# Whos willing to tackle this project?

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#### Const Star

##### Well-Known Member
Ive always wanted to build a REALLY TALL rocket, and what better than to get inspiration from the tall SOB himself God-Zilla.
(i dont mind people building rockets based on my ideas, and any constructive criticism is welcome)

Body Tube: 4.0 inches in diameter
: 60.0 inches in height

Nose Cone: 4.0 inches in diameter
: 12.0 inches in height
: Very sharp pointed tip

Fins: 2 sets of 4, 8 inch fins acute triangle shaped

2 Stages: 1st stage (29mm - F20-W4)Econojet
: 2nd stage (29mm - F10-8)Apogee

Recovery: Dual 18 "parachutes that Deploy after each stage

Id Finish this baby off with a killer Fade Flame paint job. after a white base coat

Can anyone tackle this project? might be too much for me to tackle any time soon

#### BlueNinja

##### Well-Known Member
Well, again I have to say you would need bigger motors. F's won't cut it for a design like this, especially if you use a conical 4" nose.

WHy?

F20-4 is an awesome motor, however I am guessing this rocket would come in at 3-4 lbs. IIRC, divide the avg thrust by 5 to get a rough safe liftoff ratio. 20/5=4. You would technically have enough thrust, but it would be marginal. An F40 would be more likely.

Now about the top stage, is that also 4"? If you used a transition and downscaled it to 2" or so, and F10 would RIP in it. Another note about staging: F20s and F10s are composite motors, harder to light than Questes. You need an electronic timer to light them, can't just blow the top of the propellant off.

I know you said you probably wouldn't build this, but a few notes for if you ever do.

#### Const Star

##### Well-Known Member
diameter would stay the same i spose, but i guess ur right about the motors being composite, i hadnt thought about the programed ignition or anything....

hmm, but i guess its still possible just not by me. i lack the know how.

and i figured the motors would be sufficient being the f20-4w has a rather quick burn time at a lil under 3 seconds, and the 2nd stage has 7.8 second burn time, nice for the boost into extreme height, especially after it drops the weight from the first stage.

id still like to see someone tackle this project, seems like a killer rocket in my eyes. if a few changes need to be made thatd be fine.

infact, anyone can post exactly how they would build it if they dont wanna actually build it. i know itd be costly, and the body tube would need a bit of strength to withstand the height flex and bursts from both motors.
i suppose the recovery chutes would need to be considered as well.

#### Micromeister

##### Micro Craftman/ClusterNut
TRF Supporter
If you'd like to build a really tall "decent" diameter sized Demo rocket that will get good altutude and still weigh in a one pound, tury building a 2 staged BT-70/Bt-60 "Grumpy Dog" with a D12-0/D12-5 and 2 18" hemi nylon chutes this 119.75" model tips the scales at 452.9gram liftoff weight. fun flyer aslo

If I were to do your 6 footer i'd go with BT-101 and make it a 5- D12 cluster

#### lalligood

##### Well-Known Member
And if the RR isn't tall enough for you, try the ASP Tall Boy

It only has a single 24mm MMT instead of a 3-motor cluster...

HTH,

#### bobkrech

##### Well-Known Member
Const Star

It sounds like your new to rocketry. You might want to check out http://esteseducator.com/ and http://www.apogeerockets.com/education/index.asp to get some background on designing rockets.

You can also download wRASP (it's free) and run a simulation on the rocket you want to build. http://www.wrasp.com/

With wRASP, start with a Binder Design Excell and add a booster, since in wRASP you only have to specify the BT diameter, stage weight, and the motor. It will be a pretty good approximation of the rocket you want to build.

You will find that a 2-stage 4" rocket will most likely weigh in over 1 pound, making it a large model rocket and will require filing and LMR with the FAA. Not a problem but it means you can't just go out and fly it on a whim.

You will need electronics to ignite the second stage motor, since you are using a composite motor for the second stage.

While it is possible to use an F20-4 for the first stage, you are going to need a 6 foot launch rod, and even with that, the rocket will be unstable in anything other than a dead calm. A rocket this large really needs more initial thrust, especially on a windy day, and that's why an F40-4 was suggested.

If the upper stage is an F10, it has to be the shortest delay you get. Apogee is achieved about 3 seconds after second stage burnout, and the shortest F10 is a -4. You will strip the chute if you used a longer delay.

I think that the alternative suggestions in the thread on larger rocket kits might be a better learning avenue (and less expensive) than going right out and attempting to build this rocket. Your trying to do too much, too soon, and you're likely to get frustrated

Bob Krech

#### Const Star

##### Well-Known Member
i appreciate all the comments and suggestions. like i said though ill probably never get to build this, or atleast anytime soon. since yes i do lack the know how. lol, not ashamed to admit it.......much....

i was actually discussing the design with someone a few minutes ago, talking about using bigger motors, or a cluster pattern.

my original design was to make the diameter only 2 inches but i thought itd cause alot of flew once the motors ignited.... i gues it depends alot on the material. and im not familiar with electronic on board stuff, so itll be a while before i tackle the really big stuff anyways

if anyone out there wants to make a version of this rocket please do. id feel honored to see it done properly. i still plan to do Rock-Zilla some time in the future

#### r1dermon

##### Well-Known Member
comeon man!!! dont give up so easy. timers are no more than 60 bucks... you can stage from a G-something, G80 or something, to an F20, F50's also have good spank. definately check out the links that bob krech posted, those are awesome resources, thats where i learned most of the stuff i know. a 4" diameter 2 stager aint gonna be light, thats why you're going to want to use a G or better for the first stage. at 4lb's a G80 would lift it off for a realistic flight. go do some research on timers and payload/electronics bays. its not as complicated as it seems.

#### DynaSoar

##### Well-Known Member
Originally posted by Const Star
Ive always wanted to build a REALLY TALL rocket, and what better than to get inspiration from the tall SOB himself God-Zilla.
(i dont mind people building rockets based on my ideas, and any constructive criticism is welcome)
Rinji news o moshiagemasu!
Godzilla ga ginza hoomen e mukatte imasu!
Daishkyu hinan shite kudasai!

"With a purposeful grimace and a terrible sound
He pulls the spitting high tension wires down."

Here's the start of my next DESCON entry.
Guess who epoxied to a coupler, which is the nose cone for a BT80 based body (legs and tail for 3 fins).

"Oh no, they say hes got to go,
Go go godzilla.
Oh no, there goes Tokyo,
Go go godzilla."

No, I don't know Japanese. That's in the lyrics.

#### Stymye

##### Well-Known Member
remember the turtle? he would make a fine saucer!

#### Const Star

##### Well-Known Member
nice nose cone there lol

#### BlueNinja

##### Well-Known Member
r1dermon- you can actually get a timer for less than $30 from Prefectflite, or is that model the discontinued one? If so, you're looking at$35.