Medium performance 2-stage rocket, second try!

[JEtgen]

Seeking Clarity II (That's the rocket's name... the idea was to get a flight above 50K AGL, up where the air is clear, and it's a stepping stone to 100K+)

So, last year we tried to accomplish that, but didn't make it due to some still unresolved issue with getting the flight computer in charge of staging to fire as expected.

We tried again this year. I had to rebuild the sustainer, and I decided to build a new booster as well, increasing the size motor it could take, just to have a better shot at breaking 50K. Also, we switched to using the Blue Raven to control staging. We had several successful smaller 2 stage flights over the winter flying season that built our confidence that we knew what we were doing with that system. Adrian was also super helpful in giving us advice and talking us through any small issues we found. (And we did find one at Airfest where a scaled down version of this flight failed to light the sustainer).

So, the flight motors were a research N2200-ish to a modified Loki K350 moonburner. The modification was to the forward bulkhead to allow headend ignition.

Here's Stu Barrett hooking up the igniter clips as we are just about ready to retreat back to the flightline. (sorry if that pic is out-of protocol big)


Here's some of the flight data, up to apogee recorded by the back-up flight computer (Telemetrum)



So... YES! we got it, just over 53,000 AGL as recorded by GPS. I will have some liftoff pics later, and I have a crappy out-of-focus iphone video that I will see if I can improve before posting.

The only thing that didn't work was the crappy onboard video camera. That thing is going in the trash.

John and Jenni

 

[lr64]

Wow! That's MEDIUM performance????

 

[pugachu]

Nice! Did everything recover nicely, and able to fly again?

 

[JEtgen]

Nice! Did everything recover nicely, and able to fly again?

Yes, booth booster and sustainer recovered nominally.

 

[JEtgen]

Wow! That's MEDIUM performance????

Well, in my book, yes. A truly high-performance 2 stage rocket in those motor classes would have gone higher and faster. I never broke Mach 2 anytime in the flight and I staged (well, lit the sustainer) subsonic, just to be safe. The booster is pretty heavy for its size and length, and I didn't do anything edgy in the booster motor design.
The loki K350 is probably pretty well optimized, but that is credit to Scott K., not me.

 

[Spacedog49Krell]

I look forward to seeing the Blue Raven data. You have interesting acceleration data as the N motor burns out, could be some grain breakup. Also, your supersonic to subsonic transition data for both stages looks interesting. Great flight.

 

[cerving]

Congratulations! Man, that's one long delay between burns... like 12 seconds. Pretty rocket, too!

 

[jkovac]

The only thing that didn't work was the crappy onboard video camera. That thing is going in the trash.

Congratulations on the flight!

What was the crappy onboard video camera that didn’t work?

 

[JEtgen]

The onboard camera was a "Muvi" which is similar form factor as the "insta go 360" cameras that others have used successfully. Not sure why it quit recording shortly after buttoning everything up. But that's what it did..

On the good side, a friend of Scott Kormeier did manage to catch a good video of the flight. I appologize for not remembering his name, I think his name was Mark, but I forgot his last name. I hope he is OK with me posting the video which he graciously gave us a copy of. Our normal camera man slept in late and didn't have his act entirely together that morning.
View attachment IMG_5611.MOV

 

[JEtgen]

I look forward to seeing the Blue Raven data. You have interesting acceleration data as the N motor burns out, could be some grain breakup. Also, your supersonic to subsonic transition data for both stages looks interesting. Great flight.

I think that little positive acceleration blip right before max downward acceleration was the separation charge. All the grains were glued in with glue-all max. It seems that all of the commercial flight computers will detect MECO a little early, typically right at the 0-acceleration point. For a slow flight, that might be the right thing to do. But when you are going 1700+ fps, the motor is still producing non-trivial thrust even when it seems like you are coasting because drag is probably 3-5 g's worth in the opposing direction. I was actually trying to allow for that in the programming as I had the separation charge fire 1 second after MECO. I was still just slightly early, but close enough.

Stu Barrett was telling me I was nuts for waiting until I was solidly subsonic to light the sustainer. What do you all think? Should I have just lit the sustainer a few seconds after MECO and stayed supersonic?

 

[JimJarvis50]

Dang, I missed your great flight. Just didn't arrive quite in time.

Jim

 

[JEtgen]

Congratulations! Man, that's one long delay between burns... like 12 seconds. Pretty rocket, too!

Thanks! We used the feature in the Blue Raven to coast down to a set velocity as the trigger for sustainer ignition. The safeties were set as 1) must achieve 5000 feet altitude (and a nominal flight would be well over that) 2) max tilt at current time <22 degrees (I allow for a little wobble in the tilt data due to not quite perfect alignment of the board) 3) max historical tilt <30 degrees (that's to prevent some odd scenario where it does something bad, but momentarily comes back into conformance with conditions 1 and 2.

So, yes, the coast time can be pretty long. At least in simulation, that is the way to get the best altitude, assuming you have a nominal and reasonably vertical boost. The weather was SO good, that I was willing to take that risk.

 

[JEtgen]

Yes, booth booster and sustainer recovered nominally.

Here's Jenni with the booster, which landed about 200 yards off the west end of the flight line for a totally easy recovery


And here is Jenni and our camera man Joe Dellinger at the sustainer landing point, about 2 miles NW of the flight line, about a mile past the away cells.


Here's the sustainer barometric data for the whole flight. The descent under drogue from 53K takes a LONG time! The descent under main looks like such a small portion of the flight, and I deployed the main at 3,000!

 

[kjhambrick]

Congratulations, John and Jenni !

Thanks for all the data and the pics and the video.

Beautiful flight -- the ignition delay on your sustainer was certainly ... suspenseful !!

And she landed pretty close on the playa !!!

It is nice to see Stu out there too.

Stu Barrett was telling me I was nuts for waiting until I was solidly subsonic to light the sustainer. What do you all think? Should I have just lit the sustainer a few seconds after MECO and stayed supersonic?

I sure wouldn't second-guess your success -- 53K ft AGL is nothing to sneeze at -- way higher than anything I've ever done or will ever do

Thanks for sharing.

-- kjh

 

[Spacedog49Krell]

I think that little positive acceleration blip right before max downward acceleration was the separation charge. All the grains were glued in with glue-all max. It seems that all of the commercial flight computers will detect MECO a little early, typically right at the 0-acceleration point. For a slow flight, that might be the right thing to do. But when you are going 1700+ fps, the motor is still producing non-trivial thrust even when it seems like you are coasting because drag is probably 3-5 g's worth in the opposing direction. I was actually trying to allow for that in the programming as I had the separation charge fire 1 second after MECO. I was still just slightly early, but close enough.

Stu Barrett was telling me I was nuts for waiting until I was solidly subsonic to light the sustainer. What do you all think? Should I have just lit the sustainer a few seconds after MECO and stayed supersonic?

I did a quick optical overlay of your TeleMetrum data, focusing on the small acceleration blip at the N motor burnout. After comparing the acceleration and velocity slopes between booster burnout and sustainer burnout phases of the flight, I'm left with more questions about the separation charge separating the stages. As you mentioned, the burnout thrust is non-trivial and the charge fired at a high Q pressure point during the flight. Check the high-rate data file of the Blue Ravin.

12 seconds is not long. I have a 2-stage G that requires a 6 second stage delay for maximum altitude.

 

[pugachu]

What casing did you use for your N motor? Just curious as to the approximate total N*s

 

[JEtgen]

What casing did you use for your N motor? Just curious as to the approximate total N*s

It's a John Lyngdal (sic?) case, ~45 inches long and can take 39 inches of propellant. Probably around 14K Nsec, depending on how good a job I did with the propellant.



I can put more details over in the Research section if you like.

 

[pugachu]

It's a John Lyngdal (sic?) case, ~45 inches long and can take 39 inches of propellant. Probably around 14K Nsec, depending on how good a job I did with the propellant.



I can put more details over in the Research section if you like.

I've only dabbled in EX hybrids and sugar motors, I was just curious as to the performance of the rocket.

 

[JEtgen]

I did a quick optical overlay of your TeleMetrum data, focusing on the small acceleration blip at the N motor burnout. After comparing the acceleration and velocity slopes between booster burnout and sustainer burnout phases of the flight, I'm left with more questions about the separation charge separating the stages. As you mentioned, the burnout thrust is non-trivial and the charge fired at a high Q pressure point during the flight. Check the high-rate data file of the Blue Ravin.

12 seconds is not long. I have a 2-stage G that requires a 6 second stage delay for maximum altitude.

You might be on to something... When I look at the data for the booster and the sustainer together, at 5.743 +/- a few milliseconds there is clearly an upward acceleration of the sustainer and a downward acceleration of the booster. I am pretty sure that is the separation charge doing "something" . About 15 ms before that, there is some evidence that maybe there was a partial drag separation. The 2 acceleration curves are not that well correlated. At 5.743, they become pretty nicely anti correlated. So I think it tried to drag separate, and got hung up , maybe slightly cocked in the interstage (yuk), but then separation fired and it was away. At that point the booster is accelerating downward much more than the sustainer, so they were no longer mechanically connected at 5.785 seconds

 

[JEtgen]

Dang, I missed your great flight. Just didn't arrive quite in time.

Jim

You were trying to tackle a really ambitious flight, so I totally understand that you were focussed on that.

I'll just have to do an encore next year!

 

[Spacedog49Krell]

You might be on to something... When I look at the data for the booster and the sustainer together, at 5.743 +/- a few milliseconds there is clearly an upward acceleration of the sustainer and a downward acceleration of the booster. I am pretty sure that is the separation charge doing "something" . About 15 ms before that, there is some evidence that maybe there was a partial drag separation. The 2 acceleration curves are not that well correlated. At 5.743, they become pretty nicely anti correlated. So I think it tried to drag separate, and got hung up , maybe slightly cocked in the interstage (yuk), but then separation fired and it was away. At that point the booster is accelerating downward much more than the sustainer, so they were no longer mechanically connected at 5.785 seconds

I'm not suggesting a mechanical connection, but a shock cone aerodynamic coupling, like NASCAR drafting. I've studied ordnance release behavior up to Mach1.2. I've been at launches where the booster on large 2-stage vehicles separates and flies in formation behind the upper stage for 1-2 seconds. These were subsonic flights. I've wondered about booster behavior when they separate at supersonic speeds. If you have Blue Ravin data for both stages, I would be interested in looking at it.

It's also a pleasure to talk to other fliers about events happening in milliseconds.

 

[kjhambrick]

John and Jenni --

I hope you don't mind that I cloned and marked up your BEAUTIFUL Telemetrum Plot to ask a Q -or- 2 ...

I overlaid a vertical marker line thru the pair of coast-phase transonic transitions:


It is interesting ( at least to me ) to see that the first transonic transition in the troposphere around 11.5k ft, took place when the sustainer was flying at about 1,100 ft/sec

But then the velocity was only anout 950 ft/sec for the 2nd transition up in the statusphere at 42k ft and the effect is dimished up in the thin air ...

But then I am easily amused ...

It would be interesting ( at least to me ) to grab a copy of the Atmospheric Sounding Data set for the region during the flight to see the actual temperatures at altutude for the date / time of your flight ...

Speaking of altitude ... what is the source of the green altitude -vs- time plot ?

Q: Do you know what caused the discontunities at 4-sec and 18-sec ?

Q: As for the positive acceleration blip for the sustainer at about 6-secs ... wouldn't NASCAR drafting behind the sustainer affect the booster ?

Unless maybe there is a kick from a mach shock in front of the booster ( or something ) ?

We need @Buckeye's CFD program !

Anyhow ... Thanks for sharing your experience !

It is almost like being there ( well ... maybe not quite )

+1 for @Spacedog49Krell's request for the three Blue Raven files for the Sustainer and if you have Blue Raven data for the booster, that would be four times as fun to play with !

Thanks again John and Jenni !

-- kjh

 

[Spacedog49Krell]

kjh,

At 4 sec the GPS hit the Mach lockout limit of ~1.5. At 18 sec, the sustainer motor ignition of ~25 G's caused a loss of signal for the GPS. Upon reacquisition of satellite signals it was above Mach 1.5.

NASCAR drafting inversely applies to both cars. The low pressure void behind the lead car sucks the trailing car up to the lead car. The trailing car requires less hp and uses less fuel to stay with the lead car. The lead car will also increase in speed, especially with 2 or 3 drafting cars. The trailing car also becomes more stable and the lead car less stable. I did some amateur racing in my twenties. These same aerodynamic principles apply to our rockets. Now, we all have the means to capture the phenomena and study it instead of a few DIY's.

 

[kjhambrick]

Thanks @Spacedog49Krell !

I wondered about the source of the altitude data because there is no corresponding discontinuity in the velocity -vs- time plot so I was thinking it might be from acceleration -vs- time.

Gotta love the "spooky action at a distance" due to "entanglement"

-- kjh

 

[Spacedog49Krell]

Thanks @Spacedog49Krell !

I wondered about the source of the altitude data because there is no corresponding discontinuity in the velocity -vs- time plot so I was thinking it might be from acceleration -vs- time.

Gotta love the "spooky action at a distance" due to "entanglement"

-- kjh

We have both Quantum and Aggregate entanglement.

 

[JEtgen]

Correct, the altitude data was GPS, hence the lockouts / signal loss stuff. Are you guys wanting data, or just a picture of the data?

 

[Spacedog49Krell]

Correct, the altitude data was GPS, hence the lockouts / signal loss stuff. Are you guys wanting data, or just a picture of the data?

I would like copies of the High and Low speed data files. I look at the fine details that the 2ms resolution the Blue Raven offers.

 

[kjhambrick]

I would like copies of the High and Low speed data files. I look at the fine details that the 2ms resolution the Blue Raven offers.

+1 if you don't mind, John and Jenni !