Rookie HPR mistakes

[Grog6]

'You've managed to do one of the things that make you go Doh!
Nothing quite like seeing the large, Orange tag that readably says "remove before flight".
A buddy asked me "What's the tag?"
It says "recovery system is not armed." Lol.

 

[thobin]

Using a non welded or forged eye bolt. That's a mistake you will only do once!

TA

 

[Pem Tech]

My favorite Rookie mistake was "After joining an R&d group at a major medical company, I was building test equipment to make Gamma detectors that could be near an MR.
I left a working piece of equipment we wanted to use, along with some huge power supplies on a cart, with a sign saying !!this can't be in the MRroom!!
On it, running, on a 30 ft extension cord. The other guys were at lunch. So, I set everything up, and go to lunch.
I return from lunch, to them prying the cart out of the bore of the mr, and the powersupplies were a smoking mess, lol.
I learned two things: Switching power supplies don't work in a 3 Tesla magnetic field, and PhD's don't read signs.

A non-magnetic gamma counters? Intriguing...
Tell me more.
We used the good ole' Ludlum Geiger Müller counters, models 3 and 14 I believe.

 

[Grog6]

A non-magnetic gamma counters? Intriguing...
Tell me more.
We used the good ole' Ludlum Geiger Müller counters, models 3 and 14 I believe.

We made two different MR compatible PET scanners,one a dedicated brain scanner, and one whole body. Millions of counts/ sec,digitized and timestamped to picoseconds. Mostly 511keVgammas from f-18.
You overlay the data, and cancer shows up highlighted by the tracer used.

 

[Grog6]

We used Si APD's, or Avalanche Photodiodes, running about 500V.
Photomultiplier tubes do not work in a strong magnetic field, a property shared by all vacuum tubes.
The new replacement is way better; we got Linear Tech to make us a high voltage opamp. And Analog Devices.

 

[OverTheTop]

Photomultiplier tubes do not work in a strong magnetic field, a property shared by all vacuum tubes.

We have looked at using Si APDs as well. We don't have a magnetic field problem so it is hard to go past the performance of PMTs. We get good linearity and noise performance over 200 dB dynamic range (1 to 10000 million scaling). APDs are worth a look though. Been thinking of doing a modern version of a geiger counter using one. I built a geiger counter with a GM tube back in 1981 so maybe a more modern version is warranted.

 

[Grog6]

PMTs are a near perfect amplifier, with a gain of about a million. The apds we used were a gain of 200, and required a slow charge sensitive preamp. SiPM technology is there now; much higher gains than apds at lower bias voltages..
I have a collection of PMT's and other devices that photonis or hamamatsu was nice enough to give me.I have a nuclear spectrography setup with tennelec aPCA3 data card to do analysis.
I'm
looking for a scintillator that is sensitive to neutrons.

 

[Grog6]

Oh, if anyone is interested in geiger detectors, gold mine electronics sell tubes and kits.

 

[Michael L]

The Electronic Goldmine... those people have cost me some. One day my kids will sort through the parts and wonder what the hell? I tell them to put that stuff on eBay. Someone will want it. Preferably that happens far into the future.

 

[Arsenal78]

I made the rookie mistake on my first L2 attempt of thinking 15 year old nylon from an original BSD Thor kit was still safe to use. I didn't know tubular nylon still protected and sealed would still have a shelf life.

 

[FlyBy01]

I made the rookie mistake on my first L2 attempt of thinking 15 year old nylon from an original BSD Thor kit was still safe to use. I didn't know tubular nylon still protected and sealed would still have a shelf life.

Ouch

 

[ThikeHigh]

I’m using a single use store bought motor for my L1 flight. Using a Apogee Zephyr with engine being chosen for least amount of altitude to keep it simple. And for my L2, I won’t dual deploy until after certified. Then mistakes will be fewer and not be stress induced.

 

[Orien]

I’m using a single use store bought motor for my L1 flight. Using a Apogee Zephyr with engine being chosen for least amount of altitude to keep it simple. And for my L2, I won’t dual deploy until after certified. Then mistakes will be fewer and not be stress induced.

Yeah, that "low and slow" philosophy can be problematic. I watched a cert 1 flight with this very rocket on an H100 take off slow, then it leaned over to about 45 degrees right after it left the rail and did a field goal over the power lines into the deep brush never to be seen again.

 

[John Taylor]

I’m using a single use store bought motor for my L1 flight. Using a Apogee Zephyr with engine being chosen for least amount of altitude to keep it simple. And for my L2, I won’t dual deploy until after certified. Then mistakes will be fewer and not be stress induced.

How are you determining which motor to cchoose? If you used a simulation program your probably good to go.
If not try Thrustcurve.org. I use it everyday. It's easy free and fun.

 

[John Taylor]

Problem with epoxy is it becomes brittle over time

Mike

How much time?
I stored all my HP rockets in my attic in Texas for 17 years thinking I would never fly again. Pulled them out 2 years ago and they are holding up to big motors and seem fine.
Inspecting the epoxy joints I can access I cannot find any issues.

 

[thzero]

I’m using a single use store bought motor for my L1 flight. Using a Apogee Zephyr with engine being chosen for least amount of altitude to keep it simple. And for my L2, I won’t dual deploy until after certified. Then mistakes will be fewer and not be stress induced.

If you've had plenty of F and G experience with our without rebuilds then the first H flight should be none event

 

[Steinerino]

Here is an interesting mistake. After flying successfully on a J motor with chute release, I wanted to test out electronics -- using RRC2 - simple. Ground tested the charge - optimized the charge. Loaded up camera, JL altimeter and the chute release. Set the charge for +1 second after apogee. Drilled out delay per Rocsim recommendation.

Here is what I believe happened. Successful launch to ~5K feet, motor ejection releasing chute held by JLCR. Then the charge goes off and blows off the JLCR -- releasing the chute at 5K feet. The chute was attached about 2-3 feet from the charge/ebay - so this is speculation.

Result: The 5 foot candy apple red rocket was not seen again after miles of searching. ...enter the Linda Ronstadt song - 'Somewhere Out There'.....

 

[ThikeHigh]

OUCH, I think that is why I am saving up for an Eggitimer GPS with the direction arrow feature added. I just hope that it won't fly out of range of the signal. We launch on a 25-acre area up in a mountain ranch at 9,000 feet above sea level. The thin air is great to fly in when the wind is not too strong.

Good Luck and thank you for the post.

 

[DaHabes]

Here is an interesting mistake. After flying successfully on a J motor with chute release, I wanted to test out electronics -- using RRC2 - simple. Ground tested the charge - optimized the charge. Loaded up camera, JL altimeter and the chute release. Set the charge for +1 second after apogee. Drilled out delay per Rocsim recommendation.

Here is what I believe happened. Successful launch to ~5K feet, motor ejection releasing chute held by JLCR. Then the charge goes off and blows off the JLCR -- releasing the chute at 5K feet. The chute was attached about 2-3 feet from the charge/ebay - so this is speculation.

Result: The 5 foot candy apple red rocket was not seen again after miles of searching. ...enter the Linda Ronstadt song - 'Somewhere Out There'.....

The mistake was drilling out the motor delay too much. You want the electronics to eject at apogee (not +1 seconds) and use the motor eject as the backup to the altimeter. The motor should be drilled out to 1-2+ seconds after apogee.

 

[maverickrocketry]

been there done that.

 

[JackC]

Flying an all white rocket without a radio tracker and watching it disappear behind hundreds of sagebrush on a snow-covered field in October.
Didn’t get it back until June the next year.

 

[JackC]

How much time?
I stored all my HP rockets in my attic in Texas for 17 years thinking I would never fly again. Pulled them out 2 years ago and they are holding up to big motors and seem fine.
Inspecting the epoxy joints I can access I cannot find any issues.

I had the epoxy joint fail on a Hawk Mountain Transonic II at the bulkhead on the aft section of the altimeter bay. The epoxy was placed there by the kit manufacturer 15 years ago. Now I check the joints for any rocket that’s more than ten years old.

 

[Citizen Baslim]

Flying an all white rocket without a radio tracker and watching it disappear behind hundreds of sagebrush on a snow-covered field in October.
Didn’t get it back until June the next year.

Hence my preferred colors are always fluorescent

 

[Greg Furtman]

Hence my preferred colors are always fluorescent

All my parachutes are fluorescent colors. Hot pink is the easiest for me to see.

 

[JackC]

Hence my preferred colors are always fluorescent

It’s a scale model Nike Smoke.

 

[dhbarr]

All my parachutes are fluorescent colors. Hot pink is the easiest for me to see.

I like hazard orange and then wearing vermillion shooting glasses to cut out dust/water haze.

Disclaimer: reddish/pinkish glasses don't bother me, YMMV.

 

[AndrewGil]

Managed to glue the motor tube into the body tube and did not attach the shock cord. Managed to thread some small steel wire into the eyebolt and reverse thread the shock cord in there and used a slip knot (not the best, but better than nothing) to attach it.

 

[Citizen Baslim]

It’s a scale model Nike Smoke.

They didn't paint Nike Smoke in fluorescent colors?

 

[Titan II]

They didn't paint Nike Smoke in fluorescent colors?

https://www.rocketryforum.com/threads/nike-smoke-color.108697/

 

[mrwalsh85]

Managed to glue the motor tube into the body tube and did not attach the shock cord. Managed to thread some small steel wire into the eyebolt and reverse thread the shock cord in there and used a slip knot (not the best, but better than nothing) to attach it.

Threaded Plugged Forward closures are your friend...