L3 Countdown

[slipstick]

FYI, I have 6 each 5mm diameter static bleed ports evenly surrounded around the avbay.

ROOT CAUSE OF PREMATURE DEPLOYMENT IS NOW KNOWN

No need to continue to speculate. I will provide more data after a few more tests tonight, and how to prevent it.

[Warren B. MusselmanModerator]

Good deal – can’t say I’ve ever seen that many, but that’ll certainly do the job.

[Conway StevensParticipant]

FYI, I have 6 each 5mm diameter static bleed ports evenly surrounded around the avbay.

ROOT CAUSE OF PREMATURE DEPLOYMENT IS NOW KNOWN

No need to continue to speculate. I will provide more data after a few more tests tonight, and how to prevent it.

Mike,

6 x 5mm? What is your avionics bay specs? Length and Diameter?

[SCOTT EVANS]

That’s an interesting thought Scott. My very first dual deploy bird had only a single altitude bleed hole into the avbay and it fired its charge on the pad when a gust of wind hit. Since then I’ve generally gone to 2 or 3 holes equally spaced around the avbay and have never had that kind of problem again. However, it was a specific altimeter that was known to have this problem – not a Missileworks.

Warren

More than one hole? That wasnt in the directions for any of my rockets!8O

[Warren B. MusselmanModerator]

Oh yeah, it’s also just as important that you dont have TOO much port area. Too much or too little can confuse the altimeter.

Warren

[Bruce R. Schaefer]

Forget all this rocket stuff… there’s one really important point… why do I look like Kenny in South Park in Mike’s picture? 😯

I use three, on this next rocket, they’ll be calculated using MWC’s formula.
It gives me (3) 3/16″ to 13/64″ for a 219.7 cubic inch volume.

[Art HoagParticipant]

Forget all this rocket stuff… there’s one really important point… why do I look like Kenny in South Park in Mike’s picture?

Awesome!

[Anonymous]

I’ve used one static port on probably 95% of my rockets. I did use 3 on my L3, but I think that is the only time I did so. That was a very large ebay, and the requisite hole was bigger than I felt comfortable with.

Jim Amos once told me that it is “OK to have any number of ports, as long as it is NOT 2 ports”. IIRC he was concerned about winds moving through under certain circumstances. He was OK with 1, 3, 4, etc. I also believe this info was in his older manuals? I have them downloaded on my other computer, I can dig that up sometime if necessary.

Everything I have read indicates that too much area is bad, especially on high speed or high acceleration flights. I just had a conversation on this last week w/ Peter Lawall (PerfectFlite).

JW

[slipstick]

Mike,

6 x 5mm? What is your avionics bay specs? Length and Diameter?

5″ diameter by 12″ Long. Here’ s the MW Guidlines with my calculations in red (FYI, all this is on my web site):

[edwardModerator]

So you have .588 in^2 as your area that you need in holes. So now you wanted 6 holes around the airframe. This would be .588 in^2 /6 or .098 in^2 for each hole. A = pi*r^2 so r = SQRT(a/pi). Therefore we get r= SQRT(.098/pi) r = .1766 in. That is the radius, so for diameter that is twice so that mean each hole would have to be .353 in. Interesting that the two formulas get two different answers.

Edward

[Author]

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