Anak Endeavour

[EeebeeE]

When Karakatau erupted in 1883, the Island of Krakatoa was obliterated. Then in 1927 after a series of eruptions occurred, a new island appeared. The locals called it "Anak Krakatau" which means "Child of Krakatoa." Today it rises 600 feet above the ocean and is the fastest growing volcano on the planet.

My PML Endeavour had 2 flights. Both were "less than successful." The final flight showed that, yes, it is possible to zipper Quantum Tube. The fincan was destroyed. However, because I made repairs on the last flight and also because I changed my mind after the kit purchase and bought a second 54mm motor tube, and because other parts survived like my AV Bay, the chute, shock cords, nose cone, and a section of QT, I have the parts to build a slightly smaller rocket. it is the Child of my Endeavour, which will hopefully fly to altitudes higher than those of its father. It looks like a streamlined Alpha, and I hope it will be done in time for LDRS.

What do you think?

[GDJ]

I think you better get busy and build this one! Looks good to me!

[JDcluster]

You might want to change up the fin design a bit.....long raked out fins tend to want to flutter.
How high are you planning on flying to?


JD

[EeebeeE]

It is also made from Quantum tube so this is a long burn lover. Fins are 1/8" birch plywood. I have a J210 on order, although I might save that and go with a J140 or a K160.

[Buckeyegator]

JD is right about flutter, but I might add that those long rakish fins have a marked propensity to snap off when making ground contact (unless you have them heavily glassed).


Terry

[EeebeeE]

But they look so cool.

Plus, the main chute is oversized. Landing velocity is only about 12 mph. I am using an Adept 22 altimeter for it, set to 600'. Then a big burly 54" PML parachute opens up and it should gently touch down.

The fins do help give it some strong stability by pulling the CP aft while leaving the CG forward. I may get some weather cocking if it is windy, but that should help bring it closer to the pad when it lands.

This is not a high performance rocket by any stretch, but it should fly very well at slow speeds, and make a slow and graceful final descent.

[Buckeyegator]

Evan:

What part of Ohio? DO you fly with Mars or go to Geneseo at all?

You may know of Rich Pitzeruse. He and I use to upscale Estes Mosquitos. I think the largest I did was a 4 inch diameter. I know he did a 7.5 inch upscale. When he got to that size, Flutter was ALWAYS an issue regardless of motor selection. Landings were interesting. I see the same issues here. What material is used for your fins?

Terry

[EeebeeE]

I am originally from the Dayton OH area, but live in Western NY. I am a member of MARS and fly at Geneseo often.

This rocket is 4" in diameter. The fins will be about 18" long and will be cut from 1/8" birch plywood. They might be coated with a 24-hour marine epoxy that I have because it soaks deep into the wood and bonds the wood fibers together. Since is is being built for longer burning motors, I have to pay some attention to weight, so adding glass cloth on the fins isn't possible.

Fin tabs are 6" long and they will be glued to the motor tube. Instead, the entire fincan will be filled with epoxy foam. I am not planning on taking this thing anywhere near a transonic speed, so it will generally fly on 280 avg. NS or less. Actually, I think it will fly beautifully on a CTI J140.

I did think about shorter gizmo-shaped fins, but this design gives it more stability during slow launches, apart from weather-cocking during a breeze. The shorter fins also allow it to go faster, which means a push near transonic speeds, and that is a no-no with QT. Plus, I think it looks cooler.

This rocket is the poster child for compromise.

[JDcluster]

The 1/8" will be too thin. I highly recommend 3/32" or greater.
Fiberglass may help.


JD

[nh4clo4]

The 1/8" will be too thin. I highly recommend 3/32" or greater.
Fiberglass may help.


JD

I second that. I was thinking 1/4" myself.

Coating the fins in epoxy will add more weight in the back of the rocket for only a small improvement in strength. I would go with the stiffer (thicker) fins for probably the same overall weight.

[EeebeeE]

Keep in mind that the Endeavour had 1/16" G10 FG. And again, this thing is not going to go that fast.

[MasonH]

The 1/8" will be too thin. I highly recommend 3/32" or greater.
Fiberglass may help.


JD

3/32 is smaller than 1/8 though...?

[EeebeeE]

So I take it my 1/8" should be OK.

[JDcluster]

I meant to say 3/16".
I have a rocket that I built back in 1996 that has 3/16" fins that I coated with epoxy and still flying today.

JD

3/32 is smaller than 1/8 though...?

[EeebeeE]

Going with the 1/8, although the fins have been changed considerably. I assembled the rocket over the weekend, and will coat the fins this evening. The fin tabs are 6" long. They are epoxied to the motor tube. internal and external fillets are done with Liquid Nails (this stuff is incredibly strong...on my 4" LOC V2, I still have yet to have a crack in the fillets, even after a harder than desired landing). The fincan is then filled with epoxy foam.

My hope is to fly it at LDRS. I have a J210, although I might opt for a J140 or a K160 instead. It is pretty light weight so the lower average NS motors should not be a problem. The design configuration shows performance estimates with a K160. This thing is not going to break any speed records. It will never meet a V-Max. I don't want it to go transonic because of the QT so I set this up as more of a long burn beast. That should hold down the fin flutter as well as the less-raked fin design.

It is a classic dumpster dive of a rocket where I made due the materials I had to reconstruct something from the remains of a shredded rocket.

[EeebeeE]

This is before paint. Should be fun to watch it fly, and I want to have a camera pointed down so I can catch the fin flutter.