Level 3 Build Diary

[dixontj93060]

Well, the time has come. I will be building my Level 3 certification rocket. I will use this thread as a prompt and reminder to document the build process. Similar to my Level 2 build (unfortunately it looks like the rocketeer that hosted my L2 pictures took his site down), I will provide pictures (hosted on a major site like Flickr or Google), brief commentary and answer questions as I go. A couple of ground rules though before I begin:

1. I do welcome your commentary and input, but I do want to acknowledge the only real direction I feel obligated to respond to is from my Tripoli Level 3 TAP advisors, Rev. Brad Wilson and Bob Justus, both of which have reviewed the design for the past 30+ days.
2. Generally I take criticism well, but keep in mind, there are a million ways to build a rocket, and the path I have chose here is based on my collective experience. Let's all share and have fun--it's a hobby.
3. This is a working man's build. What do I mean by that? Not the "blue collar" connotation of working man, but the high time demand, fast paced, multi-tasking, executive. With the demands of my job and my family the posts will come in short bursts, be patient.
4. A corollary to #3 is that although I got straight-A's in Engineering and Physics, it has been 20+ years since I used any of it regularly. I still retain enough to be dangerous and play around for entertainment. I don't have the time to back everything up by pages of equations so I won't do so.
5. Another corollary to #3 is that this will be an extended thread. Given my time schedule, I expect this build to take 3+ months. Again, be patient, I will try to post consistently and be semi-efficient (I promise not to do a multi-page, open-the-package thread, ala Art Upton).
6. Finally, although I have a spacious workshop, I am not a craftsman. And even though, I do plan things out pretty well, I'm sure you will see a bit of trial and error along with a few gotcha's along the way. If you want to see a craftsman's build search "leegscott1" on this same forum.

I will have build pics up soon, but in the meantime, feel free to view the design section of my Level 3 documentation at: tinyurl.com/Level3Rocket (hope it doesn't put you to sleep ).

-Tim

 

[mIcahel]

If I can't agree to all of your ground rules and their coronaries, may I still
participate in your build thread? I have a particularly hard time being patient and can't make any promises there.

 

[UhClem]

I was scanning the design document and noticed that you misunderstand how the altimeters work.

Both the above controllers utilize accelerometers to measure orientation of their electronic board. Based on a tipping of the overall airframe of the rocket (with the controller in a fixed position within the rocket), the controller assumes that the rocket has achieved apogee and enables a signal on one of its channels.

Altimeters do not measure orientation. That requires a minimum of three gyros. What they do is integrate the acceleration to get velocity. When the velocity integral changes from positive to negative is when apogee detection occurs.

 

[stickershock23]

I did not read the part that tells what ALT he's using yet. but that is not ALWAYS true. Ever use a MAD? Magnetic apogee detector.. that is all it does, watches for the rocket to tip over.

Good luck with your LIII best advice I can give. take your time, it's not a race. and Keep it simple. Good luck, looking forwar to following the build

 

[dixontj93060]

mIcahel,

Hey, if you really knew me, you'd know most of what I said in my ground rules was in jest. Participate freely, act as you see fit.

Cheers,
Tim

If I can't agree to all of your ground rules and their coronaries, may I still
participate in your build thread? I have a particularly hard time being patient and can't make any promises there.

 

[dixontj93060]

David,

Hey, how are you!? Hope you and the guys in DARS have been able to get some good launches in this year!

Given your technical bent, I don't doubt your statement, and I'm sure there is a well-known aeronautical definition of orientation that involves three dimensional measurement/movement. But in looking up "orientation" in the dictionary there are a minimum of nine definitions (see attached) none of which mention gyros.

Yes, I do understand the measurements and the math, but you'll find I write in layman's terms (bad habit learned when moving from Engineering to Marketing) and I was using the general definition of orientation embodied in #2 below. Simply a change of direction--a rotation from pointing up to pointing horizontal in a simple two-dimensional plane describing the over "arching over" in the typical of the flight pattern of most rockets. Granted this flight pattern is not required for an accel-based altimeter to detect apogee, e.g., backsliding. So the description refers to the high-level system (rocket) transitioning through a nominal process (flight). Yes crude and non-rigorous, but I think it gets the point across.

BTW, I really need to get back down to Texas and fly a few!

-Tim

I was scanning the design document and noticed that you misunderstand how the altimeters work.



Altimeters do not measure orientation. That requires a minimum of three gyros. What they do is integrate the acceleration to get velocity. When the velocity integral changes from positive to negative is when apogee detection occurs.

 

[dixontj93060]

Mark,

No, Dave is technically right. I am using accel-based alts.

Hey, and you may not have put two-and-two together, but the best part of the build is when we get to YOUR STICKERS!

-Tim

I did not read the part that tells what ALT he's using yet. but that is not ALWAYS true. Ever use a MAD? Magnetic apogee detector.. that is all it does, watches for the rocket to tip over.

Good luck with your LIII best advice I can give. take your time, it's not a race. and Keep it simple. Good luck, looking forwar to following the build

 

[dixontj93060]

After answering Stickershock's post last night, I soberly considered just how far away we are from applying stickers. I had previously put together my build checklist and thought I'd share a current "snapshot" of it at: tinyurl.com/Level3BuildSteps if you want to view it and see the handful of things I have done so far (pics to be posted soon).

Of course one single step like laying up the fiberglass actually consists of a number of sometimes time consuming steps. For example, the other night it took me almost an hour just to build the mandrels for the end of the four BT sections and that is just prep for one step.

 

[kelltym88]

Yes, well welcome to high power. I have found that when trying save money by doing things myself, I actually spend much more time building, which, of course includes any/all prep work. But isn't that what makes projects like this so rewarding? I tell people that except for the body tubes, I built the entire rocket from scratch. I get a good feeling from that, especially when it flies right.

You should get much more satisfaction from this build by doing more of the work yourself. Keep us posted.


PS-- The rocket I was referring to is the one in my avatar.

 

[mIcahel]

Any reason you are using pyrodex instead of BP? I've used
both, but would choose BP for a cert flight unless it was
totally unavailable.

Noticed that you have a "break in" flight planned on an L.
I'm curious to understand the purpose or reasoning for a
break in flight. haven't searched the forum for an existing discussion
on this topic. Nice detailed documentation on your project.

 

[stickershock23]

Mark,

No, Dave is technically right. I am using accel-based alts.

Hey, and you may not have put two-and-two together, but the best part of the build is when we get to YOUR STICKERS!

-Tim

Cool, I am here when you are ready!

It was just a note about the Magnetic apogee detector. they are not really well known but they are pretty cool item, they work really well.

That is quite a long list of "stuff to do" It took me about 6 month of build time for my LIII (that does not include plan time) good luck!

 

[dixontj93060]

Yes, well welcome to high power..

Kekktym88, "...welcome to high power"?, are you sure you're responding to the right thread?

 

[dixontj93060]

I'm sure you have tons of customers and don't remember, but I actually already purchased them earlier this year.

Cool, I am here when you are ready!

 

[kelltym88]

Kekktym88, "...welcome to high power"?, are you sure you're responding to the right thread?

Perhaps I should have added a tongue in cheek to my comment. Obviously if you're working on a L3 project you have this type of experience. And who is Kekktym88? hahahaha

 

[dixontj93060]

Yeah, so maybe its welcome to high, high power or "really expensive" high power. ;-)

Perhaps I should have added a tongue in cheek to my comment. Obviously if you're working on a L3 project you have this type of experience. And who is Kekktym88? hahahaha

 

[quickburst]

Just curious. Why did you decide to use two accelerometer based Altimeters? Most L-3's that I have seen use a baro alt and an accel. altimeter.

I'm not commenting on or disagreeing with your decision. I feel like it's your project and you're decision. for instance I used two baro altimeters on my L-3, PerfectFlite MAWD and a PerfectFlite HA45. However, this was not the plan. I planned on using the MAWD alongside an ArtsII, however due to a situation beyond my control, my ARTSII was not available (believe it or not, I had left it home )

 

[dixontj93060]

mIcahel,

Good questions.

First on the BP. I live on the Indiana/Illinois border. You can purchase BP in Illinois, but have to have a registration card (don't remember the name of the card), but I cannot get one as my residence is actually in Indiana. All the "full service" gun shops in Indiana, at least the ones I know of within 50 miles don't carry BP because of the extra regulation, and from talking to the owners, I gather due to the cost of the licensing and insurance also. In any case, I have been using Triple 7 for some six year now. It works really well if prep'ed right. It does take some experience for sure, but I feel very comfortable with it.

(BTW, I'm surprised you or others didn't comment on using "homemade" e-matches. This is too could be considered a risk. On that subject, I have used this particular brand and build technique for years now--100s of e-matches with only one open and no in-flight failures, so I feel comfortable there also.)

Hmmm... The question on a break in flight is interesting... Not a real good answer on that one--maybe more philosophical. What I see is many people putting so much focus on the "real" flight event and then forgettting its a journey to enjoy. I intend to build and fly for the rest of my life and hopefully this rocket will have an extended life. It is built for, and meant to fly, over and over. The first flight and the certification flight are just two in a long series of experiences.

-Tim

Any reason you are using pyrodex instead of BP? I've used
both, but would choose BP for a cert flight unless it was
totally unavailable.

Noticed that you have a "break in" flight planned on an L.
I'm curious to understand the purpose or reasoning for a
break in flight. haven't searched the forum for an existing discussion
on this topic. Nice detailed documentation on your project.

 

[dixontj93060]

David,

Yes. Valid point. And I certainly could follow this path as I have multiple baro and accel-based altimeters. Here's my thinking/feeling...

Starting out early in my professional career as a reliability engineer taught the value of developing two or more independent event paths to really drive down the failure rate for the system as a whole. In addition, there is some value in using independent behavior/measurement/event triggering in each branch. This is especially true in the case of operation in a semi-chaotic, non-deterministic event like a rocket flight. And you are right, this independence in the avionics subsystem is achieved by many Level 3 flyers by using both baro and accel-based altimeters.

But, notwithstanding the above, there is even more value in having a lower failure rate / higher confidence in each branch. In other words, the more reliable each independent branch, the more reliable the whole system operation. Now, I don't want cause any issues with any altimeter manufacturers, but I personally have more confidence in the repeatability and consistency of accelerometer-based altimeters (although this is a gut-feeling thing as I have had good and bad experiences with both types). So given my higher confidence level and feeling of a lower failure rate for accel altimeters that is what I use. To achieve the desired independence in branch operation (behavior/measurement/triggering) I instead use altimeters from two different manufacturers. In this case Ozark and G-Wiz. Now, I don't know for a fact that they have different circuitry and algorithms (actually Dave Schultz who contributed to this thread earlier probably does). Instead this is just a high probability guess based on observing external behavior (for example, the ARTS2 in bench testing will show leakage current when testing trigger events with RLEDs, the LCX doesn't). During setup/configuration, I will also do other things to "force" independency, e.g., add a short delay on the apogee events for one of the altimeters.

So in short, I value the point of having differing circuits/software in each recovery event branch. I achieve this through utilizing differing manufacturer's, but prefer to use an accelerometer to measure apogee based on my perceived repeatability and consistency over baro-based measurement. Finally I feel this last point becomes even more pronounced when the rocket is being stressed past Mach, although this certainly isn't the case for this rocket in its first two flights.

-Tim

Just curious. Why did you decide to use two accelerometer based Altimeters? Most L-3's that I have seen use a baro alt and an accel. altimeter.

I'm not commenting on or disagreeing with your decision. I feel like it's your project and you're decision. for instance I used two baro altimeters on my L-3, PerfectFlite MAWD and a PerfectFlite HA45. However, this was not the plan. I planned on using the MAWD alongside an ArtsII, however due to a situation beyond my control, my ARTSII was not available (believe it or not, I had left it home )

 

[dixontj93060]

Kelltym88, Oh sorry. I was typing on my Blackberry and have fat fingers. /Tim

And who is Kekktym88? hahahaha

 

[dixontj93060]

For completeness, I suppose I should post the Rocksim file so here it is (along with the standard 2D view).

For the record, this certainly isn't a svelte rocket. Let's see, what would I call it, “flying pig”, “flying hippo”, no “flying tank”--Yeah that's it, a flying tank. Good looking tank though (at least in my opinion). The design document describes the sequence and events and desire to utilize a split fin design (which is one element and reason for adding to the weight). Yet there is kind of a “magic number” of 38 lbs (unloaded) for a rocket with a long, 75mm mount where you get access to 8 to 10 additional motors (across all manufacturers). I could get down to that weight and still have my split fin design and considered it by doing the following:

1. Removing one layer of fiberglass on the airframe
2. Using only essential all-thread (i.e., two pieces in avionics bay)
3. Removing two centering rings and a bulkplate
4. Utilizing Spherachute brand parachutes versus Rocketman Pro-EXP chutes
5. Removing all “precautionary” reinforcement (LOC Stiffy tubes, kevlar in spots, etc.)

In the end though, I decided to err on the side of over-design/build. First, it is my L3 flight and I do want to assure success. Second, I kind of like, low and slow, at least semi-slow for a cert flight. Third, I'm likely only flying Loki motors and they have enough “umph” to cover my needs and give me 3 to 4 reload choices depending on the configuration of the rocket. Finally I believe there will be enough time in the future to do finesse builds to provide the maximum range of motors, altitude performance, etc., so, this rocket will be built with precaution and thus to the "heavy" side.

View attachment Bruiser EXP3_v7_5.rkt

 

[patelldp]

I presume that you are using the split fin design for aesthetic purposes only? When I read that section in your report I got the feeling that you didn't want to cut entirely new fins, so you just added a forward set. In my mind, rather than doing all of that complex reinforcement work on the 1/8" G10 fins, wouldn't it be slightly more convenient to design a single set of fins to replace the originals? I am sure that you could sell the original Bruiser fins online to get some of your investment back, especially if they are G10.

Just my $0.02.

 

[dixontj93060]

Dan,

You are right that would likely have been a cheaper route and one of the options I was considering. The fin reinforcement needed to be done if I kept the G10--new fins out of a quality ply then probably no. Aesthetics was the primary vote to go split fin along with the need for a bit more weight in the back as it was fairly overstable fully loaded with camera and all.

-Tim

I presume that you are using the split fin design for aesthetic purposes only? When I read that section in your report I got the feeling that you didn't want to cut entirely new fins, so you just added a forward set. In my mind, rather than doing all of that complex reinforcement work on the 1/8" G10 fins, wouldn't it be slightly more convenient to design a single set of fins to replace the originals? I am sure that you could sell the original Bruiser fins online to get some of your investment back, especially if they are G10.

Just my $0.02.

 

[dixontj93060]

O.K. How about some build pics?

I'll try to keep these in chronological order following my build plan checklist as I take a few snapshots along the way.

First I guess was something I had my wife finish off about a month ago. I had won an RP auction over a year ago for some 4000 lb test, 1" TN. How about 80' of it:

My wife's part of the build project comes in with the sewing (loops, deployment bag, etc.) as she's an excellent seamstress and quilter. She did the loops using kevlar thread. Note the double bar and then double cross-box termination. She could tell you something about the size and spacing of the stitches for maximum strength based on the material and thread--but don't ask me. I figured the TN was rated high enough and the kevlar thread should be plenty strong/durable.

 

[dixontj93060]

Now on to the fins. If you read the design doc you know that the G10, even at 0.125 thickness was going to exhibit flutter with fins this size and of this geometry. So reinforcement was in order. I decided to build a laminate adding layers of 6 oz. glass and 1/16 aircraft ply to each side.

First prep'ing the fin core. I put 3/8" holes in the fiberglass in a random pattern (BTW, this is actually kind of hard to get a random pattern, i.e., no three holes aligning. I didn't want to create an area of weakness. In the end what I did was layout a very linear pattern of dots and then avoided them). This was done not to remove weight so much, but to provide more edges/bite for the epoxy (larger fore fins shown below).

Then I began alternating application of layers of aircraft ply and fiberglass to both sides (smaller aft fins shown below).

First set finished with top breather layer ready to be pressed.

 

[dixontj93060]

Now into the press. I have a client that does sublimation and they have this large 12'x6' press. I thought about doing the fins up there and putting them in his press, but then figured it was overkill. In the end I just bought a couple of pieces of the straightest shelving material I could find, cut it in half and used it as the press.

Then after six hours out of the press (larger fore fins shown):

Then trimmed up a bit (smaller aft fins shown):

So now--Wow are these fins substantial! All former flex in each of the individual materials are gone. Flat along all directions/dimensions, weight is consistent across all the fins within the size groupings and they mic out consistently at 0.31" thickness.

 

[dixontj93060]

Now on to the prep work for the body tubes.

I had cut a bunch of glass when doing the cuts for the fins.

Also some kevlar mat for reinforcement (I will also be using a more substantial kevlar weave later for spot reinforcement later in the project).

And then cut into strips for application at the ends of each body tube:

 

[dixontj93060]

Then peeling of the glassine layer (you may have noticed I have now moved down into my basement to get more room to work on the BT's. My son's skateboard ramps are in the background of some of these pics. But he's off to college now, so I have just that much more rocket build space ):

I cut my mandrels out of 8" concrete forms. Had to slice out 0.6 inches to get a good fit inside the body tube.

I don't know what you guys do, but I build/reinforce my mandrels with packing tape inside and out. It makes them hold form, but also provides adequate release from the epoxy after fiberglassing.

 

[dixontj93060]

O.K. set up and ready to go:

And yes, it will be a bit tough to work on that center BT, so I have another station set up for transferring/moving the appropriate outside section after completion.

More later!

 

[fox_racing_guy]

My wife's part of the build project comes in with the sewing (loops, deployment bag, etc.) as she's an excellent seamstress and quilter. She did the loops using kevlar thread. Note the double bar and then double cross-box termination. She could tell you something about the size and spacing of the stitches for maximum strength based on the material and thread--but don't ask me. I figured the TN was rated high enough and the kevlar thread should be plenty strong/durable.

Thats the absolute best amateur boxstiching I've ever seen, you wife should be very proud!

 

[leegscott]

Tim

Build is looking great!! On the fins, did you put a layer of cloth between the G10 and the plywood skins. Also do you have a weight yet for the fins (oz/sqin or similar ratio. On the loops, they look good. I have been taking my nylon to a shoe repair store for years and doing the same thing. About a year ago I had a testing lab pull a sample to failure and as best as I can remember it was around 1300lbs. Well good luck and keep the pictures coming!!