body tube transitions

What is the primary reason people use body tube transitions? I understand looks, and I understand when constraints such as payload dictate, but beyond that I am curious if there is some big aerodynamic function I am missing out on. I would think that the widest part of the airframe is more important than having some partial length narrower, though.

Looks.

TopRamen said:

Looks.

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The only reason I want to use them

It looks cool
In Superroc contests, its a way to reduce weight while still making the rocket ridiculously tall. they're often used in egglofter's for similar reasons: having something that will hold the egg, but still keeping it light.

Nate

If the motor diameter is smaller than the body (parachute duration model for example), then flipping it around, used as a boat tail to reduce the base diameter, reduces the base drag.

watermelonman said:

What is the primary reason people use body tube transitions? I understand looks, and I understand when constraints such as payload dictate, but beyond that I am curious if there is some big aerodynamic function I am missing out on. I would think that the widest part of the airframe is more important than having some partial length narrower, though.

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These guys have it pretty well noted. I am a transition addict and nearly every design I come up with has one to 3. Even though you can do trannys on higher than LPR rockets, it's more widely used in LPR. I'm not sure if there's any aerodynamic advantages to using them, in fact, it might actually hinder with added wind resistance. But in my case, it's irrelevant. I love the variety it gives me designing. Most of my fleet is LPR and I don't do a lot of kits anymore, so I'm always on the drawing board. And I could honestly say 90%+ have at least, one.

Coolness.

Here's one that I hope to build soon.

Transitions that adapt the front of the rocket down (think Norad, Argent) add a lot of drag but look cool. Transitions near the back of the rocket (V2, duration models like mentioned above) help cut base drag, although reducing base drag can reduce stability.

A forward transition that increases diameter from forward to aft has a positive effect on stability.

This thing needs lots of Sanding and then Details and Finishing work,(Spring Work, not Winter), but the Transition here lets me use this cool Nose Cone but still end up with a BT-80 Rocket.

To reaffirm the previous answers--weight and drag (though at the expense of structure). Of course, there are ways to design the transition sections so they benefit neither weight nor drag...

Worsaer said:

Coolness.

Here's one that I hope to build soon.

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You got a Rocksim or Openrocket for that beauty you might wanna share?

This is the first pass of a Rocksim file. I haven't fine tuned it yet - but it's a start.



View attachment IRIS-T_03.rkt

Neat that...