Archive of the Yahoo! Groups mailing list for the Bug hand-launch glider 2002-2018

From: "maxddnj" <maxdd76@...>
Date: Saturday, March 24, 2012 10:38 PM
Subject: Re: Carbon Booms - Goodwinds
Hi Guys, I'm confused by the recommendations for SkyShark P90 and P100. Here are some weight comparisons of P90/P100 to standard recommended 1/8" pultruded CF tube. All the same lengths and all sold by Goodwinds: SkyShark II P90: length 32.5, OD 0.275", weight 10.5g SkyShark II P100: length 32.5, OD 0.280", weight 13g Pultruded Light wall: length 32.5, OD 0.125", weight 6.3g Pultruded Strong wall: length 32.5, OD 0.125", weight 7.2g I actually ordered a few of the P90 and P100's, they arrived today and look amazing but will I be able to use them in a Bug? They almost double the weight of the recommended boom and spars. Will today's lighter electronics make up for this or is this going to smash my Bug to splinters on maiden launch? I haven't started building yet so I could always save these for future projects and stick to recommended sizes and just go pultruded 1/8". Are you guys actually using P90 and P100's in Bugs or other larger kits? Thanks, Max --- In BugHLG@yahoogroups.com, Tim Schuh <tim@...> wrote: > > On 3/21/2012 2:31 PM, raincityflyer wrote: > > > > Make sure you are watching your weights with "retail" CF parts. The OD's may match, but the wall thickness is what kills you. > > > > The final version of the Little Nipper (Swyft 2) uses a wrapped spar and is really stiff. I opted to go this route to fight the flex you get in a pultruded spar. This flex takes a lot of height out of your launch as the wings oscillate up and down after release. The arc can be pretty dramatic. > > > > Same goes for the boom. The whipping oscillation deprives you of launch height as the tail wags back and forth. > > > > Carl designed this plane for a javelin launch with no torsion to the boom. Wing flex was also just a given in those early days. > > > > The LB will work with any combination of CF parts, just watch your weight. As they say - "Ounces are made up of grams." > > > > Stay light! > > > > Chris in Seattle > > > > I can vouch for the P100 fitting into the new AG37 wing, so don't be afraid to try it. > > > I agree with Chris. I've used P90 and P100 tubes on my 1.2m and 1.5m > woodie DLG experiments without any issues at all. In fact I used a P100 > on a 2M woodie floater pod and boom with good results. There's plenty > of stiffness and much lightness. For a quick, very informal comparison > here's what I have on hand and within reach. I got all the CF tubes on > sale and I don't think I paid more than a few dollars for any of them. > I know I got a mess of them for less than $20 shipped to my door in Texas. > > All tubes are 36" long. > > Generic fiberglass pushrod tube (I think from a Dave Brown pushrod kit) > OD: 0.300 > ID: 0.241 > W: 22g > > SkyShark II (no other markings and I don't remember) CF tube: > OD: 0.387 > ID 0.345 > W: 17g > > P90 tube: > OD 0.280 > ID .0240 > W:11g > > P100 tube: > OD: 0.285 > ID: 0.240 > W: 13g >