Level 3 Certification Rocket Selection

[Steinerino]

I have been thinking about my NAR level 3 certification. I have been enjoying minimum diameter rockets most recently. So my thought was to see if I could get a rocket to 30K feet. I have been looking at the Wildman Mach3 Carbon rocket as it sims in the mid to high 20K feet. That is the best I have seen so far.

That said, my question is about how people perform Head End Deployment with carbon fiber rockets with a tracker (I have been using Featherweights so far). There is no room for a nose cone tracker (fiberglass nose cone) and the body being carbon fiber will not work for radio transmission.

I have not yet thought about going after high power clusters or multiple stages. Trying to keep this a bit simpler at this stage.

Open to thoughts about kit selection as well as tracking.

Larry

 

[Titan II]

Attach the tracker to the shock cord. This is a common technique.

 

[Handeman]

In my experience, most sims tend to be optimistic on altitude. If you build it just right and use a Pro75-6GXL motor, you might tickle that 30K number. Of course clusters and staging is not allowed for cert flights so it would have to be a single motor.
BTW, per Thrust Curve sims, even a 3" minimum diameter on a Loki 54mm M1378LR in a 8 lbs. rocket will only top 20K.

Sounds like a very cool L3 cert flight. You will get the cert without hitting 30K, if you get the rocket back.

Good Luck

 

[Neutronium95]

That said, my question is about how people perform Head End Deployment with carbon fiber rockets with a tracker (I have been using Featherweights so far). There is no room for a nose cone tracker (fiberglass nose cone) and the body being carbon fiber will not work for radio transmission.

I was concerned about this on my BALLS project for this year. I mounted my Featherweight GPS at the top of my avbay, so the GPS antenna was inside the fiberglass nosecone shoulder and nosecone. I also reloacated the 900mhz telemetry antenna to the bulkhead, but I think that it would have been fine without being moved.



Also, it's my opinion that you don't really need carbon fiber. I used a carbon fiber tube mainly because I thought it looked awesome, not because I needed the strength. Good filament wound fiberglass tubes are very strong.

 

[Steinerino]

Attach the tracker to the shock cord. This is a common technique.

Attaching to the shock cord would then limit the transmission on the way up to apogee if I use a carbon fiber body tube in a head end deployment. I was hoping to get the real-time details on the way up.

 

[Steinerino]

I was concerned about this on my BALLS project for this year. I mounted my Featherweight GPS at the top of my avbay, so the GPS antenna was inside the fiberglass nosecone shoulder and nosecone. I also reloacated the 900mhz telemetry antenna to the bulkhead, but I think that it would have been fine without being moved.

View attachment 549429

Also, it's my opinion that you don't really need carbon fiber. I used a carbon fiber tube mainly because I thought it looked awesome, not because I needed the strength. Good filament wound fiberglass tubes are very strong.

This is a very clever installation! My only concern would be the 'room' available in the nosecone for the parachute. How did this project work out for you? Do you have pictures showing the lower half of the av bay installation to see the bottom half of the tracker? Very cool

 

[eggplant]

I'd recommend doing single separation dual deploy instead of traditional head end deploy as it both opens up the fiberglass nosecone for the tracker and can save length/mass. There are plenty of examples of how to implement it on this forum, but I'll throw in my 3" MD project as a sample too:

 

[Steinerino]

In my experience, most sims tend to be optimistic on altitude. If you build it just right and use a Pro75-6GXL motor, you might tickle that 30K number. Of course clusters and staging is not allowed for cert flights so it would have to be a single motor.
BTW, per Thrust Curve sims, even a 3" minimum diameter on a Loki 54mm M1378LR in a 8 lbs. rocket will only top 20K.

Sounds like a very cool L3 cert flight. You will get the cert without hitting 30K, if you get the rocket back.

Good Luck

I agree that sims tend to be optimistic. I will look up this

In my experience, most sims tend to be optimistic on altitude. If you build it just right and use a Pro75-6GXL motor, you might tickle that 30K number. Of course clusters and staging is not allowed for cert flights so it would have to be a single motor.
BTW, per Thrust Curve sims, even a 3" minimum diameter on a Loki 54mm M1378LR in a 8 lbs. rocket will only top 20K.

Sounds like a very cool L3 cert flight. You will get the cert without hitting 30K, if you get the rocket back.

Good Luck

I'd recommend doing single separation dual deploy instead of traditional head end deploy as it both opens up the fiberglass nosecone for the tracker and can save length/mass. There are plenty of examples of how to implement it on this forum, but I'll throw in my 3" MD project as a sample too:

Very cool build. How did you integrate the camera?

 

[DarthMuffin]

I doubt you could get a Mach 3 CF with any M motor to go under 20k! A small M simulates to 27k for my non-cf Mach 3. My Mach 2 CF went to 28.5k with an L935. Sim was to 31k and it probably would have if the leading edge fin tape didn't let go. I used an altus teleGPS with the antenna totally within the av-bay (and doubled back a little, no choice). I had signal all the way up and easily after deployment. The av bay is fiberglass so no issues with it blocking once you've popped the drogue.

As your L3 cert rocket, start looking for your l3cc member first. If it's like my tripoli experience, most won't want to work with you on a MD build unless you've had extensive MD experience at L2.

 

[OverTheTop]

Should be plenty of room in the NC for a tracker and altimeter. Here is an example from my 4" nosecone of my Velociraptor and Nike Apache. The sled itself is actually thinner so it can fit in a 75mm or even a 54mm NC.




More details here:
https://forum.ausrocketry.com/viewtopic.php?f=6&t=5019

 

[Buckeye]

BTW, per Thrust Curve sims, even a 3" minimum diameter on a Loki 54mm M1378LR in a 8 lbs. rocket will only top 20K.

Thrustcurve is great for quickly sorting through motors, but it is not a good simulation of altitude for rockets that fly fast, high, and for a long time. The default constant Cd of 0.6 is too large and altitude is underpredicted. You might do better with Cd set at 0.45 or 0.3. Better yet, use RASAero II for more precise predictions as it varies Cd with Mach Number.

Edit: Rocksim, even with variable drag, uses Cd that is too large. OpenRocket, not sure. Contrary to conventional wisdom, simulations often underpredict altitude for high performance flights.