Should I buy a LOC Precision VII kit or just the parts to eliminate the MMAS motor mount tube to cut down on weight?

[ridnharley]

My plan is to fly the VII on 54mm CTI reloadable motors.
If I buy the parts needed from LOC, I could eliminate the MMAS weight from the rocket.
The parts I would need to order different from the kit would be a 54mm motor tube and 3 centering rings.
I would have to cut out my own fins from 3/8" baltic birch.
I believe by doing this I would have a lighter rocket.
Any thoughts or ideas on this?

Thanks in advance, Al

 

[jmasterj]

I would just contact LOC and see if they'll make you a modified kit.

 

[Hobie1dog]

contact LOC first, I think 3/8" fins are going to be overkill. 1/4" should be fine IMO.

 

[Rschub]

You could get the centering rings, and just cut off the small section of fin that would have fit in the locking slots of the original bulkheads and assemble it the normal way. No need for all new fins.

 

[jmasterj]

You could get the centering rings, and just cut off the small section of fin that would have fit in the locking slots of the original bulkheads and assemble it the normal way. No need for all new fins.

The tabs won't reach a 54mm mount since they're designed to be used with the 5.5" MMAS mother tube.

 

[Rschub]

Do they need to go all the way to the motor tube? Genuinely curious, seeing as there are surface mounted fins on minimum diameter rockets.

 

[ThirstyBarbarian]

LOC is very good about custom kits. I’m sure if you just asked them for a kit made with a 54mm tube, no MMAS, they would make it. And I think a 54mm Mount is definitely a better way to go.

 

[ThirstyBarbarian]

Do they need to go all the way to the motor tube? Genuinely curious, seeing as there are surface mounted fins on minimum diameter rockets.

They should be glued to the motor mount tube, for sure. That tail cone is hard to get a good glue bond to. The plastic is really resistant to glue and paint.

And you should not need to make new fins or do anything other than just ask them for a V2 with a 54mm mount. They will make the correct fins for you. At least they used to do that kind of thing, and I bet they still do.

 

[DAllen]

Just buy the kit. On a rocket that size the weight difference will be negligible.

 

[Rschub]

That tail cone is hard to get a good glue bond to

Lol, go home, you're drunk. We are talking about the 7.6" LOC VII. [7] for us non-Romans. There is no tail cone.

And I maintain that there is no need to go all the way to the motor tube. You could also cut notches in the new bulkheads if you wanted to preserve the fin-lok feature.

 

[techrat]

VII

Probably misread as V-2 as in the German V2 rocket... which does have a tail cone.

 

[jmasterj]

Most of the strength of TTW fins is in their connection to the motor tube, so I think you're on you're own here, @Rschub.

 

[ThirstyBarbarian]

Lol, go home, you're drunk. We are talking about the 7.6" LOC VII. [7] for us non-Romans. There is no tail cone.

And I maintain that there is no need to go all the way to the motor tube. You could also cut notches in the new bulkheads if you wanted to preserve the fin-lok feature.

Lol! Ok, I thought for some reason we were talking about a V-2, and was trying not to correct the weird VII spelling of V-2. I’m losing it.

As long as the fins are locked somehow on the inside, maybe notched and glued to the centering rings, then it would probably be OK. But I would probably prefer to have the tabs go to the motor mount tube.

If he already has the kit with the MMAS, and would prefer a 54mm mount, then maybe working with the existing fins and just ordering certain parts to replace the MMAS might make sense. If he does NOT already have the kit, then I’d still suggest just calling up LOC and asking for a kit made with a 54mm tube and all the appropriate parts.

Although, now that I know what kit we are talking about, personally, the LOC VII is the one kit I might actually like made with the MMAS. Usually I’d just prefer most rockets without that, but the LOC VII is a big rocket with a lot of potential configurations, and it might be nice to have the versatility.

 

[Rschub]

I am not saying it would be ideal, just that it would probably work, and be the lightest. I personally would use the MMAS system for the motor flexibility. The parts can't weigh too much more than a lb. or 2

 

[David Schwantz]

I thought LOC allowed ever MMT system you wanted??

 

[cbrarick]

I'm confused.
You're buying a standard kit for J-K-L motors, something that is not minimum diameter but is 7.5 inches in diameter so it's very draggy
it weighs 17 pounds.
You're worried about a few ounces
Am I missing something?

 

[David Schwantz]

Motor Mount: 5.5" MMAS includes 54MM Adaptor

 

[ridnharley]

contact LOC first, I think 3/8" fins are going to be overkill. 1/4" should be fine IMO.

The airframe comes with 3/8" slots for the fins.

 

[Hobie1dog]

The airframe comes with 3/8" slots for the fins.

I didn't know that, sorry

 

[loopy]

Honestly, I'd buy the kit and build it as is and just use adapters. Or talk to LOC and see if they could make a custom kit with the correct fin tabs/CRs/motor tube for what you want to do. But this is a very large rocket with a huge amount of drag. I was considering ordering one of these in the past with a 75mm motor mount for my L3 cert. Make sure you're building this to take motors that will give it a safe flight.

 

[ridnharley]

Honestly, I'd buy the kit and build it as is and just use adapters. Or talk to LOC and see if they could make a custom kit with the correct fin tabs/CRs/motor tube for what you want to do. But this is a very large rocket with a huge amount of drag. I was considering ordering one of these in the past with a 75mm motor mount for my L3 cert. Make sure you're building this to take motors that will give it a safe flight.

Rocksim gave me 13-54mm Aerotech motors to fly that are safe.
I'm still investigating but so far things are looking good.

 

[loopy]

Rocksim gave me 13-54mm Aerotech motors to fly that are safe.
I'm still investigating but so far things are looking good.

Just curious - why would you limit yourself to 54mm? You can always adapt down...

 

[Rschub]

For various reasons I wish I had the option to put 54mm motors in my 38MM fleet (Is 2 a fleet?)

 

[ridnharley]

No need to adapt down with a 7.5" rocket.
I use my 5.5" rocket to fly 38mm.

 

[ridnharley]

After pricing up all the parts needed vs. buying a kit and adding the parts needed, it is cheaper to buy the kit and add the cost of the 54mm motor mount tube, 3 centering rings and the 3/8" baltic birch plywood for the fins.
Looks like that will be the way to go.

 

[ThirstyBarbarian]

When you say, “it is cheaper to buy the kit and add the cost of the 54mm motor mount tube, 3 centering rings and the 3/8" baltic birch plywood for the fins,” I guess I’m still not exactly sure what you mean.

Do you mean buy the standard kit, which includes the MMAS, the fins with the shorter tabs, and the parts for the MMAS 54mm motor mount adapter, and then also pay extra for a 54mm motor mount tube, centering rings, and 3/8” Baltic birch fins? And when you build it, you’ll have the parts for the MMAS, the original fins, and the MMAS 54mm motor mount adapter left over?

Or do you mean pay extra to order the kit produced with the 54mm motor mount tube, centering rings, and fins that you want? And you’ll just receive what you need, with no leftover parts?

It sounds like you are describing the first option. But I can’t imagine that’s cheaper than asking for a 54mm version custom kit and not having the leftover parts. Do they not do that anymore? Did you ask? It’s none of my business really, but I’m just curious if something has changed, because I’ve ordered custom kits before from them, and so have some of my friends, and it’s never been a problem. The guy I worked with was named Jay.