Bradfield Foiler NF³ on TWO(2) Foils

This was first posted on "Moth on Foils". I'm hoping that "Busman 1965" will post more details. Like: did the boat takeoff on just two foils? Since it was designed as a three foil boat were there any odd control problems with the centerline rudder foil and lee foil the only ones supporting the boat? Do you have any two foil pictures?
Does anybody else have any experience sailing the Rave with a retracted windward foil or with the windward foil wand neutralized?


[quote=Busman1965;158074]

Originally Posted by Doug Lord

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Part of the big deal is that in 1999 for the first time in history a dinghy was sailed on just two foils. Prior to then dinghies and multihulls had all sailed on foils but a minimum of three foils.


This is not strictly true, when I worked for Dr. Bradfield,in the late 1980's, we made many sucessful flights only using 2 foils, at the time, we were using J foils, with AOA control via the rudder foil. We would tuck up the windward foil, and fly on the leward and rudder foil only. It worked well enough, but was really touchy to keep flying for long periods of time. As a matter of fact, the most sepectacular crash I had, when I owned the foiler nf3 , was on two foils. The boat fell to windward, buried the windward ama, spun and pitchpoled, at about 20knts.......result, 3 broken ribs, both hands skinned to the bone, right leg flayed open kneecap to ankle. Hydrofoils are alot of fun, but non too civilized if sailed hard.

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This is NOT a Bradfield foiler; it is a French surface piercing foiler apparently sailing on
two fols:
foi1_jpg.jpg

[tspeer]

The boat is "Techniques Avancées". It currently holds the D-Class catamaran speed record at 42.12 kt, set in 1997. It has three foils - a forward surface piercing inclined daggerboard foil and rudder T foil on the leeward hull, and a surface piercing foil on the windward hull.

Here's a close-up of the leeward foil in action:

[Busman1965]

Doug,
At the time, when I was working with Dr. Bradfield, and Tom Hayman, we had 3 different foil boats that we were using. NF3, a small foiler made from an 18sq NACRA hull (named Mosquito), and a 21ft foiler (the Hydrosail 21). The first of these boats to fly on 2 foils was Mosquito, if my memory is correct. At the time, all the boats were using the same foils, which were J shaped foils, of a tapered design, which had progressivly faster cross sections to the tip. All of these boats would take off on 2 foils, witout issue. The lift was also ajusted via the dihedral af the foil, thus for less lift the foil was more verticle, and for more lift the foil was more horizontal. They were not ajusted at speed, only when tacking. There was no control system, other than a rudder foil flap, which was usually set for the conditions, and left alone. We found that we kept the windward foil nearly verticle, in most conditions, so we started to retract it , to reduce drag. Neither NF3 nor Mosquito were designed to fly on 2 foils, but we found that they would, quite well. The Hydrosail 21 was designed with bi-foiling in mind. There were no handling problems with any of these boats, when on 2 foils, they behaved about the same as on 3, except for the dreaded fall to windward, in a lull. I remember sitting on the windward tramp of the 21, in a good blow, up and flying on 2 foils, then suddenly being several feet under water, as the boat fell to windward in a lull!
I have a whole box of pictures of these boats flying on 2 and 3 foils, I will have to see of I can find them, and post some. During this time frame, we were primarily looking at foilers for round the bouys racing, with easy beach launching, so the j-foils were the order of the day. We did many races with all 3 boats, using these foils, and had a mixed bag of results. Some were won by huge margins, and some were middle of the pack finishes. We had alot of breakage on the boats early on, but found all the weaknesses and in the end, they were very sturdy. I purchesed NF3 from Dr. Bradfield after I graduated, and raced her myself for several years, she was a nice boat, and a joy to sail, but a handfull to handle, that ridgid wing was a SOB to rig. I always felt that NF3 had the potential to be a world record boat, with the right foils, as the wingsail had much more power than the j-foils could handle....you sort of sailed her by giving her as much power as you thought you could get away with, without blowing her to pieces. In the end, Dr. Bradfield went to the t-foils as they were easier to sail, hence more marketable to the public. The j-foils, with no controls were really interesting, and long flights could be made, but they required alot of knowledge to keep them flying well. I can say that working for Dr Bradfield was one of the best jobs I ever had....getting paid to build and sail fast boats, and break them!

Thanks for the additional info-don't stop now! By "J" foils do you mean surface piercing foils?

[Busman1965]

Yes, they are surface piercing asymetrical foils, hooked at the end. They were designed to be good all around performer, not flat out speed foils. As a matter of fact, I still have a set of them, in my warehouse. They would fly at very low speeds and up to 30kts or so, before ventilating.

[fhrussell]

Was there an Nf2? I remember Dr. Bradfield's first boat in Port Jefferson Harbor, NY when he was a professor at SUNY/ Stony Brook. I used to keep my little 12' outrigger on the beach right next to that monster. I think it used a 20' Tornado hull and had a helm station at the very aft end. It was insane watching that thing whip across the harbor on autumn afternoons.

My father used to have Dr. Bradfield crew for him on his 38' CSK cat. Dr. Bradfield was the one person my father would let borrow the boat...it always came back nicer than when it left.

NF² was a foiler built by Dr. Bradfield in 1975-77 according to James Grogono in "Icarus-the boat that flies". Bradfield captured Icarus' record with a speed of 23 knots in 1978 and according to Grogono "came ashore to change to a larger rig and then went out to take the C class world record with a speed of 24.4 knots". Bradfield is know for the fully submerged foils with wand altitude control systems on the Rave and Scat(and maybe EIFO) but NF² used "ladder" type surface piercing foils.
I'm not sure where NF³ fits in.....
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Tom Speer posted something that I think is important about "J" foils. He removed it for some reason. The gist of the post was that traditionally "J" foils were fully submerged foils. And the best example of the type I can think of are the foils used on the Hobie trifoiler's two main foils. They can be made very strong since there is no joint as in "T" foils.
Maybe he'll post it again.....

[fhrussell]

Thanks Doug! Those dates would correspond... I was a 12 yr old, just built my first outrigger, and launched it Spring of '77. I was in awe of the long-haired students from the university coming down to the beach with Dr. Bradfield and walking Nf2 down to the water. I remember giving a hand once, but really just held onto a part of the craft and walked along. Later that day, I was out sailing my little boat and moving along fairly well, when I hear this 'WoooSHHH' come up behind me and Bradfield is at the helm, passing about 10 yards to leeward at what seemed to be about 5 times my speed...probably was. It's so cool seeing his work appreciated here!

Dr. Bradfield is in Melbourne, FL these days, I believe....?

[Busman1965]

You were wondering where NF3 fit in the pecking order of things. Well, she was basiclly the prototype of the Rave, in many ways. The Hull shape for one, and the general layout as well. She was the first "beachable" foiler, designed for "round the bouys" racing. Also she was Dr Bradfield's first boat with J foils, I believe. The construction of her was amazing, all smooth cold moulded wood, like a sailplane. When I owned her, the City of North Palm Beach accused me of keeping a Glider in my yard!!!! Even better was the time I pitchpoled her in a local lake, and had the TV stations show up, to film the "downed airplane" !!! I discovered that you can pitchpole a foiler very well, I stuffed the bow at about 25knts, and flew from the stern cockpit area, through the wing sail. Needless to say, I came out of the sail with chunks of carbon fiber, and wood splinters sticking out of much of my body.
I still have several large scars on my leg from that day!!! I learned how to reconstruct a wing sail, from that little accident.....

[Man Overboard]

Busman1965

I just had to add some REP points after reading that bit about you catapulting through the wing sail, and living to tell about it.