L3 Practice Phoenix

[Eric]

I am going to do a large level 2 build, as practice for level 3 techniques. I would like any input or advice. It’s going to be a ½ scale AIM-54 Phoenix. The build will be out of LOC 7.51 tube with full couplers for added strength. I have done my best trying to get scaled dimensions to ½. Except the weight that will be 1/25^th scale at about 40lbs with a big motor. It will be 78” in height and have an 18” wing span. No sure if I like the white or gray paint scheme better.


The forward fins are going to be quite the project. They will be 28.25” long, 2” leading edge, 5.25 trailing edge. There will be 18” of TTW engagement into the fin can. The aft fins will have a semi span of 5.25” and root cord of 7”.
I picked up most of the unassembled parts from an abandoned project. The fin can was the only item that was mostly assembled. It originally looked to be a ½ Patriot. It has three 5/8” 7 ply centering rings around a 75mm PML phenolic motor mount. An Aeropack 75mm flanged retainer is screwed on the back. Two 5/16-18 all threads tie the fin can together. The recovery harness will attach to 2 U-bolts through the forward centering ring.


To start with the fin can. The aft fins were trimmed from there odd ½ “Patriot” fins to their proper scale, then beveled. I added the second U-bolt to the forward centering ring. I had to sand down the forward centering ring to fit inside a coupler. The 28” motor mount inside the 30” body tube didn’t leave much room for a coupler. So the 30” lower body was extended 12” prior to installing the fin can.


The forward fins are made from ¼ plywood with a layer of 7oz glass and west system. I made up a template and drew out the fins around a couple flaws in the sheet. After about 3 coats of primer and sanding it turned out very smooth, and much stiffer with the fiberglass. I need to buy a good band-saw. Cutting with current methods (table saw or skill saw) is going to require a lot of sanding.

 

[CoyoteNumber2]

If you're putting in the effort to make an M-capable rocket, why not make it your Level 3 project?

 

[markkoelsch]

Yep. Make it your L3 and be done.

 

[Eric]

The fins, MMT and CR's were assembled by someone else.
I don't meet rule 2.1 (a-c)
And No plans were submitted to an L3CC.

 

[Steve Shannon]

The fins, MMT and CR's were assembled by someone else.
I don't meet rule 2.1 (a-c)
And No plans were submitted to an L3CC.

That shows good judgment and restraint. I'm sure that when you do build your L3 rocket you're going to do great.
In the meantime this project looks great!

Steve Shannon

 

[markkoelsch]

The fins, MMT and CR's were assembled by someone else.
I don't meet rule 2.1 (a-c)
And No plans were submitted to an L3CC.

I see. That makes sense then.

 

[Nytrunner]

This should be fun!
I'm probably going to get a Phoenix for my next 38mm rocket.

Is this going to be primarily an L flyer?

 

[Bat-mite]

Heck, yeah. L3 will be a cake walk after this.

 

[Eric]

This should be fun!
I'm probably going to get a Phoenix for my next 38mm rocket.

Is this going to be primarily an L flyer?

Yes, mostly L motors. Rough guess sims look like 2500'-4500' on L motors. But I also like the lower ~2000' flights some bigger K motors will give it.

It will be a high beauty over a high performer. I love all that fin. Unfortunately they don't give me great stability numbers. Not accounting for base drag, I'm only looking at 1.5 caliber.

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[Nytrunner]

Yes, mostly L motors. Rough guess sims look like 2500'-4500' on L motors. But I also like the lower ~2000' flights some bigger K motors will give it.

It will be a high beauty over a high performer. I love all that fin. Unfortunately they don't give me great stability numbers. Not accounting for base drag, I'm only looking at 1.5 caliber.

Sent from my VS988 using Tapatalk

No one will fault you for adding weight in the nose for a scale model if it'll make things safer!
That's what I had to do for the L1 Patriot, It's what I'll probably have to do for my L2 Tomahawk, and If I ever do L3 on an IRIS-T, I predict nose weight will make an appearance.

 

[markkoelsch]

Whatever you do, please do not fly it in much wind...it will seriously weathercock.

 

[Tim51]

Very interesting project, and as you have pointed out, a challenging project to learn from on the road to L3. Thanks for sharing the journey I look forward to foliowing your progress from afar. Good luck!

PS - in terms of colours, just a random suggestion: if you're not too keen on the overall white or grey, suggest use the same colours but reverse the order (e.g. - from the first pic, mainly dark blue with white bands / text , or from the second overall yellow with grey detailing etc. My rationale is it might keep the feel of the originals, but with a creative twist).

 

[Nytrunner]

Very interesting project, and as you have pointed out, a challenging project to learn from on the road to L3. Thanks for sharing the journey I look forward to foliowing your progress from afar. Good luck!

PS - in terms of colours, just a random suggestion: if you're not too keen on the overall white or grey, why use the same colours but reverse the order (e.g. - from the first pic, mainly dark blue with white bands / text , or from the second overall yellow with grey detailing etc. My rationale is it might keep the feel of the originals, but with a creative twist).

^^Upvoting that. Navy with white stripes could make it look like a really Big dummy-round. Make it entirely your own!

 

[Eric]

That is great color advice. I like the idea of keeping it the same theme, just flipping colors.

I haven't been able to find more then a couple larger "Phoenix" projects.

But I was always under the impression that weather cocking was worse with really over stable models.

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[ECayemberg]

That is great color advice. I like the idea of keeping it the same theme, just flipping colors.

I haven't been able to find more then a couple larger "Phoenix" projects.

But I was always under the impression that weather cocking was worse with really over stable models.

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Cool project! Looking forward to following along!

Loc just came out with the 7.5" Phoenix; which flew great at Airfest this past weekend. 3500 Newton Second L850 took it to a bit over 3000'. Had ~5lbs of noseweight, flew dead straight, though the winds were calm.

Big Phoenix's are sooo cool!

 

[Bat-mite]

Cool project! Looking forward to following along!

Loc just came out with the 7.5" Phoenix; which flew great at Airfest this past weekend. 3500 Newton Second L850 took it to a bit over 3000'. Had ~5lbs of noseweight, flew dead straight, though the winds were calm.

Big Phoenix's are sooo cool!

Got a link to the LOC 7.5" Phoenix? I can't find it anywhere.

 

[djs]

Got a link to the LOC 7.5" Phoenix? I can't find it anywhere.

It's coming out soon, I think, along with some other larger kits. pictures/video on the LOC Precision fb page.

 

[ECayemberg]

Got a link to the LOC 7.5" Phoenix? I can't find it anywhere.

I believe AMW is the only one with them in stick at the moment. Brand new so haven't really escaped into the wild too far yet.

 

[Eric]

Dang.... I could have got a kit..... Lol. I'm good with scratch built.

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[isobig]

Can't wait to see it finished. Here is my Phoenix which is approx. 42% scale. Only flown once way back in Sept 2004 on a AT J570. Sat in storage since then. I repainted it in 2016 and put decals on. It has a 54mm motor mount and decals are from Stickershock. Hope to fly it again next year.

 

[Eric]

That's beautiful.

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[Bat-mite]

Nice!

 

[Eric]

I was able to do some fin cutting at work. Took a lot of work to get these fins made. After doing 4 layers of sanding and priming. I rough cut them all out on the band saw. Then I stacked them all together and cut them down to there final dimensions. I just need to sand the cord length strait.

I still undecided what taper I want to put on the fin edges. There won't be any pretty fillet on the forward fins. I am going to have scaled flanges running the root cord.

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[Tim51]

Glad you're going for the flange option. Hope it works ok. Coincidentally I was thinking about that same issue looking at another flier's Phoenix at my club launch recently. I haven't seen flanges done before, but it certainly makes a noticeable difference to the look of the real thing.

 

[Andrew_ASC]

Unfortunately they don't give me great stability numbers. Not accounting for base drag, I'm only looking at 1.5 caliber.

That's decent for a scale missile. I think the sweep angle does this. You can add as much mass to the nosecone forward section to shift CG as you need. On a L-1 Wildman RB-05A Sport Kit it legit needed a pound of lead in nose with epoxy, because stock was -0.333. The bigger RB-05A's with 75mm motor mounts needed several pounds of lead from what I've read. So the Phoenix isn't a bad choice at all.

 

[Andrew_ASC]

Whatever you do, please do not fly it in much wind...it will seriously weathercock.

I had 1.7 Stability cal in a Wildman RB-05A Sport with pound of lead in nose. 3.5 lb loaded. It had to have been blowing 10-15 mph on ground with 30mph winds aloft at 5000ft. I300T on L-1. No weather cocking. I think it depends on rail exit velocity, motor selection, winds, and stability if the thing is going to weather cock. Just punt it up real fast on a beefy motor.

 

[Eric]

I also believe the flanges are a must for this larger scale version.


I have the understanding that a 1 caliber stable rocket like this one, would weather cock way less the highly over stable rockets.

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[dr wogz]

I prefer the white scheme, but I've found white rockets get dirty.. fast!
Sooty hand prints, muddy fin tips, the odd rail streak (black, again), grass stains..

 

[Eric]

Well, after letting this thing sit sadly in a corner. I decided to continue on and mount the forward fins.

I used a little epoxy on the fin tab, then tapped them into place. The fin slots were a little tight and needed the use of a rubber mallet to get everything seated. After they were lined up with their aft fin. I drilled small holes every inch along the root. Give the epoxy more to grab on the cardboard and plywood fin



The epoxy area received scuffing with 80 grit sandpaper any good wiping of acetone. Then I'm asked everything off to keep epoxy where I wanted it. Since I had a good amount yet left I'm using System Three T-88



Since this area will be covered with its fin root flange, very little effort was used to keep epoxy pretty. I will be drilling a few holes through the forward centering ring in order to inject some internal fillets.

 

[Andrew_ASC]

Yes he’s back at it again! This will be quite a crowd pleaser low and slow when you finish it! HARA had a L2 half scale patriot and another large L2 AMRAAM that were gorgeous to watch on K motors last year. Those were more exciting than the L3 flight because everything was within visual in my opinion. I also saw a L3 project fail this spring and break up in flight due to builder errors. So this extra practice is good. Phoenix shall rise from its humble corner and soar!