Return to home went a little nuts...

Discussion in 'ALTA' started by Rick Gerard, Mar 5, 2018.

  1. Rick Gerard

    Rick Gerard Active Member

    Apr 22, 2017
    Likes Received:
    I'm not sure I did this right but here is what happened. This was my second flight. The first flight was fairly short and all manual.

    Booted up as normal, checked the Alta App, everything normal, preflight check normal, Armed and started motors, turned on the safety, checked controls correct, set home position and returned the switch to the center position, spooled up and took off and climbed to about 30 feet. So far a normal checklist.

    So far so good. Switched to position mode and the aircraft started to climb slowly so I fine-tuned the throttle by adjusting the position slightly. Hover ok but the aircraft was drifting slowly east then it started to slowly climb again. Kept fiddling with the throttle to try and stop the climb. It is now at about 100' and about 500' away from me. I made a few turns and brought it back closer to me. I was still not very happy with the position mode because it would not stay put. It kept slowly drifting to the east.

    After about 3 or 4 minutes the Alta was about 300' away and at about 50' and drifting again. I tried the return to home switch and it took off to the east. It was moving fairly quickly so returned the switch to the center position, went back to manual control and brought it back home. It was kind of scary because for a few minutes I had no control of my aircraft. With just a little more flight time remaining I put it back in position mode, still drifting, then moved into position for landing.

    Everything went just fine until I got down close to the ground. I switched to Manual to land and got it down but it was drifting slowly toward me. One of the gear legs sunk into a soft spot just before I got it stopped and the Alta immediately flipped upside down damaging all 6 propellers before I could get the motors shut down. I should have set had the safety switch off before landing before landing. If I had been able to shut down quicker it may have only ruined 2 or 3 instead of all 6.

    So there were two problems with the flight. The expensive one was due to my inexperience and no pre-landing checklist. I have one printed up now and stuck to the transmitter. The other is probably a two-part problem but I think they are related. Has anyone else had the Alta just take off and fly away when the return to home switch is thrown? Is it normal to set the home point before takeoff or do you just let the GPS find the current position? I did not expect to have constant height control issues in the Position mode. I thought that altitude should be pretty stable. I never did try the Height mode only. Maybe that would have stopped my constant fiddling with the throttle to maintain altitude at 50% throttle.

    Any feedback would be appreciated. I would really like to find another Alta pilot in the area to spend an hour with going over procedures and expectations. My preflight training has been flying my Phantom 4 pro in the A mode - no GPS and I feel pretty confident flying the Alta in manual mode even though my second landing was a disaster. If the landing area was not so soft I probably would not have had any problems. I should have used a landing matte. I have one but forgot it. https://www.harborfreight.com/4-piece-anti-fatigue-foam-mat-set-94635.html

    Thanks for your feedback.
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Jul 31, 2012
    Likes Received:
    Hi Rick:
    Sorry to hear about the incident. I infer that this mishap happened yesterday (March 5), correct? I need to be able to check the KpIndex.
    Can you also tell me the approximate location where you were flying so I can see the weather conditions?

    Also, could you upload the flight log to the forum, please? There is a flight Data Viewer available from Freefly that you (or anybody else) can use to review the flight data and see what happened.

    The thread is here, but be sure to go to the end of the thread to find the latest version of the Data Viewer (it requires Windows).

    Question 1: When you engaged RTH on the transmitter, do you recall what the Status Light was doing? What color was it and was it flashing or not?

    Based on what you wrote it's a bit hard to understand why Return to Home would have done what you said.
    Question 2: Have you used RTH successfully before, please?

    If not, the first thing I would check is to make sure that the mapping of the Return to Home switch is correct. On the Futaba 14SG, with the Switch C (SC) in the middle (off) position, Channel 6 should be in the 0 (central) position (on the Servo Monitor screen), with the Switch in the Return to Home position it should be showing the lower part dark on the screen and +100 beneath that.

    Channel mapping is covered on page 38 of the ALTA Flight Manual (Revision D).

    Question 3: Please confirm that this is the case. If it's not, the RTH switch will not have triggered the Return to Home in the ALTA.

    Question 4: Is there any chance that you might have inadvertently operated the Set Home feature (it's on the same switch as the RTH) and set a new home point? It would have the effect of causing the RTH switch to go to a new "home in the sky" so to speak? The Flight Log will answer this question.

    As to the flip-over -- the ALTA's rotor downwash is significant -- much more so than the Phantom's -- and so when you land, the full weight of the ALTA does not transfer to the landing legs as quickly as it does on the Phantom. That will have the effect of making the ALTA more buoyant than the Phantom and it sound like that might have caught you by surprise if you did not have the disarm switch set ready to kill the power to the motors. Also any horizontal drift when the aircraft's weight is not fully on the landing gear will cause it to "trip over" it's own landing gear, I'm afraid. That's just the physics of the ALTA and landing gear. (Sorry--I realize this is probably not want you wanted to hear).

    I'll have a look at the flight log when you post it.


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