NASA Whoosh Rocket
www1.grc.nasa.gov
www1.grc.nasa.gov
There are some fantastic model rocketry competitions for youngsters. There is one running in the UK right now (Google 'UKROC') and equivalent ones in the USA, France and Japan. Plenty of guidance is available and it isn't dangerous if you are sensible. We entered a team into UKROC 2 years running and had an amazing time.
[1]Not for some of the developers, apparently. https://mcvuk.com/development-news/squad-devs-blast-kerbal-s...
Only surpassed by the time I tried to grab a falling soldering iron by the tip this is the source of the worst burn I've ever received. I cannot stress how vicious an ignited alcohol mixture in a container can be.
LOL, I can empathize quite a bit, as someone that has a nasty burn scar on my hand caused by a glob of melted saltpeter and sugar from an accidental ignition of a concoction I was cooking one fourth of July in my youth.
Not sure how we made it through our youth without learning what the inside of a jail cell looked like, but I suppose things were different before 9/11.
That was, indeed, an aspect of the problem I alluded to before. I have made it a few times before, and I was going to use the gas grill outside, but it seemed to be acting up, and I didn't trust it, so I thought it would be "safer" to move inside.
Combine that with me iterating on a few different batches with "improvements", such as lining the bottom of the pan with tinfoil so I could lift it out, and then next making an extra large batch... well multiple lessons were learned that day, including how to deal with insurance companies from some shrewd negotiating from my parents, given most the entire kitchen needed to be replaces and the entire house needed to be scrubbed floor to ceiling.
> Not sure how we made it through our youth without learning what the inside of a jail cell looked like, but I suppose things were different before 9/11.
Ha, probably true, especially since my recipe came from a copy of the anarchist cookbook my older brother happened to have (and I wouldn't be surprised if you happened upon it the same way). It's got a lot of dangerous stuff in it, but honestly, as a tool for sparking curiosity it works pretty well.
Please don't post comments saying that HN is turning into Reddit. It's a semi-noob illusion, as old as the hills.
Rockets are fun. With one remaining eye explain to mummy and daddy how this happened again.
We also did some messing around with coke/butane rockets. These could easily knock teeth out and I made my son wear his full face cycling helmet before handling them.
Model rockets with solid fuel motors obviously require an even greater level of respect.
I've never been hurt by an actual rocket motor, but I thought I lost a finger with the woosh rocket that exploded. . . Luckily just a cut and some burns and not on my face.
Once the motor is ignited, nothing will put it out. Not even immersion in water.
The motors are not made to NASA standard and don't always do the expected thing.
Model rockets with solid fuel motors can go 1000s of feet. If they come down in one piece without a parachute (which does happen). You don't want to be under it.
They can set fire to dry ground. I've seen it happen.
None of the above are an issue if you are being sensible, following guidelines and paying attention.
Also: a bad fuel mixture will clog your nozzle with "solid combustion residue", as we called it with my friend, leading to the infamous rapid unplanned disassembly (the motor will promptly explode), so if you value your life and not being in prison, never ever use metal containers for it. Thin PVC pipe dangerous enough in case of RUD, but is much less likely to kill you.
(Obviously, I too somehow survived childhood unharmed...)
The top 3 land use groups were ‘Agriculture’ (63.1%), ‘Forestry, open land and water’ (20.1%), and ‘Residential gardens’ (4.9%)."
https://www.gov.uk/government/statistics/land-use-in-england...
I also seem to recall a type of toy vehicle that was propelled by some compressed gas as it slid, suspended along a horizontal wire/string, but I'm drawing a blank regarding the type of propellant right now. It seemed safe enough to use indoors, especially considering the constrained pathway.
I loved water rockets as a kid and I also enjoyed actual model rocketry, except they seemed too hazardous for me to find a launch area where bystanders felt completely safe. Model rocketry is sometimes 90% modeling, and 10% launching them. Estes can make some really precious designs that fly horribly but look great in a Plexiglas cube on your shelf.
I lost most of the ones I built due to poor launch conditions, and while I chose deserted school campuses during vacation or weekends, I didn't make any friends with security patrols there!
I've heard of using ordinary rubber party balloons for this.
The stoichiometric AFR for isopropanol is 10.4:1 according to the sources I found. For 1g of fuel you need 10.4g of air which at SSL[1] corresponds to around 8.5L. One drop of fuel does consume several liters of air to burn. The volume difference is really that huge --- and the higher the AFR, the bigger the difference; gasoline engines are around 14.7:1, and diesels go much higher when idling or under light load.
Relatedly, fuel economy expressed as an area: http://theskepticalzone.com/wp/weirdly-fuel-efficiency-can-b...
[1] https://en.wikipedia.org/wiki/Standard_sea-level_conditions
I survived my childhood unscarred, somehow.
1. It's only a drop out two of alcohol
2. Carbonated drinks are at a very high pressure already.
I could, if I wasn't feeling lazy right now, do the math to compare the two pressures. Its easy stuff - two drops of alcohol combusted + assumption all the combustion products are ideal gases vs Henry's law for CO2. This last one will require looking up how much co2 is dissolved in the product, but thats not too hard.
But, like the other commentator pointed out.... there's only one way to find out.
https://patents.google.com/patent/US3733309A/en
The patent says they are good to 100 psi for regular operation and people pump them up to 2x that when they shoot them up as rockets.
It's fun to make a "chemical pressure bomb" out of that kind of bottle, the classiest way to do that is to use liquid nitrogen, the second classiest way is to put in a pellet of dry ice, if you have no class at all you put in some aluminum foil and either a strong acid ("The Works" drain cleaner) or a strong base (Lye/Sodium Hydroxide) which in either case will evolve hydrogen. [1]
The dry ice version goes off in 30-45 minutes if you put in just the pellet, if you add some hot water it works like a hand grenade and will explode less than a minute, cold water is intermediate. These are dangerous at point blank range
https://www.youtube.com/watch?v=ZygYNfAKjNs
but in my experience harmless 10 feet away. [2] [3] When I was in college my friends and I made a bunch of them and threw them into a vacant lot at night and thought 30 minutes later that we'd failed, but soon we heard a series of loud explosions which caused the neighbors to call the police. The cops drove by and shined a spotlight into the area and we were worried that the last one would go off when he was there but it exploded just after he drove off.
See also https://en.wikipedia.org/wiki/Boiling_liquid_expanding_vapor...
[1] ... and spray dangerous chemicals. Don't do it.
[2] had one blow the bottom out of a small plastic waste basket though and read a report which I couldn't find this time about a high school chemistry teacher who tried this in class and it blew up in a student's hand, blinding him
[3] usually the bottle is torn up such that most of the plastic is in one big piece with jagged edges, today people would worry about microplastic generation
I don't imagine ANY plastic bottle survives too many lift-offs.
In Larry Niven's Known Space books, rockets are launched from earth using some kind of super-compressed material encased in tanks made of some unobtanium, a vastly improved version of those water rockets.
according to the current laws - it isn't, and may be even more dangerous than walking to the school on your own.
I thought that children walking to school is unthinkable in the US because everything is designed for cars and public transit is inadequate/nonexistent. Made worse by endless suburbia stretching for miles. Someone please prove me wrong...
The hysteria around it is even worse than any of the actual dangers.
Even a sprawling area like Tucson has a public elementary school in each square mile of residential neighborhood. I live in an inner-ring suburb of Chicago (Oak Park) which has 8 elementary schools (plus two middle schools) serving an area of 4.5 square miles. The middle schools require the longest travel distance of about 2.5 miles (taxicab metric). The high school serves a broader region, but that’s fairly typical in the Chicago area but the furthest students travel is about 4 miles (which is a bit less than the commute distance for the most distant students at the high school I attended as a kid one suburb to the south). My own grade school walk was less than half a mile. High school was three miles away for me, and I would get a ride or take the bus in the morning, but often walked home when there was less of a time pressure (sometimes I would walk with friends who lived in the opposite direction from me after school and then back to my own home which made my walk home five miles).
However, if you have a long cardboard tube:
* place the tube vertically with an ignition source at the bottom (small candle perhaps)
* pour fine powder in the top (may need a step ladder if the tube is tall enough)
* satisfying whoosh
Don't look down the tube as you are doing it and don't do it indoors, obvs!
https://youtu.be/aGBT5pwxThU?si=ay9fm_ZaYImIeNK8 is similar to how it was done.
It seems a waste to use rockets and replace the whole rocket or most parts of it after each flight.
This model works with a drop of fuel that evaporates and mix with the air. In a real rocket you most inject the fuel and oxygen from the tanks into the very hot and high pressure burning chamber, so you need pumps.
The reason it hasn’t been done in scale before SpaceX is that reusability is a hard problem to solve and it is/was more economical to use expendable launch vehicles than to develop recoverable and refurbishable stages.
You might also like to read about single-stage-to-orbit (SSTO) which is something of a pipe dream. The rocket equation is a bitch.
That said, refurbishing both the SRBs and the SSMEs after each use was labor-intensive and as such expensive.
The Soviet lookalike did use a single use rocket as its second stage, with the reusable part just being an orbiter.
Sounds suspiciously like one of those projects you propose when you want something finer short term but assume that they never survive to the point where they actually need to deliver?
Refurbishment of the shuttle orbiter took months and tens of thousands of work hours before it could fly again. It was pretty far from what ordinary people understand under "reuse", though not completely outside the meaning of the word.
e.g., the Al-Li metal layer of Shuttle ET was 0.1" thick at thinnest points yet those ET were 150ft+ tall. iPhone back covers are thicker than that. Rocketry gears are infuriatingly flimsy relative to their size, but they have to be because that's what it currently takes to fly to space.
If we could build ships on the Moon from Lunar rocks out of a grinder, or if we could build an all-fusion spaceships, we can (relatively)easily have 2m thick radiation shielding, or 8km wide hulls, or anything we want.
But we're not doing it, but are stuck with lox-fuel chemical propulsion, so we can only make them so durable.
> The common soda can, a marvel of mass production, is 94% soda and 6% can by mass. Compare that to the external tank for the Space Shuttle at 96% propellant and thus, 4% structure. The external tank, big enough inside to hold a barn dance, contains cryogenic fluids at 20 degrees above absolute zero (0 Kelvin), pressurized to 60 pounds per square inch, (for a tank this size, such pressure represents a huge amount of stored energy) and can withstand 3gs while pumping out propellant at 1.5 metric tons per second. The level of engineering knowledge behind such a device in our time is every bit as amazing and cutting-edge as the construction of the pyramids was for their time.
https://ottawacitizen.com/news/local-news/museum-shrugs-as-a...
In service, of course, the necessary pressure would have been maintained by propellant boil-off.
The article never states that the bottle should be made of plastic. Or glass.