Loki M-1378 for L3 Cert Flight

[Gary Mac]

Any reasons why I shouldn't be looking at using a Loki M-1378 for my L3 cert flight? I understand it's a relatively new motor with a very high L/D ratio, so I'd enjoy hearing other's feedback on it. I like that's it's a relatively small impulse/high thrust design and also, after the L3 cert is in the bag, it would leave me with a nice motor case for future use in high-speed 54mm min-diameter rockets, rather than a shorter/fatter motor casing that some of the more "traditional" small M's in 76mm (such as the M1297) would.

From the OpenRocket sims, it accomplishes what I'm looking for ballistically, assuming one can handle packaging the ≈4' of case length.

https://lokiresearch.com/secure/storeDetail.asp?id=625201611015134

 

[dhbarr]

I've seen a few fly, looked great.

 

[ericm541]

Looks like fun, the "largest 54 MM reload certified for hobby use, ever" makes me want one. The case for the M1297 has good options for L and M motors which is why it's preferred, it's also 4 grain so not really short. Loki case look like it cost a lot less than aerotech.

 

[ECayemberg]

I'm not advising you not to use one....just saying the following.

Having flown one, it's a bit of a finicky motor. Motor assembly is not difficult, but requires a bit more effort than most "standard" motors. Ignition is not impossible, but is difficult; Loki Red takes a good igniter to get it going, and the 1378 takes extra special care. I'm one to use igniters that are strong enough to light dirt...while mine lit, it did a mega chuff, hopped up the pad, slammed back down, before leaving the pad...nerve wracking events, especially since I was using fly away rail guides, a decent sized standoff, and the nozzle is exposed as the lowest part of the rocket. Lastly, the nozzle itself is a special piece...a pretty sweet hybrid of machined garolite and graphite! Scott has been doing some tweaking on the nozzles; my motor had issues due to the nozzle being not-exactly-right; though I believe he's got it figured out now.

So, I guess what I'm saying is: Buy and Fly an M1378; they're neat motors! But, because they are a bit more temperamental than shorter Length : Diameter ratio motors, I'd personally advise to use another motor for your L3 shot. That said, if you were "my" candidate, there's no way I'd stop you from using the 1378 in your attempt!!!

 

[pondman]

I'm not advising you not to use one....just saying the following.

Having flown one, it's a bit of a finicky motor. Motor assembly is not difficult, but requires a bit more effort than most "standard" motors. Ignition is not impossible, but is difficult; Loki Red takes a good igniter to get it going, and the 1378 takes extra special care. I'm one to use igniters that are strong enough to light dirt...while mine lit, it did a mega chuff, hopped up the pad, slammed back down, before leaving the pad...nerve wracking events, especially since I was using fly away rail guides, a decent sized standoff, and the nozzle is exposed as the lowest part of the rocket. Lastly, the nozzle itself is a special piece...a pretty sweet hybrid of machined garolite and graphite! Scott has been doing some tweaking on the nozzles; my motor had issues due to the nozzle being not-exactly-right; though I believe he's got it figured out now.

So, I guess what I'm saying is: Buy and Fly an M1378; they're neat motors! But, because they are a bit more temperamental than shorter Length : Diameter ratio motors, I'd personally advise to use another motor for your L3 shot. That said, if you were "my" candidate, there's no way I'd stop you from using the 1378 in your attempt!!!

Eric pretty much hit the nail on the head here. Because of the "uniqueness" of this motor, you may also want to look into borrowing a case rather than buying one.

 

[Gary Mac]

I'm not advising you not to use one....just saying the following.

Having flown one, it's a bit of a finicky motor. Motor assembly is not difficult, but requires a bit more effort than most "standard" motors. Ignition is not impossible, but is difficult; Loki Red takes a good igniter to get it going, and the 1378 takes extra special care. I'm one to use igniters that are strong enough to light dirt...while mine lit, it did a mega chuff, hopped up the pad, slammed back down, before leaving the pad...nerve wracking events, especially since I was using fly away rail guides, a decent sized standoff, and the nozzle is exposed as the lowest part of the rocket. Lastly, the nozzle itself is a special piece...a pretty sweet hybrid of machined garolite and graphite! Scott has been doing some tweaking on the nozzles; my motor had issues due to the nozzle being not-exactly-right; though I believe he's got it figured out now.

So, I guess what I'm saying is: Buy and Fly an M1378; they're neat motors! But, because they are a bit more temperamental than shorter Length : Diameter ratio motors, I'd personally advise to use another motor for your L3 shot. That said, if you were "my" candidate, there's no way I'd stop you from using the 1378 in your attempt!!!

Thanks for the reply Eric - that is exactly the kind of tips/experience I was hoping someone would have. Do you mind me following up and asking what your igniter setup was on your "chuff" flight? If I ever get a chance to fly one, I'd like to avoid accidentally repeating that experience, even with an Aeropack tailcone to help protect the exposed nozzle.

For those who haven't seen it before, here is Scott's "how-to" video on how to glue/assemble the grains for this motor. He really does an excellent job on his how-to's.

 

[ECayemberg]

Thanks for the reply Eric - that is exactly the kind of tips/experience I was hoping someone would have. Do you mind me following up and asking what your igniter setup was on your "chuff" flight? If I ever get a chance to fly one, I'd like to avoid accidentally repeating that experience, even with an Aeropack tailcone to help protect the exposed nozzle.

You bet! Igniter was: 1/8" dowel, Wildman Big 'Un, 3 slivers of Blue Thunder (or equivalent) taped to the head. Not a lot of spare room between the igniter head and propellant cores. Slower, longer burning ignition boosters work better here.

There's two things working against users here: 1. Loki Red is just hard to ignite...almost inert! 2. The grain geometry lends to a very low startup k/n which means the motor when lit doesn't really want to stay lit until erosive flow kicks in and somewhat neutralizes the low initial k/n.

That said, this is a really awesome offering from Scott. I did a backflip or two when a 54mm M was certified! 38mm K's, 54mm M's, and 75mm N's make me giddy!

 

[heada]

To help ease starting this beast, can you coat the top of the top grain in a pyrogen to help mitigate a chuff? I'm thinking 1/2" to 1" of the core of the top grain. It should give direct flame propagation to the grain and is a slower burn than say a pyrodex pellet. Since you have to epoxy the grains into the liner anyway, I think adding some pyrogen at the some time should be an easy thing.