authornatronics <natronics@web>2010-12-04 02:03:05 (GMT)
committer Portland State Aerospace Society <>2010-12-04 02:03:05 (GMT)
commit21616c70545370aaecefc75a47eb3c303c9049e2 (patch) (side-by-side diff)
parent1dc1600949550818350b7a0ee38374436eaf02ac (diff)
new ikiwiki does not respect aspect ratio in !img tags anymore. sadface.
Diffstat (more/less context) (ignore whitespace changes)
1 files changed, 8 insertions, 8 deletions
diff --git a/lv2c_launchdata-2010-06-27.mdwn b/lv2c_launchdata-2010-06-27.mdwn
index c68d9c5..e00beea 100644
--- a/lv2c_launchdata-2010-06-27.mdwn
+++ b/lv2c_launchdata-2010-06-27.mdwn
@@ -188,15 +188,15 @@ The [[roll control|rollcontrol]] was only a partial success. The mechanical and
Here is a graph with a comparison of the raw data from the 3 on board computers that had accelerometers. They were all single axis accelerometers aligned vertically. They only capture vertical acceleration and so are only useful from launch to apogee.
-[[!img accel_raw.png size="650x650"]]
+[[!img accel_raw.png size="650x325"]]
Here is the acceleration just during the motor burn. There seems to be an interesting shoulder around the transonic region.
-[[!img accel_burn.png size="650x650"]]
+[[!img accel_burn.png size="650x325"]]
Taking all this data we created an averaged result by putting all the data into 50ms bins:
-[[!img accel_bin.png size="650x650"]]
+[[!img accel_bin.png size="650x325"]]
Download the binned data: [[accel binned.csv]]
@@ -205,17 +205,17 @@ Download the binned data: [[accel binned.csv]]
This was our first launch using [OpenRocket]( as our primary pre-launch simulation engine. Here we compare our recorded acceleration to the simulation. On the whole it did quite well. We suspect that the thrust curve that it had on file for our engine was not very accurate (or at least our motor deviated from it).
-[[!img accel_or.png size="650x650"]]
+[[!img accel_or.png size="650x325"]]
Here is a close up of just during the burn.
-[[!img accel_or_burn.png size="650x650"]]
+[[!img accel_or_burn.png size="650x325"]]
### Velocity
Taking our binned/averaged data we can integrate to find the velocity at each point:
-[[!img velocity.png size="650x650"]]
+[[!img velocity.png size="650x325"]]
### Drag
@@ -223,7 +223,7 @@ After the motor burns out we should be able to find all the forces on the rocket
[[!teximg code="F_d = ma - mg" ]]
-[[!img drag.png size="650x650"]]
+[[!img drag.png size="650x325"]]
Knowing the Drag force, height of the rocket, and velocity of the rocket we can estimate the Cd empirically. We simply solve for Cd.
@@ -231,6 +231,6 @@ Knowing the Drag force, height of the rocket, and velocity of the rocket we can
[[!teximg code="C_d = \frac{2 F_d}{\rho v^2 A}"]]
-[[!img drag_cd.png size="650x650"]]
+[[!img drag_cd.png size="650x325"]]
This technique does not appear to work very well, unless OpenRocket is just very wrong about drag. Which is possible. The technique is very sensitive to having the correct velocity.