HAPS-1, UMSFB1 redux Options

[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:

[djellison]

Given the fact that you could almost walk from Cambridge to Norwich without being more than 20ft from an RAF base at any time, I was about to say 'Wow - a bit of Norfolk without an RAF base' - but actually, there is one hiding in there. Great work - why on earth would anyone ever hold back with their pictures and not let people do this sort of thing.

[jekbradbury]

What is the reason for the 30 second sleep in every minute of camera operation? Is it heat, space on SD card, or something else?

[Juramike]

The potential for getting regional haze layer information totally fascinates me:

How about using two cameras as suggested (one pointed towards the horizon, one looking sorta downwards) but with polarizing filters over the lenses. The two (relatively cheap) polarizing filters could be offset by 90 degrees.

You'll probably get enough swing that you get overlapping images of the horizon with both cameras. Presto, you get two different polarization modes.

-Mike

[ugordan]

Presto, you get two different polarization modes.

You'd still need calibration capability of the data as two different, cheap-o cameras will behave quite differently even in identical conditions. Remember we're not dealing with scientific instruments here!

[djellison]

space on SD card

Bingo. I wanted a 50% buffer on capacity. From when I turned it on, to landing, used just over half the card. I wasn't 100% sure what the average image size would be at altitude ( taking a photo of a photo from altitude doesn't work as a test ) and there's a HUGE question mark over flight time (2hrs 50 we got - could have been an hour longer, or an hour less without too much being different)

So - I was cautious, but as a result, we got the entire flight fairly well documented instead of most of it very well documented or some of it brilliantly documented

Doug

[ngunn]

This whole thing has been an astonishing and beautiful sucess - enormous congratulations to everyone involved. You may recall I was interested way back in 3D image possibilities from this project. With so many images obtained from many different heights and no doubt some relative movement horizontally too I wonder if anyone has tried cloud 3D (viewed with the horizon vertical-ish?)

[hendric]

Doug,

Does your camera have a UV filter? That might help a bit with being able to see farther through the haze.

If you do have a downwards-viewing camera, may I suggest a wind tell-tale a la Phoenix? It will not mean much scientifically, but would be cool to watch. Maybe a short stick pointing downwards with a shorter section of ribbon? (There's a sponsorship idea, buy an "inch" of ribbon and the team will write your name on it!)

Other than that, it looks perfect to me! Wouldn't it be great if every weather balloon had an imaging package?

[ugordan]

I wonder if anyone has tried cloud 3D (viewed with the horizon vertical-ish?)

I tried, but it's mainly a no-go because of cloud evolution and various lateral motions. This for example doesn't look at all impressive:

It's probably only good for giving one a headache.

[ngunn]

It's probably only good for giving one a headache.

Ha! Very interesting all the same to see that attempt. Those clouds are of course a particularly fast-evolving type of cloud. It might work better with some of the higher ones. Maybe a much higher view looking down through the various layers? Of course it would be easy enough to shoot nice simultaneous pairs of terrestrial clouds from the ground, but I'm thinking of the implications for balloon probes at Titan or Venus. How effectively can evolving cloud forms be studied using images from a single, moving platform within the atmosphere? I think what you've done there does at least begin to address that question. Maybe this is another consideration to factor into the imaging strategy for follow-ups.

[ElkGroveDan]

I tried, but it's mainly a no-go because of cloud evolution and various lateral motions.

Clearly, we need a camera on each end of a twenty foot pole. I guess that will have to wait for the larger payload that will be necessary for the IMAX version.