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VNE What a Gotcha, but?


FragBum

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Hi All I've been doing some more practice in the Gazelle (minigun ver) and I find I'm getting into, well, a tad above VNE in some maneuvers.

 

The situation feels good as far as the Gazelle feels and the urge to roll right gets stronger until you either bleed off speed, yes you've got to catch it early or I make an unscheduled and somewhat impromptu landing, well you know what I mean.

 

So my question is although it "feels" right, can anybody confirm the behavior?

Control is an illusion which usually shatters at the least expected moment.

Gazelle Mini-gun version is endorphins with rotors. See above.

 

Currently rolling with a Asus Z390 Prime, 9600K, 32GB RAM, SSD, 2080Ti and Windows 10Pro, Rift CV1. bu0836x and Scratch Built Pedals, Collective and Cyclic.

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It's called retreating blade stall. The difference in lift between the sides of the rotor disk caused by the different relative airspeed of the retreating and advancing blade exceeds what blade flapping can compensate for and causes a nose up pitch and right roll. Nose up and left roll for American helicopters.

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Yes I know what it is thank you I have read Wagtendonk 's text. :)

 

My question is, and yes it gives the impression of exceeding VNE for me as far as the sim goes, but is that what it is like approximately? I guess more to the point is it say as realistic to evade it much like VRS if you get it early enough?

Control is an illusion which usually shatters at the least expected moment.

Gazelle Mini-gun version is endorphins with rotors. See above.

 

Currently rolling with a Asus Z390 Prime, 9600K, 32GB RAM, SSD, 2080Ti and Windows 10Pro, Rift CV1. bu0836x and Scratch Built Pedals, Collective and Cyclic.

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To be fair, I only talked to 1 Royal Air Force Gazelle instructor who told me the scariest situation in his 4000 hours Gazelle time, next to Lynx and other. They entered a very early stage of retreadingblade stall and the student recoverred. despite the fact that they enterred level flight 3 feet of the deck at a speed exceeding from normal, the IP told me that he thought that is was the end of all for him in that minute and nearly did shit his pants. His conclusion about retreading blade stall. If you enter it that bad as people like to do it in sims, you areto 100% dead in RL. So nobody of the RL pilots will be able to give you a real answer. The once that maybe could are dead. The once that can give an approximate answer might be a few to none cause I figurred, since working a lot closer with some US Army pilots and knowing some frech army pilots, that the pilots that fly combat style know exactly the limits of thier aircraft and never exceed it.

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My apologies Frag I miss understood the question. It's unlikely anyone could tell you what fully developed RBS is like. Its made worse by high altitude, temperature, gross weight, and bank angle. I have up in the mountains felt a vibration similar to VRS that is indicative of its onset but I quickly slowed down. I know someone who claims to have experienced it while flying an R-22 at an irresponsibly high altitude. He claims the aircraft just flipped inverted on him faster than he could think but I doubt his credibility given the 22's tendency towards mast bumping.

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Good to know Borchi and Jester986, yes I understand the severity and figure the modeling is very good then.

 

I do appreciate what one can do in a sim vs real life, no matter how many times we push the boundaries we get to walk away.

 

I've not noticed shaking (busy sh#tting my virtual pants at the time :D) but the sudden roll and nose up which becomes a full roll in nought seconds flat. Left cyclic and nose up to bleed speed.

 

Appreciate the answers thanks. :thumbup:

Control is an illusion which usually shatters at the least expected moment.

Gazelle Mini-gun version is endorphins with rotors. See above.

 

Currently rolling with a Asus Z390 Prime, 9600K, 32GB RAM, SSD, 2080Ti and Windows 10Pro, Rift CV1. bu0836x and Scratch Built Pedals, Collective and Cyclic.

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  • 2 months later...

Control is an illusion which usually shatters at the least expected moment.

Gazelle Mini-gun version is endorphins with rotors. See above.

 

Currently rolling with a Asus Z390 Prime, 9600K, 32GB RAM, SSD, 2080Ti and Windows 10Pro, Rift CV1. bu0836x and Scratch Built Pedals, Collective and Cyclic.

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  • 2 weeks later...

 

My question is, and yes it gives the impression of exceeding VNE for me as far as the sim goes, but is that what it is like approximately? I guess more to the point is it say as realistic to evade it much like VRS if you get it early enough?

 

Certification of helicopters call that VNE is marked not higher than 0.9 x the safe demonstrated indicated airspeed. IRL you won’t get into problems until at least a higher speed than 1.11xVNE.

I didnt read the module manual but due to the gyroscopic precession the retreating blade stall should mainly make the nose go up. Theres a lot of argument in other places about right roll or nose up, so we might not go there.

Also, not all helos VNE is due to retreating blade stall. Some have other issues like bending forces on the rotor mast and so on.

 

There is also the possybillity to stall the main rotor ( or part of) by G forces. This behaviour is closely related to retreating blade stall ( easiest to enconter in higher speeds) and at least in the Bo105 it gives a clean nose up( actually not really nose up but tail down due to lost lift).

[T.M HOTAS Warthog Stick & Throttle + T.Flight pedals, Varjo Aero, HP Reverb pro, Pimax 8KX] 🙂

[DCS Mirage 2K; Huey; Spitfire Mk IX, AJS 37, F-14, F-18, FC3, A-10 Warthog II and a few more ]

i9 13900KF@5.8/32Gb DDR5@6400/ Gigabyte Gaming OC RTX4090, ASUS STRIX Z790-F , 2Tb m2 NVMe

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Umm interesting RBS in Gazelle does, well as far as the sim flies it feels like the the helo just dropped right side down rather then a lift to the left. :D

Control is an illusion which usually shatters at the least expected moment.

Gazelle Mini-gun version is endorphins with rotors. See above.

 

Currently rolling with a Asus Z390 Prime, 9600K, 32GB RAM, SSD, 2080Ti and Windows 10Pro, Rift CV1. bu0836x and Scratch Built Pedals, Collective and Cyclic.

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Umm interesting RBS in Gazelle does, well as far as the sim flies it feels like the the helo just dropped right side down rather then a lift to the left. :D

 

 

You might wanna google [gyroscopic precession]. If you loss lift on retreating blade perpendicular to the helo nose direction, the resulting lost lift comes in action 90 degree later in the rotor rotation.

 

 

Steering input is faced 90 degree before the desired action to counter the gyroscopic precession. If you like to roll right with the Gazelle, and move the cyclic to the right the blades will increase the blade angle straight back/over the tail boom, and decrease the blade angle straight forward.

[T.M HOTAS Warthog Stick & Throttle + T.Flight pedals, Varjo Aero, HP Reverb pro, Pimax 8KX] 🙂

[DCS Mirage 2K; Huey; Spitfire Mk IX, AJS 37, F-14, F-18, FC3, A-10 Warthog II and a few more ]

i9 13900KF@5.8/32Gb DDR5@6400/ Gigabyte Gaming OC RTX4090, ASUS STRIX Z790-F , 2Tb m2 NVMe

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