Certification Pass or Fail

[Alan15578]

There should be a timed contest: Completely disassemble a re-loadable motor, identify the assembly error, and reassemble it correctly. L3s should do it blindfolded.

 

[Buckeye]

NAR Very specifically says
Level 1 High Power Certification Candidate must assemble the reloadable motor, if used, in the presence of a Certification Team member.

I never understood this requirement. Nobody had to watch me glue the fins on the rocket. Building a motor, especially a cert motor, is something I would prefer to do in the comfort of home, not a windy, dirty field with somebody over my shoulder. Anyway this point is moot, given the proliferation of DMS motors.

Building a reload only takes a couple minutes, honestly, especially if you've built reloads for MPR rockets prior to your cert attempt. No reason to not use a reload, especially if the flyer plans on using RMS in the future, or has in the past. And the reloads are so much cheaper.

Yes and no. Most people probably build their first HPR motor slowly and carefully, especially if attempting to follow AeroTech's less-than-ideal instructions. HPR reloads are not identical to MPR reloads. For instance, the thin O-ring and thick O-ring may switch positions on the closures. That can trip you up.

Back in the day, yes, reloads were much cheaper than single use, and the ROI for hardware was pretty quick. Not so much today.

 

[John Kemker]

Yes and no. Most people probably build their first HPR motor slowly and carefully, especially if attempting to follow AeroTech's less-than-ideal instructions. HPR reloads are not identical to MPR reloads. For instance, the thin O-ring and thick O-ring may switch positions on the closures. That can trip you up.

This is why I strongly prefer snap-ring motors. They are straightforward, with little to no variation from motor to motor. You have one or more nozzle o-rings and one or more forward closure o-rings and maybe a few in the delay/smoke grain well.

 

[rcktnut]

HPR reloads are not identical to MPR reloads. For instance, the thin O-ring and thick O-ring may switch positions on the closures. That can trip you up.

These really help.
https://d11fdyfhxcs9cr.cloudfront.net/templates/170652/myimages/hprmsoring_1642635640668.pdfhttps://d11fdyfhxcs9cr.cloudfront.n...ring_spacer_insulator_guide_1642635744133.pdf

 

[loopy]

Yes and no. Most people probably build their first HPR motor slowly and carefully, especially if attempting to follow AeroTech's less-than-ideal instructions. HPR reloads are not identical to MPR reloads. For instance, the thin O-ring and thick O-ring may switch positions on the closures. That can trip you up.

Back in the day, yes, reloads were much cheaper than single use, and the ROI for hardware was pretty quick. Not so much today.

If you're building a 29/120 or 38/120 mid power load, they are identical to the HPR reloads. And the instructions are the reason you have someone watch you for your cert. And reloads are still cheaper, especially as you get bigger. For instance...a 75mm DMS M motor is $779.99...a 75mm RMS M motor is $376.99. It depends on what you're doing, I guess, but I much prefer the RMS, and find the instructions very simple to follow. I love that they include outlines of the parts with the names along the bottom of the sheet so you can easily know which o-ring is which (e.g. is the thick one forward or aft). Very easy to use, especially if you've done it once or twice before.

 

[loopy]

If the certifying flyer doesn't have experience with reloads, then imo they shouldn't use them.

I think a cert flight is the perfect time to learn to assemble a reload...You have to have your cert team there to watch anyway, so what better time to learn since you have an experienced flyer right there to guide and answer questions on your first one?

 

[KenECoyote]

I think a cert flight is the perfect time to learn to assemble a reload...You have to have your cert team there to watch anyway, so what better time to learn since you have an experienced flyer right there to guide and answer questions on your first one?

Great point!

 

[Buckeye]

If you're building a 29/120 or 38/120 mid power load, they are identical to the HPR reloads.

I mean the quintessential MPR Hobbyline reloads - the 24/40 and 29/40-120. They are not the same as HPR.

And reloads are still cheaper, especially as you get bigger. For instance...a 75mm DMS M motor is $779.99...a 75mm RMS M motor is $376.99.

Maybe for L3 motors, but we are talking about first-time HPR users here. The poster mentioned the H135 DMS ($46.99). A reload with similar impulse is the H180 for $41.99 plus motor hardware for $119.99. Looking strictly at dollars, the ROI for the hardware investment sucks.

 

[-Slick-Ice]

On the 29/38mm reloads the ROI for a case is pretty quick if you need to pay hazmat on a DMS.
I will be honest the first time I used a 29mm reaload I still wasn't sure what way to put the delay in even after reading the directions like 4 times.

 

[tsmith1315]

On the 29/38mm reloads the ROI for a case is pretty quick if you need to pay hazmat on a DMS.

Great point!

 

[loopy]

I mean the quintessential MPR Hobbyline reloads - the 24/40 and 29/40-120. They are not the same as HPR.



Maybe for L3 motors, but we are talking about first-time HPR users here. The poster mentioned the H135 DMS ($46.99). A reload with similar impulse is the H180 for $41.99 plus motor hardware for $119.99. Looking strictly at dollars, the ROI for the hardware investment sucks.

Not the same, but still very similar if we're being honest. And I would say the ROI is very good if you're using spacers...it's not like when I started in HPR, and you needed to buy every available case size as there were no spacers. Factor hazmat shipping in (as many smaller HPR loads can ship without hazmat as opposed to the corresponding DMS motor), and it's a great ROI.

 

[-Slick-Ice]

The biggest reason I started using the 29mm reload and adapter system is because the .7g of bp in the g80 was not enough for most of my 3" rockets.

 

[waltr]

The biggest reason I started using the 29mm reload and adapter system is because the .7g of bp in the g80 was not enough for most of my 3" rockets.

Yep, I've gone from the 29/40-120 reloads to the 29/120 reloads for the same reason, can't get enough BP in the ejection for a 4" diameter rocket.

 

[jmasterj]

Yep, I've gone from the 29/40-120 reloads to the 29/120 reloads for the same reason, can't get enough BP in the ejection for a 4" diameter rocket.

You can always add more. I've not had problems with 4" rockets on Hobbyline G loads.

 

[T-Rex]

I think having a cert mentor beside someone building their first reload would be one of the best times to start using reloads. Would seem less likely to fail and create a hazard or a damaged rocket.

I was thankful to have a mentor observing my L1 reload assembly. I was quite nervous and forgot to drill the delay. The mentor (a man I hand met maybe 30 minutes prior as I was visiting an out of town launch) asked me if I needed to drill the delay just before final assembly. He allowed me to learn from my mistake by waiting to ask.
I have a DMS for L2, but I am rethinking that, I have a 38/720 and a 54/1280 case, plenty of motors between them that fit my needs better as I need to add a few grams of BP for a safe ejection. (Assuming I actually fly my L2. Rethinking that as well)

 

[Buckeye]

And I would say the ROI is very good if you're using spacers...it's not like when I started in HPR, and you needed to buy every available case size as there were no spacers.

I will belabor the point. Spacers are not improving your ROI vs. DMS. They are more hardware, so your ROI gets worse. The problem is that reloads are damn near the same price as a DMS:

620 N-s 38mm DMS I500 = $96.99
597 N-s 38mm RMS I600 = $89.99
38/720 Motor = $134.99

One would have to fly about 20 reloads to finally break even on the upfront motor hardware purchase vs. DMS. 24 flights needed on the H motor example I posted above. That's pretty daunting for a newbie L1. Back in the day (10-20 years ago) when I bought my L1 hardware, the payoff was something like 5 flights.

Yes, there are reasons to buy reloadables (the enjoyment of assembly, different propellant colors, etc), but the cost per impulse is not one of them unless you plan to fly a lot (and not lose your rockets).

Factor hazmat shipping in (as many smaller HPR loads can ship without hazmat as opposed to the corresponding DMS motor), and it's a great ROI.

True, but I would hope that people buy several motors at a time to spread the cost of shipping and hazmat. Plus, shipping and hazmat can be avoided. There is no avoiding the reality that H and I reloads are only $5-$7 less costly than equivalent DMS motors and require a couple hundred bucks of hardware.

 

[tsmith1315]

True, but I would hope that people buy several motors at a time to spread the cost of shipping and hazmat

The majority of flyers probably do, but not everyone is in that position.

It's strictly one or two at a time here, and only non-hazmat for shipping. I see that charge as another H-motor that I'm giving up. Anything hazmat is purchased on site.

edit: I purchased a used 38/1080 case not long ago so I would have at least one J-motor available for shipping without hazmat. I figured that was pretty close to the additional shipping charge had I bought a regular J-motor. And I can get my money back out of it if needed.

 

[loopy]

I will belabor the point. Spacers are not improving your ROI vs. DMS. They are more hardware, so your ROI gets worse. The problem is that reloads are damn near the same price as a DMS:

620 N-s 38mm DMS I500 = $96.99
597 N-s 38mm RMS I600 = $89.99
38/720 Motor = $134.99

One would have to fly about 20 reloads to finally break even on the upfront motor hardware purchase vs. DMS. 24 flights needed on the H motor example I posted above. That's pretty daunting for a newbie L1. Back in the day (10-20 years ago) when I bought my L1 hardware, the payoff was something like 5 flights.

Yes, there are reasons to buy reloadables (the enjoyment of assembly, different propellant colors, etc), but the cost per impulse is not one of them unless you plan to fly a lot (and not lose your rockets).



True, but I would hope that people buy several motors at a time to spread the cost of shipping and hazmat. Plus, shipping and hazmat can be avoided. There is no avoiding the reality that H and I reloads are only $5-$7 less costly than equivalent DMS motors and require a couple hundred bucks of hardware.

Not everyone is able to buy a large quantity of motors all at once, and not everyone is lucky enough to have an onsite vendor at launches, or to live close enough to a vendor to avoid hazmat.

Is the ROI the same as it was? No, of course not. But even at 24 flights, it's still worth it in the long run for anyone looking to remain in the hobby for more than a couple of years. Especially if you can buy the hardware used at a cheaper price.

 

[Orestes Mayo]

It's probably a good idea to fly a cert rocket on motors just below the line a couple times before going for the cert. i.e., if you're going to cert with a baby or modest H, fly a G80 or two before putting that H in it. Make sure you've got multiple nominal flights on the bird before the "big show." Not just working once, but working consistently. With your prep procedures and accompanying check list dialed in.

Thanks for the advice. That's exactly what i have been doing with my Loc4. Used a G75M and G80 tomorrow. Also has helped me calibrate the Sim. The Cd is always something to look at.

 

[SolarYellow]

I bought most of my hardware used or on the best sales I can find, and I can sell it used, so the cost of ownership will be low.

 

[bobbyg23]

The intention is that the bolts fail before the fins do. It worked as intended.

The LOC IV fins are only 1/8 inch ply. It is surprising that this kit is highly recommended for Level 1 certs. The bolt-on arrangement was my modification to protect the fins.

Why is that surprising? If you have an appropriate sized chute that deploys then 1/8" fins are just fine. Many people have survived flights with those fins!

 

[-Slick-Ice]

The 5.5 IROC has 1/8" fins and it takes a beating.

 

[OzHybrid]

I bought my G64 reloads for Au$25 I could currently sell them for Au$100. They're unobtanium in Australia...... If you see what you'll use at a good price and you intend to stay in the hobby, borrow the money to buy them...... That would be a 400% return on my investment.......