Bought a Magnum

Hi.

I just bought a LOC Magnum. A couple friends and I are going to build it during our Christmas vacation. I am going to modify it to carry a homemade timer in the tail. At the next launch, I plan to launch it on a cluster of two H220T motors, then airstarting a White Lightning I motor .

Doug,
One thing you may want to keep in mind is that if one of your H220's fails to light, you'll get asymmetrical thrust which could lead to some very bad things. You might be wiser to light your central "I" first and then airstart your 2 "H's".

I concur dude. Switch em and airstart the Hs.

Also, have you rocksimed it? Just doing some fuzzy math, you would have about an equivalent "J". For some reason I'm thinking that is too small for the size of the Magnum...

Very good rocket, BTW... I've been wanting to add one to my hangar for a long time. Have fun building it and make sure you take lots of pictures.

I though about this for a while, and decided that I wanted to go with the two H220's first, then the central I. Rocksim predicts that two H220's airstarting a I211 will bring it between 2500 - 3000 ft. Plenty high enough for the local field I use.

With all of my clustered composite flights, I never had a misfire. I am sure that the rocket would be fairly stable with one H220 going, but my main concern is the altitude. The two H220's will burn out around 200 - 300 ft ... a half second before the main ignites. What would one H220 do....

Also, if one H220 ignites slightly before another, I want it to happen while it is still guided by a rail... not in the air, where it may vector off into an area where I cannot get to the rocket.

Risky bussiness, I know... but I just love the challege .

The Doug.

LOL and challenge shall you have young Pada-Won.

You will understand the caution when you find out where we are coming from. Mark has a Viper with 3 24mm motor tubes. I guess he has launched it at least 6 times and has yet to light all 3. Even with thermolite. But... Just because he is a loser doesn't mean you have to be. Good luck bro...

I too have a Magnum that I plan on clustering eventually. I can't see two 29mm motors lifting my Magnum very far, other than two I200's. I would suggest using the two 29mm's as accelerators, so you can use a smaller central motor, and get it up to speed with two fast motors in the outboards. I plan on doing this with a Pro38 3 grain I205 and two H238T's all lit on the pad. The other cluster that I want to do is a J420R and two H165R's or H210R's in the outbaords. A big red flame trailing a big blue Magnum I would also suggest stretching the payload bay to incorporate dual deployment. The Magnum was fun to build and is a very rugged rocket. K670GG at NYPower next year!!

make it low and slow

hehehehehe

Originally posted by PGerringer
I concur dude. Switch em and airstart the Hs.

Also, have you rocksimed it? Just doing some fuzzy math, you would have about an equivalent "J". For some reason I'm thinking that is too small for the size of the Magnum...

Click to expand...

A Magnum will do just fine on a J, provided its not a J90 or J180. I've seen Magnums fly on just one I357, or on three G125s. It might not be the highest flight of the day, but 320 N-sec will get a stock Magnum off the ground.

I will definitely agree about airstarting the Hs. One H220 does have enough kick to get a Magnum off the rod/rail, but obviously not in a straight line, which could be disastrous. You'll be MUCH better off having one of the Hs not light when the rocket is already travelling at speed; it won't deviate from the intended path nearly as far, and if it does, it'll be well away from spectators. I speak from the personal experience of having an NCR Archer [back when they sold them with a 29mm and two 24mm outboard motor mount] turn into a lawn dart when one of the E30s didn't light [I had intended for the E30s to airstart an H120]. It went away from the crowd fortunately, but if it went the other way...

If you still want the desired effect [getting a smoke trail to start in mid-air, always a cool effect], try an I300 airstarting two H180s.

This weekend at Whitakers a guy had a Blue Magnum with a central J and outter Hs. He did the central launch with the Hs as a 2 second airstart beautifully. I gotta get one of these...

That was me! I did an airstart on my Magnum with a central full J (Experimental motor) and 2 sideboard H180's. They lit a bit late, but still gave plenty of extra boost. Also, for the record, I have launched my Magnum (10 1/2 pounds dry) on an I284, and it only went 800 feet.

I would highly recommend that you NOT light the two sideboards on the ground unless you also light the central motor on the ground. Two very bad things can happen (and probably will, given how little power you will have on the boost). First, one of the motors can light later than the other, or not at all. The former will send your rocket off at an angle, far away from you, and the central motor will only send it farther. The latter will be very bad for all involved, because your rocket will probably arc over severely, hit the ground under boost, and then light the central motor. I would be reluctant to allow this configuration if I were RSO.

Second, the timing is critical. 2 H242's are going to burn for a very short time, and they will be carrying the entire weight of the unlit central motor as well. You'll get signficantly less boost out of those motors than you expect, because of the extra weight they are carrying. So, the timing of lighting the central motor, during the boost phase, will be critical to probably within a half a second. Your rocket will go a few hundred feet, and in just 1 or 2 seconds, start to arc. Your central motor will light at some point during that arc, and you'll be chasing your rocket as it goes toward the horizon.

Just my two cents.

David

Originally posted by DCox
That was me!

Click to expand...

Dang! I know names, I know faces I just cant put the faces with the names. Sorry about that...

So, how many flights did you have that day?

I had 4 flights. The flights as I recall them were:

1) My Magnum on a full J500 blue (3-grain 54mm), with 2 airstart H180's: 3500'
2) Alan's Flying Butress - hung in the power lines
3) My Baraccuda on a 3-grain 29mm "brilliant red" H100: 1900'
4) My Mirage on a 4-grain 38mm combo - 3 blue grains; 1 red grain I150: 2600'
5) Jim Livingston's Viper on an M: ~4500'
6) My Mirage again on a 3-grain 38mm Manganese Dioxide I120 - pale orange flame: 1900'
7) Phil's El Diablo on a 5-grain 54mm K: 1500'

I have lift-off photos of most of these, including shots of the blue, red, and orange flame colors. What is the best way to post photos? I tried attaching one, but it was too big.

-- David

If I ever get around to building the kit, I plan on going with
a single 54mm for at least the first flight. It would be cool
to jam in a couple of small air start 29s just for the smoke trail.
If I can ever figure out how to reduce my picture size , I have
some great shots to share.
Dr Don

Yup... lighting the Hs on the ground isn't easy, and you may end up with asymmetrical thrust... Here is a clip of this happening with a LOC Bruiser EXP(wasn't mine )... the plan was to take off on 2x I300Ts and airstart a J135W, but one I300 lit first and took the rocket off the pad into the crowd and towards a cameraman covering the event for Battle Bots (see https://www.rockitz.com). Then the second I300T lit in the air and kept the rocket going. Thankfully, the J135 did *not* ignite and the rocket landed about 10 feet short of the flightline.

Doug,
How old are you? Would you be interested in joining GYRO, the Global Organazation of Rocketry. We have a discussion group, and a couple of us are resurecting it from the dead. Email - [email protected] if interested

I am going to be 24 in April, so I think I am to old to be a member. However, l am willing to help out time permitting.

Doug, I hope Davey's video of the Bruiser changes your mind about launching the Hs and airstarting the I. That is a great video to use to show what not to do.

Well, when I fly the magnum, I would probabily go with a I300 staging to two H180's... thats assuming we will be able to use AP motors again

Gooooood choice, Doug...

Great Video!
I have seen that happen once too often!
That kit was around $200 on a 2001 LOC/Precision catalog price sheet that came in my Magnum kit. OUCH!!!
Dr Don

Yup... it was the guy's first flight with the kit too . I kinda feel bad for him... then again, that was a bad call on the motor planning and he shoulda known better...

David

Did it trash the rocket?

As far as I know, yes. Take a look at it...

Its hard to see through the smoke and flames coming from the cavern it left...