LOC Jet Fighter - Custom project for LDRS 37

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Mr G

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Thirsty did it.

He goaded me to share my fantasy of taking a 5.5" LOC Precision Big Nuke and turning into a jet fighter. And he even put a deadline on it - LDRS 37. So off I go into the Wild Blue notching it up with larger diameter, larger 54mm motor, asymmetrical protrusions, and who knows what else. Let's just hope that the final product is anywhere close to flyable by the middle of May.

After playing with Open Rocket, it became apparent that with some relatively minor modifications, a wing and canopy could be added to give the rocket a different look. What was not clear at the beginning was how much the innards would have to change. After many hours of adjusting for CG vs. CP and the mechanics of dual deploy, a design firmed up that required some extra parts.

Nat at UpscaleCNC was called into action to provide the needed pieces that were necessary for the transition.
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I would like to see how this turns out. How big of an engine do you intend on going with this? Always wanted to make a jet rocket that actually breaks the sound barrier. Would think it would need some serious reinforcing to prevent it disintegrating.


[video=youtube;-YaUgn72o3Q]https://www.youtube.com/watch?v=-YaUgn72o3Q[/video]
 
Thirsty did it.

He goaded me to share my fantasy of taking a 5.5" LOC Precision Big Nuke and turning into a jet fighter. And he even put a deadline on it - LDRS 37.

My plan worked!

But if you think I’m a bad enabler, wait until the rest of these guys get started...

This looks like a very cool project. I’m intrigued by the pile of custom parts you have there and can’t wait to see how they all go together!
 
This is going to be a BFR with enough drag between the addition of wings and being 5.5" in diameter to keep it subsonic regardless of 54mm motor size. And its cardboard. And it'll be heavy for its size. And it will look cool with smokey and sparky motors that don't have as much thrust.
 
This is going to be a BFR with enough drag between the addition of wings and being 5.5" in diameter to keep it subsonic regardless of 54mm motor size. And its cardboard. And it'll be heavy for its size. And it will look cool with smokey and sparky motors that don't have as much thrust.

That’s my kind of rocket.
 
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First task was shaping the canopy that will be attached to the nosecone. Two part foam was added to the inside of the plastic canopy to provide rigidity and a good gluing surface. Next a piece of 80 grit sandpaper was held down on the nosecone and the canopy pushed back and forth on the sandpaper until the foam matched the curvature of the nosecone.

Any suggestion on the best glue to bond the foam to the nosecone?
 
The Loc nose cone are made from [FONT=&amp]polypropolene, a low energy plastic and is notoriously difficult for good adhesion. Look at how water beads on the surface and imagine what that means for glue. Best surface preparation techniques include 80 grit sand paper, alcohol wiping, a flame treatment. Here is something I read when I researched the topic: [/FONT]https://multimedia.3m.com/mws/media...bonding-to-low-surface-energy-white-paper.pdf

Given this it is no surprise the common practice when adding nose weight to these nose cones includes the addition of dowels for mechanical retention beyond just using adhesive.

Have you considered adding dowles to penetrate both surfaces?
 
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Flying asymmetrical airplane rockets is crazy, but I like it! That canopy is looking F-15ish to me. Always nice that the canopy's up front so can be nice and heavy. Power and nose weight are your friends. Landing gear down and missiles attached can also help out in equalizing drag and they look really cool. Just finished another Estes Screaming Eagle and I am going again with the Israeli AF camouflage scheme, looks are everything. Those little kits just love the composite D motors. Yours will be much bigger.

Definitely keep that nose weight in check - a real problem with the early Mad Cow BOMARCs from the stories I have heard. They now have nose weight anchoring as a must in the instructions - dowels, screws, what ever it takes. All cardboard is an intriguing statement. Thristy is a good influence.

Hopefully your RSO is more forgiving - like Darth Vader!
 
There will be at least a pound of shot in the nosecone tip based on Open Rocket CG vs CP calculations and the plan for at least one caliber difference with the largest motor. This also allows a threaded rod to be inserted that will help hold all the pieces together in the nose cone including a dual deploy altimeter and tracker.

The non-symmetrical additions are a bit worrisome. But there are a bunch of designs like that and it is rare to hear a concern about the flight characteristics. Think of the 1:18 scale F-104C kit from Sheri's Hot Rockets as an example.

Any insight would be welcome.
 
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Here is a shot of of the "wings" and how they will attach through the 5.5" booster tube. The smaller inner diameter centering ring will fit the top of the 54mm motor mount. The larger one is 3" for the 14.5 inch cavity where the drogue chute will rest inside a tube that splits between the booster and payload areas. The forward end of the wings are just short of the break between the two tubes.
 
Snipped the tip of all three fins and then reshaped two to look more like "horizontal stabilizers." Think F-4 Phantom style.
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A 3.1" tube will anchor the wings internally. This greatly limits the usable space for the drogue chute and shock cord. Two 1/4" U-brackets just barely fit between the 54mm motor mount and inner wall of the drogue bay tube. IMG_1434.jpg

Support brackets had to be cut to match the outer wall of the motor mount.
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The drogue chute cavity is 9"x3". The rocket will weigh roughly 16 lbs at apogee. There appears to be enough space for 25' of 1/4" Kevlar and maybe...maybe an 18" inch drogue chute. Is this reasonable? Should it just come down drogue-less? Or will the descent speed be too high for main opening with an 84" Top Flight chute?
 
I don’t want to scare you. But the recovery of an Estes Conquest (It had wings too) anyways it glides horizontally after boost as the chute pops out at Apogee. Flight part is up then arcs weird. Can’t imagine how your recovery will look trying to chunk a drogue out too.
 
Gets as big a drogue as you can fit in it, a thin mill 24" or 36" may fit in about the same space as a heavier 18" chute. Interesting project so far.
 
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Gluing the internal components with the wings dry fitted and clamped in place, there is an expectation that the slots in the centering rings will match up with the slots in the body tube and the angle and twist will be true. Sure don't want the wings to be fighting the fins for directional control.
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The U-brackets have no nuts on the top side as there was no room. The hope is that the liberal use of epoxy covering threads on both sides will be enough to keep the brackets from ever coming loose.
 
Cool build! Wings do make things float, does the drogue break in the middle or blow the nose?

Long Tom definitely caught the wind a bit during drogue descent in both of its flights so far, but it wasn't too bad under the 24" Estes Pro Series II chute.

You can tell by how often it lifts up to look at the horizon (which made for some great screen grabs!)



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The first "wing" glued in place.

Some bug inside my head drove me to get back to this project. This step has been a little like a Rubik's Cube exercise as all the disparate pieces have to line up in a certain way, in a certain order, to produce the symmetry and functionality required for a stable platform. There is always the concern that an intricate piece will be glued in place only to find out after the fact that some other part will not fit. Okay, it's part of the challenge of modifying a perfectly good kit that only requires one to follow the instructions. Those poor LOC Precision guys (who have become quite lately on custom work...) have to be concerned that Mad Mr G is creating a monster out of a basic Big Nuke.
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At last, the cockpit is glued to the nose cone. A pound of BB's was added to the tip of the nose cone for CG balance and a bulkhead with a U-bracket was epoxied half way up so there is plenty of space for electronics and deployment apparatus.
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The fins have now had the belt sander treatment with a 400 grit hand sander finish to give that nice airfoil look.
 
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The wing assembly ate up a good portion of the drogue chute bay so I decided to use the Eggtimer Quark for dual deploy given its size. Knowing that for my future L3 certification, there is a requirement for a backup altimeter, I decided to make a modular system that would provide dual altimeter function in any eBay from 54mm up. This will allow some experience with the unit and easy installation into the 4" fiberglass Tomach when the time comes.
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When all trimmed up, the total length comes out to about 4.5 inches. The 8-32 threaded rods are the standard 1.5 inches apart matching many existing altimeter bay plate holes. Holes 180 degrees apart will be drilled in the body tube for a screwdriver to fit in and turn off and on the altimeters. A little unconventional, but hey, so are the other mods on this kit.
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Each Quark has a rechargeable 3.7v battery so charging can be done without disassembling the unit.

With this finally accomplished, the eBay assembly can be completed. All internal and external fillets are done so, with a bit more work on the cockpit fairing, the first coat of primer will be applied.
 
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Epoxied the lower Ebay plate in the coupler with a stiffy tune to help protect from zippers. It's a bit of a tight squeeze getting the wire connectors together inside the Bay before closing everything up.
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Found the culprit for the main ejection charge firing on the pad. The red wire had separated from the circuit board where the on/off switch attached leaving an open circuit. When I turned the screwdriver to the switch's On position - boom! Pretty scary at the time, especially with a 5 lb nose cone on the loose. Bonking me in the head on the way down hopefully knocked some sense into me. At least I can say the ejection charge has been ground tested...
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I like the dual sleds, that's clever.

Are those PVC caps being used for charge wells? Is there any downside to using PVC for that purpose?
 
First time PVC cap user. It's Schedule 40 with a wide mouth and not even half full of FFFg black powder. No concerns based on the first firing. Anyone else have issues with PVC for ejection canisters?
 
First time PVC cap user. It's Schedule 40 with a wide mouth and not even half full of FFFg black powder. No concerns based on the first firing. Anyone else have issues with PVC for ejection canisters?
I use them a lot. No issues at all. Here is my 5.5" loc bullet.
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I use them a lot. No issues at all. Here is my 5.5" loc bullet.
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I have the same kit, with the same ebay configuration - have you tried connecting an ematch to the screw terminal block on the recessed ebay bulkhead yet? I'm a little concerned making that connection is going to be harder than it looks.
 
I have the same kit, with the same ebay configuration - have you tried connecting an ematch to the screw terminal block on the recessed ebay bulkhead yet? I'm a little concerned making that connection is going to be harder than it looks.
I have. Not too bad. Strip enough wire so you can fold the wire back on itself before you insert it. Kind of makes a spring that holds it in place.
 
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