NARCON 2017?

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SCP

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Why is this event so quiet this year? I am really interested to hear if anyone attended.
 

rharshberger

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Why is this event so quiet this year? I am really interested to hear if anyone attended.
So far the only infor we've gotten has been some pics of 2 new Aerotech Motors (one, a J that is non-Haz shippable), a few pics of the new Quest APCP low power motors, and a pic of the forthcoming Jolly Logic Altimeter 4 and an announcement that a new version of the Chute Release thats smaller is forthcoming.
 

jsdemar

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It was fun. Well-run event with many good presentations. Banquet dinner with keynote speaker Lee Piester, Centuri founder, was great.

The real Black Brant from Wallops in the parking lot was a pleasant surprise.
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Jim Barrowman talked about his famous stability estimation equations.

Phil Eberspeaker, NASA Wallops Sounding Rocket Manager, was my favorite presentation.

Ed LaCroix gave a thorough overview of the new NAR Rocket Competition rules going into effect after NARAM this year.
 

SCP

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I hope to hear Tim Van Milligan's study/report on the Airfoil Rail guides went well. I hope he had still presented............
 

dcullen

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The best surprise with the Black Brant was FCPD showing up to at the behest of the FBI to investigate the rocket in the parking lot.
 

lcorinth

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Tim Van Milligan did some magic tricks...

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(Kidding. He demo-ed doing epoxy layups for superlight FAI competition models).

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The Rocketry Show interviewed Jim Barrowman...

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It was a really great conversation, both during and after recording. Super approachable, very nice man. Episode to follow soon.

The vendors had some cool new stuff coming out, including Jolly Logic (much smaller altimeter this year, much smaller Chute Release - probably next year), AeroTech (can you say non-HAZ J motor?), North Coast Rocketry (Hobgoblin) and eRockets.

And the museum was awesome.

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The R&D stuff was fascinating, too. The whole weekend was great, but getting to chat with James Barrowman was worth the whole trip for me.
 

GuyNoir

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Phil Eberspeaker, NASA Wallops Sounding Rocket Manager, was my favorite presentation.
Wasn't he just fantastic? It was great to find out they're still doing it the same way as when Dad worked there. Inexpensive (relatively), fast and flexible.

Chris Flanigan's helicopter duration talk was good, too. As was his R&D presentation on pistons.

All in all, a GREAT weekend!
 

SCP

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I have to get there next year. Still stuck in Taiwan on an extended business trip (darn day job).

I was talking with Tim Van Milligan prior to the event and he was planning a presentation on a drag study done on the airfoil rail guides. Anything happen on that subject? Maybe I will ask his permission to post it here.
 

lcorinth

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I have to get there next year. Still stuck in Taiwan on an extended business trip (darn day job).

I was talking with Tim Van Milligan prior to the event and he was planning a presentation on a drag study done on the airfoil rail guides. Anything happen on that subject? Maybe I will ask his permission to post it here.
Yeah, that one was really interesting. He examined drag on 1/4 inch launch lugs vs. rail buttons vs. rail guides, and included the airfoiled buttons. It had some interesting and surprising results.

Nutshell: Rail buttons had the highest drag by far (in a computer simulation), followed by rail guides and airfoil buttons (though I don't remember exactly the order or the figures), followed by launch lugs. Long lugs have less drag than short ones, and angling the leading edge at 45 degrees reduces drag, but angling the trailing edge forward by 45 degrees actually increases it, while angling it back (i.e. to match the angle of the forward swept end) reduces it further. A fillet appears to reduce drag on a lug. An internal chamfer increases drag, while rounding the outside forward edge decreases it.

Ideal looks like a longer lug, both ends swept back by 45 degrees, with the leading outside edge rounded and the whole thing filletted.

Of course, this is based on a computer airflow simulation, and may or may not really apply to real life. Also, to get good numbers, he increased the size of the simulated model by (I think) about 10X. Really, wind tunnel tests and flight tests may be necessary to determine if the simulations are correct, and how much if at all actual flight would be affected.

Oh, and rounding the top edge of the airfoiled buttons also seems to help.

The whole report will likely be the topic of a forthcoming Apogee newsletter. I thought it was great, because I've seen people claim that rail buttons have lower drag several times, but to my knowledge that had never actually been put to the test. I'd like to see more.
 

SCP

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You can't argue with science! Testing would help understand the accuracy and true impact on flights, for sure, but the physics is real. At least at subsonic speeds, and if we are in fact not in too much of a boundary layer effect on the airframe........ A lot of it is personal preference, and there is always the argument about "how much difference does it REALLY make". Heck some people think one design or the other is just ugly, so that is enough reason in itself. It is great that he finally did the analysis, if I had posted CFD results it would for sure appear biased!

Since discussing that with Tim, I am considering adding a rounded edge to the top. One small detail to make it the best product possible for those who like the airfoil guides.

It's great you got to be there, hope I can attend in the future, it looks so interesting. I can not believe Barrowman was actually there.
 

Space Ranger

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A lot of it is personal preference, and there is always the argument about "how much difference does it REALLY make". .
Interesting - did the study focus on comparing the aerodynamic drag after the rocket leaves the rod/rail or also include the differences in frictional surface drag while on the rod/rail, as well as differences in having/not having rod whip, etc?
 

SCP

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What I saw from Tim (prior to what was to be presented at NARCON) was only considering drag forces once off the rail.
 

jsdemar

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I was talking with Tim Van Milligan prior to the event and he was planning a presentation on a drag study done on the airfoil rail guides. Anything happen on that subject? Maybe I will ask his permission to post it here.
I missed the first 5 minutes, but from what I saw he simulated the drag force of the lug shape only. He didn't show the relative affect on the overall drag of a typical rocket. Also, the results didn't appear to be scalable beyond the relatively low velocity he used in the simulations (affect of Reynolds number).

As measured in a wind tunnel, a launch lug adds about 30% to the Cd of a small rocket. (https://www.interactiveinstruments.com/pdfs/28.pdf). Rounding or tapering the lug is in the noise.
 

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