VB Extreme 38
We were talking about adhesive strength and how to test it. Of course, my approach is to do an elaborate test which requires building a whole apparatus. Ed Hackett, in a much more practical mood, said: "just go build a bunch of VB Extreme 38s and put a J350 up the butt!"
I don't think this would really provide usable results, but I did like the idea of a full-on test, so I suggested we have a "strong rocket" contest. Each contestant would build a VB Extreme 38 (or perhaps another kit), then the rockets would be repeatedly launched until only one remained intact. No one else took me up on the contest, but I decided to build my entry anyway.
Of course, I had to paint the rocket yellow and black because they're the trademark Vaughn Brothers colors. Also, this is a nice high-contrast paint scheme to help me find the rocket again.
Love that gray January sky. Reminds me of when I first started in this hobby (last winter).
On February 13, 1999 at the February ROC launch in Lucerne Dry Lake, the Lunar Express flew for the first time. The boost was straight and fast on a J350, a large motor in a small rocket!
|Bursting out of the BMS tower...||the flame is longer than the rocket...||and it's out of there!|
The rocket was way gone on a J350 and went 11,703 feet high (according to the ALS20). This is craziness, but that was the whole purpose of the rocket. It took is more than an hour to find the rocket; we drove out on the lake three times, farther out each time. Finally, we spotted it about ¾mi away from the launch site! This rocket really needs to be recovered with a Walston radio unit. The rocket was in perfect shape, although I lost the motor casing (which is probably why it drifted so far). Now on to a J570!
The kit is well designed, basically a Loc/Precision 38mm motor mount tube as the airframe. This makes a very strong body tube, which is a good idea since this is a rocket meant to go high. Since this is a minimum diameter rocket, the fins need to mount on the outside. In addition to the usual epoxy bonding and fillets, I decided to go wild and reinforce the fins to the body tube with 1" reinforcement strips made with Kevlar®* fibers. Then I covered the whole thing with a double wrap of 4oz cloth and a covering wrap of 2oz.
|Close-up of the fins showing the Kevlar reinforcing strips.||The rocket before painting. Note the full composite wrap.|
I think the fins will stay on! This was the real challenge here; making a minimum diameter rocket so that the fins were really not going to come off. Perhaps this was overkill, but this thing is certainly not coming apart easily. We'll see when I fly it on a J350, and maybe even a J570.
* KEVLAR® is a trademark of E.I. du Pont de Nemours and Company.