38mm Level 2 Minimum Diameter Build Thread - "The Spanish Inquisition"

[ScrapDaddy]

I am taking a break from odd-rocs a bit and wanted to do something that would go a little bit higher for my level 2 (my level 1 went about 250 feet), and so I've decided I wanted to do a minimum diameter build for my level 2, which I'm planning to attempt sometime next spring. I've also decided that for 38mm and up my wallet's loyalties will lie with Loki (that 1500ns 38mm motor looks fascinating...)I'm still in the theoretical planning stage right now and had a few questions upfront:

1) What's the general preference for minimum diameter shock cord mounts? I was thinking about sliding a centering ring part way down the body tube and tying the shock cord to that, but I'm not sure.

2) With regards to friction fitting is there general advice besides using that metallic duct tape and giving about an inch at the back to do an external wrap?

 

[Salvage 1]

I have used a couple of short couplers with a bulkplate between them... fix this in the BT above your fore closure and you should be able to put a eyebolt through it into the screw of the foreward closure.

Good luck.


The ONLY thing that i see that may be a problem.... the name.... how many times will you have to go back out and come in again coz you forgot a step?

Cardinal Fang........

 

[rharshberger]

And here I thought you were referring to this inquisition...

[video=youtube;NUMkcBctE7c]https://www.youtube.com/watch?v=NUMkcBctE7c[/video]

On the serious side though, for shock cord attachment I woud use an welded eyebolt on the motors forward bulkhead and the motor friction fitted with a wrap of metal duct tape (aka CJ's method).

 

[captbk]

I have a Go Devil 38 and I went with the slimline retainer but I'm going to be building another this winter and I'll be going with CJ's method mentioned by Rich above. Also I went with fly away rail guides. Ive flown mine to just under 10 thousand ft. on the Loki J712. Plan for the biggest motor you plan to fly and go bigger and you WILL need a tracker. I've had a AT 1080 case in mine and there is very little room left for shock cord. Go devils will take anything you put in them. Good luck on your level 2.

 

[LithosphereRocketry]

This is revenge for my teasing about my rockets outflying yours isn't it...

Should be fun- I'm considering a bit of Loki someday. Can't beat a sparky G for under $20...

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[LithosphereRocketry]

It just occured to me that, not including documentation requirements, you could do L1, L2, and L3 on a 54mm MD... Loki being Loki they have a 54mm baby M.

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[Salvage 1]

It just occured to me that, not including documentation requirements, you could do L1, L2, and L3 on a 54mm MD... Loki being Loki they have a 54mm baby M.

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You talking about that M1378??

Not many places in the US that you could fly that one minimum diameter!

 

[markkoelsch]

You talking about that M1378??

Not many places in the US that you could fly that one minimum diameter!

View attachment 329730

Exactly. I think it is three places. Black Rock, Argonia, and I seem to recall maybe Montana having a waiver that could support that ( they only activate that if they need it).


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[Buckeye]

250 ft for Level1? Geez, why bother? :wink: Get ready, your 38MD on a J motor is gonna go 2 miles. Tracker is a must.

Search for the Blackhawk38 build thread by Crazy Jim, Lots of good ideas in there that I used on my BH38:

1. An eyebolt in the forward closure is a great harness mount. The eyebolt epoxied into the CTI closure works just fine.
2. A length of coupler retained by screws is also a good harness mount.
3. I used #8 set screws for all attachments, so no screw heads messing up the MD.
4. I squeezed the altimeter sled between the threaded rods - one above the sled, one below the sled - not on the plane of the sled as in the traditional way.
5. Friction fit with the all important wrap of aluminum tape. The tape inside the tube does very little to retain the motor. The outside wrap does most of the work.

 

[watheyak]

Exactly. I think it is three places. Black Rock, Argonia, and I seem to recall maybe Montana having a waiver that could support that ( they only activate that if they need it).


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Arizona! 50k' at Eagle Eye.

 

[mpitfield]

Aeropack MD retainer is also another good option. Good luck

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[Cl(VII)]

I know friction fitting works, and the tape ring works, but I personally don't like them. I used something similar to an Aeropak MD retainer on my GoDevil 38 that I flew on the Loki K627, but that left about two inches of space for the drogue cord. I used 1/8" kevlar, and let it fall drogueless to fit in that space. My retainer took up less room than the Aeropak, so you may be stuck if you want to fit the Loki 38-1200 in a kit like the GoDevil. If you go scratch build then the Aeropak is an awesome option.

How I did motor retention:https://www.rocketryforum.com/showthread.php?142435-Go-Devil-38-on-a-Loki-K627-or-How-I-Leaned-to-Stop-Worrying-and-Love-3D-Printing&p=1725739#post1725739 You could do something similar with a wooden bulkhead too.

 

[Handeman]

I am taking a break from odd-rocs a bit and wanted to do something that would go a little bit higher for my level 2 (my level 1 went about 250 feet), and so I've decided I wanted to do a minimum diameter build for my level 2, which I'm planning to attempt sometime next spring. I've also decided that for 38mm and up my wallet's loyalties will lie with Loki (that 1500ns 38mm motor looks fascinating...)I'm still in the theoretical planning stage right now and had a few questions upfront:

1) What's the general preference for minimum diameter shock cord mounts? I was thinking about sliding a centering ring part way down the body tube and tying the shock cord to that, but I'm not sure.

2) With regards to friction fitting is there general advice besides using that metallic duct tape and giving about an inch at the back to do an external wrap?

I'm not sure about the preferences for shock cord mount. I do use friction fitting on one of my rockets and found that you usually need less friction then you think.

As for MD for L2, I would recommend you do a 54mm MD. If you do a 38mm you are pretty much stuck in the J range. If you really want to fly L2, go with 54mm and be able to fly the J, K and baby L motors.

 

[mpitfield]

I know friction fitting works, and the tape ring works, but I personally don't like them. I used something similar to an Aeropak MD retainer on my GoDevil 38 that I flew on the Loki K627, but that left about two inches of space for the drogue cord. I used 1/8" kevlar, and let it fall drogueless to fit in that space. My retainer took up less room than the Aeropak, so you may be stuck if you want to fit the Loki 38-1200 in a kit like the GoDevil. If you go scratch build then the Aeropak is an awesome option.

How I did motor retention:https://www.rocketryforum.com/showt...ng-and-Love-3D-Printing&p=1725739#post1725739 You could do something similar with a wooden bulkhead too.

Good point on the space restriction. The two 38mm MD builds I did have more than enough room for recovery, but my 54mm MD build is really tight, I could have used another .25". I saw your design on your build post, nice simple design.

 

[ScrapDaddy]

A bit of a teaser, I got a nice package in the mail from Nat at Upscale CNC today.... the contents of the package solve the issue of the minimum diameter retention and also helps with the tracking issue...

 

[ScrapDaddy]

Sorry guys been busy, haven't been able to build or update the thread.

Here were the contents of that package:


Those centering rings seem quite large... Like 10 inches large....

 

[ScrapDaddy]

So this is where I tell you guys I am no longer taking a break from odd-rocs and reveal to you why this rocket is named the Spanish Inquition.

I first glued the Aeropack retainer to the end of the tube so that there was a nice flat surface for the smaller centering ring to butt up against:


Then I slid the smaller centering ring down so that it was perpendicular to the end of the tube:



The smaller ring was allowed to dry before the larger 10 inch ring was also slid onto it:

 

[ScrapDaddy]

Another smaller ring was slid on top of the larger ring to form a nice plywood sandwich:


At this point some of you might see where this is going...


A smaller ring was glued in place about 12 inches above the first 10 inch centering ring:


And another 10 inch ring was added on top of it once it was dried and firmly in place:


A final smaller ring was added to sandwich the 10 inch ring:

 

[ScrapDaddy]

The shock cord was mounted using a 3D printed thingy from Apogee, which was epoxied about 14 inches down the tube:


The whole thing was sealed with laquer to prevent warping:



And for those of you who haven't completely gotten it yet, this is what the naked rocket looks like right now:


And that is why it is called the Spanish Inquisition, Its a "38mm minimum diameter rocket" that no one expected... :eyeroll:

 

[LithosphereRocketry]

The shock cord was mounted using a 3D printed thingy from Apogee, which was epoxied about 14 inches down the tube:
View attachment 330350

The whole thing was sealed with laquer to prevent warping:
View attachment 330351


And for those of you who haven't completely gotten it yet, this is what the naked rocket looks like right now:
View attachment 330352

And that is why it is called the Spanish Inquisition, Its a "38mm minimum diameter rocket" that no one expected... :eyeroll:

Wow...

Now you need to add an extra spool layer every time you fly it. "Among our many (drag-inducing) weaponry..."

 

[markkoelsch]

Does it come with a comfy chair and poking by soft pillows.


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[Buckeye]

Get ready, your 38MD on a J motor is gonna go 2 miles. Tracker is a must.

Now that I see where this going, I retract my statements.

Ugh, I must avert my eyes. Minimum diameter blasphemy!

 

[stealth6]

I gotta say......I didn't expect that.

s6

 

[markkoelsch]

Please do not refer to it as minimum diameter- your interpretation is somehow wrong [emoji3]


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[Cl(VII)]

And that is why it is called the Spanish Inquisition, Its a "38mm minimum diameter rocket" that no one expected... :eyeroll:

Well played. Sick, but well played.

 

[Handeman]

Kind of a super spool. Very cool!

 

[ScrapDaddy]

It flew for the first time yesterday, once on a H268R and once on an I200W. Both flights were significantly higher than expected. My Super Flying Umbrella only hit 250-300ft and the Spanish Inquisition has a similar frontal surface area so I was expecting about the same, but it actually hit about 700-800 feet on both the I200W and H268R, and I'm not too sure why it went so much higher than I expected. If any one has an idea let me know, both the umbrella and this rocket a frontal surface area of about 120 square inches.

Here ae a couple pics of the I200W flight:


I didn't take any during the H268R flight since it was my first large redline and pictures don't do them justice so I just paid attention fully...

 

[LithosphereRocketry]

It flew for the first time yesterday, once on a H268R and once on an I200W. Both flights were significantly higher than expected. My Super Flying Umbrella only hit 250-300ft and the Spanish Inquisition has a similar frontal surface area so I was expecting about the same, but it actually hit about 700-800 feet on both the I200W and H268R, and I'm not too sure why it went so much higher than I expected. If any one has an idea let me know, both the umbrella and this rocket a frontal surface area of about 120 square inches.

Here ae a couple pics of the I200W flight:
View attachment 330499

I didn't take any during the H268R flight since it was my first large redline and pictures don't do them justice so I just paid attention fully...

Those were.... interesting flights.

My guess on the higher altitude is that the Umbrella is pretty light, so it pretty much flies like a feather. This has another 3ft worth of bluetube adding extra weight, so it flies almost like a real rocket.

Here's my big flight for the weekend... Highest of the day actually.
[video=youtube;8FsVxMhPEPQ]https://www.youtube.com/watch?v=8FsVxMhPEPQ[/video]

 

[ScrapDaddy]

Now that it's gotten her sea legs under her, I thought it is now time for me to start really breaking her in. In honor of this, my 38mm+ Rocketry life has been sworn to Loki:





Launch at CRMRC is this Saturday unless the gods intervene...

I'm wicked excited to launch my first ever sparky (I316), but I'm also terrified I'll burn the entire stockpile in one go... (2x I405, 2xI316, 1xI210)

 

[LithosphereRocketry]

Now that it's gotten her sea legs under her, I thought it is now time for me to start really breaking her in. In honor of this, my 38mm+ Rocketry life has been sworn to Loki:


View attachment 332230


Launch at CRMRC is this Saturday unless the gods intervene...

I'm wicked excited to launch my first ever sparky (I316), but I'm also terrified I'll burn the entire stockpile in one go... (2x I405, 2xI316, 1xI210)

(Tries not to drool on phone)...

I may or may not have a 38mm project in the works...

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