Taking a shot at the G record

[Adrian A]

View attachment IMG_1959.mov

 

[James Keller]

Can't believe that made it to 10k plus!!! That's some serious skill! Are you attempting the G record today as well?

 

[Adrian A]

Can't believe that made it to 10k plus!!! That's some serious skill! Are you attempting the G record today as well?

Thanks! No G attempt today. Based on this flight the G would exceed the waiver by a lot, so I’ll quit while I’m ahead.

 

[bad_idea]

Congratulations, Adrian. Especially impressive that you had a full airframe. Well, actually everything about this rocket and flight is impressive.

 

[Adrian A]

Recovered without a scratch. After crashing so, so many rockets this year I was beginning to wonder if I am just incompetent at flying rockets. It’s gratifying to have one go better than planned.

 

[Adrian A]

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Data recorded from the GPS tracker. 10,136 feet AGL if I calculated correctly as I walk back to the car. I’m happy to have cell service out here in the middle of nowhere.

 

[bad_idea]

Data recorded from the GPS tracker. 10,136 feet AGL if I calculated correctly as I walk back to the car. I’m happy to have cell service out here in the middle of nowhere.

That exceeds the existing G record by 43 feet!

 

[pugachu]

Great job, Adrian!

The crazy thing about it is that the rocket wasn't even made for the F10! It's a few inches longer than it needs to be. Im really looki g forward to the G12 flight!

 

[kjhambrick]

Great job, Adrian!

The crazy thing about it is that the rocket wasn't even made for the F10! It's a few inches longer than it needs to be. Im really looki g forward to the G12 flight!

Yes !

10k feet on an F-motor had me wondering if maybe Adrian didn't mix up his F's and G's

-- kjh

 

[Adrian A]

I’m not sure what I’ll be able to change in the sim to match this flight’s results so I can predict the G12 altitude. None of my F10 sims went this high.

 

[kjhambrick]

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Data recorded from the GPS tracker. 10,136 feet AGL if I calculated correctly as I walk back to the car. I’m happy to have cell service out here in the middle of nowhere.

Woo Hoo !!!

Congratulations Adrian !

-- kjh

 

[kjhambrick]

I’m not sure what I’ll be able to change in the sim to match this flight’s results so I can predict the G12 altitude. None of my F10 sims went this high.

Yes, I have been following along with an OR Sim and I could only get 8900 ft for a similar rocket on an F10.

My G12 Sim went 14.7k ft and I think it is too low given the F10 flight.

What was your weather like at the launch site ?

-- kjh

 

[Adrian A]

Yes, I have been following along with an OR Sim and I could only get 8900 ft for a similar rocket on an F10.

My G12 Sim went 14.7k ft and I think it is too low given the F10 flight.

What was your weather like at the launch site ?

-- kjh

No wind, no clouds, about 40ish F. 8800 feet pad altitude.

 

[kjhambrick]

No wind, no clouds, about 40ish F. 8800 feet pad altitude.

Hmmm ...

The actual site atmosphere would be denser than the air I sim'd ( 85F and 8900 ft MSL ) but I did sim with a 10 mph wind.

When I changed the site atmosphere as above with no wind, OR sims the F10 to 8,733 ft instead of 8,928 ft and the G12 goes a tad lower to 14,610 ft instead of 14,668 ft.

I'll stop now

Congratulations on a great flight, Adrian !

-- kjh

 

[Adrian A]

I think I found the missing sim parameter in RASAero. The nozzle exit diameter input is used to simulate the elimination of the base drag where the motor plume is. The exit diameter of the motor itself is only about 0.2”. But if the motor eliminates the base drag for the whole tailcone exit area while the motor is burning (and the F10 has an 8 second burn) then the sim goes up over 14kft.

 

[boatgeek]

I think I found the missing sim parameter in RASAero. The nozzle exit diameter input is used to simulate the elimination of the base drag where the motor plume is. The exit diameter of the motor itself is only about 0.2”. But if the motor eliminates the base drag for the whole tailcone exit area while the motor is burning (and the F10 has an 8 second burn) then the sim goes up over 14kft.

Sounds like you could tweak that exit diameter to dial in the sim altitude to match the F10 then use the same answer to estimate altitude for the G?

 

[Adrian A]

That’s what I was thinking. When I do that, the sim is 15,400 16,965on the G12.

Edited: I hadn't applied the tailcone area change for the 15,400 ft result

 

[kjhambrick]

Adrian --

I imagine you're in decompression mode and you've got flight data to compare to your sims before you fly your G12, so no hurry, but before I forget to ask ...

Looking at your recovery pictures, your redesigned boat tail made it thru the F10 thrust phase without any damage at all.

You mentioned in Post #55 that you used a larger nosecone to make your boat tail:

A couple of days ago I found a larger nosecone that I used to cut out a more traditional boat tail. This one tapers down to 0.95" diameter over 0.9" length.

Do you mind sharing the details of your boat tail when you can get to it ?

Thanks !

-- kjh

 

[Adrian A]

I've been doing some analysis of the flight data.

First up is the altitude graph.



Zooming in on apogee:


The Blue line is the raw reported baro altitude using the on-board sensor, and converting pressure to altitude using the standard atmosphere model. The standard atmosphere model is a set of equations that is intended to represent the average atmosphere over all seasons and latitudes. It typically under-estimates altitude for U.S. latitudes during seasons we normally fly, and the warmer it is, the more it underestimates.

NOAA flies weather balloons from dozens of locations across the country, twice per day. These weather balloons carry a GPS receiver to measure altitude and winds aloft, and pressure, temperature and humidity sensors. You can look up the data from these balloons here:
https://weather.uwyo.edu/upperair/sounding.html
For this analysis I used the Grand Junction CO weather balloon data for October 15 12:00 UTC (6 AM local time). Using this data, the balloon-based baro altitude in the orange line matches pretty well with the on-board GPS data.

The on-board GPS data is the most accurate and reliable of the measurements for this flight. The GPS receiver had a lock pretty much throughout the flight, and was tracking 15 satellites before, during and after apogee. This is the measurement that the records committee will use if they accept the record application

The third independent sensor is the inertial navigation estimate derived from the accelerometer and gyro data. This estimate depends on the validity of the acclerometer calibration and linearity, and the attitude calculated from the gyroscopes. For this flight, the gyro sensors hit the rail partway at the end of the burn:


Despite that, the inertial navigation estimate agreed with the onboard GPS within about 3.8%, which IMO is pretty good.

 

[Adrian A]

Here's the flight in Google Earth:



A very straight ascent, and pretty strong upper-level winds. The first part after apogee had a descent rate of about 25 feet/second and a horizontal velocity of 75 feet/second. The descent rate was pretty constant, starting at 28 feet/second and going down to 22 feet/second near landing when the air got thicker.

 

[Adrian A]

Here's the tilt:

Each of the little bumps corresponds to a roll rotation. If the measurement of initial motion at liftoff detection were better aligned with the actual rocket axis those bumps would be reduced.

Below are the accel measurements:



The yellow is pretty close to the rocket axis. The red and blue are lateral axes that measuring the centripetal acceleration from the rocket spin.

 

[NTP2]

I am afraid of that thing on a G12…

 

[kjhambrick]

Wow !

What an amazing flight !

Thanks for the GREAT data plots and analysis, Adrian !!

Does anybody know if there a good online source where I can learn to interpret the google map.kml plots ?

I've been reading this: Google: KML Tutorial but it is more a developer doc than something for a mere consumer of the plots.

Thanks again !

-- kjh

 

[SolarYellow]

Try Google Earth

 

[tim cubbedge]

Maybe I missed it but how far was recovery from the pad?

 

[Adrian A]

Maybe I missed it but how far was recovery from the pad?

3 miles.

 

[cwbullet]

Thanks! No G attempt today. Based on this flight the G would exceed the waiver by a lot, so I’ll quit while I’m ahead.

Find a new waiver.

 

[boatgeek]

Thanks! No G attempt today. Based on this flight the G would exceed the waiver by a lot, so I’ll quit while I’m ahead.

Did you get any ruling from the RSO/management at that club about whether they'd accept a Class 1 flight above their waiver during a regular waivered launch? If not, would they be willing/able to host a Class 1 launch at the site on a day that's not a regular launch day?

 

[Adrian A]

Did you get any ruling from the RSO/management at that club about whether they'd accept a Class 1 flight above their waiver during a regular waivered launch? If not, would they be willing/able to host a Class 1 launch at the site on a day that's not a regular launch day?

Find a new waiver.

If NCR November launch isn't cancelled, I'll launch it then. If it is cancelled I may just wait until next Spring, along with 2-stage record attempts. I could go to Texas or Phoenix before then but I'm not in that big of a hurry. And I'm curious to see if the Tripoli records committee accepts my application for the F record that I sent in yesterday.

 

[FredA]

3 miles.

So, was this outside the waiver cylinder?
Cool flight and awesome analysis, but keeping it in the park is vital.
Not sure about your launch site, but 3 miles away is almost always too far.