There are a few other considerations that will help get you more performance.
The record rocket was a flying case style design, where there is no body tube. The nosecone with electronics and recovery system is mounted to the top of the motor, and a fin can is at the base. This helps reduce mass by a good amount. The fin can means you won't really manage to reduce frontal area that much, but there might be some minor aerodynamic benefits if you use a Bare Necessities style scalloped fin can.
I don't know the specifics, but the electronics and parachute must be packed very tightly into the limited volume of the nosecone, I suspect that it might have been flown with the parachute set to deploy at apogee to reduce volume.
The record flight was flown at Black Rock. Starting at about 4000 feet above sea level will help reduce drag a significant amount.
Finally I need to mention that there's a very good chance that the motor will fail on ignition. A friend of mine has tried to break the current K record with a rocket similar to the current record holder, and both times the motor has failed. I doubt he'll make a third attempt until he's sure that CTI has fixed the problem.
-Daniel F.
Apr 5, 2023, 7:00 AM by whitney@xxxxxxxxxxxx:
From my experience you will not get accurate altitude simulations from Open Rocket. Especially with flights in the transonic region. Open rocket is a great tool for design, weight and balance, CP to CG and general simulation. I have found that to get accurate altitude simulations for a particular rocket. You need to have a good idea as to what the actual coefficient of drag is. I have yet to find an easy way to adjust drag coefficients in open rocket. So I use RockSim and RAS Aero where you can easily adjust the drag coefficient to match the real world data.
Here is my process. After building the rocket. Enter all the actual weight and balance information to match the actual rocket into the simulation. Fly the rocket at least three times on different motors in the real world gathering barometric and accelerometer data from multiple flight controllers. Adjust drag coefficient to match the actual flight data achieved with the motors and conditions. Then you will get more accurate simulations of the actual rocket.
If you are not building an actual rocket and just living in the virtual world. Then I would play around with materials and surfaces in open rocket adjusting the drag to lower your over all coefficient of drag. I would create some unobtanium’s with really low drag numbers to trick Open Rocket into lower overall drag coefficients.
I hope this helps,
Whit
From: arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> On Behalf Of Raum
Sent: Wednesday, April 5, 2023 8:00 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: 10km (30k feet) with a K300
It goes at mach for 9 seconds, I tried to incorporate the boat tail and changed the fins a bit. Still got roughly 7500m, any recommendations? Thanks in advance.
On 4 Apr 2023, at 21:20, Ben Brockert <wikkit@xxxxxxxxx> wrote:
It’s a nose cone for supersonic flight, how much of the flight is supersonic? I don’t have the curves memorized, may be a silly question. If the 509 m/s is top speed a blunter nose might be better.
Can you fashion some quantity of boat tail? Often the winners of altitude competitions with a given kit at HPR meets I’ve been to are ones who had “engine retainer”s whose purpose were perhaps not purely engine retaining.
On Tuesday, April 4, 2023, Raum <Rocketry101@xxxxxxxxxxx> wrote:Hi guys,
After testing my motors for a while I am going to try 10km with a k (roughly 1400Ns, 600Ns average thrust). I saw a couple of records on the Tripoli website with K250 and K300 motors close and above 30k feet. The problem I have is that I can’t seem to get open rocket show me the magic number. Do you guys see any improvements I can make (I only wanted to reach the altitude that’s why I haven’t included the altimeters and parachutes)?<Screenshot 2023-04-04 at 21.07.46.png>
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