Attempting the K and L altitude records

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T34zac

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Ever since LDRS ended, I’ve been working on a specific project XPRS this upcoming weekend. The project in question is a 54mm ‘flying case’ rocket designed around the CTI Pro54 6g XL case with the ultimate goal of setting a new Tripoli K altitude record, and possibly setting a new L altitude record a month or two from now.

First thing I got started with was the fin can. I didn’t like the way commercial tubing fit loosely on the motor case, so I decided to make my own tube using an old motor case as a mandrel. I don’t have any good pictures of the process, so here’s the end result instead:


Fins were cut from 1/16” carbon from dragon plate and beveled with a Crazy Jim style beveling jig with 150grit sandpaper
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Fin can is a perfect fit on the case.
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Next up is the attachment method for the upper airframe section. The CTI K300s come with a plugged forward closure that has a1/4-20 threaded insert. My plan is to utilize that to attach the rest of the airframe to the motor using an aluminum adapter piece. I borrowed a friend's mini lathe for a week and spent around 11 hours of machining time making this small piece. One important thing was I put a radius on the underside to as close as possible match the radius of the forward end of the case. It’s not perfectly clean, but it the lathe really didn’t like the large piece (relative to the lathe) that I was working with and struggled every bit of the way.
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Conforming to a Pro54 case.
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Final piece attached to the motor case with a coupler tube added:
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The motor includes 1/4-20 screw, I replaced this with 1/4-20 threaded rod instead.
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The fin can was finished shortly after. Laser cut fin jig was used to align the fins and healthy fillets were used to bond everything in place.
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Moving onto the nosecone. I’ve never attempted to make a nosecone and I wasn’t quite ready to start now. My plan was to modify a filament wound cone from Madcow, to make the base diamerter the same as the fiberglass coupler tube. A 3d printed miter was used To make sure I ended up with a square cut at exactly the right point.
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Since the nosecone no longer has a cylindrical section, a conical shoulder would be needed to mate the cone to the rocket. Again I modified another nosecone to create the needed interface.
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Fitment is extremely important on conical interfaces so it was crucial that I got the shoulder to stick out of the coupler tube the perfect amount. The end result is a joint with no wiggle, but is easy to separate.
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Note, the composite tip of the nosecone was also removed so I could add an aluminum tip later on.

Now to the electronics bay. A Featherweight Raven 4 was selected as the flight computer for this rocket, MissileWorks screw switch for arming/disarming, and a Featherweight GPS for tracking and official altitude verification (record attempts above 30,000’ require GPS data). The Raven, switch, and battery are housed within the coupler tube that’s on top of the motor, and the GPS is going to live in the nosecone with the recovery gear. The sled was 3d printed and secured in place using the central threaded rod and nut.
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Recovery gear is simple on this rocket. Because of the venue (Black Rock), I decided that it would simple and easy to go with single deploy for this rocket. No cable cutter, just main at apogee. A TopFlight 30” thin mill parachute should bring this whole rocket down at about 22-25 FPS, allowing for a nice soft landing about a half hour after apogee. Picture included is the recovery gear, and electronics all packed inside the airframe of the rocket.
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Everything is loosely packed enough that deployment shouldn’t be an issue, but tight enough that the entire usable volume of the rocket is used up.

Expected altitude on the K300 is about 40,000’, but I’d be happy with something around 35,000’.
 
Impressive minimization of weight and profile. I'll be eagerly awaiting the results of your launch!
 
Recovery gear is simple on this rocket. Because of the venue (Black Rock), I decided that it would simple and easy to go with single deploy for this rocket. No cable cutter, just main at apogee. A TopFlight 30” thin mill parachute should bring this whole rocket down at about 22-25 FPS, allowing for a nice soft landing about a half hour after apogee.

Expected altitude on the K300 is about 40,000’, but I’d be happy with something around 35,000’.

I don't see how this recovery profile would land within the confines of the launch area, how are you mitigating this?
 
I don't see how this recovery profile would land within the confines of the launch area, how are you mitigating this?

Salt flats have about a 7-mile X 7-mile recovery area. Seems doable to me.

This will be flying at Black Rock over the weekend. Ideally in the mornings when they have their large waiver/cylinder of 250,000’/15 mile. Assuming a worst case scenario average of 15 mph winds, that puts my landing ~7.5 miles away
 
And here’s the finished rocket put together for its final assembly before heading to Black Rock in a couple days.
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Future plans include:
- L265 at Tripoli Phoenix to attempt the L record (pending success of the K300 attempt)
- K1440 at Tripoli Phoenix, trying to break Mach 3.5 (going to build a new fin can for that)
- K2045 at LDRS 40. I’ve got a friend who has one, and wants to see it on something that’s a “full send”
 
This will be flying at Black Rock over the weekend. Ideally in the mornings when they have their large waiver/cylinder of 250,000’/15 mile. Assuming a worst case scenario average of 15 mph winds, that puts my landing ~7.5 miles away
If you look at the high altitude forecasts, you can see that the winds up there are often significantly above 15 mph, especially if you hit the jet stream. You will probably still stay within BR15, but recovery can turn into a little adventure, if the rocket lands further away. Much of that area out there is not a flat playa.

For what it's worth, I once stayed about 13min in the air at BALLS (descending ~40fps from 30kft) and got advised by more experienced folks there to use a a bit smaller chute next time. This wasn't planned on my part. The rocket used a Chute Release, but the chute already unfurled near apogee.

Reinhard
 
If you look at the high altitude forecasts, you can see that the winds up there are often significantly above 15 mph, especially if you hit the jet stream. You will probably still stay within BR15, but recovery can turn into a little adventure, if the rocket lands further away. Much of that area out there is not a flat playa.

For what it's worth, I once stayed about 13min in the air at BALLS (descending ~40fps from 30kft) and got advised by more experienced folks there to use a a bit smaller chute next time. This wasn't planned on my part. The rocket used a Chute Release, but the chute already unfurled near apogee.

Reinhard

That’s a fair point. My “worst case” was an average, and assumes low winds closer to the surface. I can go down to a 24” parachute and still have a safe decent rate. I just don’t want to go to dual deploy if I don’t have to. I had a bad experience with cable cutters recently and I want to avoid using them until I have more experience using them.
 
Spent the last few hours since getting home from work today reconfiguring my av-bay to fit an 808 keychain camera. Had to dissect it and epoxy the lens to a cut up section of tubing to hold it in place properly. Never thought I’d get onboard video on a rocket this small, but here we are…

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I understand that, my issue is that I don’t have a 54/4000 case (as much as I want one), and I’d probably be busting the Tripoli Phoenix waiver if I tried it there

You will not break the waiver on the Loki. Nor will you set the L record with anything less than the Loki L-2050, just from a simple Newton-second standpoint. I only mention this because I'm actively trying to encourage people to break the current L record. For motivation purposes 😁

What sims are you using to get your altitudes predictions?
 
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You will not break the waiver on the Loki. Nor will you set the L record with anything less than the Loki L-2050, just from a simple Newton-second standpoint. I'm actively trying to encourage people to break the current L record. For motivation purposes 😁

What sims are you using to get your altitudes predictions?

RasAero says I’m at 45k on the K300, and 47k on the L265. Which I’m certain is optimistic. But if I break 35k on the K300, I’m fairly certain I can crack 37k on the L265 ;)
 
I think you are greatly underestimating the average wind speed at altitude. In the 10 times I’ve been to BALLS I’d say the winds aloft on average were far greater than 15 mph. A couple years ago we had a rocket that went to 50K’ feet drift at 50-60 FPS while descending at about 60-70fps. It landed over 7 miles away. Looking at winds aloft right now they are in the 30mph range starting at 6400’ and at 18k’ in the 40mph range.

A ballpark calculation shows a drift distance of 10 miles with an average wind speed of 30 Mph (44fps) and a 25fps descent rate from 30k’. (Very likely over the mountains to the northeast. Not an easy recovery.) I’ve flown a number of 54mm MD rockets on the CTI 6XL case (mostly the L265 and the L935) at BALLS and even with dual deployment and no drogue I still experience a fair amount of drift.


Tony
 
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I sure hope that TRA does NOT recognize flights that leave the waiver as a viable record breaker.
Nothing against the OP or this flight - cool rocket, wish you luck, thanks for sharing the build - but busting the waiver is ALWAYS a bad thing.
 
I sure hope that TRA does NOT recognize flights that leave the waiver as a viable record breaker.
Nothing against the OP or this flight - cool rocket, wish you luck, thanks for sharing the build - but busting the waiver is ALWAYS a bad thing.

If out of waiver, no record.

"1.1 Safety is of primary importance. TRA and Prefects and TAP members request that launch competitors, competitor’s assistants, RSO’s and LCO’s take all precautions to prevent any accident or injury to TRA members, launch spectators, and other competitors. The TRA safety code must be followed as applicable. This includes landing within the waiver cylinder."
 
I sure hope that TRA does NOT recognize flights that leave the waiver as a viable record breaker.
Nothing against the OP or this flight - cool rocket, wish you luck, thanks for sharing the build - but busting the waiver is ALWAYS a bad thing.
I think that TRA "records" have just become "high flights" as there are records that don't conform to the rules. Too bad IMO.

The most difficult part of setting K/L records is that the rocket is slowing down within the jet stream. If there is a significant jet stream, which is often the case, the flight gets sawed off. My advice in that case is to save the motor for another day.

Jim
 
I sure hope that TRA does NOT recognize flights that leave the waiver as a viable record breaker.
Nothing against the OP or this flight - cool rocket, wish you luck, thanks for sharing the build - but busting the waiver is ALWAYS a bad thing.

I don’t plan on leaving the waiver, and I’ll be monitoring the winds aloft determine the best time to fly. I’ve already decreased the parachute size, and while I’d rather not, I still can add a cable cutter before I fly.
 
Arrived on the lakebed on Friday morning. I wanted to be as prepped to fly as possible on Thursday night, but we arrived at Bruno’s around 10pm and just wanted to sleep.

Friday morning was by far the best time to fly for a record attempt. No wind and high altitude winds were low. Unfortunately I missed the 9am lowering of the waiver by a few minutes. 6pm was the next time the waiver was going to be bumped up for anything flying up to 60k. Winds were a little more than I would’ve liked, so I decided to hold.

Saturday was extreme winds all day, and Sunday was also no good to fly. So unfortunately I’m going home with no flight attempt. Going to try again with Tripoli Phoenix when I get a chance.
 
Yeah I want this to be as perfect a flight as possible. But this give me time to take it back into the workshop for some changes, such as adding a drogue and cable cutter. Also thinking about swapping the Raven for a different flight computer, but I’m not sure about that yet.
 
Yeah I want this to be as perfect a flight as possible. But this give me time to take it back into the workshop for some changes, such as adding a drogue and cable cutter. Also thinking about swapping the Raven for a different flight computer, but I’m not sure about that yet.
Since you're just looking for a basic dual deploy altimeter, you could just use an Eggtimer Quark or Missileworks RRC2+ (or equivalent Featherweight product if they have one). Very basic, but small and light.
 
Since you're just looking for a basic dual deploy altimeter, you could just use an Eggtimer Quark or Missileworks RRC2+ (or equivalent Featherweight product if they have one). Very basic, but small and light.

I was planning on using my easy mini. All it needs to do is deploy, and I know they’re Mach immune as I’ve flown them past Mach with no issues before. MissileWorks RRC2L was my second choice.
 
I’ve also decided that I’m not going to include the camera for a future flight attempt. With the way it’s setup, there’s no way to turn on the camera at the pad and has to be done during prep. The battery for the camera is so small that it only lasts for about 20 minutes and by the time I get everything ready, the battery is already dead. So unless I can figure out a way to arm it from the outside, it’s just added mass.
 
That’s a fair point. My “worst case” was an average, and assumes low winds closer to the surface. I can go down to a 24” parachute and still have a safe decent rate. I just don’t want to go to dual deploy if I don’t have to. I had a bad experience with cable cutters recently and I want to avoid using them until I have more experience using them.
No joke about upper altitude wind speeds. Download the Windy app on your phone. It will give you a much better idea of how much drift you will get. For example, right now my surface winds are 15mph and also 15mph at 35,000' But, 100 miles west the winds at 35,000' are close to 70 mph. You open a main at that altitude and that wind speed and your bird will be 30-40 miles away by the time it lands.

Use a chute release on the main and a small drogue that brings it down at about 40-50 mph. I know it's for an altitude record, but it won't add much weight, especially if you use thin mil chutes, and will make recovery much less challenging. You can always ditch the chute release and drogue on a future flight for more altitude, but I doubt it would make much difference either way. You can sim it to determine the relative difference.
 
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