Here we go! LOC IRIS 3" build.

[Tyler P]

So, this is my first build of this magnitude. I'm currently flying Estes stuff and have experience up to E motors and have done a few of the more elaborate builds from them. I just finished the Rocketarium Black Brant IV, which is my first experience outside of Estes and also the first time seeing a baffle.

I received my kit from Pavel at www.allrockets.ca today and started checking it out. I really like how beefy the tubes are. Everything feels nice and solid and all the ply is nice. The actual build isn't going to be difficult and I plan on taking my time. This is not getting launched until next season.

Really, my only big question about this is what is the best way to protect the chute? I'd like to build a baffle if that will work. I was thinking of ordering up a length of 3" coupler and two 3" ply bulkheads and just drilling them out and installing it between the motor tube and payload section. Is this sufficient protection for an G or H motor, or should I be looking at putting some cooling mesh in the baffle? I'm not sure if that's common practice or if the baffle is fine on it's own.

Briefly, I toyed with doing something in the motor tube but sort of thought better of it. I have visions of the back pressure being too high and my motor exiting out the back without deployment of the chute, lol.

My intentions are to launch this on a G80 for first flight but I also plan to shoot for my L1 at some point next year, so I need it setup right.

Recommendations for good recovery practices are my biggest concern, so fire away. The build itself is pretty straight forward and I'm looking forward to digging in!

 

[Tyler P]

I forgot we had a "Recovery" section. Just took a quick peek and seems like my ideas have been thought of before. I'd like to hear from you high-power pro guys first before I checkout my order of parts, though.

 

[Tomflysrc]

I was considering a baffle recently, and came up with the one in the picture. However, it was overwhelmingly refuted by HPR guys, who ALL suggested I stick with Nomex protection.
I decided to listen to those who have “been there, done that”

 

[Nytrunner]

Check out any of Qquake's builds. He regularly uses baffle couplers in his zipper less high power rockets.

Some may tell you to "just use nomex", but if you want to experience building and applying a baffle, I encourage you to do so! It innterrupts the ejection particles while allowing the gas to pressurize the bay and eject. It also can be a sturdy shock cord mounting point.

Have fun!

 

[grouch]

I have used baffles and it's baffling why more people don't.

 

[Tyler P]

I was considering a baffle recently, and came up with the one in the picture. However, it was overwhelmingly refuted by HPR guys, who ALL suggested I stick with Nomex protection.
I decided to listen to those who have “been there, done that”

That looks like it would be effective.

I was thinking of doing a three bulkhead coupler. Outside holes, inside holes in middle, and then outside holes again. I figure that should be enough to make it work and cool things at the same time.

 

[Tyler P]

Check out any of Qquake's builds. He regularly uses baffle couplers in his zipper less high power rockets.

Some may tell you to "just use nomex", but if you want to experience building and applying a baffle, I encourage you to do so! It innterrupts the ejection particles while allowing the gas to pressurize the bay and eject. It also can be a sturdy shock cord mounting point.

Have fun!

I really like the idea of baffles. I'm not set yet, as I'd like to weigh all the options, but baffles are high on the list for sure.

 

[Tyler P]

I have used baffles and it's baffling why more people don't.

I haven't really seen any really good reasons not to use a baffle but I'm going to let everyone weigh in and choose from there.

People seem to complain about burning up their nomex and kevlar protection an awful lot. Maybe a baffle in conjunction with the nomex "wadding" would work better.

 

[grouch]

Baffles combined with a zipperless design makes for a convenient harness attachment point. Depending on how it's designed, there are a lot of benefits including easy shock cord replacement and inspection. I personally don't like gluing the shock cord to the motor mount because shock cords can and do get frayed. I like modular designs that give you access to wear parts.

BTW, the baffle you cut would work very well. I personally like the cold air design where the gasses have to change directions but there are many ways to make an effective baffle. Good stuff.

 

[DM1975]

I almost always build a baffle of some kind into my rockets. I don’t rely on it completely but that’s just me.

 

[Jozef]

I do not see a motor retainer in your parts pile. That would resolve your concern for ejecting the motor. Aero Pak retainers are nice and allow you to adapt smaller diameter motors for flexibility. Go ahead a build your baffle... you can add a 9 inch Nomex chute protector for insurance.

 

[Andrew_ASC]

You can go to an alpine butterfly knot and a quick link to attach/detach chutes easily on ground. Top flight recovery makes nice chutes on a budget they pack nicely. Otherwise fruity chute is a more higher end option but those don’t pack as nice. I prefer OneBadHawk recovery harnesses. He can make any size for you if you don’t like what he offers in Kevlar. Use plenty of shock cord up to 25 ft. I like keeping my L-1 rocket simple, motor eject, single deploy, and no electronics for first flight my opinion there. I’ve never flown a rocket with a baffle. Not a baffle hater just view it as different method.

 

[Andrew_ASC]

As you build your rocket you can measure and weigh all the components then insert into open rocket simulator to find CG and CP on rocket. Then you can virtually select an L-1 motor and see what motor delays are needed for apogee deployment should you chose that option. As far as motor retention everyone has masking tape lying around the house so friction fit is an option. Roll it on the casing ends and shove the motor in. You can’t get it out again without say a broom stick and a mini sledge then you know you’ve done it right.

 

[dr wogz]

Keep the chute, do away with the elastic. Make your shock cord at least 3x the rocket length.. I use a combination of Kevlar in the bottom, and parachute cord for the upper portion. Get a nomex blanket. They do burn out, but it does take time! Aeropack retainers! Get some rail buttons.

If you bought from Pavel, you much be a Canadian.. Toronto?

 

[kuririn]

Kudos to you for building your own baffle. Another benefit of a baffle is that it prevents the recovery laundry from sliding aft in the rocket, shifting the CG rearward. Just remember to glue the baffle as far forward as possible while still allowing sufficient room for the recovery gear. This will prevent the CG from moving back, potentially making the rocket unstable. As with any modification, double check for stability. Open Rocket and RocSim are good simming tools.

You mention the motor tube and a cooling mesh. Did you see this?

https://www.rocketarium.com/Build/Ejection-Baffles/Baffle-29

The Aerotech "Labyrinth" system uses a plastic baffle and cooling mesh in the motor tube. It does accumulate ejection debris after a few launches, but it is removable for cleaning, since it is not permanently glued in. Just use a long wire hook to remove it from the engine end and stretch it out and clean it, then reinstall. Comes standard in Aerotech kits.

For motor retention, there are a number of systems. The Estes plastic screw on motor retainer is cheap and effective. The metal screw on retainers are more expensive. There are also bolt on rings.

Masking tape is also effective and cheap. However instead of wrapping around the casing body and getting a tight fit that is hard to remove, most modelers now days wrap a strip around the aft end of the engine that acts as a rear thrust flange, then wrap a wider strip around the engine and motor tube, holding the motor in at ejection. I had doubts about this method when I first read about it. I thought that surely the ejection charge would blow the motor out of the tube with just the end wrapped. But it works. A swipe of thin CA around the end of the motor tube will prevent the tape from lifting the paper upon removal.

Most of all, remember to HAVE FUN!

 

[Nytrunner]

To provide the traditional TRF counterpoint; Keep the elastic! It works fine for this size rocket, doesn't zipper the tube as easily, and doesn't make you order something extra! (just fold a ducktape strip around the ~10" closest to the ejection charge).

 

[Wallace]

And keep the baffle idea too..

 

[Tyler P]

Keep the chute, do away with the elastic. Make your shock cord at least 3x the rocket length.. I use a combination of Kevlar in the bottom, and parachute cord for the upper portion. Get a nomex blanket. They do burn out, but it does take time! Aeropack retainers! Get some rail buttons.

If you bought from Pavel, you much be a Canadian.. Toronto?

I'm, indeed, going with a baffle, but I asked Pavel for his suggestion and I also ordered up a 12x12 nomex chute protector for added insurance. Going to do a 3" coupler baffle with 3 levels and use it for shock cord attachment as well. I'll order up the retainers when I figure out what motors I'm going with. It might actually end up just being a L1 instead of G motor, so won't need 29mm.

Rail buttons were ordered with the kit, I just forgot about the chute protection.

Indeed, I'm Canadian! Ottawa, though. Just about to get my family membership to CAR and possibly do my first club launch with the Ottawa Rocketry Group. I've been flying at local sports fields and my rc flying club over the last couple seasons, but I figure it's time to associated with those in the "know", if you know what I mean, lol.

 

[dr wogz]

Good people at ORG.

Ask Teresa or Bill if CAR is needed. If I recall, they are Tripoli..

High power at ORG is limited though.. ask.. G is OK, H or above is limited..

I'm in Montreal, and I fly out of Vermont, 12K' and we fly every month.

 

[Tyler P]

Kuririn, I did see that mesh holder setup but didn't see a 38mm option. I'm also thinking of going to the aluminum motor retainer, but will check out the options for my next order.

For those curious, I'll likely employ a JLCR. I really like the idea of setting the the altitude for deployment. Much less chance of a long drift and losing the rocket.

 

[Tyler P]

Good people at ORG.

Ask Teresa or Bill if CAR is needed. If I recall, they are Tripoli..

High power at ORG is limited though.. ask.. G is OK, H or above is limited..

I'm in Montreal, and I fly out of Vermont, 12K' and we fly every month.

Yup, I've met them both. Didn't realize they were Tripoli. I'll shoot Bill and email to confirm. I believe they're limited to 750 meters for H, if I remember correctly. I'll just be launching some low and mid-power up to E this time around. L1 will be next season.

Man, 12000'? That's awesome. My new ship is rated to 5800' with the biggest motor, lol. How far is the Vermont site and how is getting across the border with rocketry gear?

 

[Bat-mite]

Why not go full scale?

 

[Tyler P]

Why not go full scale?

That's so awesome!

My order of baffle parts and a chute protector have arrived, so I may start building tonight!

 

[Tyler P]

So I've started the build! I haven't officially done anything on the kit itself but I built the baffle which, I guess, is my first official mod, as well!

I ordered 3" coupler tube, bulkheads, and a 1/4" eyebolt.

The bottom holes are 1/4" with a 3/8" in the middle, and 8 exit holes are 3/8". I epoxied the plates in with BSI and also laid a nice fillet inside the shock cord retention end.

 

[Tyler P]

Put the motor tube together. I also installed a little block of ply to give me a better target for the lower rail button to screw into.

 

[Tyler P]

Rounded fin edges, sanded surfaces smooth with 400, and applied 3 or 4 coats of Deluxe Materials Eze-Kote finishing resin with a brush, sanding between coats. I'm going to let it cure up a bit, give it a final smooth sanding and then airbrush a final coat on.

I also test-fit my motor tube in the airframe and marked the center of my ply rail button tab and drew the alignment line.

One question I have is how far apart can the rail buttons be? The lower button won't be an issue to install because it has a wood anchor to screw into. The upper one, however, is going to be a bit of a trick unless I notch the upper centering ring for the button retainer so that I can preinstall it. Is a small flat side on the upper centering ring okay so I can slide it past the button retainer when I glue in the motor tube? Or can I install the upper retainer above the motor tube? It looks a little long to be mounting the button that far up, so I'm leaning towards option 1.

 

[Tyler P]

Actually, after dry-fitting the full length of tubes, the second button would only be about half-way up the rocket. Is that close enough together to support it until it gets to flying speed? That would be the preferrable mounting option, as I don't like the idea of the pressure getting down around the motor tube on chute deployment if I leave an opening.

 

[markg]

Actually, after dry-fitting the full length of tubes, the second button would only be about half-way up the rocket. Is that close enough together to support it until it gets to flying speed? That would be the preferrable mounting option, as I don't like the idea of the pressure getting down around the motor tube on chute deployment if I leave an opening.

Did you already glue that upper CR? I'd suggest cutting the MMT down to about half that length and moving the CR down with it. The MMT does not need to match the length of your longest motor, by leaving it long you are adding weight where you don't want it.

If it's already glued, putting the button above is higher than I would want it. I'd definitely put it lower. Maybe glue an extra block onto the MMT to screw into if you want a solid connection.

Also, I've used the same sort of baffle you built in a 2.6" rocket that I fly on 38mm motors and it works great. Cross the border next spring and come to NY Power, it's a great weekend of flying and a bunch of people from the Ottawa club always go there. I'm down the road from you in Windsor.

cheers - mark

 

[Nytrunner]

When the top button leaves the rail, the rocket can then yaw around the rear button.
If you subtract the distance between buttons from your rail length, and it's still getting up to sufficient speed, then you're good.

 

[Tyler P]

Did you already glue that upper CR? I'd suggest cutting the MMT down to about half that length and moving the CR down with it. The MMT does not need to match the length of your longest motor, by leaving it long you are adding weight where you don't want it.

If it's already glued, putting the button above is higher than I would want it. I'd definitely put it lower. Maybe glue an extra block onto the MMT to screw into if you want a solid connection.

Also, I've used the same sort of baffle you built in a 2.6" rocket that I fly on 38mm motors and it works great. Cross the border next spring and come to NY Power, it's a great weekend of flying and a bunch of people from the Ottawa club always go there. I'm down the road from you in Windsor.

cheers - mark

Thanks Mark. Yes, I've already glued the rings. It looked a bit higher than I thought it should be, as well.

Luckily, I ordered 2 of each type of button, so installing the upper one into a block mounted on the motor tube is probabaly what I'll do. That's the easiest fix and it'll be even a bit more solid than the other type.

I'd love to hit a couple US sites next year! That would be super fun. I'll definitely keep it in mind.