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- Feb 19, 2009
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If you need more data . . .
https://www.rocketryforum.com/threads/iris-sounding-rocket-scale-data.155495
Dave F.
Oh yeah Dave! That’s the data / drawings that inspired me to try this. I’m going for a little more than “sport scale” since we have decent drawings and pics of the Iris.
I got some teeny screws for some nose cone detail when I get to that point. Will be some of the finishing touches If the build goes as planned. Nice day in Oklahoma so I started to epoxy the MMT and a 54/38mm adapter.
Undecided if I'll build the booster too. If I do, it will probably just be for display. It does look cool with the booster though. At this scale, I'll have to check if the booster motor tubes are a common size....that will simplify my decision.
4” full scale ... 4/3=1.3” dia for the booster motor tubes.
So BT-55 tubes would be perfect!
With the fin gap at the rear, that's a fair amount of unsupported fin area back there. Hope nothing unfortunate happens
I’ve got some ideas on how to make the fin gap a little stronger but still look scale. Hard to describe. I’ll post pics when I get to that point.
Here’s my idea. It took a lot of effort to make it look this bad. The Dremel router is not easy to control. I clamped down a fence but it still looks a little crooked. The tolerances are so tight...oh well. Probably go with a couple of drilled holes and a coping saw on the other fins.
Where’s your sense of adventure? I’m going to try it....maybe it’s my Scottish stubbornness. What’s the worse that could happen?
It’s hard to gauge if you’re serious Dave...you did put a
LOL at the end, so I’ll assume you meant it with humor.
I wouldn’t do anything I thought was dangerous or irresponsible.
Would you feel uncomfortable with swept back fins that looked like this?
I won’t disagree that the fins are weakened by these modifications, but I don’t think it’s a recipe for disaster. If the fin tip hits on landing, it would have the same moment and shear as the swept fin. As far as flutter goes, it would be similar to the full scale design.
These fins are TTW and notched into the centering rings. I will fillet all the internal joints with epoxy.
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