HAPS-1, UMSFB1 redux Options

[djellison]

I'd be interested to see what people would change in terms of pointing, orientation, and image sequencing with just the one camera for future flights - and if they could have a second camera, what they'd do with it.

Doug

[ugordan]

Well, one suggestion that comes to mind when looking at the images would be to have one camera as is or even tilt it downward ever so slightly, while the other pointing near-nadir, say at a 90 deg angle to the first one. The panorama is, after all, missing the central portion.

Since the second cam would be looking almost straight down pretty much all the time, there'd be no need to capture as many images that just end up being rotated. Maybe longer movies instead?

[jamescanvin]

Well this goes back to all those sims I did back in the old UMSFB thread. With one camera I think as is was about perfect. If I got to add a second camera then for sure it needs to point downish. Thinking back to my sims, I would suggest having it in 'portrait' orientation with the lower edge close but not quite nadir (centre of image about -50 degrees elevation (FOV is ~53 degrees, so this would capture ~-24 to -76 degrees elevation in level flight)

Maybe it's time to break out that sim code again now we have more data on how the balloon really behaves.

[JTN]

May I ask about the complications involved to "clear" this flight ?
Is the BAA not "down with this sort of thing"...

I don't know about this specific flight -- maybe Doug or James Coxon can say -- but on the Pegasus wiki for a previous flight there's this description of the permission/notice procedure.

[Juramike]

It seemed that when the limb was thinner (more black sky, soooo cool) the exposure setting function would blow out the horizon.

If there was any way possible with hardware or software to dampen down the exposure changes....

-Mike

[djellison]

If there was any way possible with hardware or software to dampen down the exposure changes....

Without risking under-exposing the other images - no. We could bracket-expose images, but that trebles the data volume and probably wouldn't get the range anyway. It's just one of those things. Take enough shots such that yeah, you'll get loads of over exposed dark images, but you still get enough good ones.

Doug

[Ant103]

Wow
It's an amazing work. Really impress by pictures taken during the ascending of HAPS-1.
Doug and other, you made a GREAT work .

Love the last part of the second edited movie, when the wind dicrease, it's a moment of serenity .

[ElkGroveDan]

Can't think of much else I would do different. All things considered this was a most amazing first-time effort. Darn near perfect when you consider the goals outlined in that earlier balloon discussion.

Perhaps some additional instrumentation would add to the experience next time, like a rudimentary accelerometer. Maybe some kind of radiation or cosmic-ray detecting device.

[Tman]

What wind speed hit still the payload box in the flight with the balloon? It isn't nearly zero, is it?

If you get still enough wind on the box, I would start/search some tests on the compact form of the box in order to get the rotation under better control. Maybe it could be even possible to control a desired speed and direction of the rotation during some time of the flight.
How about a compact rugby-ball-like form, maybe such deformed that you get a desired rotation? In this context it would be also relevant how the payload box is connected to the balloon/parachute cord - fixed or turnable.

[djellison]

What wind speed hit still the payload box in the flight with the balloon?

Anything from 0 kph to more than 100, and it can change very quickly as we rise thru different layers. Sunday there was almost no jet-stream - but sometimes it can be >100kph - and you could go from 0-100 in a mintue or two.

WE go up at about 10-15kph, BUT, anything you put on the payload to use that 15kph to rotate ( like the fins on Huygens) is going to influence the payload via the cross-winds far far more than the wind of ascent.

Doug

[AndyG]

The best way is to make a small payload, and put it on a long long line to the balloon and let the laws of physics ( and the low frequency of the pendulum you're left with) do the rest.

Doug, having just looked through the videos again:

The images are lovely - though I'm trying to work out whether the drop in pitch of the on-board mic with altitude is a function of air pressure or cold or both.

A more stable instrument platform would seem to be the next step. As you say, a longer tether would lower the frequency. It would also help by moving the package out of the worst of the turbulence "behind" what is an unstreamlined object moving at a fast jog (16 kmph) straight up.

Since vanes to supress horizontal rotation can't work (surely the balloon is moving virtually at any surrounding horizontal airspeed?) and would be a disadvantage under pedulum swing (they'd feathervane the package on each swing), why not try increasing the rotational inertia of the package?

If you went for a pair of long booms with a mass at the ends, it'd be more stable - though still free to move, allowing for panoramic views. Better, if you had three booms, you could go for a long tripod-like tether which would hang the package with a virtually assured horizon. Mass increases could be minimal - and you could boom-mount a camera with no negative effects.

Placing the parachute below the balloon but above a bridle for this sort of tether would surely not increase the risk of tangle? (In the video we get a quick shot of near zero g when the package starts falling with balloon material around it, until the parachute fills.)

Incidentally, tell me the parachute falling juicily into frame in the last video is a fix?! Too lucky by half!!!

Andy

[djellison]

tell me the parachute falling juicily into frame in the last video is a fix?!

We didn't arrive for another 2 1/2 hours.

I think people are missing a point here. The payload is stable to the point of images being, on the whole, not blurred ( which is down, mainly, to a single payload 'deck', and a very long balloon-to-payload line ). Beyond that, you don't want a stable payload, because otherwise you would have a thousand images of the same direction. You don't want that. You want it moving around a bit to fill in the panoramas - and to be honest, all the ideas we could possibly come up with add things for lines to get wrapped around at launch, flight, and burst ( bad ) and mass ( very very bad ).

Look at the movies just before the burst. They're astonishingly stable, and have a nice gentle rotation. I think the trick I've missed is not doing enough stills sequentially. I think next time I'll do an imaging minute, then a movie minute ( so 20xstills, then a gap, then a 15s movie, then 45sec, repeat) . What we need is an imaging strategy based on the sort of dynamics we see with this flight - to get better mosaics out of it.

Incidentally, no one has started making mosaics from the movie frames yet... It sort of works, but will take some work.

Doug

[Ant103]

And what about a small camera with wide angle, like a fisheye view, at the bottom of payload, looking at the ground (a sort of MARDI-like instrument) ? It will complete the imagery setting with the first camera.
Tell me if it's a bad idea

[djellison]

That is something I'd like to do, and I think I can for about 50g - getting a fish-eye lens to do it, though, is quite hard. A Vistaquest 1005 would do the job ( google Catcam ) - but a wide angle lens is hard to find that small - infact, I'd like two - one up, and one down

Doug

[jekbradbury]

A lower-mid-altitude (EDIT: ~3000m to ~3200m) horizon pan: