"Bells On" - 98mm MD (40K NXRS Project)

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Crash-n-Burn said:
I'm with you, Dave. I thought some of Wilson's wording was off-putting. But why challenge him? Does it really matter? You've said in the past that you don't know why you always end up in these situations. This is why - you don't let these things go. You're a good guy and you contribute a lot to this fourm and the rocketry community. Let it go, brother. You don't need to challenge these things. It isn't worth anyone's effort.

Looking forward to the continued build, Wilson. Looking great so far.
Click to expand...

point... and agreed.
 
Hi everyone - yes, I'm still alive, and so is this project. Just not spending much time on the forums these days (and not because of the nonsense some joker is posting in this thread...well, not entirely anyways) but I should have some updates here in the near future. Haven't done anything on this project since fin tacking due to other rocket (and life) priorities, but there's lots of time still. Next up for Bells On - fillets, layups, av-bay sled, and recovery.

The "younger sister" of this build, Power Line Seeker III, is ahead of this project (but only slightly) and should hopefully fly in a few weeks. The grains are complete (cut, faced, and sanded) and the motor now simply awaits assembly. Fillets are done, but again layups and an av-bay sled await. Hope to get some visuals up on its own build page soon.

Binder Design said:
The fin sweep is cool.
Click to expand...
Hey, an on-topic post! :wink:

That's all for now...
 
blackbrandt said:
-waits with popcorn in hand-
Click to expand...
Wait no longer. ;) Looks like DizWolf may have finally left the building, as well...

Last we left off, fins were tacked on and awaiting fillets.

IMG_4587.jpg
First, we mark the location using pencil lines on my fillet shaping tool (a scrap piece of 54mm liner), and mask accordingly.

IMG_4589.jpg
And anchors aweigh. As with all of my MD rockets these days, Loctite 9462 is applied for fillets. This stuff is amazing - it's thick enough that you can do all 3 (or 4 in this case) sets of fillets while the epoxy is still wet, and they'll hold their shape no problem. Using a mixer nozzle also allows this stuff to be dispensed directly into place, requiring no hand mixing and applying.

IMG_4601.jpg
Not too shabby! I finished the 3rd set of fillets and ran out of glue, so we'll set this aside while we wait on more to arrive.

IMG_4594.jpg
Back to the av-bay. For this rocket, I'm using a Raven3 and a StratoLogger CF.

IMG_4597.jpg
Av-bay sled (3/16" plywood) starting to take shape with altimeters and switches mounted. This rocket marks my first time using Featherweight magnetic switches, something I had been wanting to do for a long time. Hopefully they'll be worth the money! Note their closer location to the outside of the bay, which should make for easier arming.

Next up - fillets v2, av-bay v2, layups, and recovery.
 
BTW - you do know that you can't fly to 40k at Brothers with a research motor....
Must stay under 90% of the waiver.
 
May I ask a question,,
I love the fin shape,, very much..
What makes this shape so sexy is the sweep back,,
the aft edge of the root being fore of the aft edge of the tip...
I thought you shouldn't do this on a bird that can achieve great velocity...
I thought you're increasing the ability for the fin to oscillate and flex at the tip...

I'm sorry,, I'm certain an engineer could explain what I'm trying to say much more effectively...

Teddy
 
I think the purpose of that trailing edge is to ensure vortices shed off the tips instead of impinging on laminar body flow?

I'm putting it out there to be corrected :D
 
AlnessW said:
View attachment 292112
Av-bay sled (3/16" plywood) starting to take shape with altimeters and switches mounted. This rocket marks my first time using Featherweight magnetic switches, something I had been wanting to do for a long time.
Click to expand...

Isn't one of your switches pointed the wrong direction? Looks like the magnet sensor is facing inwards. What I don't care for about these switches is that you almost need another switch on the battery lead. If you leave them hooked up for too long they'll drain the battery. I like to prep my bay sans charges weeks or months ahead of time. Just load the BP and go.
 
dhbarr said:
I think the purpose of that trailing edge is to ensure vortices shed off the tips instead of impinging on laminar body flow?

I'm putting it out there to be corrected :D
Click to expand...

For my builds having a slight sweep helps the stability numbers and allows me to optimize for better altitude (with a smaller span and thus less drag for example).
Not sure if you also get the benefit you mention.

Onebadhawk - I think it's a function of several things; span, stiffness, amount of sweep etc.
For relatively small span, stiff fins (with carbon tip to tip for example) it can work fine.
 
Zebedee said:
For my builds having a slight sweep helps the stability numbers and allows me to optimize for better altitude (with a smaller span and thus less drag for example).
Not sure if you also get the benefit you mention.

Onebadhawk - I think it's a function of several things; span, stiffness, amount of sweep etc.
For relatively small span, stiff fins (with carbon tip to tip for example) it can work fine.
Click to expand...

This all makes great sense..
I was no aware at all swept back would would optimize for altitude..
I wish ya told me that before,, lol...
I thought fins in the shape of,, for a classic example,, The Intimidator,, were optimized for performance overall..
And if they are less draggy then you'd get more altitude as a function of having less drag...

Teddy
 
AlnessW said:
Back to the av-bay. For this rocket, I'm using a Raven3 and a StratoLogger CF.

View attachment 292112
Av-bay sled (3/16" plywood) starting to take shape with altimeters and switches mounted. This rocket marks my first time using Featherweight magnetic switches, something I had been wanting to do for a long time. Hopefully they'll be worth the money! Note their closer location to the outside of the bay, which should make for easier arming.

Next up - fillets v2, av-bay v2, layups, and recovery.
Click to expand...

Really nice build so far. Can you do me a set of fins for my 3" project?

Couple of questions. Why the magnetic switches? What are your thoughts on these? Why not internal screw switches, or the like?

Second question. If the beastie is all fiberglass..... why is the AV sled plywood?
 
Good comments here folks, thanks!

FredA said:
BTW - you do know that you can't fly to 40k at Brothers with a research motor....
Must stay under 90% of the waiver.
Click to expand...
Right - sims are topping out around 37K or so which is well within the 90% limit.
I have a hotter motor in the works for BALLS...

Binder Design said:
Isn't one of your switches pointed the wrong direction? Looks like the magnet sensor is facing inwards. What I don't care for about these switches is that you almost need another switch on the battery lead. If you leave them hooked up for too long they'll drain the battery. I like to prep my bay sans charges weeks or months ahead of time. Just load the BP and go.
Click to expand...
You may be right on orientation - I'll have to double-check.

And yes, I'm adding a connector to the battery leads following your (and others) advice to avoid draining the battery. Not another switch, just a JST connector which I'll hook up during av-bay prep. I like to prep ahead of time too, but final av-bay assembly for this rocket will take place on-site since the same bay will house trackers as well. If possible, I don't like leaving those powered on for hours on end, either.

Zebedee said:
For my builds having a slight sweep helps the stability numbers and allows me to optimize for better altitude (with a smaller span and thus less drag for example).
Not sure if you also get the benefit you mention.

Onebadhawk - I think it's a function of several things; span, stiffness, amount of sweep etc.
For relatively small span, stiff fins (with carbon tip to tip for example) it can work fine.
Click to expand...
Zebedee is exactly right - helps stability, optimizes for altitude, and as you mention, just plain sexier. :wink:

Salvage-1 said:
Really nice build so far. Can you do me a set of fins for my 3" project?

Couple of questions. Why the magnetic switches? What are your thoughts on these? Why not internal screw switches, or the like?

Second question. If the beastie is all fiberglass..... why is the AV sled plywood?
Click to expand...
Thank Rob! Yep, more than happy to cut/bevel G10 fins - just let me know.

Magnetic switches - for starters, I've just always wanted to try these out and see how I like them. And yes, I do use internal screw switches on all of my other av-bays and I quite like those. This particular setup requires no additional holes for switches, just wave a "magic wand" (neodymium magnet) over location, and altimeter powers on. Again, somewhat of a proof-of-concept (for me anyways), but we'll see how it goes.

I use plywood sleds for multiple reasons:
Lighter
Cheaper
Easier to cut
Easier to mount to
More forgiving - holes don't need to be drilled in as precise locations.
 
AlnessW said:
Good comments here folks, thanks!


Right - sims are topping out around 37K or so which is well within the 90% limit.
I have a hotter motor in the works for BALLS...
Click to expand...

I may be doing the math wrong, but wouldn't 90% x 40,000' = 36,000'?
 
RocketFeller said:
I may be doing the math wrong, but wouldn't 90% x 40,000' = 36,000'?
Click to expand...
Your math is right but the max ceiling is wrong. It is 42,460' AGL so maximum for EX flights would be 38,214'. Again, unless I'm missing something...
 
NXRS is now a mere 9 days away (that's horrifying - where in the world did all that time go), so it's crunch time.
Since my last update, the motor for this project is now 100% mixed (but not complete - motor still awaits gluing and assembly) which is huge.

IMG_1374.jpg
Man your battle stations. My 20 qt. mixer powering through 13,300g of 82% solids propellant and not even breaking a sweat.

IMG_1375.jpg
A day or so later. Everything poured great - and those 75mm grains are for another motor...

IMG_1391.jpg
Completed, cored, sanded, and faced grains. These came out really well, definitely some of the best I've ever made. Liner/case/motor parts are all ready to go now as well, and assembly should take place by this weekend.

Last we had left off with the airframe, fillets were 75% complete following an epoxy "shortage." (You go through a lot of the stuff when doing big fillets x 8.) Those have since been completed, so moving on to layups now.

IMG_1389.jpg
First, trace fin template on to paper and mark 12K carbon fiber cloth accordingly x 4. Cutting thick carbon like this is always a real challenge - frays easily and little bits end up all over the place. Then, mix up a massive batch of Aeropoxy PR2032/PH3630 and press carbon into place. The lighting in this photo makes it look lumpy for some reason, but it actually came out quite smooth, especially after everything spreads out/settles.

My av-bay is now mostly wired as well and awaits solder, connectors, and terminal blocks/charge holders. Will have visuals of that soon...

Next on the agenda - trimming/sanding/clean-up of fin can, motor assembly, av-bay work, and recovery. Getting closer by the day, but no time to stand down.
 
FredA said:
Don't suppose you can post a burnsim printout of that 4G98?
Click to expand...
Fred - I appreciate your concern, but not sure why your activity on this forum consists almost entirely of insinuating (publicly) that my efforts are misguided, inadequate, and apparently sorely lacking in criticism. If you really think that my third N motor (did you catch the results of the first 2?) poses a safety concern, at least have the decency and politeness to contact me a) privately and b) directly. Thanks and we'll see you in the sage.
 
Last edited:
Interesting response....I see nothing critical in my post....you got some sort of persecution complex?
Just asking if you've got a sim of this motor.
Paranoid or something????
Or is the answer NO and you are unwilling to just admit it?
 
Last edited:
FredA said:
Interesting response....I see nothing critical in my post....you got some sort of persecution complex?
Just asking if you've got a sim of this motor.
Paranoid or something????
Or is the answer NO and you are unwilling to just admit it?
Click to expand...

No Burnsim. Now that would be bad. Let's hope that is not the case.
 
You just kicked a sleeping bear:mad:.

Wilson, nice job on the rocket, and I look forward to watching the result! Hope all goes well and you find 37k'!

Regarding Burnsim and sims in general: I know a guy that makes pretty decent RX motors without having owned a copy of Burnsim. After 120 EX motors burned (120/120 successful), I did invest in Burnsim, 'cause it's a great program and Greg is a great guy....not because I needed a simulation program to do the thinking for me. By that time, I had successfully designed, built, and flown 7 98mm motors (4-7grain) in AMW, Trucore, Aerotech, and CTI hardware....not looking for a sticker or trophy, but I didn't need any commercially available simulator to do what Wilson is doing here! Similarly, I invested in Rocksim only because it was required for the Class 3 stuff. Yes, I'm a walking contradictions....an old fashioned millennial! A person that believes that much of the modern technology has thoroughly dumbed down human existence...no longer do we need skills or even a basic understanding of things, we can rely on computer programs to do all the work for us! As technology and automation gets smarter, people get dumber. Crap in, crap out: data entry without people having any understanding of what's really going on. It's really, really sad, actually!

Disclaimer: I did "pop" a motor in May of this year...tried something different and pushed things pretty hard....first CATO in a public setting...ironically after being an owner of Burnsim....ooops!

Sorry, hit a nerve. We have enough negativity and animosity in this place; don't need more, you'll just drive yet more people out. Humble the superiority complex, offer genuine help when necessary, and offer a little encouragement and support once in a while! Jeesh!

-Eric-
 
Last edited:
When are you planning to launch? I would definitely like to see it go up if able!

We are planning to be there Saturday and Sunday morning. I am going to try to be there Friday by myself, but I don't know what time.
 
"walking contradictions" that can do this all in their heads are rare - Frank K was one of them... EricC might be one....Wilson is not.
"Designing" motors based solely on the Kn range that was "published" with a formula is not a valid path for someone dedicated to EX especially when building large N's.
Hopefully that's not the case here....that's why I asked to see a sim....
 
ECayemberg said:
You just kicked a sleeping bear:mad:.

Wilson, nice job on the rocket, and I look forward to watching the result! Hope all goes well and you find 37k'!

Regarding Burnsim and sims in general: I know a guy that makes pretty decent RX motors without having owned a copy of Burnsim. After 120 EX motors burned (120/120 successful), I did invest in Burnsim, 'cause it's a great program and Greg is a great guy....not because I needed a simulation program to do the thinking for me. By that time, I had successfully designed, built, and flown 7 98mm motors (4-7grain) in AMW, Trucore, Aerotech, and CTI hardware....not looking for a sticker or trophy, but I didn't need any commercially available simulator to do what Wilson is doing here! Similarly, I invested in Rocksim only because it was required for the Class 3 stuff. Yes, I'm a walking contradictions....an old fashioned millennial! A person that believes that much of the modern technology has thoroughly dumbed down human existence...no longer do we need skills or even a basic understanding of things, we can rely on computer programs to do all the work for us! As technology and automation gets smarter, people get dumber. Crap in, crap out: data entry without people having any understanding of what's really going on. It's really, really sad, actually!

Disclaimer: I did "pop" a motor in May of this year...tried something different and pushed things pretty hard....first CATO in a public setting...ironically after being an owner of Burnsim....ooops!

Sorry, hit a nerve. We have enough negativity and animosity in this place; don't need more, you'll just drive yet more people out. Humble the superiority complex, offer genuine help when necessary, and offer a little encouragement and support once in a while! Jeesh!

-Eric-
Click to expand...

Eric,

You know me. I'm not inherently mean or judgmental. My comment was only based on safety considerations. I would be interested in seeing your motor design process if you could share it privately (if you prefer, as you have been so successful). What I worry about, and what was drilled into me by my mentor (our friend), Dr. David Reese, was to understand the parameters and full effects of a motor design going back to the fundamental chemistry and math. Can I do the math by hand, sure, but I utilize PROPEP and Burnsim as tools to assist in the analysis, not as a crutch or excuse for not thinking. Maybe you and Wilson do this analysis by hand instead. The fear in my mind are those that never received quality mentoring and instead are just reading recipes, scaling and modifying without any fundamental foundation in the chemistry and math. I did not mean to imply Wilson had a lack of understanding and I shouldn't have been quick to say not using Burnsim is bad. You are right, there are other ways to accomplish the end goal as long as the design work is not ignored and basic assumptions made without full understanding of their effects. I will repeat for emphasis, it is all about safety. The privileges of participating in High Power Research launches comes with it, extreme responsibility.

-Tim
 
Last edited:
FredA said:
"walking contradictions" that can do this all in their heads are rare - Frank K was one of them... EricC might be one....Wilson is not.
"Designing" motors based solely on the Kn range that was "published" with a formula is not a valid path for someone dedicated to EX especially when building large N's.
Hopefully that's not the case here....that's why I asked to see a sim....
Click to expand...

Fair enough, Fred. Not at all against asking for proof of concept, etc; I'm just a curmudgeon against the requirement for *some* simulators (I'm still bitter I had to purchase RSim for the Class 3 documentation...vastly prefer RASAero!):cyclops:. Burnsim is a truly wonderful program however!!!

I'm no Frank. I love Frank's motors, I enjoyed chatting with him, I miss him. Got a new phone Tuesday and saw his name in my transferred contacts....made me sad all over again, but smile at past interactions!

Back to Wilson, I'm all for safety! I like to see various projects and ambitions...so long as they're done in a safe and sane manner I think ambitious projects that push one's limits are wonderful. I'm pulling for you, Wilson! After all, I once certified a young man/father team at Bong Rec. Area...as a relatively new Prefect at the time, this kid comes up to me wanting to fly a tiny rocket on a nearly full I motor (at Bong...read that: limited recovery area). I thought he was nuts, I told him it was a fairly ambitious attempt considering the location/conditions, but the team proceeded regardless. The rocket disappeared from the pad, I felt bad for the team thinking they had lost their L1 attempt. Hours later, up walks Manny, covered in ticks, mosquito bites, mud and blood, with his rocket in hand after a wild recovery adventure. I thought he was nuts before the flight, I knew I was right after the flight!:wink:

-Eric-
 
dixontj93060 said:
Eric,

You know me. I'm not inherently mean or judgmental. My comment was only based on safety considerations. I would be interested in seeing your motor design process if you could share it privately (if you prefer, as you have been so successful). What I worry about, and what was drilled into me by my mentor (our friend), Dr. David Reese, was to understand the parameters and full effects of a motor design going back to the fundamental chemistry and math. Can I do the math by hand, sure, but I utilize PROPEP and Burnsim as tools to assist in the analysis, not as a crutch or excuse for not thinking. Maybe you and Wilson do this analysis by hand instead. The fear in my mind are those that never received quality mentoring and instead are just reading recipes, scaling and modifying without any fundamental foundation in the chemistry and math. I did not mean to imply Wilson had a lack of understanding and I shouldn't have been quick to say not using Burnsim is bad. You are right, there are other ways to accomplish the end goal as long as the design work is not ignored and basic assumptions made without full understanding of their effects. I will repeat for emphasis, it is all about safety. The privileges of participating in High Power Research launches comes with it, extreme responsibility.

-Tim
Click to expand...

Agree wholeheartedly; all in the eyes of safety! Just felt as if Mr. Alness has been the victim of being "piled on" in this thread...always hate to see that happen. When someone takes the time to post their efforts, whether great or small, successful or not, it's always a bummer when their is lash out against those efforts....almost like being punished for selflessly sharing info.

I'll go back into hiding now...:)
 
FredA said:
Interesting response....I see nothing critical in my post....you got some sort of persecution complex?
Just asking if you've got a sim of this motor.
Paranoid or something????
Or is the answer NO and you are unwilling to just admit it?
Click to expand...

Your contributions to this thread so far have been a) asking for the "Summer's Eve" meme to return, b) saying my project will violate TRA rules on the waiver, and c) hoping to expose my presumed lack of knowledge regarding motor design. You know what you're doing just as well as I do, but certainly you of all people also know that I cannot post EX motor details in the open forum as it is against TRF rules. And I am a rule follower, just like yourself. I have zero interest in blowing up motors, and I have yet to blow up one. Naturally, of course I have BurnSim and of COURSE I have a file. I also know it will work because I've flown that same motor twice before with perfect results. I could email you the file, but then I'd just be exonerating myself when there was clearly no lack of due diligence to begin with. In my last build thread, your contribution was that I didn't know the rules on decent rates and would likely break them. That rocket went 34K, over Mach 2, and recovered safely. Give it a rest, please.

ECayemberg said:
You just kicked a sleeping bear:mad:.

Wilson, nice job on the rocket, and I look forward to watching the result! Hope all goes well and you find 37k'!

Regarding Burnsim and sims in general: I know a guy that makes pretty decent RX motors without having owned a copy of Burnsim. After 120 EX motors burned (120/120 successful), I did invest in Burnsim, 'cause it's a great program and Greg is a great guy....not because I needed a simulation program to do the thinking for me. By that time, I had successfully designed, built, and flown 7 98mm motors (4-7grain) in AMW, Trucore, Aerotech, and CTI hardware....not looking for a sticker or trophy, but I didn't need any commercially available simulator to do what Wilson is doing here! Similarly, I invested in Rocksim only because it was required for the Class 3 stuff. Yes, I'm a walking contradictions....an old fashioned millennial! A person that believes that much of the modern technology has thoroughly dumbed down human existence...no longer do we need skills or even a basic understanding of things, we can rely on computer programs to do all the work for us! As technology and automation gets smarter, people get dumber. Crap in, crap out: data entry without people having any understanding of what's really going on. It's really, really sad, actually!

Disclaimer: I did "pop" a motor in May of this year...tried something different and pushed things pretty hard....first CATO in a public setting...ironically after being an owner of Burnsim....ooops!

Sorry, hit a nerve. We have enough negativity and animosity in this place; don't need more, you'll just drive yet more people out. Humble the superiority complex, offer genuine help when necessary, and offer a little encouragement and support once in a while! Jeesh!

-Eric-
Click to expand...
Echoing your comments on BurnSim - I too, use it as a tool, but not as a crutch or a "word of god." No substitute for common sense! And thank you for the kind words. I too, can't wait to fly this and hit 37K!

dixontj93060 said:
Eric,

You know me. I'm not inherently mean or judgmental. My comment was only based on safety considerations. I would be interested in seeing your motor design process if you could share it privately (if you prefer, as you have been so successful). What I worry about, and what was drilled into me by my mentor (our friend), Dr. David Reese, was to understand the parameters and full effects of a motor design going back to the fundamental chemistry and math. Can I do the math by hand, sure, but I utilize PROPEP and Burnsim as tools to assist in the analysis, not as a crutch or excuse for not thinking. Maybe you and Wilson do this analysis by hand instead. The fear in my mind are those that never received quality mentoring and instead are just reading recipes, scaling and modifying without any fundamental foundation in the chemistry and math. I did not mean to imply Wilson had a lack of understanding and I shouldn't have been quick to say not using Burnsim is bad. You are right, there are other ways to accomplish the end goal as long as the design work is not ignored and basic assumptions made without full understanding of their effects. I will repeat for emphasis, it is all about safety. The privileges of participating in High Power Research launches comes with it, extreme responsibility.

-Tim
Click to expand...
Yes...see above answer.
 

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