Donald Campbell's restored Bluebird in museum home row

[captain sparkle]

That'll be about 1m 04 secs? then?
You are Chalkie White & i claim my prize!

Great stuff Bill! keep it comin'!

[Renegadenemo]

That'll be about 1m 04 secs? then?

Nope, the brake goes down at about 54 seconds. Note the twin rooster tails as the water is cut by the ram descending below the rear wedge. Look at how much water is in the air, literally tons of the stuff, and imagine just how much energy is being torn out of the system as that happens. I remember having lunch with Lew Norris. Ken was the dreamer, Lew was the cautious thinker. He told me two things. That the boat was way too efficient when up on the plane - we proved that out because the damn thing just wouldn't come back down once we got her up on her points. And that the water brake was equally efficient and violent - we proved that out too when Ted almost went through the canopy on its first deployment.


Sooner this dangerous machine is locked away in a museum to gather dust the better!

[captain sparkle]

aaah! Thanks Bill, I stand corrected.



Never did find that Chalkie White, on Morecambe prom, with his Daily Mirror!

[Chris Williams]

Bill - I know from what I've read that the thrust line from the jet engine produces a turning moment around the centre of gravity which applies a downward pressure on the bows helping to keep her nose down. What effect does the water brake have in this context?

[longarmedgibbon]

Intresting what you say bill about k7 taking ages to come down of the plane, the exact same thing happens with my dads,ernie lazenby, big gas turbine model, it takes 8-10 seconds to come off the plane when i shut the power down ,on the short you tube vid ive attached i shut the power down at 0.13 and it settles back in the water at 0.21

https://youtu.be/mJYAz7wHZjY

[Engine 711]

Bill - I know from what I've read that the thrust line from the jet engine produces a turning moment around the centre of gravity which applies a downward pressure on the bows helping to keep her nose down. What effect does the water brake have in this context?

Believe the Water Brake also generates a turning moment, tending to push the bows down. It is located behind the rear planing 'shoe'.

Not entirely convinced myself....

[Engine 711]

Intresting what you say bill about k7 taking ages to come down of the plane, the exact same thing happens with my dads,ernie lazenby, big gas turbine model, it takes 8-10 seconds to come off the plane when i shut the power down ,on the short you tube vid ive attached i shut the power down at 0.13 and it settles back in the water at 0.21

https://youtu.be/mJYAz7wHZjY

Believe K7 was known to 'float' or 'hover', once up on its points - and actually went faster, as it did so - even without more engine power being applied.

Think I have read that DMC's method was to get it up on its points, then back off power, and let it plane through the Measure Kilo. Only what I have read....

[Richie]

I believe the brake would cause the nose to dip, by adding a retarding force to the rear of the boat which the boat will then rotate around, however, the rate at which it brings the boat down is anyone’s guess... the more of the ram that enters the water, the more single point drag = greater rotational effect.

Bearing in mind on the hoof she has three points of contact in the water all with a very low drag coefficient, shove a big wedging bar into the mix (read that as brake ram) and you suddenly have a large single point of drag..... I bet the Delta-V figures are interesting when the ram is deployed at planing speed !

It could be calculated I am sure, need someone smarter than me to do it though.

[Engine 711]

Briefly (re)reading the last chapter (10) of Neil Sheppards book, on K7 and there is speculation on what effect the Water Brake might have had - if deployed, on the last run, 4th Jan'67. The conclusion was that in the hovering or floating state - its unclear what would have happened.

Ken Norris is quoted as telling DMC, that the Water Brake should not be applied above 200mph.

On The Hoof is new to me, but I follow. The Water Brake I think was intended to ruin the flow around the Rear Shoe, which the change in the Rooster Tail shows it still does, very effectively. But - K7 still needs to drop down.... Which it doesn't seem to do in a hurry. Perhaps why Ted was steering away right at the end of his last run..... Before it finally dropped down.

[Renegadenemo]

Briefly (re)reading the last chapter (10) of Neil Sheppards book, on K7 and there is speculation on what effect the Water Brake might have had - if deployed, on the last run, 4th Jan'67. The conclusion was that in the hovering or floating state - its unclear what would have happened.

Having seen how violent and effective the water brake is by resurrecting it and actually using it at speed I'd say there's little doubt that had Donald been able to fire it down as his 4th Jan event developed it would have slammed the nose back down, likely destroyed the main spar fairings and blasted a ton of water into the sponson tops whilst pulling his eyeballs from their sockets with the deceleration forces and the front end would have stayed firmly buried in the water until way below any speed where the boat would have blown over. Pretty much all I know about the theory of the water brake I learned over lunch with Lew Norris and much of what he told me he never had answers to because it was never really tried, the rest we learned by making it all work again from a pile of scrap parts that lay rotting on the bottom of a lake for 34 years so to see everything Lew envisaged proved correct is a real thrill and very satisfying.