So, instead of trying to change the luff, maybe you should be re-thinking the theory – that was a “tongue in cheek” remark, but it did make me think of Bunny Smith.
- Graeme
Graeme, aerodynamic theory is fully understood and proven - at least for the field we are talking about (supercritical flow, very high Ma-numbers and the like excepted). Though this makes wing design a more boring because less adventourous task, it gives us all the tools we need to design an optimal rig - optimal with respect not only to speed and efficiency, but also handling and safety. I see no need in inventing new aerodynamic theories, even more so that the dominating aerodynamic effects on a junk rig are not at all understood yet. We are still fishing in the dark in this respect, speculating about detached air bubbles on port tack, tip vortexes and induced drag, and so on. As long as we can't determine what's happening, and put numbers to it, i.e. xx% drag comes from induced drag, yy% drag comes from distorted profile, it is all just guessing.
That's why I really like David D.'s suggestion of more tufting. Though this won't give us numbers, it will give us a qualitative explanation of what's happening. I didn't take your suggestion as an offence, David! Instead, I might just do it this afternoon :-)
Slieve, I'm with you! It is in fact very interesting to have you as an apparently most experienced aviator onboard this discussion. I envy your flight experience! If my mediocre eyesight wouldn't have cancelled any of my aviation job dreams, I would have probably taken a similar professional choice as you did. Instead, I learned how to design those devices that I would have loved so much to fly myself. As aerodynamics are pretty well understood nowadays, only the exotic issues are being further developed today. For example, in my batchelor thesis I, in cooperation with the DLR, investigated how to increase the laminar boundary layer length on the suction side of a wing using plasma actuators. Though this was highly interesting from a technical point of view, and included me conducting tests in one of the bigger german wind tunnels as well as about 30 in-flight experiments, it was that much high-tec and such an aloofed technique that I would not never consider this as something practical.
Luckily, there is no such medical restriction in sailing! Theory itself is most boring, it is testing in practice where the fun waits.
Folks, I can’t help feeling that you are burning calories on small, and woolly improvement factors.
- Arne
I agree, Arne, that any further improvement can only be in the single-digit procentage range - which will be hard to feel in practice when sailing. However, I can only speak for myself when saying that my primary interest is understanding what is going on at the junk rig. Be assured that I do not mix up understanding with improving. Only after we understand what's going on, there could be improvements developed which are simple enough to be worth it - else it is just plain try and error and may last an indefinite amount of time to get anywhere. Only after understanding, we might consider the cambered junk rig, or split junk rig, or which other design you like, as perfect as it is - or see possibilities for improvements which cost next to nothing but provide advantages otherwise lost.
To clearify the numbers of Ilvy: she has 27% mast balance with 9% camber.
Arne, I agree with all the rest of your points. The high mast balance has proven to be of huge advantage! Especially reefing downwind is amazing. I would not want to miss this point!
However, one more question: Why is a big rudder so important? Would a well balanced CE position give a similar helm characteristic?
Cheers,
Paul
edit: now the same happened to me, Slieve. You and David T. have been faster typers than me! I definitely see your point in questioning the upper fanned panels. One huge improvement on Ilvy could be to get rid of the HK panels and even more so: the THP. If the sail could hang from its halyard sling point, like the SJR, it would need way less lines. Having one less trimline (THP) and no HK parrels would certainly be one further huge improvement - especially in choppy seas!