Documenting my Level3 and for sharing with my advisor.

[OverTheTop]

Hi Tim. Do your project as you want to do it, as long as it suits your L3 TAPs. People are variable, and so are TAPs. What one find acceptable another might not. You can either work with them or find alternates to sign off on your flight.

You remember well CJ! Correct on all counts.

DDT (Don't Debate This) was flown by Mike Passeretti and had a brazed aluminium fin can. It survived flying on an N5800.
https://www.rocketryforum.com/threa...ze-claimed-and-new-contest.63485/#post-676918
I was glad it worked as I was the one who suggested the brazing rods. I had used them on my 4WD sidesteps and they worked a treat.

You might be able to find more details of those on the Australian Rocketry Forum if the above post doesn't have enough info: https://forum.ausrocketry.com/index.php

Think things through and have fun .

 

[Ez2cDave]

Alumiweld brazing rods. Mike [if I remember correctly] pre heated the tube by placing on a grill and heating slowly to 400 degrees to prevent distorting tube while brazing the fins on...find his full up report in how to do it..Australian Forum...."Don't Debate This", as I previously mentioned. Full write up on how to do it and his testing method.

Is this the document ?

https://www.google.com/url?sa=t&rct...-pdf.279449/&usg=AOvVaw2pNBGe1ODnqRR8AiSImb0T

Dave F.

 

[OverTheTop]

Is this the document ?

That's one of the documents.

 

[blackjack2564]

winner..winner...chicken dinner! That be it.

 

[Ez2cDave]

winner..winner...chicken dinner! That be it.

Thank you , sir !

Dave F.

 

[TimothyG]

Got my wiring and switches and aluminum ordered today and drew up my sled and the first components to my fincan. Drawing for fincan only included cuts I'm going to have made on the CNC 3+1 mill at school so no forward or aft taper just facing and slots. I'm using slots to prevent me misalignment during brazing. I've had parts shift when soldering sights and it's aggravating to have to fight things straight again after solder is in the joint.
Gave up for the day on drawing the fins after having to fight solid-works rendering errors on planes I was trying to sketch in.


https://drive.google.com/drive/folders/1J2Upa-USW00c1wwOSrDDPrKWwbmahhyX?usp=sharing

 

[DRAGON64]

Nice work! I pulled down the two files and gave them a quick glance, they look really nice. As a SolidWorks user, my only recommendation into your model design, is to build symmetry. For instance, on your fin can, at Boss-Extrude1, use the pull down menu and select Mid Plane. My mentor taught me to always build complete symmetry into a part whenever possible. It can't hurt, and in many circumstances, can help when it comes time to mate assemblies.

 

[TimothyG]

Thanks for the advice. I’m very much still learning how to properly utilize solid works. I spent years using it as a machinist to set up a quick operation but never went beyond extremely basic operations. Best of all I’m in the class at school which means unlimited access to the program right now.

 

[TimothyG]

Wiring, switches, and mounting board arrived. 3D print started with an initial estimate of 38 hours. Excited to see how this turns out. Had my design professor and electronics professor look everything over before starting just in case I’m doing something really dumb. The machinist running the printer liked the simplicity of the mounting tower which gives me hope that I didn’t overthink it. I’ll post pics of it in the morning and at the end of tomorrow and then after it comes out of support dissolve.
Decided to go with silicone coated wire from adafruit after seeing how much abuse the schools robot battle club put it through. And the quarter size board is strong, easy to solder, and has uniform mounting holes making mounting easier. Was initially planning on using a dip switch but talked myself out of that due to making all circuits essentially run through a single component. Separate switches compatible with the breadboard allow separation of the circuits enough to satisfy my paranoia.

 

[OverTheTop]

I thought that printer looked familiar! We have a 1200es that we got for work six years ago. The extruder head died on it in a big way the other day. We have really given it a flogging, so they are looking at throwing it out and buying another printer, rather than repairing. It is already written-off according to the tax man.

 

[TimothyG]

This one is supposedly the oldest printer on campus. Due largely in part to students not being allowed to touch it. I’m friends with the machinist that runs the shop and he’s helping me out with my print at cost which is awesome.

 

[TimothyG]

Couple of pictures of the progress so far. Twenty hours left.

 

[TimothyG]

Received permission to use the equipment at school to do some testing and picked up my sample pieces. Going to braze these back together at home this week and then tear them apart at school. I’ll post the raw data here for anyone who’s interested. I’m firmly settled on durafix simply because it’s been done before and has a bit of already published testing from other rocketry enthusiasts. This testing is to practice graphing data which I’m miserable at and to have something to show my L3 if he asks for first hand knowledge of the brazing rod and it’s performance.

 

[Nytrunner]

Will this be a Balls project due to the metal.content

Received permission to use the equipment at school to do some testing and picked up my sample pieces. Going to braze these back together at home this week and then tear them apart at school. I’ll post the raw data here for anyone who’s interested. I’m firmly settled on durafix simply because it’s been done before and has a bit of already published testing from other rocketry enthusiasts. This testing is to practice graphing data which I’m miserable at and to have something to show my L3 if he asks for first hand knowledge of the brazing rod and it’s performance.
View attachment 374614

Excellent opportunity. I long for the days of being a research student where I had access to equipment like this.

There was just a thread about testing the strength of different bond joints, maybe that person will see this and send you some ideas. Could be a good research project

 

[TimothyG]

Balls is my back up launch date. I have hellfire as my primary cert date.

 

[TimothyG]

Print came out beautifully. Couple of things I’d change. Antenna cord needed more clearance and the connection doesn’t fit very well. I’ll be modifying this print slightly and making due as it’s the only thing really bugging me. In the future it would have been prudent to include mounting holes for some of my other altimeters as now I’m limited on what I can fly on this one. It would have taken no effort to just draw in a couple more holes.

All holes for everything lined up perfect so tonight I’ll start epoxing in mounting pins. Next week I should have time to solder in switching and wires. I want to minimize temporary connections in this rocket.

There will eventually be a Mk2. I think I can fit all this stuff in a sled 4” shorter with another tracker.

 

[Nytrunner]

That is a solid Ebay frame. How heavy Is that?

 

[TimothyG]

460 grams. With electronics and batteries comes out to about a kilo total. I’ll have the weights in my final draft. Should have the paperwork done in a couple more weeks once I machine the aluminum and get pics.
Heaviest parts are definitely the batteries.

 

[TimothyG]

Got most of the wiring done tonight. Also had a chance to weigh most of the parts. For starters the first is the weight with all three altimeters two cameras a tracker and all batteries. Second is weight of just batteries. Then some pictures of the switch board with the three altimeters wired in. Tracker will not be wired to a switch as I don’t see a need to keep it turned off until flight.

 

[OverTheTop]

Neat. When you design the 3D prints think which parts you can leave out (or use clever fill patterns) to save mass. It really is a paradigm shift from the usual subtractive manufacturing. I try to do that but my 3D CAD skills are are still a bit scratchy.

 

[mrwalsh85]

I have a friend who obtained his L3 at Airfest 2018. He had been out of the hobby for several years, came back and got right into the nitty gritty.

Went with a 3" minimum diameter bird on a Loki M3464. I had some skepticism, but I wasn't his TAP, just a buddy... He pulled it off and got his L3. There is a video somewhere on here of that launch. Wicked. I wish I was there, but was about three hours away at a wedding.

In short, do what you want as long as your TAPs are good with it. Keep us updated. Have fun and don't let "go fever" catch up to you

 

[TimothyG]

Just a quick update. I received the brazing rod and have had mixed results with it. Figure I’ll probably burn through this first batch practicing with it until I can produce consistent results before starting on fins.

 

[Nytrunner]

50$ spent in practice beats 500 lost in flight! Good decisions here, love to see how it comes out

 

[plugger]

Hi Timothy,

I wanted to quickly chime in and state that I completely support your decision to attempt your L3 with a minimum diameter rocket. FYI I did the same thing for my L3. Mine wasn't quite as aggressive of a design as what you're pursuing but was still aggressive enough to clock in a max V of Mach 1.93.

Here's a thread with a bit of information.
https://forum.ausrocketry.com/viewtopic.php?f=10&t=4256

I'd also like to mention that one of the benefits of a MD L3 rocket over a big dumb L3 rocket is the fact that you don't need a truck or van to get your rocket to the launch site!

Good luck!

 

[Steve Shannon]

This project is coming along very nicely!
I would also like to point out for the benefit of those who are not yet decided on their L3 rocket that a large range exists between minimum diameter and big dumb rockets. Although those two extremes are mentioned too frequently as if they are the only two choices, it’s not at all necessary to commit strictly to one or the other. A four inch airframe with a three inch motor mount is nothing to sneer at. It’ll still exceed Mach easily using an affordable motor and affordable parts. The certification you receive means the same.

 

[DRAGON64]

True, I chose middle ground for my L3 and went with a 5.5" w/ 3" motor mount. My rocket was not a mach burner, yet it still achieved a nice 6800ft alt in short order (not a BDR).

 

[plugger]

A four inch airframe with a three inch motor mount is nothing to sneer at. It’ll still exceed Mach easily using an affordable motor and affordable parts. The certification you receive means the same.

A four inch airframe using a 98mm to 75mm motor adaptor could be used in this specific instance, the rocket would still have the ability to be a MD bird but could be used to cert L3 on a three inch M class motor and then flown with larger reloads after the cert.

That said my L3 rocket has and will only ever fly once. I lost both my L1 and L2 birds on flights subsequent to the cert flights and I don't have any interest in having that occur with my L3 certification rocket. It's been retired to the shed.

 

[TimothyG]

Plan for this one is to fly it two or three times after my cert flight. I want to fly it on an 80% or greater M motor with a green propellant and I'd like to fly a hard core N motor and final flight possibly the Aerotech O motor but I also kind of doubt I will fly it on that. I'd rather build something higher performance capable of handling a 98mm P motor and work up from the Aerotech O. A big goal of mine is to fly something over Mach 4 at some point and break 100k feet in a single stage but I understand better now then when I started how much more workup this will take. Really big end goal would be to fly something much higher but I've tempered my goals back into the reality of my budget.

Small amount of progress today is I received my some small hardware and new bulkheads from madcow. Got the new bulkheads fitted and they work great. I did a Mk1 on my camera sled but found it to be wanting in so many ways as to not be worth using it for more then mock up and measurements. I'll be flying in March to test the AV bay in another airframe with a J motor to verify that none of my arrangements cause power supply or connectivity problems. Then it's producing the fincan, assembling the remainder of the airframe, and ground testing for test flights on K motor then my first L1000! I'm hoping to also have my replacement K2050 back for a higher G load test flight to verify nothing comes loose or deforms in the printed sled. Then it's save money and prep for flying at hellfire if everything's ready.

 

[Ez2cDave]

A big goal of mine is to fly something over Mach 4 at some point and break 100k feet in a single stage but I understand better now then when I started how much more workup this will take. Really big end goal would be to fly something much higher but I've tempered my goals back into the reality of my budget.

" Speed costs money . . . How fast do you want to go ? "

 

[TimothyG]

I've found a source for a 96" long piece of titanium seamless tubing 98mm if that gives you an idea of how fast and high I want to go. I've machined it before and as long as I can find a lathe with enough bed to run it on I'll make myself a motor casing to run higher pressures in. Like I said I'd love to get a 98mm P motor in the air.