MMX Adapter

[JAL3]

I am considering ordering a package of the Fliskits MMX to BT5 motor mounts. I want to build an "adapter" that can be used when wanted and removed to allow normal 13mm flights. According to the picture, it looks like there are just 2 centering rings. The other adapters I have built had more (other sizes).

Does anyone have any advice as to how best to adapt the MMX mount into an adapter?

EDIT:

I took it upon myself to move this question to what seems like a better venue.
Sorry!

 

[CharlaineC]

you could take a standard 13mm knock out the clay sand it down inside till it was lighter and then glu the centering rings on the top and bottem with the mmx tube inside. or order mmx tubeing the outer d. of the 13mm caseing and use that instead of the caseing. micromiesor will be more of a help here

 

[Huge Blues]

Anything "extra" you add will result in a weight penalty with MicroMaxx rockets and directly effect the performance. I have a small fleet of BT-5 size rockets and would consider that the limit for body tube size with a single motor.

I built a down scaled BT-5 Micro Big Bertha and gave it my standard full finish treatment. I am in no danger of losing it when it flies.

The Flis motor mounts are awesome BTW.

 

[gpoehlein]

You could always make your own centering rings from paper. That way, you could make two or three (3 if you want to build a standard Estes type adapter) rings that will slide better than a flat ring will.

To make a ring to adapt a T-2.5 to a BT-5, start with a piece of scrap T-2.5 to use as a mandrel. You will need a sheet of 20 lb printer paper (do NOT use 24# - these measurements depend on the right weight paper). Cut two 14" strips (full length) and one 4" strip. Width depends on how wide you need the ring to be. For standard rings I make them 2mm wide, but for an adapter you might want the aft one a bit wider. (If you want to use letter size paper, you will need two 11" strips and one 10" strip.)

Mix a bit of Elmers white glue with water - about 50/50 is right. Start the first wrap around the mandrel and tack with a bit of glue - be careful that you don't glue the paper to the mandrel. Paint the inside of the paper strip, about 4-5 inches at a time with the thinned glue and wrap it tightly. When you finish with the first strip, start the second right where the first ends - no overlap or gap. Repeat with the third strip. When done, move the ring on the mandrel to make sure it hasn't gotten glued in place and let dry. Or, if you are careful, you can go ahead and remove the ring from the mandrel and let dry - just be careful you don't deform it when you take it off the mandrel. Once dry, you can treat it just like you would treat an Estes paper centering ring/motor block. If needed, you can sand it a bit.

 

[jflis]

The easiest would be to get a 1.75" length of BT-2.5 tubing and add a third ring. I drew up a figure of this to better show what I mean.

We sell the tubes and the rings. Also, fwiw, in the single motor engine mount kits you get THREE mounts, so a total of 6 rings in there. To get started you'd only need some extra tubing to cut to size.

YOu assemble the mount such that one ring is flush with the top end of the tube. A second ring is about 3/8" from the other end (assuming your rocket is designed to have the motor stick out 1/4"). This forces that ring to be recessed 1/8" inside the tube. Come to think of it, that center ring may not even be needed or desired. In the figure I kept the Kevlar there as you actually could use this for your recovery device, if you wanted. That or just omit it.

Hope this helps!
jim

 

[JRThro]

Jim,

Do you use a motor block with MMX motors, or just tape the aft end to the motor tube?

 

[graylensman]

for my part, I use a motor block. A great source for motor blocks are expended mmx motors- a quick cut with my dremel tool, and presto! I've also used segments of T2 tubing.

 

[JAL3]

Thanks everyone for the info. It is much appreciated.

I have some light, Mosquito sized rockets I hardly ever fly because they usually get lost the first flight even on a 1/4A. I've been thinking about using MMX to make them "flyable without losing".

 

[MarkII]

The Micromaxx engine blocks that FlisKits sell are REAL nice, though. A short piece of BT-2 works, but I like to use the EB-2.5's.

Also the CR-2.5-5 centering rings, being laser-cut, fit absolutely perfectly into a BT-5. I think that their precision justifies purchasing them over making your own (unless you happen to have a laser cutter, too); I prefer them to any that I have made myself, and I'm a notorious cheapskate! If you really want to use DIY centering rings, cut thin (like 1/16" wide) strips of cardstock, coat them with glue, and wind them around the engine tube until you reach the desired thickness.

I have built adapters the way that Jim describes, but used only two rings, not three. The mass and thrust of the MMX-II engine do not require adding a third ring to stabilize and secure the engine tube.

MarkII

 

[jflis]

Jim,

Do you use a motor block with MMX motors, or just tape the aft end to the motor tube?

I use a motor block. More often than not I put the motor in and secure with tape before putting the igniter in. Too many times, in models without engine blocks, I would push in the toothpick to hole the igniter only to have the motor slide deep into the tube... frustrating as all gitout... LOL

 

[Peartree]

I am a do-it-yourself-to-save-a-buck kind of a guy (I'm cheap) and I have tried (successfully) to make my own MMX CRs from papered balsa. MAJOR pain in the kiester. After all the time and frustration, I invested in Mr. Flis' lazer cut versions. I've proven to myself that I can do it, it just isn't worth it (for me).

 

[JAL3]

Here's an additional question.

I've only used adapters in the past sparingly. When I've gone from 38mm to 29mm there has been no problem putting on tape for a friction fit. When I've gone from 24mm to 18mm, the engien hooks have kept the adapter in. When I've put a gone from 18mm to 13mm, it has always been on a minimum diameter rocket without an engine hook and the mount has usually been ejected instead of the chute. I can't get enough tape on it to get a good friction fit and still be able to get it into the receiver mount. I assume I would have a similar problem with 13mm to 6mm.

Is there a trick to this?

 

[gpoehlein]

Try taping the rear of the engine to the rear of the rocket. If you can't go all the way around the base of the rocket because the fins are even with the back edge, use three shorter strips of tape. The best tape I've found for taping motors to the back of the rocket is Tamiya masking tape - it comes on small widths (1/4" among others) but it holds a lot better than regular masking tape.

If nothing else, you should be able to wrap the tape around the back of the adapter. I've very seldom had this tape fail and kick the motor - I've been using this stuff for several regional contests now.

 

[JAL3]

Try taping the rear of the engine to the rear of the rocket. If you can't go all the way around the base of the rocket because the fins are even with the back edge, use three shorter strips of tape. The best tape I've found for taping motors to the back of the rocket is Tamiya masking tape - it comes on small widths (1/4" among others) but it holds a lot better than regular masking tape.

If nothing else, you should be able to wrap the tape around the back of the adapter. I've very seldom had this tape fail and kick the motor - I've been using this stuff for several regional contests now.

Thanks for the tip.

I do have some Tamiya tape around here someplace.

I have NEVER had a motor kicked on a friction fit until I tried the 13mm adapter. Then again, I also have an 24mm adapter that I have been trying to get out of a 29mm mount for about 6 months now too. TOO MUCH FRICTION!

 

[JAL3]

I'm seeking some clarification.

24mm: BT50
18mm: BT20
13mm: BT5
6mm: Is it BT2 or BT2.5?

 

[Micromeister]

T2 = .246" od (used as motor blocks)
T-2+ = .281" od (Minimum dia. Motor and Micro body tubes)
MicroMaxx-II motor casings = .253" OD +/- depending on batch

6mm = .2363" Nothing micromaxx is ACTUALLY 6mm. close but no bananna!

 

[jflis]

Here's an additional question.

I've only used adapters in the past sparingly. When I've gone from 38mm to 29mm there has been no problem putting on tape for a friction fit. When I've gone from 24mm to 18mm, the engien hooks have kept the adapter in. When I've put a gone from 18mm to 13mm, it has always been on a minimum diameter rocket without an engine hook and the mount has usually been ejected instead of the chute. I can't get enough tape on it to get a good friction fit and still be able to get it into the receiver mount. I assume I would have a similar problem with 13mm to 6mm.

Is there a trick to this?

For the 6mm/13mm adapter concept I mentioned earlier here's what I would do:

• Design the adapter such that the rearward ring of the adapter is recessed into the motor tube about 1/8" when installed.
• Wrap the tail end of the model (assuming minimum diameter) with masking tape that overhangs the end of the tube by 1/8"
• Fold this overhanging tape over to the inside of the motor tube making a reverse engine block to block the adapter from ejecting.

Have never tried this but seems like it would work just fine...

 

[gpoehlein]

I'm seeking some clarification.

24mm: BT50
18mm: BT20
13mm: BT5
6mm: Is it BT2 or BT2.5?

Minimum diameter micromaxx tubing from FlisKits is BT-2.5

 

[JAL3]

T2 = .246" od (used as motor blocks)
T-2+ = .281" od (Minimum dia. Motor and Micro body tubes)
MicroMaxx-II motor casings = .253" OD +/- depending on batch

6mm = .2363" Nothing micromaxx is ACTUALLY 6mm. close but no bananna!

That helps. THanks.

 

[JAL3]

For the 6mm/13mm adapter concept I mentioned earlier here's what I would do:

• Design the adapter such that the rearward ring of the adapter is recessed into the motor tube about 1/8" when installed.
• Wrap the tail end of the model (assuming minimum diameter) with masking tape that overhangs the end of the tube by 1/8"
• Fold this overhanging tape over to the inside of the motor tube making a reverse engine block to block the adapter from ejecting.

Have never tried this but seems like it would work just fine...

This makes sense too. Now all that I have to do is coerce my 24mm fingers into those itty bitty spaces.

 

[JAL3]

Minimum diameter micromaxx tubing from FlisKits is BT-2.5

Thanks to you as well. I do appreciate the response.

I have several MMX kits sitting around unopened. This is going to be my first venture past the Quest plastic thingumbobs.

 

[JAL3]

For the 6mm/13mm adapter concept I mentioned earlier here's what I would do:

• Design the adapter such that the rearward ring of the adapter is recessed into the motor tube about 1/8" when installed.
• Wrap the tail end of the model (assuming minimum diameter) with masking tape that overhangs the end of the tube by 1/8"
• Fold this overhanging tape over to the inside of the motor tube making a reverse engine block to block the adapter from ejecting.

Have never tried this but seems like it would work just fine...

I've put together the order and it will be mailed on Monday.
It seemed like such a shame for you to waste all that shipping box space on just a few MMX items so I took the opportunity to order the few remaining parts of the FlisFleet that I am missing.

Its a good thing that I can run faster than SHE WHO MUST BE OBEYED!

 

[jflis]

This makes sense too. Now all that I have to do is coerce my 24mm fingers into those itty bitty spaces.

That's what toothpicks and hemostats are for... (says he of fat fingers...)

 

[jflis]

Thanks to you as well. I do appreciate the response.

I have several MMX kits sitting around unopened. This is going to be my first venture past the Quest plastic thingumbobs.

Oh, to heck with the thingumbobs, you gotta get a doo Hickey

 

[gpoehlein]

Thanks to you as well. I do appreciate the response.

I have several MMX kits sitting around unopened. This is going to be my first venture past the Quest plastic thingumbobs.

You are quite welcome. BTW, I'll try to post my BT-5 rocket wraps/instructions for the downscale Alpha, Der Red Max and Cherokee D in the next couple of days - they are a lot of fun as well on MMX power.

Also BTW - the proper terminology for those Quest RTF MMX rockets are LPBs (for Little Plastic Bricks! )

 

[brianc]

BTW, I'll try to post my BT-5 rocket wraps/instructions for the downscale Alpha, Der Red Max and Cherokee D in the next couple of days - they are a lot of fun as well on MMX power.

Ah yes! The venerable BT-5 Downscale of classic rockets thread!
We really need to revive that one. (Start a new thread)

 

[JAL3]

Oh, to heck with the thingumbobs, you gotta get a doo Hickey

Its sitting in the build pile. In fact, I have all of the Fliskits MMX rockets sitting around waiting. I've been put off on actually doing anything by my intimidation of the small and the "out of site; out of mind" phenomenon. When I go to get a new project, these thing just don't jump out at me the way some bigger things do.

Still, its mostly the intimidation. I packed up my dissecting microscope back in 1988 or therabouts and don't know where I stored it.

 

[JAL3]

You are quite welcome. BTW, I'll try to post my BT-5 rocket wraps/instructions for the downscale Alpha, Der Red Max and Cherokee D in the next couple of days - they are a lot of fun as well on MMX power.

Also BTW - the proper terminology for those Quest RTF MMX rockets are LPBs (for Little Plastic Bricks! )

I'd heard the LPB refference before. Mine are even sitting in a box labeled" Quest Plastic Bricks". I just never seem to get around to doing anything with them.

I look forward to seeing the plans.

 

[BobH48]

Ah yes! The venerable BT-5 Downscale of classic rockets thread!

That was a great thread. It's really a shame that it's gone. Lucky for me that I downloaded Greg's wraps before the old TRF went down.