# Trajectory Optimization Using Nose Cone Stabilizers

#### Winston

##### Lorenzo von Matterhorn
That's the title of the project which I assume may mean compensation for weathercocking seen in an NRA ad found in the March/April 2021 issue of Sport Rocketry:

Trajectory Optimization Using Nose Cone Stabilizers
by 2019 NRA Junior Member Science Fair winner Lalitha Dhyaram

Anyone know any details?

#### shockie

##### High Plains Rocketeer
That's the title of the project which I assume may mean compensation for weathercocking seen in an NRA ad found in the March/April 2021 issue of Sport Rocketry:

Trajectory Optimization Using Nose Cone Stabilizers
by 2019 NRA Junior Member Science Fair winner Lalitha Dhyaram

Anyone know any details?
I wish the NAR would collect these Sci Fair winners papers so we could look at them.

#### KenECoyote

##### Well-Known Member
TRF Supporter
I googled and found the info. Excerpt:

"Project # J1719 Category: Physics - Aerodynamics/Hydrodynamics - Jr Objectives/Goals: The objective of this project is to determine whether finned nose cone stability extensions can help improve the trajectory of a rocket resulting lower landing distance, and if so, which stabilizer helps the rocket perform the best. Materials/Methods: Nose cone stability extensions were constructed with various fin counts using cardboard and balsa wood. Rockets were constructed using commercial rocket sets to maintain consistency in testing. Launch equipment was assembled at the test site. Landing distance measurements were taken using a measuring tape. Utilized altimeter to record the altitude. Angles to apogee point taken from a inclinometer and horizontal distance from the launch pad were measured, then calculated using trigonometric formulas to find the altitude. Data was evaluated by testing conditions, validity, and analytical relevance. Results: The overall average results of the landing distances of the rockets, excluding outlying and impotent data, are as follows: 2-finned = 12.7423 m, 3-finned (aligned) = 13.8007 m, 5-finned = 15.80515 m, 4-finned = 17.018 m, control (original model) = 17.7038, and 3-finned (dis-aligned) = 23.4696 m. Conclusions/Discussion: The experimental results of this project provide a clear answer to the research question: Among the 5 different nose cone stabilizers tested along with the original, the 2-finned stabilizer had the optimal performance in optimizing rocket trajectory among the rest. These results help provide a solution to rocket trajectory optimization utilizing modification of the rocket body shape, making it pertinent to current rocketry. Summary: This project determined that nose cone stabilizers improve the trajectory of rockets, and the 2- finned stabilizer performed the best among the nose cone stabilizers tested. "

Funny thing is that I've been working on something similar for over a month now. My version has an internal pendulum weight.

#### KenECoyote

##### Well-Known Member
TRF Supporter
Of note is that "NAR" was misspelled "NRA"...that brings up a lot of other results!

#### shockie

##### High Plains Rocketeer
I wonder what would happen if you had a spinning 1/3 of the nose cone/fin unit as the tip of a nose cone. while the rest of the rocket didn't spin.

something like this:

https://www.tinkercad.com/things/7xuOaWLV9cd-12-in-pvc-pipe-paper-rocket-nose-cone-fins. The spinning would be from canted fins on the nose cone it self.....so the amount of spin and any forces produced would be proportional to the air speed of the model rocket itself.

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#### KenECoyote

##### Well-Known Member
TRF Supporter
I wonder what would happen if you had a spinning 1/3 of the nose cone/fin unit as the tip of a nose cone. while the rest of the rocket didn't spin.
One of the members responding on my thread is working on that (see post #20 if you want to skip to the rotating part):
Thales Starstreak build | The Rocketry Forum

Of note is that I had worked on a spinning rear fin can a number of years back and the hard part is "while the rest of the rocket didn't spin". All bearings would have some friction and so a rocket in flight has much less resistance to rotating in the air vs. the resistance in the bearings...especially given the G forces on one of the axes on boost.

#### shockie

##### High Plains Rocketeer
Here's a poor diagram to give you my idea. only the top 1/3 of the nose cone rotates. Using teflon tube and ring attached to rest of nose cone. Finlets on the rotating/spinning nose cone tip. in essence the spinning nose tip finlets might be considered a sort of rocket propeller.

#### KenECoyote

##### Well-Known Member
TRF Supporter
Here's a poor diagram to give you my idea. only the top 1/3 of the nose cone rotates. Using teflon tube and ring attached to rest of nose cone. Finlets on the rotating/spinning nose cone tip. in essence the spinning nose tip finlets might be considered a sort of rocket propeller.
Yes! I believe that's what the others are trying on the Starstreak build...the tip will have canards that are canted and the nose will spin...they are hoping for some gyroscopic effect. Still, my point is that let's say a rocket on a string (attached to the nose tip) will very freely spin in the air...MUCH easier than any bearing you will have (and keep in mind the g-forces laterally down the rocket is substantial and that force will be on whatever bearing you have), so the rocket itself will also spin with canted fins (even on bearings) if the rest is built true and you don't try to counter it by canting or angling the leading edge of the rear fins.

Regarding propeller, one of my long range projects is to create a rocket with propellers on both the front and rear...one day.

Regardless, I think spinning parts and bearings on rockets are COOL.
Here's a bit of my research/building...will continue one day once I find a good thrust bearing for the larger roller bearing fiberglass version.
TRF Summer Build Off: SSC - Spiral Spin Can | The Rocketry Forum
Roller bearing test:

##### I don't do spirals
TRF Supporter
Nothing beats a well-set/designed set of fins for stability for our class of rockets.

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