Mast bumping and other helo terror

[mmx1]

MB Isn't talking about using bank angle to increase descent rate (although it probably would to a degree). He is saying that using angle of bank to positively g-load the rotor-head while descending keeps you from the zero-g regime while still descending.

Lift vector goes sideways, smaller vertical component -> greater acceleration downward for the same (positive) g-loading. So, I shouldn't have said descent rate, downward acceleration is more accurate.

At least that's how I understand it. Semantics, of course. :icon_wink

 

[Godspeed]

Anyone have any videos of mast separation in flight? I searched Youtube and Google but couldn't find any.... Sounds ridiculously catastrophic.

 

[BACONATOR]

Lift vector goes sideways, smaller vertical component -> greater acceleration downward for the same (positive) g-loading. So, descent rate is the wrong verbiage, downward acceleration is more accurate.

At least that's how I understand it. Semantics, of course. :icon_wink

I understand what you're saying and it's correct, but what I'm getting at is that your point is NOT the reason for rolling into a bank angle.

If you want to drop down after a cliff drop off, you can roll into an angle of bank, dump collective (which is REALLY what is creating most of your descent) and pull positive g's while descending (due to your collective reduction) which prevents the 0 g which would occur while dumping collective straight and level, and stay in a safe flight envelope.

The increased descent rate due to bank angle is not being discussed. It's the g pull during the roll which keeps the rotor-head loaded which allows for a safe descent. At least that's my noob take on this aerodynamic situation.

 

[BACONATOR]

Anyone have any videos of mast separation in flight? I searched Youtube and Google but couldn't find any.... Sounds ridiculously catastrophic.

Just picture a helicopter at altitude without the big spinny things on top. You do the math.

 

[phrogdriver]

I've sort of lost my taste for aviation "Faces of Death" videos. After a close call or two, you start to think that maybe you don't want your last moments on earth to earn 100,000 hits on YouTube from drunk college kids shouting "Holy shit! That HAD to hurt!"

 

[Lawman]

I've sort of lost my taste for aviation "Faces of Death" videos. After a close call or two, you start to think that maybe you don't want your last moments on earth to earn 100,000 hits on YouTube from drunk college kids shouting "Holy shit! That HAD to hurt!"

My career goals as an Army Aviator have gone from hero bad ass Chuck Norris Fantasies to not doing something they later show the video of at flight school.

 

[2Blades]

I understand what you're saying and it's correct, but what I'm getting at is that your point is NOT the reason for rolling into a bank angle.

If you want to drop down after a cliff drop off, you can roll into an angle of bank, dump collective (which is REALLY what is creating most of your descent) and pull positive g's while descending (due to your collective reduction) which prevents the 0 g which would occur while dumping collective straight and level, and stay in a safe flight envelope.

The increased descent rate due to bank angle is not being discussed. It's the g pull during the roll which keeps the rotor-head loaded which allows for a safe descent. At least that's my noob take on this aerodynamic situation.

I think you are explaining the technique that I sometimes use when TERFing. Following a bunt or roll over a ridge/finger, kick the tail out so you are perpendicular to the piece of terrain as you descend on the oppsite side of the ridge/finger. Sometimes that helps with large ridges/fingers so that you are not pushing the nose far foward (low g) to make the bunt/roll then have to make a lot of aft cyclic to reduce your airspeed and then putting your tail close to the terrain.

Mitigate flight in low g by the rate at which you push foward cyclic. Use slow smooth foward cyclic.

 

[Flying Low]

Bunting is what you use to advance a runner usually at the cost of getting yourself thrown out.

 

[S.O.B.]

Bunting is what you use to advance a runner usually at the cost of getting yourself thrown out.

You can also bunt for a base hit.

 

[FlyinRock]

My career goals as an Army Aviator have gone from hero bad ass Chuck Norris Fantasies to not doing something they later show the video of at flight school.

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OooRahhh! You must have developed a few gray hairs! Mine is damned near snow white now! I love that saying.
I had mast bumping in a Hiller 13ET while spraying timber in Oregon years back. Landing in a confined slope area when I shed a collective weight - one of those square rabbit ear looking thingies. What a ride that was. I thought sure I'd either hit the tail rotor on a big damned snag behind me, ot I'd cut off the tail boom. When everything settled down and the blades stopped turning, I found a bright metal ring around the mast where the head had been rubbing. Made a believer of me. The weight had sheared off the control rod where the bolt went thru. You could not have found it unless you disassembled the unit. Not sure if there is an AD on that now or not.
Semper Fi
Rocky

 

[MH-Z]

Roll..

You can maintain 1g and still come down.

In the 60, we demo flight in low G conditions to FRP's to show them why they shouldn't put the helo in those situations. Push the nose over and gain some speed, pull up ~3 degrees nose up for a second then abruptly push forward to unload the head. Then roll to one side and see how long it takes for the head to start having an effect and pull through the turn.

We also show them what 30 deg nose up looks like... but when we recover, we roll right to keep the head loaded.

 

[MasterBates]

Oh I remember most of that crap from 60Bs. Mostly with breaklock and LSF Intercept is when it came into play. I also remember some "fun" ridge crossing techniques from when I was flying teeter-totters.