Perfect flights

[SCOTT EVANS]

Perfect flights hi alt 45 mach delay is a maximum of 12 seconds.
At 12 seconds the rocket has slowed to .8 according to the sim.
Is that enough?

[AdrianParticipant]

That should be just enough if your sim is accurate. Are you using Rocksim, and what kind of nosecone in the sim and on your rocket? If Rocksim is over-predicting your drag your rocket could be at risk of a Mach-induced early deployment with the 12 second delay. Also, if your rocket has a bad problem on liftoff and it’s on the ground 12 seconds after launch detect, that would be a fire hazard.

[edwardModerator]

I’d sim it in RasAero – it has been spot on for all my high performance flights. I’ve compared data predicted to data from the flight and through 3 flights I’ve never had variances of more than 2%. I waited until my rocket came down below 500 mph before I pulled the mach delay off. On the units I was using I set it for 34 seconds.

I don’t think the situation of having a liftoff problem and setting a long mach delay should govern your settings. I’d be more worried about having a rocket shred at high altitude and spreading confetti over a wide area than a liftoff issue.

Edward

[John A. WilkeParticipant]

Scott, there is a 24 second mach delay…. Go to http://www.perfectflite.com/Downloads/HA45Kman.pdf and scroll down to page 8 of the manual (which is page 11 of the downloaded .pdf) You lay the jumper horizontally across J3 and J4 on the pins closest to you.

In a very related note, I was the very first person to fly this altimeter – I did the beta testing. My comment only comment was an emphatic 12 SECONDS OF MACH DELAY IS NOT ENOUGH!!!!!!!!!! (quote 8) ) and Peter did a workaround and came up with 24 seconds by laying the jumper sideways. He was shocked 12 seconds wasn’t sufficient, but he fixed it.

When flying the Ratt M, which burns for 13 seconds, you very much need more than 12 seconds.

[SCOTT EVANS]

Scott, there is a 24 second mach delay…. Go to http://www.perfectflite.com/Downloads/HA45Kman.pdf and scroll down to page 8 of the manual (which is page 11 of the downloaded .pdf) You lay the jumper horizontally across J3 and J4 on the pins closest to you.

In a very related note, I was the very first person to fly this altimeter – I did the beta testing. My comment only comment was an emphatic 12 SECONDS OF MACH DELAY IS NOT ENOUGH!!!!!!!!!! (quote 8) ) and Peter did a workaround and came up with 24 seconds by laying the jumper sideways. He was shocked 12 seconds wasn’t sufficient, but he fixed it.

When flying the Ratt M, which burns for 13 seconds, you very much need more than 12 seconds.

Oh thank you thank you.
I was wondering if you would chime in. 😉

[John A. WilkeParticipant]

No worries. The PerfectFlite guy (Peter) printed his circuit boards before he got my comments… that is why the boards don’t show the 24 seconds but the manual does.

That is a is a decent little altimeter if you aren’t wanting to capture a bunch of data. I wish they’d take smaller batteries for small rockets, though – I just bought a Raven that I’m looking forward to flying as well!

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