pop lugs for hpr

railbuttons.com pretty much serves the needs that the pop lug would gain on hppr.

real good price too !

I was wondering about the drag effects that would be generated at the speeds that HPR attains.....at 500-900 mph.....

wouldn't rail buttons exposed to the airstream produce drag effects? causing the rocket to rotate ?

seems to me the only time you might want some "controlled" roll/spin on boost is during higher wind conditions....

shockie B)

well, in the perfect world, that is true. however a 5.5 rocket with 1000 series buttons would "see" very little drag. the button is a very good design to reduce drag.

also, acme makes some "spiky" looking attachments that some feel are better at reducing drag.

I personally don't think there a real gain other then close to theroritical with the pop lug on rockets larger then say 38mm or 54mm.

If I was going for Broke in HPR the tower launcher is the way to go for extreme altitude attempts and is used by the record holders.

most users of HPR are now going away from rods to rails.

If you wanted to design a pop lug, now that I think of it, a button / rail pop attachment might be the way to go.

isn't roll a safety measure in clustered rockets, to help compensate for the effect of an engine failing to ignite? The resulting off-center bias would become a wobble in an otherwise verticle flight, as opposed to an the rocket flying an arc.

- iz

For HPR a tower is usually preferable to a pop-lug, but never underestimate the power of a piston!

Jerry

Yes or spin or rock to the side.

Spinning is UNDESIREABLE for video rockets.

Or lugs on both sides of the rocket to equalize the perturbations, albiet at the cost of drag.

Pardon the tech post!

Merry Jerry

Actually, it doesn't but it makes me think that a wrap around clip could be made to fit a rail quite nicely.

The purpose of a pop-lug or a tower is to not have ANY bumps or protuberances on the rocket that create drag. Rail buttons just replace a draggy lug with a draggy button. For serious altitude competition, you want neither.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Yes it is. however, in all but the most esoteric designs, the video camera, or transmitter antenna will also be sticking out creating drag.

Between Shockie's pop lug and Bob's rail wrap clip , I think we have some extra ideas here worth thinking about.

Art Upton

I guess I'm asking if an exposed launch lug and or rail buttons can produce enough "aerodynamic " forces during boost and coast to affect the rockets trajectory ...

assume a perfect day: absolutely no wind at all....nada....and you lauch the model at 0 degrees.....will the launch lug/rail button cause forces such that the rocket will not go straight up....

shockie B)

It dependsentirelyofthe sizeofthe lugascompared tothe vehicle,themoment arm(length),and thedensity of the rocket.

A Fat Boy almost certainly.

A Dynacom Tarantula almost certainly not.

Pop lug launched 38mm H440 Fat Boys!

Merry Jerry

hmmm a pop rail button ...interesting idea... shockie B)

theroritical

bob: didn't somebody already design/create a wrap around pop lug? shockie B)

is you are worried, why not just put matching buttons on the other side?

Depends on what your definition of "is" is. :-)

Minimal trajectory impact. Significant drag / altitude impact.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Hmmm, got me thinking how to do that.

A pop clip that fits the same rail as a button shouldnt' be too hard.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Wrap around "clamshell" lugs are old news. But they are NOT "pop lugs".

I'm not sure a pop lug would be appropriate for something as heavy as an HPR rocket. I'm sure it could be done, but I'd think the clamshell / rail would be a better alternative.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!