) is due to your inexperience would be to start with something small and cheap and work up to the big project. I was in the same boat with no RC flying experience.  Buy something small and cheap and practice flying, it doesn't take long to get some idea and will reduce expensive failures/crashes on the main project. 

    Learning mission planner and ardupilot took some practice/learning too so best to learn on something cheap and build your confidence to then apply to the main project.

    • Jon,

      Thanks for the valuable advice. So, could you suggest something which is small and cheap. What setup did you use when you started flying ?

      Jaideep

      • Well, I like flying wings so I bought a Wing Wing Z-84 (~$50-$80) and used this to learn how to fly/set up a flying wing. Only 80cm wing span and very light and hard to break. Crashed it may times, nothing glue or tape could not fix. I added apm to it and learnt a lot and progressed through each flight mode and the parameters.

        Once that set up was working well I bought the FX61 (155cm wing span) which is basically same plane but bigger and just transferred all the electronics over and set it up much quicker with more confidence and had a smooth process to getting that set up flying well.

        Just have a look on hobbyking for something small that looks similar to the type of plane you will get for the main project. Practice and play around with it and learn about flying before getting something expensive. 

        • Thanks Jon,That's a very good idea. I would like to go with this approach. Let me discuss this with my adviser.

          Jaideep

          • Hi Jaideep,

            I totally agree with Jon.  Practice makes perfect. :)  Another airframe suggestion I would have is to look at the X5 on HobbyKing.  A much smaller wing and very robust.  I am actually new to wings myself, with the X8 being my very first one to fly.  As long as you have your CG perfect (wings are very sensitive to that) they are amazingly easy to fly, and very stable which is what you want.  

  • Could have bought an RF-70.

    • Love the promo video!!  Don't remind me what I could have bought... It's so easy to get sucked into all the convincing marketing out there from the various UAV suppliers.  In most cases, however, their claims and reality are miles apart and by the time you realize it it's too late.  Really hard to know whom to trust.

      I actually also fly the Skywalker X8 wing.  It's super stable as well and a great platform for aerial surveys.  I am currently pushing it to cover half a section (320ac) per flight.  Almost there, just need another 50 acres to hit that.  I bought it specifically for the purpose of large area mappings, as we do a lot of crop monitoring during the growing season.  We are already past 25,000 acres flown since June.  

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