Chopping my rotor without warning

[LupinYonder]

Hi there, having a frustrating problem while trying to turn at arround 150-200kph. Trying to change my direction of flight i think im using too much rudder and not banking the aircraft enough, anyway without warning the rotors collide :-(

 

Should i be banking more while turning at these speeds?

 

Whats the correct sequence when changing direction at these sort of speeds i.e. from one WP to next. :huh:

[Frederf]

Hmm, it should be pitch up G loading that would cause rotor collision, yes? Hard rotor disk loadings at high speeds? Getting a rotor collision from mostly yaw in put doesn't sound right to me.

 

I would think that a coordinated turn at 2.5 G or so would be alright. I guess one accepts that there's a maximum deg/sec one can achieve in a level turn.

[fox_111]

At highspeed, I pitch up a little, bank the chopper and simultaniously give a little rudder to iniciate the turn. Pulling the stick enought to turn but not climbing to much (ajusting collective).

 

After the turn, the rudder pressure must be maintained to keep the nose pointed in the right direction. The aircraft usually aling itself on it's own and rudder pressure can be slowly relased.

 

That's the best way I found for turning at most speeds without ending out of control or ripping those propellers appart.

 

Fluid movements is the key I think.

[LupinYonder]

Thanx for your input Fox and Fred, i think its prob my lack of banking thats the problem, sometimes during the turn with mostly rudder i find the chopper rears up like a startled horse :-) i like the idea of pitching up b4 a turn to keep alt level while banking and will try that in future.

 

Cheers and merry christmass

[GGTharos]

Don't try to throw it around like a fighter and you'll be fine. :)

[bradmick]

If you haul it over to the left or right and then pull a lot of aft cyclic (more a result of the aft cyclic though) you're going to induce a lot of rotor coning. It seems that the lower rotor disc cones far more than the upper, and as a result leads to this condition. I was trying to do a pitch back turn/return to target and all was going well until I was pulling a lot of aft cyclic and got a little to aggressive on the roll...needless to say I chopped my own blades off and buried the nose in the dirt. Was impressive to say the least :)

 

Brad

Edited December 22, 2008 by bradmick

[Yo-Yo]

How to avoid blades collision.

Thre are several simple rules of thumb:

 

1. Perform gentle control input when your helicopter has angular velocities around any axis. Inertial forces coupling with your inputs can do a great job... This rule is for the whole IAS range.

2. Do not underspeed the rotor. Yellow warning lamp helps you to maintain necessary rotor rpm.

3. Watch the turbulence. If you see signs of it be very careful. No abrupt maneuvers at all. No significant right pedal input. Turbulence and overspeed conditions are deadly dangerous.

By the way, if you are in hard situation and are waiting for blades collision - use left rudder... and you will have more chances to survive.

[BattleMetalChris]

As far as I'm aware it's the fact that you're going very fast, combined with very high loads on the rotors, which causes them to collide.

At low speeds, both cone by similar amounts, but at high speed, the retreating blade 'bites' the air less (because its speed through the air is less - the blade's speed minus your forward speed) meaning the rotor cones more on one side. Because the two rotors spin in opposite directions, you get the high cone on opposite sides for each rotor, so eventually they touch, with appropriately disatrous consequences.

 

Knowing that - slow down or don't turn so hard and you should stop it happening.

[LupinYonder]

would anyone recommend a safe turning speed for say a 45deg turn? is 200kph to much or is it ok if i do it gently with enough bank and less rudder, btw i was turning right at the time i lost my rotor and i think some one mention right rudder was more of a factor.

[GGTharos]

It's alright if you do it gently. Just don't throw the chopper around - it's not meant for the sort of violent maneuvers you fly in LOMAC. You'll probably find 150kph a comfortable speed, and 250 a good cruise speed when the turning is easy and gentle - unless there's turbulence, then take care to slow down.

 

Your rotors are closer together on the right side. If you put in right pedal, they get closer ...

[haigotron]

 

Your rotors are closer together on the right side. If you put in right pedal, they get closer ...

 

are they close at all times? if so why? or is it during a turn?

[GGTharos]

At all times ... because the upper rotor has less lift on that side - the bottom one is rotating in the opposite direction, so it has more lift on the same side.

[LupinYonder]

I have just been trying out a few things and have found a system thats working for me. I'm Pulling back a little then banking and applying gentle rudder and then pushing forward, kinda like lifting the nose up and over a rock :-) works fine at speed, kinda like what bradmick said.

[Jeevz]

I managed to smack the tail with the rotors yesterday. I'd gotten myself into a vortex ring, so I nosed down to fly out of it but in doing that I was too close to the ground so I hauled back on the cyclic and collective trying to climb out of it and heard a BANG!

 

I was thinking, "there go my rotors" and I was reaching for ctrl+eee when I realized I was still flying. I flipped to F2 view and there was a big chunk missing from the front of the tail but the rotors were fine. Even finished the mission, Russians build those birds tough.