Qjet igniter retention

[4regt4]

Good afternoon, one and all.

I've had "issues" with igniter retention when using Qjets. Older ones had a plastic tube, which seemed to only fit a few select motors. On others, the tube is much smaller than the nozzle throat. It just drops in, and then falls right out when the rocket is upright. But for a few of the smaller motors (18mm), the tube is too big and won't fit.

So.. enter the Q-pic. I'm not having much better luck with that either. On one motor (may have been an E26, don't quite remember..) the pic simply falls in, right up to it's shoulder. And then falls out. In smaller motors, I can only get just the tip in, and it doesn't stay in place.

What I tried this last Saturday: On the suggestion of others here, I got some 3M poster putty. Put a small 1/8" ball of it in the nozzle of a D16-4, just like how we all did with toilet paper in old Estes motors. Pressed the launch button and POW. Blew the igniter and launch leads quite violently out. And the motor didn't ignite. Installed a new igniter, this time retaining with some masking tape. It worked, but it seems that the tape was burning and singed the Estes 24/18 adapter I was using across it's entire bottom surface.

I'm now wondering if I should try to see if any of the Estes plastic plugs will fit.

Hans.

 

[tfish]

Yes..it is a problem..especially since the Qjets need the igniter inserted and retained in a certain spot..this true with the A-C motors too. We've been using Duct Seal .clay from Hime Depot with good success..





Tony

 

[waltr]

On the Aerotech composite reloads there is a red plastic cap. The instruction say to cut of a corner to create an opening. What this does is prevent too much pressure inside the motor when the igniter fires but allow enough pressure to build to light the propellant.

Qjets would be the same. Don't completely seal the nozzle but hold the igniter in. I inset igniter all the way to the top of the propellant, bend the igniter lead up to the side of the motor and apply a piece of masking tape to hold the igniter. This has been working and the tape is not in the direct path of the motor exhaust.

 

[neil_w]

I started to have good luck with the little red tubes once I had the idea to cut them in half. At half length, I found it easy to insert them into the nozzle with the igniter. If having trouble, put the tube onto a toothpick and insert it that way, then remove the toothpick. I had a *lot* of trouble with the full-length red tubes.

I have some newer motors with the plastic inserts but haven't flown them yet.

 

[BEC]

Also pay attention to the color of the tube: yellow for White Lightning Bs (and maybe Fast Jack As and Bs), orange for White Lighting Cs and Ds, red for Fast Jack Cs and Ds and white for the 24mm motors. I believe (but have not yet seen) that there are two different Q-piks for the 18mm motors vs. the 24mm motors). This is not unlike the Estes plugs, which of course are color coded to go with the different nozzle diameters they support. And yes, even so, that heat shrink tubing can be frustrating. I've not yet actually gotten any motors with Q-piks.

I also second @neil_w's motion that cutting the tubing in half helps. It also helps, in my case, in dealing with early Q-jets that came with neither retention method.

Alternatively the old school "little ball of wadding" method works, too.

 

[4regt4]

Qjets would be the same. Don't completely seal the nozzle but hold the igniter in. I inset igniter all the way to the top of the propellant, bend the igniter lead up to the side of the motor and apply a piece of masking tape to hold the igniter. This has been working and the tape is not in the direct path of the motor exhaust.

I'm not quite sure how you are doing this. I'm often using the 18mm Qjets (usually D16 or D20) in an adapter. Are you taping the igniter to the surface of the clay nozzle? On the small motors, there is little room to do that, and almost no room when using the Estes adapter, which would trap the igniter leads if not hanging more or less straight down.

I have an ASP adapter that might be a little more friendly to this approach.

Hans.

 

[AeroTech]

This is the very first time I’m hearing anyone having an issue with the Q-Pics. It’s possible an 18mm Pic was included with the 24mm motor, or they were mixed up somehow. They are not interchangeable. We use them on a regular basis here during lot accept testing and don’t experience retention issues.

 

[4regt4]

I'll need to revisit using the Q-Pics. Perhaps I had some that were cross matched. Unfortunately, there is quite a bit of old inventory on dealer shelves, as I just received 6 packs of assorted Qjets and none have the Q-Pics. I'll also have to look about the ground (I do this anyway to pick up Estes plugs, etc...) to see if any used Q-Pics may be reusable in the packs containing the plastic tube.

Hans.

 

[AeroTech]

This should help. Orange for 18mm, red for 24mm.

 

[4regt4]

Thanks.

Yes, that's how I was doing it. I'm beginning to wonder if I had the smaller Q-pic included in a pack of 24mm motors, as I had the pic drop in all the way to it's shoulder.

Hans,