Mega Initiator build for L1 Cert

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achaskin

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First of all, thanks to the community for helping with my first HPR build.
It's finally come together, and although I made some mistakes with the paint that just couldn't be fixed, I am overall satisfied.
This Mega Initiator is weighing in just over 3.5 pounds/1640 grams. It will be carrying a 200 gram payload of a makeshift E bay
with an RF beacon and an Estes Altimeter (just to simplify things). Ive also purchased and AstroCam kit just for the HD camera
so I'll get on-flight footage to post later!

Next is time for Simulations and a full dress rehearsal. Im guessing this heavy guy might need an I motor vs an H for a nice flight.
Let me know what you think!
 

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Donnager

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My first flight with the Mega initiator was an I-280. You may be able to use a punchy H like an H-550, but you'll need to check your sims and get your delay right.
 

Tractionengines

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Nice build. Good luck with the flight. Make a check sheet.... and remember HAVE FUN.

Regarding motors: Update your sims with no motor, "ready to fly weight and measured Center of Gravity". Then override the sim for your actual build. Then "play" with motor options. You want 50fps off the rail. Also if motor eject, the optimal delay to be close an available time, or in the adjustable range for your motor, if adjustable.

There are punchy H's but you probably don't need it. You said only 3.5 lbs plus some "small extras". To meet "minimum requirements" you want 5:1 average-thrust to weight ratio. [ Some places allow 3:1 but I would NOT do that for a certification flight, too slow or needs a very long guide rail. ]

For example if your ready to fly weight WITH motor is 4lbs, that's 18 Newtons. So 5x is 90 Newtons.

Personally I would look at sims for 29mm DMS motors. H169 Super White Lightning, H182 Redline, H195 New Blue Thunder, etc. (or their equivalent 38mm versions.) These are twice the minimum, so should give a good flight with minimal chance of fin flutter, or drag separation. If you want more altitude there's the I's in this thrust range. YMMV

Other's will give you their opinions and processes too. Ultimately its your flight.
 

Alan R

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my L1 rocket weighs in with motor at 3.3 lbs. It flies just fine on H100 and larger. How high do you want to go?
 

Adam3836

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Very nice looking rocket
Good luck
 

Zeta

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Achaskin,

an H148 will get you 1200 feet
an H 178 will get you 1700 feet
 

teepot

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If you haven't already take a look at Thrustcurve to help you pick a motor.
 

gary7

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Looks very nice! Best wishes for your cert attempt. You'll do fine!
Not to hijack your thread and this isn't exactly an Aerotech Mega Initiator, but is my scratch built "stubby" Initiator. 5.5 inch Loc air frame and nose; fins to scale; 66.5 inches tall. H550!

Capture.JPG 2.JPG
 

achaskin

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The motor chosen was an i140W Aerotech DMS with 10 seconds delay. Apogee was just above 2000ft and popped the chute exactly at nose over. The rocket is 4 pounds with a 200g payload of RF beacon, Altimeter, and Hebrew prayer for safe Travels (Luck Charm). The 335 N-sec made it scream like a bat out of hell!
Check out the roll from the 1mm canted fins. Flawless and awesome, can’t wait to bring it back out to the field!!
57062EB9-8038-457E-A470-20CA2493187F.jpeg

 

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