Edward,  off course I had you in mind, having much enjoyed all your reports.  All needed is to encourage others with different JR rigs to enter. 

I agree with the earlier post, that a small dinghy or similar is no the best test bed.  It should be on the typical sort of yacht most members use, in the typical sea conditions, though this does make match racing two similar boats with different rigs too expensive.  

I think the best way forward is to enter large open event, such as the RIOW, where there are standard boats of the same class.  The then gives a comparison of how the JR PY rating differs from the standard pointy rig.  With sufficient data this will give a method of establishing a comparison between JR rigs on different boats.  It would need the commitment to enter a few events to gain a good average.   If the JRA could provide some financial sponsorship, I would be in favour.  

Bryan Tuffnell wrote:

  Any decent wind tunnel allows pitch, roll, yaw, heave, surge, sway, AoA and velocity changes, including rate changes; that's their role. Dynamic testing in a tunnel is intended to give results whereby the variables are reproducible, controllable and quantified, free from the noise and scatter that plagues 'real world' testing in an unstable environment. 

Most engineering universities seem to have a suitable tunnel, and there's usually enough students looking for a project to generate more help than is needed! I've never paid for tunnel time, even when using one for commercial purposes.

You make a very interesting suggestion. You clearly have the experience to supervise such a project. Would you be willing to take it on, i.e. to supervise the student(s)?

I was of the opinion that renting a wind tunnel would be prohibitively expensive, but if we can persuade a student to do it for us as part of their degree project, then it potentially becomes very economical.

Although the points raised by David & Slieve about real world conditions are very valid, it would still be very interesting to have well documented lift and drag curves from zero to stall for the various rigs developed since Joddy Chapman's MSc. I think that would not need an MSC student but would be suitable for an undergraduate final year project to test, for example, a flat junk, a cambered panel junk, a bendy and/or hinged batten junk, a split rig junk, an aerojunk, and a wingsail junk, i.e. up to 7 different types, and possibly more. The tunnel needs to be as big as possible to minimise the scaling issues.

Even stable airflow tests would be worth doing, although if we can get dynamic testing as well, so much the better. Making these undergraduate projects will lead to shorter reports! As we have seen, MSc's create meatier tomes than we really want.

Naturally I think a wind tunnel programme should happen in parallel with real world instrumented testing as originally proposed, especially if it is effectively free, as Bryan suggests it should be.

Slieve McGalliard wrote:

Hi Bryan,

I don't know where you can get a large cross section wind tunnel very cheaply as it wasn't available when I researched that avenue some 10+ years ago. A tunnel may give accurate measurements, but they would be useless for comparing rigs as they would be static results, and small junk rigged boats are anything but static. It would be necessary to include dynamic performance with stall recovery an important consideration to be of any use.

Any decent wind tunnel allows pitch, roll, yaw, heave, surge, sway, AoA and velocity changes, including rate changes; that's their role. Dynamic testing in a tunnel is intended to give results whereby the variables are reproducible, controllable and quantified, free from the noise and scatter that plagues 'real world' testing in an unstable environment. 

Most engineering universities seem to have a suitable tunnel, and there's usually enough students looking for a project to generate more help than is needed! I've never paid for tunnel time, even when using one for commercial purposes.

I won't labour the point any further.

Hi Bryan,

I don't know where you can get a large cross section wind tunnel very cheaply as it wasn't available when I researched that avenue some 10+ years ago. A tunnel may give accurate measurements, but they would be useless for comparing rigs as they would be static results, and small junk rigged boats are anything but static. It would be necessary to include dynamic performance with stall recovery an important consideration to be of any use.

Unless the measurements are taken in the same sea state at the same time they will be of little use, so you always come back to direct boat on boat tests. There is really no way to ensure that tests repeated even on the same rig/ boat combination on different days will produce consistent usable results, which would be usefully compared with other rigs measured elsewhere

Cheers, Slieve.