Strange thing happen and causes my TRex to crash

[Super-Hornet]

This morning, I was flying my flybarless + elevated tail trex on the left side while one of my flying buddy (Adrainli) was flying on the right side. As I was doing a figure 8 and turning from left to right, by flying buddy trex was going from right to left.

Suddenly we realise we are in the collison course and it was like mm to each other appart. We both do a evasive maneuver. He bank and turn right while I band and turn left. Suddenly my TRex go piro spinning out of control. Both of us was like flying in eye level height so I have no choice but to cut power and prepare for crash.

My TRex hit the ground with 45 degree angle downward. Damage one piece of blades, bend spindle and and main shaft, broke the battery compartment (which can epoxy back) and broke one of the flybarless mixer (Servo horn actually) and also lost one linkage (From the broken mixer)

The question is, how the heck it goes piro out of control? Both of us sworn we did not hear any helicopter "kissing sound". His TRex do not suffer any damage and was able to fly till battery flat.

Initially I was thinking of belt loose and when I do intensive maneuver, it gave way but I check and recheck it is ok.

I finally came out an theory that maybe due to my TRex was in elevated tail, when my TRex tail was too close to my buddy TRex main rotor wash, it suffers from air turbulance and finally lose its aerofoil/airfoil ability (in this case, hold the tail).

So how do you all think?

SH

[AceViperX]

I say you're thinking too deep. Sounds to me like a mechanical failure.

[Brandon Chng]

I say you're thinking too deep. Sounds to me like a mechanical failure.

Second That

[fuse]

third that

[Syphonics]

I say you're thinking too deep. Sounds to me like a mechanical failure.

maybe belt loose

[rkte]

I had encountered the tail spinning after did evasive manuver.
Predicted that the 3 pins connector from receiver to gyro a bit loose, so when the evasive manuver happened, there was disconnection between receiver and gyro that made the tail blade stop spinning then the heli spin like crazy

[koon]

It happened to my elevated tail Trex before,quite difficult to explain without showing you the eletail.. explain to you next time we meet (in hokkien I can elaborate better )

[Adrianli]

[genexis]

so adrainli, any casualty on your side?

[Adrianli]

so adrainli, any casualty on your side?

Nothing happen to my Trex. Avoided collision, continue to fly till batts flat n landed nicely near my feet.

When I realised I was on collision coz wif SH, I punch the Trex up and away. The next thing I heard n saw was SH Trex loose tail authority n piro to the ground. When I punch up my Trex, it was above SH Trex. I also got no idea how come SH Trex will piro to its death.

After I landed, I went to check on his heli n saw that his belt n tail case r all in tact, no belt slip or linkage failure leh.


This is really weird. Would really like to hear from Koon his experience.

[Brandon Chng]

remotest thing i can think about, although i've never seen this happen to r/c helis. not to mention changing of effective angle of attack due to adrainli's downwash.

Conditions Under Which LTE May Occur
Any maneuver which requires the pilot to operate in a high-power, low-airspeed environment with a left crosswind or tailwind creates an environment where unanticipated right yaw may occur.

There is greater susceptibility for LTE in Right Turns. This is especially true during flight at low airspeed, since the pilot may not be able to stop rotation. The helicopter will attempt to yaw to the right. Correct and timely pilot response to an uncommanded right yaw is critical. The yaw is usually correctable if additional left pedal is applied immediately. If the response is incorrect or slow, the yaw rate may rapidly increase to a point where recovery is not possible.

Computer simulation has shown that if the pilot delays in reversing the pedal control position when proceeding from a left crosswind situation (where a lot of right pedal is required due to the sideslip) to downwind, control would be lost, and the aircraft would rotate more than 360° before stopping.

The pilot must anticipate these variations, concentrate on flying the aircraft, and not allow a yaw rate to build. Caution should be exercised when executing right turns under conditions conducive to LTE.

[rifqi]

post from brandon reminds me of a scene from topgun, whereby the jet was hit by jet wash and the jet was piro-ing down and crashed..

maybe same concept?

[Art]

Pilot Error?

Or Maybe it's the mod on the tail?

I have no knowledge of elevated tail's holding power versus the conventional setups....maybe some other experts in this field can fill us in on the above?

[Super-Hornet]

Hi all

Today I manage to do some testing on phenomena... (Don't ask me how exactly I test it )

While testing my Four Blades main Rotor TRex in confine hover, I do notice that everytime when the tail are close to some object, a turbulance kind of sound or rotor to close to object sound would heard. When that happen, the tail seem like loosing its power a bit.

Maybe that is why I crashed my heli on that time (long time ago). This is maybe a "Myth" that need to be prooven to be "Confirmed", "Plausible" or "Busted"

EDIT: Oh.. just in case u might thought of the tail blades actually creating a suction that suck the tail towards the object... but it is not because the object is on the "top view of the tail rotor" and the effect is that the tail move away from it as if the tail is loosing power.

SH

[AceViperX]

Yeah but after your heli went all whirlybird and got out of the so-called downwash of the other heli, the yaw should have stopped. What was yours doing?