Joe Turner's 38mm Scratch-Build

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OverTheTop
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Re: Joe Turner's 38mm Scratch-Build

Postby OverTheTop » Wed Nov 14, 2018 8:45 am

Nice work Joe! Love the double-sided thing you have happening with the modules and veroboard. I see you have held the radio modem in place with hotmelt. It could suffer from a shear failure under vibration. I would suggest just a wrap of electrical tape or a cable tie to pin it down for some insurance.
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Re: Joe Turner's 38mm Scratch-Build

Postby drew » Wed Nov 14, 2018 2:46 pm

joeman wrote:Drew: Noted.

mmm Maybe I'll get a SCR 29mm motor. They are single use, It'll go higher, but we have plenty of space.

I don't want to be rolling my dice with this 5 month project.

Joe

I think that's wise Joe. If it were me I'd be going SCR SU or a CTI 29mm 3 grain, like say a G106 Sparky.
Andrew Hamilton
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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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Re: Joe Turner's 38mm Scratch-Build

Postby joeman » Sat Nov 24, 2018 8:45 pm

Hello,
Does anyone know which item on AusRocketry site is for the "SCR Adaptor Delay"?

There is:-

https://ausrocketry.com.au/universal-de ... -tool.html

But on closer examination it says it is for Aerotech DMS rocket motors.But I can't find anything "SCR"-ish.

Anyone else flown these SCR composite motors and had to reduce delays? Used an alternative tool?

Cheers

Joe

p.s. not a show stopper for Maiden flight as I'm not using ejection charge anyhow, but something that is going to pop up eventually.
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

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Re: Joe Turner's 38mm Scratch-Build

Postby snrkl » Sat Nov 24, 2018 8:54 pm

joeman wrote:Hello,
Does anyone know which item on AusRocketry site is for the "SCR Adaptor Delay"?

There is:-

https://ausrocketry.com.au/universal-de ... -tool.html

But on closer examination it says it is for Aerotech DMS rocket motors.But I can't find anything "SCR"-ish.

Anyone else flown these SCR composite motors and had to reduce delays? Used an alternative tool?

Cheers

Joe

p.s. not a show stopper for Maiden flight as I'm not using ejection charge anyhow, but something that is going to pop up eventually.


There’s two different ones. I’ve got both.

I’ll go dig them out and post pics so you can see the difference.


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Re: Joe Turner's 38mm Scratch-Build

Postby joeman » Sat Nov 24, 2018 9:08 pm

Awesome. Thanks !
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

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Re: Joe Turner's 38mm Scratch-Build

Postby joeman » Mon Nov 26, 2018 9:37 pm

G'day!
Maiden flight conducted at Ingham! SCR G78. Thanks Mario. And thanks to all the spectators for helping me locate it. I was incredibly lucky in many ways!!

Had two issues
- The GPS/Radio module didn't work properly. I suspect this is battery issue; though I had charged the batteries. In any case, I'm going to see if I can replicate the issue (try and learn something else from it) and then I'm going to re-create this hardware. It was a "little" rushed, and I think I can do a better job.

- The parachute didn't inflate, even though the cable cutter did its job okay. The parachute/9x9" Nomex blanket was really tightly packed. Logic was that it would spring apart. I configured the Main to fire at 800 feet. The rocket was tumbling down about 52 feet/second (so approx 15 seconds), so that really should have been enough time for it to inflate.
Only thing I can think of at present is perhaps I should have used a smaller Nomex blanket and "accepted" a little bit of potential parachute "burn". I am sure then that the parachute would be more likely to inflate with a smaller Nomex blanket.
I'm going to have to think about it a bit more.

Fortunately, the spare Nomex blanket did help to reduce the speed (like a Streamer) and this combined with the soft Cane plants plus the strong build meant the rocket it is relatively unscathed!

Here are some pics...

Still_from_Video2_sml.png
Taking off....
Still_from_Video2_sml.png (235.01 KiB) Viewed 1608 times


IMG_6973.JPG
Parachute/Nomex Bundle. Has expanded somewhat but didn't unfurl/inflate properly.
IMG_6973.JPG (144.16 KiB) Viewed 1608 times


In summary...So while it wasn't perfect, it has given me some good data, and a few things to iron out before Thunda 2019.

Cheers

Joe

p.s. I'm definitely going to install a buzzer next time round.
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

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Re: Joe Turner's 38mm Scratch-Build

Postby SpaceManMat » Tue Nov 27, 2018 8:44 pm

Well this is why we do shakedown flights for certifications...

Not sure about the tracker, OTT might be able o help you there.

It does look like you’ve overlapped your chute, when my protector is a bit big I will fold the side and bottom corner over on themselves first to limit how far around I wrap my burrito. This also can be used to create some extra protection from charges. Keep in mind however that I’ve not used a cable cutter before. Perhaps some pictures of how you wrapped it? I’m also Interested in how this is done for future MD single break DD I’d like to do (cause single deploy over 13k feet is really pushing it).
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Joe Turner's 38mm Scratch-Build

Postby Sirbrad » Tue Nov 27, 2018 8:53 pm

I always attach the nomex blanket to the shock cord about halfway between the chute and rocket body. When the chute bundle ejects the shock cord will pull the blanket free of the chute. Haven’t had any trouble yet with this method.

When using a chute release, I attach that the the chute and then wrap the nomex over the top.


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Re: Joe Turner's 38mm Scratch-Build

Postby joeman » Wed Nov 28, 2018 7:53 am

Hi guys. All good points.

I really like the idea of wrapping it "back" over itself, so the overlap is minimal. That way one still adequately protects parachute, and the surrounding wind only needs to to pry open then Nomex blanket a little to get the processing happening.
Or perhaps I can go for a smaller Nomex Blanket or even resize existing one. (Why restrict myself to a square or certain dimensions).

Matt: Yes, I have photos of folding procedure and I'll upload.


RE: Nomex Blanket - tieing it up.
You will notice that I have TWO Nomex blankets. In the second ejection test, I had the lower 9x9" Nomex blanket covering the bottom of the parachute (which itself had a 6x6" blanket). The aim was that the shock-cord would pull it away JUST as you describe SirBrad, leaving the skirt to provide a bit of drag. I got a bit of a tangle, so I decided to not involve this Nomex blanket with the parachute and instead use it purely as a streamer.
Perhaps I should experiment with the top Nomex blanket and its position on the Shock Cord; just as you do.


Anyhow, I'm in no rush now, I'm going to put a bit more thought into changes and way to test it.

Cheers
Joe
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

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Re: Joe Turner's 38mm Scratch-Build

Postby SpaceManMat » Wed Nov 28, 2018 12:47 pm

Sirbrad wrote:I always attach the nomex blanket to the shock cord about halfway between the chute and rocket body. When the chute bundle ejects the shock cord will pull the blanket free of the chute. Haven’t had any trouble yet with this method.

When using a chute release, I attach that the the chute and then wrap the nomex over the top.


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Good point, I usually attach the protector about twice the diagonal length of the protector away from the end of the chute lines. This also ensures that the protector doesn’t wrap around the lines which could increase your decent rate.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: Joe Turner's 38mm Scratch-Build

Postby drew » Mon Dec 03, 2018 12:51 pm

Hey Joe,

I've been meaning to chime in on your update post shakedown flight but sadly life has conspired to get in my way! Regardless, I've got a few minutes so here we go.

Specifically, I'd like to bring up your nomex blankets and how I suspect you're using way too much. From Top Flight's site you'll see that the 9x9 nomex blanket is designed for 3" airframes which is over twice as much diameter as your 38mm airframe. From the Top Flight site...

Chute Protectors
With Nomex Thread

FABRIC SIZE MAX. TUBE SIZE

FCP-3x3" 1" $4.95
FCP-6x6" 2" $5.95
FCP-9x9" 3" $6.95
FCP-12x12" 4" $8.95

And then you've got another 6x6" in there too? If I were you I'd only be using that 6x6" and even then I'd probably cut it down to 5x5" or even 4.5x4.5". As your shakedown has demonstrated your build techniques are solid enough to where you can most likely recover cleanly without the main deploying. A little char on the nomex blanket and even the chute contained within isn't a huge issue, especially given the Top Flight thin mill chute costs. Normally when I roll my burrito wraps for flights like this I make sure to have ample coverage on the bottom side of the nomex wrap, the side that's facing your apogee ejection charge. Finally, I normally attach the blanket to the attachment point on the NC and not the harness itself as a method for ensuring the blanket doesn't "slide up" the chute shroud lines and causing a sub-optimal recovery deployment.
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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Re: Joe Turner's 38mm Scratch-Build

Postby snrkl » Mon Dec 03, 2018 9:54 pm

snrkl wrote:
joeman wrote:Hello,
Does anyone know which item on AusRocketry site is for the "SCR Adaptor Delay"?

There is:-

https://ausrocketry.com.au/universal-de ... -tool.html

But on closer examination it says it is for Aerotech DMS rocket motors.But I can't find anything "SCR"-ish.

Anyone else flown these SCR composite motors and had to reduce delays? Used an alternative tool?

Cheers

Joe

p.s. not a show stopper for Maiden flight as I'm not using ejection charge anyhow, but something that is going to pop up eventually.


There’s two different ones. I’ve got both.

I’ll go dig them out and post pics so you can see the difference.


Sent from my iPhone using Tapatalk Pro


Apologies for the delay - it’s taken me a while to both remember and then FIND said delay tools...

Image
Image
Image
Image


Main difference is that the AT tool takes JUST the delay grain into the long narrow slot and is drilling the delay directly.

The SCR one for DMS the tool is longer as it has to reach into the DMS motor to drill the delay inside the motor at the back of the charge well...

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Re: Joe Turner's 38mm Scratch-Build

Postby joeman » Thu Dec 06, 2018 8:33 am

Hi Snkl,
Thanks for photos.

Yes, I noticed the instructions for the delay removal tool were in the motor instructions and I did notice that it MUST remove it from the top, since the motor is "one unit".

Where did you purchase the SCR Delay adapter from? I can't see it on any stores. (ausRocketry, scr.... or I'm going blind!)

p.s. I spent a who hour trying to find my spare Nomex Blankets! I know how that feels :)

Thanks Drew!

I had assumed the drag would have resulted in separation. Since the flight, I did try re-wrapping and using ordinary cable tie and then cutting with cable ties, but so far it just falls apart with 9x9". Strange. Perhaps with side cutters I do upset it enough to vibrate it open, not the the ideal way to test, but thought it might be a good way to start...

Theory: I was thinking that perhaps as it falls, the air around a very tightly wrapped bundle can actually hinder the separation somewhat...rather than aide it.
Anyhow, I'll experiment with smaller ones. They are bound to fall away. Was also thinking of adding some Talcum powder to aide in separation and provide a means of spotting during decent.


Thanks for your feedback - Much appreciated.
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

joeman
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Re: Joe Turner's 38mm Scratch-Build

Postby joeman » Thu Dec 06, 2018 10:59 pm

Ok.
I've cut Nomex blanket to about 5" and sewn edges. Still covers everything.

IMG_7058_smaller.jpg


Noticed the shroud lines "stick" a little inside the Parachute, when I simulate a Main deployment with pliers. Talcum powder helps to fix that a little.

RE: Failure of the Tracker
The status LED of the Arduino was blinking madly in Ingham. Naturally, it is faultless here in my house. I've had my father drum into me that, 95% of problems are power supply or the power cable related, so I follow this train of thought. I had 8.3volts -> UBEC -> RAW pin on Arduino. I don't believe this was a particularly clever choice and should have routed it through the Vcc. I know there is a bit of a voltage drop and thought perhaps the voltage was at a level that resulted in some instability. I tried to replicate the issue observed in the field using a diode to bring the voltage down a little further, but alas, I was unable to re-produce it.
I did observe a good sync between the modems while these issues were present, so I believe that it was only the Arduino affected.

Changes to Tracker
1. I've decided to use a single 7.6v LiPO with connectors already attached... previous design had two LIPO with Aluminum contacts.

2. Also going to power the Arduino Raw pin from the LiPO (skip the UBEC). UBEC can supply the 5 volts the RFD900u needs (it doesn't have its own regulator).

3. I've re-jigged things a little with the payload bay 3-D prints...trying to make efficient use of space. Much happier with it!

IMG_7071_smaller.jpg


You can see I used an approximation to the internal space of the Nose Cone to help produce appropriately sized 3-D prints.
(I measured a few dimensions, I know the type of Nose cone and the formula that describe it...and was able to get something pretty close).

design.png


Progress is slow, but there is progress!

Thanks for all your feedback and support.

Cheers

Joe
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

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Re: Joe Turner's 38mm Scratch-Build

Postby snrkl » Sun Dec 09, 2018 1:08 am

joeman wrote:Hi Snkl,
Where did you purchase the SCR Delay adapter from? I can't see it on any stores. (ausRocketry, scr.... or I'm going blind!)



I got mine from AusRocketry.

When in doubt, use the search function on the site.

https://ausrocketry.com.au/scr-adjustab ... -tool.html

Currently out of stock but avail for backorder.



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