Formula 75 build thread

So I got everything I need. Unfortunately I don't have any motor mount tubes (for some reason they were omitted) so I ordered a cheap paper 35mm tube to cover for it. I can't start until I get that.

Here I have the kit, parachutes (30"), chute protector, kevlar cord, Loki 38/240 and 480 hardware, 2 I405 reloads, 2 H144 reloads, and 2 H160 reloads. I also have a 38mm aeropack retainer.

I have never seen a build thread include the reloads in the proverbial un-boxing...you are definitely enthusiastic about this. If Rocketry Warehouse left it out by mistake and you paid for it, then you should ask them to send you the MMT on their dime.

Good luck on the build.

I emailed and called them, but the phone number was only answered by a machine, and nobody answered any email thus far. Perhaps something's up.

taiwanluthiers said:

I emailed and called them, but the phone number was only answered by a machine, and nobody answered any email thus far. Perhaps something's up.

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Seem to still be digging out of the black friday backlog.....I contacted them about an issue....took a few days/week but he eventually got to me and made me happy.

I would try ordering the missing part & putting a note in with order explaining how you tried to contact them, just like you did here.

That should work. May be on vacation, etc. They are pretty good at fixing mistakes.....you just have to give them a chance.
How long ago did you try to contact, did you leave message or just hang up?

I'm sure they'll take care of you; they've been fantastic to work with.



Later!

--Coop

I contacted them yesterday. I left a message.

I just purchased a kit from RW and they omitted the fins. They responded to my email after a few days and just received missing fins. He was very apologetic. Be patient!

To be fair, the fiberglass tube is very sturdy. I bet I could shoot a 3" shell out of this if I wanted to... (incidentally some Chinese firework mortars are made of fiberglass, the same orange color as this one too. Difference is the Chinese mortar tubes are very roughly made, and often have sharp protrusions)

While waiting for the motor mount tube to come, I might as well do what I can now...

I am gluing the bulkplate to the coupler. I roughed up the inside of the coupler and then smeared it with black Rocketpoxy. The aluminum foil is there to prevent me from gluing the coupler to the table, not the best solution but it comes off even if I have to tear/scrape it off. I tried to suspend it but the rocketpoxy isn't thick enough to allow that... so I have to rest it against a flat surface. The coupler itself will be attached to the nosecone with nylon rivets, this is so I can use the nosecone as AV bay.

taiwanluthiers said:

I contacted them yesterday. I left a message.

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Gheeshhhh........ yesterday was Saturday....they're not even open, no wonder you didn't get a reply.

More reasonable time for an answer would be till Tues. Or call them Monday, when they are open.

They just replied that they will get the motor mount to me.

taiwanluthiers said:

While waiting for the motor mount tube to come, I might as well do what I can now...

I am gluing the bulkplate to the coupler. I roughed up the inside of the coupler and then smeared it with black Rocketpoxy. The aluminum foil is there to prevent me from gluing the coupler to the table, not the best solution but it comes off even if I have to tear/scrape it off. I tried to suspend it but the rocketpoxy isn't thick enough to allow that... so I have to rest it against a flat surface. The coupler itself will be attached to the nosecone with nylon rivets, this is so I can use the nosecone as AV bay.

View attachment 253682

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Nothing wrong with tinfoil. I use it to mix up small batches and if I have to stand something up while curing I find wax paper the best, inexpensive, easy to pull off and readily available.

Ok, it's a mouthful (I forgot to update the thread).

Once the motor mount tube arrived, I can actually build this thing!

I glued the forward centering ring in, drilled a hole in it for the eye bolt. The kevlar was looking like it wants to come undone so I had to remove it and reinstall it (impossible with 3" tubes, so I devised a clever system to allow this) to make repairs. Once that's done, I beveled the fin with a couple of files and a block plane (block plane made short work of beveling fiberglass but unfortunately it also dulls blades as well). Once that's done, the fin is (loosely) glued on. Now I need some chopsticks so I can use it to reinforce the fin. Anyone know where I can get some disposable chopsticks?

Walmart or a supermarket would be my 1st choice but a Chinese restaurant certainly have them.

I'm nearly finished. Just one more external fillet and it's ready to fly!



I decided to put the Intel Inside sticker on the rocket... I got it from a recent CPU purchase. Not sure where I can get more of these stickers...

Sticking with single deployment? Cable-cutter or tender descender?

I'm doing single deployment for now. If I want to dual deploy I will have to add a payload section

Haha, I see a Rudy's cup in the background. I could go for some Rudy's right now.

taiwanluthiers said:

I'm doing single deployment for now. If I want to dual deploy I will have to add a payload section

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You don't have to. You could try a cable-cutter or tender descender. My cable-cutter works great with my Leviathan, which is about the same size.

Looks good. I can't wait to build and fly mine. I'm thinking I might try HEDD with either motor deploy or a BP well in the nose cone, and probably an Archtype cable cutter. The club I fly with does have enough space to fly single deploy to 4-5K so I may just fly motor eject, possibly with a tracker.

The problem is, space is already tight with one parachute, chute protector, etc. and if you put a 6XL grain case in it, it's going to leave maybe 3" of space for recovery harness. So it means I really do need a payload bay to fit all that hardware...

taiwanluthiers said:

The problem is, space is already tight with one parachute, chute protector, etc. and if you put a 6XL grain case in it, it's going to leave maybe 3" of space for recovery harness. So it means I really do need a payload bay to fit all that hardware...

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Definitely, but the archetype cable cutter takes up very little space since it locks alongside the bundled chute. A HEDD setup like the Punisher is probably better, but a cable cutter could still work.

A little update...



I made a quick order at Rocketry Warehouse. I wanted the option to Dual Deploy but there isn't enough room in the rocket for 2 parachutes, a tender descender (or cable cutter), and 6XL motors. So I added a payload section.

The problem is this payload section in addition to the second parachute is projected to add about 1 kilogram to the weight of the rocket, and that means H144 is simmed to fly under 600 feet (which I am not even sure if it's safe) so most likely I'll remove the payload section for lower powered motors. However it looks like if I stuck a 6XL motor in it, it will fly to about 8000 feet and with dual deploy it should be a perfect rocket for L2.

taiwanluthiers; I am building the exact same rocket for an L1 cert attempt in April. I also bought the components to convert to dual deploy (my first), but will use motor deploy with no payload or AV bay for the cert attempt on an H148. A few questions if you don't mind; what is the length of the body tube for the payload section that you used? I would love to see a picture of the exact configuration of the AV bay so I can see different approaches and best practices. What parachute sizes are you using for single deploy and dual deploy? Did you clear coat the rocket - looks pretty shiny : ). PS: I am still waiting for my decal set for the rocket; 2 customer service emails, a phone call and 2 TRF message and no response yet. I saw the Rocketry Warehouse post yesterday and that the are correcting operational issues, so I hope to hear from them soon. Thnx- for any info you can provide.

The payload tube is just 12" long, I ordered it that way from RW. They have been getting better, as the order was sent out almost immediately rather than taking forever. For single deploy (no payload section) I'll just use the top flight 30" chute, but for DD I will use the military surplus 18" chute for drogue, and the 60" chute for main (again also military surplus). Problem is the 60" military chute weights about 12 oz from what I hear, and that will really kill some altitude.

I couldn't find 16" tubes and I am not equipped to cut G12 tubes at all. I didn't spray any finish on the rocket, it is completely naked. As for ejection cannister I plan on just making a small well out of paper or tape, and fill that with blackpowder then insert E match. I will do it at the launch site.

I don't have a good enough camera to get a good picture of it... the iphone is too grainy for this

taiwanluthiers; I bought a 24 inch colored tube from Rocketry Warehouse and they cut it for me to 16 inches. They have an option for a "custom cut" for $3.00 that allows you to get the length you want from the stock size. Also, instead of chop sticks in the future you may want to consider this source which is for fiberglass hollow kite rods to use as gussets on the motor tube and inner fillet area: https://goodwinds.com/fiberglass/filament-wound-epoxy-tubing.html