Dreaming…

[AdrianParticipant]

I hope my interest in this doesn’t slow anybody else down. There’s a good chance that I’m never going to get the round tuit needed to complete the project. It’s fun to think about, though.

Also, my job isn’t much help with this, but I’m picking up some RC glider skills that could be of use. Building and flying different planes gets you into the right mindset.

I wasn’t very clear before, but what I’m looking at would have the wings internal to the rocket, with slots for them to rotate outward. I have looked a little at a scissor wing like the Estes scissor wing transport. That has a simpler 1-piece wing, a simpler deployment mechanism, and a wing that’s nice and symmetric after deployment. The trouble with it, though, is that it’s hard to get the CG far enough forward after deployment, for a rocket with a decent-sized motor. The wing compartment also needs to be almost twice as long as it does for individually-rotating wings that deploy from the back of the compartment. So my fantasy solution is to have two overlapping wings that each pivot sideways. Viewed from the front, the wings wouldn’t be on the same level, but I don’t think that’s a significant problem.

A bigger problem is that with centrally-mounted wings and a symmetric rocket, there isn’t really any natural roll stability for the glide. The autopilot would be a lot easier if the plane naturally trims out into level flight on its own, and all the autopilot has to do is steer it via GPS and maintain a descent rate via a baro sensor. I may be able to curve up the tips a little bit, but not much without running out of room when they’re stowed. Now that I think about it, though, I wonder if the deployment axis could be tilted forward a little bit in the stowed configuration so that when the wings rotate out, they also rotate up to make some dihedral angle. Hmmm.

[BEAR]

If you could have the wings swing out, where they fold forwards and swing backwards at activation and the pivot is at the rear, then you could have swing wings out like on a tomahawk cruise missile. That should solve the stability issue also.

[Warren B. MusselmanModerator]

As I’ve said before, I’m a complete amateur with nothing more than rules of thumb and an empirical approach. I’d very likely take a stab at building a foam wing glider that glides well and then overbuild the shit out of it to take the thrust – say carbon spars, carbon and kevlar over foam wing, etc. Perhaps an aluminum spar for the fuselage. Might take a while to experiment and find the right balance.

I’m not particularly interested in the electronics side or the autopilot issue – just the classic boost, pod pop deployment, wing deployment and then spiral recovery. Just getting something to hold together and cleanly recover would be enough of an accomplishment for me.

[AdrianParticipant]

If you could have the wings swing out, where they fold forwards and swing backwards at activation and the pivot is at the rear, then you could have swing wings out like on a tomahawk cruise missile. That should solve the stability issue also.

I think we’re describing the same thing. I couldn’t find a description of the tomahawk wing deployment, though. Do you have a link?

[BEAR]

I will see what I can find. I can find photos all day that show the slots in the lower fuselage where the wings came from. I used to machine wings for them and saw wing deployment in slow motion from videos a number of times, so that is my source of information, but again, I will find some info and get you a source.

[BEAR]

An update: when I was working on the cruise missiles and I was a machinist cutting airfoils on wings, the wings were folded into the fuselage, swinging forward. At deployment, the wings would fold back into position. In my research last night, I learned this is no longer the case. The cruise missiles of today have wings that swing forward at deployment. When watching a video and researching the tomahawk II, I learned that they are launched out of a torpedo tube. They go submerged a ways to help conceal the location of the submarine. Once they reach the surface, a solid fuel booster fires, the shrouds come away and the tail fins come out for guidance and stability. Once boost phase is over, the booster falls off, the air-intake for the jet engine deploys and the wings swing out. At least, this is the way a number of websites have described it. Accurate information, I do not know. For building a boost glider, I imagine the tail fins are in place for stability and lift. Maybe a canard would be good also to keep the glider from stalling. (Retractable for launch?) Once the rocket reaches apogee, the wings (and canards) deploy for your glinding protion. If the wings were swung forwards, and swing back for deployment, the aerodynamic drag would help deployment, and the mechanism, in theory, could be lighter in weight. The wings would not have to be as strong, therefore not as heavy because they are not deployed during boost phase. I am sure this is all quite obvious to you. This may be a project for the fall and winter when yard work does not require so much time and the days are shorter.

[Bruce R. Schaefer]

Sorry for disappearing, but I had some health issues that kept me preoccupied. The difference between a boost glider and a rocket glider is that the boost glider pops a pod with motor as Warren described. The rocket glider keeps everything on-board. The working difference between the two is that there is usually a mechanical mechanism that moves the CG–with the rocket glider, either the wings swing out or forward to shift the CG. It’s easier to jettison a pod than shift the CG in the other ways. The thing with the Estes Falcon is that as a rocket glider it shot out the motor to shift the CG which isn’t allowed anymore. Even the Predator Drone can use an Aerotech M2500 for R.A.T.O. While I don’t know for sure, I am assuming that the drone has carbon fiber or some composite combination in its wings. If anyone could build a composite wing to withstand any stress, it’s Warren. More on this when I can.

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