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General Rocketry => High Power => Topic started by: David Carter on January 13, 2016, 01:49:28 PM

Title: BB Level 3 project
Post by: David Carter on January 13, 2016, 01:49:28 PM
Having received both Level 1 and Level 2 certification last year, it's time to begin my level 3.

I considered a lot of kits but eventually settled on a custom design and build. This is essentially a Roll Your Own from Rocketry Warehouse with some customization.

This project consists of a 4-inch diameter fiberglass airframe, capable of accommodating up to 75mm M-impulse motors. It is a 3-fin booster design, with lower and upper payload sections for drogue and main chute recovery gear. Topped with a 5:1 Von Karman nose cone, giving the rocket an overall length of 97 inches (length may change. I'll discuss why in a later post). Dry weight, including recovery gear and electronics, rounds out at ~277 ounces (17.3lbs.).

The primary flight computer for this rocket is the Altus Metrum TeleMetrum. The key advantage of using this computer is that it transmits flight information, including location as measured with GPS, via a ham radio telemetry link. Not only does it give you real time feedback about how the flight is going, it also greatly simplifies recovery. The backup is the Pico-AA2.

The rocket will carry onboard a Mobius HD video camera. The main parts of the camera will be carried internally in the electronics bay, while the CCD sensor will be mounted externally facing aft along the body. This will have a 3D printed sensor mount on the outside of the rocket, with the camera itself contained in the electronics bay. I never did like the thought of duct taping a camera to the outside!

In this thread, I'll document the build, as well as pose any questions that come up. In particular, I'll spend some time documenting the electronics bay and the design of the camera mount.
Title: Re: BB Level 3 project
Post by: dbmccann on January 13, 2016, 07:48:31 PM
Sounds very cool.   

Have you seen the shroud for the mobius?   A much neater way to hang the whole thing outside the rocket than duct tape :)  I use a few and enjoy them. 

Title: Re: BB Level 3 project
Post by: David Carter on January 13, 2016, 08:46:03 PM
I have, but I'm not overly impressed. They're still pretty crude and aesthetically unpleasing. I've even printed one to confirm my opinion.

I've got bigger plans... possibly even two cameras, one with a wide angle lens and one with the normal lens. I still haven't decided, but I'm still working on the fit of the printed parts. I'm finding the precision is less than advertised.

I may still have the camera external like with the shroud, but it will be a better shroud.
Title: Re: BB Level 3 project
Post by: David Carter on January 13, 2016, 09:01:19 PM
This is more the kind of shroud I'm interested in. It's essentially half of a Von Karmen nose cone with a conformal shape for my body tube.
Title: Re: BB Level 3 project
Post by: David Carter on January 13, 2016, 09:14:06 PM
The mechanical portion of the build is underway. The motor mount is built, and the fins are attached. Working on all the fillets, but that is taking a lot of time as there are a lot of them. There's also not much room with a 75mm motor mount in a 4" tube. Rocketpoxy all the way.

Since there was no room on the centering rings for an eye bolt, I epoxied a section of nylon shock chord to the motor mount for shock chord attachment. With a standard 75mm motor, this will be a back up to the eye bolt in the motor itself, but it does allow me to fly a 54MM motor with adapter. And backups are never a bad thing.

I used an old pizza box for aligning my fins in the absence of a fin jig. You can never get enough pizza right?
Title: Re: BB Level 3 project
Post by: David Carter on January 13, 2016, 09:15:48 PM
Continued...
Title: Re: BB Level 3 project
Post by: David Carter on January 13, 2016, 09:47:13 PM
In the meantime, I created a custom ebay sled for the electronics. This is essentially a modification of existing designs, but since I had the capability, I tailored it for my electronics.

The main flight computer is the Altus Metrum TeleMetrum which also has GPS for tracking and a real time HAM telemetry link. There's lots of room in my 12 inch ebay for it and its antenna, but for best results the antenna should be vertical. My design includes a very basic antenna support.

The secondary flight computer is a PICO-AA2. Both computers use different batteries, so my battery compartment can accommodate both. The compartment has a screw on cover that will restrain the battery in all dimensions.

This may be overkill in some senses, but hey... because I can!
Title: Re: BB Level 3 project
Post by: RKeller on January 13, 2016, 09:51:06 PM
Really nice build! what 3d printer are you using?
Title: Re: BB Level 3 project
Post by: David Carter on January 13, 2016, 09:55:50 PM
Really nice build! what 3d printer are you using?

Robo 3D R1+. (http://www.robo3d.com (http://www.robo3d.com))
Title: Re: BB Level 3 project
Post by: mdutch on January 14, 2016, 09:34:09 AM
David so far so good on you L3 build and this is a perfect way for me to review everything so I can sign off on the project when the time comes. I noted that you said you were using a nylon strap on the motor mount. This would be fine as all "M" motors don't have an ejection charge that could damage it, but some 54 motors do. So you would need to be careful using those.

Although from the pictures you post here that strap actually looks like a Kevlar strap, which is what I would have recommended and is better suited to withstanding powder burns.

One thing you might want to consider for your build is a tip to tip fiberglass application to beef up the fins to stand up to the G-forces a "M" motor will put the airframe through, especially where fin flutter is concerned.
There are many ways to accomplish this, here is one option: ( http://www.jcrocket.com/tttjig.shtml )

Keep up everything that your doing here and when your ready we'll get together and review and sign off on your packages before the actual flight.
Title: Re: BB Level 3 project
Post by: RickB on January 14, 2016, 11:48:54 AM
Really nice build! what 3d printer are you using?

Robo 3D R1+. (http://www.robo3d.com (http://www.robo3d.com))

Not to derail, but what are you're impressions of it?  I've been toying with the idea of getting one myself.  There are bunch of parts for various scale projects that I want to build that it would be really handy for, especially with the largish build volume compared to a lot of the other small printers.
Title: Re: BB Level 3 project
Post by: David Carter on January 14, 2016, 01:46:40 PM
David so far so good on you L3 build and this is a perfect way for me to review everything so I can sign off on the project when the time comes. I noted that you said you were using a nylon strap on the motor mount. This would be fine as all "M" motors don't have an ejection charge that could damage it, but some 54 motors do. So you would need to be careful using those.

Although from the pictures you post here that strap actually looks like a Kevlar strap, which is what I would have recommended and is better suited to withstanding powder burns.

One thing you might want to consider for your build is a tip to tip fiberglass application to beef up the fins to stand up to the G-forces a "M" motor will put the airframe through, especially where fin flutter is concerned.
There are many ways to accomplish this, here is one option: ( http://www.jcrocket.com/tttjig.shtml )

Keep up everything that your doing here and when your ready we'll get together and review and sign off on your packages before the actual flight.

Mike, you're right about the Kevlar. I had to review what I ordered to verify :)

I've used plugged motors before. The delay times available were too low for my rocket so I had to rely on the electronics.

I must confess, I hadn't considered reinforcement beyond good solid fillets. I guess I figured 3/16" fiberglass would be enough. I've found a few calculators for fin flutter, but I can't access them from work so I have to wait until this evening. From what I can gather doing the reading though, if the fin is shaped correctly you shouldn't get much flutter. Reinforcing fiberglass with fiberglass is just using a thicker fin isn't it?

I guess that's why I got into this... to learn things  :)
Title: Re: BB Level 3 project
Post by: David Carter on January 14, 2016, 01:52:55 PM
Really nice build! what 3d printer are you using?

Robo 3D R1+. (http://www.robo3d.com (http://www.robo3d.com))

Not to derail, but what are you're impressions of it?  I've been toying with the idea of getting one myself.  There are bunch of parts for various scale projects that I want to build that it would be really handy for, especially with the largish build volume compared to a lot of the other small printers.

I really like it. I took it out of the box and was printing in minutes. Some printers require a lot of DIY to get up and running, but this was pretty much plug and play.

I printed a few things, left the country for a couple of months, and when I came back and printed some more without issue. It was printing pretty much non-stop for about a week and a half doing prototypes and builds. I love it. There are contract services that will print for you using your model files, but if you require a series of prototypes then nothing beats having your own.

That being said, last night I seem to have gotten a clogged nozzle. I went to bed. I'll let you know how easy it was to clear that, but I can't imagine it being any worse than any other printer. Their online help is quite good, and by all reports so is their phone support. I have no first hand knowledge of that. Other companies though are notoriously bad about after sales support.
Title: Re: BB Level 3 project
Post by: RickB on January 14, 2016, 04:01:01 PM
Good to know, thanks for the info.  What are you using to generate the print files?  I can export to .stl from NX, which I use at work.  I also just discovered that Rocksim exports to .stl, but I'm not exactly sure what you'd get as a result...
Title: Re: BB Level 3 project
Post by: David Carter on January 14, 2016, 04:23:14 PM
Good to know, thanks for the info.  What are you using to generate the print files?  I can export to .stl from NX, which I use at work.  I also just discovered that Rocksim exports to .stl, but I'm not exactly sure what you'd get as a result...

Using FreeCAD. It's open source and cross platform, which is important to me. But it's got some really annoying bugs you need to learn how to work around and takes some time to learn how to use it effectively.

There are a number of online and cloud based options out there, but a lot of the time I'm offline or on an unreliable connection so they aren't good options for me. Cross platform was also a concern as I travel with a Mac but have a PC desktop at home.

In particular, one of the cloud based options that looked pretty good, and would probably give you fewer headaches than FreeCAD, is http://www.autodesk.com/products/fusion-360/overview (http://www.autodesk.com/products/fusion-360/overview)


Here's a good guide to modeling software: https://www.gliffy.com/go/publish/5271448 (https://www.gliffy.com/go/publish/5271448)

I've got an article coming up in the PSC newsletter that gives a pretty full write up on the options. I don't want to post it here because it's not published yet, but I can send it in an PM if you're impatient.
Title: Re: BB Level 3 project
Post by: mdutch on January 14, 2016, 05:58:57 PM

 Reinforcing fiberglass with fiberglass is just using a thicker fin isn't it?

I guess that's why I got into this... to learn things  :)

Dave, you should look over and read the link I gave you. By going from tip over to the next tip with fiberglass cloth especially if you use carbon fiber too gives you a stronger web over the whole section not just the fin to body connection point. I've seen this process done on a minimum  diameter 4" airframe using a 98mm "N" motor  and have the fins come back attached with no damage.
Seriously look at how it's done I'm sure you'll see the value in doing it.
Title: Re: BB Level 3 project
Post by: David Carter on January 14, 2016, 08:56:39 PM
Dave, you should look over and read the link I gave you. By going from tip over to the next tip with fiberglass cloth especially if you use carbon fiber too gives you a stronger web over the whole section not just the fin to body connection point. I've seen this process done on a minimum  diameter 4" airframe using a 98mm "N" motor  and have the fins come back attached with no damage.
Seriously look at how it's done I'm sure you'll see the value in doing it.

This seems like overkill to me. Having done the calcs, I'm nowhere near the flutter threshold for my fins. And in terms of strength, it even says in the article that it generally isn't required for G10 fins. I can see this being of great value for surface mount minimum diameter, but I've essentially got reinforcement on 3 surfaces with the through the wall fin design. It's not something I've seen done in similar level 3 projects either (admittedly I haven't seen many), except where they had non-fiberglass materials.

My reluctance is simply that this is a significant amount of work if it's not necessary, not just on the rocket but the tooling as well. I've not done any fiberglass work before so in my mind this adds another element of risk. I respect your opinion, and if you really think it's needed I will, but are you sure this is necessary?
Title: Re: BB Level 3 project
Post by: mdutch on January 15, 2016, 08:41:26 AM
Dave,
As your L3CC I'm not going to tell you that you have to do things one way or another. My job is to review what you present to me with your project to make sure you are building everything properly, and if I see a possible issue I will make recommendations to help you as I can.

Right now based on Img0836 and Img0837 you do not have enough epoxy reinforcement on your internal or external fin to airframe connections. If you have not installed your final centering ring or your Aeropac retainer yet, you can still do something about that. I would also appreciate a final description on what you did to improve that along with follow up photos showing what you did.

I'm not saying that you must do a tip to tip fiber glassing, but it is something that can be done after the motor mount, fin assemble is completed to beef things up if necessary.

Please remember I'm trying to help you succeed in achieving your Level 3 and help you learn something as well.

If you lose a fin during your flight you will fail the cert attempt. And with 95% of the fin out side of the airframe you WILL have fin flutter, (something you will see with your rearward facing camera).
Title: Re: BB Level 3 project
Post by: David Carter on January 15, 2016, 10:23:44 AM
Dave,
As your L3CC I'm not going to tell you that you have to do things one way or another. My job is to review what you present to me with your project to make sure you are building everything properly, and if I see a possible issue I will make recommendations to help you as I can.

Right now based on Img0836 and Img0837 you do not have enough epoxy reinforcement on your internal or external fin to airframe connections. If you have not installed your final centering ring or your Aeropac retainer yet, you can still do something about that. I would also appreciate a final description on what you did to improve that along with follow up photos showing what you did.

I'm not saying that you must do a tip to tip fiber glassing, but it is something that can be done after the motor mount, fin assemble is completed to beef things up if necessary.

Please remember I'm trying to help you succeed in achieving your Level 3 and help you learn something as well.

If you lose a fin during your flight you will fail the cert attempt. And with 95% of the fin out side of the airframe you WILL have fin flutter, (something you will see with your rearward facing camera).

I definitely don't have enough reinforcement yet... that's just begun. :)

While I may challenge your recommendations, that doesn't mean I'm not listening. You definitely have more experience in this than I do so I take your advice seriously. Looks like I'm about to build a glassing jig!
Title: Re: BB Level 3 project
Post by: mdutch on January 15, 2016, 11:14:41 AM
Why don't you do your reinforcing first and we'll go from there before you build a jig.

Here, let me make a point based on my experience; I have two Wildman Eagle Claw rockets in my fleet. One is stock with the 54mm motor mount, the other was modified with a new tail cone and a 75mm motor mount. Neither rocket has 'TtT' reinforcing, yet.

I have flown the modified Eagle Claw twice with a 2 grain and 3 grain research motor respectively, with no issue with the fins. But then it hasn't flown on a 'M' yet either. I have also flown the stock version several times and a few times on a L1300BB by AMW, (a very hard hitting motor), And I did lose one of the large fins once, though that might have been due to a hard landing.

On the modified Eagle Claw I did fill the inner cavity by each side of the fins with about a 1/2" of epoxy. I also have a decent fillet on the exterior of the airframe at the fins. Some day I will fly the rocket on a "M" motor, but I'm also sure that I will be doing a 'TtT' application before then.

Based on this and a few other L3 cert attempts I've witnessed I'm sure you can see I'm trying to help you succeed. Again for now, finish beefing up your attachment points and we'll go from there.
Title: Re: BB Level 3 project
Post by: David Carter on January 17, 2016, 03:38:18 PM
Well, since it seems important, I've decided to post my fin flutter calcs. Not just to satisfy Dutch, although that's important too, but to satisfy myself. Feel free to review and comment. Also, if you use a different method for fin flutter calcs, then by all means let me know.

I based my analysis on the contents of this article https://www.apogeerockets.com/education/downloads/Newsletter291.pdf (https://www.apogeerockets.com/education/downloads/Newsletter291.pdf)

I've attached the spreadsheet I used with my calculations. With the expected maximum speed (from rocksim) I have a 47% safety margin using G10 fins

I've also found some other spreadsheets that claim an even higher error margin, but they come with no explanation of their calcs. One claims I can go to Mach 10! I decided not to use that one...
Title: Re: BB Level 3 project
Post by: David Carter on January 24, 2016, 02:25:06 PM
Well, I've been kind of quiet this week. Dealing with a clogged extruder in my 3D printer... a common thing but my first so it's a learning curve. In the meantime I've been receiving parts... ejection charge canisters, eyebolts, all threads, teathers, and more.

I also have my main recovery chute. It's a SkyAngle Cert-3 XL, which should bring this to a soft 17 fps landing. Unfortunately this required a change in my design. The original design had a forward airframe that was 24". However, when packed for a 4" airframe it requires 25". So I also received my new 36" fibreglass tube. I've tried to pack a chute into too small a space before and it's not fun (I also got a new forward airframe for that rocket. Ain't got time for that sh*t!)

So no assembly last week, and probably not the week coming up... but more to follow!

In the meantime feel free to review the flutter calcs from my last post.
Title: Re: BB Level 3 project
Post by: RKeller on January 24, 2016, 05:42:09 PM
I've been using Aero FinSim for flutter analysis. http://www.aerorocket.com/finsim.html (http://www.aerorocket.com/finsim.html) There used to be a download link but I think you have to email and ask for it now. I plugged in your design and came up with slightly lower numbers, but over 1300fps for flutter velocity and 1700fps for divergence velocity. FinSim is known to be conservative.
Title: Re: BB Level 3 project
Post by: David Carter on January 28, 2016, 06:32:47 PM
Really nice build! what 3d printer are you using?

Robo 3D R1+. (http://www.robo3d.com (http://www.robo3d.com))

Not to derail, but what are you're impressions of it?  I've been toying with the idea of getting one myself.  There are bunch of parts for various scale projects that I want to build that it would be really handy for, especially with the largish build volume compared to a lot of the other small printers.

I really like it. I took it out of the box and was printing in minutes. Some printers require a lot of DIY to get up and running, but this was pretty much plug and play.

I printed a few things, left the country for a couple of months, and when I came back and printed some more without issue. It was printing pretty much non-stop for about a week and a half doing prototypes and builds. I love it. There are contract services that will print for you using your model files, but if you require a series of prototypes then nothing beats having your own.

That being said, last night I seem to have gotten a clogged nozzle. I went to bed. I'll let you know how easy it was to clear that, but I can't imagine it being any worse than any other printer. Their online help is quite good, and by all reports so is their phone support. I have no first hand knowledge of that. Other companies though are notoriously bad about after sales support.

As I mentioned earlier, the article I wrote about 3D printing for PSC is now available online at http://www.psc473.org/Newsletters/Issue185.pdf (http://www.psc473.org/Newsletters/Issue185.pdf). I wrote this a couple of months ago.

I'm still dealing with my clogged nozzle. Apparently the print head I received (referred to as the hot end) was not the latest design. Clogs and jams are not uncommon, but none of the standard fixes seemed to work for me. I have a free replacement on the way as we speak (under warrenty) and I spent the $40 for a spare just in case.

There are some ways to minimize these issues, including oiling the filament with canola oil. I'll be printing an oiler as soon as my replacement hot end arrives.
Title: Re: BB Level 3 project
Post by: David Carter on February 25, 2016, 12:22:29 PM
Signs you are deep into a build: boxes for wood and tools for a tip to tip jig, laminating epoxy, fibreglass, carbon fiber, and various other materials filling the living room.

I took a break for some work travel but should be back at it this weekend  :)
Title: Re: BB Level 3 project
Post by: mdutch on February 25, 2016, 12:41:08 PM
Looking forward to seeing you continue on your L3 project Dave.  :D
Title: Re: BB Level 3 project
Post by: David Carter on February 28, 2016, 11:55:20 PM
A few things going on this weekend, including starting the tip to tip jig, but I'll share more about that later.

Since I'd never done any fiberglassing before, I thought I should practice. The rocket is 3 finned, but 4 were made, so I had one I could practice with. I also had an old cardboard tube. So I added a layer of glass to the tube and glued the fin onto it.

The technique I used is based on the tree layer method shown here, with each layer being a slightly larger piece of material. https://www.youtube.com/watch?v=PtYYsX3VEmc (https://www.youtube.com/watch?v=PtYYsX3VEmc)

So each layer is in fact two, one of carbon fiber, and one of fiberglass. Prep time is far more significant than I expected. It was about three hours before I started mixing the epoxy. I made a lot of little mistakes, but that of course is the point of practicing. I also learned the value of making a jig!

There's a lot to be done still... the internal fillets, making the tip to tip jig, and of course the tip to tip reinforcement.
Title: Re: BB Level 3 project
Post by: David Carter on February 28, 2016, 11:56:54 PM
And some more...
Title: Re: BB Level 3 project
Post by: David Carter on March 23, 2016, 11:15:50 PM
Continuing the build... back to the internal fillets.

This has been the biggest thorn in my side in quite a while. I've alternately called this phase "Murphy's Law of Epoxy", "Why do I enjoy rocketry again?", and at many points just "F***! F***! F***!" The basic problem is that there's not a lot of room when you have a 75mm motor in a 98mm (4") tube. It sounds like more room than it is, especially with fat fingers like mine.

My first approach was to use RocketPoxy straight up. It flows albeit slowly, but not in my case. It just clumped up near the top of the tube. So I tried thinning it. And then some more. It did flow, just everywhere but where I wanted it. Eventually, I got it thin enough that I was able to inject it with a syringe. I placed a modeling clay dam over the end, and was able to get it to where I wanted it, albeit with quite a bit of colourful language.

I've done a lot of bad fillets in the past, but these are by far my ugliest.

This has definitely convinced me that tip to tip glassing is required, but also to use expanding foam in the fin can. So next up is the tip to tip reinforcement, then I'll put the rail buttons in place, fill the can with X-30 foam, and finally put the rear centering ring in place.
Title: Re: BB Level 3 project
Post by: David Carter on March 23, 2016, 11:20:04 PM
In the meantime, I've been working on my tip to tip jig. Absent a lot of wood working tools, this involved a bigger shopping spree than I wanted, but that's rocketry right? It's not pretty (I really hope any self respecting shop teacher would give it a failing grade), but it will do what I want.

I think this was as much work as the fin can so far!

I really shouldn't be allowed near a router.
Title: Re: BB Level 3 project
Post by: David Carter on March 25, 2016, 10:02:34 AM
And the first one is complete! In dire need of sanding though...

So that's three layers each of 5.7 oz carbon fiber and 3 oz fiberglass.
Title: Re: BB Level 3 project
Post by: David Carter on March 26, 2016, 10:38:04 AM
Tip to tip reinforcement complete. Sanding, expanding foam, etc... will have to wait until I return from my 5 week work trip. I won't get to fly ANYTHING until URRF. Le sigh.
Title: Re: BB Level 3 project
Post by: RKeller on March 26, 2016, 02:10:14 PM
looks really good David, glad you'll be back in time for URRF! I need to get that featured flights page up and running. this should go on there.
Title: Re: BB Level 3 project
Post by: Larry Weibert on May 18, 2016, 10:39:44 PM
Nice project Dave love to see that flight. I need to retire and free up some time.
Title: Re: BB Level 3 project
Post by: David Carter on May 20, 2016, 08:09:36 AM
Nice project Dave love to see that flight. I need to retire and free up some time.

Retirement would help with the free time, but I need to work to afford all of this!  :D

True to signature line, my last all too brief visit home was spent sanding. Progress is being made, but I'm in a tedious phase. Currently on another work trip but I hope to get the airframe finished the first week of June. I may be flying without a paint job though. Final touches may not happen until the week before. Good thing I started this months in advance! Le sigh
Title: Re: BB Level 3 project
Post by: David Carter on June 02, 2016, 07:35:25 PM
It's been a while, so an update is in order. I've been traveling for 8 of the last 10 weeks, and I leave in 3 days for another 2 weeks. (A trip that wasn't supposed to happen. Ask me how happy I am about that!) So time to get it all done is tight.

First, it's unlikely I'll get the camera mount done. My 3D printer is having some issues and I have no time to debug it. I also refuse to deface my rocket  with the aesthetically and aerodynamically awful camera shroud that is commonly used. I can do better and I will on a future flight.

So, my goal before leaving again is to complete the airframe and have it ready for finishing. At this point, that means Bondo and sanding. Lots of sanding. I believe my signature says "90% of rocketry is sanding?". These next three days won't change that opinion. I also intend to have the mounts for the rail buttons in place, the aft centering ring glued in, and the motor retainer attached. This will allow me to do the painting.

I will not be using the expanding foam in the fin can. I think the internal fillets and the tip to tip reinforcement are sufficient for the job, and they've added a lot of tail weight. I think the foam would just be overkill and ballast I don't need. My CG is still fine (and I have the sims to prove it), and I don't want to mess with that at this point.

Still to come, the ebay, recovery rigging, ejection testing, finishing. Sorry Dutch but it may be a last minute documentation update!
Title: Re: BB Level 3 project
Post by: David Carter on June 05, 2016, 02:44:54 AM
Well, that's been a busy three days!

Fin can filled and sanded. No more sanding until after primer is applied  :)

With that done, I was able to install rail buttons. As per Dutch's suggestion, 3 instead of 2. And with the rear one in place, I was finally able to put the rear centering ring on.

Some JB Weld, and the retainer is in place. It looks good with the transition!
Title: Re: BB Level 3 project
Post by: David Carter on June 05, 2016, 02:48:13 AM
But that's not all...

I started in on the ebay in earnest. The switch band had holes made for the two switches. Each switch had a 1/2" hole in the coupler, and a 5/8" hole in the switch band to give it that nice recessed look.
Title: Re: BB Level 3 project
Post by: David Carter on June 05, 2016, 02:52:17 AM
End caps were marked and drilled. Ejection canisters and U bolts were epoxied into place.

I still need to wire the electrical harness, including the terminal blocks that will connection the igniters to the electronics. That will have to wait until I come back. There are still some holes in the end block where the terminal blocks go and where an eye bolt could go. These will be filled in with epoxy later to prevent gases from leaking into the ebay.
Title: Re: BB Level 3 project
Post by: David Carter on June 05, 2016, 02:58:15 AM
Finally, holes were drilled. Lots of holes. The lower airframe will use shear pins to prevent drag separation (that's a lot of weight!) so those were drilled and tapped. Same for where the upper airframe connects to the nose. 3 x 3/16" vent holes were drilled around the switch band, as well as pressure vents for both the upper and lower airframe. And holes were made for the rivets that will attach the upper airframe to the ebay.

It's starting to look like a rocket!

When I get back, I'll wire up the electronics, add the "laundry", do my ejection tests, prime, paint, and document. Oh yeah, and fly! Is it URRF time yet?  :D
Title: Re: BB Level 3 project
Post by: RKeller on June 05, 2016, 08:35:11 AM
lookin good David!
Title: Re: BB Level 3 project
Post by: mdutch on June 05, 2016, 11:24:08 AM
Dave I like everything I see here, good work.
Title: Re: BB Level 3 project
Post by: David Carter on June 18, 2016, 12:49:29 PM
One week! Aaarrrgggghhh!

My plan was to finish the wiring and do the ejection tests before painting, but I have perfect painting weather today and tomorrow so plans change.

I finally attached the U bolt and end cap to the nose cone. I'd been holding off in case I needed nose weight, but even with the heaviest 75mm motors I still have a good safety margin. So on it goes. I used Fix-It epoxy putty to build a shoulder, and then reinforced on the other side with 5 minute epoxy.

So a little sanding, and a little priming, and it begins. These saw horses have a spot for 2x4s to make a work table, but with a little PVC piping it makes a great painting station. I should have the basic colours on by end of day tomorrow. Fancy details will have to be post maiden flight.
Title: Re: BB Level 3 project
Post by: David Carter on June 19, 2016, 08:31:21 PM
Shouldn't have any problems spotting this on the launch pad! A field maybe, but that's what the multi-coloured parachute and GPS tracker are for :)
Title: Re: BB Level 3 project
Post by: David Carter on June 26, 2016, 10:52:27 PM
I've a few details to add before I wind up this thread, but I'll break the suspense. Successfully flew for my Level 3 today!

Speed: 387 m/s, or Mach 1.13!
Altitude: 4696 m or 15407 feet or 2.92 miles!

Both exceeded the sim predictions (which typically overestimate), but not the waiver so I'll take it. These are also personal altitude and speed records :)
Title: Re: BB Level 3 project
Post by: mdutch on June 27, 2016, 09:13:07 AM
Great level 3 certification flight David, of course it wouldn't have gone so well if I had let you put it on the rail the way you started doing it.
And yes, I did make him kiss it goodbye too, probably why it was such a great flight.
Title: Re: BB Level 3 project
Post by: RKeller on June 27, 2016, 07:01:58 PM
That was an awesome flight! Congratulations!
Title: Re: BB Level 3 project
Post by: David Carter on June 28, 2016, 10:18:17 AM
Great level 3 certification flight David, of course it wouldn't have gone so well if I had let you put it on the rail the way you started doing it.

I still say I would have figured it out eventually, and it would have made for an awesome photo :)
Title: Re: BB Level 3 project
Post by: David Carter on June 28, 2016, 10:31:43 AM
One of the issues I had to fix when I got to the field was my altimeter. The Pico AA2 I had as my secondary wasn't beeping. So off to the Wildman trailer to see what he had. I got a Featherweight Raven as my replacement. Nice little piece of kit but it had some issues I had to deal with.

First was the physical mounting. Not only were the screw holes in different places, but they were also much smaller. My sled was designed specifically for the altimeters I'd originally intended to use, not this. Drilling holed would have meant having the back end of the bolts in my battery compartment. So, in one of the inserts I added some epoxy and glued the screw in place. I could always dremel it out later. To stop the altimeter from spinning on the single screw, I used CA to tack the bottom in place against the bottom post (epoxy doesn't bond well with the PLA plastic) This picture was taken post flight, so it held together quite well. All altimeters fired as designed and recovery was a success.
Title: Re: BB Level 3 project
Post by: David Carter on June 28, 2016, 10:36:50 AM
The flight was flawless. It landed right next to the road near the bridge, so recovery was easy. Performance was better than sim, but still within the waiver. It's a good thing it had the GPS though, because none of us saw it land.

My first supersonic flight (Mach 1.2), and a personal altitude record, just shy of both 5 km and 3 miles :)