3x MMX Cluster Flis Stinger build Thread

By golly it worked Igor!
Over the weekend I converted a Flis MMX Stinger into a 3 motor clustered Stinger.
About the only real trouble I ran into was adding the outboard motor tubing changed the angle of the rear bulkhead a bit which required a little addition to the folded cardstock shroud. The total mass added including the bits of shroud overlay amounted to .5g which I'll add in nose weight when I swing test the model in the next day for so.
I have the unpainted Build photos downloaded from the camera but haven't labled or resized them as yet. will add them ASAP.

Edit:
busy morning..one pic is all I've had a chance to process, more later.
Edit:
another before sanding pic

Oh, THIS is going to be interesting... Can't wait for finishing pix and a flight report!

Have just barely gotten the model into the first 3 coats of grey primer Jim: I don't expect to have any finishing pics for awhile as other commitments will be occupying my time for the next week or so.

Ok finished up resizing and editing all the base construction pics for this little jewel anyway?

We can go back and look at most of the construction steps along the way.

First few pics are the Kit, packaging and micro parts. How Cool is it that we can get complete model rocket kits in a zip-lock baggie these days LOL!!!!

One of the orignal thoughts was to vent the two outboard boosters into the core but space being so tight it was simply quicker & easier to plug the booster motor tubes with a balsa nose block. I ended up using only 1/2 of a standard Flis Balsa nose block for both booster tubes saving the other half for another project. Each tube is 1-1/16" long.

Starting with the core motor mount.

I have to again bring attention to the absolute fantastic fit of ALL the micro to the Maxx components Fliskits is offering. From the very first individual pieces and kit after kit. I've been super impressed with the quality and attention to detail of each and every porduct i've personally purchased. HAT's Off again for the EXCELLENT fit of all rings and blocks. Suberb stuff!

You'll note i'm using both good old Elmer's white glue and Titebond-II on this build. Actually its an old Titebond-II bottle refilled with Elemer's Yellow carpenters glue LOL...but who's counting

While the rings set up I take the opportunity to punch out the laser cut 1/32" basswood standoff, rough up the OD of the clear Flis Launch lug..Sure makes them easier to see as well. and attach with yellow glue. careful alignment with a pair of tweezers sure help on this small assembly.

Gluing in the tiny laser cut motor block using a double glue joint method helps this rather thin piece do it's job a bit better. I've had a few of these blocks blown completely out of the motor tube by the MMX-II ejection charges if they are not really securely glued and forward fillet applied during installation.
I like to use a toothpick to add a generous forward fillet to these motor stops to help hold them in place.
My normal motor stops are a 3/16" long piece of T2 (.246") tubing which gives a good bit more surface area for attachment.

Two in-line booster tubes are 1-1/16" lengths of T2+ (.281") tubing with a bit of Flis Balsa nose block yellow glue installed giving a motor projection of 1/8" before inserting the block in the forward end of the tube the end is sealed with a couple coats of yellow glue to help fend off the ejection heat and flame. By adding this little extra barrier the plug usually outlasts the tube wall.

After both plugs have been set using a spent motor casing to check the depth the booster mounts are set aside to dry with an additional layer of yellow glue added to the outside forward end just because.

Since we are not venting these booster tubes the casing will be ejected at burn thur. this means only a tiny bit of masking tape will be needed to hold the motor in the tube while sitting on the pad.

I always replace the very thin kevlar with 30" of 90lb kevlar in all my Micro builds.

Once the centering rings glue has dried a round needle file is used to cut a groove in the forward ring to pass the line the two half hitches are used to tie the line around the mmt. after passing the line back out through the rear of the motor tube a bit of glue is used to restrain the loose ends reducing the knot to about the thickness of the centering ring making MMT installation a breeze.

Now we start getting to the fun parts.

Laying out the holes in the aft bulkhead for the inline booster tube. I used a T2+-T3 center ring to postion the outboard T2+ tubes. Since were cutting the openings with a dremel the wall thickness of the T3 is guestimated.

While we're looking at the 1/16" basswood sheet we can also remove the thickness of each of the booster tubes (.281") note we added the overhang line to attempt to get the fins in about the same postions on the outer tubes.

Using my altered Estes tube marking fixture carefully mark and extend the wing lines as well as LL line.

with a couple pieces of plate glass extend the marks the length of the tubes. also mark both side of the booster tubes for attachment fins a little later.

Because of the offset some sort of support needs to be place under the booster tube(s) to hold them in alignment with the core tube. for this particular attachment I needed .047" spacers. a handy scrap of basswood measured .045 and adding a thickness of paper came out on the money.

Once both tube initial attachments were set heavy yellow glue fillets were added to keep these tubes permanently in place.

after allowing the booster tube fillets to set up. both wing/fins are attached with yellow glue. here small yellow glue fillets are applied with finger to keep them as small a radius as possible.

Our altered rear bulkhead halfs are installed glued fillet filled. the assembly is set aside up side down to dry. while the body shroud is carefully cutout and white glue assembled.

the booster tubes that extend beyond the bulkhead with be trimmed off after the shroud is applied.

Sliding the prepared shroud into place we find the booster tubes have altered the bulkhead angle a bit. I considered cutting another new shroud but figuererd it would be another interesting detail if I layed out and added an overlay of cardstock to cover the unsightly mess

Some scrap Cardstock worked perfectly. after gluing in place a quick rub with Medium CA helped seal the connection edges and smooth the transition.

Once the shroud and it's connections were dry enough for handling the LL and standoff were installed.

While the shroud and LL mount were drying it was time to assemble the teeny tiny forward gun mounts for the 1/32" basswood sheet and strip.
These little details are so darn kewl Jim! great looking addition.
I was a little concerned when I build the first Stinger that the barrels wouldn't last through the first flight.. but they are a lot stronger then they appear.
While transporting this model down the the paint chamber I was carrying it and two other models with the guns mounts getting much of the load. All ended up very well

All the added materials, tubes and cardstock added .5grams to the overall weight of the model. I'm sure i've added some additional weight to the rear in extra glue as will so this mass plus one motor mass (1.1g) will be added as noseweight when I swing test the model shortly. To that end I hollowed out the Nosecone and added a Kevlar loop for attaching the shockline later. Then adding the fintip plates and fillets.

Last was to trim off the access overhand from the shroud extensions and booster motor tubes. then a little sanding to smooth out the look.
Back the the original pic #27b ready for primer and paint.

Now, THIS is a build thread Very cool modification there!

This is sweet, Micro!

Can't wait to see it finished.

An inspiration as usual.

Dying to know how it flies, and show us the cluster prep please when you do.

But MOST important of all......hope you get the little speed demon back!

Thanks Kindly Guys:
I'll be doing a little work on it this weekend. Hope to have the Clustered Stinger ready for the May Club launch. We'll see.

Blackjack, I'll make a special effort to photo document the cluster motor preperation and launch pad set-up. Nothing really special other then the use of a little "Range Box Relay" that I've posted the plans and specs for a bunch of times.

I truely believe success in clustering is all in the details. That is extra examination of every aspect of pre-launch igniter installation, and model set-up on the pad. Check the continuity of your igniters before, and after insertion as again after hook-up to the relay clips.
I kind of excited to see this one fly as well. I'm also hoping to control myself long enough to get the paint job done LOL.

Just a little update:
sorry pics are still in the camera, model has been Primed and sanded twice. Base coated in White. Then I decided the Copper metallic "Accent color" would be shot first and masked out with liquid masking after the paint has completely dried. Because both the metallics copper and 7172 Silver have better brilliance over a Black base coat the model was sanded off a bit and re-basecoated in Midnight black Rustoleum which has a copper base flake as well. It was so Perdy in Midnight black I almost didn't apply the Copper Metallic. At present it looks kind of funny since the copper doesn't cover the entire model. Masking should go on at some point this weekend, than knifed, tweezer peeled and shot with Silver Metallic Flake. With a club meeting and other stuff going on this weekend it's gonna be a busy couple days.

Got most of the finishing Pics out of the camera last evening.

Lazy me no filling anything, with anything other then cheapy Wal-mart grey primer. This Nosecone has some pretty deep grain but I decided to would be a good test bed for the wal-mart stuff. Sparyed on 3 wet coats then allowed all three to set of a day. Started sanding with 240, and finished up with 360grit.

Needed one more coat of Primer to fill the NC grain, then sparyed Krylon Gloss white base coat. Looked pretty good.

It was about this time I remembered Metallics have a higher brilliance if applied over a black base. Well NUTs, This should be good, Rustoleum Lacquer over Old formula Krylon. It tried to lift but thin coats allowed the Midnight black to be applied and dried to a fairly smooth basecoat.

Next color is Rustoleum Copper Metallic sparyed sparingly over the "accent areas" only and allowed to dry the full 30 minutes. These Rustoleum Metallic Flake Paints are GREAT, dry to the touch in 10minutes Fully cured in 30 minutes.

Working with a Sign masking product called Gripmask (normally a sprayed on masking) I brushed on several coats to get what I hoped would dry down to about a 3mil film. This mask applied over all the areas I want to remain copper metallic.

Over night the mask did its job drying to a bluish transparent film ready for hand knifing in the detail area. With Tweezers and knife tip all the excess mask was removed, ready for the 7172 Rustoleum Silver Metallic Flake top coats.

As luck would have it. I was able to get two good coats of Rustoleum Silver Metallic Flake on the model first thing Saturday morning giving it plenty of drying time before noon to Tweeze & knife point remove the remaining cover mask.

As part of a Finishing demonstration for the club meeting, this model fell right in.
Wet sanding to knock down the bit of paint dam between the two metallic flake colors would be a good point to start the wet sanding discussion.
Using a Ultra fine grey scotchbrite pad and plenty of water, I carefully wet sanded the high spots down. I did get a little over agressive in one fine area that now needs a tiny brush touch-up of Copper metallic before the decals can be applied.

Here are the last two Pre-Decal Pics of the left and right sides after wet sanding. Note that the gloss of the model has been reduced by this process. but fear not once the decals are dry a quick coat of Future will bring the High gloss back to both metallics.

Hopefully I'll have the future on and final pics taken this evening

Finished and Ready for Swing test and flying in a week or so at the next club Sport launch.

Oh, I am LOVING this Can't wait for a flight report! Great job, John, keep us posted.

Outstanding!!!

I love the way decals colors show up against the metallic silver.

Not to take away from your finishing, which is always flawless, but JF's decals are always the frosting on the cake for these tiny works of art. The downside is the tedious cutting/appling them as only micro fliers can know!

I hate to say it.... BUT if it were mine, after a successful flight and recovery....it just might become a hanger queen. LOL

You have shown us ''the love" on this project. I also am eagerly awaiting a flight report. Make sure there are PLENTY of eyes on this one and good luck!

Semper fly.

I'm glad you had the patience this time to do the two-tone. Very, very, cool!

Thanks guys:
I'm can't wait to get this one on the pad. should be a real Head snapper I'm thinkin LOL!!!

Ended up home sick over the weekend instead of going flying...What a DRAG!!! guess the new ones will have to wait til next month

Got to go fly some stuff this past weekend. Clustered Stinger was one of the few things I actually got off the ground due mainly to having my 1st born Daughter and two of the grand kids at the launch. We did more catching up the flying..my bad but it was so much fun having them there.

Back to the task at hand getting the 3 motor clustered Stinger on the pad and into the air.

I used a mixture of old Q2 pyrogen tipped igniters, Heavy lead and lighter lead. just to show they both can work in micro models with care.
The Heavier leads make inserting a bit more difficult as the crimped bridge wire is still 38ga (super thin) which can break easily after the glass ball has been removed. I find it works best to insert the pyrogen tip first then crush the glass ball with a pair of needle nose pliers, split the leads carefully inserting a tiny FP wadding ball between the leads into the nozzle with the tip of a bamboo stict or nut picker.. It ok to use a metal pointed prob just don't cause a spark once the PFwadding is packed in place cover with a piece of 1/8" masking tape. apply a bit more of the 1/8" masking tape to the outside of the casing and insert it firmly in the motor tube. use a second piece of 1/8" masking tape to surround the extended casing & motor tube making a firm, Tight Seal. Move on to the NE motors these don't require much friction tape or the outside taping as they are intended to kick-out if needed at burn through. Once the are in place carefully twist the core motor and one of the booster motor leads then roll into a tight roll for clip attachment. repeat on the second NE motor/core lead. Now finish the remaining outboard NE leads rolling each into a clip coil close to the nozzle. Remember when using a relay you should alway have an even number of clip leads regardless of the number of motors in the cluster. In this case 3 motors 4 lead attachment points.

Speaking of Relays:
I'm including a couple photos of my small 10amp Range Box Relay and a newly updated Drawing/diagram & parts list. If you have trouble reading any of the lettering drop me an e-mail I'll send you the higher res. version.

At the field we set up our Micro launch pad and attach or lay the range box relay under or beside the launcher with the Relay 12V power battery in close. I generally do a relay check before connection anything to the igniter leads just to ensure the Relay points are not fused and the contacts are clean and working properly before hooking anything up to the model.

When satisfied that our relay is working and the system is relay coil safe. meaning the continuity check current won't be enough to energize the relay coil. We hook up the leads to our DPDT relay alternating Pos & Neg. leads around the cluster. Our Red armed light should be lit when each pair of relay leads complete the circuit. This can then be double checked by removing one of the leads from one side of the cluster then then next as long as our red lamp remains on our continuity is good through the wiring and igniters.

Sounds complicated, it really isn't just take a little more time to get everything set. but it does really make a difference in success rate. Since switching to a Relay Ignition system back in the early 80's, flying litterally a couple thousand clustered models I've logged exactly 13 unlit motors in all that time 2 of which were motors in clusters that had no igniters in them at all for testing but have to be counted as the motors were installed

so here are the prep and Pre-flight pad photos of the clustered Stinger, 5..4..3..2..1..start...GONE! I hit the camera button at start and totally missed the entire flight. as you can see the better 2/3rds and daugher #1 had the model in sight out of frame just that quick! Wow was that a FAST one. the model apparently did a little wiggleing around after burn out as it didn't get nearly the altitude I expected, I'll add just a little more Nose weight before her next flight. but is was a pretty decent flight anyway, all three motor lit, deployed as expected and recovered undamaged.

Drat! hit the button before attaching the pics..sorry.

Very cool I love clusters, I don't care what size!

You said it didn't get as high as you would have expected. How high is that?

Jim:
By the time I caught up with the model is was already under streamer on the way down at about 55-60feet. The better 2/3rds said she thinks it did a tumble just before ejection but couldn't guess at the altitude, and I didn't catch up with the flight at all until vary late... I've gotta let someone else take the pics.

Remember... We know why Girls can't estimate distance and why it's our (mens) fault LOL!!!! Sorry can't finish that....