Failed L1 attempt

[Ben Martin]

I launched my 4" Patriot today on an H148R. The launch went perfectly up to after separation, where the force disconnected the nosecone from the body. I had thought this could be an issue before launch but I didn't do anything about it (besides taping the nosecone for a tighter fit), silly me.

What method do you recommend attaching it to the payload bay with? Plastic rivets, sheer pins, screws?

On a side note, everything else but the nosecone was recovered nominally.

All feedback is welcome.

 

[SteveThatcher]

assuming this was motor ejection, so the ejection charge blew the chute out and the nosecone? Plastic rivets or flat head or undercut flat head screws would work. I would not use sheer pins just because they are not as strong and may give way.

Also, sorry that the L1 flight didn't go as expected. We do learn from these things though...

 

[Ben Martin]

assuming this was motor ejection, so the ejection charge blew the chute out and the nosecone? Plastic rivets or flat head or undercut flat head screws would work. I would not use sheer pins just because they are not as strong and may give way.

Also, sorry that the L1 flight didn't go as expected. We do learn from these things though...

This is how the staging works, yes it is motor ejection. The nosecone is at the top of the payload bay, so the sudden jerk of separation caused the nosecone to fly off.

 

[Andrew_ASC]

Shear pins are designed to fail at certain force. Do not use shear pin. You could try more epoxy. I’ve had mentor show me how when more epoxy fails to hold a heavy 1lb nosecone to a body tube use a hole in airframe tube and a figure eight knot, it was a in the field fix. Possibly try more than one attachment shock cord point like a Y harness. Some use eye bolts. Some use epoxy. Some use knots. Recovery is always the hard part. Ask a experienced guy or gal at the launch site if you want, usually they are good at getting you certified ASAP. Sometimes some things are easier learned in person with someone showing you.

I’d personally try some epoxy on that nose. But others may have better advice.

 

[rharshberger]

Plastic Rivets or screws will do the job just fine to retain the NC, even wrap of aluminum HVAC tape around the outside of the nose to payload joint will probably do the job just fine. Shear pins can be used, but you have to verify that the ejection force is not enough to shear them. Another thing that will help is to secure the nose cone to the payload bay with its own short shock cord.

 

[crossfire]

This is how the staging works, yes it is motor ejection. The nosecone is at the top of the payload bay, so the sudden jerk of separation caused the nosecone to fly off.View attachment 363399

If your saying NC just came off the payload section? I just would use 2 o3 plastic rivets. They will work very well. You will get your L1 next time.

 

[Ben Martin]

Shear pins are designed to fail at certain force. Do not use shear pin. You could try more epoxy. I’ve had mentor show me how when more epoxy fails to hold a heavy 1lb nosecone to a body tube use a hole in airframe tube and a figure eight knot, it was a in the field fix. Possibly try more than one attachment shock cord point like a Y harness. Some use eye bolts. Some use epoxy. Some use knots. Recovery is always the hard part. Ask a experienced guy or gal at the launch site if you want, usually they are good at getting you certified ASAP. Sometimes some things are easier learned in person with someone showing you.

I’d personally try some epoxy on that nose. But others may have better advice.

The issue is that I did not have anything connecting the nosecone to the payload bay besides friction. I'm going to use plastic rivets to hold it on.

 

[Ben Martin]

If your saying NC just came off the payload section? I just would use 2 o3 plastic rivets. They will work very well. You will get your L1 next time.

Yeah that was my only issue. I have to buy a new nosecone, put weight back in it, and then install some plastic rivets. My nosecone is pretty heavy so that probably didn't help.

 

[Andrew_ASC]

Yeah. I would have glued the nose to the payload bay. Other people would likely run a eyebolt into the nose tip the shock cord to eyebolt on a bay.

 

[Andrew_ASC]

You ever fold shock cord in a Z in your hand? They call that ribbon folding. You might fit like 20 ft of Kevlar cord in that nose if you go the epoxied eyebolt into nose and shock cord route.

 

[SteveThatcher]

Yeah that was my only issue. I have to buy a new nosecone, put weight back in it, and then install some plastic rivets. My nosecone is pretty heavy so that probably didn't help.

I had a Patriot back in last millenia. You mentioning the added nose weight reminded me of how much weight I had to add to that rocket for stability back then. I used playa because it was handy at Blackrock in Nevada... Definitely use screws or rivets as suggested...

 

[Ben Martin]

You ever fold shock cord in a Z in your hand? They call that ribbon folding. You might fit like 20 ft of Kevlar cord in that nose if you go the epoxied eyebolt into nose and shock cord route.

I don't see a reason to have the nosecone come off as it doesn't have any purpose at the moment.

 

[Andrew_ASC]

Some people like to set up dual deploy. Wasn’t sure if you wanted to but described a technique.

 

[Ben Martin]

Some people like to set up dual deploy. Wasn’t sure if you wanted to but described a technique.

I'm likely going to stick to motor release and get a Chute Release soon for L2.

 

[wjmoser]

This is how the staging works, yes it is motor ejection. The nosecone is at the top of the payload bay, so the sudden jerk of separation caused the nosecone to fly off.View attachment 363399

I'd recommend not attaching the parachute directly to the payload bay. This is common in LPR but can cause issues with the often heavily weighted noses often found in HPR. I usually tie a larks head knot in the shock cord about 2/3 of the way up and attach the parachute through the loop created.

 

[Ben Martin]

I'd recommend not attaching the parachute directly to the payload bay. This is common in LPR but can cause issues with the often heavily weighted noses often found in HPR. I usually tie a larks head knot in the shock cord about 2/3 of the way up and attach the parachute through the loop created.

I've seen that done quite often, I'll probably try it out.

 

[grouch]

Just tape the nose. Make it easy on yourself. Besides, it looks cleaner.

 

[Ben Martin]

Just tape the nose. Make it easy on yourself. Besides, it looks cleaner.

Tape the outside or inside? Because I already tried taping the inside.

 

[grouch]

The inside.

 

[Ben Martin]

The inside.

Been there, done that. I heavy friction fit it and it still came out.

 

[grouch]

You may have been there but you didn't do it correctly or you'd have your L1. Pin it, glue it, use rivets, what ever. I'm just telling you how to do it easy and clean.

 

[Ben Martin]

You may have been there but you didn't do it correctly or you'd have your L1. Pin it, glue it, use rivets, what ever. I'm just telling you how to do it easy and clean.

How are you supposed to get it more than friction fit with tape? I put it as tight as possible and it still came out on ejection.

 

[grouch]

I used it all the time on my avbays. I even use it on my dual deploys. The trick is to wrap it in a slight spiral and add/remove tape to get the desired fit. You will need to twist the nosecone in. As far as tight enough, you can get it so tight you can't get the nose in. If yours popped off, it wasn't tight enough. It's also easy to check. Just toss the av section and yank on the shock cord. If the nose pops off, do something different.

Rivets and the like work but I think they are ugly and if you ever need to take the nose off for what ever reason it makes it real hard to line the holes back up without some sort of keying devise. You still want to make the nose removable, all sorts of fun things to put in there from read only altimeters and trackers and anything else you can think of. The red rocket in the avatar...tape.

 

[Ben Martin]

I used it all the time on my avbays. I even use it on my dual deploys. The trick is to wrap it in a slight spiral and add/remove tape to get the desired fit. You will need to twist the nosecone in.

Rivets and the like work but I think they are ugly and if you ever need to take the nose off for what ever reason it makes it real hard to line the holes back up without some sort of keying devise. You still want to make the nose removable, all sorts of fun things to put in there from read only altimeters and trackers and anything else you can think of. The red rocket in the avatar...tape.

It might have just been unlucky timing for the ejection charge, I'd have to look through the video to see. I'm going to stick with the strong friction fit with 2-4 plastic rivets so that I can take it off if I want to.

What are your recommendations for altimeter and trackers?

 

[Andrew_ASC]

TeleGPS and Telemini but not on an L-1 certification flight. No L-1 certification is worth losing expensive electronics over when it’s low enough for visual tracking.

 

[crossfire]

It might have just been unlucky timing for the ejection charge, I'd have to look through the video to see. I'm going to stick with the strong friction fit with 2-4 plastic rivets so that I can take it off if I want to.

What are your recommendations for altimeter and trackers?

I have used the plastic rivets for many years not hard at all to remove. On many of my 3-4" rockets I use tape friction fit and only 1 rivet and have never lost a NC. I have had very good luck using the Jolly logic chute release. I like to tie off my chute about 2-3' from payload section. Once chute deploys have chute tied at that point will keep NC from slapping into booster tube.

 

[muddymooose]

Whenever I want to impermanently secure two body sections, I put three small equally-spaced screws in them. I've done this to secure nose cones to payload sections or to secure a nosecone/payload section to an incomplete AV bay when using a chute release. I just make a dot on each section with a sharpie to make sure they're "keyed." Are the screws unattractive? Yeah a little I guess but I worry more about successful flights than looks.

I would never glue sections together. That would limit future flexibility.

 

[GalantVR41062]

If you want it removable you can do rivets, or a section of elastic shock cord and the tape/friction fit.

If the payload bay is hitting the shock cord that hard you might need a longer shock cord, or use less BP, is the air frame vented?

I have missile works alteters, RRC2+(2) and a RRC3. I have a couple JL3'S a Estes altimeter and a micropeak altimeter. The JL3 is nice, Bluetooth to your phone and instant data from the launch. I also picked up a missile works GPS tracker but have not used it. Our local club has trackers that you can barrow in rockets going over 3000'.

Before my L1 attempt another Estes PS2 Argent had the nose cone fall off, looked like it was only held on by some woodglue.

Live and learn, adapt, adjust fly more rockets. Good luck, I guess that's why we call them cert attempts.

~John

 

[Nytrunner]

How are you supposed to get it more than friction fit with tape? I put it as tight as possible and it still came out on ejection.

Don't take it personally, you've just been grouched.


That was my exact L1 rocket (H120) and I love it. At the time, I followed the instructions and epoxied the nose on. After a couple flights, the epoxy started cracking away from the polypropelene nose, so I ripped it off and use rivets now. Good call on the z-folding and chute release, I do the same.

They're great because now I can adjust the weight in the nose for heavier motors, and put trackers or altimeters in there too. At that point, I could have just shoved a J in there for L2, but then I really wouldn't have learned anything.

As far as alt's and trackers, I stick a simple Jolly Logic Alt 2 in non dual-deploy rockets. For trackers, I recommend checking out Eggtimer Rocketry if you're comfortable soldering, or the Missileworks T3 if soldering isn't your thing.

 

[DM1975]

Just get some cheap plastic rivets or some small self tapping screws. Problem solved, problem staying solved.