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Jr level 1 cert.

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3 weeks 5 days ago #10097 by GrantW
Jr level 1 cert. was created by GrantW
Hi there, for a while I’ve been wanting to get L1 certified and finally had the chance to do it. Unfortunately for me though the club has been closed. I see that it has reopened and was wondering if the Amesbury launch on the 19th was going on, and if it was could someone help me get certified. I am fifteen so I would need to take the test and need spotters/someone to buy the motor (if I’m not mistaken), though I can pay for it of course. If this launch isn’t possible I am fine waiting for the next available Amesbury launch. The rocket is an apogee zephyr and it is ready to rock.

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3 weeks 1 day ago #10112 by ChristineZ
Replied by ChristineZ on topic Jr level 1 cert.
Hi Grant, welcome.
There should be several L1 and above certified members available. The RSO and/or CMASS people can point us out. You would need two L1 members, or just a single L2 or L3 member as a witness.

As for your motor, it would help if you posted what you are looking for? (It needs to be either an H or I impulse certified motor). Some members may have a motor they are willing to sell. Do you have a case if it's a reload?

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3 weeks 14 hours ago - 3 weeks 8 hours ago #10113 by GrantW
Replied by GrantW on topic Jr level 1 cert.
That sounds great! I have a cesaroni 38mm 4 grain casing with two spacers, so I plan to use a H100, though I have rocksim so if there were another motor I can check to see if it’s ok. I believe as of 2020 there is a test too, but I’m not very familiar on how to get/take it, all I know is that it is taken the same day before the flight. I have been studying for it.
Last edit: 3 weeks 8 hours ago by GrantW.

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3 weeks 5 hours ago #10114 by hgreenblatt
Replied by hgreenblatt on topic Jr level 1 cert.
Hi Grant, welcome to the club!!
So far the plan is for us to still launch in Amesbury on the 19th. The field has been hayed but we still need permission from the town, the fire-chief, the weather gods, etc, We will have plenty of info regarding the launch on the website in the days leading up to it.
As far as your motor, the Cesaroni H100 is a 2 grain 38mm motor, so you will need two spacers for your 4 grain case (or a smaller case of course). Do you have those as well?
What is the diameter, length, and weight of your rocket (or is it a kit?) so we can do a rough sim a head of time? Or better, maybe you can email the officers of the club a copy of the Rocsim file.
The club officers will coordinate getting a copy of the exam for you to take in Amesbury.
Good luck!
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2 weeks 6 days ago - 2 weeks 6 days ago #10115 by GrantW
Replied by GrantW on topic Jr level 1 cert.
Thanks for the info. I do have one spacer and one is on the way. The kit is an Apogee Zephyr, and I have done a few rocksim simulations, and the H100 should be stabile and stay at a comfortable altitude with a chute release (2400 ft). I can email the rocksim file too need be.
Last edit: 2 weeks 6 days ago by GrantW.

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2 weeks 6 days ago - 2 weeks 6 days ago #10116 by ChristineZ
Replied by ChristineZ on topic Jr level 1 cert.
Grant, wonderful...

Howard (hgreenblatt) is a good resource. Also you will need a pro38DAT drilling tool to set your ejection charge timing. The H-100 has a 15 second delay. Depending on your flying mass (the sim software, calculates the weight of your rocket from the input mass), your delay will want to be about 8 seconds or less. That means you will need to set the delay grain accordingly.

If you don't already have the drilling tool, don't worry, there are members who do, I always have mine. (I likewise have odd/even increment drilling adaptors and an even increment drilling tool) whereas the proDAT tool is just odd seconds. And there are members who can show you how to do this correctly.

For instance: the H100-15 is a 15 second delay. The rocksim file for the Zephyr indicates an ideal delay of 8.4 seconds (I use Open Rocket). Your delay will vary depending on the mass of your rocket. Best is to "weigh" it fully set up to fly (without the case and motor, but with all the harnesses, parachutes, etc.) and adjust the final build mass in the simulation. Better yet, bring your laptop with you to the launch. If you need a scale to get the correct mass, I believe the club has one, but I can bring one too (I usually don't bring one).

If indeed, your ideal delay is ~8 seconds, that means you need to drill your delay grain down -7 seconds
(15 - 7 = 8 ) If your ideal delay is 7 seconds (due to added mass, you still can do the same drilling, or can use an even adaptor or drill down to 15-8 = 7).

ALL THAT BEING SAID...2400' is awfully high to deploy your main parachute. The Amesbury field is notoriously breezy in a rocket eating direction (sometimes to most times).
Solutions:
Option A ) Smaller parachute (not ideal). You can use a smaller parachute than the one that comes with the rocket, but you risk ground hit damage. The stock 36" chute is going to land you softly at 6.5m/s, Amesbury is a soft field and can sometimes absorb faster descents (unless you hit a hard surface).
Option B ) Chute tender (best). Using a chute tender to hold your parachute together until you reach a lower altitude. This may be your best solution, as your rocket is not set up for dual deployment. The ejection charge will separate your rocket near apogee, then your rocket will tumble to a lower altitude. The chute tender will keep your parachute bundled until a certain set altitude, (eg. 300 to 400 feet A.G.L.) a which point it will release the chute, and your rocket will slowly descend to the ground. This will also get your rocket on the ground somewhat quicker too, because your rocket will descend that first 2000 feet quicker than under parachute. [Your 36" chute, deployed at 2400, will take you ~104 seconds from deployment to ground hit (assuming no wind). With a chute tender, you'll tumble from 2400 to 300 feet, then deploy. Your total time is ~73 seconds to get on the ground.]

Hope that helps, Good luck!
Christine
Last edit: 2 weeks 6 days ago by ChristineZ.
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