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FOBS instead of fletchings?

3K views 15 replies 11 participants last post by  Paul Morris 
SPECKDECK (10/16/2007)Very interesting. But, I watched the demo videos and had some questions. He claims that the air moving into the circle moves slower than that on the outside producing lift. I'm no expert, but I do make my living flying, and that statement that he made doesn't exactly go along with the laws of physics. Heavier air on the inside produces lift normally. It could reduce drag. Besides, if the air flow is equal all the way around, how does it lift anything. Stabilize maybe, but lift, I don't know??? Interesting concept though. I'd like to see it in action.
Meanwhile, I'm sticking to the blazer 2 inchers!!! If it ain't broke, don't fix it!
<SPAN style="COLOR: black; FONT-FAMILY: Arial"><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Arial; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto"><SPAN style="COLOR: #111111; FONT-FAMILY: Arial"><P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto"><SPAN style="COLOR: #111111; FONT-FAMILY: Arial">Hello all,<P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto"><SPAN style="COLOR: #111111; FONT-FAMILY: Arial"><SPAN style="COLOR: #1f5080; FONT-FAMILY: Verdana"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p><P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto"><SPAN style="COLOR: #111111; FONT-FAMILY: Arial">I saw there was some FOB talk here so I thought I would join in if that is OK. I promise never to try and sell anything. Just answer question and provide information.<P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto"><SPAN style="COLOR: #111111; FONT-FAMILY: Arial"><SPAN style="COLOR: #1f5080; FONT-FAMILY: Verdana"><o:p></o:p><P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt"><SPAN style="COLOR: #111111; FONT-FAMILY: Arial">My background is Mechanical Engineering. I had spent the better part of 12 years working at a rocket ranch (Hughes Missile Systems). I am also lucky enough to say I have not missed an archery Elk hunt in 25 years. I am even luckier to say it has been with the same group of friends. My thoughts regarding bodies in motion come from crunching the numbers. My thoughts regarding arrow flight comes from hunting and the frustration of getting a broadhead to fly. <SPAN style="COLOR: #1f5080"><o:p></o:p><P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt"><SPAN style="COLOR: #1f5080"> <o:p></o:p><P class=MsoNormal style="BACKGROUND: white; MARGIN: 0in 0in 0pt"><SPAN style="COLOR: black; FONT-FAMILY: Arial">The drag the FOB produces (about the same as a 3 inch fletch)is funneled through the ring wing and is turned into lift (360 degree lift) the ring wing acts like an airplane wing but in 360 degrees. So in effect, the FOB is trying to pull itself apart. It is basically an air gyro. It does not lift the back of the arrow; it provides as much lift up as it does down and side to side. All we have done is taken the drag component and used it for good. A fletch provides drag but that is it. After that it is thrown away (wasted energy). Not to get to technical, but the air that enters the FOB is captured by the ring wing and is compressed by the fins which causes the air to become more dense (heavier) and more efficient. At the last 3/4 of the FOB the air is decompressed which creates extra spin. It is the pressure differential of the air inside vs. outside the ring wing that creates circumferential lift.<SPAN style="COLOR: #1f5080"> <o:p></o:p><P class=MsoNormal style="MARGIN: 0in 0in 0pt"><P class=MsoNormal style="MARGIN: 0in 0in 0pt">Regards,<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="COLOR: black; FONT-FAMILY: Arial"><o:p></o:p>
 
KoolKat45 (12/9/2007)Paul do Fobs work as well as they claim?
Well, I guess "they" would be me and a bunch of happy customers. :) They really do work as advertised. You do need a drop rest that is set up correctly.

The engineering is very straight forward. A ridged airfoil vs. 20,000 year old technology. As bow speeds have increased, the trusty vane has reached its limits. I shoot a large fixed blade Zwickey. As soon as I hit 220 fps a few years back, vanes no longer could do the job. That is why there are so many smaller lightweight (an expensive)heads these days. Its not the speed that is the problem, it is the stabilizer.

Do you use a drop rest?
 
KoolKat45 (12/10/2007)Not using a drop rest now but super interested in Fobs so a drop rest ison the have to have list. What drop rest's do you recommend for Fobs? Thank you for your time and help Paul
What rest are you using now? Are you looking at a full containment rest like the Ripcord or a conventional rest like the Drop Zone or Trophy Taker? Do you use a string loop? What arrows do you have?

soalsrfr (12/10/2007)I picked up a Trophy Taker Shaky Hunter when i was looking at them but haven't outfitted my bow for the FOB'syet.
The TT rest should work great if set up per manufactures instructions. If you use a peel and stick arrow guide, it may need to be trimmed down for clearance. Do you use a string loop? Arrows?

<SPAN style="COLOR: navy; FONT-FAMILY: Arial">I would suggest making a clearance tester. Just take a heavy stock paper or card and cut a 1 inch diameter circle. Then punch a whole in the center. Nock up your arrow and hold the rest in the up position. Then slide the paper disk up and down the arrow. When you get to your rest, hold the arrow in the up position, and let the rest fall. Slide the paper tester over the rest and check for clearance at the arrow guide. I would like you to have about 3/16 clearance.

<SPAN style="COLOR: navy; FONT-FAMILY: Arial">Regards,

<SPAN style="COLOR: navy; FONT-FAMILY: Arial">
 
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