"LowBotomy" --- a MPR Parkflyer

[qquake2k]

What a neat design and a great looking rocket!

 

[ckreef]

So the F39-6 is acting like a "6" for you? I just got some and see how they're marked "-6(3)* *NAR certified time" ... how confusing & noncommital.

Mine were marked the same. The NAR certification data found here https://www.nar.org/SandT/pdf/Aerotech/F39.pdf lists the average delay time for an F39-6 as 6.27 seconds. Of course that certification was done in 1994.

Although I have flown her four times using a Altimeter 2 I really only have two flights of data (one I forgot to turn on the Altimeter and another it didn't record my apogee to ejection time.) So using my two good data sets I added together my coast to apogee and the apogee to ejection times and this is what I got.

F39-5 gave me a delay time of 6.5 seconds
F39-4 gave me a delay time of 5.3 seconds

I did get better with the process of cutting down the delay with each successive flight. Unfortunately the data from my last two flights is the data I don't have. Of course 2 sets of data is much to go on but that's what I got so far. Will post more data as she gets more flights under her wings. Will also try and make and post a flight log later this weekend.

 

[bill_s]

OMG, so a "-6(3)*" is actually more like a 7 ... maybe Aerotech delays increase with age?

The NAR certification data found here https://www.nar.org/SandT/pdf/Aerotech/F39.pdf lists the average delay time for an F39-6 as 6.27 seconds. Of course that certification was done in 1994.

Yeah, but I think that's for the "-9(6)*", since that shows 3, 6, and 9 but the packages show 6(3) through 12(9).

 

[ckreef]

I understand what you're saying but my F39-6T(3)* is definitely more then a 3 second delay time. I would love to hear someone from Aerotech explain how they label their packages. Even if I took my reload as a NAR certified 3 second delay the certification document only gives an average of 3.17 seconds and I am getting basically double that. Something does not add up here even if you account for a 2 second margin of error.

I have 5 more F39-6T(3)* reloads waiting to launch. They will get launched the 1st week in April. Hopefully I can get good data for all 5 launches.

 

[ckreef]

Attached is a flight log for my first 4 flights. After reviewing the data and the videos I noticed that flight 4 w/ a delay cut down to 3.5 seconds, ejected just prior to apogee (which is why I have no data for flight #4 Apogee-> Ejection). From now on I will stick to a 4 second delay.

More data to follow as the launches occur.

View attachment FlightLog.pdf

 

[bill_s]

From what I've been able to figure, the parenthetical time should be ignored. Maybe they were trying to squeeze in the -12 on the original certification or something, or were trying to explain why the checkboxes moved. The -3 was decertified for competition is '98 or 99. The -6 and 9 were also in '02 when the factory moved but then recertified in '04 (not the -3). Googling the -12, one vendor appears to have a "place holder" in their catalog for it but no one else, so apparently it was never produced.

The fact that these 24 mm offerings were all developed almost 20 years ago makes it seem unlikely there will be any more, in particular new options for the 24/60.

 

[ckreef]

Bill thank you for the short history concerning the delay times and certification.

Well I couldn't stop myself and had to launch her 2 more times today. Wind was 12mph. The 1st flight a parachute line got caught on my altimeter hook so she came down hard and straight on her bottom end. I was glad I made the BT aft end double thick. On the 2nd flight she drifted just to the edge of the bush line.

Launch pic from 1st flight of the day (Flight Log #5)



2nd flight of the day bush landing (Flight Log #6)

 

[ckreef]

Here are some pictures from flight number 8.

 

[ckreef]

 

[ckreef]