Stressing Quantum tube....

[Justin Horne]

Hi all.

This is just a little notice that PML is actually probably right with their whole "Don't exceed 85% of mach with Quantum" thing, but not by much. Inadvertently, we did happen to actually break mach with a Black Brant VB, and it came out fine. It didn't handle it perfectly though.... When we got it back, paint on the side of the rocket for a length of ~6 inches was cracked off, and even mor paint had lines running though it, like the tube was stressed hard. Either way, that's a fun way to break mach...
So what have I learned from this? In the future, I don't need to build as strong, only just a tad stronger than quantum!

 

[GL-P]

I know a guy who wants to do CAR lvl4 (or TRA lvl3) on a Black Brant VB. It will break mach. I will post after photos as soon as I get them.

Should be real cool!

 

[North Star]

I 'overstressed' some QT last spring when my 4" upscale mosquito 'lawn darted' from 500ft after the Aerotech G64-4W that I had carefully prepped (Hmmm) neglected to blow the nose cone out.

I am very grateful to the QT for disintegrating around the Scotglass/Rebel-Rocketry nosecone as it only suffered a few minor chips (it was the most expensive part of the rocket!). Even 2 of the 3 balsa/G10 laminate fins survived . The QT seemed to have absorbed a lot of the kinetic energy by shattering into many small pieces as it deformed over the rim of the nosecone.

So, whilst I'm not a great fan of QT, I agree it does have its uses

 

[baxterl]

My QT Black Brant VB has a nasty habit of loosing 1 fin per flight, nearly routinely... it also developed cracks in the nosecone end after 10-12 flights and had to be shortened. Again, not a big fan of the QT.

 

[Austin]

The Quantum tube on my rockets has actually held up well. I have several kits from PML, but the most flown and abused is my PML AMRAAM 4. It has seen around 40+ flights, all but two were on J motors and still it stays in good shape. I have flown it on every thing from a J285 to a J460, but make sure I don't overstress the airframe. Sure makes a difference in longevity and is living proof Quantum is good stuff.

Just my 2 cents...

Carl

 

[BlueNinja]

Wowie. I'm lucky to get in 5 flights on most of my rockets. I've heard good things about QT, some review on EMRR (small endeavour?) noted stress testing it in different conditions, like partway frozen, ambient temp, etc etc. I have seen some QT cracks though, I imagine in plastic they would spread easy if you don't reinforce them right away... like a windshield.

 

[GL-P]

Yeah, a problem is that it is quite temperature sensitive.

 

[daveyfire]

https://www.jcrocket.com/blackbrantvb.shtml

'nuff said

 

[Justin Horne]

Wow! I'll remember, not to put a J570 in! What intereste me though is the fact that the quantum stood up to the power, it's just that the fins were ripped off... Well, like was said in the link, the epoxy can't wick in, but I am impressed.. Maybe stronger fin attaching...Hmm that gives me a few ideas....! If only I had enough room...

 

[loopy]

Originally posted by Justin Horne
Wow! I'll remember, not to put a J570 in! What intereste me though is the fact that the quantum stood up to the power, it's just that the fins were ripped off... Well, like was said in the link, the epoxy can't wick in, but I am impressed.. Maybe stronger fin attaching...Hmm that gives me a few ideas....! If only I had enough room...

You could do what Carl does with his fins - Attach them as normal, then fiberglass them internally. Instead of putting the fiberglass on the outside of the tube (which doesn't work very well on QT kits), he runs a strip of epoxy from one fin, across the phenolic motor tube, and up the next fin. I've never seen one of his rockets lose a fin.

Loopy

 

[North Star]

Originally posted by Loopy
You could do what Carl does with his fins - Attach them as normal, then fiberglass them internally. Instead of putting the fiberglass on the outside of the tube (which doesn't work very well on QT kits), he runs a strip of epoxy from one fin, across the phenolic motor tube, and up the next fin. I've never seen one of his rockets lose a fin.

Loopy

To really bind everything together add a length of carbon fibre tape or a couple of CF 'Tows' into the wet resin using Carl's method. (do you call them Tows in the US ... they are 6" clumps of thin CF fibres which just lay in the resin but add a huge ammount of strength. The glider people use them a lot over here).

I found that even though I seriously abused the surface of QT it still tries to reject resin. By bonding all the fins and motor mount together the QT becomes more or less a shroud and the stresses are distributed.

 

[lalligood]

I would have to say that QT has its limitations, however, PML markets QT quite well, clearly outlining those limitations, all of the thing to do with QT, & more importantly, what NOT do with QT. As long as you follow PML's guidelines, most everyone should find it to be a very satisfactory material used to construct rockets with.

Just a little something to keep in mind:
The builder has far more influence on the success (or failure) of a rocket than the material(s) being used.

 

[Ozymandias]

QT just isn't made for mach-busting. Plain and simple. I love it for sport kits but for my high performance rockets it's FWF* all the way.


*filament-wound fiberglass

 

[Stymye]

a good thing about PML is that you can order a kit with phenolic tubes instead at no extra cost (IIRC),,, wrap a little fiberglass on her and "Bob's your uncle!"

If you try to push the Quantum too far .well....thats your own fault
because they clearly and openly post the limits of QT.
but atleast they offer you the choice.

 

[Silverleaf]

How not to stress Quantum Tubing :

1) Serenade the tube with videos of 1/2 A and A flights.

2) Bathe it in baby oil, followed by a hot towel massage.

3) Before the flight, let it watch the Saturn V launch, in super slow-mo..

4) Let it watch a Tube-rated version of Apollo 13

All the above should ensure your Quantum Tubing is as stress-free before flying as possible.

8)

 

[Justin Horne]

Oh i deserved that...