Mach 1 Mini Black Brant BT50 Build

[base890]

Excited for a robust little fiberglass model rocket I purchased a BT50 black brant kit from Mach 1.

 

[base890]

My only critique of the kit is the hole in the motor mount for the Estes-type motor retainer. The fiberglass fibers tore on the inside making seating a motor to the level of the hole difficult without repairing the inner part of the tubing. No big deal really. The retainer metal is far better quality than the ones that come with Estes kits.

 

[base890]

Since I plan to try for higher altitude with a D-24BT-7 re-loadable motor - I trimmed the tip off the retainer to accommodate the wider forward closure.

 

[base890]

However... when dry fitting the mount in the body tube I noticed the following problem. The body tube doesn't allow enough clearance to load a motor without considerable aft overhang.

 

[Nytrunner]

May want to trim that motor hook a tad.

I didn't know they made their FG kits for 18mm.....that's nuts

 

[base890]

The solution was to purchase a motor retainer (suggested by Mach 1).

 

[base890]

Another little hitch with the motor mount is not really trouble with the tube diameter so much as a complaint about the Q-Jet motors... the label wrap on the plastic makes the diameter too large to fit. Try to remove the label and you get into a sticky mess of tearing paper and glue. Tried some solvent on the goo and melted the casing!

Does anyone know a good way to remove these labels without affecting the plastic underneath?

 

[base890]

I don't have a rocket using a piston yet - so I thought I'd try one in this little rocket.

 

[base890]

The kit comes with a streamer, I think given the simulation speeds I might make it a small parachute instead.

 

[base890]

Prior to assembly - washed all parts well then wiped with acetone followed by sanding with 60 grit and scoring 1-2mm hatches with a scalpel blade. Put 10 degree tapers on the fins using a sanding jig then epoxied to body using a makeshift fin jig - one at a time.

 

[base890]

One all of them were anchored with rocketpoxy, pulled fillets using the ball stylus tools I learned about on these forums somewhere, they're pretty slick!

 

[NateB]

I have built a Mach 1 Exiter and Boost for 18mm motors. The Exiter came with that same streamer and came down a little fast, but safe. The Boost is a BT-50 and came with the same motor hook and an orange nylon streamer.

I regret building the Boost with the motor hook and thrust ring instead of a screw on retainer. I also think I will use a small parachute instead of the streamer unless the field is really soft. Part of me is tempted to buy another one and build it differently to fly mostly with the Aerotech 18mm case.

 

[swatkat]

I use a 9" nylon chute from Bama (now Rocketman) in my Exiter... perfect descents.

 

[lowga]

Building FG rockets for 18mm motor is the point. They're amazing kits, and super fun to fly. Thanks for posting this build thread.

 

[base890]

Finished construction. I made a thrust ring with JB weld and a reinforced cardboard ring given some flights will be in C6 engines. Rocketpoxy to stick the centering rings to the body tube, then the engine retainer with JB Weld.

 

[base890]

Made a shockcord protector from some nomex and a long wide streamer out of hot pink silnylon.

I took it out for a flight at the soccer field to get an idea of how the streamer would work.

I used a Quest B4-4 because it was kinda windy and it’s small area. Open rocket had it going to 250’ or so. Something must’ve happened with the motor. It took about 1s to pressurize, boosted of the pad fine but instead of 4s delay, the ejection charge didn’t go off until the rocket was in the ground 15s after liftoff. Nose cone got buried completely and when the charge went off the rest shot up out of the ground a good 30-40’, the steamer came out and then everything landed in a soccer net.
Other than the cheap plastic shockcord anchor on the nose cone breaking, no damage was found. This says a lot for the strength of this fiberglass!

Definitely earned some paint.

 

[base890]

Got some paint on...

Does anyone have any advice how to best place the vinyl decal - it’s in one big piece.

 

[base890]

Final weight and balance, now with 120”x4” streamer.

 

[crossfire]

Got some paint on...

Does anyone have any advice how to best place the vinyl decal - it’s in one big piece.

Check out Sticker Shock 23 web site they have videos on how to put wraps on. I did a 2.6 BB wrap and it went well.

 

[Nacho]

Final weight and balance, now with 120”x4” streamer. View attachment 372640View attachment 372641

That looks amazing! I already like it without the decals.

 

[base890]

I’m now working on getting the vinyl decal placed but am unsure of the best placement...

any ideas about where it should go? Red arrow reference on a fin root? Where do I put the thin lines (green arrow marks one)?

Thanks for the tips!

 

[crossfire]

I think when I did the 2.6 VB I cut the strip section and put them on separate from upper section decal. It worked out well for me.

 

[base890]

I think when I did the 2.6 VB I cut the strip section and put them on separate from upper section decal. It worked out well for me.

Where did the little green arrow stripes go? On the fins?

 

[crossfire]

Where did the little green arrow stripes go? On the fins?

I guess I don't recall the green arrow strips. I would guess they would be put along side the fin close to the fillets

 

[kuririn]

I think there should only be one "green stripe", and that is actually a slot for one of the fins to slip into. There are four white lower panels, and only three fins. so one fin rests one top one panel, and the other panels should fall in between the fins.
As far as application, using a spray bottle filled with water and a few drops of dish soap will allow you to move the decal around to the perfect position. On the Stickershock website, click on FAQs/How to's and scroll down to "How do I install my decal?" A couple of good videos there.

 

[kuririn]

Correction: The red arrow in your photo is the slot for the fin. And what color are the thin lines? If they are gray then they could be for the leading edges of the fins. I referred to Alway's Rockets of the World for the livery.

 

[crossfire]

What happened to me was the fin fillets were to wide for the slotted strip to work out.

 

[base890]

Thanks all. I went ahead and tried it, had to widen the fin slot a tad which despite a brand new scalpel blade still didn’t want to lay flat perfectly - but it’s good enough, eh? I left off the small pinstripes for now as I can’t find exactly where they should be going.

 

[base890]

Correction: The red arrow in your photo is the slot for the fin. And what color are the thin lines? If they are gray then they could be for the leading edges of the fins. I referred to Alway's Rockets of the World for the livery.

The thin lines are white but leading edge seems right for how they’re positioned on the backer- just I airfoiled mine to a knife edge so not going with that.

 

[Andrew_ASC]

Nice build.