The 53 knot 'Boost' into the blue !!!

I'll cut to the chase...

Yesterday we did a run in gusty conditions with recorded winds during the run ranging from 18.6 to 26.3 knots. The run started slow and peaked at 52.8 knots going past the timing hut... with no main flap on (approx. 4 knots still up our sleeve)... I got the flap on and pushed on trying to make this run count. At the end of the course we hit a small freak wave (a last remnant of the North bound Atlantic swell that wraps around the distant Pelican point and rolls back up the bay). The front end got 'boosted' and it appears that the main foil failed at the top inboard tip due to the centre of effort moving rapidly down with the boat fully loaded at around 48-50 knots.

 

It didn't go as high as last time and turned 90 degrees to leeward... but it did the full flip and inverted landing. As I sat there looking at the clouds I congratulated myself on my choice of full-face KBC helmet and HANS neckbrace. They absorbed the impact well as my shoulders smashed the 'roll-bar' clean off as I flew out. I was fine.

At that stage I thought... "That's it... no more. This boat has issues". I thought the boat had just lost pitch stability in a gust. Alex pointed to the main foil which was wobbling around in the air. I was quitely relieved. Component failures are easier to resolve. The upturned boat was dragged backwards to the shore with the wing dragging alongside trailing bits of broken flap.

 

Once we got it ashore we could do a basic damage assessment. The boat itself is  undameged... amazingly enough... neither is the whole main section of the wing... or the two end flaps!!! Even the strut is still intact. The main flap is confetti and there is a few spots of random damage that will take some detailed repairs. We got the boat back last night and brought the wing back this morning. We've already started. This boat has had a hard life... perhaps the hardest of all(considering it is the same hull/beam and wing originally launched)... but it just refuses to die.

 

We've gone over all the data and watched all the videos. It was only on the video that we saw the wave. The peak speed was actually done earlier where we did 5 seconds over 50 knots. The sun was glaring of the wing angle display. From the PI/COSWORTH data logger I could see that I could have sheeted in a little more and as mentioned, still had the flap to come in. The wind was measured at around 25 knots there so it's not surprising. The video showed how solid the front end of this boat is in normal conditions. To me it didn't feel like anything super special. If only the wind wasn't so damned gusty! This boat has a world record in it and we are going to do every thing in our power to drag it out.

 

We will go through the foil failure and work out a repair. Obviously  it didn't have enough of a safety margin. The foil itself is fine... it's only the very top tip where it is supported by a ball joint at the top of the centre-board case. So we found another weak link that may have let us down at a higher peak speed with even more drastic consequences. Looking at the damage now I feel that we got of lightly.

 

Of course we caught it all on video with stills from both directions. I even had an onboard camera... which turned itself off the second the nose lifted (I will write a whole report about onboard cameras for boats as no-one has got it right. We've tried them all and spent thousands... and they all fail or give average results).

 

It will take us 7-10 days to be back in action. The boat will be better than ever and we remain undeterred. we know this particular boat is far from perfect... but we also know first hand that it is bloody quick and that on its day it should be able to top Hydroptere's current record. I will happily climb back onboard. One day, just as it has for every other world record holder that has had the perseverence, it will all come together for us... and it will all seem easy. 

 

all the goodies will be posted once we sort out our other job-list.

 

Perseverence pays.

 

Cheers, Paul...

 

  

Comments

On mods and design...

Hi guys... I always like reading the comments just to see how it looks back a bit from the coal-face. Meanwhile... at the coal-face here, I am surrounded by whirring generators, grinders and my feet are resting on the buzzing vacuum pump which is sucking down one of the new main flap sections. Outside walvis Bay is goading us with a perfect record breaking day!!! We need faster resin damnit! I have to say that of the comments so far, I would have to agree with Johan. Events to come will humour him no doubt. Even an active flap control would not cure this boats problems... especially as the last crash was mainly caused by a foil failure and hence a total loss of downforce. It would take a big beam flap to react the whole wing. The concept could work... and it could be an improvement. It has been considered. Brad has seen firsthand how long it takes to develop these systems to a point of total reliability. They need to be totally reliable  at the speeds we are going. If they aren't... then they are dangerous. If we had designed a feeler arm out the front... it would have probably only added height to the 'boost' off the wave as it would have hit it first and added a lifting force. Depends on how we designed it of course... but just a thought... and something to consider later if we do incorporate such a system. Video to follow soon...ish!!!

Cheers, Paul.

foil failure

First I'm not laughing at anything Paul, I'm still admiring what you have achieved. Just giving my view of the concept that I've been puzzling about for quite some years now.
The model could handle loss of grip of the foil because for some reason the beam didn't take the front end in the air. I think it was because the model was so light that the bow could jump leeward alowing for the amount of lift in the beam to decrease very rapidly and the sailforce also.
So if you only manage to keep the beam from lifting sailrocket and keep the boat strait I see no reason why Sailrocket would behave different from the model and stay controlable even after a foil failure. They way to do it is to bring the cg in front of the cl and bring the foil at the centre of lateral resistance the boat would have without a foil e.g. in the middle. The rudder must not spoil this centre of lateral resistance so an air rudder is best.
I'm quite sure the boat will be controlable then even if the foil brakes. Compare it to a spinout on a windsurfboard: There is only one fin that is slightly behind (so not even optimal for this purpose) the center of lateral resistance so the board remains controlable.
And if you have the beam and the foil in the middle and the pilot in front of it all the weight is more central making sailrocket faster. This holds true for every boat.
But this requires a new mainhull for which you don't have the time. A few more knots more is within reach with sailrocket as it is now but if you want to go beyond it I really believe a basically stable boat is the way to go.

Good luck again !

Bad luck

This is just bad luck indeed. Good to hear Paul is alright again and the boat is reapairable.
With more luck the foil keeps on having grip and you get the record.
But Sailrocket is depending too much on that foil. Two forces battle with eachother in de front of the boat, the lift of the beam and the downward force of the foil. If the foil looses grip the beam wins every time.
Giving Sailrocket active lifting foilcontrol is a solution and making the beam neutral is a good idea but at a certain angle the beam will never be neutral. If the lifting foil looses contact for whatever reason, also structural failure, Paul will again be flying.
I still believe it's beter to make the boat inherently stable, no matter if the foil has grip or not. It makes Sailrocket much safer and also faster. It's best to bring the normal foil and the beam back and bring the pilot forward, so you have the cg in front of the centre of lift. And then you can suffice with one normal foil and one rudder of even better one normal foil and an air rudder. With lifting foils you always need two or one in front and at the back a planing surface which again when the lifting foil is braking or loosing grip will cause dramatic crashes. A problem with active lifting foils is that they always create lift AND lateral resistance. A planing surface doesn't.
Working towards a boat that is also controlable whithout a foil is the best way I believe, it's the safest and because it's the best balanced also the fastest solution.

Good luck with the repair and the record, if the foil stays intact you will get it this time !!

Cheers,

Johan

perserverance , " "

Good luck to you all in staying focused driven and posative, It`s so close that im getting goose pimples X 1,000`s of miles away.I wish you all the very best of luck and shout for thousands "Go team Vesta" ,..and thank you !

53k a7 Airborne

Paul, do you actually inform Air Traffic Control when your about to set off?

To fasten the seat belt do this.....
Exits are here & here, remember the nearest exit may be behind you.......
Tables & chairs to the upright position.

Wandering Bear

Active control

Hi Paul

Sorry for the set back. I will again suggest active controll of the flap on the main beam. If you want to play it safe WITHOUT this, you will have set the flap rather conservative - obviously more conservative than for this run - and thus create unnecessary drag - and not least downforce on the front planning surface.

With a active control with a small planning ski controlling the flap angle, you could actually safely "fly" the front planning surface with less drag from as well the beam as the hull.

You have not really mentioned your plans after Sailrocket MK I, but I'm pretty sure, a new project is in mind ? ;o)

Regards Flemming

P.S. Good luck with the remaining of the WSSRC period.

active control

Hey Flem, this is a 30 day WR attempt. They'll get this boat banged up ASAP and get it back on the water and do it all again. All they need is a little luck and the records is in the bag. I'm not saying your suggestion is crap, its just not practical. At 50 kts, you need the least amount of moving parts as possible, (the boat being the only exception). this boat has tried so many mods and control devices, i've lost track. Like i said, its bang on the money now!, is just luck that is elluding them.

Active

Hi Brad

I do agree, that there is a time window here - thats the reason for my question: What comes after this WSSRC attemmpt ;o).

I do however not agree, that the concept is too complicated to implement. Almost all sailing boats running on foils use the system to control the pitch of the horisontal part of the foil to get the proper "flying height" - It does not have to be very complicated - could be integrated as a trailing egde of the front planning surface with a small pin connected to the already existing flap on the main beam - and as mentioned earlier: With the proper trim, the front planning surface could be kept flying a few inches above the surface, using the beam as an aerofoil, rather than using hydrofoils.

Alternatively lose the aerofoil design of the beam completely and use a hydrofoil on the main foil for (non)flight control.

No matter how you look at it, its at matter of at lot of luck, as the system is dead unstable. Any insignificant lift of the bow will create a highly enforced negative feed back into the system. I have a background as an engineer in regulation techniques - and the current system is the definition of instability.

I know it is always easy to sit at a distance and be a smartass, but I too have followed this project right from the start and there are so many good ideas in it - and I am sure that if not this version will beat the record, the next one will.

control

Flemming

 

basically what we have is a stable zone within a wider grossly unstable zone. Its  like riding a bike on a curved wall with a slightly dipped top.  We now are pretty confident we can stay on the flat/dipped top if nothing breaks and the goal is within sight.

No practical control system will deal with foil failure - sudden loss of 0.4tonnes vertical down force!.   It possibly could allow recovery from a smaller disturbance but since we changed the main foil shape and angle there is nothing indicating we need it.

 

Malcolm Barnsley

Control

Hi Malcolm

Thanks for elaborating, the description of the (slightly) stable system makes very good sense. However for the next design, I would still consider thinking about regulating rather than balancing ;o)

I was not aware, that a failure in the foil was the cause of the latest back flip - obviously, I did not read the post good enough - sorry.

Anyway: I am confident, that the goal is within reach, so patch her back together and go get 'em. :o)

Regards Flemming

website by hangmyhat