Agusta 109 Grand vs Wessex

[Floppy Link]

Pilot Magazine, November 2006, Pat Malone's flight test of the Agusta 109 Grand

According to Agusta, it's impossible to get ground resonance with three wheels and a four bladed rotor, but as with anything in the helicopter world, it's only impossible until somebody does it.

...which reminded me of the song:

"There's a Wessex on the ground
With the rotors turning round
and it jumps up and down and shakes itself to bits
and gives the passengers the sh1ts sh1ts sh1ts"




So who was right? All of us drunkenly singing in happy hour, or Agusta?

p.s Nice article, Pat

[Shawn Coyle]

whoever said you can't get ground resonance with a 4 bladed rotor and three wheels should discuss the matter with Careflight - they had the transmission come completely off a 109 earlier this year when it hit a pot-hole...

[John Eacott]

Then there was the 706NAS Wessex scheduled for a tie-down run: chained to the ground run bay, pilot relaxed and comfortable, no need for shoulder harness, right?

Wrong: when the ground resonance finished ripping the chains from the ground, and the stubs of the blades were grinding away into the concrete, with an unconscious pilot in the cockpit, the only way they finally stopped the engine was to pour firefighting foam into the intake. Then they were able to get in and rescue the pilot, who spent 6 months (IIRC) recovering from his injuries :(

[Oracle]

Yup -
The Crabs managed to do the same on a tied down Wx 5 at Shawbury many years back. Their Base MTP sat safely inside as the machine thrashed itself and its chains to teeny bits in all directions (except his, luckily)!

- Even skidded aircraft can get into Ground Res!

[ShyTorque]

Not forgetting the "Pre Northern Ireland shakedown" given to a certain junior pilot in a 72 sqn Wessex by a certain more senior pilot at RAF Odiham some years ago.... :E

[[email protected]]

All you need is unequal tyre pressures on the main wheels as I ably demonstrated to a trapper on an 84 Sqn Wessex in the late 80's. The padding started as soon as I released the rotor brake and, in the seconds it took me to recognise and react by pulling back both SSLs and slamming the rotor brake back on, each wheel had alternately got over a foot clear of the ground. The ground crew were helpfully running in the opposite direction!

[ShyTorque]

Or a bit of slack in an oleo.