Construction Rating: | starstarstarstarstar_border |
Flight Rating: | starstarstarstar_borderstar_border |
Overall Rating: | starstarstarstarstar_border |
Manufacturer: | Public Missiles |
Brief:
This is the Big Black Brandt X(10) that PML offers. It is a scale high power kit that takes 29mm I200's to 54mm J800T as a stock kit. The larger 54mm extended Kwik-Switch must be purchased to run the 54mm "Mega System" which will fit the 1706 and the 54mm/2560 K700W motor. I did not purchase this and built the kit close to stock.
Construction:
The kit came from RocketSilo all boxed up, and it is so large it comes in 2 bags. 1 bag for tubes, 1 for parts and nose cone. It has the Kwik-Switch motor mount with the 29, 38 and 54mm motor tube and the adapters for this. The fin-can has a pre-slotted Quantum tube. There is also the main lower body and the upper main body Quantum tubes. It also has the nose cone, 2 phenolic couplers (1 with parts for the bulkhead), the piston ejection system, and a very nice 60 inch parachute that is on par with the Rocketman chute's. The rear fins and forward canard fins are all G-10 and easy to work with.
The instructions are on one page and are very easy to follow. The subset instructions are for the Kwik-Switch and piston ejection system, the same one's that are included in any PML kit that has these features. The assembly order is good, although you must be very careful not to get any epoxy whatsoever in the grooves for the Kwik-Switch. This will be a bear to get out. This kit requires a lot of sanding before assembly, as recommended by PML, and I suggest you do it as instructed, prior to any assembly, it will make it all go quicker.
My phenolic couplers were exceptionally brittle, and were exceptionally tight, even with sanding. They did crack a little, and even though it was 60 degrees, I got a little concerned and decided to glass the inside of the couplers with 3 layers of 2 ounce glass cloth. I figured if anything, it will extend the life of the couplers, and is good practice.
I assembled the fin-can separately from the rest of the kit, due to the large size of the fillets needed both inside and out, and due to the power this kit can take. Some may decide to extend the pre-cut fin slots to the back of the tubing, and put the fins on the motor tube separately from the quantum tube. This way it is a breeze to fillet and glass the fins to the motor tube as PML suggests in their FAQ section of the website. The whole motor tube with the fins attached is then slid back into the the Quantum body tube, and the extended fin slots on the aft portion are wrapped with glass and sealed in when the surface fillets are done. I did not do this, but this is just a suggestion, it will beef up the kit.
I left the boattail off as I wanted to fly the kit and prove it before attaching it on there. I then mix my epoxy in medicine cups and poured it on the inside, making fillets along the motor mount and then to the inside of the Quantum tube. This is why you sand the quantum first, it is awfully hard to sand with that mount in there. One more modification I did was to epoxy some small 1/4 inch basswood nubs to the very aft end of the 29 and 38 mm Kwik-Switch mounts. This is to make it easier to turn the mounts when changing them. I also put 1 layer of glass on the tubes just to protect them, I am clumsy and may drop or kick them occasionally. It is a good idea to airfoil the G-10 fins as well. Not only will this help reduce drag, but it will eliminate some of the "flutter" you may get since these wings are so large. I used the tail portion of my Mouse sander and they are as sharp as a razor, they will cut you.
The one last change I made was to use some 1/4 inch bungee cord for the shock cord, and you can find the ferrules to clamp on the shock cord in a loop at Home Depot for $1.39, near the chain cutter. I did this because a few people have told me that the flat nylon that comes with the kit will act as a razor to cut stuff when it gets pulled taunt. On the first flight this did happen, and severed all but one of my parachute lines. A testament to the sturdiness is this kit fell from 4500 feet with only 1 chute cord barely attached and nothing broke. That is why you reinforce it so much, it protects your investment.
Finishing:
Pro-if you finish it good, this kit is an attention grabber, I used Dupli color auto paint from Wal-Mart for primer and finishing. You should use what works good for you. It is always humid here in Houston, so we are somewhat limited. You can use monokote for the stripes as suggested, it will work well. This kit is large, so it is a little different to paint than other kits. I painted it in sections, separate from one another to reduce over spray and the amount of tape needed.
Construction Rating: 4
Flight:
I was going to fly this on a J-350 first flight to level 2 on, but could not get one in time. I just brought it along to the launch. My friend had a J-570 he wanted to burn, but the RSO told him his 20LB rocket was too heavy. Well what better for a shake-down flight than a J-570? The wind was gusty at our trial launch at the new high power sight. There was an eerie hissing as the air pushed out of the rocket since we were loading the piston ejection after the motor was already in. The BBX screamed into the air, straight up. Unfortunately the chute lines were shredded by the shock cord (we felt) as soon as the kit ejected at apogee. The vacuum formed also blew off the lower main tube so the piston was stuck at the top of the lower main tube, and was connected to the fin-can by the piston strap. It came down from ~4500 feet, no damage though.
The piston got a good scrubbing and sanding after that, and a small vent hole was added towards the very top of the lower tube to help prevent the vacuum again.
Recovery:
Like I said before, go to a hardware or a store that sells the bungee cord and it will be cheap. I bought 10 foot for $4, add the ferrules and it comes to $5.50. Add a nylon rope for back up from Wal mart, and a new ejection system for $7.00. Pretty cheap, huh?
Flight Rating: 3
Summary:
Pro-Very strong, easy to build, easy to level 2 on. Large forward section for future electronics if you want. PML quality. Note-the Tomahawk and Mini BBX I purchased after this kit have sanded pistons direct from PML. Con-Piston requires lots of sanding for smooth fit, nylon shock cord should be changed to bungee.
Overall Rating: 4
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T. (February 1, 2001)