spool rocket stability

[Doug Holverson]

Do spool rockets need to be going past a certain speed to remain stable? And do they start to spin and tumble once they drop below that speed?

 

[user 35280]

I have this spool rocket and used a AT SU F67-4W motor for its first launch. It looked like the speed off the launch rod was fast, but it wobbled pretty good all the way to apogee, arced over and ejected the chute. I’m guessing it went to around 200’. Lots of flame, smoke and noise. Next launch thinking will use a G74-6W.
https://flightsketch.com/store/catalog/loc-cool-spool_152/

 

[manixFan]

That’s an interesting question. I’ve flown a number of low power spools and have never seen one tumble during boost. Just guessing, but I suspect if they have enough thrust to fly, they’ll be ‘stable’, less than that and they would likely end up on the ground and spin around. I’ve flown the Squirrel Works 2-stage spool and it’s pretty slow off the rod, but still plenty stable.

Nice thing about spools, you can test them very easily, almost no prep between flights.


Tony

 

[neil_w]

They're pretty stable on the highway as well.


I would assume that *anything* requires a certain amount of speed to become aerodynamically stable, but in the case of base drag-driven rockets like spools, the speed is probably so low that it stops being a consideration.

 

[Doug Holverson]

I'm so glad that I'm not going up that other lane....

 

[cbrarick]

I wonder how that spool would do with a O motor...

 

[Hobie1dog]

What can you do to a spool to add stability?

 

[neil_w]

What can you do to a spool to add stability?

Add fins. But why would you want to?

 

[Hobie1dog]

exactly

 

[cwbullet]

I wonder how that spool would do with a O motor...

Better think of a recovery system. That baby would crush a vehicle.

 

[lakeroadster]

They're pretty stable on the highway as well.


I would assume that *anything* requires a certain amount of speed to become aerodynamically stable, but in the case of base drag-driven rockets like spools, the speed is probably so low that it stops being a consideration.

Wow.. I was expecting that to end badly. All things considered... it went quite well.

 

[Jeff Lassahn]

The stability of spools isn't more speed dependent than for fins. Both need to get up to some minimum speed for the restoring forces to be strong enough to keep the flight stable, but there's nothing about spools that makes them particularly less stable at low speeds.

 

[StreuB1]

What can you do to a spool to add stability?

High acceleration. Spools gain their stability from base drag. The higher your acceleration, the more apparent base drag becomes.

 

[cbrarick]

So, once again the moral of the story is that Warp9 is your friend

 

[StreuB1]

So, once again the moral of the story is that Warp9 is your friend

I have a spool at home that is ready for the few G339 loads that I've had for over a decade!

 

[Daddyisabar]

I always thought they flew through some sort of incantation and necromancy.

 

[lakeroadster]

I always thought they flew through some sort of incantation and necromancy.

It's witchcraft... burn the skank!

 

[cbrarick]

It's witchcraft... burn the skank!

Now that's just spoolish!

 

[Sooner Boomer]

This is a video of my spool on a .... don't remember, 29mm smokey. The thing wiggles on the way up, not because it's unstable (shut up, John), but because it's as much hot glue and duct tape as original plastic spool. When thrust ends, it stops flying. I'll try to find more videos of it.

 

[Ronz Rocketz]

 

[lakeroadster]

View attachment 497666

Nice, right between the uprights..

and the guy outside, must have a guardian angel..