Hello!! New member to the forum. Getting back into rocketry after a long hiatus with a Level 1 Cert Attempt.
My goal date is a certification attempt on December 19th (contingent on weather, building, etc.) , with a 1G 54mm CTI I218.
I chose to build a MAC Performance 4" Blackfly, with the following component specs:
4 days after ordering, and speaking with Mike (great customer service btw! has been very helpful in guiding on this kit), I received this package:
Dry fitting the parts, the build quality of this kit is clear. The tolerances are very tight, and the canvas airframe is fantastic. My how things have changed in a decade. The cat took interest, too.
Started with assembly of the motor mount and recovery harness attachment point, along with the avionics bay. I am going to pause the avionics bay assembly at this point until I finish building the Eggfinder Tx, and fit an antenna that will protrude slightly through the top bulkhead into the nosecone. I am going to draw up a sled that bolts into the threaded cap of the avionics bay to hold a LiPo battery and the Eggfinder board.
I've calculated the inside volume of the wildman nosecone by approximating the avionics as a cylinder, and the portion of the nosecone after the bay as a cone, and subtracting the volume of the tip. With that volume (~145 in^3), I calculate that I need 3x 3/16" vent holes, using the relationship: Vent Area = ((Volume) / 100 in^3) * .05 = .073 in^2.
Open question, I'd love some input on this if anyone has thoughts. Assuming that I want the vent holes for the barometer on the Eggfinder as far away from the curve of the nose cone, and along the straight edge of the airframe's cylinder shape, so that I minimize airflow disturbances and am sampling from a smooth laminar airflow, I am thinking I will place these three 3/16" holes about 2" below the nosecone, in the airframe and through the coupler.
Obviously, they will need to line up for flight, but that won't be a problem because I am going to use a single shear pin. I can place the 3 vent holes and the threaded shear pin hole so everything lines up nicely.
Again, I am not using the flight computer for any barometric triggered recover events on this flight. I would like barometric data as clean as possible though, just to nerd out on afterwards.
Thoughts or input on hole placement? Is my above thinking reasonable?
One consideration, I may bolt two ejection charge canisters on the bottom CR of the avionics bay, if there is room. I haven't thought this through or made any measurements to see if it is even possible, but I'd love to have future electronic deployment capability for some high altitude flights and let this thing rip on a K or an L motor. I've already done a Rocksim of the largest L that CTI makes I could fit in this thing, and CG checks out and the rocket is still stable, thanks to the Wildman nosecone and the mass of the avionics. What (if any) are the general best practices for mounting deployment canisters on the bottom of a nosecone?
Rail buttons were a snap to mount. I used an Al angle iron to get a straight line along the chord of the airframe. Then crafted two, 1" x 1" x .25" Pine wood blocks, and Dremel tooled a curve that matches the ID of the airframe, than drilled out holes for two Tee nuts. . I was careful to keep epoxy out of the threads. This ended up turning out perfectly, and I now have removeable rail buttons.
My goal date is a certification attempt on December 19th (contingent on weather, building, etc.) , with a 1G 54mm CTI I218.
I chose to build a MAC Performance 4" Blackfly, with the following component specs:
- Wildman 4" 6:1 Nosecone
- 7" x 54mm avionics bay in Nosecone
- Eggtimer TRS GPS Tracker/Flight Computer, 900MHz (No electronic deploy, just curious on collecting flight dynamic data, and using for locating)
- Eggfinder LCD Rx w/ LCD-GPS and Bluetooth
- 54mm MMT, with 2G CTI 54MM kit and spacer
- JollyLogic Chute Release
- 4ft Rocketman parachute, am thinking of switching this out for a 5ft, considering I am using a JLCR
- Aero Pack Retainer
4 days after ordering, and speaking with Mike (great customer service btw! has been very helpful in guiding on this kit), I received this package:
Dry fitting the parts, the build quality of this kit is clear. The tolerances are very tight, and the canvas airframe is fantastic. My how things have changed in a decade. The cat took interest, too.
Started with assembly of the motor mount and recovery harness attachment point, along with the avionics bay. I am going to pause the avionics bay assembly at this point until I finish building the Eggfinder Tx, and fit an antenna that will protrude slightly through the top bulkhead into the nosecone. I am going to draw up a sled that bolts into the threaded cap of the avionics bay to hold a LiPo battery and the Eggfinder board.
I've calculated the inside volume of the wildman nosecone by approximating the avionics as a cylinder, and the portion of the nosecone after the bay as a cone, and subtracting the volume of the tip. With that volume (~145 in^3), I calculate that I need 3x 3/16" vent holes, using the relationship: Vent Area = ((Volume) / 100 in^3) * .05 = .073 in^2.
Open question, I'd love some input on this if anyone has thoughts. Assuming that I want the vent holes for the barometer on the Eggfinder as far away from the curve of the nose cone, and along the straight edge of the airframe's cylinder shape, so that I minimize airflow disturbances and am sampling from a smooth laminar airflow, I am thinking I will place these three 3/16" holes about 2" below the nosecone, in the airframe and through the coupler.
Obviously, they will need to line up for flight, but that won't be a problem because I am going to use a single shear pin. I can place the 3 vent holes and the threaded shear pin hole so everything lines up nicely.
Again, I am not using the flight computer for any barometric triggered recover events on this flight. I would like barometric data as clean as possible though, just to nerd out on afterwards.
Thoughts or input on hole placement? Is my above thinking reasonable?
One consideration, I may bolt two ejection charge canisters on the bottom CR of the avionics bay, if there is room. I haven't thought this through or made any measurements to see if it is even possible, but I'd love to have future electronic deployment capability for some high altitude flights and let this thing rip on a K or an L motor. I've already done a Rocksim of the largest L that CTI makes I could fit in this thing, and CG checks out and the rocket is still stable, thanks to the Wildman nosecone and the mass of the avionics. What (if any) are the general best practices for mounting deployment canisters on the bottom of a nosecone?
Rail buttons were a snap to mount. I used an Al angle iron to get a straight line along the chord of the airframe. Then crafted two, 1" x 1" x .25" Pine wood blocks, and Dremel tooled a curve that matches the ID of the airframe, than drilled out holes for two Tee nuts. . I was careful to keep epoxy out of the threads. This ended up turning out perfectly, and I now have removeable rail buttons.
