L2 2nd attempt - LOC Minie-Magg

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beerandrockets

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Hello all,

For my second attempt at level 2, I'm building a LOC Minie-Magg. Pictures forthcoming. This isn't a complete build thread because the rocket went together so quickly that I forgot to take pictures of all the steps. :blush:

First thing I'm really proud of for this build happened before I even opened the package of the rocket. I built a rack out of PVC pipe to hold the rocket while I was working on it.

A few modifications:
-I ordered rail buttons for it to replace the launch lug. The lug is so big that I can use it to build a small rocket all by itself.
-Ordered 18' of kevlar to replace the nylon shock cord. Measured it out to see how close I was to the stock cord length, and the nylon was also 18'.:w:
-Adding a nomex chute protector
-Added 12 oz of nose weight since I plan on flying this with 38mm 5 grain reloads.
-Adding aeropac 38mm motor retainer

IMG_0522.jpg
 
beerandrockets said:
Hello all,

For my second attempt at level 2, I'm building a LOC Minie-Magg. Pictures forthcoming. This isn't a complete build thread because the rocket went together so quickly that I forgot to take pictures of all the steps. :blush:

First thing I'm really proud of for this build happened before I even opened the package of the rocket. I built a rack out of PVC pipe to hold the rocket while I was working on it.

A few modifications:
-I ordered rail buttons for it to replace the launch lug. The lug is so big that I can use it to build a small rocket all by itself.
-Ordered 18' of kevlar to replace the nylon shock cord. Measured it out to see how close I was to the stock cord length, and the nylon was also 18'.:w:
-Adding a nomex chute protector
-Added 12 oz of nose weight since I plan on flying this with 38mm 5 grain reloads.
-Adding aeropac 38mm motor retainer

View attachment 134715
Click to expand...

Good luck with the L2 attempt. Took me, sort of, two tries as well (three tries for level 1)! What happened on your first attempt?

Ben
 
On my first attempt, I was trying to put way too large of an engine in the rocket I was launching. I had to add almost a kilogram of weight to the nose in order to make it stable. Right after the motor burned out, the nose drag separated from the body and kept going so fast that the bulkhead ripped out of the nose cone. The rest of the rocket shredded on impact.

I did recover all the pieces (except the altimeter).
 
You are going to love the Magg still one of the coolest rocket around. Run some simulations no need to make it heaver than in needs to be. When all was said and done after the altimeter set up in the nose cone I only added about 8oz of weight. It flew strait as an arrow on a Loki J-396. The OR sims I ran showed it stable at 4oz, But the prefect felt we should go with more weight. I made the weight removable so I can add or subtract depending on the motor. The Magg will ride a G-80 to 600 feet with no nose weight.

TA
 
I used my Magg for my L1 flight. Didn't add any nose weight, used an AT H123, and it flew very straight. But for a Level 2 flight, I'm sure I'd add nose weight.

minie_magg_L1_12_edit.jpg

minie_magg_L1_14.jpg
 
Beautiful paint job! I ordered some decals from stickershock for mine.

I love the way the fins attach to this rocket.

IMG_0523.jpg
 
thobin said:
I made the weight removable so I can add or subtract depending on the motor. The Magg will ride a G-80 to 600 feet with no nose weight.

TA
Click to expand...

How did you make the weight removable? I've just been epoxying shot into the nose cone.
 
beerandrockets said:
Beautiful paint job! I ordered some decals from stickershock for mine.

I love the way the fins attach to this rocket.
Click to expand...

It's definitely a unique mounting method. I had to round the corners on the keepers (for lack of a better term) to get them through the slots.

minie_magg_fin2.jpg

minie_magg_fin3.jpg
 
Speaking of rounding, I've seen lots of people commenting about rounding or beveling the leading edges of their fins. Is this just a performance choice? I'm not going for high altitude flights (I like low and slow), so is there another reason to do this?
 
beerandrockets said:
Speaking of rounding, I've seen lots of people commenting about rounding or beveling the leading edges of their fins. Is this just a performance choice? I'm not going for high altitude flights (I like low and slow), so is there another reason to do this?
Click to expand...

I think it can make a difference on high performance rockets and/or thicker fins. I usually round mine just for looks, but not always.
 
beerandrockets said:
Speaking of rounding, I've seen lots of people commenting about rounding or beveling the leading edges of their fins. Is this just a performance choice? I'm not going for high altitude flights (I like low and slow), so is there another reason to do this?
Click to expand...

On an L2 attempt it will probably make a difference, meaning you will probably get more speed and gain higher altitude. I did a quick layout of a minimag from what I saw visually, and added a pound of weight in the nose (that gets you to almost 1 ca. stability). The simmed altitude with a CTI J285 from rounded fins was 5% higher than with square. It was 6% higher with airfoiled fins. In all three cases you were below mach 0.8 meaning you probably weren't going to go transonic. I think it will be a lot of fun with 5 grain motors, although I would be suspicious of the fin mounting system with anything that pushes it above mach 0.85. The flutter is going to put a lot of stress on your airframe without the fins being mounted to the motor tube as well.
 
EeebeeE said:
On an L2 attempt it will probably make a difference, meaning you will probably get more speed and gain higher altitude. I did a quick layout of a minimag from what I saw visually, and added a pound of weight in the nose (that gets you to almost 1 ca. stability). The simmed altitude with a CTI J285 from rounded fins was 5% higher than with square. It was 6% higher with airfoiled fins. In all three cases you were below mach 0.8 meaning you probably weren't going to go transonic. I think it will be a lot of fun with 5 grain motors, although I would be suspicious of the fin mounting system with anything that pushes it above mach 0.85. The flutter is going to put a lot of stress on your airframe without the fins being mounted to the motor tube as well.
Click to expand...

I'd want to keep the velocity as low as possible. They're big, 1/8" fins. Prone to flutter.
 
Last weekend I sucessfully flew my Minni Mag on an Aerotech J420 to 3100' for my successful lvl 2 cert.

Here is my Failed lvl 2 cert attempt from 9 months ago.
[video=youtube_share;GTWA7e7DcfU]https://youtu.be/GTWA7e7DcfU[/video]
Fail was due to wrong delay and early chute deployment.

My fix was to add an altimiter for apogee deployment.
 
That is a mind-blowing camera setup on that launch pad! Love it!!!

If your worried about fin flutter, some tip to tip fiberglass would help. I have three rockets (Bruiser, Warlock, Doorknob) that use that type of fin keepers and glassed them all. Never had a fin issue and I've launched the Bruiser on "K" motors.
 
Last edited:
Thonawit said:
Last weekend I sucessfully flew my Minni Mag on an Aerotech J420 to 3100' for my successful lvl 2 cert.

Here is my Failed lvl 2 cert attempt from 9 months ago.
Click to expand...

Ya gotta love a launch pad that uses turnbuckles! The slo-mo of the ignition sequence was very cool!
 
Nice flight!


That has got to be one if the coolest launchpads I have ever seen. Any chance you have some pictures of the entire setup?
 
And here's the final version, painted and stickered. Hat tip to StickerShock for the awesome, custom Calvin and Hobbes decal job.

Calvin&HobbesRocket.jpg
 
qquake2k said:
I'd want to keep the velocity as low as possible. They're big, 1/8" fins. Prone to flutter.
Click to expand...

What he said. Wise advise. Not a near mach rocket. Keep low, slow, and simple, then go crazy. Good luck on your L2. (I don't like to call it an attempt).

Chris
 
I think I may be starting work on mine this week or next. How did you settle out on nose cone weight? (if you posted it couldn't find it)... and some of you mentioned fancy weight retention methods (adjustable), but my forum searches have found little on the subject. Some elaboration would be nice.

TIA
 
Nosecone with paint, decals, and weight came in at 785 grams. Of course, I forgot to weigh it at the start, so not exactly sure what the change was. :facepalm:
 
My 4" upscale of an Estes Fat boy can fly with little or no added nose weight with Barrowman 0.62 or Rocksim 0.90 calibers of stability. The secret is the base drag on short fat rockets adds to the stability without requiring adding weight. In Rocksim you add a weight less transition to the back of the rocket that begins with a front dia. of 0.010" ends 12" later with an aft dimension of 4.030" (OD of Rocket). This increases the calibers of stability to 1.35 Barrowman and 1.39 Rocksim.
When I built it I had added 1 lb. of nose weight to get it stable. I removed all of the added weight and it is still stable.
It is really cool on a CTI 38mm 2 grain H400.


3.9FatboyFOTF11.25.jpg
Ready for launch

Rocksim file.
View attachment Fatboy38.rkt
 
4kids49 said:
What he said. Wise advise. Not a near mach rocket. Keep low, slow, and simple, then go crazy. Good luck on your L2. (I don't like to call it an attempt).

Chris
Click to expand...

I dunno about that. Fred Gruis built and flew a beefed up Mini Magg on a Kosdon L1860... That was awesome... And he got it back again... and again... and again. Where the guy is now, I have no clue!
 
mrwalsh85 said:
I dunno about that. Fred Gruis built and flew a beefed up Mini Magg on a Kosdon L1860... That was awesome... And he got it back again... and again... and again. Where the guy is now, I have no clue!
Click to expand...

I believe it. I was just agreeing with qquake to keep it simple for cert. attempts. Some people do high flying, dual deploy, mach busting L2 certs. Whatever works. I just prefer to be conservative, get the certification, and then go for it.


Chris
 
Sailorbill said:
My 4" upscale of an Estes Fat boy can fly with little or no added nose weight with Barrowman 0.62 or Rocksim 0.90 calibers of stability. The secret is the base drag on short fat rockets adds to the stability without requiring adding weight. In Rocksim you add a weight less transition to the back of the rocket that begins with a front dia. of 0.010" ends 12" later with an aft dimension of 4.030" (OD of Rocket). This increases the calibers of stability to 1.35 Barrowman and 1.39 Rocksim.
When I built it I had added 1 lb. of nose weight to get it stable. I removed all of the added weight and it is still stable.
It is really cool on a CTI 38mm 2 grain H400.
Click to expand...

I find this a very useful idea. Is there a rule of thumb as to when to apply it in terms of, say, length to diameter ratios?
 
4kids49 said:
I believe it. I was just agreeing with qquake to keep it simple for cert. attempts. Some people do high flying, dual deploy, mach busting L2 certs. Whatever works. I just prefer to be conservative, get the certification, and then go for it.


Chris
Click to expand...

Why? Whatta they going to do if you fail? Make you fly another rocket? :grin:
 

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