Original URL: http://www.theregister.co.uk/2011/08/09/lohan_launch_concepts/

LOHAN team buried under ballockets

Click here for a shedload of Reg reader spaceplane launch concepts

By Lester Haines

Posted in SPB, 9th August 2011 11:07 GMT

We sort of knew we'd rue the day we asked you lot for your suggestions as to how exactly to launch our Low Orbit Helium Assisted Navigator (LOHAN) spaceplane, and so it turned out to be, as were were buried under a veritable bucketload of ballockets.

Click here for a bigger version of the LOHAN graphicWhat we're looking for here is a practical way of getting the rocket-powered Vulture 2 off the launch pad at the highest altitude possible, without the whole thing going completely titsup, and in the process destroying both the aircraft and the helium balloon.

You can find our initial concept, and our observations on possible problems, right here.

And now here are your ideas. You're advised to stick the kettle on and dust off a substantial mug, because your going to need plenty of tea to work your way through this lot.

First up, we did say we'd rework your sketches, but then we decided we just didn't have time if we were going to present as many as possible. We also considered it pretty well obligatory to kick off with Dan Lakey's "highly detailed sketch" of the Vulture 2.

Vulture 2 aircraft with tail feathers

Dan explains: "Essentially, sticking some feathers shuttle-cock style on the rocket 1st stage will pull the centre of aerodynamic pressure to the back of the craft. This will make it point skywards, pivoting about the centre of mass.

"So, simply, fire it horizontally and let physics take care of the rest. Drop the 1st stage with the feathers once it's burned out, and the plane reverts to glider-mode. Maybe add a 2nd stage for some fun, because you never can have enough explosives."

Hmmmm. A few of our beloved commenters have already pitched the idea of thrust vectoring, which would allow a horizontal aircraft launch and subsequent majestic arc to the vertical. Dave Gurr also decided to tackle the balloon clearance problem from the Vulture 2 angle.

He says: "Couldn't you have some kind of detachable 'launch wing' attached? You'd have the whole vehicle hanging under the balloon, simply pointing down. The surfaces of the launch wing would be designed to give the whole vehicle and inverted parabolic trajectory ... so that it falls first and then points upwards. At which point some sort of attitude-sensitive microswitch would trigger the rocket and jettison the launch wing."

Vulture 2 with detachable launch wing

Interesting, but it could prove technically tricky. Less is more, we believe, and Calvin Partridge suggests "skipping the complicated stuff and going for a top launch…"

Vulture 1 launch platform on top of balloon

Nick Jones agrees, and here's his cunning plan:

Another top-mounted Vulture 2 launch plan

Sticking the spaceplane above the balloon/s proved very popular, and here's an alternative solution courtesy of Ian Parker. (It's a quick tip of the hat to Thomas Boys and Michael Fenn as well, for sketching the same idea)

Ian says: "This layout would nearly eliminate the risk of the launch hitting the balloon, and the recovery parachute could be used as part of the counterbalance at the bottom of the apparatus (and hey it puts LOHAN on top where she should be)."

A vertical Vulture 2 on top of a pole between two balloons

Mark Benson preferred the single balloon top launcher configuration, and provided this very impressive graphic:

Balloon enclosed in carbon fibre rings with Vulture 2 mounted in top

Mark elaborates: "Carbon fibre rings enclosing the balloon (possibly with a mesh surrounding the balloon to protect against premature bursting) large enough to contain it when fully expanded with the rocket mounted on top and the payload on the bottom. It would allow a clear launch platform and with the potential for wide angle cameras around the circumference of the rings…"

Getting back to the underslung aircraft approach, R Edward Ito favours a curved launch rail idea:

A curved rail launch system for the Vulture 2

He says: "Once you have all the weights down it should be fairly easy to calculate the shape of a curved launch rail that would carry LOHAN aloft in a horizontal position and utilize the centripetal force generated by rocket against the curved rail to swing the rail to a vertical, or nearly so, angle of launch. The rail itself should be fairly simple. The problem will be calculating what is the optimal angle to built into the rail and what the radius of curvature should be. It would also be a good idea to calculate how big the errors can be and still get a good launch."

Shaun Esterhuizen came up with this launch rail alternative...

Another curved launch rail solution

...while James Keir reckoned it's all about the angle of the dangle, as follows: "You dangle LOHAN beneath the payload and balloon on whatever length cord you want. At release altitude, you release the glider/rocket and its mini-counterweight, which is strung to hold the glider at the right angle. Wait for a short time so before firing the rocket and releasing the mini-counterweight. As it drops before the rocket fires, the angle of the wings should steer it clear(ish) of the balloon and payload. It should stay at more or less level bank because the drag on the wings would be equal."

The Vulture 2 attached to the balloon by a string

Barry brewed up a somewhat more complicated version of the same idea, and admits that while it's "a bit more convoluted than using a launch boom", it "should be possible to get an (almost) vertical launch".

He adds: "I thought a low power rocket motor would allow the space plane to get more clearance, but a slingshot would also work." (click on the pic for a bigger version...)

A radical rocket-fired cable release system

Surprisingly, Will Jones was the only person who included a gyro in his design. He lays out his stall thus: "As a way of reducing total weight – and increasing stability – how about using a gyro to stabilise the launch position? Initial idea is to use the deployment rotation of LOHAN to drive a mechanical gear which would spin up a gyro. I have not done any calculations to decide if this would work.. is there enough potential energy in Lohan to get the gyro up to speed enough to hold it in position for a launch?"

Vulture 2 lowered into launch position by gyro control

Will concludes: "However, you could also use a solar panel which would mean the gyro is running all the time (would help with stability during the ascent too). Another option is to spin up the gyro at ground level. Depending on how long the ascent takes.. it will still have enough inertia to hold the launch arm steady."

Menno Treffers couldn't be bothered with gyros. He wants more rockets: "If you attach a rocket the payload and fire horizontally, the payload will rotate upwards to the side of the balloon. That creates room to launch LOHAN."

Vulture 2 propelled into a vertical launch position by a main payload rocket

Dave Prendergast sent in no less than three ideas, all featuring rigid launch booms:

Dave Prendergast's three launch concepts

Here's the full explanation: "Option 1. Shows your launch boom but folded for balloon mode flight. It would deploy to horizontal mode for launch and latch to the rigid vertical boom. The payload box would be located on the vertical in the best location to minimise the pendulum effect. This design would achieve the greatest lift rate and minimise the 'sail effect' that the counterweight and rocket would create on the way up with wind forces acting on them. Once at deployment altitude, wind will be less of an issue.

"Option 2. Shows the launch boom folded for balloon mode flight but the four booms are joined by parachute material of a sufficient area to allow the safe descent of the payload after balloon burst. The length of parachute material between the booms will determine the angle of rocket deployment. This 'umbrella' arrangement will replace the weight of the parachute for safe return of the payload. The drag will slow the ascent and stabilise the launch platform, potentially reducing the amount of counterweight required.

"Option 3. Shows the asymmetrical launch boom in a vertical position for balloon mode flight. Vulture 2's wings could be deployed in this stable lifting mode once at altitude. At release time, the payload releases from the vertical boom and rotates around the fulcrum/pivot, raising the rocket into launch position. The extra length of the rocket side boom helping to clear the balloon more easily. Rotation is stopped with a simple pin; rocket thrust is offset to a degree by the payload mass. This design saves the weight of the counterweight allowing for higher payload capacity."

We don't think we've had enough big springs yet. Cue Richard Possnett: "The balloon would be hooked up to a spring mechanism which would pull it away from Vulture 2 upon bursting, and also function as a launch trigger at the best possible height. Although it may need quite a large spring, maybe a coil which winds up the cord would work better?"

A compressed spring pulls the burst balloon away from Vulture 2 and ignited rocket motor

David Steadman chipped in with this plan...

A pair of separating boxes provides the launch platform

...while also offering something a bit more off-the-wall:

Vulture 2 attached to a weight which pulls it free from the main payload

Tim Harris got right back to basics, but with some solid thinking:

The Vulture 2 launched from the end of a horizontal platform

He says: "By rigging to the ends of the beam, the beam will be be working in compression, with the mass of the payload and Vulture primarily supported by the rigging. This will enable the use of a much lighter spar.

"I have made the assumption that the payload will be heavier than the vehicle, and have done away with the counterweight. This might save a good chunk of weight and also allows the Vulture to be further out for a given length of spar. The centre of mass always hanging beneath the anchor point. (In the drawing the payload is approx. 3X the weight of the vehicle.)

"Because the rig is asymmetrical, it should kite into the wind the vehicle to leeward. you could add a streamer or small windsock for more stability.

"Once Vulture has launched, the payload should have a fairly gentle swing to the new C.O.M."

DMoz liked the idea of a pivoted launch rig...

A simple pivoted launch pole carries the Vulture 2 away from the balloon

...and here's Rob's variation on the theme:

Another launch pole, attached to the top of the balloon

He explains: "Rather than using a counter weight, it just uses the width of the balloon to get your separation. It has the neat property that it throws away your assumption that the balloon will float upright.

"It does require a top attachment to the balloon. I'm not sure if you can glue an attachment to the latex, but if not, a lightweight net around the balloon would do the job of providing a top attachment point.

"You'd have to experiment a bit with the geometry once you knew the weight of the payload and craft, but by adjusting lengths A, B, C, D and the position of attachment point E, you can achieve pretty much any launch angle with minimal additional weight compared to attaching LOHAN to the payload directly."

Gary Keall, meanwhile, suggests putting the launch platform "on the end of a long piece of (say kite) string to clear the balloon (I'll claim the original suggestion of that in the comments) – I'd say 50 if not 100m if the balloon expands to 10s of m across".

The Vulture 2 launched along a fibreglass pole

He continues: "My launch platform would simply be a long lightweight carbon fibre pole (fishing pole?) – about 3-4m I suggest. This is suspended from each end by a string yoke in an asymmetric 'Y' shape to hold the pole at the required launch angle, as shown. I don't think the launch needs to be that near vertical – the ~30° angle show still has plenty of vertical component, and any more vertical and the initial roll orientation of the aircraft will be less defined. The exact angle of dangle depends on where the centre of gravity of the assembly is – I've drawn it assuming most of the mass is in the aircraft at the bottom end.

"As I've drawn it, I envisaged the aircraft attached to a lightweight launch shuttle which slides up the pole on a pair of ring guides or something similar. The aircraft is released from the shuttle by a lever trigger hitting a trip 'noggin' at the end of the pole. This yanks a piece of string which pulls release pins or something like that."

While Gary's design features swing damping vanes, as you can see, Angus Wood suggested using the wind itself to control the relative positions of balloon and payload. He says: "The basic idea is to take advantage of the high wind conditions to create a situation where one is (almost) guaranteed to be able to know where the balloon is in relation to the launcher."

A drag system keeps the payload behind the balloon and orientates the Vulture 2

He continues: "Given that the balloon will have the highest surface area it will catch the most wind and so will always be 'ahead' of the payload and LOHAN. The next step is to orient the rotation of payload in respect to the balloon. This is done by attaching a rudder-like flap of cloth to some aluminium spars which are in turn rigidly attached to the launcher.

"The net effect should be to always aim the LOHAN launcher in to the wind (which is beneficial) and guaranteeing that it will always be pointed at maximal angle away from the helium balloon."

Taking a quick break from the serious and seriously well thought out, let's offer a nod to Alex Jarvis who admits to "many hours photoshopping" to present this explosive concept to the world:

Vulture 2 launched through exploding balloon

Here's the idea: "The premise of this would be you reach launch altitude and fire the rocket and the helium balloon bursts at the same time / fraction of a second later (using a small explosive charge...). The rocket then shoots up and past where the balloon was... Guess there may be a chance to get tangled with the remains of the balloon, but I have a cunning idea for that too. Fill the balloon with hydrogen so when you pop it there will be no remains left due to the awesome explosion you will get. So no launch booms, counterweights etc are required, mount LOHAN underneath and fire through the balloon wreckage! Foolproof launch plan, nothing could go wrong, what is my prize?"

Since you ask, your prize is exactly the same as that on its way to Ross Hartnell, who provided the pic below. Specifically, it's a warning letter from the Civil Aviation Authority warning the pair of you to stay away from rocket motors or face the consequences...

Vulture 2 launched in a tube inside the balloon

Right, onwards. Pretty much all of the above is based on using a single, bog standard balloon.

But what about the toroidal alternative? Eddie, it's over to you: "I get the impression that the launch boom would need to be very strong to support the weight of the ship, and be perfectly balanced with the counter-weight. However I believe there may be a see-saw action involved with the launch boom and counter-weight, when the ship takes off. My idea saves on the use of the launch boom and counter-weight, saving on weight and provides the opportunity of a vertical launch.

"The basic idea is to make the helium balloon a ring, much like a doughnut, with cables going from four (or three to save weight) ringed attachments. The payload will be centred in the middle of the hole (a very large on) approx 10 – 15 metres below. This will allow the structure to remain stable throughout the process.

"The ship will be launched from this point (through the hole in the ring). This allows the ship to launch vertically missing the balloon minus any see-saw actions or instability, provided the helium ring is large enough with a wide hole to allow the ship through with plenty of wiggle room there should be no problems, a device could be fitted to the ring to allow it to make a controlled decent shortly after launch.

"This method will save the weight of the launch boom and counter-weight, needing only the payload (marked as PL in images), the ship and the weight of the balloon plus cables.

"I feel that this may be a little complicated with finding the materials needed (the balloon mainly) and working out all the volumes and harness methods."

Vulture 2 suspended in the middle of a toroidal balloon

Eddie adds: "An alternative suggestion if a single balloon is preferred is to make the balloon flat and build a launch platform on top, a payload supported below the balloon will help maintain stability."

An alternative toroidal set-up, the the launch platform on top of the balloon

Mark Goldie also likes a bit of torus action, but with counterweights to keep it stable:

Another toroidal balloon, with counterweights to keep it stable

Well, the doughnut balloon plan kind of has legs, if someone out there can find one, but it is of course just a single unit. That simply doesn't satisfy some of you, including David Green.

He says: "One possibility would be to use a vertical stack of smaller diameter balloons to reduce the required length of the launch boom as envisaged in your published sketch."

A stack of smaller balloons supporting LOHAN launch boom

The most popular, three balloon set-up, however, was like this one fired over by Adam Newton:

Vulture 2 in a hoop between three balloons

The modified hoop launch system

DMoz got busy again, with this trio of orbs:

Vulture 2 launched up a tube between three balloons

He elaborates: "Essentially the LOHAN craft would be launched from the top of a pole above the balloons. The payload would be situated at the bottom as normal. This can only really work if there is a possibility of attaching stabilising wires to the top of the balloons as well as the bottom, as I can't imagine any cheap substance that will have the required rigidity and lightness to just act as stand-alone (unless you have your own carbon nanotube fabrication plant?).

"Using a tube instead of a pole (is lighter and) enables things to be run from payload up to the craft if needed, but also I am thinking that the support wires could be run through it and attach through the payload to maybe an inertial reel somewhere or the bottom of the balloons allowing the balloons to expand and keep the tension. There would need to be various stops I assume to try to keep the balance, and if the whole system is canted over in high winds you won't get a vertical launch, but it is a thought."

Jason Holloway is also convinced the three-globe set-up is the way to go, and here's his self-explanatory diagram:

Andrew Sheppard offered the most detailed vision of the LOHAN threesome plan:

A triangular launch enclosure between three balloons

He says: "The diagram, which is drawn to scale, shows a 2-metre wide vehicle and three 6-metre balloons (you work out whether the volume is equivalent to one 10-metre one), separated by three spacing devices and with three suspension elements supporting a launch platform.

"Depending on the configuration of the craft and the dimensions of the spacing device, there is about half a metre clearance from vertical to accommodate wind or wobbly lift-off. The launch platform can contain whatever controls and power is required for the launch vehicle, plus the mechanism to retain and release the craft, but needs no additional counterweight or extended 'booms'."

We should take a moment to salute Tim Parker and Philip Sutcliffe, who sent in similar submissions, before winding to a close with a couple of final ideas.

Try Ian William's radical alternative, which involves three parachutes "in a framework, under which the spaceplane is suspended". Ian clarifies: "If you angle the parachutes correctly, the assembly will drift to one side as it falls. Then you can fire the spaceplane vertically up through the framework."

Vulture 2 launch assembly held under three parachutes

And finally, we give you Marc Gale, a man for whom a mere three balloons and a single rocket motor just isn't sufficient.

Marc's pitch explains: "A tricky area would be using the Vulture 2's elevons as rocket canards, as the movement will work the other way around and whatever guidance you have will need to flip its Y axis around to go from Canard Mode to Elevon Mode.

"Probably need a location beacon on each of the stages too. You might want to look at the feasibility of using long streamers instead of parachutes, depending on how heavy each stage is going to be."

Vertically-arranged clusters of balloons to lift LOHAN

A multiple rocket stage concept

We reckon that's a pretty good effort all round, and thanks to all of you who took the time to submit ideas. Obviously, we simply didn't have the time to present every submission, but reckon the above is a fair representation of the main concepts we now have to mull.

So, what's next? Well, beloved ballocketeers, the answer is that we hit the fab bunker and make scale models of some of the above and see how they fly. Watch this space... ®

Bootnote

A special mention must go to David Swanson, for his radical contribution which didn't really fit into any of the broad categories above:

The radical helium balloon valve design

Here's David's explanation:

Concerning the LOHAN balloon launch system, I've written out an idea which would lift the craft underneath a single balloon and launch it vertically, by allowing a controlled deflation and disposal of the balloon. As a plus, it works without electronics.

I have a diagram drawn which would help explain my thinking, I just don't know where to send it. Overall, Vulture 2 (or possibly a launch platform), would have a hole going through it's center tapering out larger towards the bottom. A deflation mechanism will attach to the balloon, and fit in this hole such that the hole taper will attach the balloon directly to the craft.

System Component Description:

Balloon – Weather balloon, which I am really not familiar with.

Deflation Mechanism – 3-part device that secures a tube inside the neck of the balloon, has a clamp around the outside of the balloon, and a plug on the very bottom of the tube. The plug will require a release mechanism to vent the plug when desired. The mechanism has tapered sides that match up with the hole going through Vulture 2.

Balloon Clearance Bearings – Ball bearings, or some similar device on spring loaded arms. Located on the top of the inner hole. They rest on the deflation mechanism.

Shielding Struts – lightweight struts projecting outwards around LOHAN to provide some protection to the control surfaces.

Theory of Operation:

1. At predetermined height/pressure/time release mechanism will open the plug on the balloon, resulting in a deflating balloon, whose helium will be directed downwards, giving a last bit of acceleration.

2. When acceleration from balloon deflation has stopped, the deflation mechanism will begin to fall out the bottom of the craft, since the taper is only holding it in, pulling the balloon with it.

3. The balloon clearance bearings will spring inwards once the Deflation Mechanism has started to fall. This is to minimise the balloon scraping along the inside. As this point the Deflation Mechanism will be below the craft, but still attached to it by the deflated balloon. If the craft begins to tumble, the latex will contact in the direction that the craft is tipping, and pull it back towards vertical position.

4a. If the balloon successfully clears the craft, through its central hole, Vulture 2 will now be oriented vertically ready to eject the shielding struts and ignite rockets.

4b. If the balloon was to slag off to one side of the craft on top, it should become entangled on the shielding struts. If the deflation mechanism rivals the weight of the balloon, it should still be able to stabilize the craft. In this situation it would be preferable to have the rockets directed through the central hole. The hot exhaust would burn through the balloon, allowing it to fall free off the craft with the shielding struts, giving a free craft launching in a vertical position.