Mega Mosquito Malefunction

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Kirk G

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After repairing a cracked fin that came loose at the first of the year (due to a lack of fillets attaching the fin to the engine mount...construction error) I launched my favorite rocket with a square of nomex wrapping up the plastic chute and some dog barf as well. (a handful or so)

The nose cone deployed, and the nomex square (which was not attached to the rubber shock cord) sailed away when the chute deployed. We had a nice recovery. The nomex square was found, dirty and soiled but intact and usable.
While carrying the rocket back to pad, I spotted a ding in the front leading edge of one of the fins (not the one repaired recently). While it spoiled the airflow, it was not a crack and I assume that it was the nosecone impacting the fin.

A second repack also didn't attach the same nomex square (which was recovered) and again, a launch on a second D12-3 was successful, except the rubber shock cord wrapped around a fin in a half hitch, and the chute did NOT deploy...the nomex and chute just barely still in the body tube, but no forward pull to remove and inflate it.

The Mega Mosquito came straight down, nose first, but trailing the nosecone behind it. A hollow thud as it hit indicated a direct impact.

Inspection revealed the tube nose dived into the ground and began to crumple, the nomex and chute almost but not quite pulled out when the shock cord wrapped around the fin. How to keep this from happening again?



It appears that I will either flying this one into the ground next month, or else rethink that nomex square to be wraped tighter and the nose cone not wedged in as tightly (it was HUMID @ 90 F) for launch day!

Any suggestions on what to look for? Why is the nosecone suddenly impacting the rocket fin, and is there a better way to utilize the nomex square in packing? Any tips on when the nosecone no longer slides in and out easily?

(YES, I have another Mega Mosquito kit new in the package, so I could and will eventually build another one, but first wanted to learn my lessons with this "damaged" one before risking another. I have a 3 pack of D12-5 for launch.)
Comments?
 
Cardboard tubes tend to absorb moisture and swell in humid conditions. This can be mitigated (but not completely eliminated) by sealing the end of the tube with CA.

As for the nose impacting a fin, use a longer shock cord. The one in my MM is about 5' long.

Good luck, and post pictures, already! :D
 
I would sand the part of the nose cone that goes into the body tube down as much as possible. I'm sure others will disagree with me on this but I like my nose cones to have a very loose fit. If it takes any force at all for the nose cone to be placed into the body tube it's too tight.


John Boren
 
Nope, you are not alone. Mine are loose as well, meaning if you point the rocket down the nose cone will fall out.
 
Punch a hold near a corner of the nomex, and feed your shock cord through it to hold the nomex with the rocket. Lengthen your shock cord. D12s have a fairly beefy ejection charge, so I wouldn't be so concerned with the fit of the nose cone. I would bet the ejection was either early or late on that last flight, and as soon as the NC separated, it went straight to the fin...once it wrapped around the fin, there was nothing pulling the SC/Chute out of the body tube anymore. For this reason, I tend to put my parachutes very close to the nose cone. ANd make sure they are wrapped fairly small so they come out easily.
 
Punch a hold near a corner of the nomex, and feed your shock cord through it to hold the nomex with the rocket. Lengthen your shock cord. D12s have a fairly beefy ejection charge, so I wouldn't be so concerned with the fit of the nose cone. I would bet the ejection was either early or late on that last flight, and as soon as the NC separated, it went straight to the fin...once it wrapped around the fin, there was nothing pulling the SC/Chute out of the body tube anymore. For this reason, I tend to put my parachutes very close to the nose cone. ANd make sure they are wrapped fairly small so they come out easily.

+1 on the nomex...also may want to add some CA to the hole edges to help prevent fraying and maybe use a swivel link and short kevlar cord so you can easily move/remove.

The MM instructions actually say to anchor the chute to the nose cone; however examining mine, even when anchored to the nose cone, the rocket body is short enough and the chute lines long enough that the nose can go under a fin with the chute still in the rocket! I would suggest making sure the chute is on the nose, possibly shortening the chute lines (not sure if I want to do that one though) and making sure that when you pack the chute, you roll it up in the chute lines as well as the shock cord so that it is a bundle which comes out as the nose cone is pulled out. Try a test a few times to check. Also one more trick is to add extra dog barf...looks ridiculous at apogee (and you may get comments about aerial littering), but it really can push everything out! lol

Best luck to you!
 
I've been having trouble with nomex lately – a lot of singed chutes, a non-deployment or two – so I decided to do something crazy and read the instructions that comes with the nomex.

The instructions say to slide the nomex square down the shock cord as close as you can get it to the end of the MMT. So basically, instead of thinking of it as a parachute protector that you wrap around the parachute, think of it as a baffle.

I've only launched one rocket since this discovery and the chute was already singed so I can't yet report on the effectiveness of this, but I'm hoping this is my problem, because the rate of failure I've had with the nomex makes me not want to use it, but they are so ubiquitous I figured it had to be me, not the nomex.
 
Longer rockets are easier, but for all rockets I install the wadding first, blow it down to the bottom (never 'ram-rod'), then install the shock cord and then install the properly folded parachute on top. First thing to come out of the tube MUST be the chute in case of weak ejection charge.

properly folded chute = fits easily into the tube, will come out without jamming or getting stuck on something inside (like a bad shock cord mount....) and when you let go of it, it unrolls itself and starts to open all by itself. Practice folding and wrapping the shroud lines until you get it perfect.
 
Longer rockets are easier, but for all rockets I install the wadding first, blow it down to the bottom (never 'ram-rod'), then install the shock cord and then install the properly folded parachute on top. First thing to come out of the tube MUST be the chute in case of weak ejection charge.

properly folded chute = fits easily into the tube, will come out without jamming or getting stuck on something inside (like a bad shock cord mount....) and when you let go of it, it unrolls itself and starts to open all by itself. Practice folding and wrapping the shroud lines until you get it perfect.

Ditto! Exactly.
 
One plastic parachute tip I like to pass on is to fold the chute sideways when transporting/storing the rocket (think opposite the way the instructions say to fold it)...fold the chute top down first then roll from one side to the other. When you are ready to launch, you then take out the chute and fold the correct way and this prevents the chute from holding it's folded shape. At the last launch I saw someone with a failed chute and she was holding it after recovery and it was tri-folded just like it came out of the bag. I also suggested using baby powder (talc).

Sorry if this is TMI. :)
 
One plastic parachute tip I like to pass on is to fold the chute sideways when transporting/storing the rocket (think opposite the way the instructions say to fold it)...fold the chute top down first then roll from one side to the other. When you are ready to launch, you then take out the chute and fold the correct way and this prevents the chute from holding it's folded shape. At the last launch I saw someone with a failed chute and she was holding it after recovery and it was tri-folded just like it came out of the bag. I also suggested using baby powder (talc).

Sorry if this is TMI. :)
That's about how I fold mine. I have swapped the same parachute for all of my D-E rockets without any failures. I make sure to remove the memory fold lines by working it with talc powder to fluff it up a bit. I always use the required amount of wadding and a little extra. I make sure that the wadding is loose enough in the tube that you could blow it out easily with your mouth. Never cram the chute in the tube for any reason because you have too much wadding, cord or the tube is too short. Refold the chute to make it shorter or reload the rocket. I will take the time to reload a rocket over again if needed and found that the shock cord was bond up in the middle of the BT.
 
The nomex square was found, dirty and soiled but intact and usable.

Even when using a parachute protector, you might still wish to use a sheet or two of recovery wadding (or a little "dog barf") inserted into the rocket before the protector. This will reduce how dirty the protector gets and help it last longer.

And, attach the protector to the shock cord! :)

- - Roger
 
Even when using a parachute protector, you might still wish to use a sheet or two of recovery wadding (or a little "dog barf") inserted into the rocket before the protector. This will reduce how dirty the protector gets and help it last longer.

And, attach the protector to the shock cord! :)

- - Roger

+1. In fact, if there is even a small spot where ejection gasses can pass by the chute protector, it can fuse/melt the chute. This happened to my Big Daddy and also burned a small hole in my Nike Smoke chute which I used a large Nomex on. I now make sure to always add dog barf just in case.
 
I have a lot of holey chutes...nylon kite tape works wonders :)
 
As for the nose cone fit, I like (the "standard" advice as I understand it) a fit such that when the rocket is turned upside down the nose cone stays in place, but will come out with a good little shake, i.e. not just a tiny jiggle but you shouldn't have to shake it hard either. A bit of powdered graphite can help, especially if stiction or temporary swelling is a problem.
 
A good HP tip if payload or nose cone has the right fit. When rocket is already for flight lift rocket by nose cone or payload section. If you see a little movement its perfect. It has always worked for me.
 
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