4" Thor L2 build

Before:


After:

Loved my thor, many motor ejection flights... a single dual deploy flight... J380 54mm smokey sam. I remember it like yesterday, first 54mm motor and first dual deploy, worked perfectly for a nice slow cruise to 3-4K'.

Originally posted by jraice
Loved my thor, many motor ejection flights... a single dual deploy flight... J380 54mm smokey sam. I remember it like yesterday, first 54mm motor and first dual deploy, worked perfectly for a nice slow cruise to 3-4K'.

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You said a couple things that are strange, you, "loved", and only one D.D. flight, what happened to it?

I can't wait to stuff a J360 Skyripper in it and send it off. Heck, I can't wait to send it up on the 14th of April, either an Aerotech H148R, or a Loki H144...

Should be fun, then if things go well with the shakedown flight, Loki J528, or a Skyripper J197, or J360, depends on the day I guess.

Nice build it looks good.

"You said a couple things that are strange, you, "loved", and only one D.D. flight, what happened to it?

I can't wait to stuff a J360 Skyripper in it and send it off. Heck, I can't wait to send it up on the 14th of April, either an Aerotech H148R, or a Loki H144..."



True, that is a strange idea but it was my dad and I's first HPR rocket, we didnt really know what we were doing parachute wise and the parachute didnt inflate, slight damage to one fin's attachment. We got some help and flew it maybe 8 more times motor ejection before modifying it for DD. Had one DD flight before flying season ended and it had a few other motor ejection flights after that and the damage was just getting to risky, could have replaced the booster section but instead decided to get a new dual deploy kit (5" polecat) and retire the thor. The polecat is awesome and I have flown it well over a dozen times on motors from baby I's to baby L's.

H144 and H148 should work nice, my stock thor (yours is probably a bit heavier) started out with I161's, nice boost...

heh, for once i'm right. i agree with you, lazyness is PITA i wanted to do Wasp_1 have started but never came close to working thing
https://www.gtba.co.uk/engine_designs/index.htm

mmmmmmmmmmmmmmmmm...Mirror is installed, and the positioon is spot on, should make for EXCELLENT videos!

The flash washed everything out, so I shut it off, kinda dark, maybe better ones later. I have a big bertha nose cone that will be epoxied around the wooden structure. Thanks to my friend cory for giving me a hand.





Hopefully I'll have the super tiny blind nuts installed before I go to bed, and maybe a little bracing to do on the inside and I'm done with the camera!




- Ben

Here's a test of the onboard video...

I need to clean the lens still, and play with the resolution. Also it's a tick dark in my apartment.

https://www.youtube.com/watch?v=k0uTpvkF2lM

Originally posted by RalliART
Here's a test of the onboard video...

I need to clean the lens still, and play with the resolution. Also it's a tick dark in my apartment.

https://www.youtube.com/watch?v=k0uTpvkF2lM

Click to expand...

That is toooooo funny!

During the part where you pick up the rocket and then start pulling the lower tubes off of it, it seems like your simulating deployment on video. I can just hear you making the "WHOOSH" noise of the rocket motor burning in your head as you pick it up off the floor, then the "pop" noise as you pull the tubes apart.

HA!

lol, yeah I was, I wanted to make sure I can see both events, that's why I put the camera in the top section. lol

On a side note I can't wait to fly this thing.

Man today was a busy day of building for me. I glued a Big Bertha nose cone to the side of my camera bay over the mirror.






And that's all I did, see, busy. LOL

Alright did most of the E-Bay today, I need to get some copper end caps for charge holders, then it's 2 more blind nuts, and another screw and the pyro portion is finished.

I M.I.G. welded the stock LOC Eye Bolts:


Main side:


Apogee side:


My Transolve P6K Mounted to a piece of G10, and my arming switch:



I'm going over to McMaster tomorrow to pick up a 9V battery holder, I scrapped my original idea about 5 minutes ago because for $1.97 ea., why work hard? lol #4 is the one:


I'm almost finished, I need 2 nomex sleeves, another 30 ft. of T.N., and the copper end pieces! I'm not sure if it will be painted by launch day (14th) I leave for Vegas on a business trip Monday, returning Thursday. I usually don't paint a new bird anyway, cause if things "happen" why ruin a perfectly good paint job? Perfect example to this is my first L1 attempt with my minnie magg. after this I extended it to 42 inches and left it unpainted because it had character then. lol

https://media.putfile.com/ZipperMagg

Ok Finished the E-Bay, 3/4" copper end caps to hold all the black powder I would ever need for this particular bird. I also put in some 3/16" Landing gear straps to keep the Ematch wires where they need to be.





All I need is another 30 feet of tubular nylon and 2 nomex sleeves.

Ralliart

Build is looking good. That was a great idea with the nose cone for the mirror!!!

Lee

Originally posted by leegscott
Ralliart

Build is looking good. That was a great idea with the nose cone for the mirror!!!

Lee

Click to expand...

Thanks...


I'm hoping the nose cone will cut down on some of the noise from the air rushing by.

Well the nose cone will help aerodynamics, still will have some turbulnce noise due to the air pocket... Still looks awesome! Maybe you will catch the whistle of the dual fin design on video!!!

Thats a sweet looking e-bay! Thats how most of my birds are setup, except with slightly larger terminal strips. I have swapped over to a new design though, normally I use 1" end caps and just put the baggy style charge in it. Now I am starting to use 1/2" end caps which snuggly hold some centrofuge capsules I have. The capsules have a threaded cap and make sweet charge holders. The cap doesnt blow off but the thin center breaks, so there isnt much "shrapnle" flying around (just a small soft rubber disc). The 1/2" end cap is just to hold it secure. I did this on my 54mm MD rocket to help with high alt deployment but I like how it works so much I am retrofitting some of my larger DD rockets with it.

Well I did the ground testing tonight, there was no snow when I started, blizzard when I finished. lol

2 1/16" styrene shear pins in each section, 3 grams of black powder in each section...Big boom...

Here's the video, onboard, and outside.

https://www.youtube.com/watch?v=BhVdZLK5ZjE

The video works now!

Those seem like pretty aggressive charges! I personally just get a large enough charge for clear seperation and then add some for safety, I dont want the force of the charge to pull the line taut, gravity does that for me. If thats how you like it then it will work, for a while, but that seems like excessive force.

The main (nose) didnt look as bad, but thats a larger compartment right?

My thor (older version) had a 34" booster I believe and I friction fit the coupler into it and used 2 grams of BP. It had a loose fitting recovery harness, 24" parachute and some nomex. My upper section was a single full length 34"-36" airframe, cone was friction fit (very tight though) and I went with 3 grams... But I had a R9 in there and it was a VERY tight pack.

Usually when I do a test I never get the lines full extended on the grass, yours not only seem to do that but they hit the end with some force.

Did you use some sort of calc or just guestimate how much BP to use?

So, how many neighbors called the bomb squad after that?

Those do look a bit oversized, especially the first charge, but it will certainly extricate all the laundry...

Ralliart

I have to agree looks like a little to much B.P. to me. I used 2g on my 4"Thor and I thought it was a little much. I believe that 1 1/2 would be plenty. You might give it a try.

The snow was a nice touch, 70 degrees here in California.

Lee

But the booom...lol

Yeah I'll do 2 grams at the launch next week. that will wor for me...

It will be 80 in Vegas next week, can't wait.

holy crap! in my 4" rockets I usually use between 1-1.5g of BP, I always ground test... but I use 1 4-40 nylon sheer pins to hold 'em together.

Originally posted by cjl
So, how many neighbors called the bomb squad after that?

Those do look a bit oversized, especially the main charge, but it will certainly extricate all the laundry...

Click to expand...

lol, none came...

Originally posted by Brian Barney
holy crap! in my 4" rockets I usually use between 1-1.5g of BP, I always ground test... but I use 1 4-40 nylon sheer pins to hold 'em together.

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I'll knock it down to 2 grams...lol, I wasn't sure how much was necasarry...lol I went high obviously...

if your knocking it down, be sure to do another ground test, 2g should pop the 2 sheer pins, but you dont want it to not pop them.. theres a guy in my club who always likes to put huge charges in his rocket.. afew years back he was prepping his rocket and the ejection charge went off.. shot his nosecone through the top of his ezup and it tore a big hole. prolly scared him and everyone within 200 yards of him pretty good.

Yeah I'm going to retest the booster one only, the main charge seemed good @ 3 grams...

Use of a single (or any non symetrical shear pin arrangment) is very risky! I would advice swapping down to 2-3 2-56's and retesting... Using one pin can bind the joint and you can get a failed, or under-forceful ejection. The side without the pin is moving fine, the side with it has the resistance of the pin, this can cause binding between the airframe and the coupler/should.

Originally posted by Brian Barney
holy crap! in my 4" rockets I usually use between 1-1.5g of BP, I always ground test... but I use 1 4-40 nylon sheer pins to hold 'em together.

Click to expand...

Originally posted by RalliART
I'll knock it down to 2 grams...lol, I wasn't sure how much was necasarry...lol I went high obviously...

Click to expand...

As a general rule, on rockets up to 4" in diameter, I start with one, and then work my way up with .5 gram incrememnts. Anything bigger and I start with 2 grams and work my way up in 2 gram increments.

try out the three equations on rocketryonline (two equations and one calculater, one equation is the same as the calc) and then pick an amount in that range. I test that range and if it works decently I just add a small amount in when I actually fly the bird. Usually I will do about 25%-50% more BP for the actual flight then what I calculated with the equations and tested with. This is just because there are some uknowns when actually flying... The rocket isnt stationary so there could be bindings etc...