My Roadmap from Level 1 to Level 3

[mikekebert]

I built my first model rocket at cub scout camp when I was 8 or 9. A few decades and about a dozen Estes models later, I earned my Level 1 certification on July 31st, 2021 at LDRS 39. What a great event! With the help of UROC and Tripoli staff, some total strangers, and some beginner's luck, my certification flight went about as perfectly as one could hope for. Here are a few pictures if you're interested: https://www.rocketryforum.com/threads/ldrs-39.154954/page-5#post-2165708

Now I'm hooked more than ever.

I've laid out a roadmap for myself to work up from Level 1 to Level 3, slow and steady. I live 4+ hours from any high power clubs and launch sites I know of, so my launches will be infrequent and it's going to take me a while.

In order to get to Level 3, and sometimes as a fun detour on the way, I have some things I want to explore:

• Electronics. Altimeters, trackers, dual deployment, and cameras.
• The speed of cardboard. I have a big pile of 3" mailing tubes and I'm going to see how far I can push them. With care, I hope to go to about Mach 1.5. See https://www.rocketryforum.com/threads/what-is-the-speed-of-cardboard.161482/ for some of my inspiration. I may need to fiberglass them to get there, and that will be good learning, too. Or I will decide I hate them and switch, we'll see!
• 3D printing. I have a new 3D printer and I would love to make some of the following things for my rockets:
  • Centering rings and bulkheads. With tube sizes that may be off from other rocket supplies, it may be important for me to be able to repeatedly create my own. If these suck, I'll switch to ordering custom cut plywood or give in and skip the mailing tubes.
  • Avionics sleds. I have seen some inspiring work and when well done, printed sleds are so clean and tight.
  • Nose cones. I would love to make some fancy nose cones that allow for tracking devices and adjustable weights. I want to make some harder-to-find shapes as well, such as some elliptical profiles.
  • Drilling guides. I want to be able to reliably place holes for rivets and shear pins in the same place every time. See the next point for the reason why!
• Interchangeable and repeatable parts. I would like to be able to share parts among rockets and more quickly produce replacements for when stuff breaks or gets lost. This could also help me share some useful creations with others.

I have designed a series of rockets that will hopefully take me from early Level 1 up through some 80ish percent L motors. At that point, I hope it will be time for a Level 3 thread.

Blue Star

This rocket has 3 main purposes: allow me to work through a range of 38mm motors, use a single altimeter to deploy at apogee, and to install and use a tracker in the nose cone. Because of the risk of not having a backup deployment method, I hope to be at this stage for a short time. I'll probably launch this one on 3-4 increasingly powerful I motors.

Deep Blue Star

This rocket is a big step up in complexity because I'm looking to get redundant dual deploy working. It uses the exact same booster and nose cone as Blue Star to help minimize new work and unknowns. This one should fly on 3 different J motors I have picked out.

Green Star

This rocket will use the same redundant dual deploy e-bay as Deep Blue Star. New elements will include a nose cone tuned for flights at 80%+ of Mach 1 and a booster built for 54mm motors. I hope to fly this one on high Js and some low Ks.

Deep Green Star

This rocket will use the same nose cone and booster as Green Star. The new element here is an extended e-bay to allow space for cameras and to improve the stability margin for rockets approaching or exceeding Mach 1. I want to fly this one on low to mid K motors.

Deep Red Star

The final rocket in the series is the craziest and may not be possible with mailing tubes at all (or would require fiberglassing them). It uses the extended e-bay from Deep Green Star but includes a new booster that will be a minimum diameter 75 mm setup. The nose cone will be exactly the same as the Green Stars but will be new simply so I can paint it red. If this rocket ever comes to be, I want to fly it on high K and from low to 80%ish L motors.

Some general notes about the rockets:

• All the boosters except for Deep Red will feature 3 or 4 centering rings and through-the-wall fin mounting.
• I went with low-span trapezoidal fins with long roots to maximize strength and minimize flutter. The body tube extends just beyond the fins to minimize the chances of the fins breaking off. At the lowest level, I'll be using 1/8" basswood, and I'll beef the fins up as needed.
• The launch lugs depicted in the images are just used as placeholders for 1010 rail buttons. When I find a way to bring those in to OpenRocket, I'll swap them out. The rail buttons will be screwed into centering rings for mounting strength.
• Just about everything will be epoxied. I'm pretty comfortable working with epoxy and I will need all the strength I can get.
• I aimed for stability margins of around 1.5 for sub-Mach rockets and for around 2 (or as close as I could get to 2) for Mach+ rockets.
• I used an elliptical nose cone for flights up to Mach .8 and an LV-Hack nose cone for faster than that.

After Deep Red Star, I should have experience with tracking, dual deployment, fiberglass and epoxies, 5-7 ft. rockets, and a minimum of 15-20 launches all the way up to high L motors. I may find that's not enough prep for Level 3, but from where I stand now, I hope it is.

There will be changes and challenges along the way, but man is it going to be fun!

 

[tim cubbedge]

Good luck!

 

[troj]

I'll admit, when I first saw this, I thought it was going to be a rapid progression from 1 to 3. I'm pleasantly surprised by your plan.

One thing you might consider - in your Blue Star phase, you talk about a single device for deployment. You might consider adding a second altimeter. You have tracking in this phase, so I'd get one altimeter that has integrating tracking, and a second less expensive altimeter whose purpose is backup deployment.

-Kevin

 

[mikekebert]

One thing you might consider - in your Blue Star phase, you talk about a single device for deployment. You might consider adding a second altimeter. You have tracking in this phase, so I'd get one altimeter that has integrating tracking, and a second less expensive altimeter whose purpose is backup deployment.

Maybe I should just jump straight to redundant deployment. The cost of the second altimeter is almost certainly less than the cost of coming in ballistic because of a failed primary deployment...

 

[MJW]

Maybe I should just jump straight to redundant deployment. The cost of the second altimeter is almost certainly less than the cost of coming in ballistic because of a failed primary deployment...

For smaller motors you can use the motor delay charge for redundant deployment at apogee. Big motors tend to have sealed forward closures, but definitely not an issue with 54/38 diameter cases. For single deploy this gives full redundancy while risking only a single FC. With dual deploy this will at least blow the rocket into two pieces and get your drouge out so ballistic return will not happen. Even with dual FCs, it's a good idea to set the motor delay and charge as a backup just in case there is a problem with the electronics.

 

[troj]

Maybe I should just jump straight to redundant deployment. The cost of the second altimeter is almost certainly less than the cost of coming in ballistic because of a failed primary deployment...

It's what I would suggest.

You can use motor deployment as a backup, but electronics tend to be more reliable in terms of timing.

 

[Michael L]

Maybe I should just jump straight to redundant deployment. The cost of the second altimeter is almost certainly less than the cost of coming in ballistic because of a failed primary deployment...

Due to our launch location L1 rockets have to have redundant dual deploy (club rules). I am currently in the process of modifying my LOC IV for redundant dual deploy. I modified my nosecone. I put a TeleMetrum 3.0 in the nosecone. The Av bay will have two EasyMini's installed for the redundant dual deploy piece by this afternoon. I've also modified my LOC Graduator for redundant dual deploy. To me it makes sense if you plan to move up in certification. YMMV

 

[troj]

I put a TeleMetrum 3.0 in the nosecone. The Av bay will have two EasyMini's installed for the redundant dual deploy piece by this afternoon.

Why not just use the TeleMetrum in place of one of the Easy Minis?

It doesn't *hurt* to do what you're doing, but you could remove one device.

 

[Michael L]

I absolutely could do that but I'm thinking down the road, higher altitude (I think we are cleared to 50k now), and separating the tracker from the recovery devices.

I am also following one of the long time L2 guys method and the suggestions of our L3 guy. Our recovery area is huge but it's sprinkled with oilfield equipment (that belongs to the company I work for lol) so we take extra measures to keep them "happy". You are correct though. The Telemetrum works just fine for the second device. I'll probably do the same thing when I build my L2 rocket this winter.

 

[Buckeye]

Due to our launch location L1 rockets have to have redundant dual deploy (club rules).

This sounds like an overly-harsh rule to me, so I looked it up on the 4CRA link in your signature:

"All high power launches are required to have redundant ejection systems aboard. At a minimum, all HP flights will have two completely independent systems for ejection of a recovery device at apogee. These systems can be in the form of a motor ejection charge with a flight computer controlled ejection charge, or two flight computers controlling separate ejection charges."

So, one flight computer + motor ejection will suffice for the apogee event. It doesn't say anything about dual deploy or main event.

My approach would be one altimeter controlling the apogee and main plus motor backup for the apogee. This is how I run dual deploy in 90% of my HPR flights. Simple and plenty safe.

 

[Michael L]

This sounds like an overly-harsh rule to me, so I looked it up on the 4CRA link in your signature:

"All high power launches are required to have redundant ejection systems aboard. At a minimum, all HP flights will have two completely independent systems for ejection of a recovery device at apogee. These systems can be in the form of a motor ejection charge with a flight computer controlled ejection charge, or two flight computers controlling separate ejection charges."

So, one flight computer + motor ejection will suffice for the apogee event. It doesn't say anything about dual deploy or main event.

My approach would be one altimeter controlling the apogee and main plus motor backup for the apogee. This is how I run dual deploy in 90% of my HPR flights. Simple and plenty safe.

You wouldn't be the first to say that, or the last. It's a fairly recent change that I think is related to the higher altitude capabilities but seeing it in print I don't thing it's all that harsh. If a 60 pound rocket comes in ballistic and hits an oil storage tank (not likely to happen btw) that would be bad.

I bold faced my choice. I don't like motor ejection but I guess if it's a backup I shouldn't really care. I know it works, I used it for my L1 cert, but if I get the sim wrong (which I did), or I need 1s off of the built in motor delay charge (I did for the second launch on an I), which is nearly impossible to nail down, I end up with early deployment or late deployment. At least with a flight computer, assuming that it works, I get apogee deployment and good chute deployment... I think. Up until now I've always flown with motor ejection. I have the flight computers. My last dual deployment attempt was in an Apogee Aspire (gross overkill I know) and I learned the lesson that not all ignitors will fire on 4V. :/ After two months of laying out in the desert I eventually recovered the rocket. I used everything I could off of it and rebuilt it. When it flies in November I'll have the right igniters. The igniters that I used fired great at 8V (dead 9V battery).

 

[Buckeye]

You wouldn't be the first to say that, or the last. It's a fairly recent change that I think is related to the higher altitude capabilities but seeing it in print I don't thing it's all that harsh. If a 60 pound rocket comes in ballistic and hits an oil storage tank (not likely to happen btw) that would be bad.

I bold faced my choice. I don't like motor ejection but I guess if it's a backup I shouldn't really care. I know it works, I used it for my L1 cert, but if I get the sim wrong (which I did), or I need 1s off of the built in motor delay charge (I did for the second launch on an I), which is nearly impossible to nail down, I end up with early deployment or late deployment. At least with a flight computer, assuming that it works, I get apogee deployment and good chute deployment... I think. Up until now I've always flown with motor ejection. I have the flight computers. My last dual deployment attempt was in an Apogee Aspire (gross overkill I know) and I learned the lesson that not all ignitors will fire on 4V. :/ After two months of laying out in the desert I eventually recovered the rocket. I used everything I could off of it and rebuilt it. When it flies in November I'll have the right igniters. The igniters that I used fired great at 8V (dead 9V battery).

All good points. If there is a need for a rule on redundant ejection systems, then the apogee deployment is the most critical. Even a model rocket coming in ballistic can do a lot of damage. Higher altitude rockets have the added risk of not being seen. For this reason, it baffles me that night launches and multi-rocket drag races are accepted practices. For a hobby that enforces lots of local and national safety rules, these two are disasters waiting to happen because people may not see the rockets (light failure) or become distracted when many are in the air at the same time.

For motor ejection to work as a good back up, two things are needed:

1. The delay time needs to be sufficiently longer than the optimal due to variation. If is is not at least 2 seconds greater than optimal, I take it out.

2. The motor charge needs enough oomph to separate the rocket. HPR through 54mm come with 1.4 grams of BP. This is usually plenty for up to 4" airframes, in my experience.

 

[Michael L]

I so invested in the way I'm doing it I'm not going to change anything. I just finished the nosecone mod. It looks like I drilled holes in the wrong place but those are really just for "weight savings" The idea is to reuse the nosecone bay when I build my winter project (L2 I hope). BTW - that puts me on a 1 year cycle. I watched HP launches for a year while building a Graduator and LOC IV, the next year (this one) I got my L1, if all goes well I'll get my L2 next year.

When used with a single battery my little power board makes it easy to charge the battery

 

[Michael L]

All good points. If there is a need for a rule on redundant ejection systems, then the apogee deployment is the most critical. Even a model rocket coming in ballistic can do a lot of damage. Higher altitude rockets have the added risk of not being seen. For this reason, it baffles me that night launches and multi-rocket drag races are accepted practices. For a hobby that enforces lots of local and national safety rules, these two are disasters waiting to happen because people may not see the rockets (light failure) or become distracted when many are in the air at the same time.

For motor ejection to work as a good back up, two things are needed:

1. The delay time needs to be sufficiently longer than the optimal due to variation. If is is not at least 2 seconds greater than optimal, I take it out.

2. The motor charge needs enough oomph to separate the rocket. HPR through 54mm come with 1.4 grams of BP. This is usually plenty for up to 4" airframes, in my experience.

Delay time has always been the pita for me. I only recently got to where I can somewhat trust my sim. I weighed an ejection charge on a Cesaroni 5 grain H motor and that's exactly what it was. I wondered if that was typical.

I can't even imagine launching at night. We are strictly one launch at a time. Every now and then the college folks will come out and launch mid and low power but most of the time they bring out fairly complicated HP rockets

 

[Titan II]

HPR through 54mm come with 1.4 grams of BP.

Really?

This is from the CTI directions:

NOTE: The ejection charge on all Pro29 motors is 1.2g of FFFFG black powder.

NOTE: The ejection charge on all Pro38 motors is 1.3g of FFFFG black powder.

NOTE: The ejection charge on Pro54 motors is 2.0g of FFFFG black powder.

 

[Michael L]

Granted my little digital scale is not the best but the Pro38 charge I dumped was 1.4g. I've since switched to a balanced beam scale. We'll see what I dump out next month

 

[Titan II]

The point was that not all HPR motors through 54mm come with 1.4 grams. There are minor manufacturing variances.

 

[MJW]

If you're using redundant deployment, you're likely using more BP than comes with the motor, redundant dual deployment almost certainly. The point is regardless of how much BP a specific motor comes with folks should always measure and ground test instead of just dumping a vial and hoping it's close enough.

 

[Steve Shannon]

@mikekebert
I’m delighted that you have chosen a course that’s mapped to skills rather than trying to get L2 and L3 as quickly as possible. You’ll do very well.
Thank you!

 

[mtnmanak]

Outstanding plan - well thought out and it looks like it will be a lot of fun!

You would be surprised how small of a space you can get a redundant dual deploy system crammed into. I have done it in 38mm minimum diameter rockets by using a long narrow sled. But for your purposes, it is really quite easy with these larger tubes.

If you want to standardize, 3D printed sleds are the way to go. These ones from Additive Aerospace are great (although, now that you have your 3D printer, maybe you can come up with something even better!):

https://www.additiveaerospace.com/collections/altimeter-sleds
On one build, I used a 54mm sled in a 2.6" rocket that has a Raven 4 on one side and a Stratologger CF on the other.

If you are using a 3" tube, it is even easier because you can fit the Raven perch on one side - here is redundant dual deploy sled I use in my 3" rockets:

 

[Buckeye]

Really?

This is from the CTI directions:

NOTE: The ejection charge on all Pro29 motors is 1.2g of FFFFG black powder.

NOTE: The ejection charge on all Pro38 motors is 1.3g of FFFFG black powder.

NOTE: The ejection charge on Pro54 motors is 2.0g of FFFFG black powder.

Sorry, I was referring to Aerotech motors.

 

[mikekebert]

For smaller motors you can use the motor delay charge for redundant deployment at apogee. Big motors tend to have sealed forward closures, but definitely not an issue with 54/38 diameter cases. For single deploy this gives full redundancy while risking only a single FC. With dual deploy this will at least blow the rocket into two pieces and get your drogue out so ballistic return will not happen. Even with dual FCs, it's a good idea to set the motor delay and charge as a backup just in case there is a problem with the electronics.

It's what I would suggest.

You can use motor deployment as a backup, but electronics tend to be more reliable in terms of timing.

Motor delay isn't a bad option as a redundant method, especially when trying to reduce the amount of electronics in a build. I looked at modifying my Blue Star rocket design to accommodate a motor delay charge, but there wasn't enough space to squeeze the main chute in on the side that would open with that charge (my mailing tubes are 24" and I run out of room on the booster side for both chutes and the motor mount). I rearranged some of the tubes and couplers to see if I could get it to work, and it got pretty awkward--this particular design works better as electronic deploy only.

Once I have two electronic devices in the build, it's getting to be like 90% similar with the Deep Blue Star which has a drogue for DD and would also work with a motor deployment backup. About the only thing to change would be the tubes and positioning for the e-bay (to make a little more room for the drogue chute). I might use a few dollars worth of extra tubes to make an e-bay for each rocket, or maybe I'll just skip straight to the Deep Blue Star design. I'll keep you posted.

 

[mikekebert]

@mikekebert
I’m delighted that you have chosen a course that’s mapped to skills rather than trying to get L2 and L3 as quickly as possible. You’ll do very well.
Thank you!

Outstanding plan - well thought out and it looks like it will be a lot of fun!

You would be surprised how small of a space you can get a redundant dual deploy system crammed into. I have done it in 38mm minimum diameter rockets by using a long narrow sled. But for your purposes, it is really quite easy with these larger tubes.

If you want to standardize, 3D printed sleds are the way to go. These ones from Additive Aerospace are great (although, now that you have your 3D printer, maybe you can come up with something even better!):

https://www.additiveaerospace.com/collections/altimeter-sleds
On one build, I used a 54mm sled in a 2.6" rocket that has a Raven 4 on one side and a Stratologger CF on the other.

If you are using a 3" tube, it is even easier because you can fit the Raven perch on one side - here is redundant dual deploy sled I use in my 3" rockets:

I appreciate the positive feedback!

Those sleds from Additive Aerospace look really good. I should probably get one for 1) inspiration and 2) to make sure I have a way to launch in case I run out of time to design and print my own.

 

[mtnmanak]

I appreciate the positive feedback!

Those sleds from Additive Aerospace look really good. I should probably get one for 1) inspiration and 2) to make sure I have a way to launch in case I run out of time to design and print my own.

Agree - it would be a good idea to get a variety of these kinds of 3D printed things for both inventory and inspiration. I don't have a 3D printer (yet!), but I do have a CNC machine and often use other people's products as inspiration for my own designs.

For these Additive Aerospace sleds, I do love them, but, if I was designing my own, I would really push to see if I could improve the switch location - preferably more towards the middle of the sled. The way they have it with the switch bracket at the end of the sled forces you into some compromises - especially when the couplers are short.

Another company to look at for 3D printed sled inspiration is Badass Rocketry.

https://www.badassrocketry.com/shop

 

[thzero]

Seem kinda heavy.

 

[troj]

I might use a few dollars worth of extra tubes to make an e-bay for each rocket, or maybe I'll just skip straight to the Deep Blue Star design. I'll keep you posted.

Definitely keep us posted! As you learn more and gain skill and experience, I'm betting you'll make some adjustments to your plans.

Regardless, it's impressive to see a well thought-out roadmap for getting from A to B, and I'm betting you're going to have a lot of fun along the way