Attempting the K and L altitude records

The Rocketry Forum

Help Support The Rocketry Forum:

watheyak

Barnstormer
TRF Supporter
Joined
May 11, 2009
Messages
1,064
Reaction score
864
Location
Arizona
Why not a Raven? It has a proven track record on flight like this. Especially in cases where the static Port is pointed I to the relative wind such as on a nosecone. Not sure if yours is like that, but mine always are.
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
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.
I did use the windy app to help out. Upper level winds on Friday morning were only around 30mph IIRC. But just below that the winds were going in the complete opposite direction. Either way the rocket didn’t fly and dual deploy is going to be added for TRAPHX flights.
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
Why not a Raven? It has a proven track record on flight like this. Especially in cases where the static Port is pointed I to the relative wind such as on a nosecone. Not sure if yours is like that, but mine always are.
I like the Raven for the capabilities they provide in such a small package. But losing them over and over gets expensive. Just this year I’ve toasted four of them in various ways.
 

dvdsnyd

Well-Known Member
Joined
May 9, 2012
Messages
297
Reaction score
108
I’ll definitely be using that in the future, thanks for sharing!
No problem, I'd be really interested to see how well it works for you. Let me know if you have any questions or problems with it.
 

wsume99

Well-Known Member
Joined
Feb 28, 2014
Messages
253
Reaction score
69
Random thought as I was following the discussion ... how does the descent rate change with altitude? I've never noticed a significant difference in descent rate on my flights but they are all under 5k feet. If you are going up to 30k feet I'm assuming the density reduction will have some effect. Does anyone have data from actual flights to shed some light here? Unless the main opened at apogee I doubt there will be many that do.
 

Mike Haberer

DaHabes
TRF Lifetime Supporter
TRF Supporter
Joined
Jan 7, 2019
Messages
911
Reaction score
655
Random thought as I was following the discussion ... how does the descent rate change with altitude? I've never noticed a significant difference in descent rate on my flights but they are all under 5k feet. If you are going up to 30k feet I'm assuming the density reduction will have some effect. Does anyone have data from actual flights to shed some light here? Unless the main opened at apogee I doubt there will be many that do.
Descent will be faster at higher altitudes but will slow down as you drop. You can sim it in OR or Rocksim by setting your launch altitude to 30,000' and see what your landing speed is for the chute you are using, then compare that rate to the landing speed at your ground level sim.
 

Buckeye

Well-Known Member
TRF Supporter
Joined
Sep 6, 2009
Messages
2,863
Reaction score
639
After you sim it in OR or RS, plot velocity vs. altitude to see the relationship.
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
Revised the Av-bay tonight. Easy Mini and Featherweight GPS now live in the av-bay. Next up is a hot wire cutter for dual deploy.
 

Attachments

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
Hot wire cutter. Nicrome wire wrapped around a beaded cable tie. When the easy mini “fires” the main charge, it heats the nicrome wire long enough to melt the cable tie that’s holding the parachute closed. Basically a cheap, compact, and lightweight version of a cable cutter.
 

Attachments

Buckeye

Well-Known Member
TRF Supporter
Joined
Sep 6, 2009
Messages
2,863
Reaction score
639
How long is the current flowing to the nichrome wire? Is this latch time (is that the correct term?) adjustable in the easy mini?

Does the chute get a little burned/melted also?
 

dvdsnyd

Well-Known Member
Joined
May 9, 2012
Messages
297
Reaction score
108
Along the same lines as Buckeye, my question - have you tested your cable cutter configuration?
May also not be a bad idea to test it right in front of a box fan set on high. You'll have some wind potentially impacting the heating of your nichrome wire.
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
How long is the current flowing to the nichrome wire? Is this latch time (is that the correct term?) adjustable in the easy mini?

Does the chute get a little burned/melted also?
Along the same lines as Buckeye, my question - have you tested your cable cutter configuration?
May also not be a bad idea to test it right in front of a box fan set on high. You'll have some wind potentially impacting the heating of your nichrome wire.
I still need to test it with the easy mini just to be sure, but previous testing has shown me that it tends to work within a half second.

I’ll have something in between the parachute and nicrome for the actual flight, maybe a piece of tape on the parachute, stuck there before folding and adjusted so it’s against the nicrome.

The box fan test idea isn’t terrible, I’ll see if I can get something like that together, but this is a proven method of deployment I’ve used before.
 

dvdsnyd

Well-Known Member
Joined
May 9, 2012
Messages
297
Reaction score
108
I still need to test it with the easy mini just to be sure, but previous testing has shown me that it tends to work within a half second.

I’ll have something in between the parachute and nicrome for the actual flight, maybe a piece of tape on the parachute, stuck there before folding and adjusted so it’s against the nicrome.

The box fan test idea isn’t terrible, I’ll see if I can get something like that together, but this is a proven method of deployment I’ve used before.
Good to hear!
I thought too afterwards, that it looks like you wrap your nomex around the parachute after the zip tie/nichrome cutter. If that's the case, the nichrome won't be as exposed to the wind.

In my experience with cable cutters. Commercially available by Prairie Twister and my own 3d printed variants. I burrito wrap the heck out of the chute and attach the zip tie/cutter combo over that.

Either way, looks like you are well on your way! :) Hoping for your success!
 

JackC

Well-Known Member
Joined
May 2, 2020
Messages
75
Reaction score
42
And here’s the finished rocket put together for its final assembly before heading to Black Rock in a couple days.
View attachment 481784

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”
That is a sexy beast!
 

plugger

Well-Known Member
Joined
May 1, 2009
Messages
589
Reaction score
269
And here’s the finished rocket put together for its final assembly before heading to Black Rock in a couple days.
View attachment 481784
Looking at that pic, I can't help but think your apogee is going to be significantly less than your sims. I know I'm making assumptions, but given your rough apogee estimates I expect you have the finish set to 'polished' in OpenRocket. Looking at the picture above, specifically the fin can, I can see imperfections that will definitely induce drag.
1634804131671.png

The best way to get rid of that is to wipe epoxy over it, sand it back; wash-rinse-repeat until you have a uniform flat surface. The other thing I'd say is that you're running the risk of popping a fin on landing given your swept back profile fillet only fin attachment.
 

6inchmonster

Well-Known Member
Joined
Oct 20, 2021
Messages
126
Reaction score
49
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.
View attachment 481669
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’.
I would be happy beating the K record by an inch! Even the current holder does not think he could.

That said, good luck and go for it.
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
So good news, unlike at XPRS, the winds were calm enough that I could fly and so I got everything set up and ready to go for the waiver opening on Sunday morning.

The motor spit two igniters before the third attempt actually got it lit. That however is where the good news ends. Just as the motor came up to pressure, it blew the rear closure and nozzle out. The motor case and airframe went about 100’ up according to the easy mini. Luckily the airframe and electronics appear to be unscathed, and once I have a new motor case and reload, I’ll be making another go at this.

I had a GoPro camera shooting at 240fps near the tower that caught the whole event:

597FA542-A721-4DB5-B18F-4EA5B2313388.jpeg

C17C4959-8044-41D0-BACE-71481729DA17.jpeg
28A07DBF-B9DF-4B2E-B47D-90474F4563B2.jpeg
 

rfjustin

Well-Known Member
Joined
Jan 21, 2009
Messages
3,291
Reaction score
2,351
Location
Franklin, WI
Amazing that grain stayed within the tower after the CATO. Sorry to see that result for you! :(
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
Amazing that grain stayed within the tower after the CATO. Sorry to see that result for you! :(
Yeah it was kinda crazy that the grain and fin can stayed in the tower. I guess I can say I literally left the fins on the pad!

As unfortunate as it is, it’s basically just another delay as I’ve still yet to find any damage to anything other than the motor casing. That being said, even the motor case might still be good. It might just be the rear closure that’s no longer usable.
 

Wayco

Desert Rat Rocketeer
TRF Lifetime Supporter
Joined
Mar 23, 2011
Messages
3,751
Reaction score
851
Location
Goodyear, AZ
That's an offset core, right? I had a K300 do something like that when I didn't get the ignitor all the way up to the top of the grain.
Hope it wasn't the ignitor I gave you.
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
That's an offset core, right? I had a K300 do something like that when I didn't get the ignitor all the way up to the top of the grain.
Hope it wasn't the ignitor I gave you.
Yeah offset core, or more specifically a C-slot.

Robert DeHate seemed to think it was the igniter, but I’m not so sure after looking at the GoPro footage. The igniter totally burned up before the motor came up to pressure. It’s possible that it was just the rear closure that failed. I’m not sure to be honest.
 

CoyoteNumber2

Original San Diego High Power Rocketry
Joined
Jan 30, 2009
Messages
722
Reaction score
209
I've seen a lot of funny things happen with those -6GXL motors. Including a K300 pop on ignition just like yours.
 

ghostfather

Well-Known Member
TRF Supporter
Joined
Mar 28, 2018
Messages
267
Reaction score
215
Yeah, the K300 is hard to ignite, even with the supplied igniter having extra pyrogen. I've used an extra sliver of blue propellant taped to the igniter, worked every time.
 

ChristineZ

Member
TRF Supporter
Joined
Oct 7, 2021
Messages
17
Reaction score
53
Location
Acton, Massachusetts
I was thinking ignitor too....you may have had a little damage inside the narrow core slot after installing several of them??
 

T34zac

Well-Known Member
TRF Supporter
Joined
Jul 23, 2014
Messages
1,027
Reaction score
135
Location
Massachusetts
Going into the attempt, I knew that the chances of a cato happening were pretty high, considering the amount of Pro54 6XL catos in the last couple of years. And even two K300 catos at XPRS a month and a half ago. I’m just glad I’ll be able to make another attempt with minimal repair.

But as I said, I’m not convinced it was an igniter fault. I’m pretty sure it was just a rear closure failure. That tailcone and case I’ve had for years. That was the second firing of the case, but the first time I used the tailcone.
 
Top