I'll Have Another - 4in to 3in Two Stage

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prophecy

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Don't see much value in any kind of build thread other than a Cayemberg-style, stream of consciousness diary/documentary, so here goes, follow along if you wish.

Background:

I've had a run of bad luck recently with getting my projects in the air - after a very encouraging flight of the 4" composite-cased N6000 at Airfest in August, we returned to Texas and immediately upscaled it to a 5" composite case with the same propellant for Balls three weeks later through a seemingly endless series of all-nighters. This was to end in heartbreak on the playa, as we were vertical on the rail and about to arm under clear blue skies, all on the range were told to stand down while the FAA was consulted about the approaching cloud cover; the range never re-opened, so 28 hours home we went. My buddy's Balls project was grounded as well, as our plan had been to fly mine on Saturday and his on Sunday, so our recourse seemed to be to apply for our own waiver in New Mexico in coordination with the TRA White Sands folks. Our target date to have the waiver in hand was Nov. 22, but it became clear that the process would take far longer than this date (still a work in progress). While we waited, I took some of the scrap parts left over from the summer's projects and put together a little 3" min dia thing to fly at a local launch just to bide my time, and said local launch has been cancelled three times and counting. When it rains, it pours.

The waiver application is through June, so once we do get the waiver, it's only right to use it not only to fly the old projects, but to build new projects that we otherwise wouldn't be able to fly anyway save for the annual Black Rock trip (which is usually reserved for one, larger project). While I tend to gravitate towards aluminum fincans for my Black Rock projects, my heart really lies in my ever-ongoing series of no-layup, stock-part fiberglass builds, seeing how far I can stretch cost-effective and readily-available parts that are normally used for basic sport flying (and are well overqualified for that application). For some reason, I find so much more satisfaction in pushing common parts past their intended limits than I do building something highly customized and pimped out. Additionally, while my Black Rock projects tend to be one-offs (which restricts the learning curve pretty heavily), this series of no-layup fiberglass builds has been ongoing for several years running now, so I've enjoyed learning and improving with each round of revisions (and have yet to have an issue with the structural integrity of any of them in flight). A brief run-down of the no-layup rockets/flights so far:

Unnamed 3" project - 6000ns motor - June 2013, Potter, NY
Keep the Change - 4" project - 17500ns motor - July 2013, Argonia, KS
Alpine Style - 3" project - 7600ns motor - July 2014, Argonia, KS
I'll Have Another - named seemed appropriate, and named after the famous racehorse that came within an inch of the Triple Crown in May 2012 (still one of the most exciting Derby wins I've ever seen) - 4" to 3" two-stage - 18000ns to 6000ns motors - ? 2015, Las Cruces, NM

So here's what we've got. I was lucky enough last week to score a 45" length of 4" FWFG tube from my friend Dan, and the original plan was to build rev2 of Keep the Change (single-stage 4"), try and find it after flight this go round, and shoot for 45k. But then 3" FWFG parts came up for sale (thanks, littlemisterbig), and we've got plenty of room left in our potential waiver, so why not try a two stage?

So I have a 45" x 4" airframe, a 36" x 3" airframe, and a 3" nosecone on the way. I went ahead and ordered a 12" x 24" sheet of G10 from McMaster (the usual .125"), as well. Opted to give Rocketpoxy a try this time (all the previous builds have been using Proline 4500, but since Rocketpoxy is 1:1, the pint kit is actually two pints of epoxy for the same price as one pint and change of 4500).

Since most of my stuff is composite-cased these days, I have exactly one 3" and one 4" aluminum case, so I guess we're using those! The 4" is a 58" custom job, but I don't want to use the full 58" of propellant for this one because those loads are a pain to make and require buying two liner/casting sets. So, I'll buy one 48" stick of liner/casting tube, and space the rest with PVC as I've done frequently in the past. The 3" case is a shortened 6000ns case, around 5500ns, which will do fine in the top. Booster fin security isn't a concern at all, because it worked in single-stage configuration on Keep the Change and this one won't be going nearly as fast. The sustainer fins will be the biggest test of this concept to date, as second stages are notorious for having fin flutter issues (right, Jim Jarvis?), but to this end, perhaps it's a blessing in disguise that I lost my 7600ns case in Kansas last July. Oh yeah, and I'll make the propellant super slow as well.

Here are some parameters I've worked out in my head so far:

-Obviously, with a 58" booster motor and a 45" airframe available, it'll be a split-airframe design (no need to sleeve the whole motor anyway). I recently tweaked my go-to fin from the age-old three-fin clipped delta design to mirror the swept-back, four-fin design that all the cool cats are doing these days.
-Transition will be made out of a 4" ogive FWFG nosecone. While I'd love to use a 4" conical, I've heard that the internal coupler overlap is much shorter on these than the 1+ calibers on the ogive ones; with the whole success of the flight quite literally hinging on this joint, I'd rather be safe than sorry.
-While my only other two-stage flight (at Balls 2011) used head-end ignition with the staging electronics in the sustainer's nosecone, I'll probably have the staging electronics in the booster on this one. I want to use my trusty ARTS for staging, and setting one channel to stage and one channel to deploy the booster chute at apogee would seem to make sense.
-Upper stage will likely contain a Stratologger (for backup purposes) and a MARSA54. I recently came into possession of a Multitronix "Kate" unit, and probably won't be able to resist trying to squeeze Kate into the 3" nosecone to hear live how the flight is going, even though it's not the most efficient use of space. This allows me to use Kate for tracking with maybe a cheap old RF backup as opposed to flying my AIM Xtra.
-Will likely be tower-launched from my friend's tower.
-I've got lots more details and ideas in my head, and will be coming back to update this periodically (that's the plan, at least...)

-prophecy
 
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The sustainer fins will be the biggest test of this concept to date, as second stages are notorious for having fin flutter issues (right, Jim Jarvis?),

I did have a pretty much stock Quantum Leap many years ago that behaved like the USS Bakula, except that the fins actually failed. So, that can happen. My other failures are more likely couplers/airframes and not fins.

Are you still looking for that temporary pad we discussed?

Jim
 
I did have a pretty much stock Quantum Leap many years ago that behaved like the USS Bakula, except that the fins actually failed. So, that can happen. My other failures are more likely couplers/airframes and not fins.

Are you still looking for that temporary pad we discussed?

Jim

Yes, sir - Mat's tower doesn't have the capacity to handle the 5" project, so still need a pad to fly that one off of. Though I'd rather build this one with three fins, tailoring it to fit what's available so that this problem isn't repeated :)

-s
 
Do you have a picture of said cool cat fins? I'm working up a 54mm minimum diameter for Black Rock this summer. I decided that if I'm going to build it I might as well try to make it as slick as possible.

I recently tweaked my go-to fin from the age-old three-fin clipped delta design to mirror the swept-back, four-fin design that all the cool cats are doing these days.
 
Looks good Steve!
How exactly did you "come into possession" of Kate? :)
 
Do you have a picture of said cool cat fins? I'm working up a 54mm minimum diameter for Black Rock this summer. I decided that if I'm going to build it I might as well try to make it as slick as possible.
IMG_2724.jpg
Here's a snapshot I got of his 5" rocket that got grounded at BALLS. It has the fin design that he's talking about. Notice the blue sky right above us...
 
Cool Steve! :cool: Looking forward to reading along on this journey!

To clarify, you're planning on flying this in New Mexico? And planning on attending Balls this fall as well?

I'm hoping to dust off my 4" to 3" sometime this year with a plan to Black Rock.

-Eric-
 
Awesome, Eric! Glad to hear you're shaking off the AIM Xtra debacle and planning on getting back out there. I've had a pretty rough last couple of trips out there too, so hopefully we can both get back on track.

Yeah, the plan is to fly this one in NM in the spring before the prospective waiver runs out in June. Even though I live closer to BR now, it's still 28 hours one way, so I really can only make one trip per year. To that end, I think I'm going to do Aeronaut this year. The last couple of Balls have been bitten by weather issues which are apparently much more common in late September than in the summer; Aeronaut fits better with my work schedule; I've always liked the atmosphere of smaller launches; and all my friends have started making Aeronaut a tradition, so that's that. Would be awesome to see you out there at Aeronaut!

Wilson - my dad and I were standing next to the PA (and Vern Knowles) when Tom Rouse's 90k flight went up with Kate on board. I think he was sold at that point and was looking for a reason to buy it, so he got one as a joint present to himself and to me at Christmas.

Chris - have to give credit where credit is due - I'm lucky to hang around the likes of James G., Ryan, David, and others in the aerospace industry every now and again. When all their projects started using this fin shape and getting dramatically better altitudes than I'd been getting with the old-style clipped delta design, it was all an ad writer could do to follow suit. I'll never forget when James G. showed up to Balls with a motor identical to one I flew in my 4" Mongoose (a 17500 70/10) and got 51k (I got 34).

-prophecy
 
To that end, I think I'm going to do Aeronaut this year. The last couple of Balls have been bitten by weather issues which are apparently much more common in late September than in the summer; Aeronaut fits better with my work schedule; I've always liked the atmosphere of smaller launches; and all my friends have started making Aeronaut a tradition, so that's that. Would be awesome to see you out there at Aeronaut!

-prophecy

That is exactly the launch I am trying to attend this year! Hope to see you there, sir!

-Eric-
 
Whee, progress! Strange day at work led to me needing to clear my head for a bit - this was the result:

IMG_20150128_172230183.jpg

Going to try to snowball this momentum and get some fins cut tonight.

-s
 
Wow, 50% is a huge improvement. Sorry, who is James G. I've been out of the loop for 14 of the last 15 years.

Chris - have to give credit where credit is due - I'm lucky to hang around the likes of James G., Ryan, David, and others in the aerospace industry every now and again. When all their projects started using this fin shape and getting dramatically better altitudes than I'd been getting with the old-style clipped delta design, it was all an ad writer could do to follow suit. I'll never forget when James G. showed up to Balls with a motor identical to one I flew in my 4" Mongoose (a 17500 70/10) and got 51k (I got 34).

-prophecy
 
Wilson - my dad and I were standing next to the PA (and Vern Knowles) when Tom Rouse's 90k flight went up with Kate on board. I think he was sold at that point and was looking for a reason to buy it, so he got one as a joint present to himself and to me at Christmas.

Chris - have to give credit where credit is due - I'm lucky to hang around the likes of James G., Ryan, David, and others in the aerospace industry every now and again. When all their projects started using this fin shape and getting dramatically better altitudes than I'd been getting with the old-style clipped delta design, it was all an ad writer could do to follow suit. I'll never forget when James G. showed up to Balls with a motor identical to one I flew in my 4" Mongoose (a 17500 70/10) and got 51k (I got 34).

-prophecy
Very nice. :) As for the fin design - hey, you know nothing we do in rocketry is original!

That is exactly the launch I am trying to attend this year! Hope to see you there, sir!

-Eric-
Sweet! I'm planning to attend Aeronaut as well for pretty much all the reasons Steve outlined. (I'm lucky to live 9 hours away...) Eric - it would be great to shake your hand then!
 
The blowing off steam experiment got me through tracing all fins onto the G10, changing the blade in the Harbor Freight bandsaw (for those playing along at home, that is a b and a half), rough cutting the fins, and edging/beveling one of the upper stage fins before I hit a wall.

You'll note two things; 1.) only three fins of each size. I prefer three fin designs, and had been on the fence before realizing that I only had enough material for a three fin design. Love when decisions are made easy! 2.) only one booster fin is traced - I didn't have access to a straightedge longer than 12", which left me SOL for connecting the dots on the booster fins (even for the resourceful-minded - I stopped short of using the edge of the bathroom mirror). Figured I'd get one cut and edged and then just trace it as a template for the other two.

Slow and steady wins the race (not my normal MO, so I'll take it here).

-s

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Got some more done this weekend. Edged and beveled all the fins (life lesson #46 - getting a perfect edge on a 14" root is a b!tch on a 12" sander). Opened up the box with my 4" airframe, which was a cutoff from a longer piece, and spent a few hours setting up the 4" table on the bench sander with three axes of perfectly square to true up the ends of the tube. Of course this setup is only good for as square as you are able to hold a 45" tube on a 4" table. The combination of my OCD perfectionism and my refusal to pay for fancy tools leaves us with an uphill battle most of the time, but modifying said tools and lots and lots of time and experience in the crappy tools world and we make it work.

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We then mark and cut 1/8" deep notches for epoxy rivets, and then mask off 1" on each side for the patent pending belt sander rump surface prep:

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And then the Superbowl started. Next step is to rough up the tube, mark the fin locations, and then get to my favorite step of rocket building - tacking fins.

Biggest random victory of the night was discovering that the nosecone from the 4" composite case project - which I was certain was a true 4" nosecone - is actually 3.9" OD and fits the tube. This nosecone came in on its own from 40,000' at Airfest and we miraculously found it by walking the line between the launch pad and where the electronics were found. This saves me from having to buy and then promptly hack up a shiny new nosecone for the transition. Exciting.

Not much progress, but dealing with crappy tools and OCD this was about 9 hours of work which is a pretty solid chunk of the weekend. And we've barely scratched the surface (ha). Stay tuned.
 
Steve,
Glad you're going to Aeronaut. We should have a really good bunch of flights this year. I'm hoping to break 60K and M3.5 and there's a group trying to break 200k (crossing my fingers for that one!) From what I've heard this year will be better then Balls in terms of performance flights. :grin:
Looking forward to seeing you out on the playa.

:pop:

Alex
 
Yeah, it seems like among my friend group the migration to the summer launches has been slow but steady, probably because the last couple of Balls have been bitten by bad weather. Look forward to seeing you there, Alex. Assuming I'm able to get this thing off the ground in New Mexico along with last year's Balls project and Mat's project from last year, the plan is for Mat and I to have a 6" case-bonded motor. This plan diminishes with each passing day that we're still logjammed with projects waiting for New Mexico, but I still have hopes. Worse case, I'll slap some layups on this and load it full up with 54" of 98mm HoneyBadger in the bottom and a 7600 in the top.

Last night I spurned all responsibility and spent six hours on rocket stuff on a work night. Can't be doing that too often, but once it finally starts looking like a rocket, it's hard to stop. I've also always had this weird thing about wanting to get fillets on ASAP after the fins were tacked so they aren't accidentally knocked off or out of place somehow. So:

Fins will be mounted starting at +2.5", and we'll rough up .75" above and below, so figuring a 14" root...we'll rough from 1.75" from the bottom to 16.5" from the bottom. Marked off with tape, got in a forearm workout with 60 grit, and then used the patent pending "waves on the beach" crosshatching technique with a hacksaw blade (switched from 24TPI to 32TPI - be happy, flynfrog ;)). This name came from the construction of Keep the Change in the summer of 2013 - I built it during a stopover at my parents' house on Long Island sound, and roughed up the tube in a lawn chair on the dock during sunset, watching the waves roll in, timing each strike of the hacksaw blade with the waves (and the pattern kinda looked like waves, too). Build threads are pretty pointless without random asides. Man do I miss that spot.

IMG_20150203_192641579.jpg

Then, we took our handy dandy OpenRocket fin template (a major upgrade from a piece of tape with marks every third of the circumference) and butted it up against a ring of tape marking the 2.5" line where the fins were to be mounted. We marked a little dot on the tape (Sharpie is hard to see on black tube), and then ran a pencil line with an angle iron through the center of each dot and up the tube.

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Then it's gametime! And a 1:

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We of course used our handy dandy popsicle stick "faux slot" technique here, also patent pending. No fancy CNC jigs or templates here, we rely on our own (lack of) competence:

IMG_20150203_211346965.jpg

And a 2:

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And a 3:

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Then we must begin the fillets immediately, per quota. As previously mentioned, this is the first of these builds to use Rocketpoxy as opposed to Proline 4500 - initial reaction is that they're quite different products even though they occupy the same space in the market. It was so thick it took two trusty popsicle sticks to mix it, as opposed to Proline 4500 which is quite runny. I worry that the penetration won't be quite as good, but it was way more workable, and we have our first set of fillets!

IMG_20150203_234958201.jpg

Time for bed. Rough day at work on the way today for sure but so satisfied to have broken the back of this.
 
With rocketpoxy fillets I typically lay a small bead down the length as soon as it's mixed and at it's runniest to get right into the corner of the joint and eliminate air bubbles. Then I'll add a thicker bead a little later and shape the fillet.
 
Do you have a picture of said cool cat fins?

After Kyle Cornelius's L-2050 mach~3 flight at Airfest last year.
I'd love to see this on top of a 2-stage. Hello mach 4 :)

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Hey Steve
 
Glad to hear you're shaking off the AIM Xtra debacle and planning on getting back out there.

Anybody care to elaborate on this? Was it user error or problems with the device itself?
 
Anybody care to elaborate on this? Was it user error or problems with the device itself?

Derek: documented in my Balls adventure thread here: https://www.rocketryforum.com/showthread.php?56834-Balls-22-Projects&highlight=balls+22+projects

More specifically starting at post #127 starting here: https://www.rocketryforum.com/showthread.php?56834-Balls-22-Projects&p=615642#post615642

It appears that Entacore has eliminated the issue by offering firmware updated; I have not flown the unit to verify this.

Mr. Prophecy...I am reading along with great interest by the way! Looking good. I too have moved more in the direction of RocketPoxy than Proline 4500. I have flown Rocketpoxy fillets to M2.3 without issue; haven't pushed things past that point yet however....good stuff, like you said has its own interesting workability characteristics. Build on, my friend!

-Eric-
 
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Derek: documented in my Balls adventure thread here: https://www.rocketryforum.com/showthread.php?56834-Balls-22-Projects&highlight=balls+22+projects

More specifically starting at post #127 starting here: https://www.rocketryforum.com/showthread.php?56834-Balls-22-Projects&p=615642#post615642

It appears that Entacore has eliminated the issue by offering firmware updated; I have not flown the unit to verify this.

Mr. Prophecy...I am reading along with great interest by the way! Looking good. I too have moved more in the direction of RocketPoxy than Proline 4500. I have flown Rocketpoxy fillets to M2.3 without issue; haven't pushed things past that point yet however....good stuff, like you said has its own interesting workability characteristics. Build on, my friend!

-Eric-

Hi Derek,

In addition to Eric's issue, we flew an AIM Xtra in our 4" composite cased project at Airfest, which mysteriously experienced a very premature deployment. We had it set to "apogee - accel only," and after reading of others' similar issues on the forum, came to the conclusion that this led to the inaccuracy of detecting apogee (even though older units like the GWiz LCDs and ARTS used accel only for apogee and never had a problem - who knows). For our 5" composite cased flight we changed the setting to Kalman filter - combo for apogee, which we hope corrects the problem - but it's been grounded since Balls, so we still don't know whether it will correct the problem or not. I must say, I am somewhat uneasy about flying the AIM Xtra at all, but with $420 sunk into it (and it's a snazzy little unit), what are my options? To buy a Telemetrum? Gary at OffWeGo Rocketry is a good guy, but with the product being of international origin and direct communication with the manufacturer impossible, resolving problems is somewhat challenging and leaves me with an uneasy feeling of things getting "lost in translation."

Eric,

Thank you sir! Going to try and sneak home during my lunch break and get on the second set of fillets.

There's been a slight change of plans in this project; with New Mexico still in limbo, and my dad texting me weekly to see if I've used the Kate unit he bought at Christmas, and my friend Mat's work schedule opening up for the March launch in Argonia, and Manny twisting my arm to make the trip, it appears that plans are in motion to try and make a trip up there. Since I still don't have the 3" parts from littlemisterbig and couldn't fly the two stage stack under a 50k' waiver anyway, I think the most logical option is to fly the 4" single stage, with Kate and my BigRedBee and the age-old RF tracker (I am not losing another rocket in the Bermuda Triangle - Argonia version. Just not gonna happen), with my dad in attendance. If he's going to hop a flight halfway across the country, I'd better have it all ready. To this end, I bit the bullet and paid full price for a nosecone yesterday, and will go ahead and finish this out as a single stage for now (just like Alpine Style. I swore this wouldn't happen again).

Stay tuned...

-s
 
Following along Steve, cool project. I hope to make it out to the playa again this year.
 
... I think the most logical option is to fly the 4" single stage, with Kate and my BigRedBee and the age-old RF tracker (I am not losing another rocket in the Bermuda Triangle - Argonia version. Just not gonna happen), with my dad in attendance. ...

Do you plan to fly with Kate, BRB and the RF tracker all in the nosecone together? Just wondering if there will be any compatibility issues or interference between them.
 
Do you plan to fly with Kate, BRB and the RF tracker all in the nosecone together? Just wondering if there will be any compatibility issues or interference between them.

Hey Vern,

Will probably not end up having the guts to put that much tracking money in one basket - and will likely go with Kate and the RF tracker (222.XXX) Any insight as to whether this will cause an issue?

Thanks,

Steve H.
 
Hey Vern,
Will probably not end up having the guts to put that much tracking money in one basket - and will likely go with Kate and the RF tracker (222.XXX) Any insight as to whether this will cause an issue?
Thanks,
Steve H.


That should be okay. Kate has been flown many times with ~220 MHz RF trackers in the nosecone without any issues. I suggest keeping as much separation between the two antennas as is practical. Anytime an antenna has something conductive (like another antenna) placed along side it, then the antenna can potentially become de-tuned and the radiation pattern can also be distorted. Which means reception would not be as good. What I have done myself is duct tape the RF tracker antenna to the inside surface of the nosecone to keep it as far away from Kate's antenna as possible.
 
Got another set of fillets on last night - I swear this isn't the same picture...

Also got curative, catalyst, and motor hardware ordered for the Mar. 14 flight. Get closer each day.

IMG_20150205_185036808_HDR.jpg
 
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