RC India

General Topics => RC Maneuvers and Skills => Topic started by: vishalrao on June 12, 2013, 06:44:37 PM



Title: Trainer crash - What went wrong?
Post by: vishalrao on June 12, 2013, 06:44:37 PM
What could have possibly gone wrong with the crash of this trainer?

http://www.youtube.com/watch?v=QD3woSlHoJQ


Title: Re: Re: Trainer crash - What went wrong?
Post by: arun.sreelakam on June 12, 2013, 06:54:47 PM
That's sad... :(
I think a bit of more ailerons.. or the servos might have strucked and hold to a position..
What about the damages..?>:(

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Title: Re: Trainer crash - What went wrong?
Post by: vishalrao on June 12, 2013, 07:03:54 PM
Thanks Arun. The plane nose dived into water below and wing was cut. Fuse is intact..


Title: Re: Trainer crash - What went wrong?
Post by: sanjayrai55 on June 12, 2013, 07:08:26 PM
Let's see. It was flying smoothly, then a sudden nose dive  ??? ???

Probably a failure of a control surface (e.g. elevator hinge) or it's linkage.

Pilot error? Mosquito sat on his nose (been known to happen)


Title: Re: Trainer crash - What went wrong?
Post by: girishsarwal on June 12, 2013, 08:54:06 PM
I hope you did not lose range or binding mid air


Title: Re: Trainer crash - What went wrong?
Post by: K K Iyer on June 12, 2013, 10:15:31 PM
Vishal,
You won't mind a candid analysis I hope.
Before the crash
5 secs, left bank starts
4 secs, left bank is 45 degrees
3 secs, left bank is 80 degrees
2 secs, left bank is 110 degrees
1 sec, left bank REDUCED to 80 degrees.
Conclusion:
Pilot held left bank for too long (3 secs)
Tried to correct by right aileron at about -1.5 sec.
Too late. Full down elevator might have saved it.
My condolences.
Request comments of senior pilots on this analysis so that i can learn from it.
I've had 3 crashes in the last 1 year due to old age of pilot (60), old age of plane (30), fading light, fading eyesight, disorientation


Title: Re: Trainer crash - What went wrong?
Post by: vishalrao on June 13, 2013, 09:20:05 AM
Probably a failure of a control surface (e.g. elevator hinge) or it's linkage.

Thank you Sanjay. The hinges and linkages were intact. And no mosquitoes on nose :)

I hope you did not lose range or binding mid air

Thank you Girish. The plane was not more than 500 feet and the TX was Sanwa 6G. So I guess that's very remote possibility. And all the receiver wires were intact too at the time of recovery.

Vishal,
You won't mind a candid analysis I hope.

Not at all Iyer sir :) Your inputs are most welcome.

Tried to correct by right aileron at about -1.5 sec.
Too late. Full down elevator might have saved it.

I think before right aileron, elevator was given which caused a slight inside loop. I feel that giving elevator when the plane has already banked more than 60 degrees, coupled with slow speed will further aggravate the situation.

I hope you are joking when you said you were flying a 30 year old plane :)

Soliciting comments from senior pilots.



Title: Re: Trainer crash - What went wrong?
Post by: asupan on June 13, 2013, 02:44:30 PM
sorry for the loss.

I think the aileron has got stuck. Was there aileron servos or one. If two then one could have got stuck.

nitro trainers gives very time to recover. Hope you switched off power.

Regards

Asutosh
 


Title: Re: Trainer crash - What went wrong?
Post by: praveen on June 13, 2013, 03:44:56 PM
which is the Rx battery you used! voltage and mah?
Servos?


Title: Re: Trainer crash - What went wrong?
Post by: vishalrao on June 13, 2013, 03:50:44 PM
@Asutosh Just one servo for the ailerons Asutosh.

@praveen 2400 mah NiMH cells (4) for the receiver. Hitec standard servos for rudder and elevator. And Gotec standard servos for aileron and throttle.


Title: Re: Trainer crash - What went wrong?
Post by: praveen on June 13, 2013, 04:45:41 PM
well it seems you didn't had any problem with Rx battery! until n unless it was charged fully!
once i faced this problem with 50cc gasser ! it was very cold (1 to 2 degree), model started acting weird ,was locking on to one side ! like banked and no response upto 2 to 3 sec! any how landed safely ! after that i came to know battery voltage had dropped dramatically ! was using 2200mah in parallel 4400mah and 5 cell! reason :forgot to change battery after 4 flights!


Title: Re: Trainer crash - What went wrong?
Post by: vishalrao on June 13, 2013, 05:52:16 PM
No Praveen. I had charged the battery fully previous day and it was the second flight only after 15 minutes first flight.


Title: Re: Trainer crash - What went wrong?
Post by: sanjayrai55 on June 13, 2013, 07:20:35 PM
Did you check the voltage of the Rx pack post-crash?


Title: Re: Trainer crash - What went wrong?
Post by: vishalrao on June 14, 2013, 08:41:04 AM
I didn't check the voltage but I did charge it and the units that went through was not more than 1000.


Title: Re: Trainer crash - What went wrong?
Post by: rcpilotacro on June 14, 2013, 11:03:48 AM
Vishal

where did you secure the bat, behind the fuel tank in the empty space ?. did you secure it wrapped in a foam, and batt and extension secured properly, could it have been that that the rx lost batt power fully,in the left turn due vibration/ dislodging and falling off


Title: Re: Trainer crash - What went wrong?
Post by: vishalrao on June 14, 2013, 11:22:53 AM
Augustine sir, the receiver battery was held in place with velcro (below wing, not in fuel compartment) and it was in place (with wires intact) after recovery.


Title: Re: Trainer crash - What went wrong?
Post by: rajaram on June 14, 2013, 05:08:49 PM
http://www.youtube.com/watch?v=EjvJAPwLQ9c

Recovery  ;D ;D ;D


Title: Re: Trainer crash - What went wrong?
Post by: vishalrao on June 14, 2013, 07:09:11 PM
Ha Ha  ;D Was waiting for that!


Title: Re: Trainer crash - What went wrong?
Post by: sanjayrai55 on June 14, 2013, 09:21:21 PM
Loved the water coming out of the holes as it was drained  ;D {:)}

I think you should make an RC boat  :giggle: :giggle:


Title: Re: Trainer crash - What went wrong?
Post by: K K Iyer on June 14, 2013, 10:01:10 PM
Twin exhausts!
Awesome rescue from shark bite on right wing tip.
Pl add details of location and circumstances.


Title: Re: Trainer crash - What went wrong?
Post by: VC on June 14, 2013, 10:36:50 PM
All is well, all is well  {:)}


Title: Re: Re: Trainer crash - What went wrong?
Post by: arun.sreelakam on June 14, 2013, 10:59:02 PM
Vc sir its all iz well... all iz well...
:p


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Title: Re: Trainer crash - What went wrong?
Post by: Nithinraj Kotian on June 15, 2013, 11:05:00 AM
@ sanjay sir : when crash took place, we started running towards the river and started asking help from the local people who were having the boats but no one was ready to rescue our plane  :banghead: :banghead: later some workers came near us and that time vishal sir requested them. :salute:


Title: Re: Trainer crash - What went wrong?
Post by: shobhit17 on March 09, 2014, 04:15:32 PM
http://krepelka.com/fsweb/lessons/private/privatelessons02.htm (http://krepelka.com/fsweb/lessons/private/privatelessons02.htm)
Mind if you guys read this article.... To me it appears that nothing went wrong... Its just that the pilot was not aware of what to do when in a steep turn.  When we do a LEVEL steep turn the lift of the wing reduces due to a reduced plan form projected to the lifting force and the aircraft enters a descent.  Hence to maintain the lifting force required some amount of UP elevator is required.... when this is done the strn becomes tighter and the "G" forces increases.... Mind you I am talking of a level steep turn.... or else you will be in a descent and this descent may turn into a spiral which keeps getting tightened and ends up in a crash.  Any pilot when doing a steep turn needs to pull the elevators up... therefore in a level steep turn the up elevator is necessary and because of this the "WING LOADING" increases resulting into increased "G" forces.  As a thumb rule in a 60 deg turn the "G" required is 2"G" i.e. two times the gravitional force as felt by the pilot.... if the wing is not strong enough it will show a bend i.e the tips will flex up and in an extreme case they will fold up and break. To fly safe.... avoid turns with more bank than 30 dec... in case doing a steep turn be ready to apply UP elevator...

Happy and safe flying