Internal vs. external in-flight video recorder

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billdz

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I really enjoy in-flight video and had been well satisfied with the video from my $5 keychain camera until I saw it side by side with Jason Cook's video. See https://www.facebook.com/seahawks.pal/posts/2429482710609212.

Now I'm thinking about an upgrade. There are two distinct ways to go: 1) a RunCam, Mobius, or other higher-level mini-DVR that is taped to the outside of the rocket, or 2) a cell phone like Jason's Nexus 5X inside the rocket. The 5X is also an altimeter and provides GPS tracking and flight data and graphs via the Insane Rockets app, but it is heavier and requires a hole in the airframe for the lens. The Mobius is lighter and simpler but it only makes videos, it does not look particularly attractive taped to the airframe, and it may impair the aerodynamics of the rocket Any thoughts on which system is better?

Thanks,
Bill
 
In case you haven't heard of these guys:
https://www.additiveaerospace.com/
https://www.liquidfyre-rocketry.com/

I vacuum formed a shroud for my keyfob camera. Worked okay, the second round was more streamlined. LiquidFyre is internal with an external lens. Only fisheye is available ATM, but that is soon changing as I understand it...with the Mobius Mini and that is on my must have list.
Additive is externally mounted camera pointing down.
I will eventually put me a camera pointed straight out the side just for kicks. Just haven't done it yet.
 
I like the view down the rocket much more than the view to the side. It gives the viewer much more sensation of speed and altitude.

You can get great video from a Mobius in a printed shroud:
[YOUTUBE]ahpt81EWN40[/YOUTUBE]

If you want better quality video you can use a Sony 4k Action Cam. This took a lot more work to design and build the mount:
[YOUTUBE]MCENpKaTClA[/YOUTUBE]
 
Well, my fins must not be as good as I think they are. I tried a camera on a few of my rockets (3 fins) and the video was nausea-inducing. Next for me is 4-fins to see of that makes a difference.

Don't think that makes a difference. I have one with 4 fins and is also nauseating to watch but most of my 3 fins are straight as as arrow!
These are all 3 fin rockets.
[video=youtube;iZwMpT3Q9lk]https://www.youtube.com/watch?v=iZwMpT3Q9lk[/video]
[video=youtube;yrFtBXr-Ea8]https://www.youtube.com/watch?v=yrFtBXr-Ea8[/video]
[video=youtube;sDI8uIqfrjc]https://www.youtube.com/watch?v=sDI8uIqfrjc[/video]

4 fin rocket:
[video=youtube;sVNMhO7td84]https://www.youtube.com/watch?v=sVNMhO7td84&t=6s[/video]
 
One of the reasons that the rockets I have built and flown kept getting larger over time is that I discovered that larger rockets spin less. I build my fin assemblies outside of the body tube which makes it easier to align the fins. For my YouBee, I created slots in the centering rings to make sure the fins were straight. I think I have to credit the larger size of the rocket more than my building skills, though.

[youtube]vlm6k2qwlK8[/youtube]
 
One of the reasons that the rockets I have built and flown kept getting larger over time is that I discovered that larger rockets spin less. I build my fin assemblies outside of the body tube which makes it easier to align the fins. For my YouBee, I created slots in the centering rings to make sure the fins were straight. I think I have to credit the larger size of the rocket more than my building skills, though.

This seems logical . My camera shroud is hanging on 2"-4" body tubes, and is almost as big as a fin! So, the non-symmetric aero maybe generating spin.
 
I imagined that a camera fastened to the outside of an airframe would unbalance the rocket and cause spin, but Tim's and Roger's videos suggest otherwise.

Is there any standard measure of quality for a video recorder? I know that still camera quality is largely judged by megapixels, e.g., a 10mp camera makes better pictures than a 4mp camera. Any similar measure for video, other than 1080 is HD?

Seems like most people are using external cameras. Jason may be in the minority with his internal Nexus 5X, but he has produced some awesome vids.
 
Wouldn't buy anything less than 1080 otherwise why put a camera on a rocket. Lots of detail.
As far as camera inside vs. outside, its a lot easier to tape a rocket externally than it is to fit a phone in an AV bay. Jason's AV bay is unique and if you've ever seen it, really cramped with the phone and that's in a 4" airframe. Sure you lose couple hundred feet with it taped externally but unless you really care how high you go, you wouldn't be adding extra weight to a rocket anyhow.
 
There are two distinct ways to go: [/FONT]

Here's a vid with two different cameras for comparison.

1. Keychain 808 looking up (this was superglued to one of the red booster fins)
2. Muvi Pro looking out.

https://youtu.be/87BVKLiDqXI

This vid has the Keychain looking down, the Muvi looking out and a Replay HD looking up.

https://youtu.be/G-Iwi-UF2ck

None of these are great cameras, but I think all three work pretty well.

Jim
 
I would agree that anything less than 1080p just isn't worth it. I've mostly flown Mobius ActionCams, flew a U8 (similar to the 808, just a different form-factor, it's shaped like a USB thumb-drive rather than a keyfob) once and was so unhappy with its quality compared to the Mobius that I never flew it again. Beyond video resolution (the 1080 means it's 1080 horizontal lines [vertical resolution], if it's HD the vertical lines will probably be 16/9 higher, i.e. 1920 [horizontal resolution]) framerate is the next thing that matters. The Mobius is 1080p/30(fps), there are newer cameras like the Mobius Mini or Firefly Q6 (my current favorite) that are 1080p/60, so you get twice as many frames per second and therefore smoother video, or ability to do smoother slow-motion video, etc. The cameras that offer higher framerates tend to also offer higher resolution options at the lower framerates, like 2K or even 4K video, personally I prefer >30fps over >1080 resolution). The "p" suffix also means progressive, where the entire frame is taken at once, I'd suggest avoiding anything that ends in "i" as interlaced video shoots half of the lines (even vs. odd) in one frame and the other half in another, so for fast motion it can look pretty terrible, I'm not aware of any of these style cameras that shoot interlaced video. So I wouldn't ignore this suffix but I think you're unlikely to see anything other than "p".

I haven't found a shroud to affect the spin on any of my rockets, having flown Landru's shrouds on both 54mm MD and 4" rockets. If you just go and strap it on with tape (have done this a few times with electrical tape) I'd think that might have a bigger effect just because it's probably going to be bigger, and harder to make smooth/symmetric (and probably flaps about in the wind also). My 4" FG Nike Smoke rotates naturally (I tried to create my own diamond profile shape in the flat FG fins, and clearly wasn't perfectly symmetrical with it), as I'm working on a shroud for the Firefly Q6 for this rocket I'm tempted to see if I can put some features on the shroud to try to offset the spin imparted by the fins, but given the different positions on the rocket I suspect this might turn things into more of a spiral and probably not help as much as I'd hope.

But I definitely prefer down-facing. Most of the shrouds point the camera straight down, it minimizes the profile of the shroud, but also occupies more of the frame with the rocket body. As I design my own shrouds I'm going to try angling the camera away from the body at least a bit, I definitely want to ensure that part of the airframe is still in-frame. And in a DD rocket I'd certainly suggest having the shroud above the drogue separation point, my favorite videos are the ones where you can see the lower part separate at apogee. If you put it on the mid-section the camera will end up pointing upwards during the drogue descent (might even get some good shots of the drogue as well, and gets you a better view once the lower part of the rocket is "out of the way"), then will end up facing towards the ground again once the main deploys, so you can probably see touchdown.

Two example videos, first one is a 4" Excel DD, Mobius ActionCam was attached to the avionics bay (had the vent band lengthened 1" for the Landru shroud):
https://youtu.be/ax9BcakBrmc?t=28s

Second one is a Firefly Q6 that was taped-on to my 4" FG Nike Smoke with electrical tape, I particularly liked this flight both because it was a Vmax motor and it didn't arc-over at apogee, it just started to descend into its own smoke trail, which wasn't obvious from the ground video so it was a pleasant surprise when I reviewed the on-board video afterwards:
https://youtu.be/O6K3ks6h6d4?t=19s
 
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A camera on the outside WILL induce spin if it is not aerodynamically symmetrical. For example, if an 808 is taped on at a slight angle. Or if the tape itself is haphazard. I have personal experience with both scenarios.
 
Don't get hung up on resolution. Video at 1080p from a small camera with a plastic lens isn't going to look as good as 480p from a camera with a larger sensor and better lens. But, of course, it's easier to attach a small keychain camera to most rockets than a 20 pound, three sensor professional camcorder. And, you'll cry a little less losing a $10 camera than a $3000 one if something goes wrong.

I lost about $500 worth of cameras when a rocket burned up on the pad once. One of them was an action camcorder with a reasonably large sensor and a real glass lens. It took great video (including video of its own destruction.). Since then, I have switched to the less expensive plastic camcorders that sell, now, for around $30 to $50. I like the ones with a traditional camcorder shape. I used to build fancy shrouds to cover them. But, now I just cut a rectangular hole in the ebay of the rocket and line it with a box for the camera. I attach a Velcro strip to the box that wraps around the camera to secure it. This makes it easy to start the camera and insert it in the rocket on the pad (usually standing on a ladder). The shape of the camera allows it to look down the side of the rocket.

I have also been known to just tape a camera to the side of a rocket using electrical tape. Electrical tape works well and you can buy it in a color to match the rocket!

It seems to me that the availability of light, small cameras is one of the things that has helped our hobby over the past decade or so. Being able to record video from a typical model rocket is exciting and may be something that has brought some people into the hobby (or back into it.)

-- Roger
 
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A camera on the outside WILL induce spin if it is not aerodynamically symmetrical. For example, if an 808 is taped on at a slight angle. Or if the tape itself is haphazard. I have personal experience with both scenarios.

I had one rocket go unstable because I mounted a camera too high on a long, thin rocket. The flight was great up to about 400 feet when the rocket must have angled itself just right so that the camera caused to go unstable. The rocket flipped over causing the altimeter to fire the ejection charge while the motor was still burning.

-- Roger
 
A camera on the outside WILL induce spin if it is not aerodynamically symmetrical. For example, if an 808 is taped on at a slight angle. Or if the tape itself is haphazard. I have personal experience with both scenarios.

Not as much as you think!
 
I had one rocket go unstable because I mounted a camera too high on a long, thin rocket. The flight was great up to about 400 feet when the rocket must have angled itself just right so that the camera caused to go unstable. The rocket flipped over causing the altimeter to fire the ejection charge while the motor was still burning.

-- Roger

If anything, that should have made the rocket more stable.
 
If anything, that should have made the rocket more stable.

It was like adding a fin to the top of the rocket. I suspect that I could launch the same rocket with the same configuration and not have the problem. It was probably bad luck that the rocket ended up at just the right attitude that it had such a bad effect.

-- Roger
 
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