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An often overlooked factor with cat is even if it was proven the cat was alive before impact and dead shortly after, the transgressors would only be 1/9th liable.
Click to expand...

Indeed. Until Shroedinger observed the cat, its destiny was undefined. Who killed Schroedinger's cat??? Its owner?


Back to rockets. This is why I love denatured alcohol (DA). The middle CR with fin slots was sadly sloppy, about 0.015" movement when square. It could make a 20 degree angle. After gluing the forward CR on the MM, I put JB Weld dots every 90 degrees, slid the the MM in the BT and inserted the fins. The rear CR was inserted and the JB Weld left to cure for a day, aligning the middle CR.

After curing I pulled the MM out and strengthened the joint. Fillett a la CJ pulled with 1/4" drip system tube.

DSC_6859.jpg
DSC_6589.jpg

No masking; it's not visible when built. If you ask how the fins will fit, you're right. DA is my friend.

DSC_6593.jpg

About 3 hours into the cure, I used a toothpick to remove most of the epoxy where the fins will mount. The gaps were cleared with a paper towel soaked with DA wrapped around the toothpick. There's nothing to sand. JB Weld is under the CR at the fin joint, but isn't on the MMBT or CR in a place that interferes with the fin.

I don't like sanding. I use DA as 50,000 grit sandpaper whenever the situation allows.
 
Rockethound said:
You have an umlaut, good for you. I agree, from the time the rocket should have impacted the ground until the time Herr Schrödinger observed the cat, the cat was in a superimposed state of 99.99999% alive and 0.00001% dead. To be honest, I have never understood why the cat's consciousness didn't collapse the wave equation, but for now it seems you have to be human or degreed to do so.


For each motor in the database, there are data points unique to the motor (e.g. thrust curve) and data points that related to other motors (e.g. 29mm vs. 38mm). The latter are "relational" fields, thus "relational database". Some of the fields in a motor's database entry are unique to the motor.

At first I suggested each motor have a field for NOTAMs (for lack of defined word). When I later said "N fields", the idea was there would (for each motor) be a NOTAM field for NAR, TRA, CAR and other agencies ("N agencies"). This lets each agency state or not state an opinion on a motor, and the user could see all of them to decide for hirself. This leaves no room for preference, rather, it leaves room for a difference of opinion. Each agency is not bound by any others' decisions, but each agency can remark if they wish.

Thinking about what I wrote, this implies the automatically generated notification to a manufacturer should be also be sent to all participating agencies, or they're behind the power curve. This is where we get to what you talked about, the "hard problem" of de-cert or issuing a warning. In this scheme, TRA would know if NAR dissed a motor, and then could take any action it deemed appropriate - which includes no action. By having "N fields", the decision not-to-decide is clear, giving the user a bit of thinking space.


Thank you for your respect of a complete rookie. This hobby is full of gentlemen.
Click to expand...

Each motor is certified by one of three different certification authorities in North America. All three of us agree to recognize and accept certifications done by either of the other two. In order to abide by this agreement it’s generally understood that only the organization which certified a motor can revoke that certification. It’s extremely unusual to revoke a certification anyway, but all three of our organizations bend over backwards to play well with each other. It’s a small pond but no room for small personalities.
Typically there will only be thrust curve data from the one certifying authority until users submit data to ThrustCurve. But the certifying authorities test multiple motors depending on the impulse. So there could be five different samples from NAR for a C6-5. In fact, counting previous certifications for that motor (certifications are supposed to be good for a few years, then redone) there could be quite a few.
All actions motors (including all notices to manufacturers) are sent to a distribution list that includes all three organizations. That also results in the motor being updated on the one official combined list which is published on the NAR website.
Of course from time to time things need to be reviewed to see what’s working and what can be improved. That’s why our meeting in April is happening.
Guten Abend.
 
Steve, these are wonderful details to share with people. Knowing what goes on behind the scenes makes us wiser, and reassures us that good people are watching out for the safety of everyone at a launch. There were 20+ children at Snow Ranch; what you do is so important! Sehr gut und vielen Dank, mein Freund. Wenn Sie moechten, koennen wir PM uber dies.

Gruss Gott...
 
Uh... friends, due to my job I email in Dutch and German 5-10+ times a day. It feels natural to me, but I suppose you are wondering what's happening. But no hidden messages, just enjoying the use of another language. It's so common in Europe, and so unknown in America. You can use translate.google.com but a lot of the sentences sound similar to English.

"Halte den Daumen", though... it's "hold the thumb" literally but we say "cross your fingers". I said "Keep it simple, then cross your fingers" and in German there was a word play on the verb halten.

When I post this, look at my avatar. It may/will change in the future, but for now it is the TR-08 - the maglev train Trans Rapid - 08. A customer from Weesp, NL, is a track design engineer for NS (Nederlandse Spoorwegen, the Dutch State Railroad). He got us an engineering test ride on the TR-08 in 2002. The speed 401 kph at the bottom was taken while I was a passenger. The photo of the TR-08 going around the curve was with Hans after our ride.

Guess what? This is very weird, but when TR-08 was to depart, we felt a 50Hz hum (51.3 Hz, so it didn't interfere with the electrical grid). There was a barely perceptible sway, then it started moving forward. At no time from 0 -> 401 kph did the sound change. There was a gentle whish at the window joint, very subdued, and the ever-present, ever-so-gentle 51.3Hz hum.

Horizontal rocket science. A reason for the curious avatar.
 
Rockethound said:
Herr VonRektofen,

Lies diesen Thread ... die DX3 ist sehr komplex. Behalte es einfach, dann halte den Daumen.

Schoenen guten Abend,

Steinhund
Click to expand...

Wie Gehts, Steinhund,
Ja, ich werde den Thread lesen...
Ist etwas einfacher einzurichten als das DX3?

Vielen Danke!
Tchuss!
Franz in NJ
 
Wie Gehts, Steinhund,
Ja, ich werde den Thread lesen...
Ist etwas einfacher einzurichten als das DX3?
Click to expand...

Es geht gut, danke.

I started looking for L1 rockets at Madcow, and there is a thread by Caley about her efforts to build a DD DX3. As I learned in this thread, a lot of factors enter into the L1 choice. I liked the NASA-style drouge/main deployment and was aiming at all DD rockets, the DX3 and Tomach among them and the Blackhawk 38 very near the top.

If you build a DX3 single deployment, it won't involve much more complexity than the Smoke I'm building. If it's a 38mm body tube, you'll find yourself working in cramped quarters. Because of my 25+ years building FG and CFK R/C models, I felt well-equipped for a 38mm rocket.

Maybe I would have built it well, but I would not have finished it in a week for sure. With the Estes Nike Smoke Pro Series 3", I will be finished in a week (save painting). There's a lot of body tube to work in, which makes tasks we didn't encounter in R/C easier to manage, and gives me skills for a 38mm rocket. The fat body tube lets me use a Jolly Logic Chute Release (JLCR), which just barely fits in a 38mm and doesn't fit in some of them. With my fat rocket, packing is no issue and the JLCR could practically fit in sideways.

Then there is the "Where did it go?" issue. By building a short, fat, lightweight rocket (with lots of base drag, hehe), I can use a rewarding H motor and see the rocket the whole flight. If you build a 38mm DX3, to quote another TRF member: "Can you see a yardstick a mile away?" Do you really want to deal with tracking? Choices seem limited: a simple Tx and a Yagi array antenna to get an azimuth but no distance, or earn your tech level Ham license and use a GPS Tx that pinpoints its location (even as it drags across a field, as David McCann learned).

Why do all this complexity? Why build so many things that all have to work together on a cert flight? Please, start on page one here and see what happened to me. Black powder is no big deal to me, electronics are no issue, and perhaps because of my German ancestry, I enjoy complexity. But I'm building an Estes rocket, and you should read the joy that came from others when I accidentally found myself buying a Smoke. They knew what I now know: KISS principle, or "Build the dinghy first."

It may not sound like your style. It isn't my style. But I am very pleased with what I am doing. Today I'm going to build some carbon fiber braces into the body tube to strengthen it for the larger H motors. I have become proud of this cardboard Estes rocket - I'm building it my way, expressing myself. I hope you either have the build background for the DX3 and the electronics laying around, or you see the value of using a $50 kit, building it quickly and strong, getting your cert and moving on to the rockets that intrigue you. Surprisingly, I'll not build a Blackhawk 38 next as I assumed, but maybe a Darkstar 2.6. Heavy rockets let you watch them for a longer time.

And then there is the adrenaline rush of the H410 motor; the video is fun to see and shows why he fell in love in less than a second. But remember, he lost his rocket for that rush. For him, that trade was worthwhile. Express yourself.

Shoenen guten Tag!
 
Rockethound said:
[Much good reasoning snipped above and below...]
Choices seem limited: a simple Tx and a Yagi array antenna to get an azimuth but no distance, or earn your tech level Ham license and use a GPS Tx that pinpoints its location (even as it drags across a field, as David McCann learned).

...
Click to expand...

There are two middle grounds here. First the 900 mHz non-Ham GPS trackers. In the rocketry-specific versions, there are the Big Red Bee and Eggfinder products, both of which I've used with success. If you fly in an area with good cell reception, the second option is a wide variety of cell-based dog and [other stuff] trackers. There's lots of threads in the electronics subforum about tracker products.
 
By the way, SARG was rescheduled for the 31st, so you've got 9 days to get her together for a shakedown flight! :) Should be better weather that weekend as well... seeing 70 and sunny. light breeze.
 
I haven't weighed mine but the 26oz empty weight on your file seems a little pessimistic. I won't be able to weigh mine for another four days. Additionally, the launch lugs on your file show a .6" inside diameter and .67" outside diameter, which is too big and probably adding drag in the sim.
Click to expand...

FlyFalcons - thanks for noting the launch lugs. I'll fix them. You were right - now that the OR file is cleaned up, mass without motors is just 19oz.
 
Well, this is another fine mess I've gotten myself into.

CGissue.png

Stability 0.954 with all the laundry at the top of the BT. What will happen when 15-30G's hit it? It all moves down until it finds a reason to stop. If the real model turns out to have the CG computed here, maybe I'll use a couple pieces of Kevlar glued inside the BT in an X shape to keep things in place. The Nomex protector will slide onto the Y harness. After packing, wrap the Nomex around it all, including the last 8-12" of the Y harness. Stuff it in, let the Kevlar hold it all at the top of the stack.

Gluing the Kevlar to the CF rods will... oh, no, this isn't a good idea. The Kevlar will be pushed down, pulling the BT sides inward. Maybe an X of CF rod glued to the vertical CF rods that embed in the MM would be smarter. All this will help with the stability as well because most of it is forward of the CG.
 
Do you have CF rods inside it? The easiest way is to install a shelf. 1/8" plywood, cut a bulkhead to fit inside body. Drill ten 1/2" holes in it.

Measure how much room you will need for nose cone shoulder and all recovery gear. Glue it down that far in the tube. Notch for kevlar harness and rods if you have them.
 
I think most of the Nike designs are close to 1.00 Cal by default. You are right that you don't want a ton of mass sliding backwards down the tube though and shifting the CG. Also remember though that in the first 0.5 seconds most of that propellant weight out back will be "exhausted". :) The ideas you have are great for keeping things in place though, and if they don't pose too big of a building issue, might be worth investigation. here's my 4" Nike Smoke I'm actually building right now based on some Madcow raw materials. It is also right at one cal, but I simmed it with the laundry at it's lowest available point just to be sure.Capture4.jpg I've not had any issues BTW flying my stock PS-II Nike Smoke on hobbyline G's. I will admit to not loading up an H in it yet. Mine also weighs in at 19.1Oz... which is why I questioned your earlier number and height.
 
Rockethound said:
Well, this is another fine mess I've gotten myself into.

CGissue.png

Stability 0.954 with all the laundry at the top of the BT. What will happen when 15-30G's hit it? It all moves down until it finds a reason to stop. If the real model turns out to have the CG computed here, maybe I'll use a couple pieces of Kevlar glued inside the BT in an X shape to keep things in place. The Nomex protector will slide onto the Y harness. After packing, wrap the Nomex around it all, including the last 8-12" of the Y harness. Stuff it in, let the Kevlar hold it all at the top of the stack.

Gluing the Kevlar to the CF rods will... oh, no, this isn't a good idea. The Kevlar will be pushed down, pulling the BT sides inward. Maybe an X of CF rod glued to the vertical CF rods that embed in the MM would be smarter. All this will help with the stability as well because most of it is forward of the CG.
Click to expand...

Don’t worry about it until you build it. Then just see where the Cg is and add nose weight to compensate.
If you insist on a shelf for your chute build a baffle with a perforated bulkplate and mount it where you want the chute to rest. There are lots of articles about baffles here, but the main purpose is to prevent hot particles from the ejection charge from burning holes in your chute. The gases don’t do the damage; the hot sparks do. An extended motor tube that ends near the bulkplate and perforations in the bulkplate that are outside of the OD of the motor mount tube may be sufficient. Those hot particles will strike against the underside of the bulkplate and not fly through the holes. It can be fancier than that, but the idea is the same, no straight path for the hot sparks to travel.


Steve Shannon
 
Or, push all the recovery gear in the tube as far as it will go. And measure your CG again , then rerun your sims. Might not be bad to have your recovery gear far in the tube. And 1-2 caliber of dog barf will keep it forward some.
 
Eric said:
Or, push all the recovery gear in the tube as far as it will go. And measure your CG again , then rerun your sims. Might not be bad to have your recovery gear far in the tube. And 1-2 caliber of dog barf will keep it forward some.
Click to expand...

Yup, dog barf will keep your flight a bit lower too and make for a fantastic confetti shower to celebrate your successful L1. :) And Eric, I'm hoping there are no Carbon Fiber shover rods and dog barf my commuter jet! Now I'm suspicious...
And speaking of dog barf, I'll see you at lunch here in a bit, we can chat all things rockets.
 
Yes, See you in a little bit, and I keep the dog barf at the tool box so it won't end up in the plane.

If you ever need dog barf. I bought a bail and will never use it all. Free for the taking.
 
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The bulkhead came out nicely, with 12 half-inch holes. Turned out the CF rod was 2.5mm. It's fairly stiff on its own, and when bonded to the BT will resist flex as well as compression.

DSC_6596.jpg

I also made a rod positioning ring that will be glued on the top MM CR. I'll slide the MM in backwards, slide this onto it, then tack it in place with CA. This will align the rods at 90 degrees and flush to the BT. They'll be inserted when the MM is glued in, with an extra dab of epoxy on the tips. The goal is to have the rods directly over the fins, where the structure is quite strong.
 
I like to put a few less holes in my chute shelfs and put an eyebolt in them for a recovery anchor point.

Nice work by the way, having or having access to a lasercutter is a dream for me.
 
I like to put a few less holes in my chute shelfs and put an eyebolt in them for a recovery anchor point.
Click to expand...

Oh, that's a good idea. Thanks. An eyebolt above CG will raise the CG and get rid of the Y harness. Funny how things evolve.

These were cut on a 36x24 Full Spectrum Laser in my garage, typically used to make railroad components for customers. Comes in handy at other times, too.

Here's how the rod guide turned out with a sample CF rod.

DSC_6598.jpg
 
Rockethound said:
Es geht gut, danke.

I started looking for L1 rockets at Madcow, and there is a thread by Caley about her efforts to build a DD DX3. As I learned in this thread, a lot of factors enter into the L1 choice. I liked the NASA-style drouge/main deployment and was aiming at all DD rockets, the DX3 and Tomach among them and the Blackhawk 38 very near the top.

If you build a DX3 single deployment, it won't involve much more complexity than the Smoke I'm building. If it's a 38mm body tube, you'll find yourself working in cramped quarters. Because of my 25+ years building FG and CFK R/C models, I felt well-equipped for a 38mm rocket.

Maybe I would have built it well, but I would not have finished it in a week for sure. With the Estes Nike Smoke Pro Series 3", I will be finished in a week (save painting). There's a lot of body tube to work in, which makes tasks we didn't encounter in R/C easier to manage, and gives me skills for a 38mm rocket. The fat body tube lets me use a Jolly Logic Chute Release (JLCR), which just barely fits in a 38mm and doesn't fit in some of them. With my fat rocket, packing is no issue and the JLCR could practically fit in sideways.

Then there is the "Where did it go?" issue. By building a short, fat, lightweight rocket (with lots of base drag, hehe), I can use a rewarding H motor and see the rocket the whole flight. If you build a 38mm DX3, to quote another TRF member: "Can you see a yardstick a mile away?" Do you really want to deal with tracking? Choices seem limited: a simple Tx and a Yagi array antenna to get an azimuth but no distance, or earn your tech level Ham license and use a GPS Tx that pinpoints its location (even as it drags across a field, as David McCann learned).

Why do all this complexity? Why build so many things that all have to work together on a cert flight? Please, start on page one here and see what happened to me. Black powder is no big deal to me, electronics are no issue, and perhaps because of my German ancestry, I enjoy complexity. But I'm building an Estes rocket, and you should read the joy that came from others when I accidentally found myself buying a Smoke. They knew what I now know: KISS principle, or "Build the dinghy first."

It may not sound like your style. It isn't my style. But I am very pleased with what I am doing. Today I'm going to build some carbon fiber braces into the body tube to strengthen it for the larger H motors. I have become proud of this cardboard Estes rocket - I'm building it my way, expressing myself. I hope you either have the build background for the DX3 and the electronics laying around, or you see the value of using a $50 kit, building it quickly and strong, getting your cert and moving on to the rockets that intrigue you. Surprisingly, I'll not build a Blackhawk 38 next as I assumed, but maybe a Darkstar 2.6. Heavy rockets let you watch them for a longer time.

And then there is the adrenaline rush of the H410 motor; the video is fun to see and shows why he fell in love in less than a second. But remember, he lost his rocket for that rush. For him, that trade was worthwhile. Express yourself.

Shoenen guten Tag!
Click to expand...

Danke for all the info. and insight! Maybe I confused you a bit...I was originally asking if the Torrent kit that Madcow makes for Apogee Components differs much from the Super DX3 kit....They are both 4" diameter body tubes, plenty of room to work within, and I'm planning to build it with an essentially empty AV bay (except for a JL Alt3), and I also plan to run it single deploy with a drogue and a JLCR for the main...I think a 4" diameter cardboard/plywood finned spacecraft would allow me to be "low and slow" for my first attempt at L1.... Like yourself, I'm also coming back to Rocketry (after some 39 years) from RC Planes, Sailplanes, and RC Helis as well....I've built a lot of craft and I'm trying to plan this return to Rocketry to make the most use of my build time...Best wishes with the Nike Smoke, hope all goes well with your attempt, sounds like you have a greater understanding than I have at this point...
Cheers!
Franz in NJ
 
This is what Rich's thought inspired. The eyebolt, washer and nuts weighed 30g. This seemed out of line with the spirit of things. The baffle was only 6g. To make things worse, with the eyebolt in the middle, the stress is in the weakest part of the baffle. A new approach was needed.

DSC_6599.jpg

There are three 1/8" holes on each side. The Kevlar threads down the first, up the next, the down the last.

DSC_6602.jpg

On the back side, the tag ends tuck under the first loop on each side. A spot of JB Weld under the loops on top of the baffle, one under the tag ends and one under the loops that tighten the tags, and it's nailed in place with minimal weight. The stress is at the outside of the body tube, right by the CF rods. This will be strong and functional. Rich, there will be a Nomex spark protector around the laundry.

Edit: since I don't know where the baffle will mount, I don't know the best length for the Y harness... so the tag ends aren't cut.
 
Radian.jpg

Hey, SARG, that thing in the red circle is a Radian, not a rocket! Does that mean it's OK to bring a small (~14") red Pitts biplane to mess around with in mostly-horizontal airspace? Maybe another Radian??
 
I think the baffle being 10" down the tube would leave 8" for 25' of 1/8" kevlar, nomex and parachute wrapped in chute release, then nose cone shoulder. And if there is and extra inch or two. A little dog barf saves ware on kevlar and nomex.


There is a huge open field behind parking that wouldn't interfere with rocket business at all.
 
Last edited:
I think the baffle being 10" down the tube would leave 8" for 25' of 1/8" kevlar, nomex and parachute wrapped in chute release, then nose cone shoulder. And if there is and extra inch or two. A little dog barf saves ware on kevlar and nomex.
Click to expand...

That's a good recommendation, Eric. I put the baffle and support rods into OR and set the baffle at 10" with 1" of dog barf. So here's an odd sentence... could you please bring a bag of dog barf for me when we finally get to fly? Thanks!

The chute and hardware came yesterday. There's a 24" and 30" chute; the 30" brings it down at ~16 FPS and there's plenty of room for it in the BT. Quick links and swivels are nice... TFR is a good source. Shock cord is built. I think the innards are ready to go and it's time for primer.

The H115DM is a great choice, especially since we've had enough rain for the grass to be green at Snow Ranch.

G40-7: 1520' at 9.5G's (Estes recommended)
G80-7: 2010' at 13.4G's (Estes recommended)
H115DM: 2440' at 15.3G's
H135W: 2960' at 18.7G's
H53MY: 3180' at 9.6G's (best apogee at very low G's)

It takes 5g in the tip of the NC to bring the stability to a minimum of 1.0 cal for all but 3 of the motors. Those three are >0.98 cals. Still using by-piece data.

I have a question for people. I wanted the sim to reflect using the JLCR, so I put in a 1" drogue at ejection and the 30" chute at 500'. OR is telling me there will be 65G's when the chute opens. Does that make sense? With an 8" drogue there's no warning from OR. Does it need a drogue, or is drogueless safe for this setup?
 
OR likely isn’t accounting for the drag of the rocket as it tumbles. Just the weight on a 1”
chute. Unqualified guess, you’ll be fine drougeless and the rocket will fall on its side and spinning until the main goes.
 
Thanks, Dave. I have the drogue overridden to 0g so it doesn't mess up the rest of the sim. I have it at 8" for analysis, so I can see red warnings for real problems. If the drogue isn't present, every flight is red - I may overlook something.

First coat of primer on the BC; should be dry in a few minutes.
 

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