Firlefanz
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Rocket Man - for real
This guy is doing something really fantastic: He straps on wings with jet engines, jumps out of a plane and flies around at jet speed with nothing but a special suit and a helmet to protect him.
Don't believe it? Take a look here:
Rocket Man at CBS news
--- - Firlefanz
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5/19/2008, 7:40 pm
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QS2
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Re: Rocket Man - for real
Yeah, I heard of him, he's pretty neat and those wings are actually pretty complicated. 
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5/20/2008, 7:51 am
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Firlefanz
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Re: Rocket Man - for real
The video in this link actually shows both the "starting" and "landing" sequence, which is very helpful.
Last edited by Firlefanz, 5/20/2008, 1:01 pm
--- - Firlefanz
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5/20/2008, 1:01 pm
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Reythia
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Re: Rocket Man - for real
Is it sad that only three really fully-thought-out thoughts while watching that video were:
1.) Cool! I want to try that!
2.) Wait a sec. Is that a delta wing? Why would he use something so inherently unstable?
3.) Drogue chute open... And there's the main. (this was concerning the parachute opening sequence)
I'm still debating #2 in my head. Though it was hard to tell for sure what kind of wings he really was wearing, given the lousy film quality.
Thanks for the link, Firle!
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5/20/2008, 4:19 pm
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BaneBlade
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Re: Rocket Man - for real
quote:
Reythia wrote:
I'm still debating #2 in my head. Though it was hard to tell for sure what kind of wings he really was wearing, given the lousy film quality.
Thanks for the link, Firle!
Unstable as in "likely to physically fail" or as in "produces unstable flight"?
I think we all had thought #1 run through our heads. I know I did!
Now all we need are flying cars and a kitchen that cleans itself and those 16mm films I used to watch in grade school about "The World of the Future" will have finally come true.
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...waiting patiently for a few submissions to come back.
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5/20/2008, 4:39 pm
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QS2
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Re: Rocket Man - for real
Isn't that instability mostly due to the center of lift moving as the speed increases? I'm thinking with a human body and the probably highly non supersonic speeds that, that might be a slightly less large concern in this particular case..., correct me if I'm wrong on this though Reythia. 
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5/20/2008, 8:50 pm
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BaneBlade
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Re: Rocket Man - for real
quote:
QS2 wrote:
Isn't that instability mostly due to the center of lift moving as the speed increases? I'm thinking with a human body and the probably highly non supersonic speeds that, that might be a slightly less large concern in this particular case..., correct me if I'm wrong on this though Reythia.
Well, if we're talking about aerodynamic instability perhaps it was intentional. One of the videos mentions that he is "steering" (thier word) by shifting his weight. Perhaps a a wing that was too stable would be hard to steer without mechanical assistance. I also note that I'm not seeing any vertical stabilizers which is consistent with a hang glider (also steered by shifting weight). Of course a hang glider maintains yaw control by having swept wings...not sure about him.
What I was wondering about was what kind of jets he was using. My first thought was valvless pulse jets, as I've seen some plans for modifying hang gliders to use them. However in one scene I can see what appears to be four jets. Given thier size, I'm beginning to wonder. I've not seen many valveless pulse jets in that size range produce more than 20-25 pounds of thrust a piece.
Edited to add: Then again if they were in that thrust range, it would account for having to dive out of the plane. And I note he's flying near mountains, perhaps to utilize ridge lift and mountain waves to aide the jet engines in gaining altitude. (and the wing which is of course producing lift) Meh maybe I'm over thinking this... Time to go to work. No more daydreaming for me.
Last edited by BaneBlade, 5/21/2008, 4:27 pm
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...waiting patiently for a few submissions to come back.
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5/21/2008, 4:22 pm
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Reythia
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Re: Rocket Man - for real
Yeah, Bane, I wondered about the rockets too. Then again, most solid and liquid engines are scalable. I suppose he used something similar to what a light plane would use, and didn't crank it up all the way.
As for the stability issue that caught my eye originally, I've since had time to think about it and I think I was wrong. My original question had effectively been two-fold:
1.) What shape are the wings? They look highly swept-back, possibly even delta-like.
2.) Wait... aren't highly-swept back wings inherently unstable? I think deltas are for sure.
I still can't answer the question to #1, though upon second viewing, I think the wings are merely swept-back, not a true delta (ie: the "plane" doesn't look like one big triangle).
As for #2, I was both right and wrong. Right in the sense that almost all true delta wings are unstable -- they require constant computer guidance to keep them from flipping over and becoming uncontrollable. Delta wings are in "unstable equilibrium", meaning that they fly just great unless they're perturbed out of their happy place -- but if they're perturbed, they tend to crash and burn. Thus the reason they are computer controlled -- it can react fast enough and exactly enough to keep every little breeze from flipping the plane.
However, a quick glance at the ol' aerodynamics books reminded me that swept-wings (the ends are further back on the plane than the root of the wing) are NOT typically unstable. So it looks like my question was moot.
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5/23/2008, 7:25 pm
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