OpenRocket contest help

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GoroAkechi7

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For a local contest I´m required to build a rocket under the following regulations:

(English is not my first language so I apolagize in advance for any grammar errors)

-Rocket must have a mass of at least 200 grams
-Can only use one engine and it hast to be the D11 from Estes
-Estability must be between 1,5 and 2,5
-Must have an empty cilindrical compartment of at least 20 cm, with a 5 cm external diameter and 4,8 internal diameter. THe minimal measure of the rocket is 27 cm (the measure of the engine + the empty compartment)
-The fins cannot go pass the engine (back of the rocket), in fact nothing can be located behid the engine
-Nothing can be in front of the nose of the rocket

As of right now I have managed to make a rocket with exactly 200g, that can reach an apogee of 252 meters with a estability of 2,4. My professor has told me this results are positive but I believe there is a lot of room for improvement. It also doesnt like too impressive to be honest, it's actually rather simple.

Any help that you can provide is extremely appreciated, even the smallest tip will do.
(The file attached is the current model of the rocket)
 

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brehos110

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Hello! Could you please tell me what the objective of the contest is, like do you want the rocket to travel to a certain height or are the building objectives all that the competition requires?
 

GoroAkechi7

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Hello! Could you please tell me what the objective of the contest is, like do you want the rocket to travel to a certain height or are the building objectives all that the competition requires?
It's supossoed to reach the highest possible apogee while following all regulations
 

K'Tesh

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Make your payload section match its minimum dimensions, then create a transition that tapers down to the diameter of the motor tube. Try elipsoid fins.
 

brehos110

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Make your payload section match its minimum dimensions, then create a transition that tapers down to the diameter of the motor tube. Try elipsoid fins.
I agree with this. The main first part that you need to do is get a simulation that is 95 to 100% accurate so that you can rather accurately know how high your rocket will fly you need to move the parachute farther down the rocket so your simulation is more accurate.
Now I see that you have 2.43 calibers of stability in a contest you do not want this much stability to fly the highest I would recommend trying to hit about 1.5 to 1.7 calibers of stability.
In order to get closer to this value of stability the first thing I would usually recommend is shortening the rocket but you have your height at a good value. I would recommend switching to elliptical fins and making them as small as possible.
Now, starting from top to bottom of the rocket:
the rocket’s nose cone should optimally be parabolic, power, or haak series nose cone.
the body tube is pretty good currently
the fins are better being elliptical and you only want three fins if you have four
with the launch lug my question is do you have or need a launch lug if you need one put between the joint of the fin and the body tube.
alright also you definitely want to use the transition from the body tube to the payload as it will help with aerodynamics
for the paint you want to paint the rocket all one color start by paint the rocket with primer sand the primer and do this process 2 to 3 times then paint the rocket one color this will not give the best finish but it is better than just painting the rocket.
That is pretty much it if you have any more questions please feel free to ask them.
 

bill_s

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Tried this and difficult to get a "lot" of improvement. With tailcone got 279m. Make sure fins are thin (0 or stupid thin Airfoil) and surface is set to polished. Tends to be an ugly rocket!
 

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