Minnie magg ejection question

[SRBell]

Just getting ready to fire up a LOC Minnie Magg. Being I'm pre level 1 I'll have to use a G76-4, won't go very hight...maybe 500' at best. Beyond getting a 29-38mm adapter, will I need to supplement the ejection charge that comes with the Aerotech motor? It's a pretty cavernous tube.

[terryg]

Yes, you will need more black powder. You can leave the red cap off and use masking tape to extend the well to allow more capacity. Use an ejection volume calculator to get an idea of the amount needed (the amount that comes with a 38mm reload would be a good starting point).

[qquake2k]

I hope you built your Magg lighter than mine. Mine weighs 62oz and won't fly on a G. It needs at least an H.

[SRBell]

I hope you built your Magg lighter than mine. Mine weighs 62oz and won't fly on a G. It needs at least an H.

I looked at the LOC "instruction sheet" for the rocket weight, specked at 40oz! Weighed mine and it's 51oz. That's a little disappointing. I build pretty light in general, a habit from building RC jets. I used a little hysol on the fins tabs, 1/2 oz fibreglass cloth on the fin's surface with 1/4 fillets made with resin and micro balloons, that's not overbuilding! But then I looked at the Rocksim simulation... Mass is at 61oz gave an altitude of 445' and 51oz pushed up to 595'. Do you think it will fly on a G76 at 51oz? I've heard from others on this forum that Rocksim can be off a bit.

[qquake2k]

I looked at the LOC "instruction sheet" for the rocket weight, specked at 40oz! Weighed mine and it's 51oz. That's a little disappointing. I build pretty light in general, a habit from building RC jets. I used a little hysol on the fins tabs, 1/2 oz fibreglass cloth on the fin's surface with 1/4 fillets made with resin and micro balloons, that's not overbuilding! But then I looked at the Rocksim simulation... Mass is at 61oz gave an altitude of 445' and 51oz pushed up to 595'. Do you think it will fly on a G76 at 51oz? I've heard from others on this forum that Rocksim can be off a bit.

Does your 51oz include recovery harness and parachute? According to Thrustcurve, at 51oz a G76 will get you to 467 ft.

[chadrog]

I don't think it would be safe to fly it on a G76. The thrust to weight ratio is barely marginal, and that's before concidering how drag-gy the Mini Mag is. Why don't you just fly it for level one certification? It's a great rocket for that. Or have you not hit the golden age yet?

[chuck5395]

How does the Minnie Magg sim out on a 38mm G61W or G67R. I use these in my Binder Design Thug rocket and they perform great.

[SRBell]

It's 51oz, everything included except for the 29-38mm motor adapter (on order), motor case and reload. As for the reason to launch on a G, I'm well over the legal age lol but live a fair distance from a club to certify. My son and myself will be heading that way later this summer. We were just looking for something to fly legal for the time being. I guess a G80 or G104 would be a better choice, just we've got about 20 G76's kicking around! BTW, thanks for the graph, it's cool when members here take the time to help out.

[chadrog]

It's 51oz, everything included except for the 29-38mm motor adapter (on order), motor case and reload. As for the reason to launch on a G, I'm well over the legal age lol but live a fair distance from a club to certify. My son and myself will be heading that way later this summer. We were just looking for something to fly legal for the time being. I guess a G80 or G104 would be a better choice, just we've got about 20 G76's kicking around! BTW, thanks for the graph, it's cool when members here take the time to help out.

Man! Wish I had that many G76's layin' around! It's one of my favorite motors. The G80 would be your only other option, I do believe the G104 is classified as high power.

Afterthought edit - If I had all those reloads, I'd have put a cluster in the magg, drooling - edit off

[SRBell]

Man! Wish I had that many G76's layin' around! It's one of my favorite motors. The G80 would be your only other option, I do believe the G104 is classified as high power.

Afterthought edit - If I had all those reloads, I'd have put a cluster in the magg, drooling - edit off

Funny you would mention the cluster. I saw a Minie Magg build with a 6 29mm cluster on the perimeter and a single 54 centre! The 6 29's were air start. That's a lot of punch for a short stubby rocket.

[MarkH]

Of any of the 29 mm AT G motors, I think the G76G is your best bet. It has about 35 pounds peak intial thrust compared to ~ 20 pounds for the the G80T and 27 for the G104T. The G80 has more total impulse (138 Ns) and the G104T less (90Ns). G76 total impulse is 118N-s. CHeck out the thrust charts in the Aerotech catalog for comparisons.

Based on the initial thrust/weight ratio ( around 11 to 12:1) being above the 5:1 rule of thumb, you should be good, just make sure it is a G76-4.

I have flown a 3lb rocket with the G76 off a 6 ft rail and it did just fine by the way.

[qquake2k]

Are you launching it off a rail or rod? How long is it? According to Thrustcurve, the velocity off an 8ft guide would be 62ft/sec with the G76, but only 52ft/sec with the G80. Things will change a lot, though, if you don't have an 8ft rail or rod.

[SRBell]

Are you launching it off a rail or rod? How long is it? According to Thrustcurve, the velocity off an 8ft guide would be 62ft/sec with the G76, but only 52ft/sec with the G80. Things will change a lot, though, if you don't have an 8ft rail or rod.

Nothing at 8'. We started with a 5' 1/4" rod, but after a few launches of my son's Madcow Bomarc we decided rod whip was a problem. Now we're using a once piece 6' rail from Giant Leap Rocketry. Way less friction and it doesn't rust lol.

[qquake2k]

Nothing at 8'. We started with a 5' 1/4" rod, but after a few launches of my son's Madcow Bomarc we decided rod whip was a problem. Now we're using a once piece 6' rail from Giant Leap Rocketry. Way less friction and it doesn't rust lol.

Yeah, I would definitely use a rail for a Minie Magg. If you shorten the rail length to 6ft in Thrustcurve, it gives 53ft/sec off the rail. Still doable. I would launch it on a very calm day, if it were me.

[tsai]

It's 51oz, everything included except for the 29-38mm motor adapter (on order), motor case and reload. As for the reason to launch on a G, I'm well over the legal age lol but live a fair distance from a club to certify. My son and myself will be heading that way later this summer. We were just looking for something to fly legal for the time being. I guess a G80 or G104 would be a better choice, just we've got about 20 G76's kicking around! BTW, thanks for the graph, it's cool when members here take the time to help out.

Make sure to weigh it with the adapter and motor in place as well. You're awful close to the 1500g limit for Class 1 rockets.

[accooper]

What you can do for the ejection charge is just cut the very top of the red cap off. This will leave a little longer container for the black powder. Then tape the top and around where the red cap meets the casing.

Hard to explain. easy to do.

Andrew

[Rocketjunkie]

A Mini-Magg should come with a lug for a 1/2" rod. I never had any problems when launching off a 1/2" rod.

[bjphoenix]

This one is 4" diameter x 31" long, and weighs 32 oz. I built it from leftover LOC parts, with a 38mm motor mount. It flies OK with a G64, not very high but high enough. I don't think I would fly anything larger on a G64.

[admiral11harpoon]

Hi SR, Ive flown mine on a G76-4(first flight). Mine weighs 55oz and flew it off a 6ft. 1010 rail. Wind was around 5mph. Went around 500 ft(very cool flight,jumped of the pad then accelerated slowly up),I would not fly it on much less than this motor.A G64-4 might be ok with no wind. buy the way I used the stock ejection charge. My nosecone was loose enough that i had to use a little masking tape on shoulder. Make sure it almost falls out when you turn rocket over. Gary

[gary7]

Any of you put any weight in your Minie Magg? My sims look alot better and show a more stable rocket with 8 oz in the nose.

[qquake2k]

Any of you put any weight in your Minie Magg? My sims look alot better and show a more stable rocket with 8 oz in the nose.

I never have.

[SteveF]

I have a minnie mag ready to start on - have rail buttons for it. I have a cesaroni 38mm 4 grain case - that case is an inch or two longer than the motor mount tube. I know that isnt a problem but it got me thinking about the best way protect the chute & my GPS unit I have fitted mostly in the nose? nomex blanket around the end of the motor? fill it to above the top of the motor with dog barf and then nomex blanket? other ideas?

I also plan on using kevlar of some length and then the elastic provided? 1 or 2 body lengths worth of kevlar sound about right? and what strength kevlar?

[cmcain]

you can do what i did i have a 1/4"x20' sewn kevlar shock cord and kevlar chute protector in my minnie magg from giant leap rocketry general rule of thumb with a shock cord in hpr the longer the better and trash the elastic i wont even use it in my midpower rockets because i have seen one too many fail and on a big rocket i honestly feel that a few extra bucks is worth the added saftey. also my minnie magg weighs 58oz and i wont fly it on anything smaller than an h123, my favorite all around motor in it is and I357t-m its a perfect flight every time

[qquake2k]

I use a 2ft length of 1/2" tubular Kevlar webbing (http://www.missileworks.com/index.php?main_page=product_info&cPath=4&products_id=28) in my Magg, and 25ft of 9/16" tubular nylon (http://www.rei.com/product/610111/bluewater-916-climb-spec-tubular-webbing). Mine weighs 62oz and I think that's too heavy for elastic. I use an 18"x18" Nomex blanket (http://topflightrecoveryllc.homestead.com/page3.html) to protect the chute and nylon webbing.

[SteveF]

thanks - guess I will just go with the kevlar and nomex blanket

[qquake2k]

Have you flown your Magg on a G yet? How did it do?

[SRBell]

Have you flown your Magg on a G yet? How did it do?

Waiting for the motor retention and adapter to come in. I don't have a 38mm case or 38mm reloads on hand. Should go up this week, I'll post some video.

[qquake2k]

Waiting for the motor retention and adapter to come in. I don't have a 38mm case or 38mm reloads on hand. Should go up this week, I'll post some video.

What kind of retention are you going with?

[SRBell]

What kind of retention are you going with?

I'm using a Aeropack retainer with the matching adapter (38-29mm). Using these on all our current projects, the Minni Magg, Hyperloc 1600 and a Madcow HoJo. Much better than the Aerotech motor hooks used on our first two rockets lol.

[qquake2k]

I'm using a Aeropack retainer with the matching adapter (38-29mm). Using these on all our current projects, the Minni Magg, Hyperloc 1600 and a Madcow HoJo. Much better than the Aerotech motor hooks used on our first two rockets lol.

I haven't tried Aeropacks, just because I'm so cheap. I've used homemade retention clips on all my MP and HP rockets, and haven't had any problems.