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New Flight Bow

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Marc St Louis	New Flight Bow	Lead	[-]
Posts: 2007 (01/21/11 6:58 AM) Reply Quote More My Recent Posts	Tags : None Remove this ad I had a bit of spare time so decided to experiment on an idea I had a few years ago. I finished the bow a few days ago but at 43# @ 25" it came out a bit lighter than I wanted, I was going for closer to 50#. I tested it out with 275 grain arrows to start and was getting this as an average I went down to a 225 grain arrow and I had this as a top speed, the average was probably in the high 230's. I know the design can do better The bow was self bow of Elm Marc's Bows and Arrows
avcase		#1	[-]
Posts: 587 (01/21/11 8:24 AM) Reply Quote More My Recent Posts	Marc, Wow! That's good. Will Steve be shooting it this year? I hope so! Alan
davidc135		#2	[-]
Posts: 375 (01/21/11 11:50 AM) Reply Quote More My Recent Posts	Marc, Was this bow one of your recurves? Do you have figures for likely energy storage for this design of bow? I played around with the formula that gives virtual mass and guessing the Energy storage at 38.3 ftlbs(?) I came up with 195fps or thereabouts for a 10*25/28gpp arrow. I might be talking through my hat here, but it seems you're closing in on that 200fps milestone. David
fusizoli		#3	[-]
Posts: 1318 (01/21/11 12:23 PM) Reply Quote More My Recent Posts	I've a same paper box here in the shop, just the chrono missed Congrats Marc! Schould we know some datas from the bow lenght and what kind of string U used on this test? http://ijkeszito.yuku.com/ Last Edited By: fusizoli 01/21/11 12:26 PM. Edited 1 times.
Marc St Louis		#4	[-]
Posts: 2008 (01/21/11 2:03 PM) Reply Quote More My Recent Posts	Not this one Alan. This bow was just to see how this design works for regular flight. I will make another that perhaps Steve will want to shoot. It is a recurve David. I don't have any figures for it. I did cheat and used a FF string on it. I'll use a gut string on the next one. The bow is short but I'll keep the actual dimensions to myself for now. Marc's Bows and Arrows
badger5149		#5	[-]
Posts: 4892 (01/21/11 3:06 PM) Reply Quote More My Recent Posts	Mark, that bow could compete very well in the 50# class in case you don't get aroundf to building another one.
Adam Karpowicz		#6	[-]
Posts: 120 (01/21/11 6:11 PM) Reply Quote More My Recent Posts	Marc, this is fantastic - even with the FF string it would be near impossible to make a hornbw that fast, at the low draw weight. I suspect the bow is under 55in long. Congratulations. Adam
redhawk 53		#7	[-]
Posts: 263 (01/22/11 12:04 AM) Reply Quote More My Recent Posts	Marc, that´s great, I bet a lot of bowyers is wracking their brains now, how your bow is looking like. These data will boooooooooooooost selfbowery heavily, selfbow of elm, that´s pure madness! Congrats Marc, thanks for sharing, keep it up, man! I´ll post a link on my blog! Michael
davidc135		#8	[-]
Posts: 378 (01/22/11 2:15 AM) Reply Quote More My Recent Posts	Marc, You've set us all wondering at this bow. Two equations with two unknowns should be solvable. Increasing the Energy stored to 44.6ftlbs and increasing the virtual mass to 120grains would give a better fit for your figures and predict a (best) 10*25/28gpp speed of just under 200fps. But is 44.6ftlbs possible? David Last Edited By: davidc135 01/22/11 2:21 AM. Edited 1 times.
Marc St Louis		#9	[-]
Posts: 2009 (01/22/11 6:52 AM) Reply Quote More My Recent Posts	Steve. The bow is highly stressed and I've probably shot close to 100 arrows out of it and it shows. It started out with about 1 1/2" of reflex and now it's down to 1/2". Another bow would have to be made plus I'm sure I can tweak the design for even better performance. You would be right Adam. I was using a very low brace height, got slapped a few times. I could re-design the handle to get around that, something I was originally going to do anyway but didn't Marc's Bows and Arrows
badger5149		#10	[-]
Posts: 4895 (01/22/11 12:16 PM) Reply Quote More My Recent Posts	Remove this ad My guess would be that the bow is storing about 40# of energy. The shorter draw bows will maintain a higher efficiency with the lighter arrows than the longer draw bows. 40#@ 25" draw is excellent. Only Mark knows the whole story LOL.
fusizoli		#11	[-]
Posts: 1322 (01/22/11 12:59 PM) Reply Quote More My Recent Posts	I think it looking something like this http://ijkeszito.yuku.com/
avcase		#12	[-]
Posts: 588 (01/22/11 2:15 PM) Reply Quote More My Recent Posts	It is too bad the bow is starting to break down already. Is there some adjustments you can make to improve longevity also? Ill join in the speculation with less energy storage is less, but very high efficiency. I guess, 3" brace height, 38 ft-lb of energy storage, and pushing 78% efficiency with the light 225 grain arrow. Was it nice and shock free still with the light arrow? I'm thinking that it probably was. Fusizoli, Great picture, but I am just not sure what kind of elm species that is....? -Alan
Barrage		#13	[-]
Posts: 23 (01/22/11 4:02 PM) Reply Quote More My Recent Posts	Sounds like an impressive bow Marc.
Marc St Louis		#14	[-]
Posts: 2012 (01/22/11 5:39 PM) Reply Quote More My Recent Posts	It would need wider limbs to last longer. As it was I used wood from a small diameter tree and that limited the width of the limbs but this was an experiment. Brace height was 4" but with a redesigned handle I could get it down to 3". Now that I think of it, I didn't notice any hand-shock at all That is almost what it looks like, Zoltan....not :-) Marc's Bows and Arrows
mikekeswick		#15	[-]
Posts: 366 (02/04/11 11:46 PM) Reply Quote More My Recent Posts	Umm interesting. The fastest bows i've made have been short recurves...is it heat treated? Are the recurves longer than normal? Eg. do they occupy more limb length proportionally than 'normal'?
Marc St Louis		#16	[-]
Posts: 2016 (02/10/11 5:34 AM) Reply Quote More My Recent Posts	Of course it's heat-treated Mike. Would you expect anything else from me? Just the opposite, the recurves are short. Here is a braced picture of the bow, the picture was taken just before I started testing the bow. Marc's Bows and Arrows
avcase		#17	[-]
Posts: 591 (02/10/11 9:30 PM) Reply Quote More My Recent Posts	Marc, That certainly has the right look! Is it about 52" NTN? -Alan
redhawk 53		#18	[-]
Posts: 267 (02/10/11 11:42 PM) Reply Quote More My Recent Posts	Thank you Marc for sharing. That´s almost the design I was waiting for. Thank you again for sharing your heat- treating insights too. Meanwhile heat treating is a kind of silver- bullet and a must when making selfbows. I´ve just redesigned and heat- treated an elm selfbow, I did 15 years ago. It had been a real ugly excessively overbuilt bow with a 2" set. But heat- treating makes it a real burner. Do you think that elm is the best wood for heat- treating? I can´t find any scientifical research about that. Michael
mikekeswick		#19	[-]
Posts: 381 (02/11/11 1:25 AM) Reply Quote More My Recent Posts	Funnily enough i've been thinking along similar lines. The deflex should help to keep the inner limb belly wood in near 'pristine' condition, with the outer limb reflex providing string tension at brace and the recurves helping to keep string angle low and energy storage high? Could you give some details on the splice eg. how you cut it to give the deflex. I like!
Marc St Louis		#20	[-]
Posts: 2019 (02/11/11 6:04 AM) Reply Quote More My Recent Posts	Remove this ad Alan: It is exactly 52" N to N. Michael: Elm is at the top but Ironwood (HHB) is right up there as well. In many ways I prefer Elm because it is very strong in tension and doesn't have the ultra fine rings that HHB quite often has. On the other hand HHB is a more elastic wood Mike: The bow started out with 4 1/2" of reflex. I did an article for the Primitive Archer mag on the type of splice I use. It's called a tapered finger joint, the joint not the article. Marc's Bows and Arrows

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