Ye Olde Rocket Forum - Jay's Tau Zero A-C Launch

#11

07-16-2006, 10:45 PM

Tau Zero

Incurable SEMROC Fan

Join Date: Mar 2005

Location: Twin Falls, Idaho, USA

Posts: 2,319

Devilish (?) details

Quote:

Originally Posted by CPMcGraw

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.

Quote:

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.

Quote:

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...

...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!

Quote:

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.*

Quote:

Originally Posted by andrew scott

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

Andrew,

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!

Thanks, and cheers,

__________________
Jay Goemmer
"Centuri Guy"/"Tau Zero"
YORF Member 28
Semroc SAM #0029
NAR 86131

"I think about organizing things all the time. Never seems to happen. I find something that piques my interest and I'm off on a quest. Or a Centuri.

"

--Bill Eichelberger, 02/22/2022

“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

Last edited by CenturiGuy : 10-16-2006 at 10:30 PM.

#12

07-16-2006, 11:37 PM

A Fish Named Wallyum A Fish Named Wallyum is offline

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Location: Ft. Thomas, KY

Posts: 8,617

Quote:

Originally Posted by CenturiGuy

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!

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

__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Centuri Design Contest F-150 Hurricane Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark, Groonie Der V 1/2

#13

07-16-2006, 11:42 PM

Tau Zero

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Join Date: Mar 2005

Location: Twin Falls, Idaho, USA

Posts: 2,319

"Grip it and rip it!"

Quote:

Originally Posted by A Fish Named Wallyum

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.

"

--Bill Eichelberger, 02/22/2022

“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

#14

07-17-2006, 12:06 AM

A Fish Named Wallyum A Fish Named Wallyum is offline

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Quote:

Originally Posted by CenturiGuy

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.

#15

07-17-2006, 12:18 AM

Tau Zero

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Join Date: Mar 2005

Location: Twin Falls, Idaho, USA

Posts: 2,319

(smacks forehead)

Quote:

Originally Posted by A Fish Named Wallyum

Wall E. Coyote - SUPER genius

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

Quote:

I used a streamer with only Kevlar for a shock cord and a decent size screw eye.

One of Carl's? I used an SE-10, but maybe I should bump it up to an SE-12 or even SE-14!

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

Cheers,

"

--Bill Eichelberger, 02/22/2022

“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

#16

07-17-2006, 12:52 AM

A Fish Named Wallyum A Fish Named Wallyum is offline

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Quote:

Originally Posted by CenturiGuy

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

One of Carl's? I used an SE-10, but maybe I should bump it up to an SE-12 or even SE-14!

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

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.

#17

07-17-2006, 01:51 AM

Tau Zero

Incurable SEMROC Fan

Join Date: Mar 2005

Location: Twin Falls, Idaho, USA

Posts: 2,319

Nailing down the nose weight

Quote:

Originally Posted by A Fish Named Wallyum

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.

Quote:

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,

"

--Bill Eichelberger, 02/22/2022

“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

#18

07-17-2006, 11:11 PM

Tau Zero

Incurable SEMROC Fan

Join Date: Mar 2005

Location: Twin Falls, Idaho, USA

Posts: 2,319

Tau Zero -- Screw Eye Woes

Quote:

Originally Posted by CenturiGuy

I used an SE-10, but maybe I should bump it up to an SE-12 or even SE-14!

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,

"

--Bill Eichelberger, 02/22/2022

“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

#19

07-17-2006, 11:35 PM

Carl@Semroc Carl@Semroc is offline

Junior ??? Rocketeer

Join Date: Mar 2005

Location: Knightdale, NC

Posts: 1,470

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.)

__________________
Carl McLawhorn
NAR#4717 L2
semroc.com

#20

07-18-2006, 12:29 AM

Tau Zero

Incurable SEMROC Fan

Join Date: Mar 2005

Location: Twin Falls, Idaho, USA

Posts: 2,319

Eureka!

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!*

Quote:

Originally Posted by CenturiGuy

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!

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!

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!)

+++

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

Quote:

Originally Posted by James Pierson

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.

Quote:

Sounds like you get to play with Rocksim a bit.

Indeed.

Cheers,

"

--Bill Eichelberger, 02/22/2022

“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

Last edited by CenturiGuy : 07-18-2006 at 12:41 AM.

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