Level 1 Certification Success!

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downhill_D

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So I managed to get my Level 1 finally...wanted it 20 years ago and just never finished.

I used a loc precision graduator with an H97-10 and it was a fantastic flight. I will be waiting to go level 2 as I feel I have more to learn and want to bask in the joy of flying high with H and I motors for a bit! I used a few old techniques in my build of the graduator, including making a second forward centering ring and adding two part foam inside the fin can. I used all 30 min bsi and added tubular nylon for a little extra room for expansion on the shock cord at apogee.

The inspection and flight went really, really well and the president of my club asked very good questions that required me to know A LOT about my rocket (very appreciative of this!) BUT as I watched the flight the drogue had gotten just enough heat from behind the Nomex blanket that it stuck to itself the entire fall. Luckily, I had been practicing with the JLCR and the 48" chute main hit at about 254 ft!!!...I had set it to 500. It slowed to a nice 6mph just in time. Yep...I was holding my breath the whole time. I got lucky and the drogue chute was actually okay but literally just enough to stop it from unfolding.

So, I learned:
-I should make a baffle and/or use a stuff of dog barf to prevent hot gasses, if even a little, gets through the Nomex burrito folds...it could be disastrous.
-using a low impulse H motor (baby H) so I could see almost my whole flight was the way to go! Highly recommend this motor for this rocket.
-if you wait all day to load the casing and sunset is coming you might have waited too long...that said I got an amazing picture from a photographer, right at sunset, right before it was too late. I unfortunately got no video but the pictures are worth a thousand words to me.

-the graduator is an excellent Level 1 rocket (only) with good building techniques and a great track record!

-using a simulation program is very key to my success. you can use any of the free ones or Rocksim (I purchased it) and it helped me understand every change I made and its effect.

-if anything, I really appreciate everyone here and their advice. I sometimes read through here for hours (apogee website too). This hobby REQUIRES you to learn from others if your going to do well. Don't be afraid to ask questions...especially for a certification...I am glad I never stopped asking questions. You all on rocketry forum helped make this possible too-so thank you! Now to go fly some H and I motors...there goes the wallet...about a mile up ;)



Will attach photos once uploaded.
 
Thank you everyone!

Picture time!
 

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Which reminds me:

My camera wasn't working and I wanted to track my rocket so luckily this guy gets allllllllll the credit for this shot: “cj_that_photo_guy” (insta) took the sunset shot! Nice photography!

He took the shots unbeknownst to me! Lucky day for my Level 1!

Thank you!
 
Thank you! It was certainly stressful in the moment but well worth the effort!
 
Congrats on your L1, and great to hear about your mind set on learning as you go. Great write up and pics.

As you work the process and get proficient with prep taking video and pics gets easier, until you have: GPS, JL3, JLCR, other altimeters, DD charges, ground camera, etc lol.

The difference with just messing around and science is recording data.

~John
 
Congrats. Welcome to HPR. Sounds like you have a great attitude to learning :).

That is a great launch shot!

I would suggest you set the main to come out higher up next time, but I think you have already figured that out. Learn to design for sub-optimal conditions, particularly in recovery, and your rockets will thank you. It makes for safer flying too. Up is easy, down is hard.

FWIW I usually suggest that anyone certifying gives their camera to someone else to get pics of the event. Takes the stress off the flyer with everything else that is going on. YMMV.
 
Congrats on your flight. I also used a LOC kit. recommend them to anyone. I am on the trial version of rocksim, any good tips you have? Tha nks, Dave.
 
Congrats on your flight. I also used a LOC kit. recommend them to anyone. I am on the trial version of rocksim, any good tips you have? Tha nks, Dave.
Yes! Use the mass override and CG override feature once the rocket is built. I failed to do so but weighing each part as you enter themis the way to go. Do NOT rely on the already built models available to open. They are somewhat outdated and will most likely be different from your actual model-make the rocket yourself from scratch to learn the program-add each piece and then compare after if you feel you missed something. I spent some time reading apogee articles about the program that will teach you things you wouldnt know like setting apogee for the simulation ending point from the motor selection page and changing weather options to your own. Also, the 2D simulation is a very important one to run-you will see how your model behaves in realtime based on your entries.

Most important have fun with it-once you feel your model is correctly built in rocksim the flight simulation page will give you really important info like whether it was still on the way up or falling really fast when it deploys. I can run motors and have good idea of what will really happen.

your center of drag, the one thing we cannot really know ahead of time can be figured out once you have real data from a real flight. You can adjust it to match the data you get from an altimeter to make your simulations that much more accurate. For example:
My rocket simulated 3000 ft before flight and actually flew ~2400ft.

Just remember it is a simulator so if you put bad data (including measurements) into the program you wont get good results.

Finally: each simulator gives different results-try each one and see what variations you get. I am just personally sold on rocksim-I just prefer it.
 
Thank you again everyone! Now, here is a question I have regarding a flight. We just had a launch last weekend and I basked in the glory of jamming H motors in rockets...pretty much awesome. I cant seem to upload my video of my Graduator kit with an H180-10W last weekend BUT The question is:

Why did it whistle in flight during coast? It took off and then whistled toward the end, very audibly

There are no interrupted/split fins, it has two external delrin rail buttons (one has an 1/8th hole for the altimeter) and three holes drilled in the aft motor mount for the two part foam I poured in.

Some of the useful flight info:
3222 feet
516 mph.
29g’s max with avg 21.3 g’s

Was it the speed of the rocket causing the whistle or old propellant?
 
Looks like your fins are square. Fluids don't like sharp corners, they are inefficient and bleed energy. Sounds like some of that energy became a whistle

That sounds likely. haha! I recently learned about the triangular fins (loc lil nuke for example) being more ideal for breaking mach so a square edged design would hold more pressure back? Even with the aerofoil of the fins that is a lot of pressure. Fascinating really.
 
In extremely general terms, a round to tapered airfoil is good in subsonic flight. the elliptical or superelliptic leading profile redirects the flow and the tapered trailing edge reduces flow separation (think of base drag and boattails).
For supersonic flights where shocks form, the tapered leading edge creates just a single shock angle which helps minimize the disturbance.
 
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