Yes the accelerometer is limited to 4G so that portion of the thrust curve is out of its range
This flight was on an F35W-8, I got the thrust curve in the sims from thrustcurve.org.
On altitude its meters, on acceleration its m/s^2 (SI units)
I weighed it ready-to-fly and got 552g. The propellant mass is only 30g, so I don't think it could have explained the discrepancy (although propellant mass loss calculations are missing from the sim). Earlier the flight data used to match up a lot better with the sims. However, I am confused why the thrust tapers off much later in the accelerometer data rather than the sim.
Yes, I implemented the sim myself in Scilab Xcos so that I could simulate the PID controller:
View attachment 630420
@Nv7 --
You won't be able to integrate accelerometer data to speed and distance traveled if the sensor cannot read real-world acceleration accurately.
As for the motor burn time ...
What is the percent difference between the F35 thrust curve and the same inflection point in the measured acceleration ?
Real world motors are allowed to vary 20% from the certified thrust curves.
What were the launch site temperature and barometric pressure when you flew your rocket ?
A cold motor may not burn the same as a motor tested on a warm day.
Next to last, the 'pressure -to- altitude' conversions assume that the atmosphere is at STP.
Look around here on TRF for posts by
@ihbarddx -- Larry has done some good work on converting pressure altitude to 'density altitude' where launch site temperature is factored in.
Along the same lines,
Richard Nakka's Experimental Rocketry Web Site has empirical data and he provides plug-n-play formulae for temperature correction for pressure -to- altitude.
There are a blips in pressure but they are also evident in your raw accelerometer data between 3.5 and 4 secs.
Could your canard control motor be causing a voltage drop when it deploys ?
HTH ...
-- kjh
p.s. I think your're doing a great job !
After all, this *_IS_* real rocket science your doing from scratch here
p.p.s. As has been discussed before ... if you want useful acceleration data you'll need an accelerometer that can measure higher values.
4-G acceleration is just barely on the edge of 'legal' for an HPR
p.p.s. here is some real data from a Blue Raven in two different rockets showing the difference among inertial altitude, pressure altitude and density altitude
This was a flight on Nov 4 where the site temperature was 76 F and the site pressure was 997 mb:
This was a flight on Dec 30 where the site temperature was 68F and the pressure was 997 mb:
Note how the green lines ( density altitudes ) differ from the red lines ( raw pressure altitude )
Also note that the Inertial Altitude ( blue line ) is meaningless after the drogue is deployed at apogee