the sail was orginally supposed to be 900mm from root to tip. but I had to trim a bit off the tip to get the final rib to fit around the mast.I have not measured it since, Ineed ot make sure the mast is below 110cm from the sheerline…
a big box of straws affixed to your fan would help… not sure if its worth the effort though…
Jim - don’t forget to try it sheeted in. If you are allowing it to just sit there, you basically have the wing in a stalled position, so would be hard to tell based on tell-tales. You could move fan back and channel through a long box which would bring back some directional flow - but for test purposes, your fan shouldn’t matter much at small scales like you are testing. Just fool with the angle of attack, and keep in mind - sitting static there is no apparent wind which will change angle of attack as boat starts moving. One nice thing is you can see what off-wind angle looks good than just a “barn door” down wind.
temp rigged… need to cut a jib… and still work out the flap/sheet boom…
I am working on making a boom that attachess to the bottom of the sail via a ball link and a tunbuckle for ajustment. the hard part is a soft sail is well, soft. so the adjustem can be made the wind will move the sail around and fill it on either side… with the hard sail and flap since the flap and sail pivot is a hard joint the boom has to rotate freely and the flap needs to be able to slide on the boom and pivot from one side to the next for the camber to change… but having an adjustment for the outhaul to stop
I figure if I sheet in on the boom the way I have pictured, check my album, the wind will push on the sail the sheet pulls on the boom and the sail/flap will pivot on the hinge and outhaul… and it will only pivot as far as the stop(fuel hose in this cases) allows it…
to get jmore or less camber. tweak the turnbuckle in or out… so far the simplest way. while not the most elegant it should work…
I’m currently running a drum winch. and I’d love to figure out a way to be able to tweak the camber with the same servo. to get that type of control I may have to switch out to an arm style… but that’s for version #2 if version #1 is successful…
@Marcsmith:
Following this with great interest, thank you for sharing… I am mostly following what is going on I think…
I am certainly no expert so I may be completely off track here; please say so if I am…
It seems to me that you are currently simulating a soft sail using hard material. This is demonstrated by allowing the wind to set the sail fin angle…
I would have thought it would be of advantage to be able to servo control the trailing fin so you can control the amount of camber, just like the aileron on an aircraft wing. If the mast were self-supporting (no shrouds or stays) perhaps the fin control could be up through the centre of the mast. However, this is not available in your configuration.
Just an idea - might it be practical to bring lines from a below-deck standard servo up through the deck on each side of the mast - this line would go halfway up the main wing before going through a loop (near the leading edge of the main wing, not the mast) then horizontally across the face of the main wing to a control horn on the fin (aileron) either side? It would need to be driven both ways, hence the two lines up the mast. Because the turning loops on the main fin are well up from deck level, there should be very little length lost as the main wing is turned.
Hope this makes sense…
in the rg65 class, only two servo’s are allowed… one for sail control, one for rudder…
so yes a micro servo embedded in the sail would work very easily… provided the rules permitted it.
I could probably get some sort of a flexible cable system to operate the flap and if I thought long and hard enough about it. I could probably use the drum winch to do it. but, version 1 has to show promise and performance, before I start getting really experimental…
Marc,
I couldn’t find your album?
Jim.
ready for sea trials…
1235 grams. ready to sail…
final rig weight with all hardware and jib. 185 grams…
my pikanto weight 900 grams ready to sail… soft rig for my pikanto is 70 grams…
jim, i did a cut copy paste when I posted to the rg65 yahoo group. every photo I have posted here I posted there… I juts forgot to remove the reference to that album.
the pic in post 64 is the diagram for my manual flap control…
Aha!!!
NOW I understand… so your problem is compounded somewhat…
There is a solution (actually there are a few) for running a genoa and a mainsail from the same winch - an arrangement such as is used on the Sprinta-RC - there have been a few variations. I have attached a plan of how it works (genoa_alternative). The challenge in that case was to get standard mainsail sheet travel (about 250mm) while providing about 500mm travel on the genoa loop. The only issue with this particular solution was that the mainsail sheet goes slack while the genoa loop travels through centreline. It may provide you an inspiration somehow… if not, well it is only a few bytes of info…
Also attached a sketch of the genoa part of a doublehaul alternative - apologies re foreign language labels (doublehaul_genoa).
Thank you to the authors of these sketches…
Ive seen the sprinta neat boats… I m getting more than enough distance. about 6 " of sheet travel. I could easily double that by adding in a double purchase system. but I don’t have that need.
at this stage of the game. adding the extra complexity of a flap controlled by a servo thats already doing the sheeting is not really warranted, IMO.
I think that I am at the “tweak it” stage, but I seem to keep drifting back to the “build it” stage. Having built a swing rig system, I’m back to a tube in tube arrangement to allow the wing to rotate. I couldn’t make a jib work nicely with the swing rig. A jib was necessary as the only position I could mount the mast pushed the CoE back too far with just the main. The testing is also not going smoothly as I keep running into technical problems. I think that steps 1-3 might take some time to work through.
calling for some wind on saturday. so I may head out to the pond…
I feel that having the jib is needed, I think my CE would be too far aft with just the wing… hence the reason for the wing to rotate around the mast…in my case. make attaching the jib that much easier… if the Ce to too far forwad I can make the jib smaller, or move/cant the rig accordingly…
I do need to get the weight down… if the price was right one of the foam wings would work nicely… but taking off the 6 ounce glass and replacing with 2 ounce might be juts as esy
I’ll be interested to hear how you go. I’m finding the boat a bit tricky to sail with the wing. I’m mostly attributing this to not having the wing quite right yet.
i agree it will take some getting used to… maybe I can talk my dad who will be in town to come out and take some video…
Someone else to take video would be good. Add a third channel to control the flap and taking video by yourself gets pretty difficult.
i can imagine…
Some progress with a revised wing, including controlled flaps:
The wing now rotates around a carbon fibre rod which is held in position by shrouds. The cords to control the flaps pass through teflon tubes that are inserted through the deck.
Testing in light winds:
looks nice jimn.
it was blowing 30 yesterday and only 36* so no chance to get the boat wet… supposed to be even colder today…
Marc,
I visited a friend’s father who is a rc aeroplane enthusiast. Saw a large variety of wings and got some tips for building them. There are some excellent options, and they don’t appear to be too difficult to make. I’m going to visit again to cut a foam wing in a couple of weeks.
Jim.