Modifying my Minie-Magg for an L2 certification flight

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MetricRocketeer

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Hi everyone,

I am currently L1 certified, which I achieved on a LOC/Precision Minie-Magg. I would like to attempt an L2 certification flight on a modified version of this Minie-Magg, one whose length I have extended. I have attached two OpenRocket files to show you my idea. One OR file shows a fairly accurate rendition of my current Minie-Magg, and the other OR file shows you my plan for an extended-length Minie-Magg.

I am not planning anything complex. My current airframe measures not quite 61 centimetres. I would like to buy an additional airframe of about 30 centimetres along with a tube coupler measuring about 20 centimetres to combine the original airframe with this new airframe. I don’t like to use fiberglass. As I understand the procedure, the tube coupler would go inside the airframes. The aft end of the tube coupler would go inside the forward end of the original airframe, and the forward end of the tube coupler would go inside the aft end of the new airframe. I would epoxy everything together.

I would continue to load all the laundry — the parachute, the Nomex, and the shock cord — into the original airframe.

As you all know, of course, for an L2 flight, I would need to fly this on either a J-, K-, or L-impulse motor. I would prefer J. I just want to go low, slow, and pass.

So, this plan makes sense, doesn't it?

Thank you.

Stanley
 

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Since I now have to fly a more powerful motor, I wanted to add a little more mass to the rocket to keep its altitude down.

Also, I just wanted to have a somewhat different rocket than the one on which I flew my L1.
 
I’m not where I can download and view your ork files right now. What do the sims look like for a J motor?

If the altitude is going to be very high, then you might want to opt for a dual deploy setup, and instead of a tube extension and coupler, you would use an electronics bay where the coupler would go and a forward airframe tube as the payload bay or chute bay. One advantage is that you don’t epoxy the electronics bay or coupler into the existing airframe, so it’s fully removable, and you can continue to fly it in its current short L1 form, or add in the dual deploy section and fly it in the long L2 form. And you can also fly it in the long form, even if you opt not to do a dual deploy flight. Very versatile. Here is a link. https://locprecision.com/product/electronic-bay-with-payload-tube/

Another option if you like the longer format, but you are not interested in dual deploy is to add in a removable payload section. It’s basically the coupler and the extra airframe section you mentioned, plus a bulkhead and eyebolt. You epoxy the coupler into the aft end of the new airframe section, but do not epoxy it into the old airframe. And you epoxy the bulkhead into the aft end of the coupler to seal off that compartment. You add the payload section to fly it long style, remove it to fly it short style. I have this setup for my Warlock and use the payload section to dump out payloads at apogee. Here is a link. https://locprecision.com/product/payload-bays/ Select the 5.38” size to see a good picture of how it’s supposed to go together — the generic picture for payload bays is not right.

Third option! You buy just the airframe tube and coupler you described, but don’t epoxy it together. Use friction fit or tape to hold it together. Or epoxy the coupler to the new airframe section, but friction fit or tape to the old airframe. I have friends with this setup for their Warlocks. This is exactly the setup you described, but the new section is removable. Just be aware when you do this, or if you do glue it all together like you were talking about, the main compartment with the chute is larger than the original, and you may need to supplement the ejection charge.

One of the great things about LOC is that they sell the kits for removable dual deploy setups and payload setups, so you can easily extend or add functionality to any of their rockets.

And of course, there’s always the BEST option, which is another rocket! Get a Warlock and fly a super simple L2 flight to around 2,000 feet with a J motor.
 
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Just be aware when you do this, or if you do glue it all together like you were talking about, the main compartment with the chute is larger than the original, and you may need to supplement the ejection charge.
Hi ThirstyBarbarian,

What do you mean, please, by supplementing the ejection charge? How do you do that?

Thank you.

Stanley
 
Hi ThirstyBarbarian,

What do you mean, please, by supplementing the ejection charge? How do you do that?

Thank you.

Stanley
On Aerotech motors to supplement the ejection charge, you remove the ejection charge plug/cap on top the motor and add more black powder, then re-install the plug/cap, if its too full use a bit of dog barf and the original white/ivory colored masking tape, tape it tightly. Easy as can be.
 
Hi ThirstyBarbarian,

What do you mean, please, by supplementing the ejection charge? How do you do that?

Thank you.

Stanley

The technique is what @rharshberger described.

If the tube volume is big enough, you need more than the standard amount of black powder to to pressurize the tube volume and make sure the nose cone pops out with enough force to pull out the chute. And pulling the chute out is a bit more difficult if the tube is long. I use extra powder in my Warlock just because the 7.5” airframe is so large.

You can find calculators to help you estimate how much powder you need or ask people with the same rocket what they use. I add an extra 1.5 grams to the standard charges on my Warlock to bring it up to around 3 grams total.

Onc you know how much you need, you can usually add it to the charge well of an Aerotech motor. On CTI, I make a small cup by wrapping a little bit of tape around the very end of the casing and adding the extra on top of the factory charge and then seal it up. Or you can fold it into a small package of tissue paper and tape that to the top of the factory charge.
 
Here is a pict of 4 Warlocks extended in different ways. 2E99583C-CC4A-4F1E-B922-258C4B977465.jpeg
On the left, the pumpkin section is just a spare piece of tube, not glued to anything. He has a friction fit coupler inside that he tapes into place from the inside. Easily removable.

Mine is the red and yellow one. The section with the kind of zigzag pattern is a payload section glued to a coupler with a bulkhead and eyebolt at the aft end. I can remove that and fly it as a standard Warlock.

The green one has a section of black airframe tube. That one is glued to a coupler, but the coupler is not glued into the airframe. Functionally similar to the first one.

The last one is permanently extended like you are talking about with a section of airframe tubing and a coupler permanently glued in place.
 
Hi everyone,

I am currently L1 certified, which I achieved on a LOC/Precision Minie-Magg. I would like to attempt an L2 certification flight on a modified version of this Minie-Magg, one whose length I have extended. I have attached two OpenRocket files to show you my idea. One OR file shows a fairly accurate rendition of my current Minie-Magg, and the other OR file shows you my plan for an extended-length Minie-Magg.

I am not planning anything complex. My current airframe measures not quite 61 centimetres. I would like to buy an additional airframe of about 30 centimetres along with a tube coupler measuring about 20 centimetres to combine the original airframe with this new airframe. I don’t like to use fiberglass. As I understand the procedure, the tube coupler would go inside the airframes. The aft end of the tube coupler would go inside the forward end of the original airframe, and the forward end of the tube coupler would go inside the aft end of the new airframe. I would epoxy everything together.

I would continue to load all the laundry — the parachute, the Nomex, and the shock cord — into the original airframe.

As you all know, of course, for an L2 flight, I would need to fly this on either a J-, K-, or L-impulse motor. I would prefer J. I just want to go low, slow, and pass.

So, this plan makes sense, doesn't it?

Thank you.

Stanley
I'm going to do my L2 this fall with a stock Minie-Magg, a JLCR and an Eggfinder. Under 3,500'. I've already flown it on on an I140W with the chute release. The chute release will keep it close, the Eggfinder is just for insurance. I'm leaving DD for post L2 testing as prep for L3; I consider it overkill for L2 which just adds complexity with more things that can go wrong.

If you want to go low and slow with a stock Minie-Magg, just add a bunch of nose weight. Keep it simple.
 
Simple with extra nose weight is probably the best advice.

Like you, I did L1 with a MiniMagg. Now years later I converted it to dual deploy (shortened booster, inserted LOC e-bay, added home-built RNWS to nose cone with LOC parts). It flew fine on a I154J and recovered perfectly, though in hindsight more thrust would have been better... LCO announced "... ooh, low and slow!".

For L2 (hopefully this summer now that we're flying again at Lucerne), I built a MegaMagg. I used many construction tips from John Coker's great website, so I know it's MUCH more robust than my Mini... I'm not sure my Mini would take a J350... maybe.
 
Just put a J350 in it. Even works in an unmodified Mini-Magg but marginal. With the extension, there will be no problems. My first high power rocket was a Mini-Magg and I confirmed with it in 1989 with a H70 motor.
 
I have to agree with Rocketjunkie.

Did my Level 2 with a stock Mini Magg on an AT J-350W fifteen years ago and it's still flying. Only mod being electronics in the nose.
LEVEL2 CERT.jpg
 
Here's what I did. Way overkill in reality.



I did a conventional DD flight (Raven Alt) and pretty big chute for the main for the rocket weight. Even if you don't watch the whole video, fast forward to 15-ish seconds from the end to see the 1 in a million landing.

It looks like this today (obviously hasn't flown since paint due to the tape still on the rail buttons. . . ).

Depending on the field waiver and general open area, DD is definitely not required, but I do like a rocket that is pretty darn stable, so adding a length of tube wouldn't bother me at all, even if single deploy.

Sandy.
 

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Just put a J350 in it. Even works in an unmodified Mini-Magg but marginal.
I have to agree with Rocketjunkie.
Hi Rocketjunkie and PSLimo,

I appreciate the advice on the J350.

I see that Cesaroni also has similarly impulsed motors like the J357 and the J360. That way, if I cannot acquire that AeroTech motor, I could go with one of those Cesaroni motors. Do you agree with that?

Thank you.

Stanley
 
Hi Stanley,

A stock Mini Magg should have no problem handling any AT or CTI 5 grain 38mm motor and I've flown several in mine.

It will also stay low enough to track the entire flight.

Good luck on your Level 2!
 
Here's what I did. Way overkill in reality.



I did a conventional DD flight (Raven Alt) and pretty big chute for the main for the rocket weight. Even if you don't watch the whole video, fast forward to 15-ish seconds from the end to see the 1 in a million landing.

It looks like this today (obviously hasn't flown since paint due to the tape still on the rail buttons. . . ).

Depending on the field waiver and general open area, DD is definitely not required, but I do like a rocket that is pretty darn stable, so adding a length of tube wouldn't bother me at all, even if single deploy.

Sandy.


God watching that flight at the end made me anxious for a minute lol. Definitely lucky landing.
 
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