Good to be back in the Bay!
Tue, 10 Feb 09 14:29
Well this one comes to you direct from the hot-seat in the container at the Walvis Bay Yacht Club. We managed to duck through the snow storms in the UK and arrived safe and sound in the sunshine and heat of Namibia. There has been very little wind to date... but it shows signs of picking up.
One by one we start the process of 'spinning plates' again. There is a lot to organise.
Here is just a short one to let you know what we are up to and what the plan is.
For those of you who are not fully up to speed, On the 3rd of December, 2008, VESTAS SAILROCKET began collecting records by setting a new 'B' class world record of 47.36 knots over the 500 meter course. This gave her the unofficial title of the worlds fastest boat... but still 3.21 knots short of the Outright world record currently held by the kitesurfers. The team took VESTAS SAILROCKET back to the top of the course with a view to the Outright record. On the following run the craft lost 'pitch stability'. The nose lifted up at near on 60 mph and the shooting match performed a spectacular semi-loop. No-one was injured and VESTAS SAILROCKET was back in action around two weeks later. Un fortunately the good winds required for a record attempt had gone and the team decided to pack up and return when conditions would be more favourable (hopefully now). Around 16 days after their success, the Australian Macquarie Innovations team took the un-official fastest boat title by averaging 48.11 knots. The objective of the VESTAS SAILROCKET project is to get the outright world speed sailing record so they have returned to Walvis Bay, Namibia in 2009 to do this. Every record we get on the way official or un-official is a bonus and enjoyed in the appropriate manner:)
Helena and I arrived back in Namibia four days ago and have been arranging things for our next record attempt with VESTAS SAILROCKET.
We have booked our second WSSRC ratified record attempt to begin on the 20th of February. It will go for 28 days. we have put aside three months in total for the whole session.
We will have a strong team down here as we have seen the benefits of having good people working on all aspects of the project. We need to focus on all aspects of the program during these runs and not just the boat. Our recent success wouldn't have had a fraction of the impact if it wasn't for Helena and Brad doing such a good job of recording the events.
The team at DesignCraft have built a new stronger curved foil which we will fit to VESTAS SAILROCKET mainly in an effort to make the craft safer at high speed and prevent the nose from lifting off again.
We want to have everything in place and functioning perfectly for Day 1 of the record attempt.
So that's about it. I believe that the Macquarie Inn. team is also carrying on with their attempts down in Sandy Point, Australia. Hopefully the bush-fires aren't affecting them. My home town of Healesville is right in the thick of it all and friends I have spoken to today are on the front-line. You have no doubt where your real home is when events like this befall friends and family. Good luck to you all.
So get ready for more thrills and spills party-people because it's about to all kick off down here once more.
Cheers, Paul
perso
Submitted by Stephane on Thu, 02/12/2009 - 14:43.Good afternoon Paul and Helena,
it did not took too long to me to get on the website (we met today at lunch time, I was a bit busy...).
I had a look on the concept and I am very happy to have seen it on site in the WBYC !
Will be here a week more, hope to see you and spend a bit more time to discuss this wonderfull challenge.
See you for a beer in the yacht club !
Stephane
Control-Surface
Submitted by JeremyLees on Tue, 02/10/2009 - 16:54.I have made some very similar comments directly to Paul. I too would want to have active control over the pitch of the boat once it starts to want to lift and become an aircraft. Making the fixed-angle flap on the trailing edge of the beam into a full-on control surface would seem the way to go. However, there's only so much one guy can cope with at one time, so the concept of making the angle of this flap automatically adjusted according to the ride-height of the nose seems very sensible. I suggested that a Moth-like wand might do the trick but Paul reckons such systems are rather 'draggy'...
Anyway, let's hope the new curved foil does the trick and let's all pray for some perfect winds - good luck guys!
Active height control
Submitted by Paul on Sat, 02/14/2009 - 11:35.Hiya guys,
we have considered an active system but it does add a few more issues/complications and complexity to the whole 'big picture'. Obviously it would be a bit of a monty to make it work on the foil as this would require a complete rethink of the foil design, perhaps even moving to a T-foil. That is a pretty volatile solution if it goes wrong and would involve a lengthy design, build and development process... when we are so close to achieving our goals with this one, understand the issues and have a solution at hand.
... So the next option is an active aerodynamic flap on the beam. This is also not such an easy thing to throw on the boat. The mechanism needs to be strong and reliable as we wish to be adding over 30 kg of downforce on the front at full speed. This is quite a lot of force to apply to a system although there are ways of balancing the flap aerodynamically... it gets complicated... and basically isn't necessary. Nothing just builds itself or is simple to make and bolt on. At this stage of the game you have to stand back and look at the big picture. It's time to break records. By simply putting a fixed flap on the beam we keep it as simple as possible and get the guarenteed result we desire. Very little weight penalty, no complications, no development time necessary... just a slight drag penalty at full speed... which can be overcome if we sail in a 'poofteenth' more wind i.e. 0.15 knots more wind.
So, whilst there is nothing wrong with active control, we feel that it is not the best or safest way to progress at this stage of the game. We have approached the pitch instability from three different angles now-
-slightly over canting the foil to allow it to flex into the correct position at full speed.
-added a fixed aerodynamic flap on the inboard end of the main beam to put a downforce on the foil at high speed
-built and fitted a curved main foil which will increase it's downforce as the root of the foil comes out of the water due to the bottom submerged section having more inclination.
I think it's a good safe start. The truth is... that if I had of sheeted in to 10 degrees on that record run... with the benefits of just one of the above... we probably would have done a 50 knot run. The second 'flip' run was done in slightly more wind (a knot or so)... and you saw how aggressively the boat accelerated with the wing fully in. The main flap wasn't even on yet!
We will shortly see. Maybe we are wrong. If so then, just as before with the steering system, we may have to just face up to a lengthy re-design and development process and get on with it.
Stay tuned, it won't be long now.
Cheers, Paul.
Height controll
Submitted by Flemming Rasmussen on Mon, 02/16/2009 - 15:52.Hi Paul
Thanks for taking the time to answer :o)
I fully appreciate your concern regarding introducing new gadgets including new possibilities for errors - my concern however remains in the built in accelerated instability of the system: a smal jump from the bow of the boat e.g. due to hitting a small wave and the angle of attack on the beam is altered - and once lift is created, things goes very fast ;o))
But on the other hand, I'm pretty sure, you guys have a lot more insight in the mechanisms and forces controlling the vessel than a bystander - so: go sailing and break som records ;o))
Sure hope, you get favourable winds during your coming WSSCR period.
An added question: Since you're NOT using a T-foil, how do you avoid air being sucked all the way down the low pressure side of the foil ? I have seen, that MI are using a lot of horisontal "fins" of their foils to prevent that. Here I find it important to distinguish between cavitation and just air being sucked down, as the horisontal fins obviously could not prevent true cavitation.
Regards Flemming
The flying machine
Submitted by Flemming Rasmussen on Tue, 02/10/2009 - 15:18.Hi to the team
I still think you consider an active anti flight control system in stead of of adding more down force to the vessel. As the nose lifting will obviously very quickly lead to an accelerating instability (the lift from the beam increases with the angle of the boat) - all this is clearly verified on the amazing video ;o)
Adding passive downforce is in my terms curing symptoms in stead of problems ? AND will inevitably cause added drag.
If you placed a small lever on the side of the hull attached to a very small planning ski positioned near the front planning surface. This lever should then - when the small planning ski is allowed to drop a determined distance below the planning surface, activate a flap on the trailing egde of the main beam thus creating a regulated downforce.
Further fine tuning of this system mighe even allow you to "fly" the front end of the boat thus reducing the drag slightly ??
Anyway: Keep up the good work guys - I'm pretty jealous sitting here in snowy cold Denmark ;o)
Regards Flemming