Setting Mach delay - Northern Colorado Rocketry

This topic has 9 replies, 5 voices, and was last updated 17 years, 2 months ago by Adrian.

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July 17, 2008 at 12:25 am #40353
Bruce R. Schaefer
Okay… my next flight will be with a new rocket that has to have a shakedown flight before it earns its paint job. It’ll fly as the Gray
Ghost (primer) until it earns the metallic red of the Crimson Comet for an N boost. I’ll fly it at Oktoberfest. I’m using a MWC’s mini, and since it will hit a velocity of 878 mph, oh, I’d better set a Mach delay. Here are the flight stats: CTI L2375, 1.9 sec burn. 21 seconds to apogee. I’m thinking 8-10 seconds. Sound right?
July 17, 2008 at 1:27 am #48596
Jeffrey Joe Hinton
Moderator
I’d probably go with the 12 second set, won’t hurt it while in coast, doesn’t change anything otherwise. At least, that’s what i’d do if I were you.
July 17, 2008 at 1:54 am #48597
Anonymous
Most altimeter manufacturers suggest having mach delay employed until your velocity drops below 0.8 mach. For my M900 boosts in SkyScraper, I had the choice of 15 or 25 seconds. I had to go with the latter, as it was a motor that burned about 12 seconds and I was honkin’ right along at burnout. It was pretty scary for me the first time I set a mach delay at 25 seconds.

Obviously different manufacturers have different settings. I’d just make sure I was below mach 0.8 (ish) when the altimeters woke up.

I have a flight that will use 25 seconds this weekend 😯 It should be cool!

JW
July 17, 2008 at 2:46 am #48598
Doug Gerrard
Participant
JW, I still haven’t mastered the intricacies of programming the R2C mini even after viewing the video on Jim’s web site. I’m hoping he’ll do the programming for me on the site. All help will be accepted and appreciated, free entrance to the movies AND free popcorn 😉

Doug
July 17, 2008 at 2:50 am #48599
Anonymous
Doug, I know Jim will be there, he has a nice boost planned. I have not flown a MW “Mini” or I’d surely help you. For my shot, I’m using a tried-and-true HA45 from PerfectFlite.

Should be a great weekend!

J
July 17, 2008 at 2:54 am #48600
Doug Gerrard
Participant
I know Jim will be there

Yea, I have to deliver a couple of items to him. This really should be a good weekend. I’m already up here in CO. I came up a day early for business. But I’ll be out on Friday setting up my pad and equipment.

Doug
July 17, 2008 at 2:55 am #48601
Warren B. Musselman
Moderator
Don’t feel bad Doug, when I bought my pair of Mini’s, Jim walked through it with me twice and gave me this nice little reference card. I still can’t be sure I’ve programmed the thing right. I made an L1300 flight at MHM and had to get Jim to program the dang thing for me. Turns out it was a good thing – he’d flashed the firmware on the board and the reference card no longer was right in a couple key areas. I still have to get my second Mini flashed one of these days. Unless I’m sitting here in my shop with the reference in front of me and the video available, I still feel a bit awkward with the programming.

One of these days, maybe someone will make an altimeter that has a USB port on the thing so you can program it with a Palm or a laptop using a nice little graphical interface.

Warren
July 17, 2008 at 3:00 am #48602
Doug Gerrard
Participant
One of these days, maybe someone will make an altimeter that has a USB port on the thing so you can program it with a Palm or a laptop using a nice little graphical interface.

There is, the G-Wiz. (Sorry Jim). I use the HCX and the MC2 and, although its a pain in the butt to pull out the laptop, when i program it there is NO doubt I programmed it correctly. The software is VERY user friendly. I admit that the Missile Works capability of on the field programming without ANY additional hardware is appealing but I do NOT know that it is programmed correctly. (I’m just too dumb to keep track of the Select and Enter button…)

Doug

Let me add that I am using the Mini RR2C’s from MW because they are about the smallest altimeter on the market. I needed that for this particular application.
July 17, 2008 at 3:04 am #48603
Warren B. Musselman
Moderator
I have the same problem with the buttons.

W
July 17, 2008 at 3:59 am #48604
Adrian
Participant
One of these days, maybe someone will make an altimeter that has a USB port on the thing so you can program it with a Palm or a laptop using a nice little graphical interface.

The Parrot’s almost there. It’s currently programmable with a semi-graphical, semi-kludgy combination of an Excel template and Hyperterminal. Jim Yehle is working on a GUI to help with that.

The programming is only necessary if you want to change the deployment defaults. The mach inhibit is automatic based on the accelerometer.
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