Two-stage P to O Space Shot attempt at BALLS 30

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How did you machine the interstage? For perfect nozzle matching, did you have to make test pieces?
The easiest approach is that when you set the angle on a lathe compound rest you turn the nozzle and the transition cone one after the other. That way you are sure that both have the same angle. For example in practice I do the nozzle first, but I leave some material (a few milimeters) on the divergent expansion cone. Then I turn the interstage and I also leave some material on the mating cone. Then I set the angle on the compound rest and I do a couple of final passes on both parts. That way they are made to the same angle and the fit is perfect. I attached a hand made drawing of a transition cone, so you can get a rough idea how does it look like. This drawing if from a smaller two stage rocket, but the principle is the same.

Skica- Adapter.jpg
 
HTPB as opposed to PBAN I guess judging by curing times and no mention of a curing oven? Or was it PBAN? Just ask'in.
Yes, it was HTPB.
 
Andrej, if you're inclined to share, I'd be curious to know what the roundtrip cost of shipping your Big Box from Europe to Black Rock and back was.
The big shipping box we sent to US was not just for us. There was a large group from Vienna, two of us and two more guys from Poland and Austria. We all shared the space in the box and divided the shipping cost. We also didn't send anything back. The things we did take back were put in personal luggage. Just for our project the cost of shipping was about $1600.
 
Did you have any mechanical connection between the booster and sustainer other than the matched cone/nozzle? Did you need to blue the pieces to get a solid fit?
No, there was no additional mechanical connection. This two pieces are made like I described three posts before. I just machine both cones (nozzle expansion cone and transition cone) to exact same angle. That's basically the same thing as Morse taper on a lathe.
https://en.wikipedia.org/wiki/Machine_taper
 
Overall, this is an extreamly impressive project (obviously). The idea of coming to a foreign country, mixing propellant, etc., is just over the top. As a project manager, what I admire most about this project is the project management aspect - getting all of the logistics together to execute the project on schedule. Well done!

Regarding the recovery of the rocket, and speculating at best, I think it might be possible that the rocket came in ballistic. When I do simulations of a simular rocket, it appears that on a ballistic recovery, the rocket will be slowing down as it nears the ground. The velocity at impact would be close to the 1760 ft/s CoCom limit. So, it is possible that the rocket slowed down just enought to allow a Featherweight packet at 2 Km altitude. I note from the description of the flight that the Featherweight packet occurred "a few minutes later". A ballistic recovery would have taken about 6 minutes or so, but if a drogue had come out, the time would have been more like 10-15 minutes. It doesn't sound like that much time had expired? This is just speculation, but it sort of fits the data. One question I would ask is how was the rocket separated at apogee?

Another question I have is about the apogee charge at 163 seconds. What triggered this charge? Time or inertial altitude?

Last question. How were you able to raise the rocket using Tony's pad? That must have been interesting!

Again, you did a great flight. Looking forward to the next try!

Jim
 
No, there was no additional mechanical connection. This two pieces are made like I described three posts before. I just machine both cones (nozzle expansion cone and transition cone) to exact same angle. That's basically the same thing as Morse taper on a lathe.
https://en.wikipedia.org/wiki/Machine_taper
Careful when doing this that the two pieces don't lock like the Morse tapers do. It depends on materials and the coefficient of friction between them. If I recall correctly, if the angle is wider than the inverse tan of the coefficient of friction it will not lock together. I have used this on interstage connections.

The easiest approach is that when you set the angle on a lathe compound rest you turn the nozzle and the transition cone one after the other.
A lot of people forget this and try to do it by resetting the compound angle later. Much easier to do, as you mention, when it is undisturbed.
 
There is a chance that another rocket carrying a Featherweight Tracker at altitude may have picked up a lost rocket packet from yours after landing. It sounds like your last packet may have been just before the line of sight from your ground station was obstructed by the mountains. Other rockets flying later could have had an unobstructed view. On my 2 flights at BALLS I picked up landed locations for 4 “lost” rockets, with rocketIDs of Huet-Rkt02, SEvesO2430, Alex Trkr, and SN53. What was your rocket ID? If Featherweight users who were there open up the Featherweight Inferface Program and check under More/Found, they might have the coordinates.

This is perhaps a dumb question, but could someone put the tracker on a drone and send the drone to the last known position before ground track was lost and likely get a new position (same day as launch, not today)? I never would have thought of the tracker for other rockets would be able to pick up packets from other rockets. If this was a design decision - WOW - you got a big brain!!!

I didn't see if @Andrej posted the tracker name or not, but if not hopefully he can post it and other fliers will check their logs. How awesome if these rockets could be recovered and final data gathered!

Sandy.
 
This is perhaps a dumb question, but could someone put the tracker on a drone and send the drone to the last known position before ground track was lost and likely get a new position (same day as launch, not today)? I never would have thought of the tracker for other rockets would be able to pick up packets from other rockets. If this was a design decision - WOW - you got a big brain!!!

I didn't see if @Andrej posted the tracker name or not, but if not hopefully he can post it and other fliers will check their logs. How awesome if these rockets could be recovered and final data gathered!

Sandy.
Yes one could very much do that (mount another tracker on a drone to find a lost rocket. Adrian is a really smart guy for sure! I hope @Andrej checks out the screens above with tracker names and hopefully he can find it.
 
Yes one could very much do that (mount another tracker on a drone to find a lost rocket. Adrian is a really smart guy for sure! I hope @Andrej checks out the screens above with tracker names and hopefully he can find it.

I hope we can get the word out to anyone who had a Featherweight tracker at the event to check and see, even if they aren't on this forum. If Andrej can post the name, hopefully we can get the word out.

I can only imagine there are quite a few people who would volunteer to go look for it if they had a likely chance for documenting the recovery. In all fairness, I'm not that guy, (East Coast) but I hope there are some locals that could go if the position somehow became known.

Sandy.
 
I hope we can get the word out to anyone who had a Featherweight tracker at the event to check and see, even if they aren't on this forum. If Andrej can post the name, hopefully we can get the word out.

I can only imagine there are quite a few people who would volunteer to go look for it if they had a likely chance for documenting the recovery. In all fairness, I'm not that guy, (East Coast) but I hope there are some locals that could go if the position somehow became known.

Sandy.
Rockets have been found doing this up to 2 weeks after the flight.

https://www.rocketryforum.com/threads/lost-rocket-at-balls-2022.175109/
Tony
 
I hope we can get the word out to anyone who had a Featherweight tracker at the event to check and see, even if they aren't on this forum. If Andrej can post the name, hopefully we can get the word out.

I can only imagine there are quite a few people who would volunteer to go look for it if they had a likely chance for documenting the recovery. In all fairness, I'm not that guy, (East Coast) but I hope there are some locals that could go if the position somehow became known.

Sandy.
Only issue is that last time i flew a drone, admittedly close to 2 years ago, you can only fly up to 400 ft AGL. That wouldn't do you very good around that launch site, with the mountains and all (for LOS reasons). Maybe would do well in flat launch area.
 
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The easiest approach is that when you set the angle on a lathe compound rest you turn the nozzle and the transition cone one after the other. That way you are sure that both have the same angle. For example in practice I do the nozzle first, but I leave some material (a few milimeters) on the divergent expansion cone. Then I turn the interstage and I also leave some material on the mating cone. Then I set the angle on the compound rest and I do a couple of final passes on both parts. That way they are made to the same angle and the fit is perfect. I attached a hand made drawing of a transition cone, so you can get a rough idea how does it look like. This drawing if from a smaller two stage rocket, but the principle is the same.

View attachment 542135
In addition to being a good machinist, that is beautiful hand-made drawing. With the overwhelming prevalence of CAD, you have a rare and slowly vanishing talent! When I was in junior high school (7th-8th year) all boys were require to take at least half a year of mechanical drawing. Those were the days! old.gif
 
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This is perhaps a dumb question, but could someone put the tracker on a drone and send the drone to the last known position before ground track was lost and likely get a new position (same day as launch, not today)? I never would have thought of the tracker for other rockets would be able to pick up packets from other rockets. If this was a design decision - WOW - you got a big brain!!!

I didn't see if @Andrej posted the tracker name or not, but if not hopefully he can post it and other fliers will check their logs. How awesome if these rockets could be recovered and final data gathered!

Sandy.
Yes, if the drone gets high enough to have a clear line of sight. Or you could launch a simple rocket carrying a tracker that gets up to 10k-20k to see over all the nearby mountains. The "lost rocket" transmissions are at a higher data rate for shorter packets, so the range isn't quite as far as the paired GS/Tracker transmissions, but it should still have a lot of margin for this purpose. This scenario of a big rocket landing over a mountain range at BALLS is exactly the use case that I designed this feature for, and it will get better when the app is updated to make it easier to see when lost rocket packets come in. This 1-hop relay approach, and a lot of the hardware and software, was also used for the data return capsules for NASA's LOFTID program, which is set to launch next month. For this program we tested the ability use over-the-horizon relay on a tracker attached to a high-altitude weather balloon to find capsules bobbing in the ocean from up to 70 km away.
 
Yes, if the drone gets high enough to have a clear line of sight. Or you could launch a simple rocket carrying a tracker that gets up to 10k-20k to see over all the nearby mountains. The "lost rocket" transmissions are at a higher data rate for shorter packets, so the range isn't quite as far as the paired GS/Tracker transmissions, but it should still have a lot of margin for this purpose. This scenario of a big rocket landing over a mountain range at BALLS is exactly the use case that I designed this feature for, and it will get better when the app is updated to make it easier to see when lost rocket packets come in. This 1-hop relay approach, and a lot of the hardware and software, was also used for the data return capsules for NASA's LOFTID program, which is set to launch next month. For this program we tested the ability use over-the-horizon relay to find capsules floating in the ocean from up to 70 km away.

Wow! So you're working on the ability for a rocket in the air to relay the data for a rocket behind the hill to report out?!?!?! I had no clue - guess I need to get up to speed with what you're working on now, as you seem to keep raising the bar.

For the forum, I was an early adopter of the Raven, before it was called the Raven 1, just the Raven. It nailed exactly what I was looking for with regard to both a dual deploy along with data logging in a tight package. As an early adopter, I needed a bit of support from Adrian and it was awesome. I was also an early adopter of his screw switches and they are still my standard.

I haven't been flying many electronic flights for quite a while, but I imagine my Raven will be quite fine. Having said that, it sounds like the state of the art is moving way beyond what I ever would have expected! Sounds like I need to learn more and I know where I need to look!

Awesome stuff!

Sandy.
 
Also, if someone does get a found rocket packet, I would recommend that the GPS coordinates be shared privately. By necessity lost rocket coordinates are shared to other participants in-person at the launch, but if it were my rocket that hadn't been recovered yet, I would prefer the coordinates not be posted on public forums until I had a chance to coordinate the recovery effort.

The last received packet should also have horizontal and vertical velocity, and heading information, which can be used to extrapolate the final location.

The lost rocket transmissions start after a landing is detected by the tracker and the tracker hasn't heard an acknowledgment from the ground station or over Bluetooth from the phone for 5 minutes. Transmissions on the lost rocket channel stop automatically when either the GS or the phone gets in range again.
 
One question I would ask is how was the rocket separated at apogee?
It had two aluminum ejection canons, first firing at apogee and second 2 seconds later.

Another question I have is about the apogee charge at 163 seconds. What triggered this charge? Time or inertial altitude?
It was triggered by accelerometer. We figured we will try with accelerometer, because even if it detected apogee early or late that wouldn't make much difference at that altitude.

Last question. How were you able to raise the rocket using Tony's pad? That must have been interesting!
It was easier than expected. First the booster was loaded on the rail, then sustainer was attached to the interstage (at the front end it was supported with a piece of wood) and secured with a rope. We had two friends there to help, so the three of was lifted the rail and rocket to vertical and the fourth inserted the locking pin when it was upright. Altogether took only about ten minutes.
 
I wonder if the tracking problem here would be a good reason to have a redundant tracker that is just a RF beacon for use with direction finding.

Over engineered idea #1 - have the tracker enable an output to turn on the RF beacon if it loses contact with a base station.
 
The TeleMega has a 50mW? 70cm transmitter that can be used to RDF the signal regardless of whether or not GPS has lock.
 
Yes, if the drone gets high enough to have a clear line of sight. Or you could launch a simple rocket carrying a tracker that gets up to 10k-20k to see over all the nearby mountains. The "lost rocket" transmissions are at a higher data rate for shorter packets, so the range isn't quite as far as the paired GS/Tracker transmissions, but it should still have a lot of margin for this purpose. This scenario of a big rocket landing over a mountain range at BALLS is exactly the use case that I designed this feature for, and it will get better when the app is updated to make it easier to see when lost rocket packets come in. This 1-hop relay approach, and a lot of the hardware and software, was also used for the data return capsules for NASA's LOFTID program, which is set to launch next month. For this program we tested the ability use over-the-horizon relay on a tracker attached to a high-altitude weather balloon to find capsules bobbing in the ocean from up to 70 km away.
Off topic a bit, but I love your trackers. I have a few and they are really nice. I also think your passion for rocketry is extra special too. Thanks for making great hardware that we can buy and enjoy!
 
I have 11 'found' trackers in my iFIP list from BALLS 30, but unfortunately none named Karman-1 or Karman-2. But I do have the same one that Tony (TFish) had in that lost rocket thread - 'Alex Trkr' in my list. Great example of how well the lost rocket feature can work.

I'm thinking that I should change the name of my trackers to my cell number plus a letter - much easier for someone to track me down.


Tony
 
This September at BALLS 30 me (Andrej Vrbec) and my friend Denis Banovic flew a two stage project. Since we are from Europe we packed all the rocket parts, tools and supplies in a big box and sent it across the ocean with cargo freight. We arrived in Reno one week before BALLS and rented a garage there. In the next three days we processed more than 180lbs of propellant and casted four motors- two boosters and two sustainers. Booster motor is a P motor, is 150mm in diameter and has 30kg (66lbs) of propellant. Sustainer motor is an O motor, is 100mm in diameter and has 11kg (24lbs) of propellant. All the motors are case bonded, monolithic grain type. Booster motor has a six-point star geometry and a faster burning propellant, while the sustainer is a simple core burner with a slow burning propellant. Thermal insulation/inhibitor was spin-cast in the casing a few hours before propellant was poured in. Since the flame zone gets in touch with the casing wall only at the very end, the casing insulation is relatively thin- 1mm for the booster and 0,5mm for the sustainer. Propellant was designed so that it can be processed on the field, with as little equipment as possible. Ridgid paddle mixer from Home Depot equiped with a custom made mixing paddle was used for mayority of mixing. After curative was added the propellant was mixed in a compact vacuum mixer that I built myself. The same Ridgid mixer was also used to turn the spin casting setup for thermal insulation. Off course having a propellant that is pourable and easy to work with, also means it can't have very high solids loading. That took some toll on the Isp, but in the end it worked out pretty good. Booster propellant had 80% solids loading and the sustainer 78%. My biggest concern was that AP that we bought in the US will have different particle
What was your propellant mass fraction for your motors, that is, the ratio of propellant to the case mass, excluding additional fittings mass?

Robert Clark
 
- Booster burned out and separated at an altitude of 3,5km and Mach 2,4
- Sustainer then coasted for 11 seconds and reached an altitude of 10km
- Sustainer motor ignited and burned out at an altitude of 20,5km and Mach 4,9
- Apogee charge was fired after 163 seconds
- After 4 minutes of flight telemetry was lost

High altitude ignition for the upper stage has been a problem for other teams, how did you accomplish it?

Bob Clark
 
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