# Mini BBX

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#### Chilly

##### Well-Known Member
I'm getting ready to start building one, and intend to fly it with the Terrier booster. Any ideas on motor retention? EMRR mentioned a slimline retainer. Would that fit inside the tailcone or will I need to leave 1/2" of tube hanging out?

Suppose I can go with tape but I'd rather not do that with an RMS casing. Not so worried about losing it, just beating the crap out of it when it's time to remove the thing.

#### Justin Horne

##### Well-Known Member
Off topic (kinda) but:
A tip I learned about friction fitting casings is to take the aft closure off, remove the nozzle, and put the closure back on. This lets you get a good grip when trying to pull the casing out.

As for motors, I think it would be neat on a I161 to a G75. G75's are great for second stage/airstartes in my opinion. That black smoke just looks good..

#### xenon

##### Well-Known Member
You might want to look at the Slimline tail cones. Though I'm not sure if it would keep the scale appearance of the BBX because I'm not realy framiliar with it.
You can get the tail cones at Giant Leap

#### loopy

##### Well-Known Member
Whatever you pick, you'll want to make sure it'll be compatible with the terrier booster. Might want to check with Andy at PML to see if he has any suggestions?

Loopy

#### thomasrau

##### Well-Known Member
Giant Leap's slime line retainer will work, both my MiniBBX and Terrier booster have them and everything fits great.

#### gerbs4me

##### Well-Known Member
I agree with Justin Horne on motor selection, the G75 is a cool motor

#### Ryan S.

##### Well-Known Member
cool but tough to light, I would go with something like a WL motor at least, Blue thunder would be the easiest to light but no very cool looking. YOu want a motor that comes up to pressure though, not something that chuffs until the rocket is sideways

#### Chilly

##### Well-Known Member
Originally posted by thomasrau
Giant Leap's slime line retainer will work, both my MiniBBX and Terrier booster have them and everything fits great.
That's what I was looking for! Did you have to trim out the BBX tailcone at all, or did the retainer still fit over the motor tube? Did you have to modify the stage coupler on the Terrier?

#### thomasrau

##### Well-Known Member
It fit perfectly, no extra trimming was needed. Just one word of caution, I would avoid G motors in the sustainer. The timer will not light regular ignitors, and dipped ematches are a tight fit in the slotted grain. Also stick with white lightning and blue thunder loads. This is especially important if its the non-CPR version, if the second stage doesn't light you lose the rocket.

#### Chilly

##### Well-Known Member
Thanks, White Lightning's my favorite propellant anyway.

I'm planning to use an H180 for the sustainer. I won't fly it staged without dual deployment. It's not being built with CPR but I am going to fashion my own altimeter bay...I plan to cut a 5" section out of the upper BT, and maybe use the piston coupler & bulkhead for the fwd end of the bay. Haven't decided if I want to keep the piston recovery or not.

I won't take on the booster until my L2 cert, either this fall or early spring. I want to use a 5 or 6 grain Pro38 for the booster.

#### thomasrau

##### Well-Known Member
Then you'll have to modify the Terrier as well, stock it will not take a 5 or 6 grain pro38, too short for that.

#### Ryan S.

##### Well-Known Member
A Cesaroni would be perfect for the sustainer, easy to light, comes with an ematch. And if you want you can use a smokey motor, that will look like a G75

#### Chilly

##### Well-Known Member
A Pro38 won't fit in the MiniBBX, it's made for 29mm.
The Terrier won't fit a 5-grain motor? Can it at least fit a 4-grain? I was hoping to put it up on a J but an I will do.

#### thomasrau

##### Well-Known Member
Originally posted by Ryan S.
A Cesaroni would be perfect for the sustainer, easy to light, comes with an ematch. And if you want you can use a smokey motor, that will look like a G75
Sadly the mini-BBX has a 29mm mount so a Pro38 is out of the question for the sustainer. But you are right, Cessaroni motors are absolutely the best choice for HP clusters and staging. The supplied ematches work with virtually all elecronics, and the ignition pellet insures a quick ignition. When I flew my Bruiser-EXP last season the Pro38 outboards came up to pressure within 1/20 seconds of each other.

#### thomasrau

##### Well-Known Member
Originally posted by Chilly
A Pro38 won't fit in the MiniBBX, it's made for 29mm.
The Terrier won't fit a 5-grain motor? Can it at least fit a 4-grain? I was hoping to put it up on a J but an I will do.
On mine a 4-Grain does fit. Just remember a stock Terrier booster uses motor ejection, put in a real big honkin motor and the terrier will drift out of sight.

#### Chilly

##### Well-Known Member
How much altitude do you get from the booster, and how long of a delay do you normally use for ejection? What about lighting the sustainer?

I really want to do this next winter as a way to get into electronics, and staging timers seem pretty simple.

My thinking is this combo is for "fun", when I'm ready for serious altitude it'll be time to get a Quantum Leap...

#### thomasrau

##### Well-Known Member
I typically fly it with the three grain I205 pro38 in the booster, that will take the terrier to around 1400-1500 feet with a 7 sec delay. The sustainer usually gets an H180W or H238T and that takes it to 3200 or 3900 feet. The 4 Grain I285 gets the Terrier to at least 2750 feet and needs a ten second delay. The only time I used the 4 grain I used a G80 in the sustainer to keep the altitude down (kinda windy) and the G80 CATO'd, blew the heck out of the front end of the terrier and flexed the quantum tubing enough on the sustainer that it blew the paint of and all the fin fillets. CPR saved the day and deployed things anyway.

#### thomasrau

##### Well-Known Member
Quantum Leap is a great kit, last time I looked my sustainer was still about 70-80 feet stretched between two trees in a swamp, but was a great flier, just didn't get the landing right that day. The booster was also up a tree but was close enough that the linesman pole could snag it. Dang tree's.....

#### LampertRocketry

##### Well-Known Member
It is indeed a 29mm motor mount. I asked around and even called PML to inquire. Not liking the answers I received and not knowing any better, I just drilled three holes around the tube, screwed in some threaded bushings (brass) and used thumbscrews to hold the motors in place. Works like a million bucks and cost a total of about $2 - well, actually, it cost me$25 as I went out and bought a whole box of threaded inserts and thumbscrews and I use them on everything I build now.

Regretably, I messed up (personal error - used the wrong e matches) and my BBX/CPR3K is sleeping with the corn, so I now have a Terrier booster complete with timer. If anyone is interested in purchasing same I will sell it, otherwise I am looking for a Mini BBX/CPR3K kit.

Murray Lampert

Originally posted by thomasrau
Sadly the mini-BBX has a 29mm mount so a Pro38 is out of the question for the sustainer. But you are right, Cessaroni motors are absolutely the best choice for HP clusters and staging. The supplied ematches work with virtually all elecronics, and the ignition pellet insures a quick ignition. When I flew my Bruiser-EXP last season the Pro38 outboards came up to pressure within 1/20 seconds of each other.

#### nichanderson

##### Well-Known Member
I've flown my PML Mini-BBx and scratch built Terrier Booster on a I284 to I200. Got about 9000' out of it. Was a cool flight.

As many others have noted, a slimline will fit into the tail cone with no mods, and works great for PMR.

If you can find someone in your area making thermite igniters, you can fly just about any motor you want, regardless of propellant type. People in industry use a Iron thermite reaction to weld railroad tracks together.. and now people are using this same reaction to light rocket motors. Works great.

Nick Anderson

#### Ryan S.

##### Well-Known Member
most use copper thermite though, you are right, it works great at will light about anything.

If you can get it into the nozzle

I have found it really only works in larger motors, they say a gram per 1000 NS, so when you have an I 200 there is very very little

#### Hospital_Rocket

##### Well-Known Member
My Mini-BBX flew for L1 on a Ellis H50-6. I fly it all the time on G-64, F-50, G-80.

I want to try an Ellis I-90 and a AT H165R

I did not plan on using the Terrier, so I used an Aeropack retainer. Works like a champ.

#### nichanderson

##### Well-Known Member
Originally posted by Ryan S.
most use copper thermite though, you are right, it works great at will light about anything.

If you can get it into the nozzle

I have found it really only works in larger motors, they say a gram per 1000 NS, so when you have an I 200 there is very very little
Yes, its best when its built into the motor before assembly, and use a drinking straw to contain the powder and a ematch for the actual ignition source.

Nick Anderson

#### FredT

##### Well-Known Member
Chilly-

Just to reiterate what Tom said. A slimline retainer on the sustainer does fit into the tailcone and into the Terrier booster. However, the Terrier comes with a phenolic liner that sides inside its stage coupler toprotect against upper stage motor exhaust. This didn't fit with the slimline. I substituted a collar made of aluminum roof flashing material.

I've had seven two-stage flights; all with successful upper stage ignition.

I recommend replacing the booster's 3/8 in. launch lug with rail guides. The rocket is fairly heavy (in two-stage configuration). Rod whip is a real issue. You really want vertical lift-off (and staging).

An I357-M is the best choice for the booster. It gets you off the pad fast and straight. (Someday I'd like to try an I300.) I've used anything from G40 to H180's in the upper stage. My last flight was with a H210R up top. The red flame at staging was impressive!

Through experience I've found it is best to set the AccuFire for zero delay. Even so, there is at least at 1/2 second delay between booster burnout and upper stage ignition (as recorded by the onboard AltAcc).

...Fred

#### thomasrau

##### Well-Known Member
Fred,

Good point, thanks I had forgotten all about the liner, on mine I just trimmed it a bit (had to shorten it) until it fit then coated the inside of the liner with a good layer of epoxy.

#### Chilly

##### Well-Known Member
That's what I was wondering. I figured on just sanding down the coupler liner to fit.
Good point about the rail guides. I was wondering about whether or not to do that also. Gotta go pick up some reloads from Ross soon, I'll add conformal rail guides to the list!

#### DPatell

##### Well-Known Member
If you want a little more forgiving rail buttons, go to www.railbuttons.com . The conformal guides are harder to line up, and rip off a lot easier than the railbutton.com ones do, mainly because they are screwed in. If you are using the piston, I think you will still be okay if you place the buttons at the top of the fin can tube, as well as at the base.

Looking forward to pics

#### thomasrau

##### Well-Known Member
On something as light as the Mini-BBX the conformal guides work well, just more expensive than a button. I never had one come off except for the time the sustainer motor cato'd, blew off the guides along with paint and fillets. On bigger, heavier rockets I agree, buttons are the way to go, far more forgiving.

#### Ryan S.

##### Well-Known Member
Originally posted by nichanderson
Yes, its best when its built into the motor before assembly, and use a drinking straw to contain the powder and a ematch for the actual ignition source.

Nick Anderson
I dont mean to go on about this, but I would be very careful about loadingit in the motor before I get on the pad, it doesnt take much to light an ematch

#### lalligood

##### Well-Known Member
Originally posted by DPatell
If you want a little more forgiving rail buttons, go to www.railbuttons.com . The conformal guides are harder to line up, and rip off a lot easier than the railbutton.com ones do, mainly because they are screwed in. If you are using the piston, I think you will still be okay if you place the buttons at the top of the fin can tube, as well as at the base.

Looking forward to pics
If you choose to go with the buttons from railbuttons.com, there is at least one way that you can attach them & not affect the piston. Take a look at this page on railbuttons.com and the review of my PML Phobos on EMRR. Both of these show how to surface mount rail buttons for the situation you are in.

Rail buttons ROCK!

HTH,