Feeds

back to article Battle continues over LOHAN's mighty rod

The fierce debate continues down at the Low Orbit Helium Assisted Navigator (LOHAN) mosh pit as to whether our proposed launch system for the Vulture 2 spaceplane will actually work. Click here for a bigger version of the LOHAN graphic Our beloved reader experts have soundly dissed our cunning plan as a right load of ballockets …

COMMENTS

This topic is closed for new posts.
Silver badge
Boffin

Why not launch LOHAN straight up from the TOP of the balloon? Thusly:

^

| | - Lohan

OOO

OOOO - Balloon

OOO

|

| - cable

|

===== - avioncs

The teathered avionics should provide enough counterweight to ensure LOHAN is pointed and launched upwards. No worries about twisting effects or icing (or weight!) from the truss/rod arrangement.

Obviously some sort of net would be needed around the balloon to support the launch platform on the vastly expanding balloon. Easily tested on the ground, I'd've thought.

0
0
Silver badge

Let's try that ASCII art again:

Why not launch LOHAN straight up from the TOP of the balloon? Thusly:

.....^.....

....| |.... - Lohan

.OOO.

OOOO - Balloon

.OOO.

.....|.....

.....|..... - cable

.....|.....

===== - avioncs

0
0

In order to work at all, the stabilization moment from the avionics package would have to be transmitted, around a huge balloon, to the launch pad. Otherwise the system will be statically unstable. Creating a rigid frame would dwarf the mass of the plane and the launcher, probably stop the balloon from getting aloft at all.

0
0
Silver badge

Why could the balloon itself not transmit the stabilization moment? (Assuming the avionics package was tethered from a fixed point at the base of the balloon and the launch platform similar at a fixed point at the top of the balloon. (Or from similarly fixed points on a net surrounding the balloon.))

Or do you mean by "statically unstable" that "it would wobble a bit"? Surely less so than the currently proposed truss arrangement that will be swinging in the wind and blasted in every direction by the rocket launch.

So long as the tethered avionic package is significantly heavier than the rocket then LOHAN should be pointing mostly up all of the time. That's more than the truss can ever offer, plus there'll be no need to avoid the balloon at launch.

0
0
Bronze badge

Because the balloon is made out of soft flexible latex. It can't transmit much force to begin with. The problem with mounting the stuff on top is that the balloon swells as it ascends. Any mounting hardware/frame needs to be able to accommodate this, but this would be at best highly impractical.

0
0
Silver badge

> The problem with mounting the stuff on top is that the balloon swells as it ascends.

That's why I suggested using a net. The net would be (ideally) circular and able to contain (say) the top 25% of the balloon at full size. You'd fix the launch platform to the net, put the balloon under the net, and hang the payload from a number of points around the net, using kite string of sufficient length to accommodate to the expansion of the balloon.

So, at launch, something like this:

.....^.....

....| |.... - rocket

..===.. - launch platform

.####.

##### - balloon in net

#####

|....|....|

|....|....|

|....|....|

|....|....|

\....|..../

.|...|...|.

.|...|...|.

.|...|...|.

.|...|...|. - strings from net to avionics

..\..|../..

..|..|..|..

..|..|..|..

..|..|..|..

..|..|..|..

..|..|..|..

...\.|./...

...|.|.|...

...|.|.|...

...|.|.|...

...|.|.|...

....\|/....

.....|.....

===== - avionics

And at high altitude, something like this:

.........................................^.........................................

........................................| | ......- rocket ...................

......................................===.....- launch platform...

.......................###############..........................

...............######################...-net .......

............/OOOO|OOOOO|OOOO|OOOO\................

...........|OOOO|OOOOO|OOOO|OOOOO| - strings

...........|OOOO|OOOOO|OOOO|OOOOO|... enclosing

...........|OOOO|OOOOO|OOOO|OOOOO|.... balloon

............\OOOO|OOOOO|OOOO|OOOO/................

..............\OOO|OOOOO|OOOO|OOOO/.................

................\OOO\OOOO|OOOO/OOOO/..................

...................\...OO\OOO|OOO/OOO.../.....................

......................\.........\....O|O..../........../........................

..........................\.......\.....|...../......../............................

...............................\ ....\..|.../..../..................................

....................................\.\.|././.......................................

.......................................\|/..........................................

........................................|...........................................

...................................===== - avionics .................

0
0

C Rail - Apex Down

I concur with Ron B's description in the article of a truss configuration using an aluminum C rail, with the apex of the truss down and the flat side up. I have previously described the advantages of the apex down/flat up truss.

If the apex is up, that gives two attachment points to the balloon. This allows the truss to roll around the axis of the top rail. If the flat side is up, you could have four attachment points at the corners, giving additional stability along the longitudinal axis of the truss. It would prevent the truss from rolling.

0
0
(Written by Reg staff) Bronze badge

Re: C Rail - Apex Down

"Along the longitudinal axis of the truss" - I think you mean lateral axis.

However, your point is well taken about four attachment points.

0
0
Bronze badge
Boffin

Re: C Rail - Apex Down

"While we're at it, we can try out this suggestion from Ron B:

Hang a drogue (sea anchor style or just a paper streamer) off of the bottom end of the beam so that it always points into the wind"

How many times do we need to repeat this - a free-flying balloon will never be significantly affected by aerodynamic surfaces, as the entire assembly moves with the wind, meaning that the average airspeed is always zero. In fact, this means that _when_ you are unlucky with shear, then the wind over the truss _will_ actually blow in the opposite direction to what you want.

0
0
(Written by Reg staff) Bronze badge

Re: Re: C Rail - Apex Down

The average airspeed is indeed zero. Regarding testing, the problem with a tethered truss is that can't move freely with the breeze, and is therefore artificially subject to wind pressure.

See our fantastical flying truss video, which demonstrates how, if you've got a tether, the truss is pulled down towards the ground by any wind, while it floats gracefully once released.

We often get asked about the PARIS balloon, Vulture 1 and payload passing through the jet stream, as if they subject to extreme winds as you would be if you were a house in a hurricane.

Our PARIS experience showed that the biggest potential problem is long payloads spinning closer to the ground, although a swivel fitting ensures the lines can't get tangled.

0
0
Facepalm

Re: Wind and Spin

Stop repeating yourself and go look at the launch of Vulture or a half dozen other balloons with a camera in the payload. The images are dizzying. If a few ounces of paper streamer will stop that, then I say, "Why not?" It certainly can't hurt.

0
1
(Written by Reg staff) Bronze badge

Re: Re: Wind and Spin

OK, let's put a lid on this debate pending some tests.

1
0
Bronze badge
Coat

Re: Wind and Spin

You ALL have missed the obvious here folks. A simple Sky Hook is all that is needed to secure LOHAN for launch.

Can't really believe all of you supposed "experts" haven't realised this from the start. What a bunch of losers.

Mine's the one hanging on the Unicorn Horn...thanks.

0
0
Silver badge
Holmes

Nike

Just do it! All the pontificating on something that has never been done before is gay. The cost of a failure is certainly less than the Reg staff time spent guessing. Launch it and see what happens.

Also MORE BOOSTERS. Just cause its cooler that way.

1
3
Anonymous Coward

Assisted launch

Stick a spring on the rod, compress it with a cord that burns when the rocket fires.

0
0
Thumb Up

Phase II

Wow. Thanks for the mention in the article. Here's something I thought of after I hit Submit the last time.

The launch has two phases. In the balloon ascent phase you are mostly worried about spin and wind buffeting the conjoined craft. In the launch phase I gather that you want the rocket plane to point up to gain additional altitude. That's smart, because you won't get any lift from those small wings until the craft is back down to ~10km. Anyway, there's a pretty lightweight solution to this: Mount an R/C servo in the beam.

If you shorten the back lines so the beam is almost horizontal, then the wings and body present less surface area to the wind. You would even get some lift from the wings if you put a streamer tail on the beam to point everything into the wind. Once you get above the jet stream, then unwind the rear lines to lower the beam into launch position for the rocket plane.

This can be accomplished many ways. Most of them are fairly simple and foolproof. A straight timer solution would only take a few 556 chips. One to generate the PWM signals (10/90 for ascent, 90/10 for launch) to the servo. Another to trigger the first one into switchover after ~45 minutes.

Servos are also easy to modify for continuous winding if you need more than 270 degrees of rotation to get into position. Then just tie a bead to the end of the line and have it drop off the pulley so it doesn't wind back up.

Also, my aviation experience is limited, but, as far as it goes, ice buildup is a problem when flying through thunderheads (rain or snow clouds). If you are launching on a clear day, then any ice would sublimate as fast as it lands. Private planes fly all day long in clear skies without wing heaters.

Cheers,

Ron

1
0

How about getting 2 aircraft built instead of one. Setup the entire launch gizmo/whatsits in a suspended configuration like it would be at altitude and do some test launches. This would confirm or completely destroy your theories for launch atitude.

0
0
Anonymous Coward

Ice

What about using ultra sonics to vapourise any water/ice before ignition?

0
0
Alien

The golden age of ballooning

The cameras on this one seem to show some quite large swinging movements just before the balloon bursts.

http://www.youtube.com/watch?v=T5VicNzqsQA

0
0
Pint

Launch rails . . . again

Accepting that the drawing 'Vulture 2 Launch system' is a concept drawing rather than a production engineering drawing, the placing of the teflon strips relative to the wings suggests that you anticipate a considerable amount of swinging on the climb. This would be inhibited to a very considerable degree by using the 'U' or 'V' shaped brackets against the wing trailing edges.

I know I am out-voted - I'm not building this miracle of rare device - but I must go with Ron B on the subject of the launch rail. It is a much sounder method of construction, and your concern seems to be that the swing would snap the guide buttons off. If trailing edge brackets can virtually eliminate motion around the roll axis, then surely a launch rail fixed at several points along its length is a more stable solution than a rod mounted at only one end.

Never mind - a glass of beer so I can drink to your success !

Chris Cosgrove

0
0
(Written by Reg staff) Bronze badge

Re: Launch rails . . . again

I'm coming round to the idea of U-brackets against the wing trailing edges. We're consulting with the Southampton lads about this.

0
0
Bronze badge

Re: Launch rails . . . again

Not the best idea really. The trailing edges are rather fragile. Get some longer supports and support LOHAN further "up" the wing and distribute the load over the skin. That would be a better solution imho.

0
0
Anonymous Coward

Magnets.

Use my idea of a salvaged HDD neodymium magnet and iron plate.

Heat magnet to lower Curie point and it will release the iron plate.

Upon confirming release by measuring the magnetic field dropping, send the payload on its merry way.

These typically demagnetise at about 170C as I found out the hard way.

Best way to power the heater resistor is with a single AA Li Energizer which will work fine down to -15C and below with some loss of current.

Even if the cell has lost 75% of its discharge current there should be more than enough to cook that poor magnet into submission.

Simplez!

AC/DC

0
0
This topic is closed for new posts.