HyperLOC 835 flight 1.9

Hi folks, sitting here thinking about every possible outcome for my pre-cert flight this weekend (hence 1.9... aren't I the clever one? ) I didn't do a build thread, but I can at least give you some basics. I built this rocket stock except for using 3/16" ply for the fins in place of the provided - and highly warped - 1/8" ply. Wood glue for everything except external fillets - did those with Rocketpoxy because I'm less of a nudnik making fillets with this medium. RRC2+ altimeter.

Below is the list of things I am still sorting out.

1. Seems like I should drill vent holes in the booster between each mmt cr (of which there are three). I've heard of airframe blowouts due to overpressurization (albeit rare).
2. Still need to confirm my bp charge sizes. I'm using the rubber glove method. That sounds weird.
3. I'm using the supplied nylon harnesses, though they seem a bit short for my liking. 12' and 18', I think.
4. Using supplied main (48") and drogue (18"), with nomex and some dog barf.
5. The plan is to use steel screws to attach av bay to the payload. Friction fit the nose cone with one vent hole in payload bay. Deploy drogue from payload at apogee, God willing.
6. 3x 2-56 shear pins in booster to av-bay point. Deploy main at 500'.
7. Motor is a CTI I195 RL with a 38/54 adaptor. Aeropack retainer. Projected 1800'. I will need to take the ejection charge bp out of the motor.

Anything on that list jump out as particularly concerning? I get there are different ways to do things - so I'm really looking to hear if anyone is worried that a certain decision is likely to fail.

Is this a L1 or L2 cert flight?

Looks good to me. I built mine completely stock including the fins. The harness length seemed fine. I used 3 shear pins at separation points immediately on either side of the AV bay, then fastened the payload air frame to the nosecone with self tapping screws. I know that was unconventional, but no one at the launch could think of an actual argument against it.

Here is my ejection test with 1.8 grams. 1.5 probably would have sufficed.

[video=youtube;nMNDSLDVoxs]https://www.youtube.com/watch?v=nMNDSLDVoxs[/video]

All of that being said, I forgot the bolt the main side bulkhead onto the AV bay (installed, just no nuts holding it on), so my whole air frame separated in the middle at apogee and the booster section came in ballistic.

Looks like you've thought of all the important stuff. Don't forget the little things come launch day

BC

Me? I would main deply 800-1000' Just because I like to give the main more time to inflate. Depends on a lot of things though such as you packing method, the winds etc etc.

noffie79 said:

Is this a L1 or L2 cert flight?

Click to expand...

The rocket will eventually be used for a L2 cert flight. Flight 1.9 is more or less a shakedown flight in preparation for that. I already have my L1.

Thanks for sharing the video Brian. Cripes that thing came out hot! I love that color scheme. Good call on the little things, I'm a list-maker and checker-offer for endeavors such as this.

Thanks! Here is a still photo. The text is a custom vinyl from StickerShock23 in chrome =)



And yes, came out very hot. I only had time for the one test fire that day so I don't think I used much less for the flight, but I will probably do more testing after the rebuild and slowly step down to get a good (but reasonable) ejection.

Another question you had was vent holes. I think I just put 2 in the booster and 2 in the payload, both just in the middle somewhere. I did not specifically put any in between the CRs. I'm not sure how quickly you would have to be going and how high you would have to get to blowout that volume of cardboard air frame. I imagine the answers are "very fast" and "very high", which I never planned to do with my Hyperloc. I think I sim'd the AT J350 to 3600' at a top speed of ~450mph.

BC

To wrap up this thread, I flew the HyperLOC this weekend. I did make some changes to the stated plan above:
1. drogue was in the booster; separated at apogee
2. main was in payload; deploy at 800'
3. it was a bit too windy for my liking, so I added a JL Chute Release to the main set to 400'. I did this because I was too lazy to unpack the rocket and change the altimeter main deploy settings. Also, possibly invented triple deploy with that setup.
4. friction fit everything; shear pin testing was not going well

Everything went great in terms of the flight (1692' by the RRC2+) and drogue/main/chute release events. I still managed to catch a bit of a breeze so I got to experience swamp rocket recovery. The rocket was only ~25 feet into the woodline so it wasn't too arduous a recovery task. Everything was recovered without damage.

Thanks for the help with brainstorming through the last minute details. Time for paint - I think I have a theme for the rocket based on my time in the swamp.

Hey Brian, does that picture show your rocket supported by your launch pad without the legs on it? I am real curious about the bracket you used to attach the 1010 rail to the base.

Yeah, it has legs, they just weren't on. I will take a close up of the stand tonight and post it. I basically put 4 "L" brackets going around the bottom of the rail then U bolted it to the PVC cross piece.

I don't have a plate of any kind on it yet, so at this point, it's just a stand. Its also only 4 feet of rail, so I'm not sure I would ever use it to launch. Maybe for MPR...

BC

Hey Matt

How many band-aids did you need?

H_Rocket said:

Hey Matt

How many band-aids did you need?

Click to expand...

Heh, yea. Decisions were made.

Sorry this took me a few days the remember. Here are upper and lower angle views of the bottom of my stand.





It is a 4 foot length of T-Slot Framing, 47065T101, and 4 brackets, 47065T239 . The PVC and U-Bolts are from Home Depot. It's 1" ID PVC, I think the U-Bolts are 1.5"?

All said and done I think it was about $40.