PM Black Brandt X L2 Cert Questions

I've been preparing for my L2 cert. I have already passed the written Tripoli test, and was planning on flying an EZI-65 on a J90. However, I have recently been given and built a Public Missiles Black Brandt X. I'd much rather get my L2 cert on it, as it is a nicer rocket. However, I have a few questions:

1. On the motor I chose (J460T), the rocket motor chart says it will go to approximately 3700 feet. As such, I was planning on flying it drogue-less with a chute release. Do you guys think this is safe? Am I just being a wuss and should instead fly it with basic motor ejection at apogee? I've done drogue-less dual deploy with the release before, but never with such a heavy rocket.

2. The public missiles website says the optimum delay is 12.5 seconds. However, my own sims say it is closer to 13.1. As such, I was planning on just leaving the motor at the factory standard 14 seconds. I have a 54mm delay driller, but I usually prefer for it to eject a little after apogee rather than before when it is still going up. I've had some bad experiences with the delays running a bit faster than they should. Also, by not drilling it out, that's one less thing that could go wrong. Do you think this is the right choice?

3. I purchased a J90 reload from Bay Area Rocketry for the EZI attempt, but that would be under-powered for the Brandt. Has anyone ever asked if they can swap a motor out for the same type, but of a higher thrust? Both the J90 and J460 are for the same case and are listed at the same price. I was going to shoot the owner an email, but thought I thought I'd ask you guys first. Also, before you tell me that they require different closures, I know and have a standard enclosure too. Also, I left the kwik-switch or whatever you call it part off the 54mm tube, so the motor will fit.

4. Finally, a style question. I've never worked with quantum tube before, so I was wondering if its true that it doesn't need to be primed. I am just planning on spraying it with the standard Rustoleom stuff from home depot.

Thank you for your time.

Edit: Nevermind. Originally read your post as "I was given a built PML Black Brandt X."

1. On the motor I chose (J460T), the rocket motor chart says it will go to approximately 3700 feet. As such, I was planning on flying it drogue-less with a chute release. Do you guys think this is safe? Am I just being a wuss and should instead fly it with basic motor ejection at apogee? I've done drogue-less dual deploy with the release before, but never with such a heavy rocket.

I'm not sure I understand? Are you flying dual recovery with a flight computer or single deploy? JLCR enables a dual recovery type recovery with a single ejection charge. Saying drogueless implies more than one ejection event. Either way, the simpler the better for an L2 would be my recomendation. I would say with all those options at your disposal, run motor eject with a chute release on a main chute. If you want, you could run a flight computer with dual ejection, but leave the motor eject in for redundancy.

2. The public missiles website says the optimum delay is 12.5 seconds. However, my own sims say it is closer to 13.1. As such, I was planning on just leaving the motor at the factory standard 14 seconds. I have a 54mm delay driller, but I usually prefer for it to eject a little after apogee rather than before when it is still going up. I've had some bad experiences with the delays running a bit faster than they should. Also, by not drilling it out, that's one less thing that could go wrong. Do you think this is the right choice?

I agree with this, but I think drilling a little would be fine too. Motor eject times can vary by a second or two anyway. Always go with your own sims (you know your actual built pad weight, the mfg does not).

3. I purchased a J90 reload from Bay Area Rocketry for the EZI attempt, but that would be under-powered for the Brandt. Has anyone ever asked if they can swap a motor out for the same type, but of a higher thrust? Both the J90 and J460 are for the same case and are listed at the same price. I was going to shoot the owner an email, but thought I thought I'd ask you guys first. Also, before you tell me that they require different closures, I know and have a standard enclosure too. Also, I left the kwik-switch or whatever you call it part off the 54mm tube, so the motor will fit.

Yeah, you are just gonna have to contact Mike at BAR. I don't know if he does this or not. If he doesn't but you don't want to shell out for another, you could ask your local club if someone would trade you.

4. Finally, a style question. I've never worked with quantum tube before, so I was wondering if its true that it doesn't need to be primed. I am just planning on spraying it with the standard Rustoleom stuff from home depot.

I sand mine then do two coats of Rustoleum, no primer. Seems to hold up fine, but I'm far from a perfectionist.

On my heavier rockets using motor ejection and chute release, I also have a drogue chute attached to the shock cord.

Flyfalcons said:

On my heavier rockets using motor ejection and chute release, I also have a drogue chute attached to the shock cord.

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I was wondering how you would do that. Where do you attach the main and the drogue? How long of a line do you use?

Rocket501 said:

I was wondering how you would do that. Where do you attach the main and the drogue? How long of a line do you use?

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Good questions to ask while preparing for L2.

If I set it up, I'd have the main 1/3 along the shock cord closer to the bigger/heavier piece of rocket. tie on the drogue far enough away form the main so it doesn't risk tangle or fouling.

Shock cord length is somewhat of a religious debate. There's the 5x rocket length camp, the twice height of tallest tree crowd, the 3x length of longest piece it's attached to crowd, and that isn't even dealing with nylon vs kevlar

Rocket501 said:

I was wondering how you would do that. Where do you attach the main and the drogue? How long of a line do you use?

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I put the drogue about 1/3 of the shock cord length down from the nose cone so the parts don't hit each other during descent, and I keep the main pretty close to the nose cone (assuming the nose isn't hollow, if it is then I like to leave lots of shock cord between the parachute and nose).

Thank you for letting me know. It's a bit embarrassing, but I made a mistake in assembling the kit. Basically, there is a short strap that is supposed to have one end connected to the motor mount and the other to the piston. The main parachute cable then connects to the piston. However, I mistakenly (I'm used to assembling rockets like this) connected the main line directly to the motor mount. If I omit the piston, will the ejection charge still have enough force to push the chute out? I really think it should be fine. I'm not concerned about the temperature, as I have a nomex chute protector that will fit, but if it isn't needed, why was the piston even included?

Pistons work with Less BP than normal. Use a BP calculator (rockethead's ejection calculator is good, google)

Its PML's novelty feature. Some folks ditch them immediately, others turn them upside down, many ways to skin the cat.

A sticky point with pistons is they may stick in cold weather so fit checks are necessary u fil they e been sanded to shape (quantum tube contracts more than other materials)

My $0.02
I did my L2 cert with a big fat 5.5" Nike Smoke that weighed just over 9 lbs fully loaded with a J430. You asked about safety with a drogue-less decent: my cert flight was specifically a motor (only) ejection with JL chute release, so most of the decent was 'drogue-less'. The RSO overseeing my flight did not object to this, and my de facto mentor who is president of our club had recommended that I do this kind of recovery for my cert flight with that rocket.
Slow and low for cert flights--and simple.