SunSeeker II

Discussions on mid/high powered model rockets using F powered motors and above.

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mgaertne
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SunSeeker II

Postby mgaertne » Tue Jan 30, 2018 2:53 pm

As some of you might remember,
my first attempt to fly an O3400 failed after about 0.6 seconds. But, after the crash is before the flight. And you learn by mistakes, don't you.

Now, after a lot of thinking and a bit of design help by Nik and Crazy Jim, I'm nearly ready for a second attempt.
This times, the carbon fiber walls are 2mm thick instead of just one. Also, the epoxy used is a high temperature epoxy, good for approx 2.200 C. This voids the need for metal parts as fin/tip reinforcement. At least I hope...
The rocket is minimal diameter again, built around the CTI Pro98xl casing. The rocket itself is not much longer than the casing, sort of.
Total length is 2.4m with most of the length spent on the 6.75:1 von Karman nose cone. Next is the picture rendered from FreeCad.
test.png
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The darker red part above the motor is the retainer, followed by the drogue department. Not much drogue will be used, just a little sheet to ensure that the rocket will be unstable on descent and that the parts do not collide.
Next is the eletronics bay. It is as small as possible, containing 2 Telemegas, two Lipos and two peregrine CO2 ejection charges.
Nothing more, nothing less. On top of the e-bay we do have the nose cone with the main chute inside.
Flightpath should be apogee at about 18 Km, then the drogue and the main at about 300 m. Max speed is simmed to be mach 3.3, surface temperature will be 700°C at burnout, oh well...
The next pictures are the individual parts and the assembled rocket

Maiden flight should be Thunda Down Under 2. Looking forward to that.

Mathias
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Re: SunSeeker II

Postby drew » Tue Jan 30, 2018 4:06 pm

FANTASTIC!!!

Is that a commercial nose cone or did you make it yourself? Also, is the interior of the NC "empty" for lack of a better term? I can see that you've made the Av Bay out of FGFW so the TeleMegas will have RF comms but the nose looks somewhat underutilised comparatively.

I'm looking forward to your flight at THUNDA 2, aka the rethundering. I doubt I'll hit 60k ft like you plan to, but I might get close. On paper I'm planning a two stage M840 to L265 long burn MD vehicle. Just need to do a shakedown on the design at WWW2018 which isn't too far away all things considered. :D
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Re: SunSeeker II

Postby mgaertne » Tue Jan 30, 2018 4:22 pm

Hi,
I spec'ed and designed the parts but done they were in the US. I just do not have the equipment for handling that high-temp epoxy...
I really can recommend Carolina Composite Rocketry for this.
The body is done in carbon fiber, everything from the ebay up is fiberglass to have radio transparancy.
And yes, the nosecone is hollow. It will house the main chute to save length. I'm just not sure yet if I should use a deployment bag or not for this. It will all boil down to testing in the backyard :-)

Mathias
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Re: SunSeeker II

Postby drew » Tue Jan 30, 2018 5:00 pm

Hi Mathias,

Thanks for the quick response. FYI I'm the guy that received a few of the packets from your TeleMega on your last O3400 attempt.

I too can recommend Carolina Composite Rocketry; Charlie made the HEI forward closures I plan to use for staging at the next THUNDA. I thought those airframes looked too good for homemade but I didn't want to say that. From my perspective Charlie's carbon fibre airframes are the prettiest I've ever seen; they make FWCF airframes look downright pedestrian in comparison!

If you're housing the main in the NC and utilising a dual break/dual deployment (which is what I think you're doing given you wrote the drogue is above the motor retainer) I'd not use a deployment bag as I expect you'll kick the NC off the AV bay for main deployment. If that's the case the main won't be "in the wind" so to speak until it's needed to deploy/unfurl and so I would think a deployment bag would be an unnecessary/redundant feature.

And sorry for the photo below, I, well, couldn't help myself...

Image
Andrew Hamilton
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Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

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Re: SunSeeker II

Postby mgaertne » Tue Jan 30, 2018 5:08 pm

Yes, I remember you :-)
As for the deployment bag, it's not that simple. The nose cone is a bit rough on the inside and the chute is very thin and delicate. There is a chance that it might rip or stuck in the cone... A deployment bag will remedy that.
Disadvantage is that I would need a pilot chute and space is limited.
And yes, of course dual deployment with the nose cone pushed of the AV bay at an altitude. The charges themselves are not redundant, there's no space for that. But the ignitors and computers will be redundant. Even though both are from AltusMetrum, they are not the same hardware. Unfortunately, the same software. However, I calculated that risk to be comparative low against the other risks (such as epoxy glue getting decomposing during ascend).

I'm still looking for two persons willing to track my telemetry. I'd like to have a total of four, two for each computer...
But it is still a long time and I might be able to persuade some germans to come over too for the "expense" of being my crew.

Mathias
Before I forget: the nosecone will be held in place by shear pins...
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Re: SunSeeker II

Postby OverTheTop » Tue Jan 30, 2018 5:27 pm

Hi Mathias. Looks like a great project. Looking forward to seeing it fly at Thunda!

Don't forget to run a thin bead of epoxy on the GPS antenna on the TeleMega. You need to glue the ceramic to the printed circuit part with a thin bead. Under heavy acceleration the antenna can rip off (problem with a lot of GPS units) :cry: It is only held in place by one solder joint and some double-sided tape.
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Re: SunSeeker II

Postby drew » Tue Jan 30, 2018 5:36 pm

mgaertne wrote:Yes, I remember you :-)

I'm still looking for two persons willing to track my telemetry. I'd like to have a total of four, two for each computer...
But it is still a long time and I might be able to persuade some germans to come over too for the "expense" of being my crew.


I nearly offered to help with tracking in my response above but hesitated as I'm planning 3 flights for THUNDA, all of which are high altitude. If I'm being honest I'm being pretty aggressive already with my plans without offering to track another rocket! I might be able to help out though, I'm just not sure. I'll have a fair amount of antennas and AltusMetrum hardware on hand as well if that's of help.

Also, I'm not sure if you're aware, but you can run your TeleMega tracking via an Android phone even if you're using a wired TeleDongle. All that you'd need is a USB OTG host cable, plug one end into your phone and the other into the TeleDongle. It's HEAPS easier than attempting to lug a laptop on your recovery expedition.
Andrew Hamilton
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Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

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Re: SunSeeker II

Postby mgaertne » Tue Jan 30, 2018 5:41 pm

Thanks for that tip. I look into it.
Basically the antennas will be routed through a plastic pipe with a slightly larger diameter to prevent bending and then the pipe will be through the upper bulkhead with very tight tolerances.
Don't have pictures of that yet because it is not built yet. The bulk heads are about to be milled and will ne ready by the end of march.

Andrew, I do not expect other active fliers to help out, they should be too busy by themself. And yes, i do have a BT dongle and a cable based one as of now. I will use a laptop in the base camp and probably a ground plane antenna on a mast for that. The hand held yagies are for the tablet/phones.
But unfortunately the dutch owner of that antenna passed away on Jan first so I might come back to your hardware...
Mathias
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Re: SunSeeker II

Postby Viking » Tue Jan 30, 2018 5:54 pm

Hi Mathias, very nice project, really looking forward to Thunda!
mgaertne wrote:...
Basically the antennas will be routed through a plastic pipe with a slightly larger diameter to prevent bending and then the pipe will be through the upper bulkhead with very tight tolerances.
...

OTT meant the GPS patch antenna.
GPS-Ceramic-Patch-Antenna.jpg
GPS-Ceramic-Patch-Antenna.jpg (4.1 KiB) Viewed 479 times

I used clear heatshrink over the whole PCB for mine, holds the antenna in place nicely and doesn't seem to affect GPS reception, I noticed no difference anyway.
I've never launched anything with the sort of G's yours will experience, but mine did survive a lawn-dart unharmed!
Last edited by Viking on Tue Jan 30, 2018 5:57 pm, edited 1 time in total.
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Re: SunSeeker II

Postby SpaceManMat » Tue Jan 30, 2018 5:55 pm

Great project Mathias, look forward to watching this one let loose.
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Re: SunSeeker II

Postby mgaertne » Tue Jan 30, 2018 6:06 pm

You've me corrected. Should have read the post a bit more thorough. Good idea with the heat shrink tube. will give it a try.
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Re: SunSeeker II

Postby drew » Wed Jan 31, 2018 9:36 am

From my perspective I've never had an issue with the aforementioned GPS patch antenna on my TeleGPS. I know it's a different product but it uses the same uBlox chipset and ceramic patch antenna the TeleMega uses, at least from what I can tell. I've pushed that unit to almost 47Gs with zero modification and it still works a treat.
Andrew Hamilton
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Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

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Re: SunSeeker II

Postby OverTheTop » Wed Jan 31, 2018 11:11 am

I have pushed up past 50G with my TeleMega and it has been ok too. There are reports of the antennas coming off the PCB so I now glue them as a matter of course.

Remember it isn't only the boost accel you need to worry about. The ejection charges can give significant short and sharp jolts to the airframe. Don't underestimate these!
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Re: SunSeeker II

Postby mgaertne » Wed Jan 31, 2018 11:16 am

I can second that.
Usually the ejection charges or the cute opening create much higher g's than the motor will.

Mathias
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Re: SunSeeker II

Postby drew » Wed Jan 31, 2018 11:35 am

I didn't say anything about boost vs ejection charges gents, I only said that I've subjected AltusMetrum GPS hardware to nearly 47Gs without issue.

mgaertne wrote:Usually the ejection charges or the cute opening create much higher g's than the motor will.


Depends on the rocket. I'd posit that MD rockets register their highest G loading during boost and not during chute deployment or ejection charge firing.
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015


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