Next Project

[Elapid]

8.5" Mini Magg Upscale

i'll be using the acid neutralizer fiberglass tube, cut to 36.88" give or take a few mm.

i'll have to find an 8" x 20" ogive nosecone or make one custom...
should be a fun project. i'll most likely use a switchable MMT so i can use a variety of different motor sizes/configurations. fins are going to be made from honeycomb composite.

 

[GL-P]

Woohoo! What's the biggest motor you'll fly in it? Are you going to make your own switchable mmt?

They're easy and pretty simple. I've helped my dad in his rocket with one and I plan on doing one with a 54mm removable acme fincan.

 

[Neil]

Thatll be cool... What does Rsim say it will weigh?

 

[Elapid]

i made a switchable MMT for my super big bertha so i can use a single 29mm, or 2,3, or 4 24mm motors. i'll use a thrust ring for the forward stop and for positive retention most likely blind nuts and some nice countersunk bolts.

i haven't sim'd it yet.
i need to sand the ends of the tube, weigh it, then imput the data. i'll be using composite materials throughout the model, so i'll have to wait until the project is complete before i'll have any accurate simulation information.

i have the motor cases to fly it on 4x38mm (2x600Ns/2x720Ns) with a central 54mm up to 1706Ns

most likely fire the 54mm, then airstart one pair of 38s at a time...

of course, with the switch mount, i can make a variety of configurations to suit the condition of my wallet

 

[GL-P]

Sweet! That sounds like the same config my dad did in his latest rocket.

 

[Ryan S.]

take a look at Jerry Osullivan's nike Smoke adapter, it is a very good idea and it might contribute to yours.

 

[Elapid]

here's the simfile so far...
i stuck a 98mm in to see what it will do...

 

[Neil]

Where is the electronics bay?


You are putting railbuttons on this rocket, right?

Just making sure... all I see in the sim are 3/4" lugs...



And the 50" chute? whats that all about? I dont think you want it coming down at 34 FPS...

Edit: Oh, the chutes a skyangle... Do those come down slower than other ones? Still... 50" is a little small for an 8" rocket IMHO...

 

[Ryan S.]

here are some links, he does his adapters that fit 3 6000NS Ms the same way, just the configuration in the middle is different

https://www.mdrocketry.org/photos/esl72/Full/JKMVC_001S.JPG

the adapter

https://www.mdrocketry.org/photos/esl72/Full/JKMVC_013S.JPG

another this one with the rocket

https://www.mdrocketry.org/photos/esl72/Full/JKMVC_028S.JPG

installation

https://www.mdrocketry.org/photos/esl72/Full/JKMVC_029S.JPG

there ya go

 

[Justin Horne]

Originally posted by Neil
Where is the electronics bay?


You are putting railbuttons on this rocket, right?

Just making sure... all I see in the sim are 3/4" lugs...



And the 50" chute? whats that all about? I dont think you want it coming down at 34 FPS...

Edit: Oh, the chutes a skyangle... Do those come down slower than other ones? Still... 50" is a little small for an 8" rocket IMHO...

It's not that it comes down slower, it's that a 50 inch skyangle is really bigger than that. For my 5 or so pound jag, i've got a 36 inch skyangle in the mail...

 

[Elapid]

it's not set in stone.


i'll use a proper sized chute.
the electronics bay will be accessed via a hatch in the side of the rocket, most likely in the fincan area. we'll see where the room is when it's done.

 

[Neil]

Most likely in between the fins, going by the sim... There isnt any MMT to mount it to past the fins... Speaking of the motor mount, dont you think its a little short? I personally would make it a little longer... As long as that 98MM L motor that you simmed it on at least...

I had fun putting an O3000 in there... that motor is so long, it sticks out several inches past the nose tip!!!

 

[Elapid]

i bought a commercial Kwik Switch adapter for a 54mm -> 38mm and it measures 10" long, it appears to mot matter much how long the actual mmt is, as long as it keeps the motor aligned properly in the rocket and allows for adequate retention.

in other words; i think the MMT is just fine, considering it is just something i put in the sim to hold a motor. the ACTUAL mmt will most likely be made from something a bit larger to hold different combinations of motors.

i made the rocksim file solely to get an estimate of the rocket's performance. i'll make a file that reflects the actual rocket when the rocket's done and painted.

 

[daveyfire]

Sounds good, Elapid! The way I like to do interchangeable mounts is to put in a tube with the ID large enough to house any motor combination that will fit... in something like this, I'd put in a 7.5" tube. That gives you options of 1x54, 7x54, 1x75mm + 6x 38mm, 1x98mm + 6 38mm, 4x75mm, and a whole bunch of others. I would think a short piece of glassed (or unglassed and well-supported) QuikTube would be up to the job, and cheap too

I've found that you really only need to keep the MMT as long as the fin roots, just so that you can have something to do TTW construction with. Other than that, you really don't need all that extra tube, except as a stuffer tube... which, in HPR, usually isn't needed. Exception: you're flying Hypertek and you want to support the upper end of the tank and bell, in case you have a "less than optimal" launch

May I also suggest using accelerometer-based avionics and locating them in the nose cone. This will not only help out with the (massive!) amount of noseweight you will need, it also frees up space in the bottom of the rocket for more motors!

Good luck with this project, it's gonna be awesome. When do you first expect to put it up?

 

[Elapid]

for all kinds of stuff.
possibly in September...
depends on how much time i'm able to put in.

right now i'm looking at finishing the ends of the tube, after cutting it with my reciprocating saw, with a 3x5" sanding block and thinking there must be a better way! so there it sits awaiting better technology, i.e. belt sander.

looks lik e a trip to the hardware store is in order!


thanks for the info!
i'll post updates as i progress through the build process.