Posts by Magnus_Pym

LOHAN ideas..

Re: measuring release altitude for launch

The PARIS balloon got up to about 90,000 ft before it burst. Any pre-burst release would have to be considerably less that this to be sure of success.

Re: Two balloon

If the ultimate altitude doesn't matter then why not tie a firework rocket to a toy a balloon and have it go off at 20 feet? It will have achieved a rockoon type thing.

Re: Two balloons revisited...launch control and maximising lauch altitude

As far as I understand it the explosive self destruction of a balloon at altitude could damage anything too close and would certainly cause another balloon next to it to burst. They would need to be some distance apart, probably one above the other. Difficult but not impossible to arrange. This arrangement would induce the platform to bounce rather than swing at the loss of one balloon (or set of balloons) which may or may not be better.

Re: Two balloon

There are problems, How to tether the balloons, what happens after burst and the payload is bouncing like it's on a bungee cord for a some time. However I still have had no answer to the question:

Will the rocket add enough to the total altitude to make up for the margin for error that must be allowed to ensure that a single balloon will definitely not have burst at launch?

Two balloon

Up for discussion is the two balloon scenario as mentioned on the latest LOHAN post.

Two balloons one high above the other both connected to a strain gauge type micro-switch on their tethers. When either one of the balloons burst its micro-switch fires the rocket. A timer is used to only arm the system only after a suitable delay after release to alloy the craft to enter the calmer air in the upper atmosphere.

1. Simple to build

2. Ensures maximum altitude before launch

3. Remaining balloon stabilises platform for launch

4. Fails safe, if one balloon burst early the rocket will still fire at altitude on the timer

5. Can be tested at low altitude

Re: Another mighty initial thrust idea

"Agreed. Some form of ground-based test is indeed required."

Great. Can't wait to see it.

Re: Here's a thought

I know and they don't always work. It may be necessary to break the LOHAN project into two parts.

1. A successfull Rockoon launch

2. A Plarockoon attempt

Re: Another mighty initial thrust idea

To Summarise then:

1. A rod/rail launch may or may not produce a straight line launch from a free swinging platform

2. A rod/rail launch may or may not actually slide due to static friction vs small inertial forces

3. A rocket-plane may or may not require giro-stabalisation due to out of line forces

4. No one really reads the detail and meaning of the other posts.

Conclusion:

I back iamanidiot: The arguing phase is over and proof is required. Either hard maths or testing.

Re: Another mighty initial thrust idea

"the enormous difference that you don’t seem to see"

That's what this bit was about:

"Especially if that launch is from a suspended platform."

Perhaps it would have been clearer to say 'free moving suspended platform'.

My point was that the problems of stabilising the plane/rocket combo (or plocket (tm)) and the non-fixed launched platform WILL show that we are in trouble BEFORE we go adding in low air density and low temperatures to the list of problems.

Re: Another mighty initial thrust idea

I have to say that while I can see that there is lots of evidence of ground based rockets launching successfully (and more than a few unsuccessful ones). The additional problems of an air launch and a rocket-that-must-also-function-as-a-plane make these all but irrelevant to the LOHAN project.

It's my belief that a test launch at ground level will make the differences abundantly clear. Especially if that launch is from a suspended platform.

Re: Another mighty initial thrust idea

LeeE:

"If the mass of the girder+payload is zero, the air resistance is zero and the friction of plane against the rod is any value greater than zero"

My point was not that air resistance is related to mass - but that both are very low so that the total of the forces available to act against friction are also very low. At the point of firing the rocket, before the plane has any speed relative to the rod, it cannot overcome even a small force due to friction so any icing or damage to the mechanisms will result in the plane dragging the launch platform. Also there is very little mass to build inertial forces to prevent the launch platform turning so any out of balance forces will render the rod critically unstable.

I'm not getting much support for my theories and there is a lot of real knowledge on this forum so I am probably wrong.

Re: Another mighty initial thrust idea

Poor Coco: Thanks for answering my query. I still contend that the masses involved are purposefully low and this makes it difficult to create balancing forces. I suppose all that can be tested at ground level so not so much of a gamble.

I suggest that in order to maximise inertia in three dimensions a good design might be to arrange the payload into four equal masses mounted on the end of relatively long rods of equal length and arranged to form a tetrahedron centred on the base of the launch rod. This might also lend itself to some good camera angles.

Re: Another mighty initial thrust idea

My point is that there is nothing holding the rod still or at a fixed direction for the plane to run off it.

If the mass of the girder+payload is zero, the air resistance is zero and the friction of plane against the rod is any value greater than zero then the rod will remain with the plane. In most designs the power is out of line with rod so a turning moment is created. . In real life the values are all small and so small differences are significant. If the friction is higher than the mass can balance then the plane may drag the girder. If the mass is too low the girder may rotate about its centre of gravity. It will fail to constrain or even impede the launch.

The rod (or any other device attached to the girder) is unlikely to add stability to the launch but is likely to cause problems.

Re: Another mighty initial thrust idea

As with any launch method discussed here there is essentially no fixed point. Any forces on the launch mechanism can only be counteracted by the inertia from the mass of the rest of the payload (which is deliberately kept to a minimum) and the balloon itself (little mass, negative weight and little air resistance at altitude). Even it doesn't freeze it will have to be remarkably friction free to prevent the rocket simply pulling the whole girder/balloon combo along with it as there is so little 'pulling the other way'. Without sufficient mass there is nothing to keep a rail pointing in the same direction all the time either.

Without a fixed point to launch from the craft must simply be released and be able to set its own course.

Here's a thought

Maybe it would be better to forget about the glider and just launch a properly controlled and configured rocket from the balloon and let it come down on a parachute. Once that is proved to work you can see how to get a glider into the payload of a rocket.

Vulture 2 trigger triggers serious head-scratching

I agree but there is no need to have two differently filled balloons. They will be very unlikely to burst at exactly the same time. Either can trigger release. Also the payload may remain stable for some time after launch for some better shots.

I notice his GPS based altimeter stopped working at about 24,000 feet. Also the barometric altitude and GPS altitude show cosiderable difference above about 17,000 feet.

LOHAN !> PARIS?

All pressure or altitude based firing systems rely on firing the rocket before the balloon bursts, or to put it another way before maximum altitude is reached. Balloon bursting is unpredictable to say the least and pressure or altitude measurement may not be exact so some large margin for error must be allowed. This margin for error is likely to be larger than the distance the rocket will travel. So in effect LOHAN will be a lot more trouble but may achieve less than PARIS.

No mention of the...

two balloon system?

LOHAN starts to feel the barometric pressure

Re: Two balloons

As far as I am aware you can't attach things to the side of the balloon. It's just a very thing latex skin. However the two balloon system is easily the best. Two identical balloons are unlikely to burst at exactly the same moment and the difference in lift can be used to fire the rocket while the remaining balloon provides stability to the platform.

Re: Post post burst launch

Due to the very little atmosphere a drogue will have very little effect. You would need an enormous canopy and that would be very difficult to deploy. Hence the massive groundswell of support for the two balloon system.

Re: Fire at point of bursting

@Poor_Coco: I suggested launching from a dropping platform on the LOHAN discussion forum. It was soundly beaten down due to the inability to control the direction of launch with the platform in free fall.

@Gordon 10: It is a strain Gauge isn't it? delaying for one second and resetting after each false alarm adds to the complexity of the circuit.

After one balloon burst the payload will loose altitude but only slowly and in a controlled manner. The timer is required to prevent a premature due to buffeting by strong winds in some parts of the atmosphere.

Also it would tend to fail safe because in the event of a balloon bursting early the rocket will be fired immediately on time-out. I think it would be possible to put the switch block in a flexible airtight enclosure (with some silica gel or something) to prevent damp and cold from interfering with the operation.

Re: Fire at point of bursting

I asked about how much altitude the rocket is expected to add to the total flight but no one has come up with an answer yet. It could easily be less that the margin-for-error launch altitude takes away.

I was wondering about using two balloons. The launch is triggered by the loss of one balloon. I can't see a reliable way of measuring this though. I think they can be given a large enough separation to prevent the explosion of one bursting the other by having one on a much longer string than the other. The main problem I see is the turbulent lower altitude phase interfering with any reliable measure.

What about this? Two balloons one high above the other. Each balloon's string is attached to it's own tether on the top of a small switch block. A single string then passes down from the bottom of the switch block to the payload. Each tether is attached to a switch mechanism. A spring pulls the switch towards the 'closed' position and the 'lift' from the balloon acts against it. When either balloon bursts 'lift' is lost and it's switch will be closed. A timer is set to allow enough time for the craft to have passed the turbulent levels of atmosphere before the system is armed. A simple circuit can then fire the rocket if the timer has elapsed and either one of the switches is closed.

Post-pub nosh deathmatch: Mealy pudding v migas

Where the fried bread?

Fried in beef dripping, now there's a healthy addition to any meal.

What is SpaceX Dragon's secret cargo?

Not a sealed tin of Spam.

Not in a low pressure environment anyway. Maybe some trout and a salmon to do the Fish Slapping Dance on a space walk.

Pinterest valued at $1.5 BILLION, bags $100m in funding

Re: app (PMTerest)

Allows users to upload pictures of their loved ones, kittens and nice stuff and then destroy them (in a virtual way) at the appropriate time.

Re: Sod it - I'm starting a social network

more a sort of anti-social media site?

Vixie warns: DNS Changer ‘blackouts’ inevitable

Re: Hey Paul, this is an opportunity

When users get calls like "Hi, I'm Dave calling from Microsoft we have discovered a fault with your Windows computer etc". It is not surprising they distrust cold calls from IT support.

HTC phones held up at US ports after Apple patent ban

I should have patented...

...exploding underpants. a) I could have sued two terrorist organizations by now ($$$$$$) and b) all travelers would have to surrender all their underpants to customs officials to be checked for explodability.

125,000 Ubuntu PCs to land in Pakistani students' laps

Re: Let's ditch the stereotype

Yes. I was wondering who these where aimed at. I thought perhaps more rural areas but if there is internet access there will probably already be computers if there isn't then these won't be much use.

Re: Open source zero cost?

No, Anonymous Coward, I read it and called it as I saw fit and told you my reasoning. Don't like it? Then say why rather than just impugning my character.

Re: Open source zero cost?

I called FUD because you post anonymously and suggest that going F/OSS is going to cost a lot of money by necessity. That is the very definition of spreading fear, uncertainty and doubt.

I agree that there are costs involved but it won't necessarily call for a full fat RH contract.

Re: Open source zero cost?

You are the FUD and I claim my prize.

Re: This could bite them in the arse

It's the old guard mediaeval/feudal/misogynistic attitude that needs to be 'educated' away. That is more of a 'tradition' than a specifically Muslim problem and exists the world over not just in Muslim countries.

Spy under your car bonnet 'worth billions by 2016'

telemetry

A few years a go some guy's Range Rover proved him innocent in a traffic case by the telemetry information on it's computer. I'm sure the 'driverless car' technology could be used to provide a co-driver type thing instead and use the information gathered to tell everybody about the stupid and irresponsible things some drivers do.

If they really knew...

... what some peoples driving was like they wouldn't get insurance. A small percentage of terrible drivers that cause a large percentage of the claims (directly or indirectly). If the insurance companies knew how bad their driving really was they wouldn't get insurance. Accidents would go down, Insurance would be cheaper. However there would be far more uninsured drivers less people to cover the costs so insurance would go back up.

Cameron's F-35 U-turn: BAE Systems still calls the shots at No 10

Cloudbase - obviously

What we need is a huge LEMV held constantly in the upper atmosphere. with a runway on the top. No need to 'launch' the planes, just drop them off the end to gain airspeed in the fall. Only needs a trap then and as a bonus the pilot is much further away from the sea when the trap fails.

Facebook co-founder renounces US citizenship pre-IPO

Where did his original $1,000 dollars come from?

If he risked his own hard earned money on a wild card investment like facebook he invested wisely an benefited in proportion to his risk. $1,000 dollars represents a good proportion of the money available to live on. The lack of $1,000 dollars would have impacted on his lifestyle a great deal. With only what a student could earn working part time very few would risk that much money on such a venture.

However if his parents gave it to him along with his 'allowance' then the risk he took is severely diminished and so the enormous rewards are more difficult to justify.

Queen unveils draft internet super-snoop bill - with clauses

Re: No worries

"I'm still rather uneasy that our future liberty relies on the fact that all our governments are completely fucking useless..."

Unsettling yes but true. It is similar to the one man, one dog space ship crew only you don't need the dog.

No worries

It's a government IT project. It'll be years before anything turns up and even then it won't work.

At last! A use for Blighty's phone-boxes: Free Wi-Fi hotspots

Great...

.. if you have one of these phone boxes right outside your house!

Apache releases new OpenOffice build, promises faster upgrades

Re: Yay, everyone loses.

Everyone has already won.

The availability of FOSS has meant that the likes of Microsoft face comparison with good quality, properly coded software. Where they have clearly been taking the piss (ie) they have lost out. Software is cheaper and better now because of FOSS.

Microsoft scrapes Windows Azure name off cloudy kit

Microsoft nomenclature

1. Take the de facto generally used name

2. own it

3. copyright it

4. profit

see: DOS, Windows, SQL server.

Pilots asking not to fly F-22 after oxygen problems

Re: Would the F23 have had the same problems?

"Probably not, it would have had New and Exciting problems :)"

No. It would have had New and Exciting Opportunities

Nokia's 41Mp cameraphone shoots towards retail

Re: FAIL

Symbian? I want it.

Computer nostalgia is 10 PRINT 'BOLLOCKS'

Re: Was i the only one to remember

Is that the one with 'The music is reversible. Turn back, turn back'. recorded in reverse at the end? Try doing that with an iPod

Nympho hauled to loon-cooler after serial bonkathon brutality

nyphomania?

Almost certainly not. May have been erotomania. Could have been a psychotic episode brought on by mental illness. Could have been made up to sell papers.

iTunes fanbois outraged by Apple's sex-life quiz probe

"My first boss was Barry ______."

Shitpeas? easy

Freed Facebook hack Brit vents fury at $200k cleanup claim

Re: lopsided extradition?

That could be because the British requests have to be accompanied by EVIDENCE therefore less likely to be spurious.

Intel bakes palm-sized Core i5 NUC to rival Raspberry Pi

Fan = show stopper

A fan is moving parts and single point of failure. Best avoided if possible especially for embedded systems.