L Padre - A minimum diameter Big Daddy

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T34zac

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Sometime earlier this year, or late last year, in some thread I can no longer remember, I alluded to a a project of mine that was in the concept stage at the time. I had been fascinated with how far you can push the Estes Big Daddy rockets using the parts that come with the kit, and I ended up building one with a 54mm motor mount, fiberglassing the body tube and fins. So far I've yet to fly this rocket, it's been put on the backburner while I work on projects for LDRS, XPRS, and beyond.
Fiberglassed Big Daddy.jpg


So for LDRS, I decided to work on the version of the Big Daddy that's even more extreme than the version with the 54mm motor mount: minimum diameter Big Daddy.

So back in October I began flirting with the idea of shoving a CTI L910 into a Big Daddy shaped airframe. I went ahead and started modeling it in Fusion 360 to see just how possible this idea could be.

Concept.png


Based off this model, there should be just enough room to fit electronics and recovery into the nose cone. And yes, the motor casing is being used as the nose cone shoulder. This overall design ended up a few inches longer and a slight bit larger in diameter to the original kit. but on its own, looks just like the real deal.

A couple months later, I put an order into madcow for a nosecone and body tube. It was time this became a reality. After receiving my parts, I got to work cutting the body tube to just the right length to make sure the nosecone would be nice and snug on top the motor casing. The body tube ended up being 11.375" long, just 1.375" longer than the kit. And the nose cone is 9.75", just 0.75" longer than the kit. Overall the rocket is just 2.125" longer than the kit, pretty good for a horrendously oversized motor for it.
Body tube and nose fit.jpg


For a while I didn't touch this project to work on other rockets and get ready for the early flying season in the winter/early spring. It wasn't until early June that I actually cut the fins out of 1/8" G10. It was also around this time that I packed all my belongings and left the east coast, relocating myself to Arizona. A few weeks ago I got working on sanding down the fins to the correct size and finally getting them tacked on then applying some hefty fillets.
Fins attached.jpg


Around this time I decided that it would be cool to get it ready in time for LDRS and fly it there, and so a majority of my free time over the past month has been spent working on getting it flight ready. Some friends and I had concern about fin flutter at the speeds that Open Rocket and RasAero II were predicting, so I decided that carbon tip to tip would be a good idea. So after an afternoon at a friends house, helping him do a carbon layup on one of his own projects, the newly dubbed L Padre had a layer of carbon on the fins.
Carbon tip to tip.jpg


The av-bay has been a nightmare of a problem that's been looming over the build since the beginning. I'd have to come up with some creative solutions to get it to work out and save enough room for a parachute and shock cord. Originally the plan was to mount a Raven 4 near the tip of the nosecone, but that idea never panned out the way I wanted. So after some thinking, I realized I could fit an Easy Mini, a screw switch, and 1s LiPo battery around the forward closure of the motor case. Using a 29mm motor mount, a 54mm body tube section, a 75-54mm centering ring, and a 54-29mm centering ring, I came up with a short av-bay that fits neatly around the forward closure of a Pro75 motor case. I will be using a 3d printed shell to go around the av-bay to protect it at and after apogee ejection.
AV-bay mock up.jpg

AV-bay attached to motor.jpg


The whole assembly leaves about 2 to 3 inches of room in the tip of the nosecone to fit a shock cord and parachute. Just enough room for a short kevlar line, a 24" thin mill cute, and cable cutter.

Now that the av-bay was sorted out, all that was left to do was paint and get decals. Stickershock was commissioned for the custom decals, inspired by the retro style of Big Daddy. So I got some primer, gloss black paint, and gloss clear coat and got to work. Earlier today was the end result and I couldn't be happier with how well this turned out. Easily the nicest looking rocket I've put together so far, it's so unfortunate that Mach 2.4 will not be kind to this finish.
Decals applied.jpg


Oh and I built a new launch tower that will also be debuting at LDRS next weekend.
L Padre in Launch Tower.jpg


I'll be aiming for a Saturday or Sunday launch of L Padre, so keep an eye out for it if you make it out to LDRS!
 

Tim51

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Congratulations on pushing the envelope, and good luck with the flight. It looks beautiful and looking forward to reading your launch report. Just one question from the back row: isn't there a risk that Mach 2.4 will delaminate the carbon layup on the fins? (Personally I've never flown anything like this so my question is just curiousity based on other MD threads).
 

T34zac

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Congratulations on pushing the envelope, and good luck with the flight. It looks beautiful and looking forward to reading your launch report. Just one question from the back row: isn't there a risk that Mach 2.4 will delaminate the carbon layup on the fins? (Personally I've never flown anything like this so my question is just curiousity based on other MD threads).
It’s definitely a possibility. But I don’t think it’s going to be at that speed long enough to heat the epoxy enough to cause that. The motor only has a 3 second burn and the airframe is quite draggy, so it will be slowing significantly after burnout.

I am fully expecting the decals and some of the paint to come off however.
 
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T34zac

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Alright so I’d be lying if I said the build was 100% completed when I made the original post. I still had an AV-bay and recovery gear to sort out.

I mentioned that the motor case actually acts as the nose cone shoulder for coupling to the body tube. Well this takes up about half the available space in the nose cone. Leaving a small amount of room to fit an av-bay and recovery gear. So the solution was to take a spare 29mm motor mount, 54mm body tube section, a 75-54mm centering ring, a 54-29mm centering ring, and a few 3d printed parts to assemble an av-bay that fits nicely around the forward closure of a CTI 75mm motor.
636A053D-9238-4E38-8246-3D57529BE476.jpeg


The flight computer I chose is an Altus Metrum Easy mini. Very small dual deploy altimeter, using baro only. A small 3d-printed standoff was made for it so it could sit securely with zip ties, and the battery Occupies the space opposite. And a 3d-printed shell was fit around the whole assembly to protect the av-bay from ejection gasses and landing (hopefully).
3DF03BEE-254F-4158-9912-DE2B3B5A3E58.jpeg

776BF1B4-27CB-4373-BA2B-4CBF7CDE70F6.jpeg


Now this leaves only a tiny bit of room for recovery gear so a 24” thin mill chute from top flight recovery was chosen to do the job. I can fit a 30” or maybe a 36” thin mill chute in the space, but I don’t have one currently so I’m going to be hoping I can secure one at LDRS. The 24” should work out for a ~30fps landing. Harder than I’d like, but it’s a tough rocket.

Attachment point for the recovery gear is pretty simple. I dremeled the threaded rod flat on two sides and drilled a hole through the end, just enough for a small quick link to fit through. The other end of the shock cord is attached to the screw holding the aluminum nose cone tip. This minimizes the amount of room hardware takes up in the extremely limited space.
DE8A0174-5CCE-4238-BD83-B328483F7949.jpeg


Everything fits nice and snug inside. Hindsight shows that I could’ve fit a second easy mini in the av-bay alongside the com spec radio tracker that will be included in the setup. Pretty much all that’s left to do now is drive to Utah and light it up!

It would be greatly appreciated if anyone attending LDRS manages to get pictures or video of the flight. I’ll be doing my best to capture both and track it at the same time.
 

Donnager

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Alright so I’d be lying if I said the build was 100% completed when I made the original post. I still had an AV-bay and recovery gear to sort out.

I mentioned that the motor case actually acts as the nose cone shoulder for coupling to the body tube. Well this takes up about half the available space in the nose cone. Leaving a small amount of room to fit an av-bay and recovery gear. So the solution was to take a spare 29mm motor mount, 54mm body tube section, a 75-54mm centering ring, a 54-29mm centering ring, and a few 3d printed parts to assemble an av-bay that fits nicely around the forward closure of a CTI 75mm motor.
View attachment 474695

The flight computer I chose is an Altus Metrum Easy mini. Very small dual deploy altimeter, using baro only. A small 3d-printed standoff was made for it so it could sit securely with zip ties, and the battery Occupies the space opposite. And a 3d-printed shell was fit around the whole assembly to protect the av-bay from ejection gasses and landing (hopefully).
View attachment 474697
View attachment 474698

Now this leaves only a tiny bit of room for recovery gear so a 24” thin mill chute from top flight recovery was chosen to do the job. I can fit a 30” or maybe a 36” thin mill chute in the space, but I don’t have one currently so I’m going to be hoping I can secure one at LDRS. The 24” should work out for a ~30fps landing. Harder than I’d like, but it’s a tough rocket.

Attachment point for the recovery gear is pretty simple. I dremeled the threaded rod flat on two sides and drilled a hole through the end, just enough for a small quick link to fit through. The other end of the shock cord is attached to the screw holding the aluminum nose cone tip. This minimizes the amount of room hardware takes up in the extremely limited space.
View attachment 474699

Everything fits nice and snug inside. Hindsight shows that I could’ve fit a second easy mini in the av-bay alongside the com spec radio tracker that will be included in the setup. Pretty much all that’s left to do now is drive to Utah and light it up!

It would be greatly appreciated if anyone attending LDRS manages to get pictures or video of the flight. I’ll be doing my best to capture both and track it at the same time.
Nice job. I quit at 54mm in a stock body.
 

T34zac

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Nice job. I quit at 54mm in a stock body.
Haha, yeah I’m still working on that one. Hardest part for me is figuring out how to attach all the recovery. This one was a bit easier on the recovery aspect... somehow.
 

T34zac

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So LDRS 39 is over now and L Padre didn’t get to fly. Sunday morning I had it out in the tower and ready to go, but the cloud cover prevented anything flying over 5,000’ for the majority of the day.

After a while, event organizers wanted to tear down the right side range so only the left side was being used for the rest of the event, and since L Padre was set up in a tower on the right, that meant taking the tower down and going to set it up on the left side with the hopes of clouds clearing up. I wasn’t really in the mood to chase anything at that point so I just took down the tower and started packing my stuff. Unfortunate, but that’s just the way it goes sometimes. I’ll have another chance at flying it later on in September at XPRS.
 

Donnager

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So LDRS 39 is over now and L Padre didn’t get to fly. Sunday morning I had it out in the tower and ready to go, but the cloud cover prevented anything flying over 5,000’ for the majority of the day.

After a while, event organizers wanted to tear down the right side range so only the left side was being used for the rest of the event, and since L Padre was set up in a tower on the right, that meant taking the tower down and going to set it up on the left side with the hopes of clouds clearing up. I wasn’t really in the mood to chase anything at that point so I just took down the tower and started packing my stuff. Unfortunate, but that’s just the way it goes sometimes. I’ll have another chance at flying it later on in September at XPRS.
It happens to the best of us. I have about three or four rockets that have gone "un flown" because of launch conditions. They will continue to marinate......

Their day will come, eventually.
 

Dipstick

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Too bad, I was looking forward to that flight report. Guess I can wait too...
 

T34zac

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It happens to the best of us. I have about three or four rockets that have gone "un flown" because of launch conditions. They will continue to marinate......

Their day will come, eventually.
Most of it was due to time constraints for me. Sure I was there all day Friday-Sunday, but I was helping out with two large projects by @bandman444 on Friday and Saturday that are up a good amount of time and energy (and sleeping on the hotel floor wasn’t helpful either). That said, those two large projects were definitely worth the time and effort.
 

messedupryan

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I saw this sitting on your table at LDRS and was so excited. I never saw it and I thought I'd missed it. Glad to hear I didn't miss it, but sad to hear that you got forced to wait. Best of luck at your next launch!
 

T34zac

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I saw this sitting on your table at LDRS and was so excited. I never saw it and I thought I'd missed it. Glad to hear I didn't miss it, but sad to hear that you got forced to wait. Best of luck at your next launch!
Yeah it was sitting on the table most of the weekend. Each night I brought it back to the hotel to get it a little closer to ready each night. I had the intention of flying it first thing on Sunday morning, but packing the recovery was more of a challenge than anticipated, so I missed the clear part of Sunday morning when it would’ve been able to fly.
 

T34zac

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Thinking I’m going to be delaying the launch of L Padre until LDRS 40. I’ve currently got a number of other projects planned for XPRS.

I’ll bring it along, but there’s no guarantee I’ll fly it. Plus it was originally intended as an LDRS project so it just doesn’t feel as fun to not share it with more of the community.
 
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