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back to article LOHAN seeks mighty thruster for trip to heaven and back

Our Low Orbit Helium Assisted Navigator (LOHAN) project is beginning to gain momentum, and we reckon it's about time we looked into the explosive matter of the Vulture 2 rocket motor. Click here for a bigger version of the LOHAN graphic Rather handily, a large number of experts in the field will be gathered in Scotland next …

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Anonymous Coward

Qassam

Take a tip from these guys: http://en.wikipedia.org/wiki/Qassam_rocket

I'm sure it can be adapted for the lighter payload. Nice n' simple, weedkiller and sugar mix and as big as you want.

Off the shelf motors will be small....

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Boffin

Not really

You'd need something that will burn (and more importantly ignite) in a partial vacuum. That probably means an off-the-shelf ammonium perchlorate composite propellant (APCP) rocket, like those made by firms like Aerotech.

The main problem, then, will be to find an APCP blend that has sufficient thrust, for a sufficient burn time. Common long-duration mile-high-plus rocket motors like the Aerotech White Lightnings, generate about a five to seven second burn - initial burn of over 300 pounds of thrust for the first half second, followed by a sustained 80-odd pounds, thereafter.

White Lightning is favoured by those who like to follow their rocket during the ascent, but most people aiming for mile-high and more altitudes opt for extremely powerful, short-duration engines like the Redline or Blue Thunder (under two seconds burn) because sheer speed is better than a long burn. Each second spent burning, is another second spent fighting gravity, so the most economical means of gaining altitude is actually to just get there as fast as possible. I would guess that standard launches like these would tear both the plane and the gondola to pieces, in this instance, however.

Even with six seconds you need to be doing an average of 80 meters per second squared to do more than a mile of powered flight.

Slower burning types, like those used in model planes will probably not ignite and burn under these conditions, because they are air-burners. They are also tailored to the needs of devices that can generate lift via aerodynamics: i.e. they wouldn't produce any meaningful altitude gain, even if they could burn.

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Angel

I think....

....you pop up to Scotland...

(From where I live, it's up to Aberdeen, through to Perth, across to Glasgow and down to Edinburgh - oh, and in to Dundee)

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Boffin

up, down, left, right

I too usually say 'up to' for places north of me and 'down to' for places south. Not sure why. Why is North up and South down? Not everyone follows that though.

Then again the Mainers here on this side of pond like to think of themselves as "down east." Then again, the fact that they're from Maine says a lot.

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Anonymous Coward

Going up....

A rather older convention in the UK is that "Up trains" go to London.

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Facepalm

Well.

...luckily I have no need to cross the border...

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Silver badge
Boffin

Why is North up and South down?

I've seen many old maps where Up is South, East, west, or even some fairly random direction. North up is mostly a convention that stuck, although I suspect it's also linked to the fixed position of Polaris above the north pole (a lot of old maps combined star charts around the edges). In Australia and New Zealand it's possible to buy 'upside-down' maps.(which look disconcertingly weird), though more of a novelty item. And speaking of mapping conventions, we Europeans (and Americans?) are used to the convention of splitting world maps down the pacific, which places Europe centrally, while world maps I've seen in China split down the Atlantic, putting China in the middle. It's amazing how different / weird these maps can look just because they are different from what we're used to.

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Boffin

NASA/ESA worthy complexity

Re: that video. If you can pull off a plane that loops and fires the rocket at the right time, I'll be majorly impressed,

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Simples....

Well, relatively.

Getting the "plane" to do the loop bit is a simple case of aerodynamics and weight distribution. Getting the rocket to fire at the right attitude can be accomplished with a a bunch (3) of mercury switches.

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Headmaster

But...

There are no aerodynamics, at that altitude, which is why the launch shown in the video could never occur. Nice video, though.

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Title

Brings Blackadder to mind.

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Flame

Rocket motors

I seem to remember that anything over a certain size (D?) in the UK needs an explosives license, with a specific license for anything other than buying to directly transport & use on the same day. Which lucky sod gets to walk into the local ploddery & ask for the application form, or is 00-Lewis fully licensed for things that make you go boom?

Flames coz, well, boom.

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Pint

One more time

I said it before, and I will say it again. To be named LOHAN it must be alcohol fueled.

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Silver badge

Rockets

Quick question...

Is the lovely LOHAN going to have a tailpipe rocket or tractor rockets? I was thinking (rare I know) that if you used tractors on the end of a long - erm - I'm sure there's a technical name for this, but let's just call it a - stick, with the plane at the far end you might be able ensure the plane is always pointing up and clear of the balloon simply by adjusting the fulcrum about which the plane is suspended so that the rockets always point up and the plane hangs down.

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Boffin

The Pendulum Rocket Fallacy

You may wat to look it up. It goes against common sense but it explains why your suggestion won't work.

Also, sticks on fireworks and the like work by aerodynamic forces. With so little air at those altitudes they'd be no point having one.

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High Power Rocketry

It's good that you're going to the Scotland rocket event. You will undoubtedly encounter a niche in the rocketry hobby world, High Power Rocketry. I used to build rockets when I was a kid, back then, E F and G rockets were considered the top end, I recall building a small 2 stage F-D rocket that was designed to break the sound barrier with an audible bang (It worked but it flew so high it was unrecoverable). But now, things are way bigger. Hobbyists are using motors from small military missiles, and reloading them too. I was just blown away by what people are doing when I discovered HPR a few years ago. I just did a quick check of online vendors, now people are looking with disdain at puny F and G class motors, they're up to N and O class and above. And this high power requires a higher build quality too. You're basically building military class missiles.

Now the problem is, this stuff all requires licensing. I think you're going to need a consult from a licensed UK HPR builder. There is a hobbyist organization that could surely find an experienced HPR builder who would jump for joy at a chance to work on LOHAN. Check out the United Kingdom Rocketry Association:

http://www.ukra.org.uk/

Now here's where it gets serious. Or does it? Do you want to do a real rockoon and just skip the glider stuff? Because you could probably just do a regular HPR rocket and get the altitude you want, and descent could just be a regular parachute. These HPR guys are all experts in this stuff, they are good at tracking and recovery too.

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Anonymous Coward

It worked for Neil...

Something I know definitely ignites in a vacuum is Aerozine-50, but the engine looks *very* complicated and probably wouldn't scale very well:

http://www.flickr.com/photos/jurvetson/4886815765/

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Happy

Who? What?...

I got somewhat distracted by the film suggested to me after watching your ballocket thingy.

It was called 'Lindsay Lohan - A Richard Phillips Film".

In fact, i got so distracted, i had to watch it twice. Can a copy of this film be sent up with the payload, then, whoever finds it will understand everything.

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Who? What?

I got offered Lindsay Lohan cries in court - gets 90 days.

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