Anima Mundi

[mikec]

Even Fusor and these space age glues have a limit...and solid fiberglass airframes allow NO resin absorbing.

Practically all aerospace structures (airplanes, spacecraft, large optical systems) these days use composite-to-composite or metal-to-composite epoxy bonds as primary structural elements. All materials have limits but adhesive absorption need not be a critical factor with the right surface prep and the right epoxy.

I'm skeptical that at the low speeds this will reach aeroloading will present much of a structural load on the NC. The best way to limit loads on the NC bulkplate is to make the NC as light as possible. That said, I haven't seen the cone in detail and I don't know if it's flightworthy or could be made so.

Best of luck!

 

[Feckless Counsel]

TRF,

Here's the plan for fixing that cone:

1. Cut off the tip. Fill the end with a solid plug and cap with 3/4 inch plywood plate. Run 3/8-16 rod from the plywood plate down to the shoulder. At recovery we go from shear on adhesive joints to compression of the cone's arch.

2. Pick up the 3/8-16 rod with a few disks to stiffen the cone middle. Bond those to the cone using aggressive solvent based adhesive.

3. Patch the shoulder using glass cloth and filled epoxy.

4. Carve a new tip from 20-pound foam. Soak with epoxy to harden. Glue to plywood tip plate.

Feckless

 

[GregGleason]

Sounds like a good plan to rescue and make the nose cone stronger. It could have been a "blessing in disguise" after all.

You do realize that if you have a successful flight, you will have to change your handle. At least to "Not so Feckless Council".

Greg

 

[Feckless Counsel]

Greg,

Thanks for the vote. Below are pictures of the bris and retrofit.

1. Trimmed end of the nosecone. Sort of an ugly plug there already? I tested that plug with a dowel and hammer. Seems solid.
2. Pieces of the nosecone tip. No wonder it split.
3. Cavity filled with 50 milliliters of Devcon 14320 and capped with plywood plates.

Feckless

 

[JStitz]

Feckless, this is a blessing as you gain control of ALL parts of your rocket now.
The Cone was meant to be a prop and look good from the outside..can't blame the boat guy who was also NOT a real Rock and Roll propmaster.

You aren't still pressured by Red Glare are you...Honestly at this point your friends and followers on The Forum want you to make this beast work right...Take your time man and do what you gotta do to make it right. You can't launch till you feel it's right.:dark:

 

[Feckless Counsel]

JStitz,

Will not fly until the work is complete, meets my feckless standards, is checked by the RSO, approved by the TAP and Mikec stomps it a few times.

And Mike! I've learned to use and understand those smiley faces::wink:

Feckless

 

[Feckless Counsel]

TRF,

Repair of the noscone is near complete. Pictured below:

1. Cracks at the shoulder are repaired. Surface sanded back 10 inches from the shoulder and down to raw glass.

2. New bulkhead installed, bolted through to the tip and adhered using Devcon 14320. I's solid!

3. Shoulder glassed with two turns of style 3733 fabric.

Feckless

 

[daveyfire]

I like your plan for recovery. I'm working on step 1 The repair looks like it's coming along -- do we still get to see it next weekend?

I just finished packing charges for Todd's rocket... Jerry is making progress on his Iris... Todd made a pair of igniters and got a pretty sweet bruise from the P motor... I have one last batch of propellant in the mixer, ready to come out. RG is shaping up to be awesome!

 

[mikec]

Repair of the noscone is near complete.

Looks great! Hope you're not too itchy from sanding that fiberglass!

 

[Feckless Counsel]

TRF,

Gave up on Red Glare this Monday past. I believe I could have made that date. But I also know I shouldn't. I've got 5 months and $1800 in this project. No sense in pressing onto disaster. Maybe LDRS 31 in July?

Feckless

 

[THarrison]

TRF,

Gave up on Red Glare this Monday past. I believe I could have made that date. But I also know I shouldn't. I've got 5 months and $1800 in this project. No sense in pressing onto disaster. Maybe LDRS 31 in July?

Feckless

Any additional progress on the beast? It was nice to meet you at Red Glare (my team flew the Green P).

Todd Harrison

 

[Feckless Counsel]

Todd,

Thanks for your inquiry. Update is the rocket is in paint and, hopefully, will launch at LDRS on 14 July.

 

[SMR]

Update is the rocket is in paint and, hopefully, will launch at LDRS on 14 July.

Have a great flight, Geoffrey. We are all rooting for you.

Sather

 

[Feckless Counsel]

TRF,

Any advice on venting? Bulk-plate and side wall area in this beast are huge. The numbers tell the story.

1. Flight to 4000-foot AGL. Pressure drop is 2 PSI in 15 seconds.
2. Bulkhead area is 68 square-inches.
3. 2 x 68 = 136 pounds pressure on a single bulkhead assuming airtight seals.

Consider I am using 4 each 4-40 Nylon 6/6 shear pins. I have 2 questions:

1. Is the separating force at ascent 136 pounds or twice that, that is to say 2 bulkhead pressures?
2. What is the maximum time constant to vent this design?

Finally I have assumed, despite the huge force integrated over tubes internal area, the pressure to sidewalls is still just 2PSI. No problem for homespun fiberglass, correct?

Feckless Indeed

 

[dixontj93060]

Four 4-40 shear pins should hold a minimum of 200 lbs which should be OK compared to your 136 lbs limit. But why not put a small (1/16" hole) for venting in each compartment just to be safe?

TRF,

Any advice on venting? Bulk-plate and side wall area in this beast are huge. The numbers tell the story.

1. Flight to 4000-foot AGL. Pressure drop is 2 PSI in 15 seconds.
2. Bulkhead area is 68 square-inches.
3. 2 x 68 = 136 pounds pressure on a single bulkhead assuming airtight seals.

Consider I am using 4 each 4-40 Nylon 6/6 shear pins. I have 2 questions:

1. Is the separating force at ascent 136 pounds or twice that, that is to say 2 bulkhead pressures?
2. What is the maximum time constant to vent this design?

Finally I have assumed, despite the huge force integrated over tubes internal area, the pressure to sidewalls is still just 2PSI. No problem for homespun fiberglass, correct?

Feckless Indeed

 

[Feckless Counsel]

Tim,

Venting is absolutely necessary. Question is how to make it.

Please check my numbers as I may have a math error:

Diameter = 21.75
Radius = 10.875
Area = pi*(10.875)^2 = 372

Pressure = 743 pounds per bulkhead

Feckless

 

[GDJ]

Tim,

Venting is absolutely necessary. Question is how to make it.

Please check my numbers as I may have a math error:

Diameter = 21.75
Radius = 10.875
Area = pi*(10.875)^2 = 372

Pressure = 743 pounds per bulkhead

Feckless

Yeah, I was doing the math too, and my numbers were reasonably close to yours.

Based on the pressure build-up inside vs. Outside pressure at apogee, I would say you would probably need at least two 5/16" orifices, minimum. Maybe three. That's alot of rocket to vent in a short time.

But, as always, my math is not spotlessly perfect, so if somebody else can confirm or refute this, please say so before Feckless launches.

 

[dixontj93060]

Look here: https://home.earthlink.net/~david.schultz/rnd/pressurelag/parachute.html. (Sorry, I do not have time to find my spreadsheet implementing this lag filter as I am at a party with my family--note that a few months ago some of David Schultz units were off on his web page. I informed him of the error; he might of fixed it by now.)

Tim,

Venting is absolutely necessary. Question is how to make it.

Please check my numbers as I may have a math error:

Diameter = 21.75
Radius = 10.875
Area = pi*(10.875)^2 = 372

Pressure = 743 pounds per bulkhead

Feckless

 

[dixontj93060]

Hey, seek and ye shall find... Here you go Geoffrey, here should be all you need (enter your sim time/altitude flight profile in columns then airframe parameters in yellow cells).

Look here: https://home.earthlink.net/~david.schultz/rnd/pressurelag/parachute.html. (Sorry, I do not have time to find my spreadsheet implementing this lag filter as I am at a party with my family--note that a few months ago some of David Schultz units were off on his web page. I informed him of the error; he might of fixed it by now.)

 

[Feckless Counsel]

TRF,

A picture with paint. Decals revealed at the field?

 

[Wayco]

Do you have any way to weigh that monster? Did you make your 110 lb. estimate? Just wondering what kind of motors it will take to get it off the ground.....

 

[GregGleason]

:surprised:

Well ... I'm impressed!

:clap::clap::clap:

It will certainly be the one-everyone-will-want-to-see on launch day.

Greg

 

[Neuport]

I'm guessing DeWalt decals?

 

[Coop]

Bravo! Well done! Wish I could be there for the flight... look forward to the range report and photos/video!


Later!

--Coop

 

[JStitz]

I'm glad you took your time with this build and didn't OCD rush it for a quick launch date.
Forgive me if I missed something with the pressure talk, but did you end up doing a small 4" diameter altimeter chamber on one side of the tube? Or did you go full diameter?:y:

 

[Yoehahn]

LDRS REPORT: Biggest CATO I have ever seen... started one helluva fire, and it just disassembled on the pad

 

[Barracuda]

Very impressive..so this is whats been going on since October

 

[eggplant]

Truly a tragedy! I am interested in what the cause of the failure was. Did anyone get photos or a video?

 

[RoyAtl]

Try this link:

https://www.facebook.com/photo.php?...0920177747167.400688.661337166&type=1&theater

Not sure if she set public permissions.

 

[Rex R]

nope, tis not availible to non-members.