Pratt Hobbies GOX Box recall

From news I got from Plaster Blaster, I may have sent out five RTLS-M4 GOX Box units with inferior or defective high voltage transformers. I have sent individual emails to recent customers, but I want to make sure I catch all of these.

If you have an RTLS-M4 GOX Box, please look at the wires that connect to the igniter wire. If they have black insulation, you're fine. If they have white insulation, please send the GOX Box back to me for a free replacement. I have also upgraded the internal relay, and will supply you with a new unit that has all the latest "lessons learned" incorporated in it.

Doug Pratt

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Reply to
Doug Pratt
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So YOU are why Ray's sensational photo only has 5-6 rockets instead of

12 :)

On a serious note, isn't there a way to test this equipment in its final form before release? It is pretty complex and high power. Maybe some sort of test apparatus would be a good investment.

I am glad it is you that is supporting hybrids and not me. God job generally.

Jerry

Solids bigot

Reply to
Jerry Irvine

I know you're kidding Jerry, but not all the failures were due to ignition issues. I know for a fact that Paul, who was right next to Ken's pad, had a leak due to a second 0-ring forward of the injector. It filled for about a minute, then the pressure got by the mash of O-ring so it wasn't caught during the 5 second burst during pre-flight.

There were also 3 or 4 RF units in use and it's possible that one failure was due to an operational issue, or because the other transmitters had more power.

I wonder how many of the 5 units were at PB. West coast support has generally come from Wayne of

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was out on the flight line helping out. I know I've had great service from both vendors.

While no one wants to see a failre of the GSE, it's great the vendor is on top of this one.

I'm not quite sure what the issue was with the igniter box, but it simply connects to speaker wire and an arc forms across the ends when you punch the 'fire' button. Simple enough test. It could be that if you mash it for

5-10 seconds it over heats or some such and that may not have been thought about. The fill solenoids are great for J-K tanks, but they were finding that in the heat and extra fill time of L-M tanks (3+ minutes), the solenoids would fuse (they're designed for race car 1 second bursts). I don't believe that was found in production testing either.

^^^

Geee, I thought YOU were up for that position.

Oh yes,... 'rocket science'. Insert motor and push button,... "ugh me make fire". ;)

Joel. phx

Reply to
Joel Corwith

I dont think Doug uses the race car version of the solenoids. He has his own made.

I have Hybrid GSE that I built, at some point I will have to make a page that shows how I built it. It uses a circuit that limits the current to the solenoid after it opens, this keeps them cool and they can run for hours( I suppose). Works great with the auto solenoids I got off Ebay.

RDH8

Reply to
Robert DeHate

I suspect that as solids volume ramps up there will be a trickle of support for USR branded hybrids as usual. Then I will be forced to address the issue of releasing my own GSE (which is more expensive because it uses high duty solenoids) or just go with the flow on GSE and maybe co-invest in somebody's operation to encourage higher quality parts on one-time purchases like GSE. A company who can afford to give raffle prizes to Tripoi despite being banned for 12 years certainly can afford to give every solenoid away free on every GSE system ever delivered (not many).

Don't forget to say "ugh" really loudly and in a hoarse voice. Helps to be dragging a woman or two by the hair.

Jerry

Reply to
Jerry Irvine

High duty solenoids? Does this help with filling times? ( has higher flow) Or is this to help with overheating due to long open times?

The latter can be cured by using a solenoid driver. Instead of the typical on/off controllers that are typically used.

RDH8

Reply to
Robert DeHate

HEY! I resemble that remark. i'm in the same boat....hybrids just seems way to complex and fail way too often to be any fun.

-Darren

Reply to
Darren Wright

Yes, I was refering to the standard Hypertek GSE which uses auto solenoids (NOS #16000 for fill), not Doug's made for staying open ones.

Joel. phx

Cap and resistor?

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Reply to
Joel Corwith

Larger solenoids can supply more nitrous, reducing fill time. They have larger openings, thus stronger springs to hold the rod against the port. Therefore, the field needs more pull. But then you are limited by your fittings, hoses, and the fill stem (ultimately the holes in the fill tube). I don't think #6 would be out of line for connections.

Even if you halved an M fill, that would be 1 1/2 - 2 minutes, still a bit more than the 1-3 second burst in auto racing.

Joel. phx

Reply to
Joel Corwith

That's funny, I was thinking the same thing as I watched a L3 cert attempt with AP (1/6 scale V2 from SkunkWorks). I have a clear video of the rocket lifting off to about 30' and the flight of the motor out the nose, impacting

20' from where we were standing. It proceeded to burn out both ends, leaving the casing oval and threads smooth.

That was a lot of Fun at 4x the cost of Hypertek launch.

Joel. phx

Reply to
Joel Corwith

Now you've gone and stepped in it...

Reply to
Kurt Kesler

I have heard people say that about electronics too. It's not complex & failing, its exciting and challenging.

RDH8

Reply to
Robert DeHate

A defective motor should be replaced.

Reply to
Jerry Irvine

Nope, I use a solenoid driver it a DRV-101

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I added a MOSFET to the output so it could easily handle the current required by the solenoid. Go figure I used a 'REAL' solenoid driver. One resistor sets the duty cycle used after the time out and one capacitor sets the time the solenoid gets full power.

The output of one of my Roctronics units just switches it on/off and the driver does the rest.

I will have to make a web page for it.

RDH8

Reply to
Robert DeHate

#3

I will keep that in mind. Thanks.

Reply to
Jerry Irvine

It may have landed 20 feet from you; JD and I were a lot closer. One nice thing about a hybrid motor is that when one comes apart, the fire goes out. I'd much rather face a failed hybrid spraying nitrous than a failed AP motor spraying flame and burning chunks.

Reply to
Ken Sparks

Bzzzt. I saw a L hybrid fail by spitting the end closure and nozzle. The motor went through the rocket and then continued on a parabolic arc, burning for a LONG time. Burned until it was out of sight a long way downrange (and off the field).

Therefore hybrids are not only a pain in the rear, they are downright dangerous and should be heavily regulated.

(or you hybrid guys could lighten up a bit ;-)

Reply to
Kurt Kesler

I'm bad at distances. I don't think it went up 30' either. We can watch the video this weekend, I'll have to do some editing.

If you recall the shortened Tomahawk that went all the way up to the top of the rail under nitrous pressure managed to keep burning after setting down next to the pad (now I WISH I had that one on video).

Joel. phx

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Reply to
Joel Corwith

Hey, thanks for the link. There's a freakin chip for everything now a days, isn't there?

Joel. phx

Reply to
Joel Corwith

BOY,... I get a dig in at Jerry (solids bigot), and THIS is the thanks I get?!

:)

Joel. phx

Reply to
Joel Corwith

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