back to article LOHAN slips into tight rubber outfit

Last week, the Low Orbit Helium Assisted Navigator (LOHAN) team welcomed rocketeer Paul Shackleton aboard our audacious spaceplane mission. Click here for a bigger version of the LOHAN graphic Accordingly, it's an opportune moment to report on progress on the Vulture 2 motor heater, which will hopefully prevent the aircraft's …

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  1. Annihilator Silver badge
    Headmaster

    "Last week, the Low Orbit Helium* Assisted Navigator (LOHAN) team"

    *Hydrogen. Tra la la la-laa....

  2. Wize

    A low friction connector?

    Spring loaded pins pressing against metal pads, as per a walkie talkie charger. The connection is made while the payload is still locked in place by whatever you are holding it with during the accent.

    1. JonP

      Re: A low friction connector?

      .. or some (weak-ish) magnetic connectors, so you don't have to rely on springs / external forces to hold them in place.

      1. TeeCee Gold badge

        Re: A low friction connector?

        Yup, magnets.

        A couple of steel contact patches on Lohan's skin and a pair of wires from the external power pack ending in small magnets should do the trick. The slight drag on detachment should not be an issue if you ensure that the wires are short enough that this will occur while the spaceplane's still travelling along the launch rod so the trajectory cannot be affected.

    2. Phil O'Sophical Silver badge

      Re: A low friction connector?

      Or braided brushes, a la Scalextric cars/track?

      Or don't use wires, use foil strip and pass that behind the exhaust. It should melt rapidly. In fact, foil with a small notch cut each side should just tear apart as LOHAN's powerful drive thrusts its slim body along the supporting member to penetrate the unknown void...

      Sorry, getting carried away there, as you were.

    3. SW10
      Thumb Up

      Re: A low friction connector?

      A male and female connector is traditional for quick-release coupling. Lube may increase satisfaction and a rubber barrier is recommended...

      1. perlcat
        Coat

        @SW10

        I prefer a viton barrier, due to the higher level of heat generated. Rubber tends to break down.

        1. Martin Budden Bronze badge
          Paris Hilton

          Re: @SW10

          perlcat, you completely missed what SW10 was alluding to, didn't you? I'll give you a clue: the person depicted in the icon to the left of this post is famous for the activity in question.

        2. Phil O'Sophical Silver badge
          Coat

          Re: @SW10

          > higher level of heat generated

          "Do you smoke after sex?"

          "I don't know, I've never looked"

  3. Blitheringeejit
    Headmaster

    You CAN change the laws of physics, Captain - apparently...

    >> less atmosphere to allow heat to radiate away

    Citation needed?

    1. Anonymous Coward
      Anonymous Coward

      Re: You CAN change the laws of physics, Captain - apparently...

      "less atmosphere to allow heat to conduct away" Maybe.

      1. Lester Haines (Written by Reg staff) Gold badge

        Re: Re: You CAN change the laws of physics, Captain - apparently...

        Fair enough, point taken, and so forth

        1. Anonymous Coward
          Anonymous Coward

          Re: Re; Re: You CAN change the laws of physics, Captain - apparently...

          Er... *convect* away, surely?

          1. Anonymous Coward
            Anonymous Coward

            Re: Re; You CAN change the laws of physics, Captain - apparently...

            like centrifugal force, convection is a myth.

            Heat is conducted to the gaseous atmosphere, where so called 'convection currents' move the air around, in reality it's just density, gravity and momentum doing it all.

  4. Drew 11

    Ceramic blanket, anyone?

  5. paulc

    Bubble Wrap & Space Blanket...

    to wrap around the body to keep the heat in...

    or if you want to go high tech low mass insulation, use aerogel...

    1. Lester Haines (Written by Reg staff) Gold badge

      Re: Bubble Wrap & Space Blanket...

      We haven't really got room for external insulation, that's the problem.

      1. Martin Budden Bronze badge

        Re: Bubble Wrap & Space Blanket...

        Have you got room for, say, four layers of space blanket?

  6. Jon Green
    Facepalm

    Polystyrene? Bubble wrap? Aerogel?

    Someone hasn't thought about atmospheric pressure at altitude! Bubble wrap will pop, aerogel will deconstruct, and polystyrene will be useless, as its cells will rupture, evacuate the trapped air, and won't be a whole lot of use as an insulator!

    1. paulc

      Re: Polystyrene? Bubble wrap? Aerogel?

      popped bubble wrap and ruptured polystyrene STILL has structure that hold things apart and the air that has gone is replaced by vacuum... a far better insulator with the only mode of heat transfer from one side to the other being conduction through the plastic and radiation across the vacuum... bubble wrap and expanded polystyrene have the additional mode of convection inside the cells...

      all in all, popped bubble-wrap and ruptured expanded polystyrene will still have a very good insulation figure...

      I'm not sure aerogel will deconstruct as it is an open celled structure in the first place so the air will be replaced by vacuum...

      in fact, aerogel was exposed to open space in the Stardust spacecraft as a trap for particles from comet Wild 2

      http://en.wikipedia.org/wiki/Stardust_%28spacecraft%29#Sample_collection

  7. VeganVegan
    Happy

    A hangar for LOHAN?

    Perhaps it's time to rethink the whole setup, what with all these appuratances anticipated to be wrapping around her, hanging off of her, sticking up her rear end, and such, potentially hindering her free deployment.

    How about an insulated box / hangar, where she can be protected and warm, with some cunning exit portal that she can easily pass through on her way out. Maybe one of those millions-of-bristls type.

    of course, the hangar must have a name: The commentards can be find a good backcronym for JAIL. Oh, and the portal might be called COURT?

  8. Michael H.F. Wilkinson Silver badge
    Joke

    I am surprised

    nobody has suggested duck tape yet

    1. TeeCee Gold badge
      Coat

      Re: I am surprised

      Actually, as we're talking about making an electrical connection, wire coat-hangers would be more appropriate there.

  9. hugo tyson
    Thumb Up

    Double space blanket?

    Have you space for multiple layers of space blanket and heatshrink?

    Can you crumple up the space blanket(s) so it's more likely to have small airspaces too? Assuming the heatshrink is strong enough to contain the overpressure air if it's completely trapped - it certainly looks strong enough...

  10. All Over

    Variation

    How about passing the wires behind the motor where the ends are joined using wax to hold them together that 'instantly' melts/burns away to separate the two ends. Obviously the thickness would need to be rated to avoid resistive heating within the wire avoiding premature separation.

  11. Eugene Crosser

    How much help does the heater provide? Is it worth at all?

    If could be useful to make measurements with the heater disconnected from the battery, for comparison.

    If all you can get is 5℃, it may be not worth the effort. -60℃ vs. -55℃ - not likely to make any difference.

  12. M Gale

    Nice beefy DC-DC converter

    Or some other variety of voltage-stepping jiggery pokery to allow more current to penetrate the resistance of the circuit and get that heater up to more of a toasty temperature. Maybe just two battery packs in series if you want to KISS.

    If you're using a thermocouple and an onboard computer anyway, you could possibly make a slightly more intelligent thermostat than just "on, off". Call one of the computer's analogue IO pins "heater out", feed it into a couple of MOSFETS (maybe via a cheapo signal transistor), and you're laughing.

  13. David Pollard

    Use a transformer?

    It would only require a few components to make something like an isolating power supply, running at 40 kHz or so, with each of the two transformer coils in separate halves of a ferrite-cored transformer. The two halves could be held together by Vulture 2's weight if they were to be mounted on the rubber pad at the end of the titanium rod.

  14. Colin Miller

    Heat loss from inside the tube?

    Did you cap the ends of the tube, or were they left open, thus allowing (air in) the inside of the tube to conduct heat away?

    1. Lester Haines (Written by Reg staff) Gold badge

      Re: Heat loss from inside the tube?

      Good question. I plugged them with cotton wool, otherwise the loss would have been excessive, I reckon.

  15. Greasemonkey
    Boffin

    Radiation & Convection

    Lets get your understanding of heat radiation up to speed:

    Heat radiation takes place even in a vacuum (obviously, otherwise we couldn't see/feel the Sun).

    Heat **convection** is what drops as the ambient density goes down, because the currents of air wafting past your heat source can carry away less heat because of their lower density. I remember 1 of my lecturers commenting that heat loss is dominated by radiation for a small temperature difference like 4 deg. C. Hence the results of your REHAB experiment are what I would have expected: Now, if you had put a more powerful heater in your hyperbaric chamber (bigger delta-T) maybe the result would have been different...

  16. Anonymous Coward
    IT Angle

    Meanwhile, back in LA

    Just as an FYI, the project's namesake escaped prison with an enforced home-based 90 day rehab. However, later that same evening Lindsay was photographed with friends by paparazzi outside a Los Angeles nightclub. When she realized she had been spotted in the back of her friends car, Ms. Lohan ducked down in the back seat and threw a blanket over herself.

    Just thought you should know!!

    1. Lester Haines (Written by Reg staff) Gold badge

      Re: Meanwhile, back in LA

      Yes, our Lindsay is certainly flying the flag for the REHAB bit of the project at least. Good stuff.

    2. Drew 11

      Re: Meanwhile, back in LA

      Was it a ceramic blanket?

      http://en.wikipedia.org/wiki/High_temperature_insulation_wool

      Thin layer of that, held in place with your pilfered heat shrink tubing.

  17. Johnny Canuck

    When might we expect a test launch to verify the launch angle and behavior immediately after launch?

    1. Lester Haines (Written by Reg staff) Gold badge

      Well, the problem here is that a ground-based launch won't have much in common with a launch at high altitude, due to the lack of atmosphere for the control surfaces to "bite" into. We're mulling...

      1. M Gale

        How feasible to make a low-pressure wind tunnel for testing this? Doesn't need to be quite on the scale of the full hypobaric chamber.

        Something like a tube of metal with a glass or polycarbonate window in it, in a circuit with a fan somewhere in it? Have a bulge in the viewing section large enough to put LOHAN. I hear RVK do some pretty neat inline ventilation fans with a quite formidable throughput. The 5" one I've played with creates a veritable hurricane at normal atmospheric pressures. Failing that, see if any model flyers have ducted fans you can borrow?

        Add a variac (or if you're cheap, a dimmer switch) for adjustability in the case of the RVK. Standard speed controller if it's the model aeroplane ducted fan. Use stress sensors on the model mounts to see if there's any lift/control when the surfaces are moved? Perhaps use a smaller section made to be shaped like a part of LOHAN, if you can't fit it all in the tube at once.

        But mostly, use a variac for the steampunk factor.

  18. Gary Bickford

    Another disconnection method

    fuse wire, in the path of the exhaust (perhaps even a length of solder?). I like the foil idea as well, and the spring-pressure knobs could work.

  19. Anonymous Coward
    Anonymous Coward

    disconnection method

    Wrap the wires in Thermate-TH3 or another incendiary, kind of like using thermite but a much lower ignition temperature. Rig up a fuse that can be triggered electrically shortly before your rocket release. You don't want to rely on the rocket plume to trigger the break in the wires, because it might not hang around long enough to provide heat to do the job - and you'll end up with wires still connected. Triggering electronically gives you far more control on timing, and a good incendiary means you can have decent sized insulated wires that aren't going to break easily, but still cut through them in short order when you need to.

    1. The First Dave
      Boffin

      Re: disconnection method

      No need to muck about with anything incendiary - just use a short length of fuse-wire in the right place, and a circuit that is capable of providing the required overload. Even if your burn-out circuit fails to fire, fuse-wire is so soft that it should break anyway once the rocket motor fires.

  20. This post has been deleted by its author

  21. BlueShiftNZ
    Paris Hilton

    Aluminium pole?

    Apart from the relative flimsiness of aluminium for a stripper pole, you're going to get some nasty grey smudges all up their thighs. Chromed stainless steel would be the preferred medium.

    1. Poor Coco
      Thumb Up

      Re: Aluminium pole?

      Good point! It should be kept for the Vulture Festivus celebration and airing of grievances.

  22. Pet Peeve
    Boffin

    Quick disconnect

    A neat little trick is to solder a flat metal tab onto the ends of two pieces of wire, and then hold together the tabs by sandwiching them between two rare-earth magnets, the size of the magnets determining the force to pull the tabs apart. K&J Magnetics is a great place for magnet shopping.

    If you are worried about shorting against something, paint the tabs with liquid electrical tape to insulate them.

  23. Pet Peeve

    oops

    I mean paint on ONE side of each, obviuously!

  24. Mr Young
    Thumb Up

    Just use fuse wire?

    Really thin stuff will survive the job with some proper stress relief and wont make much difference when Vulture 2 is launching up and off her mighty greased pole!

    In memory of Playmonaut:(

  25. Forty Two

    Likely too late in the design cycle but as I cannot find details of the Vulture 2 design I am left wondering if the cavity for the rocket motor could be enlarged slightly in diameter to accommodate a cylinder of insulation material and perhaps a mm or two in additional depth for an insulation hat for the non-functional end of the motor.

  26. Your Opinion Matters

    What about the mag connectors off an old wrecked macbook...

    Handles the current, comes off with an entirely predictable and repeatable force rather than breaking wires etc

  27. Martin Budden Bronze badge
    Go

    Clothes pegs!!!

    This is a back-yard shed project, right? Hold the stripped ends of two wires together with a clothes peg: enough squeeze to hold the wires in contact with each other, loose enough that the wires will pull out easily when LOHAN launches, and exactly the right amount of shed-bodge-ness.

    1. Cliff

      Re: Clothes pegs!!!

      This is in the PARIS spirit! LOHAN is in danger of getting too far away from the shed-fettling that made it so fun!

  28. EvanPyle
    Coat

    power connector

    The easiest ways I can think of for an easy break power connector are:

    1. A slip ring on the pole and a small spring contact (think electric racing car) in the outer tube, allows for rotation an some movement with almost zero breaking force.

    2. Ball up some wire in your typical wall wort connector, sits pretty securely until you pull on it.

    3. Small audio connector, 2.5mm. A well used one comes apart very easy.

    4. Paint connections. Attach thin wires to the body of the rocket with electrically conductive paint, the same stuff you use to repair windows demisters.

  29. Anonymous Coward
    Anonymous Coward

    A space blanket wont help.

    A space blanket wont help when pressed against the engine. Space blankets work by reflecting thermal emission not by insulating them. The silvery surface both reflects more and emits less energy then say a matte black surface would. While the material of a space blanket its self is probably a good conductor of heat. As suggested by "paulc" you want to use an aerogel or foam of some type to insulate it all.

    1. TeeCee Gold badge
      Meh

      Re: A space blanket wont help.

      "Space blankets work by reflecting thermal emission..."

      You mean like reflecting the thermal emissions of the heater layer back in toward the motor where they're wanted rather than letting them warm up the shrinkwrap? That may be why it produces the improvement seen in testing.

      1. kryptonaut

        Re: A space blanket wont help.

        I think that in the test, the space blanket might have reduced the heat transfer to the heatshrink somewhat due to trapped air pockets. But I think it would be far better deployed on the outside (ideally with as little contact as possible between the heatshrink and the space blanket) so that the silvery non-radiative surface is presented to the sky, rather than the efficient black radiator made of heatshrink.

        If you still want the sandwich, at least put another layer of space blanket on the outside so that the external surface won't radiate so much. At altitude, radiation will be the main factor causing cooling.

  30. Anonymous Coward
    Alert

    Am I the only one...

    ... to think that you should also consider vacuum sealing the components together. Then you would have "LiPo Suction" for LOHAN.

  31. Alan Esworthy
    Paris Hilton

    Maximum sensitivity

    With thanks and apologies to Brian Wragg, might I suggest a substitution for the shrink-wrap, one that might also be useful for your quick power disconnection requirement? If the 57 mm Al tube is close to the size of your heater-and-space-blanket-wrapped rocket motor, then a condom could be unrolled over the assembly to hold it all together. Folding the bottom back over itself and then down again would give you a rubber insulated elasticized pocket to hold loosely twisted power supply wires for the heater. Especially with a lubricated condom, the wires should pull apart readily when the time, erm, comes. This admittedly possibly poppycock [1] idea would certainly be consistent with the spirit of this noble endeavor: clever, effective, cheap, and (when possible) lewd.

    1. The word "poppycock" is all the justification I need for the Paris icon.

  32. cortland

    Test setup

    If the objective is to keep the motor warm, the thermocouple should have been somewhere inside the alumin(i)um tube, perhaps in something simulating propellant (modeling clay?) .

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