Jay's Tau Zero A-C Launch

[Tau Zero]

Today I drove 70 miles one way to fly with the Tripoli Idaho guys at their summer flight range west of Fairfield, Idaho. The first of my rockets off of the low power (or "Estes") pads was my Tau Zero on an A8-3. Taping the motor in made all the difference on this flight, and the TZ hit about 300 feet before coming down on a streamer. The Tripoli Idaho crew offered several noises of approval for this one.

I slapped a C6-5 into my low-power (18mm) Sirius Rocketry Interrogator, and *that* impressed the gathered high-power rocketeers. The Interrogator made it to about 550 feet and nosed over for a picture-perfect ejection and recovery. (Now I'll *have* to try the mid-power 24mm Interrogator on some D's. ;-D)

I sent up my Prometheus with newly extended elastic shock cord on an A8-3. Nice performance to about 225 feet, with a good recovery.

Determined to test my Tau Zero on the entire A through C motor spectrum, I inserted a B6-4 motor and let it fly. The launch director asked me, "Did you notice it was a little less stable on that B motor?" I didn't, but the Tau Zero made it to about 600 feet, blew the streamer, and landed gently in the alfalfa field. (For you city dwellers, that's what us farm boys cut up and turn into hay. ;-D )

The Prometheus tore off the pad on B6-4, arrowed to about 550 feet, and ejected the chute shortly after apogee. Unfortunately, on this flight, I discovered a disturbing corollary to Bill Eichelberger's dreaded "Launch Fever." A teenage boy had been running like mad after rockets even before they'd landed. Partially as a joke, I sent him out to recover the Prometheus. This is when I found out (all over again) about "Inexperienced Tracker Syndrome." (I attribute the loss of my original 1.36X Estes Wolverine two years ago at the same flight range to this particular malady.)

In brief, the tracker went *way* too far, and even though I followed up his wake with a more sweeping eye, my original prototype for the "Prometheus" is now destined to become part of the next cutting of cattle feed. :mad: :o In other words, "Eez lost." And along with a perfectly good 12" ripstop nylon parachute, too.

The Tau Zero needed one final flight on a C6-5 to bring my launch day to a close. RockSim had estimated its altitude at more than 1100 feet, so I was ready for a lengthy recovery walk. Unfortunately, my wife noticed that the wind was blowing harder than it had been, and since she and my girls were ready to leave after 2.5 hours, she prayed, "God, don't let Jay have to walk a long ways for this rocket."

The Almighty was listening, and the Tau Zero pinwheeled off the pad, made it to an altitude of roughly 30 to 50 feet above ground level, and hit the gravel road about six feet in front of my car. The ejection charge blew the streamer, but a bit late. (Reminder to self: When taking wife to launches, remind her not to invoke Higher Powers to induce undesireable outcomes regarding rocket flights.)

Actually, this particular design does fine on A motors, but B and definitely C motors will require some sort of nose weight. (And I'm not particularly keen on extending the main body tube from 9" to 12", but that *may* be part of the solution.)

Here are pics of the rockets in question: Tau Zero and Prometheus (http://forums.rocketshoppe.com/showpost.php?p=8227&postcount=10) and Interrogator (http://forums.rocketshoppe.com/showpost.php?p=8228&postcount=11) from a previous thread of mine.


SUMMARY:

Interrogator on C6-5: *Smokin'!*
Prometheus on A8-3, B6-4: Unexpectedly high performance. Get yourself a professional tracker for B flights and above.
Tau Zero: Great on A8-3, wiggly on B6-4, performs terrifying cartwheels on a C6-5.

(Now I'm wondering how the heck Bill Eichelberger's TZ flights were so good on a B6-6 and C6-7, respectively. Okay, maybe it's because there wasn't anybody lurking nearby who was in cahoots with beings from a higher plane of existence.)

At least I remembered to put sunscreen on my face, neck, ears, and knees. My arms are another story, though. :eek:

Then I came home to see Scott Goebel's smiling face on my first official issue of Sport Rocketry. :D


All in all, a good day.

[James Pierson]

Jay, Sorry to hear about the Prometheus as cattle feed. Been there and done that as well. Also about the Tau Zero, you have a few options as far as C flights go : larger ring fin, increase outter fin length from body, lengthen rocket body, add tailcone, increase fin number. Nose wieght is a double edged sword, increases stability for C flights yes, but will reduce altitude on smaller motors. Sounds like you get to play with Rocksim a bit. :D

Hope this helps, JP

James Pierson
NAR# 77907

[Tau Zero]

Photos please.Click on the links (the underlined rocket names). Nothing new from today except for smoke trails. :eek: :rolleyes: :o

Thanks for the "encouraging words," though. ;) :D


about the Tau Zero, you have a few options as far as C flights go : lengthen rocket bodyI'll start with this one. :(

Cheers,

[Tau Zero]

needed one final flight on a C6-5 to bring my launch day to a close. The Tau Zero pinwheeled off the pad, made it to an altitude of roughly 30 to 50 feet above ground level, and hit the gravel road about six feet in front of my car.Okay, kids, here's what I learned about RockSim and the real world. :o

After going back to my Bruce Levison-tweaked Tau Zero file, I compiled the following figures on stability. I lengthened the 9" long ST-7 body tube to 12" just for contrast:


Tau Zero 12" (ST-7120 body tube)

Motor / Stability factor (CG ahead of CP)

Empty -- 5.87 calibers
A8-3 -- 2.54
B4-4 -- 2.26
B6-4 -- 2.33
C6-5 -- 1.85 :cool:


Tau Zero 9" (ST-790 body tube)

Motor / Stability factor (CG ahead of CP)

Empty -- 4.08 calibers
A8-3 -- 1.39
B4-4 -- 1.17
B6-4 -- 1.23
C6-5 -- 0.86 Marginal :eek:


*There's* my problem right there! (Funny how I didn't notice it in the computer until my real world model did cartwheels across the flight range.)

So it looks like my Tau Zero Prototype II will have a slightly longer main tube than the original. :o ;) :cool:


Cheers,

[andrew scott]

o no i just order the parts for tau zero from semroc !!! :eek: ;)
ok i just go and order a BT 712 :p

[CPMcGraw]

Okay, kids, here's what I learned about RockSim and the real world. :o Tau Zero 9" (ST-790 body tube)

Motor / Stability factor (CG ahead of CP)

Empty -- 4.08 calibers
A8-3 -- 1.39
B4-4 -- 1.17
B6-4 -- 1.23
C6-5 -- 0.86 Marginal :eek:

Cheers,

Jay,

On one of my revision files, I got a 1.03 margin for the C6-3, so we're both seeing the same thing happening.

Try increasing the length to 10" instead of 12". The extra 1" should give you more than enough margin, and not alter the appearance much.

BTW, using the 10" length my motor selection is as follows:

A8-3 -- 2.05 -- 147' -- 27 FPS
B4-2 -- 1.81 -- 249' -- 11 FPS
B6-2 -- 1.87 -- 242' -- 13 FPS
C6-3 -- 1.47 -- 444' -- 18 FPS

See the attached RS file for additional data...

Addendum: Yes, I see the discrepancy in the altitudes. I need to look at all of the variations we came up with to see what the averages are...

[A Fish Named Wallyum]

(Now I'm wondering how the heck Bill Eichelberger's TZ flights were so good on a B6-6 and C6-7, respectively. Okay, maybe it's because there wasn't anybody lurking nearby who was in cahoots with beings from a higher plane of existence.)

Yeah, that's about it. Hanging with heathens will guarantee stability every time. :D

[Tau Zero]

BTW, using the 10" length my motor selection is as follows:

A8-3 -- 2.05 -- 147' -- 27 FPS
B4-2 -- 1.81 -- 249' -- 11 FPS
B6-2 -- 1.87 -- 242' -- 13 FPS
C6-3 -- 1.47 -- 444' -- 18 FPSCraig,

That's an excellent layout to include the CG/CP differential (stability) figure. :cool:

On my initial "Rebuild" file (the one I consulted you on), I remember that all of the delays were 2 seconds, and the altitudes were around 100 feet. :eek:


Here's what I get using the Bruce Levison-tweaked file:

+++

Tau Zero 10"

Motor / Calibers / Max. Alt. / Dv

Empty - 4.67
A8-3 -- 1.77 -- 332' -- 22 FPS
B4-4 -- 1.52 -- 645' -- 20 FPS
B6-4 -- 1.59 -- 645' -- 24 FPS
C6-5 -- 1.19 -- 1176' -- 8 FPS


Tau Zero 9"

Empty - 4.08
A8-3 -- 1.39 -- 314' -- 20 FPS
B4-4 -- 1.17 -- 632' -- 22 FPS
B6-4 -- 1.23 -- 632' -- 25 FPS -- Wiggly! :confused:
C6-5 -- 0.86 -- [1180' -- 12 FPS] -- Cartwheels 30' high!!! :mad:


Tau Zero 12"

Empty - 5.87
A8-3 -- 2.54 -- 319' -- 20 FPS
B4-4 -- 2.26 -- 629' -- 20 FPS
B6-4 -- 2.33 -- 630' -- 23 FPS
C6-5 -- 1.85 -- 1160' -- 9 FPS

+++


I suppose that using comprehensive R&D methods would entail building a Tau Zero with a 12" ST-7, flying it on C engines, and gradually trimming back the length to 10" to see how it performs.

Last night, I kept wondering if I should add some detailing to the front end of the ST-712 to break up its (now seemingly) excessive length. I'm still thinking. (Hmm...)

Anyway, thanks for the feedback.

[CPMcGraw]

Craig,

That's an excellent layout to include the CG/CP differential (stability) figure. :cool:

I think I'll start including it in all future design posts. Thanks.

I suppose that using comprehensive R&D methods would entail building a Tau Zero with a 12" ST-7, flying it on C engines, and gradually trimming back the length to 10" to see how it performs.

I had not started the construction of my TZ when you posted your tale of woe, so I located a spare 12" ST-7 and cut it back to 10". My TZ is now completed, pre-prime, with the ring and outer fins not glued in place. I'll try to get it primed tomorrow and glued together by Wednesday for a flight next weekend.

On your 9" prototype, just take a 1", 2" and 3" section of ST-7 and glue into each an HTC-7 coupler. Just run the shock chord through these to the NC and slip them into place. Now you can test out three combinations of length to see which works best.

Perhaps this is real reason why Carl hasn't set up a kit yet -- no actual flight data to prove the RockSim predictions. Maybe it's a good thing you've found this out early...

One additional note, concerning any kit that might be released. This design really needs to have a set of fin alignment guides laser-cut to get the angles correct. Even with a cardstock guide I didn't get one of those inner fins spot-on, and it shows. Carl's 0.05" fiberboard material would be much better. You need two guides for each set, so that you get the same angle along the full length of each fin.

[CPMcGraw]

o no i just order the parts for tau zero from semroc !!! :eek: ;)
ok i just go and order a BT 712 :p

Andrew,

Don't worry too much about those parts, because Jay and Bill E. and I are actively working to test this design and find out what really happened. It just goes to show, you can't fully trust a computer to design something fool-proof...

Remember this passage:

"A common mistake that people make when trying to design something completely foolproof was to underestimate the ingenuity of complete fools."

Remember this one, as well:

"They're not complete idiots... Some parts are missing..."

Both of these statements occasionally apply to us here on the forum... :D

[Tau Zero]

I had not started the construction of my TZ when you posted your tale of woe, so I located a spare 12" ST-7 and cut it back to 10". My TZ is now completed, pre-prime, with the ring and outer fins not glued in place. I'll try to get it primed tomorrow and glued together by Wednesday for a flight next weekend. :cool:


On your 9" prototype, just take a 1", 2" and 3" section of ST-7 and glue into each an HTC-7 coupler. Just run the shock cord through these to the NC and slip them into place. Now you can test out three combinations of length to see which works best.Good suggestion! I've already decided my original 9" TZ is going to be for A and maybe 1/2A demonstration flights.


Perhaps this is real reason why Carl hasn't set up a kit yet -- no actual flight data to prove the RockSim predictions. Maybe it's a good thing you've found this out early...That, and he's still waiting for me to pound out the instructions... :o ...which I hope to get to after the flight-testing and preliminary review.

Personally, I think it would be irresponsible for me to foist a design that "Looks Cool, But Doesn't Fly Worth Beans" (*That's* a terrible tag line) on the rest of you. So thanks for the specific feedback!


One additional note, concerning any kit that might be released. This design really needs to have a set of fin alignment guides laser-cut to get the angles correct. Even with a cardstock guide I didn't get one of those inner fins spot-on, and it shows. Carl's 0.05" fiberboard material would be much better. You need two guides for each set, so that you get the same angle along the full length of each fin.Could you sketch out an example of what you mean? I'm having a little trouble visualizing it.

Okay, a *lot.* :rolleyes: ;)


o no i just order the parts for tau zero from semroc !!! ok i just go and order a BT 712Andrew,

As Craig mentioned, we're working on "getting it right" with my Tau Zero design. So just keep checking in here so you can find out *exactly* what works! :D


Thanks, and cheers,

[A Fish Named Wallyum]

As Craig mentioned, we're working on "getting it right" with my Tau Zero design. So just keep checking in here so you can find out *exactly* what works! :D


A C6-7. That's what works in mine.
You can quote me on that. ;)

[Tau Zero]

A C6-7. That's what works in mine.
You can quote me on that. ;)And I can't figure out why it did. Say, you never did tell me if you used a parachute or a streamer on yours.

[A Fish Named Wallyum]

And I can't figure out why it did. Say, you never did tell me if you used a parachute or a streamer on yours.

Wall E. Coyote - SUPER genius
I used a streamer with only Kevlar for a shock cord and a decent size screw eye. :confused:

[Tau Zero]

Wall E. Coyote - SUPER geniusWell, okay, I *should* have remembered *that!* :rolleyes:


I used a streamer with only Kevlar for a shock cord and a decent size screw eye. :confused:One of Carl's? I used an SE-10, but maybe I should bump it up to an SE-12 or even SE-14 (http://www.semroc.com/Store/scripts/prodList.asp?idCategory=71)! :D ;)


You *are* a freakin' SUPER Genius, at that! :eek: :cool:


Cheers,

[A Fish Named Wallyum]

Well, okay, I *should* have remembered *that!* :rolleyes:


One of Carl's? I used an SE-10, but maybe I should bump it up to an SE-12 or even SE-14 (http://www.semroc.com/Store/scripts/prodList.asp?idCategory=71)! :D ;)


You *are* a freakin' SUPER Genius, at that! :eek: :cool:


Cheers,

The screw eye was one of an assortment that I bought at Lowe's.
As for the flight, I think I was lucky. We'll see this weekend. If conditions are right, I'm going to try it again.

[Tau Zero]

The screw eye was one of an assortment that I bought at Lowe's.Do me a favor: Measure the outside diameter of the screw eye, and post a picture of it here.


As for the flight, I think I was lucky. We'll see this weekend. If conditions are right, I'm going to try it again.Your "lucky" variable may be a bigger, heavier screw eye.

Keep me posted!


Cheers,

[Tau Zero]

I used an SE-10, but maybe I should bump it up to an SE-12 or even SE-14 (http://www.semroc.com/Store/scripts/prodList.asp?idCategory=71)!Hey, Carl!

How big is the outer diameter for the eye of your SE-14? Will it fit comfortably inside an ST-7?

And how much does it weigh? (I need to add it to my RockSim data file.)


Thanks, as always, and cheers,

[Carl@Semroc]

Hi Jay!

You prodded me into doing something I should have already done!

SE-10 .40" OD .95" Long 1.0g
SE-12 .48" OD 1.12" Long 1.9g
SE-14 .53" OD 1.47" Long 5.0g

All fit the ST-7. The SE-14 is to large for ST-5. We use the SE-14 to add extra weight on several kits. At .176 oz., it is slightly heaver than the Estes NCW-1 (.12 oz.) and their small screw eye (.03 oz) combination (without the soft lead hazard.)

[Tau Zero]

Good news! Thanks to Carl's information on Semroc screw eyes, I think I've solved the Tau Zero C6-5 instability problem I had! (And which Bill *didn't* have, apparently thanks to a beefier screw eye from Lowe's!)

I got the following RockSim results from a version *with NO screw eye!*Tau Zero 9" (ST-790 body tube)

Motor / Calibers / Max. Alt. / Dv

+++

Without Screw Eye

Empty - 4.08
A8-3 -- 1.39 -- 314' -- 20 FPS
B4-4 -- 1.17 -- 632' -- 22 FPS
B6-4 -- 1.23 -- 632' -- 25 FPS -- Wiggly! :confused:
C6-5 -- 0.86 Marginal [1180' -- 12 FPS] -- Cartwheels 30' high!With SE-10 Screw Eye

Empty - 4.17
A8-3 -- 1.49 -- 335' -- 23 FPS
B4-4 -- 1.26 -- 650' -- 21 FPS
B6-4 -- 1.32 -- 650' -- 24 FPS -- Wiggly! :confused:
C6-5 -- 0.95 Marginal [1185' -- 8 FPS]


With SE-14 Screw Eye (!)

Empty - 4.77
A8-3 -- 2.13 -- 300' -- 18 FPS
B4-4 -- 1.90 -- 619' -- 22 FPS
B6-4 -- 1.96 -- 622' -- 26 FPS
C6-5 -- 1.56 -- 1175' -- 14 FPS (*Not* marginal!) :eek: :D :cool:

+++


So there I go! I just need to get some SE-14's with my next Semroc order!


Nose weight is a double edged sword, increases stability for C flights yes, but will reduce altitude on smaller motors. Losing 10% of altitude on an A flight in exchange for *not* cartwheeling on a C is a sacrifice I'm willing to make. :D


Sounds like you get to play with Rocksim a bit.Indeed. ;)


Cheers,

[andrew scott]

Jay, Craig, Bill

I have been planning to build tau zero for sum time, so finding that it has instability problem is no big deal.
Os i order the parts and body tubes, rocket Kits from semroc

Seeing that is going be my first (semroc?) non estes kit (the Estes kit are starting go down hill):mad: (Estes space ship one sucks, and 36DD? ok ho the designer at Estes ho go to hootes, just jugging or is joking). :p

Well if I don't include all my own design and all the flis kits I have.:)

This is going to be fun rocket to build and love to see semroc make it one of there kits. (BIG HINT)
Next on my build list will be Prometheus.:cool:

[JRThro]

Good news! Thanks to Carl's information on Semroc screw eyes, I think I've solved the Tau Zero C6-5 instability problem I had! (And which Bill *didn't* have, apparently thanks to a beefier screw eye from Lowe's!)

I got the following RockSim results from a version *with NO screw eye!*With SE-10 Screw Eye

Empty - 4.17
A8-3 -- 1.49 -- 335' -- 23 FPS
B4-4 -- 1.26 -- 650' -- 21 FPS
B6-4 -- 1.32 -- 650' -- 24 FPS -- Wiggly! :confused:
C6-5 -- 0.95 Marginal [1185' -- 8 FPS]


With SE-14 Screw Eye (!)

Empty - 4.77
A8-3 -- 2.13 -- 300' -- 18 FPS
B4-4 -- 1.90 -- 619' -- 22 FPS
B6-4 -- 1.96 -- 622' -- 26 FPS
C6-5 -- 1.56 -- 1175' -- 14 FPS (*Not* marginal!) :eek: :D :cool:

But let's keep in mind, please, that 0.86 or 0.95 calibers of stability *are* stable designs, just not quite as stable as 1.56 calibers. A design that Rocksim calls marginally stable *is* stable. A design with 0.86 calibers of stability will *not* pinwheel off the launch pad.

Whether or not the real rocket, once it's built, has the same margin of stability as that predicted by Rocksim is the real issue. And apparently Jay's *real* Tau Zero was not as stable as Rocksim predicted it would be.

(Jay, I don't recall if you're using the Rocksim or Barrowman stability calcs. If I recall correctly, the Barrowman calcs are generally more conservative than the Rocksim ones. That is, the Barrowman calcs generally say a design is at least somewhat less stable than the Rocksim stability calcs do.)

[Tau Zero]

This is going to be fun rocket to build and love to see semroc make it one of there kits. (BIG HINT)(serious look) And did you *vote* for it? :rolleyes: ;) :D


Next on my build list will be Prometheus.:cool:Make sure the "exposed" part of your elastic shock cord is at least 3 feet long. (Or maybe a meter. :eek: :rolleyes: ) And get ready, because it will *rip* off the pad. (Get yourself an extra-good tracker.)


Cheers,

[Tau Zero]

A design with 0.86 calibers of stability will *not* pinwheel off the launch pad. [SNIP] Whether or not the real rocket, once it's built, has the same margin of stability as that predicted by Rocksim is the real issue. And apparently Jay's *real* Tau Zero was not as stable as Rocksim predicted it would be.And I thought *I* was relatively stable. :confused: To complicate the issue, a few onlookers occasionally question Bill's stability (I know how that feels), but *his* Tau Zero flew just fine on a C6-7. :o

I just got done ordering some bigger screw eyes (SE-14) as well as nose weights (WL-7) from Semroc. The Tau Zero has taken more test flights than I initially expected, but I think the "real world" experience will pay off for the rest of you who decide to build one. ;) :D


(Jay, I don't recall if you're using the Rocksim or Barrowman stability calcs. If I recall correctly, the Barrowman calcs are generally more conservative than the Rocksim ones.)Indeed. I'm using the RockSim calculations. (Because of the tube fin, and all that.)

I ordered the SLS 175% upscale of the BC-760 nose cone, too. :eek: :cool:


Cheers,

[A Fish Named Wallyum]

(serious look) And did you *vote* for it? :rolleyes: ;) :D


Apparently I've already voted for it because when I tried tonight it wouldn't count my vote.
I also noticed that someone has been voting for Semroc to produce currently available Quest kits. The Big Betty even has six votes. Isn't that kinda stupid?

[Tau Zero]

Apparently I've already voted for it because when I tried tonight it wouldn't count my vote.I figured you already had. If I remember correctly, you can only vote once per computer. (Or something like that. :confused: :o )

*Somebody* voted today, though. It only had 23 votes earlier while I was at work this afternoon.


I also noticed that someone has been voting for Semroc to produce currently available Quest kits. The Big Betty even has six votes. Isn't that kinda stupid?Yeah, I find it kind of odd that "currently available" kits are on Carl's list. :confused: Hmm...


Thinking (superficially) deep thoughts,

[CPMcGraw]

I figured you already had. If I remember correctly, you can only vote once per computer. (Or something like that. :confused: :o )

*Somebody* voted today, though. It only had 23 votes earlier while I was at work this afternoon.

:rolleyes: Hmmnn :p hmmnn ;) hmmnn :o ...

[CPMcGraw]

Yeah, I find it kind of odd that "currently available" kits are on Carl's list. :confused: Hmm...

Makes perfect sense to me. They're just saying Carl could package a better kit version with better-quality components than Quest has been doing, even if the price might be a little higher. Think about Quest's parts compared to Carl's...

[A Fish Named Wallyum]

Makes perfect sense to me. They're just saying Carl could package a better kit version with better-quality components than Quest has been doing, even if the price might be a little higher. Think about Quest's parts compared to Carl's...

Think about the designs.

[Tau Zero]

:rolleyes: Hmmnn :p hmmnn ;) hmmnn :o ...Good news, Craig. This makes you Somebody. :rolleyes: ;) :D


Cheers,

--Jay

[Tau Zero]

I think I've solved the Tau Zero C6-5 instability problem I had!
[SNIP]
I just need to get some SE-14's with my next Semroc order!I ordered a bunch of parts *early* last Thursday, and the box showed up on my desk at work today. :D

I just replaced the Tau Zero's SE-10 with an SE-14. *Now* when I heft the TZ, it's pretty beefy. :eek: :cool:

I also ordered some "washer weights," as well. RockSim says with just the bigger screw eye (5 times the original weight), the stability margin is 1.56 calibers on a C6-5. Adding 1 and 2 washer weights as well increases the calibers to 1.95 and 2.30, respectively.

I hope to put the Tau Zero up again on a C6-5 at next month's Tripoli Idaho launch. I may also prep a second nose cone with 2 washer weights and an SE-14 screw eye, and test-fly *that* configuration just for good measure. :p


Cheers,

[JRThro]

I ordered a bunch of parts *early* last Thursday, and the box showed up on my desk at work today. :D

I just replaced the Tau Zero's SE-10 with an SE-14. *Now* when I heft the TZ, it's pretty beefy. :eek: :cool:

I also ordered some "washer weights," as well. RockSim says with just the bigger screw eye (5 times the original weight), the stability margin is 1.56 calibers on a C6-5. Adding 1 and 2 washer weights as well increases the calibers to 1.95 and 2.30, respectively.

I hope to put the Tau Zero up again on a C6-5 at next month's Tripoli Idaho launch. I may also prep a second nose cone with 2 washer weights and an SE-14 screw eye, and test-fly *that* configuration just for good measure. :p


Cheers,
Jay, so you're adding weight without lengthening the body, is that right? And the 1.56 calibers compares directly to the 0.86 that you had originally? Sounds good!

[A Fish Named Wallyum]

Jay, so you're adding weight without lengthening the body, is that right?

So what's the big deal? I've been doing that for years. :rolleyes:

[Tau Zero]

Jay, so you're adding weight without lengthening the body, is that right? And the 1.56 calibers compares directly to the 0.86 that you had originally?Yes! Actually, to the 0.95 calibers *with* the SE-10 screw eye (which I forgot in the initial sim).


Sounds good!Yeah. I was bummed that I might have to make the body tube longer and make the shape "more uncooler" than it was originally. :( :mad:


So what's the big deal? I've been doing that for years. :rolleyes: (Stage whisper) "To the *rocket,* Bill! Not to *us!*" :eek: ;) :D


Cheers,

[JRThro]

So what's the big deal? I've been doing that for years. :rolleyes:
You and me both, Bill. I'm currently trying to reverse the process, with some small amount of success.

[andrew scott]

Hi Jay, Craig, Bill
I have finish building tau zero, so here is the pic of tau zero :cool:

[Tau Zero]

Hi Jay, Craig, Bill
I have finish building tau zero, so here is the picVery cool indeed, Andrew! ;) :D

My dad drove John Deere tractors, so I'm especially partial to your yellow and green paint job! I'd recommend an orange streamer, though, in case you fly it in fields growing either green or yellow crops! :eek: :rolleyes:

If all goes well, tomorrow's the official C6-5 test flight of my "New, Improved" Tau Zero (with festive SE-14 screw eye!). Hopefully I'll have a positive flight report to post on this thread sometime this weekend.


Cheers, and enjoy,

[CPMcGraw]

Hi Jay, Craig, Bill
I have finish building tau zero, so here is the pic of tau zero :cool:

Hi, Andrew!

Nice finish on the TZ. I might have to do my next one in Kubota orange, just to take this idea one step farther. Someone else will have to do a New Holland blue...

Have you flown yours yet? Hopefully I'll get the chance today to check out the "extended length" version...

[CPMcGraw]

(This is a separate report from the other models flown this afternoon.)

The extended-length Tau Zero has flown, and it was arrow-straight on the A8-3. Recovery was a 1" x 10" streamer, and was nearly without incident. A minor tangling of the shock chord, and a jamming of the recovery wadding (followed by the motor kicking out) were the only problems encountered. The nose cone touched down before the body, which was horizontal and spinning like a football.

Altitude seemed to be less than what RockSim predicted, but without a reliable means of measuring the flight, I am probably underestimating the flight performance. I was nearly straight beneath it during the whole powered portion, and most of the coast phase, so I was looking at an acute angle.

The streamer deployment seemed to be quite gentle, but as mentioned the wadding jammed right at the tube edge, and caused the motor to eject from the rear. I thought I had enough tape around the motor, but it needed a little more thickness. One suggestion for the final release version, which I might implement on my second prototype, is the addition of a motor hook and a thin hold-down sleeve. This could even be just a strip of #20 paper, with the overlap area on top of the hook. Given that the hook would be completely hidden by the ringfin, this would be cheap insurance to keep the motor in-place.

The launch lug position, right under the ringfin and attached to the top-and-side of one of the short subfins, turns out to be an ideal location. I had no problem with binding on the rod.

If I can gather up some local assistance for the next flight session, I might try the "B" motor. The field is large enough, I think, but only with a second or third pair of eyes to track it; not to mention a second pair of legs to chase it down.

I almost flew it again today before leaving the field, but decided against it as it was getting late and I was getting tired. I also didn't want to risk the model at this point with another motor ejection that might not deploy the streamer. Now I have a fully-intact model that will fly again at the next session.

Great job, Jay! An interesting design, a simple build, and a great-flying model. It should make an equally great SEMROC kit when we get all of the first-flight wrinkles ironed out.

[Tau Zero]

Saturday, August 19th -- Flight log for the "New, Improved" Tau Zero with bigger, beefier screw eye.

Flight number 5 on a C6-5: I held my breath, and the Tau Zero tore into the sky. It kicked the motor and free-fell from an altitude of about 1100 feet. There was only a slight ding to the nose cone shoulder.

Flight 6, another C6-5: Stability issues resolved, I used a bunch more masking tape on the motor. Another picture-perfect liftoff and ejection! The partially ejected motor dragged the TZ down tail-first, and busted an outer fin off on impact. (Too much "descending" drag from the streamer?) I used some medium CA for repairs, and prepped the rocket for another flight.

Flight 7, last one of the day (on one more C6-5): I borrowed a 12" plastic parachute from some friends (Thanks, Jim and Aaron Tarter!) to see if I could slow the descent rate a little bit. About 150 feet up, the rocket veered to one side. I didn't think the slightly increased weight of the parachute would make that much stability difference. On recovery, a closer examination revealed that I didn't get the broken fin back on exactly straight, so apparently *that* was the problem.

Time to retire Tau Zero Prototype I, and build a replacement, I guess!


My other two flights were my replacement Estes Wolverine 1.36X upscale (with borrowed WASP nose cone) and my BT-50-based Centuri Groove Tube 1.07X upscale, both on B6-4's. The slightly enlarged Wolverine only made it to about 250 to 300 feet, but recovered nicely. The Groove Tube suffered nose cone separation at an apogee of about 600 feet. My buddy Jim Tarter asked if I had intended "dual recovery" on that flight. I said, "Of *course,*" nonchalantly.


Summary: You can make the Tau Zero stable with a good-sized (Semroc SE-14) screw eye. But you may want to use a parachute with a spill hole for any C motor flights, especially if you've got a hard landing surface. (Which makes me wonder if the streamer would be adequate for a C flight over a healthy and uncut alfalfa field.)

P.S. I forgot to mention that I use a standard Semroc 1.75" inch wide 36" long crepe paper streamer folded in half and anchored to the shock cord.


Cheers,

[Tau Zero]

One suggestion for the final release version, which I might implement on my second prototype, is the addition of a motor hook and a thin hold-down sleeve. This could even be just a strip of #20 paper, with the overlap area on top of the hook. Given that the hook would be completely hidden by the ringfin, this would be cheap insurance to keep the motor in-place.I tried that option with my Scram-Jet clone, and ended up with a nice long gouge in the body tube. :mad: Since then, I *only* use motor hooks in non-minimum diameter designs, where centering rings can secure the hook *much* more effectively than just a sleeve..


I almost flew it again today before leaving the field, but decided against it as it was getting late and I was getting tired. I also didn't want to risk the model at this point with another motor ejection that might not deploy the streamer. Now I have a fully-intact model that will fly again at the next session.Congratulations on resisting "launch fever." Your caution paid off.


Great job, Jay! An interesting design, a simple build, and a great-flying model. It should make an equally great SEMROC kit when we get all of the first-flight wrinkles ironed out.Thanks! :D ;)

It's only taken me seven flights so far. :o :rolleyes:


Cheers,

[andrew scott]

Hi Jay, Craig, Bill


Have you flown yours yet? (TAU ZERO)


Yes Tau Zero has flown, on Sunday.
flew it 2 times, it was arrow-straight on the A8-5 B6-4.
Look like it got to 500 feet on the A8-5 and 800to 900 on the B6-4.
There a ding to the nose cone, hit by the body tube, look like the shock chord is not long enough see the pic . :eek:
Going to use a shock chord 24in instead of 18in chord.

As for Prometheus, *rip* off the pad, and how !!!!!!! on A8-5, 600-700 feet and on a B6-6, 900 to 1000 feet no problem. :cool:

Jay! interesting designs and simple to build, great-flying models
Should make great SEMROC kits (BIG, BIG, BIG hint). :):D:)

[CPMcGraw]

...Tau Zero has flown, on Sunday.
flew it 2 times, it was arrow-straight on the A8-5 B6-4.
Look like it got to 500 feet on the A8-5 and 800to 900 on the B6-4.
There a ding to the nose cone, hit by the body tube, look like the shock chord is not long enough see the pic . :eek:
Going to use a shock chord 24in instead of 18in chord.

Sounds like you had a full day of flying, Andrew. And it sounds like you got some good performances out of those models.

We've been having quite a few 'dis' - 'cuss' - 'shuns' over here for some time concerning those 'hot' dynamite-like deployment charges. My Tradewind prototype took a solid hit, with a large sideways dent near the edge. I'm considering lengthening some of mine to 30" on the elastic; the Kevlar thread is already 24" (which resolves to about 20" ahead of the motor mount...).

As for Prometheus, *rip* off the pad, and how !!!!!!! on A8-5, 600-700 feet and on a B6-6, 900 to 1000 feet no problem. :cool:

Jay! interesting designs and simple to build, great-flying models
Should make great SEMROC kits (BIG, BIG, BIG hint). :):D:)

Jay's got two winners here, no argument. I think both of these designs would make great SEMROC kits, myself.

[CPMcGraw]

Nice photos, too! That nose cone shot, though, just sends chills down my back. It's almost a carbon-copy of the impression left in my Tradewind NC...

I really like that Prometheus color and trim scheme. Just wait until Jay gets the "official" Prometheus decal ready for us. The general idea is that of a Classic Greek hand gripping a lit torch, while the holder is running. The flames sweep rearward...

...At least, that's what it's supposed to look like...:rolleyes:

[Tau Zero]

There a ding to the nose cone, hit by the body tube, look like the shock chord is not long enough see the pic . :eek:Ouch! :mad: Sorry, Andrew! :o


Going to use a shock chord 24in instead of 18in chord.I just checked the elastic cord length on my TZ Prototype I, and it measures 30 inches. So tie a bunch more on to what you've already got!

[EDIT] BTW, did you use a Kevlar thread tied around the thrust ring, and tie the elastic cord to that? If so, how long was your Kevlar?


Jay! interesting designs and simple to build, great-flying models
Should make great SEMROC kits (BIG, BIG, BIG hint).(pretending to be exhausted) Yeah, says you and everybody else. :eek: :rolleyes: ;) :D

Carl and I are trying to figure out the easiest but sturdiest way to incorporate an engine hook right now, so that's the immediate hurdle. We may have a workable solution in sight, though!


Thanks for flying my Tau Zero and Prometheus "Down Under!" :cool:


Cheers,

[Tau Zero]

Saturday, 21 Oct 2006


I took my new (to me) pickup truck out to "Old Home Place Field" (my mom and dad's old farm, which is now a giant hayfield) about 4 p.m. yesterday. Oddly enough, the only rocket I had ready to fly was my "Tau Zero" Prototype II.

I loaded it up with a C6-5, since that's the "problem" motor for this design. I had an "arrow-straight" flight, and it weathercocked into the slight breeze (about 3 mph on the ground). Up and over the top, with ejection just past apogee. :D I tried to take a picture while the Tau Zero was coming down, and managed to "lose" the rocket. It landed about 100 feet away from the pad, just behind a small rise in the field.

The body tube and tail assembly appeared to be undamaged, but the 18" streamer apparently didn't slow the nose cone enough. :( The tip of the nose cone broke off, which indicates that it struck the ground at a pretty good speed (I heard a sound on impact).

Satisfied with the "new, improved" Tau Zero's performance on a C6-5, I throttled the next flight back to a B6-4. Instead of trying to take a picture, I decided to pay attention to the TZ's flight profile. Good thing I did, because this motor decided it was a B6-2, and blew the rocket into 3 separate pieces while it was still "upward bound." :mad: Part of the streamer was floating away, so I didn't bother to track it. The tube and tail assembly still had part of the streamer and were coming down somewhat slowly. I picked out the nose cone and followed it down. As I headed out to recover the nose cone, I suddenly noticed I'd "lost" the rest of the rocket. :o

I ended up hiking a mile and more around that hayfield, scanning it as I went. Oddly enough, the field (and even the dirt) seemed to be predominantly gray. So even though the TZ had orange fins, I *still* couldn't pick it out of the background. :mad:

(heavy sigh) Next time, I get me a professional tracker... even if I have to train them myself.

And now I guess I get to file a MESS report. @%*$ Estes thermonuclear ejection charge! :mad: (And I can finally commiserate with Bill Eichelberger.)


Cheers,

[CPMcGraw]

...I loaded it up with a C6-5, since that's the "problem" motor for this design. I had an "arrow-straight" flight, and it weathercocked into the slight breeze (about 3 mph on the ground). Up and over the top, with ejection just past apogee. :D I tried to take a picture while the Tau Zero was coming down, and managed to "lose" the rocket. It landed about 100 feet away from the pad, just behind a small rise in the field.

The body tube and tail assembly appeared to be undamaged, but the 18" streamer apparently didn't slow the nose cone enough. :( The tip of the nose cone broke off, which indicates that it struck the ground at a pretty good speed (I heard a sound on impact).

I used a 2" x 20" and had excellent results, but it was still faster than, say, a 12" parachute. When such a small model gets over 1000', a parachute is tantamount to a guaranteed hike (or drift-away).

Satisfied with the "new, improved" Tau Zero's performance on a C6-5, I throttled the next flight back to a B6-4...and blew the rocket into 3 separate pieces while it was still "upward bound." :mad: ...

And now I guess I get to file a MESS report. @%*$ Estes thermonuclear ejection charge! :mad: (And I can finally commiserate with Bill Eichelberger.)

Big painful ouch! :( Sorry to hear of the loss, Jay. No fun to lose a model under any circumstances, but a simple fly-away is less painful since you feel like it gave it's all for that one flight. Having a T-Nuke destroy it on the way up is just poor quality control over those motors. Maybe we should start a thread on bad motor batches here on the forum, something we can all quickly compare against. What batch code was on that B6-4?

[A Fish Named Wallyum]

Saturday, 21 Oct 2006


I took my new (to me) pickup truck out to "Old Home Place Field" (my mom and dad's old farm, which is now a giant hayfield) about 4 p.m. yesterday. Oddly enough, the only rocket I had ready to fly was my "Tau Zero" Prototype II.

I loaded it up with a C6-5, since that's the "problem" motor for this design. I had an "arrow-straight" flight, and it weathercocked into the slight breeze (about 3 mph on the ground). Up and over the top, with ejection just past apogee. :D I tried to take a picture while the Tau Zero was coming down, and managed to "lose" the rocket. It landed about 100 feet away from the pad, just behind a small rise in the field.

The body tube and tail assembly appeared to be undamaged, but the 18" streamer apparently didn't slow the nose cone enough. :( The tip of the nose cone broke off, which indicates that it struck the ground at a pretty good speed (I heard a sound on impact).

Satisfied with the "new, improved" Tau Zero's performance on a C6-5, I throttled the next flight back to a B6-4. Instead of trying to take a picture, I decided to pay attention to the TZ's flight profile. Good thing I did, because this motor decided it was a B6-2, and blew the rocket into 3 separate pieces while it was still "upward bound." :mad: Part of the streamer was floating away, so I didn't bother to track it. The tube and tail assembly still had part of the streamer and were coming down somewhat slowly. I picked out the nose cone and followed it down. As I headed out to recover the nose cone, I suddenly noticed I'd "lost" the rest of the rocket. :o

I ended up hiking a mile and more around that hayfield, scanning it as I went. Oddly enough, the field (and even the dirt) seemed to be predominantly gray. So even though the TZ had orange fins, I *still* couldn't pick it out of the background. :mad:

(heavy sigh) Next time, I get me a professional tracker... even if I have to train them myself.

And now I guess I get to file a MESS report. @%*$ Estes thermonuclear ejection charge! :mad: (And I can finally commiserate with Bill Eichelberger.)


Cheers,

A-HEM! I don't want to say "I told you so", so I'll just say "Told ya". I feel like Chicken Little. No one believed me until some guy got whacked in the head with a falling urinal.
I was all set to fly today, but the winds whipped up and it was cancelled before I woke up. Major bummer, especially since the MadCow Hawk was all set to fly leadoff. I've never flown a G38 before. :eek: .

[Tau Zero]

Satisfied with the "new, improved" Tau Zero's performance on a C6-5For those who are interested: Jay's "Tau Zero" EMRR flight logs (http://www.rocketreviews.com/cgi-bin/flightlog/flightsearch.cgi?detail&&Semroc%20Tau%20Zero&&-&&-&&-&&-&&&&-&&-)


Cheers,

[Tau Zero]

A-HEM! I don't want to say "I told you so", so I'll just say "Told ya". I feel like Chicken Little. No one believed meI didn't *not* believe you. Come to think of it, some 1/4 and 1/2A motors blew my Satellite 62SL clone to bits down at NSL 2002 outside of Phoenix. :eek: :mad:

This is just the first time in a *long* time (since I've done a lot more designing instead of actual flying... at least until this summer, I guess). :o


until some guy got whacked in the head with a falling urinal.As my youngest daughter (age 8.5) would say,

"*Ew.*" :eek:


Cheers,

[CPMcGraw]

Jay,

I started a flight log on EMRR for the 10" TZ, so maybe folks will read both logs and start drooling for this previously-unknown SEMROC kit that no one else has seen... :rolleyes: :D OK, well, maybe four of us have seen it, one down in NZ...:cool:

Here's the link: TZ10 Logs (http://www.rocketreviews.com/cgi-bin/flightlog/flightsearch.cgi?whatsnew&&Semroc%Tau%Zero&&-&&-&&-&&-&&TZ 10&&-&&-)

Bill E., how about tossing a log for your prototype TZ onto EMRR? Call it the fourth prototype. Jay's already talked about two, mine makes three...

Just noticed on the original log, my three entries now show up along with Jay's first five, and in chronological order. Neat...:cool:

[Tau Zero]

I started a flight log on EMRR for the 10" TZGood job! BTW, you'll have to spell out the word 'inch' since double quotes " get lost in translation. :eek: :mad:


so maybe folks will read both logs and start drooling for this previously-unknown SEMROC kit that no one else has seen... :rolleyes: :D OK, well, maybe four of us have seen it, one down in NZ...Close, but no cigar. You're thinking of extreme southeastern OZ-tralia, perhaps? :rolleyes:


Bill E., how about tossing a log for your prototype TZ onto EMRR? Call it the fourth prototype.Here's Bill's original log, listed under "Potatohead Rocketry" ('cause Bill's "Fishhead," don'tcha see):
http://www.rocketreviews.com/cgi-bin/flightlog/flightsearch.cgi?detail&&Potatohead%Rocketry%-%Tau%Zero


Just noticed on the original log, my three entries now show up along with Jay's first five, and in chronological order. Neat...:cool:Actually, I had 4 up, and added 5 more last night, so between you and me, we're up to 12 flights on this design. Bill's got 3 flights, and if I recall correctly, Andrew Scott (he of the John Deere green and yellow Tau Zero) has 2.


BTW, I'm thinking my Tau Zero Prototype III will have a 1.75" x 24" streamer folded in half. :D The 36" streamer on Prototype I was *way* too long. :mad:

Cheers,

[CPMcGraw]

Good job! BTW, you'll have to spell out the word 'inch' since double quotes " get lost in translation.

Yea, found that out after hitting the submit button...:o


Close, but no cigar. You're thinking of extreme southeastern OZ-tralia, perhaps?

Geography was never my strongest science. Still ain't...


Here's Bill's original log, listed under "Potatohead Rocketry" ('cause Bill's "Fishhead," don'tcha see):
http://www.rocketreviews.com/cgi-bin/flightlog/flightsearch.cgi?detail&&Potatohead%Rocketry%-%Tau%Zero

I didn't see his, but I'll go read them. I need to start logs on my BARCLONEs, too...

Addendum: Logs for the most-recent BARCLONE flights are now up on EMRR. I also found Bill's logs. TZ10 will be flying again at the next opportunity, so maybe I can get some additional entries for you.

[Tau Zero]

I'm thinking my Tau Zero Prototype III will have a 1.75" x 24" streamer folded in half. :D The 36" streamer on Prototype I was *way* too long. :mad: [SNIP]

The C6-5 flight last Saturday (21 Oct) proved that an 18" (non-folded) streamer didn't have *enough* drag to protect the nose cone, but the tail section appeared to be undamaged. :D Hence the intermediate length for *this* go-around.Decent flying weather will soon no longer be available here in Southern Idaho (and around much of the US), so yesterday I realized I needed to get some "emergency" test flights in on my "new, improved" Tau Zero before it's too late.

I had the two body tube and fin assemblies from my first *very rough* attempt at building Tau Zero Prototype II. The inner fins weren't lined up perfectly straight, but I shot both sections with "Emergency Orange" so I could *see* the rest of the rocket if it separated from the nose cone again.

I sprayed the broken tip of the nose cone used on both Prototypes I and II with light gray, just so any "landing" damage would be evident. This afternoon, I used medium CA to glue together the fin/tube assemblies, and let it dry for 30 minutes while I drove to "Old Home Place Field" (slightly less famous than, say, "B6-4 Field"). :eek: ;) (Picture #1)

I loaded Tau Zero Prototype II-B with an A8-3 and pushed the launch button. After seeing this model on a "C" motor, the 300 foot flight was anti-climatic, except the 24" streamer made the TZ fall "tail-first" for a while, but it landed parallel to the ground. There was no visible damage, and the rocket landed about 100 feet from the launch pad. It looks like I'll have to extend the elastic shock cord from 24" to 30" to see if I can avoid the snapback pictured in Photo #2.

The sun was going down for flight #2 on a B4-4 (since that was the only B*-4 motor the variety store had today). About 500 feet up, the rocket arced away... AND SEEMED TO DISAPPEAR INTO THE CLEAR BLUE SKY. :eek: (Middle age is officially here, and these transitional lenses are no help!) I managed to find the rocket about 300 feet from the pad, with some damage to the unfilled and unfinished fins (Photo #3).

I shoved a C6-5 for a final flight. I lost sight of the rocket (again) on its way up, but the sky was dark enough that I saw the flare of the ejection charge. I lost it again, but thanks to the EMERGENCY ORANGE, :D I managed to recover the model 100 feet upwind of the pad (after reorienting the launch rod), even with the fading light.

Overall, these "just in time" flights have confirmed my suspicions (good and bad) about this design, so it looks like I can finalize the parts list. :cool:


Cheers,

[CPMcGraw]

The sun was going down for flight #2 on a B4-4 (since that was the only B*-4 motor the variety store had today). About 500 feet up, the rocket arced away... AND SEEMED TO DISAPPEAR INTO THE CLEAR BLUE SKY. :eek: (Middle age is officially here, and these transitional lenses are no help!) I managed to find the rocket about 300 feet from the pad, with some damage to the unfilled and unfinished fins (Photo #3).


Unless you know what the model hit on the ground, that fin tip looks like the shock chord was pulled through the fin. I'm trying to picture the deployment in my mind and figure out how the elastic, Kevlar, or the streamer leader got pulled sideways through the balsa. You don't have any tube edge to strike up there, so that's ruled out.

I'm wondering if maybe you should eliminate the elastic completely, and substitute a 48" length of Kevlar thread? Might be worth a test flight, the only thing that you might loose would be a bone-pile throw-down.