Need Mega Mosquito Advice Please

[Kirk G]

So today I took my Mega Mosquito out to fly again for the first time this spring. You will recall I built it last summer, and flew it a total of six times, on 3 D motors and 3 E motors. Five successful flights, though the Mylar chute started to melt.
Experiencing some singing of the Mylar parachute, I decided to swap it out for a yellow nylon reject from another rocketeer... and attached it with a fishing lure spring clip for my final flight of the year, last November. The shock of being opened before the rocket slowed sprung the clip, and the chute went floating away! The Mega Mosquito fell onto cut field grass, and survived without a break. Another veteran rocketeer offered to give me a brass swivel that was far more sturdy, and he looped it onto the shock cord about 1/3 of the way down from the nosecone. The yellow chute was rolled up and tucked inside the tube (WITHOUT RECOVERY WADDING) and sat all winter waiting.

Just before launching, I bought a new pack of D12-3 and prepared to launch, selecting a used red spacer to insert before the motor...which is held in place by a spring clip. Fortunately, a little voice told me to look for recovery wadding inside, and pulling the chute out, I found none in place. I took a hand of Dog Barf and dropped it inside as I normally do...but I also broke out two sheets of Estes Recovery wadding and wrapped it around the yellow nylon chute, to protected it from the gasses that had singed my last Mylar chute. Re-packing the chute, shock cord and nosecone inside, I assured that all was ready and prepared to launch.

I waited for the small breeze to slow, and then launched. The Mega Mosquito took off nicely, reached apogee or a little more, and then popped the nosecone off, BUT NO CHUTE DEPLOYMENT. The rocket and nosecone fell all the way to the short grass, but missed, and landed on a hard gravel road. Inspection reveals that one of the fins has cracked one side (fillet) but not the other. I examined the chute and wadding, and found the wadding was singed, but the chute was a little dirty but intact. I again carefully reloaded some Dog Barf, wrapped the chute a little tighter, and again wrapped 4 sheets of recovery wadding under the chute to protect it from hot gasses. Again, I reinserted everything in order...shock cord, chute, nosecone, and inserted the singed red spacer before walking and finding the final D12-3 motor and inserted it. The wire clip doesn't seem to be as tight, but it's still in there.

Again, I prepare to launch the final launch of the day, wait for the wind to die down, and again liftoff...sailing high, apogee, and then nosecone ejects, but nothing else. Again the rocket falls all the way to the cut grass surface, but this time, both sides of the fin fillet are cracked on that same fin. (Now, you'll have to note that when I assembled this bird originally, I didn't understand the necessity of gluing the root edge of the fin against the motor tube, and so though the fins are all filletted to the body tube, the inner most edge contacts the motor mount, but doesn't glue there...not at this time.)

As I walk to my car, I notice that the D engine has half ejected out the tail end of the rocket...no longer restrained by the metal clip. And as I get to looking inside the body tube, I find the Dog Barf and the yellow nylon chute both singed pretty darn good. I sit down in the drivers seat, and see laying in the green grass outside the door my singed red spacer...it may have fallen out of the rocket before I ever inserted the motor and I hadn't noticed. So I assume the last flight was without a spacer to take up space, force or blast. I had stepped on it as well, so it's now flattened anyway.

I am struggling to figure out what I have done wrong that my beloved Mega Mosquito will not eject a chute anymore. I have serious repair work on one fin if this bird will ever fly again. I have used up all my D motors at $5 each, and don't want to waste any more. Until or unless I am sure that it will eject and fly right.

What would you suggest I do to repair the fin?
Drill a hole in the rear centering ring and dribble wood glue down the root edge in a hope of gluing it in place?
Remove the fin and treat the end before re-inserting in the slot?
Use Super Glue? Carpenter Glue? Gorilla Glue?

How about the chute? Given that I'm using cord sewed into the 20" yellow nylon hexagonal chute, it's a little heavier, but now very soiled. I could remove it, wash it, but how to reattach? Should it be on the end of the nosecone? How about that brass swivel partway down the shock cord? I could move/remove that.

I have another red spacer for use if I need it for the next D motor, or should I try to reuse the original? And, I'm quite certain if the metal clip is still in place in the motor mount... I could bow it a little to hold better.
ANY advice would be welcome. I'd like to get several more flights out of this bird, rather than retire it. But what do you think?
I can post photos later to show any specific part.

Thanks.

PS: You may be wondering what came of the third D12-3 motor in that brand new pack. Just prior to these final two attempts with the MEGA Mosquito, I used the original motor in a Super Neon XL that had never flown, built just as the kit described down to the color scheme and fin placement..... And the bird flew perfectly. It went up, apogee, arced over and then ejected and opened the chute to a soft touch down on the cut grass surface. Very nice, satisfactory flight and performance. So I know the motors would appear to be correct and functioning well.

 

[Mushtang]

I don't think drilling a few small holes is thorough enough. You probably need to completely cut out the rear centering ring so you can do two things, inspect the motor mount and what condition the clip is in, and add glue fillets to all three fins at the root edge.

If you see a problem with the motor clip maybe you can repair it. If the clip is sliding you might be able to add a few drops of epoxy to the top end to anchor it in place. Or if there are other issues you can hopefully fix them.

When you're satisfied it's as good as you can get it a new centering ring shouldn't be that hard to find, or cut yourself. Scrape all the glue out of the inside where the rear centering ring goes and glue the replacement back in place.

That's what I would do.

 

[T-Rex]

I have learned that with any 24mm or 29mm motor, always wrap a small piece of tape around the motor and hook to strengthen the retention. I lost a 24/60 casing that way, which also resulted in a crash. (That is assuming that your hook is still in place, and not floating loose)
Your spacer should be able to be reused. Since it is only a spacer, just open it back up, place it inside a spare piece of BT50 and maybe smear a little wood glue around the ID to stiffen it.

As for the failed ejection it is hard to be sure, but I would say that the second time was due to the motor partially ejecting. A good test would be to load up your chute just like you did and blow into the bottom of the motor tube. That one should be small enough that you should be able to blow it all out. Maybe pack the chute different, allowing enough shock cord so the bundle ejects before it has to start unrolling.
You may have something in the tube that the chute is catching on (Estes 'teabag' shock cord mount?) How tight is the nose cone? Too loose or too tight, you wont get the chute out (should be identified by the blow test).

It may be faulty (small) ejection charge. Here again, difficult to prove.
I wouldn't retire it just yet.
Hope I have said something helpful.

 

[ThirstyBarbarian]

I'm not sure why it would not be deploying the chute, but there are a few things you could check.

If you take out all the recovery gear and wadding, hold one end of the rocket up to a light, and look all the way through the rocket, does it look like the motor tube has any kind of obstruction? I've had two Maxi Alpha Threes develop what looks like a pinched section in the motor tube, most likely from heat damaging the tube.

How tight is the nosecone? The advice I have received is that you do not want it too loose. You want it to move freely and not get jammed, but you also want a good seal. The nosecone should pop out with force, like a champagne cork, and pull the chute from the airframe. If it is too loose, put a bit of masking tape around the NC shoulder to make a tighter seal. Also, to help the momentum on the NC tug the laundry out, you probably want the cord that attaches the NC to the chute to be something non-elastic. It sounds like it is set up with elastic now and maybe the stretchy material dissipates some of the force needed to pull the chute out.

When you pack the new chute you are using, does it fit more tightly into the airframe than the old one? It needs to be able to slide out easily.

Regarding the spacer, I'd use a new one, not the squished one. You can also make a replacement by cutting an inch-long piece off the forward end of a spent D or E motor casing. Paint it orange if you like!

If the clip is loose at the frward end, is there a motor block in the motor mount? A cardboard ring glued in place to keep the motor from flying through if the clip fails? If so, and you can remove the clip, I'd replace it with a screw-on retainer.

If the clip is just loose at the aft end, then maybe you can bend it back. It also ok to tape the clip to the motor each time.

If the fin is loose enough to easily remove, I'd pull it out and reglue it properly. If it is still held in place, I'd try to make a hole and squirt some wood glue inside the fin can.

Good luck!

 

[Kirk G]

Good ideas all, guys. I like the idea of using an inch-long piece off a spent D motor. Yeah, I could paint it orange easily....just for visibility.
I double checked, and the spring clip is still there, still secure. I'm not sure why the motor was half ejected.

I'm thinking the nylon chute is more bulk, and the cord more substantial than the Mylar chute it replaced.
Haven't checked for obstructions or hang-ups...and yes, the rubber shock cord is secured inside with an Estes T-bag (cute name!)... I'll check to assure there's no hang-up there.

I had thought the nose cone was just a little more tight than I had remembered it being. If anything, I thought it should pop out more easily rather than resist... but I can see the idea there...especially if the shock cord is disipating the force of the ejection charge. I am concerned that the chute is not being pulled out with the nose cone. The cone is ejecting, but dangling...not enough resistance to pull the laundry out... but a firm tie down to the nose cone,(and perhaps wrapping the cords/guys around the nylon chute so that it has to unroll?) would probably assure that the chute gets blown out or dragged out.

In all earlier launches, I have been surprised that there is so much soot inside the rocket after it fires. (Perhaps this is true of all rockets and this is just the first one with a body tube large enough to fit a hand inside...and probably the one I have flown most often, for sure...) Is it regular practice to try to clean out a body tube, or remove some of that soot? Even with the first five successful launches, it seems there has been some scorching or singing of the mylar chute...which is why I became concerned and tried to replace a partially melted one with this unsuccessful yellow nylon. There's really no other reason for me to have tried the nylon...except the color matches the rocket...

Does anyone know what the size of the original Mylar chute included with the Mega Mosquito is/was? I have several Johnny E-Rocket Mylar chutes that I could cut to size, if it's an issue.

I wonder if I've just gone a bit to upscale on the chute for such a small(er) LPR rocket? Anyone got any suggestions for how to fold or wrap the nylon chute or wrap to protect it more from the gasses? It seems like the ejection charge is not blowing it out, but is discoloring and almost damaging the chute despite any Dog Barf or Recovery Wadding that I wrap it in. It would easily take four sheets to surround or enclose the chute in just one layer of this 'tissue paper'. Doesn't seem like it's doing its job...

As for removing the fin, I think with a little flexing, I could probably remove it completely from the slot, and give me best work-ability to repair it. it's cracked on both sides of the fillet now, so there's not much holding it in place any more. I'm loathe to do more to disturb the rear centering ring, as that appears to be still glued in tightly, and when I got the first suggestion to drill a hole to dribble glue down the root edges, it seems like introducing one flaw to try to repair another. So, I've not had an issue with the lack of glue until now. However, I'd be willing to try to resolve that.

Anyone have any opinion on Elmer's Yellow Carpenter Glue vs. Gorilla Glue... or I have an unused bottle of Tightbond drip-free glue available to me.

 

[ThirstyBarbarian]

If you can pull the one fin out, then before you glue it back into place, you can probably use the empty slot to fillet (or at least get some glue on) the other fins' internal joints. Try to get some glue wherever the fin tabs contact an internal surface --- motor tube, inside of body tube, centering rings. You might want to use a glue that is a bit liquid and can flow. Squirt it through the slot to either side, then hold the rocket at different angles to allow the glue to flow wherever you want it. If you have a syringe or other way to get glue exactly where your want it, use that. Then glue the fin back into the slot, being careful to glue ALL the joints.

 

[1tree]

I am going to guess that you do what I used to do. That is that the wadding and chute all push out the tube. I wanted the wadding to push the chute out. After too many failed deployments I changed course. Here is the thing, it isn't hot gases that produce the burn holes in your chute. It is burning particles that put those holes there. Keep in mind some use only baffles and no wadding.

Here is what works very well for me. I start by packing my chute so that it slips in the body very easy. If it takes less then half the tube diameter that is great. Next, if the chute attaches down the shock cord, I wrap the portion between the chute and the cone around the chute. I don't wrap shock cord from below the chute around my chute. I want the nosecone to drag the chute out with it.

Next I crumble my dog barf into small particles so it will pour out of the tube. I aim for two inches or twice the diameter of the tube whichever is more. And sometimes I put even more than that in. The idea here is to allow gas to easily pas through, but to make it thick enough to catch any and all particles.

Now there are plenty of people who still wrap their chute or streamer. And sometimes I do as well, mostly if I don't think I have enough dog barf. I built a Baby Bertha with a Mylar streamer and had to wrap the streamer with wadding because there just isn't enough length to get enough dog barf in there. I also cut open the nosecone so the streamer could be up there. Again, making sure it will simply fall out.

 

[Micromeister]

Kirk G:
Dog Barf just does not seal well. Over a lot of BT-80 and larger launches I've learned you really need to add an ejection plug of some sort. That can be something as simple as two sheets of plain old Estes FP Wadding below the Dog Barf. I usually Criss-Cross the sheets to form as complete a seal as possible. Slightly depress the wadding into the foreward end of the bodytube. Add you loosely fluffed Dog Barf and then a third sheet of estes PF Wadding on top while pressing the whole mess down into the bodytube. now load your shockcord, and chute wrapped with a single sheet of PF Wadding just in case.

Since switching to this technique with all my 3 & 4 D12 clusted Upscales I haven't had a single chute ejection problem.

While I don't use TTW fins very often I agree with Mushtangs rear centering ring removal as the best way to repair the fin problems.

 

[Kirk G]

If you can pull the one fin out, then before you glue it back into place, you can probably use the empty slot to fillet (or at least get some glue on) the other fins' internal joints. Try to get some glue wherever the fin tabs contact an internal surface --- motor tube, inside of body tube, centering rings. You might want to use a glue that is a bit liquid and can flow. Squirt it through the slot to either side, then hold the rocket at different angles to allow the glue to flow wherever you want it. If you have a syringe or other way to get glue exactly where your want it, use that. Then glue the fin back into the slot, being careful to glue ALL the joints.

To my great surprise, the wife came up with a syringe that she says was designed to suck up glue and inject or place it just as you describe. I'm not certain if Elmer's Yellow Wood Glue will suck up into it, but it's worth a try. If it won't draw in, then my next choice is going to be runny CA...("Houston, we have a problem"..... just kidding, since the fin is free, I'm goofing around with it backwards for a laugh...)

 

[Kirk G]

I am going to guess that you do what I used to do. That is that the wadding and chute all push out the tube. I wanted the wadding to push the chute out. After too many failed deployments I changed course. Here is the thing, it isn't hot gases that produce the burn holes in your chute. It is burning particles that put those holes there. Keep in mind some use only baffles and no wadding.

Here is what works very well for me. I start by packing my chute so that it slips in the body very easy. If it takes less then half the tube diameter that is great. Next, if the chute attaches down the shock cord, I wrap the portion between the chute and the cone around the chute. I don't wrap shock cord from below the chute around my chute. I want the nosecone to drag the chute out with it.

Next I crumble my dog barf into small particles so it will pour out of the tube. I aim for two inches or twice the diameter of the tube whichever is more. And sometimes I put even more than that in. The idea here is to allow gas to easily pas through, but to make it thick enough to catch any and all particles.

Now there are plenty of people who still wrap their chute or streamer. And sometimes I do as well, mostly if I don't think I have enough dog barf. I built a Baby Bertha with a Mylar streamer and had to wrap the streamer with wadding because there just isn't enough length to get enough dog barf in there. I also cut open the nosecone so the streamer could be up there. Again, making sure it will simply fall out.

Great suggestions. I'm working with a Mega Mosquito and have quite a large body tube to fill. I haven't tried that upper shock cord wrap yet, but I'm willing to try....once I get the fin glued back on...and that waits until after the fillets along the other two fins go in and dry. (Question: will glue fillets dry when inside a closed airspace with little or no outside vent (like through the remaining slot of the third fin))?

 

[RodRocket]

Is the chute even making it out of the body tube? Might try tying the chute closer to the nose cone, that way the cone will pull it out. And fluff the chute before you pack it to make sure it will open.

Estes has a 24mm retainer now. I put a retainer on my Mega when I built it and have launched it on F single use no problem.

Also some hardware store epoxy would fix up you fin nicely.