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Re: CD II 10 Dec 2013 21:26 #489

According to this www.homebuiltairplanes.com/forums/soarin...ebuilt-glider-2.html
it is. Unless I am reading this wrong? Just a huge amount of information on this thread. Henryk is the builder I believe. God bless those guys. Looks like they had a blast in the backyard doing the stress testing. The photos reminded me of Dan and everyone when they tested the Carbon Dragon.

--- In This email address is being protected from spambots. You need JavaScript enabled to view it., Kenny Andersen wrote:
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> there apear to be conflicting weight numbers -- I saw 80 Kg somewhere -- I don't think you can do it for 55 KG -- If you can -- I'm in!
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> --- On Tue, 2/21/12, KarlS <kschneider@...> wrote:
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> From: KarlS <kschneider@...>
> Subject: [Carbondragonbuildersandpilots] Re: CD II
> To: This email address is being protected from spambots. You need JavaScript enabled to view it.
> Date: Tuesday, February 21, 2012, 7:43 PM
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> Congratulations Rick on being so close to maiden. You have done what only a few have.
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> About the CD II I also agree that if it is not Part 103 than it makes no sense.
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> It is the challenge that draws me personally.
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> I also believe it would be possible to make the new aircraft with less parts meaning composite structures. Once the plugs and molds are made it would make it a lot easier for anyone else that wanted to build one.
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> Off the shelf hardware as much as possible also. Aircraft Spruce, etc.
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> I would be willing to make plugs and molds.
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> Kenny.. How do you think the Axel is coming in at 55kg? Would it not be possible to do something similar?
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> I have done some composite layups of different things. The weight is in the epoxy. Eliminating gel coats and making the absolute driest layup is the key.
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> Just some thoughts.
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> Karl
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> --- In This email address is being protected from spambots. You need JavaScript enabled to view it., Rick Mullins wrote:
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> > Increasing gross is pretty easy to accomplish by just building a fiberglass spar with carbon rods. You can keep the rest of the wing original if you want. Steve Arndt and Mick Robson both have ballistic chutes that they mounted in the area under the spoiler. They covered the spoiler with fabric so it can shoot through it. In the videos of Steves glider on you tube he shows his ballistic chute installation
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> > I'm going to make an effort to weigh all the pieces of my Eppenauge so that if I do have a nose heavy issue it would be basic math to figure out how far I would need to move them aft to balance the glider.
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> > I eliminated all the foot launch doors on mine and made the pod a little deeper so hopefully I will sit a little farther below the wings an dhave a bit better visibility. I'm thinking I should have mine flying by summer so I'l give a report then.
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> > I'm of the same mind as you. If it's not an ultralight, there are plenty of other gliders out there. I added some weight by going with a composite leading edge, but I lost some by eliminatng the doors. I am going to paint mine (the prototype wasn't) so I'm sure mine will weigh more than 140. Steve's glider is beautiful, but that thick shiny surface added several pounds. I'm going for low weight first, and appearance second, but I may still need the chute weight allwance to be a legal ultralight.
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> > ________________________________
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> > From: Kenny <kennyrayandersen@>
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> > To: This email address is being protected from spambots. You need JavaScript enabled to view it.
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> > Sent: Monday, February 20, 2012 7:13 PM
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> > Subject: [Carbondragonbuildersandpilots] CD II
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> > CD II
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> > For lack of a better moniker, let us start with CD II For reasons oft repeated, maybe it's about time to consider a revised aircraft. I'd like to start with some ground rules of what is necessary (Mandatory), and what are nice-to-haves (optional).
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> > Mandatory
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> > 155 Lb maximum weight, otherwise, you lose the advantage of having an ultra-light. To me, I'm not really interested in a non-ultra-light, since I can buy one of those. Also, there is a new kit that should be out before too long, an HP-24, which sounds pretty cool for a `regular' sailplane. The point is the CD does some things that not many other sailplanes can do, primarily taking advantage of micro-lift â€" I wouldn't want to lose that in a redesign.
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> > Pilot weight 220 Lb â€" probably the biggest beef against the CD is its pilot weight capacity. If it is robustly designed around the 220 Lb 6'2" pilot, then that envelope could be pushed a little and individual accommodations designed into the basic aircraft
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> > Provisions for a ballistic chute; I am not going to fly without one, and I think there is some bonus weight that can be added to the structure. I think you get 25 Lb for the chute and the chute actually is closer to 18 Lb. 7 Lb could buy you an additional inboard rib and some more D-tube (i.e. bigger wing). I like the airbrake/ballistic chute concept just aft of the spar. So, gross weight is up to 180 Lb still meeting the FAR 103 ultra-light category.
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> > Better weight distribution (i.e. not too nose heavy) â€" the CG should be forward of the lift surface for stability, but too far forward and there is too much loss as well as a reduction in pitch authority range.
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> > Nice-to have
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> > Low wing loading â€" I don't know whether it needs to be as low as the original CD/pilot weight, but I think that wouldn't hurt. From what Dan says it doesn't need to be, so maybe it could use the same wing? Or, the option would be to bump up the area to compensate for the heavier pilot. Though, as suggested, that might make hitting the target weight more challenging.
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> > Now, AFAIK no one is foot-launching at 155 Lb, and there is sure to be no one launching at 180 Lb, so I'm for eliminating the whole concept from the plans. I just can't see it provides any useful function and it just adds weight. Car, Bungee, tow, OK
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> > Better visibility...
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> > Design and configuration considerations
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> > With a really light-weight airframe, I think there has to be serious consideration for the wing to be swept forward (maybe leading edge is normal to X axis?) or the pilot more upright or possibly a little of both (for weight balance issues). I think there is less performance impact to the forward-swept wing, assuming it allows the pilot to be more reclined. I think the pilot has to be pretty much right up against the spar. If the wing were swept forward, there might be some change of getting the pilot forward just a bit for better visibility. If the fabric is biased on the 45 it should be very torsionally rigid. I've been contemplating some small internal skin stringers as well as a way to stiffen the skins for stability without adding too much weight. I will have to make a FE model of that to verify.
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> > Additionally, the tail boom should be longer to give more authority and help with the aft CG issue; if you do need some ballast you will need less of it to balance the aircraft.
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> > With a 155/180 Lb w chute weight target, it would seem that the current wing concept of a D-tube with a covering would be retained with an emphasis on weight-saving (ribs, spar). Also, I think that a solid laminate fuselage is simply too heavy, as is fully molded wing skins (ala Axel). The Fuselage needs to be some sort of truss structure with a skin, or it will likely bust the 155 Lb limit. Silly really as it's an arbitrary number and for another 15-20 Lbs you could add some safety. It's the Government â€" what are you going to do?
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> > The canopy would be single curvature for the home-builder â€" maybe something along the lines of the Robin that I posted. I think Mark Calder did a good job with that. It the singly-curving plastic is combined with a composite canopy cover, I think you could get something pretty aerodynamic without resorting to having the expense of a blown canopy. Also, remember that the CD forte is slow-speed, so there is less of a penalty associated with a less-than-perfect pod. I think as long as it's clean, it should be good to go.
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> > I think there is also not much change of making a constant section wing and meeting the weight targets unless you are willing to sacrifice significant performance (i.e. trading some external bracing etc. for weight, which will increase drag).
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> > Maybe the wing could be the same size, but some winglets added to bump the efficiency up a bit?
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> > Anyway, just some thoughts

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