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.
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 developed a spreadsheet that takes the data from the Windy app and crudely provides a drift profile.
I haven't tested against real flights, but it would at least give you an idea of the drift possibly.
GPS Drift Predictor
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’ll definitely be using that in the future, thanks for sharing!
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.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.
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.
Let me know when you are going to fly Tom, my students are still asking me if you did it!?
That is a sexy beast!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”
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.And here’s the finished rocket put together for its final assembly before heading to Black Rock in a couple days.
View attachment 481784
I would be happy beating the K record by an inch! Even the current holder does not think he could.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’.
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!Amazing that grain stayed within the tower after the CATO. Sorry to see that result for you!
Haha almost. Has a huge dent in it from when it shot down the tower and into the rear closure.The fuel grain looks good. Send it.
Yeah offset core, or more specifically a C-slot.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.
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