Nosecone 1080p VTX

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Arpak

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Howdy! I've been lurking the forums for a bit and figured its time to start being a contributing member of society.

Quick background on who I am to put a story to the avatar, my name is Patrick Cavanagh and I'm currently a senior Computer Engineer at UT San Antonio. I'm the VP of our rocketry club, which is competing in the current Spaceport America Cup, and our mentor is Jim Jarvis. We bug him a lot :D

I've been toying with modifying a Zephyr kit from Apogee to do my bidding, my main intention with it currently is to try to get a dual deploy system out of the single airframe break using a tender descender. I *think* its similar to a HED but slightly different, anyhoo thats a topic for another thread once I work out the kinks in it (read: get it to deploy the main at the right time for a change). Well a few months ago the monthly AARG launch was pushed back and it gave me 2 weeks of free time to stick on a Runcam Split and a 600MW 5.8G VTX into the nosecone. I tossed around the idea for a bit mostly because of the ABSURD price of keychain cameras compared to their sorta garbage quality. Also the club had one to spare :) Photos following.

Here's what the camera shroud looks like, its 3D printed and set to fit inside of the nosecone included with the Zephyr, some 4in long boy. (Next time I'll print it in white ;) )
20210111_190637.jpg


Here is the same shroud but with the Runcam Split sensor installed
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20210111_230041.jpg


Here is what the shroud looks like installed into the nosecone, I scuffed the paint up a bit getting the cut on the nosecone right but atleast I didn't make the hole massive. (Shoutout to using one of Jim's various techniques, in this case using socket head screws to hold body sections together. Works like a dream!).
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Here is what the airframe looks like fully assembled. I did the same flight on an I500 before and after the shroud and only lost about 30ft in altitude, which is nearly a rounding error (or it hit a cloud).
20210112_170943.jpg

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As for the electronics inside the nosecone, well the first time I set it up in kind of a hurry and didn't put too much effort in the sled. Let's call it a proof of concept. Shown from left to right is the inside of the camera shroud and the video cable running to the PCB, the PCB stack for the runcam as well as a Power Delivery Board normally used for drones to deliver a clean 5V to the camera and the full beans to the VTX, attached with the classiest ziptie handiwork is the 500MW 5.8G China special VTX (It does the job), and not shown but velcro'd to the backside of the right panel is a 3S lipo. This assembly was bolted to the extra length of threaded rod sticking out of the bulkhead between the nosecone and the avionics bay.
20210116_195633.jpg


This approach didn't stick long (1 launch to be exact). It was a pain to get the bolt in between the two sections of wood, and attaching the video cable with it flopping around required like 4 hands. I recently got a new 3D printer and wanted to take it for a spin by creating a triangular panelized sled that mounts to the bulkhead from a bolt on the top. The benefit of each panel being separate and bolted together lets me modify each panel separately, which helped with prototyping immensely. Maybe someday I'll print it in one piece to avoid the weight of the bolts, but once I'm more confident in the layout itself.

Here is the first CAD up of the sled. Slight things have changed here and there (mostly fitment and ease of access things), but the overall idea is sound. It prints in 4 pieces, the 3 panels and the top triangular retention piece (this is where the bolt goes through). One panel holds the PCB stack, one holds the VTX and a PCB arming switch (with a longer screw and chewed up threads at the end to hold it in - got that one from lurking posts), and the last panel holds the battery. (More in next post, hit the image limit).


 
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Arpak

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Here are a few photos of it post print and attached to the top of the avionics bulkhead (look ma, no zipties!).
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And finally, the footage. The first time I launched it the onboard SD card had an issue and was unable to save the footage, it ended up being the pins bent slightly making bad contact. It was an easy fix, skinny tweezers and a bit of bending back. Fortunately I had a receiver set up to record the transmitted video, unfortunately the resolution is bad (read: horrible) and its quite static-y. It definitely was a big teaser. You can see in the video how the main deployed itself due to the spin before the tender descender actually pulled it out. A failure, but at least the main deployed (foreshadowing?). To fix the spin I put a swivel between the bulkhead and the fin section, as well as one on the drogue shroud lines. I also started developing the actual chute retaining system (but again, more on that when it... works).

Tuna Cam - Receiver Side Video

The next flight produced much better footage and was meant to be the first test of my chute retainer, although I ran into an issue where the tender descender never fired. Still puzzled on that one, but at this point I think I might've overfilled the BP chamber and forced the ematch down hard enough to break off the coating, the eggtimer quantum did fire the channel but the ematch did not fire and still has continuity/1.2ohms. Weird. I also switched from an 18in drogue to a 12in drogue as it seemed to fall too slow for my liking under an 18 and had the tendency of landing in the single patch of trees at the Hutto site. This caused the fin section to fall slower and get tangled with the drogue, so who knows if it would've deployed regardless of the tender descender firing (I'll be fixing this on the next launch with a different cord order). The field at launch was very soft so I was hopeful in it being fine even under a small drogue but as luck would have it she decided to land tube opening right into the only rock, ouch.
20210206_134531.jpg


Here is the footage from that launch, its honestly stunning and taught me a lot about the dynamics during descent.

AARG February 6th 2021 - Tuna Flight 4 - Failure

As a bonus, here is the same footage but stitched together with the received video and a ground video, it shows the fast difference in quality between the two methods.

AARG February 6th 2021 - Tuna Flight 4 - Receiver vs. Onboard Side by Side

Till next time!

-Patrick
 

Arpak

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Did you have a directional receive antenna for the VTX?
I'm assuming you're talking about on the video receiver side? If so, I'm actually just using a BetaFPV headset a friend gave me for christmas, it has two standard monopole antennas on it. I'd probably be able to get better signal down with a directional one, might be worth looking into.
 

bguffer

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10+ years ago i had good luck with patch antenna and 2.4GHz analog signal through air.


Mounted the patch antenna onto end of stick (receiver, batteries, and capture device were mounted on the board lengthwise). Call it a boom, and make sure you keep the end of the boom/stick pointed at rocket.

Bob
 

Arpak

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Wow! That quality is great for recieved video, I've considered trying 2.4G but haven't looked too much into it so far.
 

bguffer

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Do any technical limitations prevent you from using newer, digital compression/transmission techniques?
"Compared to traditional analog transmission, OcuSync can transmit video at 720p and 1080p which is anywhere from 4 to 10 times better quality, without any color cast, static interference, flickering or other problems associated with analog transmission. Even when using the same amount of radio transmission power, OcuSync transmits further than analog at 4.3 miles (7 km)."

Expense, size of transmitter/camera system, signal characteristics, acceleration issues, other reason? From the above linked site, i suspect the altitude of rocket in combination with type of signal is a problem.

I liked receiving the real time feed 10+ years ago, but shortly afterwards i ditched the real time feed for on-board recording at high resolutions. I never go more than half mile high, and getting higher resolution video was more important to me than recieving real time feed.
When reasonably priced high def transmission becomes possible, i would like to try the real time feed again.

Bob
 

bguffer

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The carnage from my first attempt to use on board camera. Ejection charge failed to separate the rocket, and rocket lawn darted.
1614538453521.png
 

Arpak

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Do any technical limitations prevent you from using newer, digital compression/transmission techniques?
"Compared to traditional analog transmission, OcuSync can transmit video at 720p and 1080p which is anywhere from 4 to 10 times better quality, without any color cast, static interference, flickering or other problems associated with analog transmission. Even when using the same amount of radio transmission power, OcuSync transmits further than analog at 4.3 miles (7 km)."

Expense, size of transmitter/camera system, signal characteristics, acceleration issues, other reason? From the above linked site, i suspect the altitude of rocket in combination with type of signal is a problem.

I liked receiving the real time feed 10+ years ago, but shortly afterwards i ditched the real time feed for on-board recording at high resolutions. I never go more than half mile high, and getting higher resolution video was more important to me than recieving real time feed.
When reasonably priced high def transmission becomes possible, i would like to try the real time feed again.

Bob
For me personally having the split's onboard recording was more important, I threw the VTX on as well just because all of the hardware was practically there, just a transmitter additional.
 
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