Missle Project

[Bigander]

Well here is my missle project. I made nearly everything from scratch. The transition my father turned out for me on a lathe. The lower fins are balsa and the uper fins are thin phenolic that i had lying around. I used Killz Camo system. 24mm mm. Probably an E-9 on first attempt. I've been looking at getting an at initiator rms starter pack and get into mpr's. So in the future it might be an at bird for me.

 

[Micromeister]

Ah did you forget something??? Like a link or pic or something

 

[Maagic]

You kids today... always asking for pics or video. Back in MY day we just used our imagination. Drew on a piece of bark or in the dirt with a stick.

And we LIKED it.

 

[Bigander]

I'm working on the pic srry I'm trying to take down the size w/ irfanview

 

[Bigander]

Testing 1...2...3

 

[Bigander]

Too low of a quality

 

[Bigander]

I might look to buying rms stuff for this rocket instead of buying the initiator starter set. I would love to get into at but i just have to constantly make sure i don't spend too much. Would someone mind making me alist of stuff to buy and give me a few hints. I want to see bout using an E-18. I don't need a pad since i'm using my rail. Will my Estes engine hook be able to hold up?? Ne help is appreciated!

 

[jadebox]

Originally posted by Bigander
Well here is my missle project. I made nearly everything from scratch. The transition my father turned out for me on a lathe. The lower fins are balsa and the uper fins are thin phenolic that i had lying around. I used Killz Camo system. 24mm mm. Probably an E-9 on first attempt. I've been looking at getting an at initiator rms starter pack and get into mpr's. So in the future it might be an at bird for me.

It looks too big for an E9 and with the upper fins any wind at all will cause a problem. Depending on how heavy it is, an E15 or larger motor may be a better choice.

-- Roger

 

[Bigander]

Would an E11-3J work?? I really want to get started in aerotech and i am trying to read up but would like some input from the community here cause u guys amek things sound more simple!

 

[heada]

If we look at the certification doc for the Estes E9 motor:

https://wwwtest.nar.org/SandT/pdf/Estes/E9.pdf

We see that it has an average thrust of 9.02 N and a peak thrust of 19.47 N This means (when looking at the thrust graph) that it pushes at the very beginning with 19.47 N (4.3 lbs) and then tapers off to 9.02 N (2 lbs)

The E11 from Aerotech:

https://wwwtest.nar.org/SandT/pdf/Aerotech/E11.pdf

Has a peak thrust at 21.64 (4.5 lbs) and an average thrust of 12.01 N (2.5 lbs)

The E15 from Aerotech:

https://wwwtest.nar.org/SandT/pdf/Aerotech/E15.pdf

Has a much high peak thrust of 28.84 N (6.5 lbs) and an average thrust of 15.06 N (3.3 lbs)

Since you want to use the RMS case, I would suggest the E28 from Aerotech:

https://wwwtest.nar.org/SandT/pdf/Aerotech/E28.pdf

It has more kick off the pad (peak thrust of 50 N (11 lbs)) and a high average thrust (30.5 N (6.8 lbs)) so that your rocket with the fins near the tip (forward canards) will not be effected by wind as much. If you would like to stay with Aerotech but go with single use motors, the E30 is a good one as well.

https://wwwtest.nar.org/SandT/pdf/Aerotech/E30.pdf

Keep in mind the normal 5:1 thrust to weight ratio is a good thing to shoot for too. Going higher is ok, going lower can be problematic if you're not careful.

-Aaron

 

[Bigander]

Wat bout an f12-3J?? I want something in the Black Jack so i get that nice black smoke from my rocket.

 

[heada]

Traditional black jack motors have a lower average thrust so in order to get a more stable rocket, you'd have to use a larger motor. The F12J (23.5N peak/14.7N avg) is very similar to the E11 (21.6N peak/12N avg) I think you wouldn't get a motor you could use with a rocket like that until you get to something near the G33 (requires a LEUP due to propellant weight)

I think what you would want for the dense black smoke and still be stable is the newer FastJack motors. I don't know of any SU or RMS FJ motors in 24mm. The F23FJ would be nice, but it is 29mm.

Would you be willing to go with a louder motor with dense white smoke? The White Lightning motors are more powerful than Black Jack motors as well as louder. They produce denser smoke, but its white and not black. The E18 (30N peak/17N avg) or maybe the F24 (40N peak/22N avg) would be ok I think (not knowing the weight of your rocket)

-Aaron

 

[Bigander]

That will work. Not sure about the weight though. If someone can rocksim it for me that would be great. Bottom section is bt-80 bout 2feet. The top is Bt-60 bout 1foot. The transitions is solid balsa bout 2-3 inches long. The fins are about 6x5 through the body. the uppers are 2inch squares sliced in half to make triangles. in the center bout 1 1/2 foot 24mm motor mount w/ birchply centering rings at both ends. 36 inch top flight x type parachute. The transition up makes the nose cone. I'm using 5" of tubular nylon for the Strapping.

 

[jadebox]

Originally posted by Bigander
That will work. Not sure about the weight though. If someone can rocksim it for me that would be great. Bottom section is bt-80 bout 2feet. The top is Bt-60 bout 1foot. The transitions is solid balsa bout 2-3 inches long. The fins are about 6x5 through the body. the uppers are 2inch squares sliced in half to make triangles. in the center bout 1 1/2 foot 24mm motor mount w/ birchply centering rings at both ends. 36 inch top flight x type parachute. The transition up makes the nose cone. I'm using 5" of tubular nylon for the Strapping.

You download a 30-day trial of RockSim:

https://www.apogeerockets.com/rocksim_demo.asp

It is a good idea to model your rocket in RockSim just to make sure it's stable and that your motor selections are appropriate. It's also a lot of fun!

RockSim will tell you if you need to add nose weight for stability. Normally, for any rocket with fins up front it's a necessity because the front fins move the center of pressure of the rocket forward. But it sounds like you made the top of your rocket heavy with the balsa and nylon 'chute and all that adding nose weight may not be required.

Using RockSim, however, you can help ensure that the rocket will be stable. If you enter the parts correctly into RockSim, it'll determine the weights with pretty-good accuracy. Then, load a motor in the simulation and RockSim will tell you if the rocket is stable. You can then "launch" the rocket and watch a 2-D plot of the flight and see if the parachute deploys at the right time.

Another way to check the rocket's stability is to load it with the motor you plan to use then perform a "swing test." Tie a string around the body tube at the point where the rocket balances (the center of gravity). Then swing it around and see if it always points the way it is swinging. If so, you can be pretty sure it'll fly right.

The reason I'm encouraging you to use either RockSim or a swing test (even though I'd bet your rocket would fly okay anyway) is that you've obviously put a lot of work in it. I wouldn't want to see that investment lost if the rocket isn't stable.

-- Roger

 

[heada]

I hobbled it together in RocSim and it came out to 14.5 oz with CP at 32.6 inches and CG at 24.2 inches empty with a margin of 5.2 empty.

E12 max alt of 477ft and 95mph with a delay of 3.2 seconds
F12 max alt of 664ft and 137mph with a delay of 2.5 seconds
F24 max alt of 878ft and 166mph with a delay of 4.4 seconds
F39 max alt of 989ft and 199mph with a delay of 6.2 seconds

I had to guess on the shape of the fins and they look wrong in the sim. Since that will change the CG and CP, you might want to measure them and get it more accurate than my guess.

-Aaron

 

[Bigander]

Thanks, Can u put the pic in a jpg file. I don't own rocksim cause of the price. I just needed a rough weight estimate cause i really don't have nething to measure that w/. So i take it i will need FAA notification to fly this.

 

[Bigander]

I kinda used up my trial already. I guess i can do it quick on my other computer.

 

[heada]

Here is the jpg export from RocSim. The rocket is fine without motor, but when you add even the E12, its just a tad over 16 oz and would require an FAA NOTAM (not a waiver) At this point, unless it is built VERY light, I'd stick a bigger motor in it (F39 would be great) and enjoy it. Its not going to go so high that you can't visibly track it regardless of motor since it is a 24mm.

-Aaron

 

[Bigander]

I'm sure epoxy would send it over. I did through the tube fins and put epoxy on the mm and put filets on the tube.

 

[Balltip]

Looking good! Just remember one of the most important things when launching a camo rocket.










...a really colorful 'chute or you'll loose it to the weeds!

 

[Bigander]

Oops got a black chute!!
Large enough to track though!

 

[heada]

Black 'chute on white snow is not that hard to track. Black 'chute on dark midwest topsoil is almost as good as invisible. I'd attach a swivel or something similar to the place where you'd attach the parachute and have the ability to swap out parachutes as needed. This will not only let you set your color based on where you're flying but also your size (smaller for the soft topsoil, larger for hard concrete)

I suggest two very dramatic colors if at all possible. PML has the right idea with blue and orange. Very rarely will you see that combination in the wild.

-Aaron

 

[Bigander]

I'm a PA boy so most of my flying is on or over grass.

 

[11bravo]

Originally posted by Bigander
Testing 1...2...3

Oh yeah, that cleared things up totally!