Project 60K: N5800 Contest Rocket

[north boy]

That was a brilliant launch. Loved the ring of dust as the motor ignited at ground 0. Totally awesome guys ....good attempt.

For checking the root for contact couldn't you put a thin coat of paint on the root and push it onto the tube and then remove it instantly to make sure the paint has an even spread all over the tube and there is no patches where it hasn't contacted then remove the paint with the suitable cleaner ???? Just a simple idea to throw in ....

 

[daveyfire]

I see surface mount fins and know they are the weak point, it comes out of my brain ex nihilo.

Elsewhere, you claim to be wedded to analysis. Do the analysis for well-designed surface mounted fins, such as these, using a properly chosen, applied, and cured adhesive. I think the results may surprise you (and everyone else on the "T2TZOMG!!!!!1!!111!!" bandwagon).

Good work Bryce, Tominator, and Jared. That was a failure mode that hadn't crossed my mind. Which is the point of these exercises, no?

 

[New Ocean]

Do the analysis for well-designed surface mounted fins, such as these, using a properly chosen, applied, and cured adhesive. I think the results may surprise you (and everyone else on the "T2TZOMG!!!!!1!!111!!" bandwagon).

The results may surprise me, but the results of real-world flights with surface mount fins has so far not surprised me. (IE shreds as far as the eye can see.)

 

[Tominator 2]

The results may surprise me, but the results of real-world flights with surface mount fins has so far not surprised me. (IE shreds as far as the eye can see.)

Have you heard of Hyperion??? They do the exact same technique on that thing. Mach 5.

https://www.rocketryplanet.com/forums/showthread.php?t=9721&page=3

 

[gdjsky01]

Jeff if I understand what you are saying mill the whole can from one piece of a 14" diameter piece of aluminum? I would classify that as unpractical.

Well, not having any knowledge of these things, I would not have known. The cost of aluminum is something I don't really know. (You mean impractical?)

Thinking of maybe MDARS tomorrow. Never been.
Jeff

 

[bandman444]

Well, not having any knowledge of these things, I would not have known. The cost of aluminum is something I don't really know. (You mean impractical?)

Thinking of maybe MDARS tomorrow. Never been.
Jeff

Totally do able. Just like someone above said. Cost and practicality were my points.

Let me know how MDARS is. Sounds like a cool place.

 

[CarVac]

We (Mudd) wanted to do that but we found an alternative.

 

[bandman444]

A full milled one piece fincan is what is being used with the Harvey Mudd N5800 Team rocketthat will or might fly at Balls this weekend.

Thread here
https://www.rocketryforum.com/showthread.php?41463-Bare-Necessities-N5800-C-Star-Flying-Case

Docs
https://docs.google.com/document/d/1HYh3MNpeld5GMWMje7R8VcdizjjysCkcC63Ja76DTB0/edit?pli=1

PICS
https://www.facebook.com/media/set/?s...3&l=87d00fbb26

Cheers
John ..

Sorry. Not true.

 

[CarVac]

Our fincan is one piece, but the fins are thermal fit into slots in it, instead of the entire fincan and fins being hewn (EDM'd?) from a giant block.

 

[bandman444]

Close to a full milled one piece fincan is what is being used with the Harvey Mudd N5800 Team rocket that will or might fly at Balls this weekend. I see from their docs that the fins are pressed into the slots into fin can and then pinned for extra strength. Very impressive work !!

Thread here
https://www.rocketryforum.com/showthread.php?41463-Bare-Necessities-N5800-C-Star-Flying-Case

Docs
https://docs.google.com/document/d/1HYh3MNpeld5GMWMje7R8VcdizjjysCkcC63Ja76DTB0/edit?pli=1

PICS
https://www.facebook.com/media/set/?s...3&l=87d00fbb26

Cheers
John ..

Oh don't worry. I have spent a lot I time reading their thread, talking to them in person, looking and feeling their rocket. I know what they have done.

My point was that it is not a one piece fin can. Does welding them on count as one piece? Not to me. I think their "attachment" is extremely innovative. I wish I could have seen it work.
They aren't going to Balls tomorrow read the thread you posted twice.

 

[bandman444]

Our fincan is one piece, but the fins are thermal fit into slots in it, instead of the entire fincan and fins being hewn (EDM'd?) from a giant block.

Our fin can was one piece too. We just epoxied them rather than machining it out of a giant block.

Btw I tried looking for a solid hunk that they use for rims, but it looks like the rims are either pressed or molded into the rough shape, then they are CNCd to make whatever design.

What about a molded fin can. Pour in the molten metal and out pops a decent can. Minor trimming required.

 

[rocket1017]

My post has been removed cause it was messed up in too many ways. Sorry guys I should read before posting.
As lady on SNL used to say Never Mind !! :wink:


Cheers
John ..

 

[New Ocean]

Have you heard of Hyperion??? They do the exact same technique on that thing. Mach 5.

https://www.rocketryplanet.com/forums/showthread.php?t=9721&page=3

Yeah I have... looks like 3x the surface area for bonding. How many flights does hyperion have under its belt?

 

[Bojangles]

^^^^ These projects are great, someone's going to figure the n5800
soon. As per fin cans I've been thinking either 3d printed with t2t carbon
or wire edm 7075 aluminum may be some options that haven't been
explored yet. Slightly esoteric and high $$$... I'm real interested to see
If cjl's fins hold up...

 

[edwinshap1]

Wire EDM isn't useful for milling single fins, only for complex shapes and designs like a liquid engine injector or something. Also 7075 isn't better or worse for this application. The annealing is lost on any fin you make out of aluminum.

 

[AHansom]

Wire EDM isn't useful for milling single fins, only for complex shapes and designs like a liquid engine injector or something. Also 7075 isn't better or worse for this application. The annealing is lost on any fin you make out of aluminum.

Did you end up using 7075? What T level did you use?

 

[bandman444]

Did you end up using 7076? What T level did you use?

We used 6061 for our fins. I tried looking it up, but I couldn't find what you mean by "T level".

 

[CCotner]

Wire EDM is still useful for single fins, just not indispensable.

Also, the best option would be selective-laser-sintering a solid Titanium alloy fincan and then heat-treating it...but that's also impractical most of the time. Mudd will be able to do it in a few years, though...

 

[AHansom]

We used 6061 for our fins. I tried looking it up, but I couldn't find what you mean by "T level".

That has to do with the tempering would be like 6061-0 or T4,T6 With O being soft and malleable and T6 stiffer and more brittle

 

[CCotner]

It also has information about other heat treating. For example, our fins were made out of 7075-T651, which is tempered to T6, and then stress-relieved through heat-cool cycles. Therefore the fins did not warp as I machined away material even though it was an extruded plate. The fincan, on the other hand, was 6061-T6, not stress-relieved. The fincan warped out of round when i machined away the outer skin of the can everywhere but where the fins were going to be, flattening out the tube in between the fins. This was a major source of headache in the last week before the launch (when it came time to fit the fincan and fins on the motor case), leading to other delays up to the launch day.

 

[bandman444]

Jared will know. He bought the material and wrote the code. I am just the poor machinist.

 

[Hyperbound]

Wire EDM could be used for a good fincan/mount. I have used Cnc to make these but a wire EDM would do a lot of it. now there are different ways to do this but cutting the length of a fin bracket might be better with a wire EDM then a long end mill like I have used.

Should be making some new ones next week cutting them different so we will see...

 

[Issus]

It is my opinion that the people who have tried (and failed) deserve a lot more respect for their efforts because anybody could sit at your computer and type ideas for the greatest rocket ever, but until you put it on the pad and press the button. It's all talk.

"You learn more from failure that you do from Success"

I personally have learned so much from this project, I am currently making changes on the projects I have coming in the next year to reflect what we have learned last week. I hope when the next time someone is planning a Mach buster they might think about this project and think that maybe its possible with the right surface mount to keep the fins on.

I know I will.

Bryce

I heartily agree - The only way to push these techniques and skills forwards is to do such daring projects. If you look back 20 years I'm sure you'll find aspects of rocketry which were considered rather daring and could never possibly work which are now standard for us. Pioneers of these ideas who were not afraid of failure - more interested in pushing the boundary and seeing what is possible are those who lead the way for the rest of us to achieve great things.

 

[bandman444]

Jared will know. He bought the material and wrote the code. I am just the poor machinist.

Oh. And Project Manager.

 

[bandman444]

That has to do with the tempering would be like 6061-0 or T4,T6 With O being soft and malleable and T6 stiffer and more brittle

T6.

We used 6061-T6

Great question!

 

[edwinshap1]

More specifically T6515. Milled using 3/8" HSS flat end-mill at 5000RPM. End-mill was coated in TiN.

If I do decide to make more fins I'm going to be using a 1/4" Carbide ball end coated in TiAlN. I do need to fix the coolant system before I make any more aluminum fins, though FG is simple enough without coolant, I just need to vacuum constantly.

 

[CarVac]

Just wondering, but what mach number was the rocket projected to be at when the flight first took a tweak at T+2.47 seconds?

 

[bandman444]

Exactly Mach 3 according to our slowest simulation.