Level 3 is my Ultimate Endeavor

I decided to go for my Level 3 cert using Pml's Ultimate Endeavor with a 75 mm motor mount. I haven't started gluing anything yet, have just been making parts.

Here's the obligatory unpacking photo:



I decided to start with the av-bay. Here's a photo of the bulkplates I cut using my relatively new router:

Looking forward to this one. There is nothing more awesome than a rocket with two fin sets.

Those tubes look nice, they don't have spirals ?

Area66 said:

Those tubes look nice, they don't have spirals ?

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I haven't notice that it looks like there are no spirals, but they are still there. They must be the micro-seam tubes where the spiral is nearly eliminated.

I had to go look at the tubes. Yes, there are spirals, but they are just deep and wide enough to catch a finger nail on. The tubes will get a double wrap of 6oz fiberglass, so that'll take care of filling the spirals.

I'm going to do naked carbon fiber tip to tip on the fins, and am trying to figure out what color scheme to do on the rest of the rocket to match. Gotta stay on budget with this, too.

gldknght said:

I had to go look at the tubes. Yes, there are spirals, but they are just deep and wide enough to catch a finger nail on. The tubes will get a double wrap of 6oz fiberglass, so that'll take care of filling the spirals.

I'm going to do naked carbon fiber tip to tip on the fins, and am trying to figure out what color scheme to do on the rest of the rocket to match. Gotta stay on budget with this, too.

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These are the fins for my Ultimate Endeavour with a 98MM motor mount.
Fin stock is 1/8" thick Fiberglass Nomex Honeycomb from ACP composites with 5 oz. Kevlar and 8 oz Carbon fiber laminated to both sides, vacuum bagged with peel ply, Breather Cloth and heat cured.

Then cut to shape and edged with 0.118" Carbon Fiber rod.

They are less than 1/2 the weight of the 0.125" stock fins and with no tip to tip they have survived flights on a CTI M1300 Imax Dual Thrust and M3100 White Thunder see picture.

Total rocket weight was around 32 pounds on the pad. Both flight were at or near Mach.


I highly suggest you foam your nose cone. A good friend of mine, troj, suggested this because PML nose cones are light enough to flex under the high aerodynamic loading of an L3 flight. I saw an L3 attempt at the last LDRS in Argonia, KS shred because the nose wasn't foamed. Terrible end to a beautiful rocket.

Sailorbill said:

I highly suggest you foam your nose cone. A good friend of mine, troj, suggested this because PML nose cones are light enough to flex under the high aerodynamic loading of an L3 flight. I saw an L3 attempt at the last LDRS in Argonia, KS shred because the nose wasn't foamed. Terrible end to a beautiful rocket.

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Well, I don't have the materials or the budget for making my own fins, so will stick with my plan.

An interesting idea about foaming the nose. I can't foam the entire cone, due to using some of the space inside for the gps tracker. But will have to look into foaming what I can.

gldknght said:

An interesting idea about foaming the nose. I can't foam the entire cone, due to using some of the space inside for the gps tracker. But will have to look into foaming what I can.

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There are a couple ways to handle this. 1) Put a tube in there to hold the electronics, and foam around it, or 2) Foam the whole thing, then use a spade bit to drill out the spot for the tracker.

I'd prefer 1 -- less mess.

-Kevin

troj said:

There are a couple ways to handle this. 1) Put a tube in there to hold the electronics, and foam around it, or 2) Foam the whole thing, then use a spade bit to drill out the spot for the tracker.

I'd prefer 1 -- less mess.

-Kevin

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Isn't that the truth. That is the one thing I hate about the foam. It is messy and if you get it on anything, it is next to impossible to get it all off.

troj said:

There are a couple ways to handle this. 1) Put a tube in there to hold the electronics, and foam around it, or 2) Foam the whole thing, then use a spade bit to drill out the spot for the tracker.

I'd prefer 1 -- less mess.

-Kevin

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Probably going to try the first method

gldknght said:

Well, I don't have the materials or the budget for making my own fins, so will stick with my plan.

An interesting idea about foaming the nose. I can't foam the entire cone, due to using some of the space inside for the gps tracker. But will have to look into foaming what I can.

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This is what mine looked like. I put a length of 5/6" threaded rod down the center with various sized washers and nuts on the end of the rod. Two nuts and washers held a 3" bulkplate at the point where the tube would contact the ID of the cone. I placed the tip of the nose cone in a container of water, mixed up some AeroPoxy, filled the tip to just below the bulk plate and let it cure. I held the rod centered using a 6" coupler bulkplate. After the epoxy cured I inserted the tubing with more AeroPoxy to attach it to the 3" plate. I held the tube centered with a centering ring. When that was cured I pulled the ring and filled the void left using small batches of Giant Leaps two part foam. When everything was filled I glued in the centering ring. The 6" bulk plate then covers the end. The tube gives me a place to mount a tracker and add nose weight if I need it.

That's very similar to what I have planned.

I promised myself I'd get something done on this project this weekend. I hate it when life gets in the way of my hobbies. So anyway, some photos of the fiberglassing of the inside of the coupler/av bay. I could not take pictures and apply the glass, so you all will have to take me word that it's in there.

More progress today. I epoxied together the bulk plates that I cut, these will augment the plates that came in the kit:



I think I'm going to fiberglass the surfaces of these plates that are exposed to the ejection charges, to make it easier to clean them and make them more durable. What do you guys think?

Wow not much interest in this build thread.
But, I found some time to work on this project today. About a week ago, I got the Av Bay bulk plates laminated with a layer of fiberglass. Today I installed the U-bolts and all thread. here are the photos:





I know, the top and bottom plates look almost identical, and they are. Next session, I will be installing the ejection charge holders and the terminal blocks. Then I get to work on the sled itself.

gldknght said:

Wow not much interest in this build thread.
But, I found some time to work on this project today. About a week ago, I got the Av Bay bulk plates laminated with a layer of fiberglass. Today I installed the U-bolts and all thread. here are the photos:

View attachment 127945

View attachment 127946

I know, the top and bottom plates look almost identical, and they are. Next session, I will be installing the ejection charge holders and the terminal blocks. Then I get to work on the sled itself.

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[Freddie Prinze voice ON]Loooking goood.[/Voice off]:clap:
I lined the inside of my coupler with two wraps Kevlar for added strength and did the balloon thing too.
My Endeavour puts all of the "laundry" out one end so my coupler design was somewhat different.
I had 1/2" bulkplates to start with, figured that was thick enough. Plus my main chute attaches to a central 3/8" forged eye nut and B7 threaded rod that can be attached to the motors forward closure.
I thought about coating my forward bulkplate with epoxy but never got around to it. Sort of wished I had. After three flights it has become a little grubby.

gldknght said:

I think I'm going to fiberglass the surfaces of these plates that are exposed to the ejection charges, to make it easier to clean them and make them more durable. What do you guys think?

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All you really need for that is a smooth surface; just mix some epoxy, then brush it on and let it self-level. The fiberglass isn't really necessary.

-Kevin

The fiberglass on the bulkplates probably wasn't required, but it's done. I used a encyclopedia sized book on top of a flat board on top of a sheet of wax paper to make sure everything stayed flat, and talk about a smooth surface. I figure since all the weight of the rocket will be hanging from these plates, a little overkill in this area won't hurt anything.

I was going to work on mounting the charge holders and terminal blocks today, but had a long day at Guard Drill, and not enough sleep last night, so I'm going to do a whole lot of nothing tonight.

Ok, after doing about ten minutes of research and not finding any straight answers, is there a consensus on the number of shear pins for holding a nose cone on? Is it the same number for holding the av bay to the fin can? On my Endeavor, both fit fairly loose. I'm thinking of using 2-56 screws for pins. i see folks using two and about the same number of folks using three.

gldknght said:

Ok, after doing about ten minutes of research and not finding any straight answers, is there a consensus on the number of shear pins for holding a nose cone on? Is it the same number for holding the av bay to the fin can? On my Endeavor, both fit fairly loose. I'm thinking of using 2-56 screws for pins. i see folks using two and about the same number of folks using three.

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Consensus? No, there isn't.

Personally, I'd probably use three on a rocket that size.

-Kevin

Personally, I'd use three 4/40 on a rocket that size.

Rocketeer Gator said:

Personally, I'd use three 4/40 on a rocket that size.

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I'm not sure why? The pins only need to hold against drag separation and the shock of the drogue charges going off. I'll probably test with 2-56 screws and see what happens. I can always go bigger if needed.

troj said:

Consensus? No, there isn't.

Personally, I'd probably use three on a rocket that size.

-Kevin

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I would use three as well. 2-56 size.

My main reason for saying I would use three is the configuration of the fins. Same reason my Nike Smoke has 4. Not the most scientific approach, but I like things to line up :tongue:



Braden

gldknght said:

I'm not sure why? The pins only need to hold against drag separation and the shock of the drogue charges going off. I'll probably test with 2-56 screws and see what happens. I can always go bigger if needed.

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Personally, I think the 2-56 will be more than adequate.

-Kevin

I don't use shear pins on my 4in DarkStar at all, and I bet the fiberglass components in that rocket are pretty close to the same weight as the phenolic components in this one will be after fiberglassing.

Also it's interesting to note that the diameter difference between a 4-40 screw and a 2-56 screw is only 26 THOUSANDTHS (.026) of an inch. Assuming they are both made of the same material, the shear strength will be entirely dependent on cross sectional area, 0.0058 in^2 for a 2-56 screw and 0.0099 in^2 for a 4-40 screw. So not that much difference. Also of note, the 2-56 screw has more threads per inch, so has a greater resistance to "pulling out". I don't really know if that matters.

UPscaler said:

I would use three as well. 2-56 size.

My main reason for saying I would use three is the configuration of the fins. Same reason my Nike Smoke has 4. Not the most scientific approach, but I like things to line up :tongue:


Braden

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I like your reasoning, it bother's my minor OCD when thing don't line up, or are not symmetrical.

gldknght said:

I don't use shear pins on my 4in DarkStar at all, and I bet the fiberglass components in that rocket are pretty close to the same weight as the phenolic components in this one will be after fiberglassing.

Also it's interesting to note that the diameter difference between a 4-40 screw and a 2-56 screw is only 26 THOUSANDTHS (.026) of an inch. Assuming they are both made of the same material, the shear strength will be entirely dependent on cross sectional area, 0.001849 in^2 for a 2-56 screw and 0.003136 in^2 for a 4-40 screw. So not that much difference. Also of note, the 2-56 screw has more threads per inch, so has a greater resistance to "pulling out". I don't really know if that matters.

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Uh, about 50% to 60% force differential: https://www.rocketmaterials.org/datastore/cord/Shear_Pins/index.php

gldknght said:

I don't use shear pins on my 4in DarkStar at all, and I bet the fiberglass components in that rocket are pretty close to the same weight as the phenolic components in this one will be after fiberglassing.

Also it's interesting to note that the diameter difference between a 4-40 screw and a 2-56 screw is only 26 THOUSANDTHS (.026) of an inch. Assuming they are both made of the same material, the shear strength will be entirely dependent on cross sectional area, 0.001849 in^2 for a 2-56 screw and 0.003136 in^2 for a 4-40 screw. So not that much difference. Also of note, the 2-56 screw has more threads per inch, so has a greater resistance to "pulling out". I don't really know if that matters.

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A single 2-56 takes 26 lbf to shear and a 4-40 takes 50, if I remember correctly, which I almost certainly am not. But my numbers are in the ballpark.

CarVac said:

A single 2-56 takes 26 lbf to shear and a 4-40 takes 50, if I remember correctly, which I almost certainly am not. But my numbers are in the ballpark.

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Close--21 to 25 on the first number and 38 to 40lbf on the second.

My predicted all-up ready-to-fly weight should be around 24 to 26 pounds. 3 2-56 pins at the nose and 3 at the top of the fin can will be more than sufficient, as Troj pointed out.