Performance Rocketry Mongoose 75

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Before I tackle the fin attachment, I'm going to mount a forward bulkhead in the upper part of the booster. This will serve two jobs--forward motor retention and drogue recovery harness attachment point. The 1/4" bulkhead is sandwiched between two one inch coupler sections. Here I've used the epoxy provided to make the bulkhead assembly.

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The center hole of the bulkplate was 1/4", so I drilled it to 3/8", the same as the tapped forward closure is on the AMW motors. I will use a section of threaded rod, a coupling nut, and a AMW forged eye bolt to secure the motor. I will make up 2 separate assemblies based on the motor used. They will be locked together with red Loctite so they don't unscrew in flight. I used blue tape on the booster section to show how long the AMW 75/6000 and 75/7600 cases are for reference. And the last picture shows how this will look once it is mounted in the rocket. (The short section of threaded rod will be used for the 75/7600 case). Time for some epoxy!

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What do you think of the Pro-Line epoxy that came with the kit?

Andrew Grippo
 
Andrew, have you used this in any of your waiver-tickling rockets? I used to use tubing but was in 4" rockets, and it worked well. I don't doubt it would work with the 'goose though, as long as there's enough -bang- to do the job way up there.
I haven't used it before but will be in a couple of weeks at LDRS. I have a fight planned for 26,500' and just got an email back from the BOD stating they approved the flight so I'm good to go.

Andrew
 
What do you think of the Pro-Line epoxy that came with the kit?
Andrew Grippo

My first reaction to the Pro-Line epoxy is very positive. The viscocity is closer to JB Weld than laminating epoxy. You can't just 'pour it on' and have it self-level --it won't do that, you have to 'apply' the epoxy where you want it, and to me that's a plus. Also, no added fillers will be needed when it comes time to tack on the fins or make fillets, so I won't have to worry about this stuff trying to run away from where it needs to be and dripping. Yep, good stuff--I like it.
 
I gouged the outside of the bulkhead assembly with my Dremel using a coarse grit drum sander. The inside of the body tube is very slick, so I roughed it up where the bulkhead is to be attached using a flap wheel sander mounted on a 12" extension. Now were ready for a little epoxy.

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I mixed a small amount of the epoxy and swabbed it on the inside of the booster using a small wooden stick, then installed the bulkhead assembly and left it to cure overnight.

After curing I measured the distance from the bulkhead to the top of the booster. I then subtracted the length of the ebay that will be inside the booster and I am left with ~8" of useable space. Should be plenty of room for packing shock cord.

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I got around to making a Rocksim file for the Mongoose, and one thing I was unsure of is where to mount the fins. I was thinking one caliber (3") up from the bottom. Anyway, I gave Curtis a call and he said yes, 3" is right on, so I drew up the following Rocksim file based on 3". It's just the components as delivered to me. You'll have to add for your electronics & recovery system.

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hey Kaycee, thanks for doing this thread. I've been stewing about how to build my Mongoose. your posts are very informative. I think I am ready to do it up, stock. It should be a quick build!

did you use Proline for fillets? seems like a good way to go ...

and - how are you going to put a tracker xmitter on it? my Beeline seems to xmit through the carbon just fine so I think I'll do the usual tape-on-the-shock-cord and just go for it.

hope you get yours back!! rock and roll!
 
hey Kaycee, thanks for doing this thread. I've been stewing about how to build my Mongoose. your posts are very informative. I think I am ready to do it up, stock. It should be a quick build!

did you use Proline for fillets? seems like a good way to go ...

You're welcome & Thanks! I haven't done the fin work yet--it's coming up soon, but yes I'll be using the Pro-Line epoxy for attaching the fins and making the fillets.
 
and - how are you going to put a tracker xmitter on it? my Beeline seems to xmit through the carbon just fine so I think I'll do the usual tape-on-the-shock-cord and just go for it.

I'll be using a tracker in the Graphite nose cone, using a removeable bulkhead. Here I've cut three 3/8" Birch mounting blocks from square stock and epoxied them into the nose cone.

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One small problem; CF will block most most of the signal of the tracker & or GPS.

I saw the quote & just maybe the Curtis's CF is more glass than CF???



JD
 
Here is what I posted on my Mongoose 54 nose cone highly scientific test.

Highly scientific yea right could not resist.
How about if I stuffed a BeeLine GPS into the Mongoose 54mm nosecone put the NC bulkplate on, placed all the above out on my deck and watched what would happen or not.
Turned on my Kenwood HT and much to my delight even with having to make some slight antennae bends to fit into the NC, the BeeLine GPS did in fact lock on the satellites to give altitude and coordinates.

Considering that I would like to make sure this not so inexpensive bird returns, the recovery electronics proper function is important.

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The nosecone reinforcement is glass and has no carbon fiber in it.
The surfacecoat is graphite based giving the cool look and high temp capability. We have done this so you can put tracking in the cone.

Thanks
Curtis Turner
 
You can allways have the antenna outside of the nosecone.
 
Antenna works fine inside the cone.
As Curtis Turner of Performance Rocketry indicated the nose cone was made to put tracking equipment inside it.
 
Kevin...? How is this beauty coming along? Are you going to fly it at a PMW launch any time soon?

Pics man! Where are the progress pics?

Johnnie
 
Kevin...? How is this beauty coming along? Are you going to fly it at a PMW launch any time soon?
Pics man! Where are the progress pics?
Johnnie

No pics=No progress.:( I'll update as soon as I can get back to the build.

(Recently I've been consumed by another project--something VERY special.):D
 
Then I used the supplied fin jig and tacked the fins on using the Pro-line epoxy. After curing overnight, I removed the jig and using the tape method, laid down some small fillets with about a 3/8" radius. Here is the result. Next on the list is to laminate the fins & body tube with a layer of carbon fiber cloth (tip-to-tip).

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Nice. Let's hope the T2T goes well with the CF. It'll look killer with a good layup.:D
 
Nice. Let's hope the T2T goes well with the CF. It'll look killer with a good layup.:D

Thanks...we'll know soon enough!

I made a templet that covered two fins and body tube out of copy paper. I used the cut-out as a guide. Then laid some 5.7 oz plain weave carbon fiber cloth on the table, and used tape to outline the size & shape as needed. I cut these out with scissors and then cut out 3 sections of peel-ply fabric. Then I covered the table with a sheet of .002 Mylar.

Time to get busy....

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After I was satisfied that the carbon fiber was wetted-out properly, I peeled off the tape from around the edges, lifted the carbon fiber panel from the mylar, and placed it on the fin area. Starting in the center with the body tube, I worked the cloth around the body tube/fin joint, then out to the tip of the fin. Then I added the layer of peel-ply and worked it into the resin to wet it out. I found that I needed to cut a few slots in the peel-ply to help it lay down at the fin-to-body tube transition so as not to get any air-gap between it and the carbon fiber. A few minutes later and I was done.

Tomorrow I'll strip off the peel-ply and reveal what is hidden underneath.

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Nice work. Can't wait to see what's under the peel ply.
 
Last night before bed I checked the 'goose to see how the lay-up of the first carbon fiber section was doing. I found that the peel-ply had pulled away in a few sections. :surprised:

At that point I went into 'panic mode'. Even though I had plenty of time before the epoxy cured, I decided I had to do something immediately if I wanted to get a nicer lay-up. After a few minutes of head scratching I came up with what would hopefully be a solution. I cut a few sections of mylar and placed them over the peel-ply, then put two G-10 fins that I had sitting around over that then clamped everything together. I said a little prayer and went to bed.

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Today was the 'unveiling' of the first of three T2T lay-ups and this is the result. The first picture is of the lay-up untrimmed, just after the peel-ply was removed. The second picture is after I cut most of the excess off using scissors and a box cutter.

I'm mostly pleased with the outcome but I will do a few things differently on the next set of fins. I will iron the peel-ply before applying in hopes that it will not try to lift off the fins and will use the clamping method described above. And in case you're wondering, I do own an iron...sort of. It's my wife's but tonight it's mine. ;)

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I've just finished the ebay. I'm not a fan of a single threaded rod down the center--it gets in the way of mounting electronics & batteries. I plugged up the center holes on the end plates with JB Weld and drilled two more so I could make use of two threaded rods for the sled to mount on. The threaded rods are 410 stainless steel as are the cap nuts & washers. The sled is G10 and the sled guides are Aerotech igniter tubes that were hardened with CA and epoxied to the sled. The switches are of the voltage selector type that I use in all my rockets. I made a riser for the switches out of flat aluminum stock, then drilled holes in the side of the ebay. I'll use a small screwdriver to arm both PF altimeters prior to flight. Additional vent holes will be drilled later. Here's a few pictures:

For all the money you spent on the rocket, why not go with a classier (or more costly) altimeter? Let me explain. I like PF don’t get me wrong they are really easy to use and work well, but the data and functionality that you recover from it is minimal. But on the other hand like RDAS, ARTS2, LCX, ADEPT ect, have many more functions and can recover lots of data from it. I am also aware space is limited but I have an ARTS2 and LCX and they probably could fit. Sorry if I offend anyone but I am all about mixing and matching altimeters (cheap one with expensive one)

My 1 cent (dwindling economy),

Gerald Jr.
 
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