LOC Magnum

[Rob Campbell]

I am considering a LOC Magnum to have ready for this fall. I am leaning toward the "classic" version with a central 54mm motor and outboard 29mm motors. The latest version comes with motor tubes for up to six outboard motors, vs. two. It appears I will need to order a separate e-bay as this version doesn't appear to include one. Any thoughts and recommendations on which way to proceed?

 

[Donnager]

I am considering a LOC Magnum to have ready for this fall. I am leaning toward the "classic" version with a central 54mm motor and outboard 29mm motors. The latest version comes with motor tubes for up to six outboard motors, vs. two. It appears I will need to order a separate e-bay as this version doesn't appear to include one. Any thoughts and recommendations on which way to proceed?

Get it.

The Airstart bay with a couple of Altus Metrum EZtimers for mine was 100% custom, located between the middle and front centering rings. Get the standard E-bay for the regular dual deploy, and you can put your regular electronics there.

I've done a 38mm launch with an air start of some H-119's. The rocket does fine. Do you have any specific concerns?

 

[Rob Campbell]

Get it.

The Airstart bay with a couple of Altus Metrum EZtimers for mine was 100% custom, located between the middle and front centering rings. Get the standard E-bay for the regular dual deploy, and you can put your regular electronics there.

I've done a 38mm launch with an air start of some H-119's. The rocket does fine. Do you have any specific concerns?

No. I just looking for advice on flight computers for air starts and what experiences others have.

 

[tsmith1315]

I am considering a LOC Magnum to have ready for this fall. I am leaning toward the "classic" version with a central 54mm motor and outboard 29mm motors. The latest version comes with motor tubes for up to six outboard motors, vs. two. It appears I will need to order a separate e-bay as this version doesn't appear to include one. Any thoughts and recommendations on which way to proceed?

I'm looking forward to seeing that, Rob!

 

[Rob Campbell]

I'm looking forward to seeing that, Rob!

GRITS awaits.

 

[Hobie1dog]

JUST DO IT

 

[Donnager]

No. I just looking for advice on flight computers for air starts and what experiences others have.

Unless you get something like a Raven or Multitronix (which I don't know if they are in production--I haven't been able to buy much over the last year other than the cheap stuff, due to availability), you will probably look at EasyTimers (AltusMetrum) and Missileworks RRC3's. The only suggestion I'd have with Easytimers is to read the instructions in detail. Then, do a search for EasyTimer in the instruction PDF. There you should find out how to set up air starts, and it won't be in the EasyTimer section of the Altus Metrum document.

If you use these, I have two suggestions. 1) Verify you have the most current firmware. Flash/upgrade as needed to bring your device current. Some sat in inventory long enough that the software/firmware was changed in the interim. and 2) not verified, but I was unsuccessful at using A and B channel at the exact same time with the same start conditions. I am not sure if this worked poorly because the EasyTimer is not really designed to fire both channels at the exact same time, a battery issue, or if it was a problem that upgrades would have addressed. Normally you can fire a handful of e-matches with a near dead 9V battery, so I'd tend to lean toward some kind of constraint in the device.

 

[waltr]

I have used the Eggtimer Quantum and now a Proton for 2-stage air start.
Both use a WiFi interface to setup, Arm and download flight data. This is really nice.
They also have a master switch that disables outputs until armed.

The Quantum has only two channel outputs and uses a Timer based on launch detect.
The Proton has an Accelerometer so Air start timing can start a motor Burn-out.

It would be worth your time to download the Quantum & Proton doc and read the Air Start sections. Cris has some good info in there that can be applied regardless of which board make you use.

 

[Tim51]

No. I just looking for advice on flight computers for air starts and what experiences others have.

I don't have a Magnum but I use a Missileworks RRC3 for airstart duties backed up with an RRC2+ on my 5.5" airstart bird, which was scratchbuilt with primarily Loc materials. To date I've done 5 airstarts without a hitch. IMHO the key issues are:
(i) correctly studying, understanding and using the MW Mdacs programming software with your laptop to set up the parameters. The RRC3 does not have a tiltometer but it allows you to determine a minimum safe altitude in the flight at which the airstart circuit arms
(ii) Determining an appropriate delay before outboard ignition, bearing in mind you don't want the rocket arcing over under auxiliary thrust, and few motors are 'instant on', most take a little time to come up to pressure. In my experience, a delay of 2.2s works for a variety of flavours (I tend to use K motor cores with H or I outboards). Allowing the ignition sequence begin in the very last moments of the core burn still ensures a pleasing time gap in the sequence.
(iii) good breakpoints and appropriate shearpinning.
(iv) Sim, sim sim in detail. Ground test groundtest, ground test
(v) use a checklist on every flight.