Joe Turners L2 Build Thread

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SpaceManMat
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Re: Joe Turners L2 Build Thread

Postby SpaceManMat » Fri Dec 22, 2017 8:36 pm

Looks good Joe.

For the decals I got I supplied photo shop files (PSD). But I think he should be able to convert most formats.
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 Turners L2 Build Thread

Postby joeman » Sun Dec 31, 2017 6:37 pm

Cool thanks. Ok Matt. Will try and provide PSD. (Will also print out before hand on printer to see how they might come out).


Did some of the paint job yetereday. Nose Cone/Payload came up mostly okay.

Air-frame (booster) not so good. Having difficulties between the fins, getting enough paint to them without over-spraying the fins themselves.
The siphon spray gun with only ~550ml didn't help either, so looking at getting a Gravity fed spray gun. Plan is to sand the booster, re-applying 1 or 2 more base coats and then a few clear coats.

Here are two pics.

IMG_4433_small.jpg


IMG_4432_small.jpg


I was a bit smarter this time setting up painting area, using packing tape to drop some plastic sheets from the garage door. Did mean that I had a lot more of the paint flying back in my face.
L1 - Callisto (H133) - 11-Jan-2016 - LCO
L2 - March Fly (1633K940) - 18-Mar-2018

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Re: Joe Turners L2 Build Thread

Postby joeman » Mon Jan 01, 2018 12:53 pm

Hi,
I have a question about HPR safety code...just getting myself up to speed so I can hopefully go for the LCO and then L2 course.

In the doc APRO-002-AMRS-HPR-Safety-Code-rev1-20120701
It says:-

2-13.2 A person shall not locate a launcher closer to the edge of the launch site than one-half the minimum launch site dimension stated in Table 2-13


Let's just assume I'm using an H motor, that there is no highway or occupied building for miles and let's assume I have a circular field to launch in, diameter = 1500 ft then theoretically the launcher should be at the centre of the launch site.

Is that correct?

Now, I'm also looking at:-

http://www.nar.org/pdf/HP-question-pool.pdf

C3) The minimum launch site dimension for your field is 1500 feet. Assuming no public highways
or occupied buildings in the area, what is the minimum distance between the launch site
boundary and the launcher for a 320 Newton-second motor?
A) 100 feet
B) 320 feet
C) 750 feet
D) The launcher may be located anywhere on the launch site to compensate for wind
-----------------
The answer is “A“. The launcher shall be no closer than the Minimum Personnel Distance from any
boundary of the launch site, and the Minimum Personnel Distance for an H motor (320 N-sec) is 100 feet.
Refer to Section 11 of the NAR High Power Rocket Safety Code and NFPA 1127, paragraph 4.15.4.



They seem to provide different types of advice. A bit confusing.

Cheers

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

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Re: Joe Turners L2 Build Thread

Postby SpaceManMat » Mon Jan 01, 2018 10:04 pm

The Minimum Personell Distance is much smaller than the size of the field, so you can move the launcher around on the feild as needed. But you cannot get closer to the edge of the feild than the Minimum Personell Distance as you need to be able to ensure no one will be put at risk by being too close to the launcher.

Minimum Personell Distance and minimum feild size are seperate requirements, but both need to be taken into account when choosing where to launch a rocket for a given size motor and given altitude.

Hope this makes sense.
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 Turners L2 Build Thread

Postby joeman » Tue Jan 02, 2018 12:06 pm

Thanks Mat.
Yes, that is how I interpreted it. It seems logical, it make sense.

I found :-

2-13.2 A person shall not locate a launcher closer to the edge of the launch site than one-half the minimum launch site dimension stated in Table 2-13

a bit confusing. Wrong? Or just an additional rule for the AMRS HPR code?
L1 - Callisto (H133) - 11-Jan-2016 - LCO
L2 - March Fly (1633K940) - 18-Mar-2018

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Re: Joe Turners L2 Build Thread

Postby joeman » Sun Jan 14, 2018 11:52 am

Finally did the on-line Exam for L2. All passed!

Still waiting on Parachutes(on Back Order) from AusRocketry to allow me to do ejection tests.

Looking at purchasing :-

https://ausrocketry.com.au/motors/reloa ... it-18.html

1633K940-18A (WT)

Sim says it will get up to 1267 meters (4155 ft)...well below the 5000 ft ceiling.

I'll give you a quick call tomorrow Blake.

Cheers

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

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Re: Joe Turners L2 Build Thread

Postby joeman » Fri Jan 26, 2018 8:54 am

Learning so much from this project.

I've been examining the clear-coat finish using an eye piece. I could see that the surface is undulating. It has what is termed Orange Peel; where the surface looks like the skin of an orange. It probably isn't the worst Orange Peel, but nevertheless, it certainly isn't flat.

So, I decided to try and sand and polish it.So far, I'm pleasantly surprised with the results.

I used 1200, then 1500 and finally 2000 grit sandpaper to sand it.

IMG_4540_sml.jpg
The sand paper that I used


I used a rag to occasionally dry the airframe to see how the speckled appearance was going. Eventually I got rid of it. Of course, now it was dull, but it was uniform in appearance.

Next I applied some Polishing compound.

IMG_4532_sml.jpg
About to polish...


You will notice in the pic above that the surface is dull on left-hand side and shinier on the right-hand-side....just as a comparisoin.


Later on, doing the fins, I did a comparison between two of them. The improvement is obvious.

IMG_4537_sml.jpg
NOT-SO-Good reflection of workshop items in the fin.(un-polished)


IMG_4536_sml.jpg
Good reflection of workshop items in the fin. (polished)


The aim of this is more than cosmetic, I'm trying to reduce the skin friction drag.

Hope that helps someone.

Hope to start assembling the shock-cord this weekend/next week so that I can start performing ejection tests. Getting a lot closer!
L1 - Callisto (H133) - 11-Jan-2016 - LCO
L2 - March Fly (1633K940) - 18-Mar-2018

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Re: Joe Turners L2 Build Thread

Postby joeman » Sat Jan 27, 2018 10:12 pm

G'day!
Wondering if this logic seems right regarding shock-cord lengths....done some research already, but thought I'd touch base.

I've seen the shock length to rocket length ratio of 3 to 5 being popular. I've already noted that the Wildman rocket which is similar in size to the one I'm building suggest :-
- booster airframe shock-cord ~ 8.2m
- payload airframe shock-cord ~ 5.5m

The rocket is about 2.5 metres in length...giving a ratio of approx 3.3... So that is good enough.
For the air-frame payload bay, 5.5 metres means a ratio only just over 2....considerably less than the 3 to 5.

I've had a think about this and I can justify this in two ways.
1. We want to minimise chance of the nose cone impacting the booster when the main parachute deploys
2. The payload air-frame cavity is 16" (the booster air-frame cavity is 29" long)...and so less charge is required to get same pressure, so the energy to be dissipated by the shock-cord is less, so the shock-cord does not need to be as long.

Does this seem like a fair way to justify this?

Another question, does the ejection charge damage tubular nylon much? Thinking Kevlar might have been a better choice...though I suspect the TN should last a few flights.

Cheers

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

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Re: Joe Turners L2 Build Thread

Postby SpaceManMat » Sat Jan 27, 2018 10:25 pm

Joe, it’s about as short as you could possibly get away with. You need to carefully set your charges so it doesn’t cause an issue, motor deployment could be an issue here due to not being able to test it. I would not go so short, a longer cord will give more time for the kinetic energy to absorbed by drag. Short means a big jolt when the cord runs tight and high stress on components.
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 Turners L2 Build Thread

Postby OverTheTop » Sun Jan 28, 2018 9:06 am

[youtube]Another question, does the ejection charge damage tubular nylon much? [/youtube]

I use TN, but the sections near the deployment charges are sheathed by nomex protectors. That section of TN is also considered consumable to some degree.

I would also z-fold the harness. There is a discussion on my L3 build thready on how I typically set up my harnesess:
viewtopic.php?f=6&t=4612&start=78
TRA #13430
L3
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Re: Joe Turners L2 Build Thread

Postby joeman » Mon Jan 29, 2018 5:37 pm

Thanks Guys.

I'll experiment with how much TN I can comfortably install into the Payload Air-frame (the smallest volume) and look at increasing the length a little. If I can add 0.5 to 1 metre to each length, then I'll do that.

Excellent post OTT. Lots of useful tips. Yes, I had seen someone use have z-folds taped up, looked like a very good way of organising things as well as slowing the release of the parachutes (and so reducing the forces).

Cheers!

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

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Re: Joe Turners L2 Build Thread

Postby joeman » Sat Feb 03, 2018 11:29 am

Wow.
I think I underestimated the time required to get all the shock-cord lines readied and parachutes packed in. Though it is my first time and have to do a bit more work first time round.

The parachute protector is 12x12" and it is only just doing the job for the large parachute. It should protect the bottom part sufficiently until everything is pushed out. (Though I'm thinking a slightly large parachute protector wouldn't hurt!)

I've managed to fit 6 metres of shock-cord in the payload air-frame compartment. Then went the shroud-lines and then the parachute....then 1.25 metres further up the cord is the Nose cone. The Apex of the parachute will be the first part to see the light of day during ejection.

I had to use a rubberband to keep the parachute and parachute protector rolled up enough. Then as I was pushing it in, I removed the rubber band. It is fairly snug. Had no issues putting Nose-Cone on.

Now to do the drogue parachute - that should be a bit easier - larger compartment, smaller amount of material to pack.

Think I'll do a few more trial installs before I start doing the ejection test.
L1 - Callisto (H133) - 11-Jan-2016 - LCO
L2 - March Fly (1633K940) - 18-Mar-2018

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Re: Joe Turners L2 Build Thread

Postby joeman » Sat Feb 03, 2018 6:03 pm

G'day!
Early in the thread, I mentioned slack in the motor casing - moving around a little.
Str8up mentioned that the motor closure screw-on cap would not screw as much on because of the fuel and this would take up the slack.
I've had a bit more of a look and I'm not so sure. Thought it was worth revisiting in anycase...easier to remedy (if required) here, rather than doing on site. [I'm sure it isn't a major issue - I can always make up the gap quite easily. ]

Anyhow, I thought I'd post a little video... as words (describing the issue) sometimes doesn't cut it.

https://youtu.be/CTMduBcobQ8

Let me know your thoughts.


Cheers

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

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Re: Joe Turners L2 Build Thread

Postby joeman » Sat Feb 03, 2018 6:17 pm

RE: Parachute Protector

For the large parachute (Cert-3 Skyangle), decided to just insert the parachute protector before it in the tube....rather than trying to "package" up the parachute inside it. I should still provide a very good barrier. The parachute expands to fill the whole diameter of the tube...forming somewhat of a seal.

So I have:-
- Shockcord with wool/polyester sheath that I made up
- Shock-cord z-folded
- Parachute protector
- Parachute shroud lines
- Parachute
- Remainder of shock cord


Only thing I'm debating is whether I should try and protect more of the z-folded shockcord by moving the parachute protector further down. I have the first foot of the shock-cord in a sheath and the rest is unprotected.
on the other hand, as OTT has said...consider it a consumable. Inspect every new flight and replace as required.
L1 - Callisto (H133) - 11-Jan-2016 - LCO
L2 - March Fly (1633K940) - 18-Mar-2018

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Re: Joe Turners L2 Build Thread

Postby joeman » Sun Feb 04, 2018 1:22 pm

G'day,
Did ejection test for main parachute.

Decided to put in 1.8 grams. But just wasn't enough... (I really did think it would probably be sufficient).
The main parachute weighs ~1kg and is snugly fit and I think this makes a real difference - friction as it is pushed (And pulled) out of the airframe compartment.

https://youtu.be/SPBfHEZJ7Jk

Debating to myself how much additional charge is required.

Fortunately the sheath I made to protect the shock-cord proved itself.
L1 - Callisto (H133) - 11-Jan-2016 - LCO
L2 - March Fly (1633K940) - 18-Mar-2018


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