Failed L1

[askrob]

On Sunday I attempted to recertify myself as level 1. 20 years ago, I had certified L1, so I figured it would be easy to do it again. I decided that instead of launching the PML mini-black brant I previously certified on, I would build a new rocket. My justification was that after 20 years, I had lost skills and wanted to relearn. I chose a PML Tethys, so that I could get my L1 and L2, potentially on the same day, or so I thought.

I modified the rocket a bit, adding an eggfinder in the nose and foaming around the motor mount. I realized when I painted the rocket, you can see the before photos in my other posts, that the nose cone took a lot of effort to come off. I was worried about that, but had convinced myself that it would be fine. Well, all was not fine. I launched, it flew beautifully, but the nose cone never came off. It lawn darted.

After I collected all the pieces, the wind started to pick up. Not too high, but certainly noticeable. As I brought the pieces back, I mentioned I had my PML mini-black brant sitting in the car. Use that to certify! I made sure it would separate fine, got another motor, and launched! It went well! Flight was perfect, ejection was timed perfectly, but remember I mentioned the wind? That wind was my nemesis. It took my rocket. We searched through 2 miles of fields and didn't find it. I'll have to venture back out to see if I can find it.

Here's the results of my Tethy's. I am certainly going to try again to certify. I learned a lot in building this, and even with the failure, it exposed some weaknesses in my build process.

 

[o1d_dude]

Rough day.

Karma decided against you.

Hopefully the Eggfinder in the nose cone survived.

 

[askrob]

Rough day.

Karma decided against you.

Hopefully the Eggfinder in the nose cone survived.

The GPS module broke, but I'm hoping the rest of the circuit board is fine. It looks to be. I don't have a hot air rework station to remove the gps module properly, but if I can replace the gps module it's possibly going to work again.

 

[XrayLizard]

Sorry to hear ! Looks like shorten the tube and your good to go ?

 

[askrob]

Sorry to hear ! Looks like shorten the tube and your good to go ?

A fin came off and the top centering ring came out, but all that should be fixable. Oh, and the PML Kwick Switch busted, so can't run 29mm or 38mm using that system anymore. Maybe there's another way to adapt down from a 54mm. Got a new project though!

 

[askrob]

Would anyone be willing to fix my eggfinder? I currently don't have a hot air rework station to properly remove the broken GPS module. I will need to get a new GPS module.

 

[Fattbank64]

You're one step closer to success. They call it tomorrow for a reason.

 

[C.O.B.H.C.]

I would recommending get the AeroPack Flanged 54mm motor retainer (https://aeropack.net/webstore/product.asp?productid=332369740757234) and the two adapters the 54 to 38 and the 38 to 29 you can nest them together to adapt down from 54mm to 29mm.
54mm to 38mm adapter (https://aeropack.net/webstore/product.asp?productid=85)
38mm to 29mm adapter (https://aeropack.net/webstore/product.asp?productid=84)

 

[KilroySmith]

Would anyone be willing to fix my eggfinder? I currently don't have a hot air rework station to properly remove the broken GPS module. I will need to get a new GPS module.

I'd be willing to help out if you can't find anyone else - I'm only moderately good at SMD soldering (haven't picked up the wrong end of the soldering iron in a few years), but do have a hot air station, and an eggfinder of my own. Chris might be able to provide you with a replacement module...

Taking a look at your pictures, it looks like the GPS Antenna is simply glued onto the package, with a single central wire leading down. Perhaps it only needs that wire repaired?

 

[Michael L]

Would anyone be willing to fix my eggfinder? I currently don't have a hot air rework station to properly remove the broken GPS module. I will need to get a new GPS module.

I've got a hot air rework station. I'd be willing to remove the old one for you and send the board back. Cris can probably supply the antenna.

 

[askrob]

I'd be willing to help out if you can't find anyone else - I'm only moderately good at SMD soldering (haven't picked up the wrong end of the soldering iron in a few years), but do have a hot air station, and an eggfinder of my own. Chris might be able to provide you with a replacement module...

Taking a look at your pictures, it looks like the GPS Antenna is simply glued onto the package, with a single central wire leading down. Perhaps it only needs that wire repaired?

thanks for the willingness to help. Mike, next comment, is going to help me.

 

[spigalau]

When you rebuild the eggfinder, use the instruction from the 'mini' which says to epoxy around the GPS antenna.

 

[askrob]

When you rebuild the eggfinder, use the instruction from the 'mini' which says to epoxy around the GPS antenna.

was not aware of that! Great suggestion!

 

[OverTheTop]

When you rebuild the eggfinder, use the instruction from the 'mini' which says to epoxy around the GPS antenna.

Absolutely. The patch antenna is only usually held on by double-sided tape and a single wire soldered in the middle.

 

[spigalau]

was not aware of that! Great suggestion!

From the Manual:

Shockproofing Your Eggfinder Mini

The Eggfinder Mini is small and light and can take quite a beatingfrom things like hard landings and VMax motors, however there is one component that is vulnerable... the GPS antenna, that brown square on top of the module. We STRONGLY recommend that you glue it down to the metal shield using a thin bead of a high-quality non-conductive epoxy like RocketPoxy or West Systems. Don’t use the cheap hardware store epoxy, and DO NOT use JB Weld...it contains metal particles andcan detune theGPS antenna and reduce its performance. It doesn’t take much, a couple of drops of epoxy spread between the base of the antenna and the shield should do it. Try not to get it on the solder pads, in case you have to resolder them at some point later on (not likely, but not unheard of either).

The kit includes some clear heatshrink tubing, this is to cover the GPS module’s exposed pads (those channels on the side that were so much fun to solder...) to protect them from abrasion if you decide to put it in a pouch of some sort in your body tube. Slide it over the board so that it goes from the antenna side of the board to just past the GPS module, then shrink it in place with a heat gun on LOW. You want to do this AFTER your epoxy cures... typically the next day.

We also recommend that if you’re putting your Eggfinder Mini in a pouch that you zip-tie the power wires to the unused screw mount at the back of the board, and use some kind of soft adhesive (such as RTV silicone or hot melt glue) to tack the wires to the pads so they won’t get bent and break off due to stress.

 

[K'Tesh]

I didn't pass my L1 on my first attempt. I hope you recover the lost one, and can get your cert.

Pointy Side Up!!!