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I don't remember the exact source of the 4 MAC rule. My flight dynamics professor said me the rule showing some data (I don't know where she took them), but I have another useful paper about canard...

Yes! You noticed well! I didn't use shear pins and it was an error. Next time I will use them.
The twisting movement was not a negative occurrence. This additional trouble proved that control system...

You can see it in the complete video: fins stop moving at about 40s.
To make things simple I programmed the control system to control the rocket for 35 second. After this time control fins are...

Here are some photos:
PCB making
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3D
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Contol system (right) plus altimeters: gwiz LCX and Kalmalt (Homemade barometric recording altimeter with Kalman filter)...

No, for roll control I used only the roll axis of the gyro: roll speed is filtered by a Kalman filter to remove noise and sent to a PID controller. The 6DOF study I made was to tune the PID...

Another time thanks to all.

Sampo, I know you for OpenRocket. Great program! I read your degree thesis a couple of time.
I saw thase video on this forum some times ago. How much large were canard...

Data from my flight aren't reliable because I used slightly different propellant reload. In theory the rocket should go higher because when spinning, the fins produce a lift and then an induced drag....

Thanks to all!


Unfortunatly it isn't so easy, because the electronic is made for that fins, and the fins are designed on that specific rocket


no it is in italian!

Yesterday I took my master's degree in Aerospace engineering with thesis of the video below.
I'm Italian and my english in not the best. Could you review all text in the video and the description...

They came with PML kits.
No, it isn't a shipping error because on each chute the size is written by factory. All four PML chutes I have got has the same mismatch!

I have 4 Public missiles parachutes, but nominal dimension doesn't match with read dimension.
For example my 48" chute measure only 42" from angle to angle.
The big question is: WHY?

Thanks

Yes, but my intruder weights 79oz without motor and the motor is an I class sugar motor that weights other 25oz (10oz of propellant).

Altimeter data are not very accurate and show some oscillations, but descent speed is clearly from 7 and 6 m/s, rocket mass was 2.3kg (without propellant), so Cd is between 0.79 and 1.08.

Thanks darisd!
I have an idea! I can calculate the real Cd from my altimeter data! When descent speed is constant, this means that drag is equal to m*g, and so Cd=2*m*g/(ro*V^2*S) where m is the...

Yes I'm using a dual deploy burrito technique. I have a lot of experience with it and I also made a little article for the italian rocketry forum:...

Ok, thanks.
Another small question: is rocksim (I have the old v.7) descent speed quite accurate? Can I trust in it?

Thanks another time

On monday I'm going to launch my Public missiles Intruder wich is strongly modified (it is heavier than a normal Intruder).
It weighs 2.6kg (5.7lb) and I have two choices:
1) Use the original 36"...

Don't worry. Water is not a good electrical conductor, and altimeter voltage is very low. Wash it with dilled water and then, if you have it, use a contact cleaner, like this:...

After some experiments I concluded that pendulum works well, but results are not very accurate because it is difficult to measure exactly the distance between CG and suspension point. Torsion wire is...

Yes I know. I'm using nearly imperceptible oscillations to avoid the error of linearization (when is assumed that sin(alpha) is almost equal to alpha).

I don't like torsion spring beacause it...

If you read well, the article is saying that centroid of area and center of mass overlap only if the object has a uniform density. So, said in other word, the theorem referred to masses...

No, fortunately it doesn't
http://en.wikipedia.org/wiki/Parallel_axis_theorem
It can be understood from the proof.

Yes, but using Huygens-Steiner theorem you can move the reference point and then find the moment of inertia around the roll axis.

Thanks to rocketguy101 for these useful papers.

I need it for a degree thesis in aerospace engineering, so high levels of accuracy are requested. An approximate model is not suitable and using CAD is difficult because I would weight and measure...

I have to find the real roll moment of inertia of a rocket. How can I do?
I think that a manner is to roll the rocket along a inclined plane, measure the time and then obtain Ix with physics....

Not yet. I think it will be really ready in a month.

It was born!
This is the first prototipe ready for the test flight with a quick and dirty PCB. It's dimensions are 90x30mm.
I called it KalmAlt that is altimeter with Kalman filter :D
...

Simply I haven't an acceleration sensor :D. I use only pressure sensor.

Some news.

I finished and debugged the earth of the software using Proteus and MPLAB SIM. Input data for the simulation cames from real flights.

Data storage is at 256Hz until drogue ejection....

I have some EEPROM at home so I'm using them, and I don't have problems at 256Hz sampling.

Congratulations for your first test! I saw photos on argos website few minutes ago.