L2 low altitude rocket

[techrat]

So what would you call the Celtic Thunder.... ring or non standard tubes...
View attachment 540821

I'd call it a flying Venn Diagram.

 

[Lt72884]

Hi @ThirstyBarbarian and anyone else,

I am not saying your are wrong about the Warlock's and the Doorknob's being basically longer and shorter versions of each other.

However, could you please explain that statement in a little greater detail. Yes, LOC/Precision produces both rockets, each of which has the same diameter, and the shape of the fins is the same in both kits. On the other hand, the Doorknob has four fins while the Warlock has three. Moreover, the Doorknob has two body tubes and the Warlock has only one.

Aren't those important differences? Maybe they're not. I am asking a genuine question. I don't know, but I am curious as to your opinion.

Thank you.

Stanley

4 finned rockets can have more stability, but your drag is increased roughly 20%. So using a rocket with more fins increases the drag, which is important concept as you say As the body lengthens, stability is important so having 4 fins with longer bodies is nice. Look at the ISQY tomahawk missile, not the cruise missile, the actual rocket. there is a reason it has 4 fins and that most military rockets have 4 fins. I have a paper on this somewhere of why they require it.

 

[MetricRocketeer]

I have a paper on this somewhere of why they require it.

Hi @Lt72884 and anyone else,

Thank you for your interesting reply.

If you could dig up that paper, I would be curious for a link if possible.

Stanley

 

[Lt72884]

Hi @Lt72884 and anyone else,

Thank you for your interesting reply.

If you could dig up that paper, I would be curious for a link if possible.

Stanley

If you had a gimbling nozzle, you could technically get away from fins and just use the nozzle to steer the rocket.. sorta speak haha

here is an interesting read as well.

M26 Multiple Launch Rocket System (MLRS)

www.globalsecurity.org

 

[MetricRocketeer]

Thank you, @Lt72884. I will look at this.

 

[ShadowSpire48]

LOC 5.5" Goblin. Less than 2K on a J425, easy peasy

 

[Tractionengines]

3 vs 4 fins. Lots of information in this thread. (Also lots of opinions...take them with a grIn of salt.)

3 vs 4 fins; Why do space programs prefer 4?

From what little I know, if three fins are properly sized and shaped, it will work just the same, and maybe better than four. Yet, all of the NASA/military designed rockets seem to use four fins. Is it because they are active control surfaces and its easier along an axis? But even sounding...

www.rocketryforum.com

 

[Off Grid Gecko]

Generally speaking, 4 fins provides somewhat easier steering calculations but I don't think that's prolly a big deal these days (if you are using rudder type of steering). Most 4fin missiles I've seen also have four canards up front to steer. 3 would require some mixing while 4 makes orthogonal "pairs." Same R/C helis use three servos for the swash plate and requires mixing, while some tiny ones have only 2 servos and they are laid out 90deg to each other.

 

[Sooner Boomer]

The difference between a ring fin and a tube fin is that a ring fin is a single ring that is a larger diameter than the body and goes around the body tube with the body centered in the ring,

Usually, this is true. Of course, there are exceptions. For example, the "Corkscrew" is a ring fin with the body attached directly to the ring.

Corkscrew 2 Build Backstory

Here's a fun, easy to build design by Bruce Levison . The CORK SCREW won him first place in the FlisKits Design of the Month Contest in...

modelrocketbuilding.blogspot.com

 

[Charles_McG]

I went with drag for my L2. Tubes and fins. First flight was L1 territory to prove the model.

 

[Rob Campbell]

I went with drag for my L2. Tubes and fins. First flight was L1 territory to prove the model.
View attachment 541319

Upscale Pegasus?

 

[Charles_McG]

Upscale Pegasus?

Yep. Parts from a MDRM, a Leviathan, some extra tubes and a lot of laser cutting.

 

[Bill Hanson]

Generally speaking, 4 fins provides somewhat easier steering calculations but I don't think that's prolly a big deal these days (if you are using rudder type of steering). Most 4fin missiles I've seen also have four canards up front to steer. 3 would require some mixing while 4 makes orthogonal "pairs." Same R/C helis use three servos for the swash plate and requires mixing, while some tiny ones have only 2 servos and they are laid out 90deg to each other.

Another reason is that 3 fins requires a greater span than 4 fins, which makes fin flutter more of an issue,
Won’t matter for “low and slow,” but worth keeping in your cross check.