Madcow Tomach Build Thread - "Not an Engineer"

tfish said:

I do like Steve posted above. I did a 3" min dia one time and I needed all the space I could salvage. I ended up making a 2 piece nylon ring. Freed up enough more space for about 5 more feet of shock cord. These also make good rail button attachment point too.

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Slimline is definitely out - glad I hadn't ordered it yet. I may add something to the forward end in addition to the friction fit.

Nice Wilson, just caught up on your thread

The Cylon Rocketeer said:

Nice Wilson, just caught up on your thread

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Thanks Ed for stopping by!

Ditto, just caught up! I'm looking forward to seeing this fly! It will probably blow the stripes off my shred race entry!

Where did you get the hardware for your nose cone assembly? Think I might do something similar on a 54mm kit I'm doing.

-e

I've been following this build as well. My Tomach is arriving on Monday, so your build will serve as a kind of guide.

emckee said:

Ditto, just caught up! I'm looking forward to seeing this fly! It will probably blow the stripes off my shred race entry!

Where did you get the hardware for your nose cone assembly? Think I might do something similar on a 54mm kit I'm doing.

-e

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Thank you Erik! Curious to see what you end up flying for your shred racer... Getting 2 flights up within an hour of each other could prove to be a challenge for me (I'm in the 75mm race as well), but I pondered it a bit today and I think I can make it work. As always, can't wait for NXRS this year!

I get my nosecone hardware from a local "mom and pop" feed and hardware store. ACE Hardware would probably have them too. Of course, so does McMaster, unless you want bags of 100 each while paying for ground shipping...

rc dude said:

I've been following this build as well. My Tomach is arriving on Monday, so your build will serve as a kind of guide.

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Sweet! Let me know if you have any questions and I'd be happy to assist. Might this be for an L1 and/or L2 cert?

Hi Wilson,

Your progress is looking great. I see you ended up with an internal retainer system. I decided on the same route but as I already had the MD Aero Pack I just drilled and tapped 3 holes in the Aero Pack to be able to remove or even move it to accommodate different sized hardware. I am still in the air on rail vs. tower, or even if these fly-away rail guides will even be an option.

Have you decided on your maiden motor choice?

For my maiden test-out I am leaning towards an AT I599N, which will keep it low and slow but allow me to test the deployment and tracking. If everything works as it should then I am going to use this for my L2 but want to have some fun with the attempt. So I am going with Loki 54/2800 hardware and was all set on a K350 moon burner (6.4 seconds of thrust, love those long burning motors) EAGL 16-17K @ Mach 1.1. Then Scott had to throw a wrench in my plans by releasing a new L1040 Loki red, which puts it closer to 20K @ Mach 1.7.

Either choice will be firsts for me, breaking 10K and Mach.

AlnessW said:

Thank you Erik! Curious to see what you end up flying for your shred racer... Getting 2 flights up within an hour of each other could prove to be a challenge for me (I'm in the 75mm race as well), but I pondered it a bit today and I think I can make it work. As always, can't wait for NXRS this year!

I get my nosecone hardware from a local "mom and pop" feed and hardware store. ACE Hardware would probably have them too. Of course, so does McMaster, unless you want bags of 100 each while paying for ground shipping...


Sweet! Let me know if you have any questions and I'd be happy to assist. Might this be for an L1 and/or L2 cert?

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It is for both actually.

Unfortunately, all the Ace Hardware stores in my area are closing down. A real shame. Some were fantastic suppliers for misc items that home depot never carries.

mpitfield said:

Hi Wilson,

Your progress is looking great. I see you ended up with an internal retainer system. I decided on the same route but as I already had the MD Aero Pack I just drilled and tapped 3 holes in the Aero Pack to be able to remove or even move it to accommodate different sized hardware. I am still in the air on rail vs. tower, or even if these fly-away rail guides will even be an option.

Have you decided on your maiden motor choice?

For my maiden test-out I am leaning towards an AT I599N, which will keep it low and slow but allow me to test the deployment and tracking. If everything works as it should then I am going to use this for my L2 but want to have some fun with the attempt. So I am going with Loki 54/2800 hardware and was all set on a K350 moon burner (6.4 seconds of thrust, love those long burning motors) EAGL 16-17K @ Mach 1.1. Then Scott had to throw a wrench in my plans by releasing a new L1040 Loki red, which puts it closer to 20K @ Mach 1.7.

Either choice will be firsts for me, breaking 10K and Mach.

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Thanks for the nice note! Yes, at best I will be using some sort of internal retainer, but we determined that the Aeropack MD won't work with a snap-ring case. I'll probably end up using something of my own design.

My overall goal for this project is to have the first flight be on one of my own motors. The plan for now is to fly an L-something my Fisher 54/2800 case. Your flight plan sounds good, and I am looking at about 20K as well.

rc dude said:

It is for both actually.

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Awesome!

emckee said:

Unfortunately, all the Ace Hardware stores in my area are closing down. A real shame. Some were fantastic suppliers for misc items that home depot never carries.

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Bummer - I've found that to be true of my local ACE (still open) as well. Not sure where else you'd look other than smaller hardware stores... Did you say you're doing a 54mm project as well?

I guess my excuse for not updating this thread very often is that Aeropoxy ES6209 takes so damn long to fully cure...
Anyways, I finally worked on this thing these past couple days.


The kit came with 30' of tubular nylon, so the logical thing is to use 15' in each section. That yields 3x the length of the rocket in each section, for a total of 6x when everything is fully deployed. That feels like plenty. Here we have the drogue harness, but no need for a chute since I'll obviously be going drogueless.

With the 54/2800 case loaded, I only have about 3-4 inches of room in the booster section. Cramming 15' of harness in there was a tight fit, but I really think it'll work. If need be I can shorten the harness to 10' or 12', or better yet switch to a Kevlar cord...


And the main harness with a 36" PML chute in place. Once I calculate the decent rate I may end up using a 45" octagon, but I have a feeling that the 36" will be more than enough.


Did the first set of fillets today using ES6209. Note I'm not too worried about prettiness at this point, since these will all be underneath fiberglass cloth...

AlnessW said:

Here we have the drogue harness, but no need for a chute since I'll obviously be going drogueless.

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Why drogueless? Is there something you calculated that tells you the two halves will fall at the same rate and not hit each other? That the upper half won't go ballistic and drag the fin can with it?

Without a drogue, you have no control over how the rocket falls. It will probably be OK, but you're just betting on the odds if you don't use a drogue and exert positive control over that part of the recovery. Sooner or later the odd usually even out.

Handeman said:

Why drogueless? Is there something you calculated that tells you the two halves will fall at the same rate and not hit each other? That the upper half won't go ballistic and drag the fin can with it?

Without a drogue, you have no control over how the rocket falls. It will probably be OK, but you're just betting on the odds if you don't use a drogue and exert positive control over that part of the recovery. Sooner or later the odd usually even out.

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Yes of course - as long as you're destreamlined...

Your build is looking good. What did you use to form the fillets?

rc dude said:

Your build is looking good. What did you use to form the fillets?

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Thanks! I use tongue depressors (wide popsicle sticks) for my fillets.

Handeman said:

Why drogueless? Is there something you calculated that tells you the two halves will fall at the same rate and not hit each other? That the upper half won't go ballistic and drag the fin can with it?

Without a drogue, you have no control over how the rocket falls. It will probably be OK, but you're just betting on the odds if you don't use a drogue and exert positive control over that part of the recovery. Sooner or later the odd usually even out.

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AlnessW said:

Yes of course - as long as you're destreamlined...

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Sorry about that. It's just my touch point. Going drogueless works almost all the time, but most people don't realize how close they come to disaster on a lot of flights. If the main opens and doesn't tangle, they feel it's successful. The extreme shock these types of recovery profiles put on the recovery system survives on lighter rocket very well, not so much on large L2 or L3 rockets. They are correct, it is successful, but when the fin can glances off the opening main because the payload was coming down ballistic and pulling the fincan down with it, that is a near miss in my book. Most people consider it a perfect flight.

Like I said, that's just my touch point.

Handeman said:

Sorry about that. It's just my touch point. Going drogueless works almost all the time, but most people don't realize how close they come to disaster on a lot of flights. If the main opens and doesn't tangle, they feel it's successful. The extreme shock these types of recovery profiles put on the recovery system survives on lighter rocket very well, not so much on large L2 or L3 rockets. They are correct, it is successful, but when the fin can glances off the opening main because the payload was coming down ballistic and pulling the fincan down with it, that is a near miss in my book. Most people consider it a perfect flight.

Like I said, that's just my touch point.

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Ah, I see. A "perfect recovery" in my book is when you get your bird open at apogee, then deploy a big chute closer to ground level with a soft landing...

AlnessW said:

Ah, I see. A "perfect recovery" in my book is when you get your bird open at apogee, then deploy a big chute closer to ground level with a soft landing...

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I understand. By that definition, the Titanic would have had a "perfect cruise" if it had made it to New York because they missed the iceberg by less then a foot.

AlnessW said:

Ah, I see. A "perfect recovery" in my book is when you get your bird open at apogee, then deploy a big chute closer to ground level with a soft landing...

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Please clear out some of your PM inbox so you can get a message.
Thanks,

Loki Research said:

Please clear out some of your PM inbox so you can get a message.
Thanks,

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Just cleared out some old PMs - should be good to go now.

Handeman said:

I understand. By that definition, the Titanic would have had a "perfect cruise" if it had made it to New York because they missed the iceberg by less then a foot.

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Um...I guess you could say that...

Sorry to drop off the planet on you all. These past few months have been far too busy with school, moving, traveling, and other priorities. I had hoped to have this rocket ready for NXRS next weekend, but it's pretty unlikely at this point... Next opportunity would be end of July.

Admittedly, I hadn't touched this rocket since April or thereabouts...until tonight!

I can't upload an image to TRF right now... ?!?! So I am embedding directly from my site:



Just did the second set of fillets, which came out nicer than I imagined!

AlnessW said:

Sorry to drop off the planet on you all. These past few months have been far too busy with school, moving, traveling, and other priorities. I had hoped to have this rocket ready for NXRS next weekend, but it's pretty unlikely at this point... Next opportunity would be end of July.

Admittedly, I hadn't touched this rocket since April or thereabouts...until tonight!

I can't upload an image to TRF right now... ?!?! So I am embedding directly from my site:

Just did the second set of fillets, which came out nicer than I imagined!

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My rocketry has had a backseat also. Good luck on getting airborne. I have most of the stuff for my 54 MD scratch build and have done a little work. Just need to put it together and go.

4kids49 said:

My rocketry has had a backseat also. Good luck on getting airborne. I have most of the stuff for my 54 MD scratch build and have done a little work. Just need to put it together and go.

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Thanks! Yep, putting my projects on the fast-track now. Good luck on your flight!

Finally making some headway on this thing!

Updated build page can be found here: https://wilsonalness.com/rocketry/projects/tomach.html


Finished up the last set of fillets and also glued down a set of weld nuts, where the rail buttons will attach to.

Before I say anything else, there is a part of me that really wants to just try flying this thing as it is, no fiberglass layups or anything. But since I'd rather get more than 1 flight out of this rocket, on to the tip-to-tip...


First, we cut paper template of the fins.


Then cut a few sections out of fiberglass cloth. Not sure why this came out blurry...


Tada! Soak a section in Aeropoxy PR2032/PH3630, then apply it to the fins. I did 2 sets of fins today and will likely do the 3rd tomorrow. Then once that all has cured, add a second layer of fiberglass just for insurance. Big thank you to Jeremy (aka junkyard) for selling me all the composites/adhesives I needed to build this thing, as well as loaning me some nifty little tools to help spread all the epoxy out.

By the way, I'm thinking of maybe naming this rocket "Not an Engineer," referring to my planned career path. :wink:

Oh, come on! Engineering is AWESOME! Just imagine, if you do it right, you could get paid for this type of stuff!

Lookin great wilson

emckee said:

Oh, come on! Engineering is AWESOME! Just imagine, if you do it right, you could get paid for this type of stuff!

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junkyard said:

Lookin great wilson

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Thanks gentlemen!


2nd layer of tip-to-tip.


Now finally time to clean this thing up a bit!


Lastly, some bevels and I think I can finally put this fin can project to bed...

I had planned to fly this thing last weekend, but got cold feet after my previous launch that day...

I think I've officially set a personal record for the longest it's ever taken me to build a rocket...

At long last, I can finally say this project is DONE, right down the motor! I just wrapped up the last little finicky parts like drilling vent holes in the airframe/av-bay, etc. Will add paint later.


Here she is, all ready to fly. Motor is a 30" x 54mm baby L I cast a few weeks ago, housed in the Fisher case. Should get it moving. :wink:

The 30" case plus av-bay coupler yields about 3" of 54mm airframe to house recovery gear. Gulp... Somehow I was able to cram all 15' of my harness in there, along with the 3/8" forged eyebolt on the motor's front closure, but just barely! No room for forward motor retainers, or anything else really.

Only problem now is where to fly it. Our club launch this month got cancelled due to fire danger, next opportunity will be BALLS at the end of September. I'm bummed that this thing will have to sit around here for another month, but patience is a virtue...

Decided on the name too!

Looks great! No getting too bummed about cancelled launches, as my L3 attempts keep getting scrubbed. Oh well, I suppose it will make BALLS that much more awesome!