Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by rbanffy on Tuesday June 19, 2018 @06:45PM
(#17350888)
My bad. I should have changed the title. In any case, landing with an engine that can't be throttled down (as most model rockets use), only vectored, will be remarkably challenging unless you can vector it to zero vertical thrust (which I doubt from seeing the components).
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by wcoenen on Sunday June 17, 2018 @03:36PM
(#17333907)
Currently the smallest rocket to reach orbit appears to be the SS-520-5, weighing in at 2.6 metric tons. [1]
I realize that physics is not scale free, and it favors bigger rockets over smaller because a small rocket has a high dry weight (relative to fueled weight), experiences more drag (relative to total mass), and probably other reasons. But I wonder how small a rocket could get and still reach orbit?
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by allenz on Sunday June 17, 2018 @04:37PM
(#17334206)
I think that the physics scales pretty well, actually. It's just that once you get small enough, ground-based or air-based launch systems are going to be more effective than rockets. We're talking railguns, ram accelerators, beam-powered propulsion, and particle accelerators for the really small stuff.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by gnode on Monday June 18, 2018 @01:31PM
(#17340034)
I don't think that's true. When you get to smaller sizes, air resistance becomes the dominant factor. Ground based launch systems would need to impart ever greater velocities to be effective, and the launch vehicle capable of surviving greater frictional wear.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by owenversteeg on Sunday June 17, 2018 @04:01PM
(#17334013)
What benefits in design do small rockets have? Are there aspects of construction/aerodynamics/materials/other effects that get easier when the rocket gets smaller?
(I say this because I'd personally love to see more small rockets reaching orbit, and I'm wondering how that might be made possible)
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by gnode on Monday June 18, 2018 @01:35PM
(#17340070)
The primary benefit seems to be the lower cost / mass producibility. An alternative to making launch vehicles reusable, is to make their production automated and inexpensive. This is a lot more practical when they're on the scale of a family car, rather than a container ship.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by PeterisP on Sunday June 17, 2018 @04:27PM
(#17334170)
The only advantage seems to be if you need to get lots of small payloads into very different orbits, for everything else the square-cube law and other economies of scale work against small rockets.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by jandrewrogers on Sunday June 17, 2018 @02:43PM
(#17333641)
A civilian is allowed to buy a guided missile in the US, even importing it from overseas, as long as they have the correct paperwork and their State permits it (many do); building one can definitely be permissible. Most of the restrictions involved in weaponry of this type are related to storage and handling of hazardous materials, in the same way that you generally aren't allowed to store large quantities of high explosives in a suburban garage even though you (until recently) could buy it by the truckload with a driver's license and cash. There is a hobbyist maker culture of DIY weapon designers in the US that has been around for many decades, typically in parts of the US where it is practical to meet safety and legal requirements.
Many people are surprised to discover that as an American you can buy or build almost any weapon system (if you can afford this expensive hobby) as long as you meet basic safety, local legal, and export restriction requirements. For some types of dangerous weapons you may need to file paperwork, but it is more disclosure than permission.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by vvanders on Sunday June 17, 2018 @02:58PM
(#17333716)
> in the same way that you generally aren't allowed to store large quantities of high explosives in a suburban garage
You can do that with low explosives, you just need a separate, unattached shed, the right license and submit to letting the BATF show up at any time with access to it.
Quite a few of our motor suppliers for the bigger stuff(K/L/M/N) did this, although this was about 5-10 years ago so the laws may have changed since then.
There's basically no high explosives(explodes in open air) used in model rocketry, everything is low explosive(accelerates under pressure), ditto gun reloading and other things that go bang.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by coolspot on Sunday June 17, 2018 @03:33PM
(#17333899)
> Many people are surprised to discover that as an American you can buy or build almost any weapon system
Citation needed.
At very least in CA, NY, NJ civilian absolutely can not buy/build/posses suppressors for guns, short barrel rifles (SBR), select-fire guns, grenade launchers or any live high explosive devices.
In some states you can build a pipe bomb [2] or buy a grenade having per unit permission from NFA [1]
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by jandrewrogers on Sunday June 17, 2018 @04:22PM
(#17334147)
No citation needed, there is no prohibition in Federal law, only State law, and you cherrypicked the most restrictive States in the nation as your exemplars. For example, something like 40+ States permit suppressors. High-explosives was (is? probably with more paperwork now) a retail business in many states; I stopped by one once just to check it out for myself, the only requirement was that I had a vehicle that met road safety requirements for transport e.g. carried on a surface that is not prone to sparking.
I had a couple friends many years ago who, mostly for fun I suspect because they never did anything with it, filled out the relatively simple Federal paperwork that gave them carte blanche to import/manufacture/buy just about any conventional weapon you can think of and they lived in a State with no restrictions. But almost no one does in practice because once you go beyond what is possible to fabricate in a sophisticated machine shop, it would become an extremely expensive hobby for no obvious purpose. Few people can afford to drop millions of dollars on guided missiles.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by vvanders on Sunday June 17, 2018 @02:35PM
(#17333603)
You won't be doing a ton of damage with these, any structural metal pieces are prohibited and until you start getting into some of the larger high power motors, which are not easy to come by, they don't pack a lot of energy.
Over the years in our club we had a lot of land sharks(pop off the rod and delayed ignition), failure to eject, cato(engine explosion) and various RUDs(rapid unscheduled disassembly). Plenty of cars hit with only minor damage and never any serious injuries.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by andymoe on Sunday June 17, 2018 @02:56PM
(#17333706)
There’s explicitly no guidance system. It just keeps the rockets more or less vertical. Been following along with his efforts on Twitter for a year and a half or so. He’s made pretty impressive progress and streams a lot of build/debugging sessions and posts a lot of launch videos.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by Ftuuky on Monday June 18, 2018 @12:00PM
(#17339259)
"The system costs $299, and is only available for sale to residents and citizens of the United States due to ITAR restrictions."
Can someone explain why a toy has such restrictions? Could you actually build a missile using these gizmos? If yes then we live in fascinating/frightening times, where a kid with youtube and some moocs can develop sophisticated weapons.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by foxyv on Monday June 18, 2018 @04:21PM
(#17341387)
I don't see why this would be a problem. Especially considering you can purchase drones with MUCH larger payloads and ranges. Drones are scary when you stop long enough to think about the possible nefarious uses.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by zaarn on Monday June 18, 2018 @04:03AM
(#17336602)
Well, you could do it with a black powder motor if you calculate the burn time such that during the landing phase the TWR of the entire rocket dips below 1 until a descent velocity is achieved and then stays at 1 until landing where you need a bit over 1.
TL;DR extremely (impossibly) hard but not completely impossible if you solve the above problem.
You need atleast a hybrid motor IMO, something where you can control the thrust atleast partially (below and above 1 TWR).
Whether or not you use the same motor for landing or takeoff is another question, you can use the same motor for both if it has enough fuel and TWR.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by trhway on Sunday June 17, 2018 @02:01PM
(#17333449)
not every civilian. If i remember correctly - after reading about amateur launches of like 10ft+ rockets - you have to have some kind of explosive related license to enjoy such rockets.
Re:Vertical Takeoff and Vertical Landing, Now Available for ...
by tropo on Sunday June 17, 2018 @03:35PM
(#17333905)
Not really, though many stores will refuse to sell to you without an NAR certification. You can make your own or just be good friends with the store owner.
The title is a little clickbaity. Landing is not yet possible and it even says so in the article.
I realize that physics is not scale free, and it favors bigger rockets over smaller because a small rocket has a high dry weight (relative to fueled weight), experiences more drag (relative to total mass), and probably other reasons. But I wonder how small a rocket could get and still reach orbit?
[1] https://en.wikipedia.org/wiki/S-Series_(rocket_family)
(I say this because I'd personally love to see more small rockets reaching orbit, and I'm wondering how that might be made possible)
http://up-ship.com/blog/?p=11056
Many people are surprised to discover that as an American you can buy or build almost any weapon system (if you can afford this expensive hobby) as long as you meet basic safety, local legal, and export restriction requirements. For some types of dangerous weapons you may need to file paperwork, but it is more disclosure than permission.
You can do that with low explosives, you just need a separate, unattached shed, the right license and submit to letting the BATF show up at any time with access to it.
Quite a few of our motor suppliers for the bigger stuff(K/L/M/N) did this, although this was about 5-10 years ago so the laws may have changed since then.
There's basically no high explosives(explodes in open air) used in model rocketry, everything is low explosive(accelerates under pressure), ditto gun reloading and other things that go bang.
Citation needed.
At very least in CA, NY, NJ civilian absolutely can not buy/build/posses suppressors for guns, short barrel rifles (SBR), select-fire guns, grenade launchers or any live high explosive devices.
In some states you can build a pipe bomb [2] or buy a grenade having per unit permission from NFA [1]
[1] - https://reddit.com/r/nfa
[2] - https://www.reddit.com/r/NFA/comments/5ffugm/nfa_registered_...
I had a couple friends many years ago who, mostly for fun I suspect because they never did anything with it, filled out the relatively simple Federal paperwork that gave them carte blanche to import/manufacture/buy just about any conventional weapon you can think of and they lived in a State with no restrictions. But almost no one does in practice because once you go beyond what is possible to fabricate in a sophisticated machine shop, it would become an extremely expensive hobby for no obvious purpose. Few people can afford to drop millions of dollars on guided missiles.
Over the years in our club we had a lot of land sharks(pop off the rod and delayed ignition), failure to eject, cato(engine explosion) and various RUDs(rapid unscheduled disassembly). Plenty of cars hit with only minor damage and never any serious injuries.
"The system costs $299, and is only available for sale to residents and citizens of the United States due to ITAR restrictions."
Can someone explain why a toy has such restrictions? Could you actually build a missile using these gizmos? If yes then we live in fascinating/frightening times, where a kid with youtube and some moocs can develop sophisticated weapons.
[1] https://www.youtube.com/watch?v=kTND_wot9zI
http://michael.sdf-eu.org/Gyroc/
With thrust vectoring landing, does it fire another motor when landing?
Do you also need to control the amount of thrust somehow when landing too, with a black powder motor is that possible ?
TL;DR extremely (impossibly) hard but not completely impossible if you solve the above problem.
You need atleast a hybrid motor IMO, something where you can control the thrust atleast partially (below and above 1 TWR).
Whether or not you use the same motor for landing or takeoff is another question, you can use the same motor for both if it has enough fuel and TWR.
A: About half of a civilian owned guided missile.
More details can be found on the National Association of Rocketry website (http://www.nar.org).
Level 1[1], Level 2[2] and Level 3[3] certifications.
[1] http://www.nar.org/high-power-rocketry-info/level-1-hpr-cert...
[2] http://www.nar.org/high-power-rocketry-info/level-2-hpr-cert...
[3] http://www.nar.org/high-power-rocketry-info/level-3-certific...