Stock as possible LOC Magnum: "Price of Admission"

Wait till you see the evening.

Ari.

iter said:

Wait till you see the evening.

Ari.

Click to expand...

I'm looking forward to it!

Some of my friends complain about PoA's A/V bay missing blast caps. I rectify this deficiency by recycling 4 D11-P casings.

I install 10-32 threaded inserts for rail buttons. The 1515 buttons come with 10-size holes, but 1010 buttons have 8-size holes and look too skinny to drill out to size. My solution is to tap a 10-32 thread in them. Now I can use either size buttons in the same inserts.

I install shear-pin shears in the booster tube.

I test the casings and the rest of my pyrotechnic installation. Apologies for the dim light--days are getting longer but they are still short. I'm happy with the results.

[video=youtube;I-xrc_92Bzg]https://www.youtube.com/watch?v=I-xrc_92Bzg[/video]

[video=youtube;A4UrgMez5_8]https://www.youtube.com/watch?v=A4UrgMez5_8[/video]

iter said:

Some of my friends complain about PoA's A/V bay missing blast caps. I rectify this deficiency by recycling 4 D11-P casings.

Click to expand...

Haha! I thought I was the only one that did that. Just as a matter of personal preference I sometimes give my bulkheads a coating of epoxy to protect them from the soot and whatever.

iter said:

I install 10-32 threaded inserts for rail buttons. The 1515 buttons come with 10-size holes, but 1010 buttons have 8-size holes and look too skinny to drill out to size. My solution is to tap a 10-32 thread in them. Now I can use either size buttons in the same inserts.

Click to expand...

This I am not so sure about. Those heads on those bolts might be problematic with some rails. I'd either test fit those in the rail you are flying on or get some lower profile heads. I know this isn't always possible and isn't always needed but Ideally if you can get the top of the head flush with the top of the button that is perfect.

iter said:

I install shear-pin shears in the booster tube.

I test the casings and the rest of my pyrotechnic installation. Apologies for the dim light--days are getting longer but they are still short. I'm happy with the results.

Click to expand...

You should be. That's looking downright perfect.

Nice build so far, but one fiddly point is bugging me....shouldn't the flange of the 10-32 insert be on the inside of the airframe? To spread the load and prevent it from pulling out...

G.D.

qquake2k said:

Your ground tests looked good. Where did you get 1515 rail buttons that take #10 screws? The ones I got from Dog House take 1/4" screws.

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Both my button sets are from LOC.

DAllen said:

Haha! I thought I was the only one that did that. Just as a matter of personal preference I sometimes give my bulkheads a coating of epoxy to protect them from the soot and whatever.

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Yes, plugged Ds are uncommon :=)

There's already a coat of polyurethane on the bulkheads. I'm debating coating the "bast caps" as well now that I'm using them.

gdiscenza said:

Nice build so far, but one fiddly point is bugging me....shouldn't the flange of the 10-32 insert be on the inside of the airframe? To spread the load and prevent it from pulling out...

Click to expand...

Thank you. Maybe we're thinking about different inserts. The ones I'm using are flange-less and look like these: https://fastenerline.com/tapped-brass-wood-inserts/54140-10-32-solid-brass-tapped-wood-inserts.html

The base color coat is on.

Ari.

iter said:

Thank you. Maybe we're thinking about different inserts. The ones I'm using are flange-less and look like these: https://fastenerline.com/tapped-brass-wood-inserts/54140-10-32-solid-brass-tapped-wood-inserts.html

Click to expand...

OK, I think I understand...the rail button inserts are the brass things in picture #2, and the shear pin cutter is picture #4... That shear pin cutter is what I use for forward rail button attachment on my rockets, and I install it with the flange to the inside.

G.D.

You're exactly right.

The t-nuts are 4-40 size though. I install them narrow face to narrow face, so they act as scissor blades. I have to file down the ones that go in the body tube otherwise they protrude. This has the side-effect of giving them a sharper edge for cutting.

Ari.

Base coat is on.

Ari.

Decals are on. I'm less impressed with my decorating than I expected.

Ari.

iter said:

Decals are on. I'm less impressed with my decorating than I expected.

Ari.

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Oh c'mon that looks great!

Looks real good! That's a big ass Magnum!

Did you intend to give it a Mercury Redstone look?

Looks great! I find paint schemes tend to grow on you more and more as time passes.

Cool! Nice quick build, and pretty darn stock.

What motors are you planning to fly this thing on?

rocketgeek101 said:

Did you intend to give it a Mercury Redstone look?

Looks great! I find paint schemes tend to grow on you more and more as time passes.

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Funny, but this is really true. First time I painted my L1 bird I felt the same way... Now it hangs on my wall, and I find it beautiful...

And never re-paint a rocket! It angers the rocket gods!

qquake2k said:

It looks great to me! I love a rocket that's taller than a door frame.

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Thank you Jim. And it still fits in the van in one piece :=)

rocketgeek101 said:

Did you intend to give it a Mercury Redstone look?

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Huh, I'm glad it's coming across. Yes, that's MR is what I'm trying to allude to. It ended up more cartoonish than I had in mind originally :=)

patelldp said:

Cool! Nice quick build, and pretty darn stock.

What motors are you planning to fly this thing on?

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I have a K695 waiting for tomorrow. I want to see how it does on that, and go from there.

Ari.

If you're coming up to launch with us tomorrow I will bring the tow strap just in case. LOL!

But it sounds like you're headed for TCC.

I'm afraid I am Kit. After the rain I willed on you last Saturday, I'm bailing out this weekend. I feel bad for doing that :=) Also, I'm going to miss the soft grass at SARG.

I have a friend who wants to share a ride to TCC but not to SARG though. It's a lot less boring drive when you have someone riding shotgun.

I'm looking forward to seeing you guys in three weeks at Snow Ranch!

Ari.

iter said:

I'm afraid I am Kit. After the rain I willed on you last Saturday, I'm bailing out this weekend. I feel bad for doing that :=) Also, I'm going to miss the soft grass at SARG.

I have a friend who wants to share a ride to TCC but not to SARG though. It's a lot less boring drive when you have someone riding shotgun.

I'm looking forward to seeing you guys in three weeks at Snow Ranch!

Ari.

Click to expand...

We're friendlier at SARG than TCC is. :tongue:

That is so true Jim. I was looking forward to seeing you guys tomorrow.

Ari.

Short version: I lowballed the price.

Longer version: flies good on K695, shreds on M650.

Longer version: the K flight is a pleasure to look at, even though the main deploys partially. A shroud line fouls the chute and it fails to inflate. Even with a partial main, the rocket lands safely and about 100' away from the pad. You can see the tilt angle in the pre-launch photos--I'm getting handy with wind speed, launch angle and flight side profile features in OpenRocket. The LCO jokes about how I must have planned the landing so close to pads, but that's exactly what happened.

The M flight is nominal until 2,000' or 3,000', when one of the fins apparently breaks off. The rocket then starts leaning over while still under thrust, the motor tries to get ahead of the rocket, rocket bends and the payload tube fails. It is likely that this happens as the rocket goes transonic (OR prediction max airspeed M .88) and the fins flutter.

Some interesting observations about what fails and what survives. All 3 fins break off at the surface. The 1/4" plywood fails completely, but the fincan holds. In fact every single glue line holds--and they are all yellow glue (only epoxy on this build is the JB Weld in motor retainer). The nose cone attachment holds, even as the main deploys at transonic airspeed. The failures that occur (besides the obvious zippers) are in the TN shock cords. Both cords fail, and both fail at the parachute attachment points. Specifically, both fail where swivels attach to the shock cord.

I'm waiting for photos to bubble up (I remember several people taking photos), and I still need to decode telemetry data.

I am sad that the price of admission is higher.

Ari.

Thats a bummer!! I liked the looks...

That's a bummer! I didn't know the magnum could take those loads... I may be purchasing one.

Well I guess, take is the wrong word... More like fit haha.

Looks like the bits are reusable though.

iter said:

Short version: I lowballed the price.

Longer version: flies good on K695, shreds on M650.

Longer version: the K flight is a pleasure to look at, even though the main deploys partially. A shroud line fouls the chute and it fails to inflate. Even with a partial main, the rocket lands safely and about 100' away from the pad. You can see the tilt angle in the pre-launch photos--I'm getting handy with wind speed, launch angle and flight side profile features in OpenRocket. The LCO jokes about how I must have planned the landing so close to pads, but that's exactly what happened.

The M flight is nominal until 2,000' or 3,000', when one of the fins apparently breaks off. The rocket then starts leaning over while still under thrust, the motor tries to get ahead of the rocket, rocket bends and the payload tube fails. It is likely that this happens as the rocket goes transonic (OR prediction max airspeed M .88) and the fins flutter.

Some interesting observations about what fails and what survives. All 3 fins break off at the surface. The 1/4" plywood fails completely, but the fincan holds. In fact every single glue line holds--and they are all yellow glue (only epoxy on this build is the JB Weld in motor retainer). The nose cone attachment holds, even as the main deploys at transonic airspeed. The failures that occur (besides the obvious zippers) are in the TN shock cords. Both cords fail, and both fail at the parachute attachment points. Specifically, both fail where swivels attach to the shock cord.

I'm waiting for photos to bubble up (I remember several people taking photos), and I still need to decode telemetry data.

I am sad that the price of admission is higher.

Ari.

Click to expand...

Wow Ari, looks like you got more excitement than you paid for! I'm very surprised that the 1/4" plywood fins broke like they did. I never would have thought that could happen. I'm also surprised that the tubular nylon failed. Did it actually break? Were the breaks at the knots? But I'm glad you got one successful flight before it shredded. Were you attempting your Level 3? Are there videos of the flights?

I love the photo of you and Leah!

iter said:

Some interesting observations about what fails and what survives. All 3 fins break off at the surface. The 1/4" plywood fails completely, but the fincan holds. In fact every single glue line holds--and they are all yellow glue (only epoxy on this build is the JB Weld in motor retainer).

Click to expand...

Ari,

Nice build, and I'm sorry to see what an M did to your rocket. However, I'm also going to make some lemonade with your lemons here. I have long maintained that for plywood/cardboard rockets, epoxy is overkill, and this failure proves what I believe. Your glue joints are noticeably stronger than the surrounding material.

Unfortunately, you would have benefited from a large amount of epoxy, in the form of tip-to-tip fiberglassing.

Now you have room in your rocket stable for a new HP rocket!

G.D.

Two photos from Peter Hackett: first, liftoff on K695, second on the away pad with the M just lighting up.

Ari.

Score one for yellow glue!!

iter said:

Short version: I lowballed the price.

Longer version: flies good on K695, shreds on M650.

Longer version: the K flight is a pleasure to look at, even though the main deploys partially. A shroud line fouls the chute and it fails to inflate. Even with a partial main, the rocket lands safely and about 100' away from the pad. You can see the tilt angle in the pre-launch photos--I'm getting handy with wind speed, launch angle and flight side profile features in OpenRocket. The LCO jokes about how I must have planned the landing so close to pads, but that's exactly what happened.

The M flight is nominal until 2,000' or 3,000', when one of the fins apparently breaks off. The rocket then starts leaning over while still under thrust, the motor tries to get ahead of the rocket, rocket bends and the payload tube fails. It is likely that this happens as the rocket goes transonic (OR prediction max airspeed M .88) and the fins flutter.

Some interesting observations about what fails and what survives. All 3 fins break off at the surface. The 1/4" plywood fails completely, but the fincan holds. In fact every single glue line holds--and they are all yellow glue (only epoxy on this build is the JB Weld in motor retainer). The nose cone attachment holds, even as the main deploys at transonic airspeed. The failures that occur (besides the obvious zippers) are in the TN shock cords. Both cords fail, and both fail at the parachute attachment points. Specifically, both fail where swivels attach to the shock cord.

I'm waiting for photos to bubble up (I remember several people taking photos), and I still need to decode telemetry data.

I am sad that the price of admission is higher.

Ari.

Click to expand...

Something I have been preaching for a long time and will probably use this thread as an example. The glue is stronger than the material it is bonded to when applied correctly.

But running some quick and dirty OR sims shows that an M650 puts that bird squarely in the transonic (+/- 10% of Mach - roughly) region at about 750mph. Not a good velocity for rockets to be hanging out for long periods of time as I understand it. I don't know the exact technical reasons but I've been told it has to do something with the large increase in aerodynamic pressure right around mach (maybe someone else can explain it.) Here's a fantastic example of this phenomenon:

[YOUTUBE]M_FCQ550770[/YOUTUBE]

That is Art Upton and I believe that was at the 2005 LDRS in Texas.

Even with a large amount of tip to tip FG it may not survive hanging out in the transonic region for very long. You want a motor to either stay at least 10% below mach or punch through mach quickly. You rocket might have survived a much faster buring M like a M1315 built as is which would have had a top speed around 950-1000 mph. Even then the ply may flutter into oblivion anyways.

As I have hinted at already - keep in mind I have zero personal experience in this area so I'm just repeating what others (more knowledgeable than I) have taught me.

-Dave