The Madness has Begun

[Rocketmaniac]

I think after this project, my nickname may change to just Maniac....... Here is a pic of the first few parts for my latest and biggest project yet.........

Guess what it is going to be...... Those of you who were at Whitakers this weekend are not allowed to give it away just yet.........

 

[Mike]

A rocket!



L3 perhaps?

 

[Rocketmaniac]

Originally posted by Mike
A rocket!

Yes......... What kind?

Originally posted by Mike
L3 perhaps?

No L3.......... L2 motor at the most........

 

[jetra2]

I know what it is!

I KNOW WHAT IT IS!!!

But I ain't saying a word cuz it's gonna be sooooo awesome!

Droool....

Jason

 

[Fore Check]

I'm guessing a FlisKits upscale.

With the transition, that would leave the Tres, Drake, Praetor, & Long Overdue (I'm already embarrassed if I missed one.)

I'll guess a Praetor.

 

[wwattles]

That transition shoulder and those tube sizes look just about perfect for a 29mm Tres...

WW

 

[DPatell]

1 vote for 4" to 3" Praetor.

 

[Rocketmaniac]

Fore Check & DPatell

You guys got it right!!!!

This project is going to take some serious design and planning as those fins are going to be huge (well long) ....... The whole "fin span" will be almost 34" wide.....

Much more to come.........

 

[jetra2]

So can we start talking about it Randy?

Let me start...

To solve the long fin and fin flutter problem, here's what I think you might want to do. As you told us at the TRF Meet, build the fin can as one piece and glass the hell out of it. Then, after you've inserted it into the BT, I would say that if you use some Carbon Fiber strips going from fin tip to fin tip, covered in epoxy and then veiled over the entire fin with, say, a layer of 6oz glass then a 1.5oz veil, you should be OK.

The fin can will be as hard as a ROCK this way, but I'm not the expert here. This might or might not work...'

Jason

 

[jflis]

This thing's going to be a hoot

There are definite engineering issues to consider, but it *is* just an engineering problem. Nothing *impossible* here. It will look incredible in the air and will certainly attract gobs of attention!

keep us posted. Seeing the parts in person gives you a real sense of the size of this thing!

jim

 

[Fore Check]

Does this mean I win something?

Seriously, is that a 5" bottom section to a 4" top section?

Also, on your fin flutter issue: Had you considered using lower impulse motors with longer thrusts? You know, keep the velocity down so flutter isn't as big of an issue? Then you'll have truly Praetor-esque liftoffs on a massive scale!

Had you considered using some sort of composite honeycomb for the fins with some kind of laminate covering or "skin?"

With each fin being in the neighborhood of 17" long or wide or however you want to call it, you could almost build them like small model airplane wings with thin, neutral airfoils......

 

[Rocketjunkie]

I still have some 1/32" G10 sheet if you're interested in laminating the fins. I would still run a layer of glass from part way up the fin, across the tube and up[ the adjacent fin. A 54 mm mount would allow motors like the K185 and small orifice hybrids for long slow flights.

 

[jetra2]

I would think that the 1/32nd G10 as a laminate on the fins would be a good idea. I have to disagree with putting a 54mm mount in this rocket for a couple of reasons. The Praetor's lower section is pretty short for a rocket that size. It would leave no room for a chute. The way around this would to eject the chute out of the nose area, but I wouldn't recommend it, because of the LARGE amount of fin area...thinking...maybe you could mount the alt. in the transition, eject the drogue chute out of the nose cone, then eject the main out of the rear of the booster, having it come down in two pieces, since the drogue would be the "main" chute for the nose area. It would be difficult to rear-eject the chute for the booster, but it would be possible.

Think about it...

Jason

 

[wwattles]

I've mentioned this recently in another thread, but I thought I'd mention it again here. Giant Leap Rocketry sells a honeycombed G10 laminate, pre-cut and custom cut to your needs. It might be what you need for those long fins that you have to keep rigid.

WW

 

[eugenefl]

"The Madness Has Begun"??? More like - "The Insanity Continues"!!!

Randy, we're looking forward to seeing this beast take shape. Welcome to the ranks of FlisKits upscale freaks. Looks like this project will be a real challenge. Keep us posted!

 

[Rocketmaniac]

Originally posted by Fore Check
Seriously, is that a 5" bottom section to a 4" top section?

It is going to be a 4" bottom section with a transistion to a 3" section.......... It is the exact same as my LOC Expeditor, so I plan to build the Altimeter bay the same way.......

Originally posted by Fore Check
Also, on your fin flutter issue: Had you considered using lower impulse motors with longer thrusts? You know, keep the velocity down so flutter isn't as big of an issue? Then you'll have truly Praetor-esque liftoffs on a massive scale!

Yes exactly..... I plan to use a 54mm motor mount as I was told there are lot more lower thrust/longer burn time motors for 54mm........ I'll let some of the motor experts suggest motors that are easy to get.....

 

[Rocketmaniac]

Originally posted by Rocketjunkie
I still have some 1/32" G10 sheet if you're interested in laminating the fins. I would still run a layer of glass from part way up the fin, across the tube and up[ the adjacent fin. A 54 mm mount would allow motors like the K185 and small orifice hybrids for long slow flights.

I was thinking about laminatine one piece of 1/8" G10 in the middle of two piece of 3/32" Birch Aircraft Grade Plywood..... This would give me a true "upscale" fin thickness..........

As far a hybrids, I don't think I will have enough room (body tube length)....... The bottom section will only be 22" long.... I need shorter motors.........

 

[Rocketmaniac]

Originally posted by jetra2
The Praetor's lower section is pretty short for a rocket that size. It would leave no room for a chute.

The upper section in my LOC Expeditor is only 14" and I have been able to pack 25' of shock cord and a chute in it....... In this project, the upper section will be almost 21"

Originally posted by jetra2
maybe you could mount the alt. in the transition

This is my plan (great minds think alike!!!!!)

 

[Rocketjunkie]

Originally posted by Rocketmaniac
I was thinking about laminatine one piece of 1/8" G10 in the middle of two piece of 3/32" Birch Aircraft Grade Plywood..... This would give me a true "upscale" fin thickness..........

For maximum rigidity, you want the strong material on the outside. Putting the G10 in the center wastes it's strength. A layer of 1/32 G10 on each side of 1/4 plywood will give the same 5/16" thick fins and be stiffer as well as lighter.

BTW, a K185 is 16" long, including the forward closure.

 

[loopy]

You could also laminate the fins with CF once on the rocket. Run the CF from the tip of one fin, across the BT, and up the adjacent fin. Would certainly stiffen up the fins quite a bit, and help keep them from fluttering. That would also help on the landings. Personally, I think I'd go that route.

Man, I can't wait to see this come together!!!

Loopy

 

[Rocketmaniac]

I just ordered the nosecone and a bunch of 1/32" G10..... Now I just need to find some 1/4" aircraft grade plywood........... (large pieces, at least 6" X 16") I have found 6" X 12" but nothing larger....... any suggestions?

 

[jflis]

Suggestion, from the engineer in me...

Civil engineers discovered long ago that you can NOT remove all the vibration and movement from a bridge. All you can do is minimize it then engineer the design such that it can withstand the vibration and movement that is inevitable. Same thing with sky scrapers...

...same thing with Praetors

Do all the smart things to reduce fin flutter, but recognize that you will not be able to eliminate it completely. If you keep this in mind and engineer a solution that can withstand the inevitable fin flutter then you will have a solid, working design.

just food for thought.

jim

 

[jetra2]

Randy,

Any updates on this beast? I'm not expecting any really, but it would be cool to know if you have done anything with this thing!

Jason