Joe Turner's 38mm Scratch-Build

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

Postby joeman » Sun Oct 28, 2018 11:34 am

Decided to work on camera component of payload while I talk to supplier RE: Cable Cutter.

Decided to use 1.5mm Perspex to allow the camera to have visibility of surrounding area, while still trying to keep the rocket aerodynamic.
Eventually decided on having the perspex go the complete distance around the coupler - it looks better and easier to do.

Here are a few photos.

IMG_6660_sml.JPG
Camera in 3-D print payload holder next to payload air-frame compartment.


IMG_6412_sml.JPG
Other side of the payload - just so you can see what is there.


Cheers!

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

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

Postby drew » Mon Oct 29, 2018 5:43 pm

joeman wrote:Finally got cable cutter.
The piston part doesn’t have a sharp end which surprised me a little.


That surprises me too. You ordered the Archetype model, right? FYI the "original" cable cutter that the Archetype model copied used flat cylinders that didn't have a sharp end. But it appears yours are slightly bevelled?

Also, FYI I've never once tied my cable cutter to anything, I've only ever used them attached to an ematch. I've never had one come off the ematch all the way up to 75mm MD (which had two cable cutters).
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 joeman » Mon Oct 29, 2018 5:52 pm

Hi Drew,
Yes it is bevelled and yes it is from Archetype Rocketry

Bob is looking into it for me.

I may try drilling a small crater into each end and try giving it a sharp edge. I’ll see what Bob says first.

Sort of wish I bought two of them now... something to compare against. Oh well.

That is good yours never came off. Knowing my luck it would *g*




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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 » Sat Nov 03, 2018 9:34 pm

Response From Bob

Here is the email from Supplier:
From: Customer Service <scrambled@scrambled.com>
Subject: Re: Re: Aerocon Systems: Welcome!
To: Bob Fortune <scrambled@scrambled.com>

> Bob,
>
> Yes, the cutter now has chamfered edges. The sharp edges really cut into the aluminum if overpowered with too much blackpowder or if the
> o-ring at the end shifts. They cut the same. I have several that I use disposable delrin cutters.

If you're still having trouble with it please contact him. I don't have a picture of the piston but it's identical to the one you sent


Bob


Hope that helps someone else.


Anyhow, I managed to do a good test.

[youtube]https://youtu.be/xiplhJgttTg[/youtube]

Got a lot more confidence with it now.

Cheers

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

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

Postby snrkl » Mon Nov 05, 2018 9:17 am

joeman wrote:Hi Drew,
Yes it is bevelled and yes it is from Archetype Rocketry

Bob is looking into it for me.

I may try drilling a small crater into each end and try giving it a sharp edge. I’ll see what Bob says first.

Sort of wish I bought two of them now... something to compare against. Oh well.

That is good yours never came off. Knowing my luck it would *g*




Sent from my iPhone using Tapatalk


One thing that I usually do (when funds permit) is anything critical, I buy in pairs.

Mostly because it means I have a spare in case I klutz something, but the number of times it’s been useful to have extra parts lying around is amazingly often.

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

Postby joeman » Thu Nov 08, 2018 10:31 am

Wise words Snrkl.

I've been busy making the launch tower. It isn't complete. Still need to:-
- Trim horizontal threaded rods a little at top
- Put in screws to allow one to lock the poles on to the three "feet"
- Attach a rope/harness system to keep it still
- Put "toes" on end of feet to raise the system up a little , and provide place to insert stake.

But reasonably happy with it. Welds are not my strong point, Sometimes I get a good run, sometimes the rod never seem to stop sticking.

IMG_6708_sml.jpg


You may notice a CF tube in the system - trying it out.

One can easily take the three poles off and carry separately.
One will be able to adjust it to suit greater diameter rockets

Cheers

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

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

Postby drew » Thu Nov 08, 2018 12:41 pm

Excellent work Joe! How do you feel about building a tower that supports 4 fin rockets in 54mm and 75mm airframe sizes? :D

I could definitely use one come April... :wink:
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 OverTheTop » Thu Nov 08, 2018 1:37 pm

Excellent work Joe! How do you feel about building a tower that supports 4 fin rockets in 54mm and 75mm airframe sizes? :D

I can lend you an angle-grinder to lop the extraneous fin off :D
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Re: Joe Turner's 38mm Scratch-Build

Postby joeman » Fri Nov 09, 2018 7:16 pm

Drew: I'd quite happily do something up if I lived down that way. Seriously :-). Unfortunately, I am all the way up in Cairns.

I will be travelling light when we come down to Thunda2. Will be sending everything else ahead of our departure.

On the topic of Thunda2, is it a safe bet that there will be a system like this for launching 3-fin, 40mm diameter rockets?

Cheers

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

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

Postby drew » Mon Nov 12, 2018 11:21 am

joeman wrote:Drew: I'd quite happily do something up if I lived down that way. Seriously :-). Unfortunately, I am all the way up in Cairns.

I will be travelling light when we come down to Thunda2. Will be sending everything else ahead of our departure.

On the topic of Thunda2, is it a safe bet that there will be a system like this for launching 3-fin, 40mm diameter rockets?

Cheers

Joe


You're a good man Joe. I've not started down the path of organising my launch hardware needs as I do have options. For my single stage MD attempts I expect I'll bring along fly away rail guides in both 54mm and 75mm form factors to cover if I don't have access to towers. I'm a little hesitant on the 75mm side of things but I've seen Crazy Jim load one up with a reasonable motor (75mm 6G-XL Green) and was successful so I do believe it would work.

Image

That said I do believe a tower would be marginally better from a launch perspective.

My two stage stack will be using rail guides on the booster so I expect copious infrastructure will be available to support that.

At the last THUNDA I used Larry's (I believe it was Larry's) tire rim MD tower. It's a 3 fin design and should suit your needs. Fingers crossed it's still around, here's a pic.

Image
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

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

Postby joeman » Tue Nov 13, 2018 5:35 pm

Lovely! Going to be exciting days!

Perhaps I will need to consider getting this launch tower down south.

Going to have to think up something.

Cheers!
Joe
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 » Tue Nov 13, 2018 5:51 pm

G'day,
I'm looking at possibly doing a Maiden flight using G76-10 motor soon.

I have a 38/29 adapter and it is a VERY snug fit into the air-frame. So much so, I had to sand it ever so slightly to get it in.
It certainly won't come out on its own accord, you need to pull it out with not insignificant force. (But it isn't crazy hard).

IMG_6750_sml.jpg


RE: Thrust/Retention
I have an RMS case and it looks like I can rely upon the rear screw-on closure to transmit the thrust to the air-frame via the Adapter. I think I'll be able to put a healthy ring of masking tape behind the adapter to stop the motor slipping out backwards. Then I'll be able to install the "whole unit" into the back of the rocket. (bit different from what is normally done, but I want to apply tape on the back of motor).

Now, the air-frame has a motor block for CTI motors and it will be "plugged" and I will not be using an ejection charge from the motor. So to me, it looks this should work.

I know the motor will get warm, and the fit might get a bit tighter momentarily, but should be removable once cooled down completely (which is what one does any how).


Any concerns?

Cheers

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

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

Postby drew » Tue Nov 13, 2018 6:20 pm

joeman wrote:Any concerns?


I get worried any time someone flies a hobbyline case with a fairly grunty G like the G64 or G76. I've had two G64's CATO on me, both with the forward closure letting go. I've seen others suffer a similar fate. They're just a bit of a roll of the dice imo.
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

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

Postby joeman » Tue Nov 13, 2018 6:23 pm

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
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 » Tue Nov 13, 2018 10:09 pm

I've done a lot of work on the Tracking device for this rocket.

I'm using :-
- RFD900u
- AdaFruit Ultimate GPS
- Arduino Mini Pro
- UBEC PSU (not pictured)
- Simple 1/4 wavelength dipole
- Yagi for ground base antenna (not pictured)

See photos below.

IMG_6742_sml.jpg
IMG_6742_sml.jpg (118.78 KiB) Viewed 416 times


IMG_6753_smller.jpg
The not so pretty side


IMG_6743_sml.jpg
The nice looking side
IMG_6743_sml.jpg (177.4 KiB) Viewed 416 times



I've done one test so far...about 100m apart on full power. No problems there (didn't expect any). Will try reducing power and see how well it performs. Admittedly the antenna for the rocket is a bit of a "try and see".

I'm not really a fan of hot glue, but it was a good way to keep the radio modem stuck. I also used hot glue to keep some wires where they are meant to be, e.g. Antenna.

Hope someone can get something useful out of this.

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


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