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back to article LOHAN embraces handsome young autopilot

We invite fans of our Low Orbit Helium Assisted Navigator (LOHAN) project to raise a glass or two today to UAV specialist 3D Robotics, which has very kindly agreed to offer our Vulture 2 spaceplane a brain transplant in the form of the mighty Pixhawk autopilot. Two views of the 3D robotics Pixhawk As LOHAN regulars know, our …

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Paris Hilton

So it's the SYLVIE experiment?

Like Servo-controlled, Year-Long Validated, Interesting Experiment or something?

Paris 'cos Sylvie isn't available as an icon.

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Paris Hilton

Internal rejiggery ahead...

looks like you might not have much space to play around with especially as you need to keep your centre of gravity in the same place...

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(Written by Reg staff) Silver badge

Re: Internal rejiggery ahead...

We've got plenty of room, but as you say, a bit of jiggery-pokery is in order to sort the C of G.

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Bronze badge

Thank heavens for boffins

You read story after story of some Big Bad Corp or Corp v Corp sueball tournament and then suddenly as a bolt from the blue there is this bunch of enthusiasts and real world companies willing to put reputations (and money) on the line for pure escapist fanatasy projects.

Gawd bless 'em one and all

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Paris Hilton

The sky's the limit

Wow there is some seriously sophisticated engineering going on here. Not so sure that 'Garden Shed' boffinry still fits the description of this project anymore.

Paris, as in we'll always have Paris (to remember good old fashioned string and paper bodgery).

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(Written by Reg staff) Silver badge

Re: The sky's the limit

Fret ye not, LOHAN still likes a nice bit of shed.

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Silver badge

Re: The sky's the limit

This actually was my concern too. We mustn't lose sight of the blu-tac and selotape.

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Anonymous Coward

Big oops

It's got rounded corners. I think there's aPpatent for that.

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Two stage autopilot

It looks like the autopilot will need 2 stages ~

Stage one, the truss swings and launches in a vertical - ish direction, the autopilot needs to either be nutral or adjust to a vertical trajectory for the duration of the burn plus a little get max altitude before ~

Stage 2, Normal horizontal flight.

Its actually a little more complicated, no doubt someone will comment about control surface throws for high speed thin air flight relative to normal thick air flight, relative to slowing down for a soft landing.

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Silver badge

Re: Two stage autopilot

There might be a need for an intermediate stage, "Plummet". Recently someone else successfully guided a HAB-released glider down into a pre-determined field, they had a deliberate and very gratifying Plummet stage in their flight.

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Pirate

Re: Plummet

I think you may find that Lemmings have the patent on "Plummet". Please cease all use of the word especially in relation to gut wrenching free-fall.

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(Written by Reg staff) Silver badge

Re: Two stage autopilot

The way we're currently looking at it is:

1) Autopilot in "neutral" until after rocket motor burn

2) High-speed dive at high altitude (aka "plummet")

3) Low-speed glide to landing

Part 1) is actually the difficult bit. We need to work out how the autopilot is going to sense launch.

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Bronze badge

Re: Two stage autopilot

Either intertial acceleration or electrically, when the heater disconnects from the battery.

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(Written by Reg staff) Silver badge

Re: Re: Two stage autopilot

Yup, there are various options available.

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Re: Two stage autopilot

Ok, this might sound a bit stupid, but why doesn't the autopilot *initiate* the rocket burn?

This would cut down on the number of electrical connections from the launcher to the plane and make "detection of launch" easier.

If you need to communicate between the launcher box and the plane, for example to initiate launch early, you could do it via infrared (IR-transistor on the recieving end, transistor+resistor+IR diode on the sender; easy as PI).

If you really just want to passively detect the rocket ignition, looking for a sudden, 3 second forward acceleration followed by a rather steep temperature increase of the rocket casing and a rather steep fall in altitude[*] should be a good indication.

[*] If you detect a rather steep fall *followed* by a sudden deceleration it means to waited a bit to long.

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