Reliability

[bill_s]

What is the relative reliabilty of the various motors, especially in the MPR range? Not just brands, but reloadable vs. single use.

Have had my share of bad luck with Aerotech SUs, never personally had a problem with regular Estes. I see CTI reloads in the smaller sizes are basically the price of Aerotech single use, but it could be worth it to me for improved reliability. Same thing goes for Aerotech RMS, the reloads are cheap but it looks like about 9 flights are needed to break even over SU?

Economy is big with me, but my biggest rocket took over a a month to build ....

 

[MarkII]

Certified motors should all be reliable. (That's one of the tests that a motor must pass in order to be certified.) That doesn't guarantee that every single one will be perfect, but defective motors are rare. (I have never had one myself in 12 years in the hobby.) If they were any more frequent, the manufacturer would withdraw them from the market.

I have burned motors from Estes, Quest, AeroTech and CTI, and in 12 years I have never encountered a problem with any low power, mid power or high power reload or SU motor that I have ever used.

 

[cjl]

For what it's worth, I've seen more failures of SU motors than reloads - in the mid power size range, I haven't seen any real problems with AT or CTI reloads, but I have seen a few problems with AT SU motors. That having been said, I can't say I've been keeping track of the statistics or anything, so it could be a mistaken impression. Personally, I only fly reloads, and I haven't had any trouble with them.

If you're mainly flying mid power, I would say that one of the best investments you could make would be an AT 29/40-120 casing. It holds a really nice variety of inexpensive E-G reloads, and it pays for itself relatively quickly. In my opinion, everyone who flies any significant amount of mid power should have this casing - there are just so many nice motors for it, and it's perhaps the least expensive choice per flight in mid power.

 

[MarkII]

A build taking one month from start to finish would qualify as a quick one for me.

 

[MarkII]

For what it's worth, I've seen more failures of SU motors than reloads - in the mid power size range, I haven't seen any real problems with AT or CTI reloads, but I have seen a few problems with AT SU motors. That having been said, I can't say I've been keeping track of the statistics or anything, so it could be a mistaken impression. Personally, I only fly reloads, and I haven't had any trouble with them.

If you're mainly flying mid power, I would say that one of the best investments you could make would be an AT 29/40-120 casing. It holds a really nice variety of inexpensive E-G reloads, and it pays for itself relatively quickly. In my opinion, everyone who flies any significant amount of mid power should have this casing - there are just so many nice motors for it, and it's perhaps the least expensive choice per flight in mid power.

And then your second reloadable motor should be the AeroTech 24/40, which also has a decent variety of reloads for it. Among all of my mid power motors (from 24mm to 38mm), this one seems to get the most use, but my 29/40-120 is also mighty handy too. Shop around -- you can find a range of prices for these motors, including pretty good ones.

 

[RWmarlow]

Sometimes things happen....over the years these were some I had one or more issues with.... FSI E 60 (Never CATO'ed an F100), MPC B3-3 (18mm),Estes D13 24mm (cooked two
COX Saturns ) Estes E15, and the NCR/Estes F62, but all in all (since I built my first rocket in 1967) the success rate is such that I haven't quit yet !:wink:

 

[sodmeister]

I used to fly mainly Aerotech S/U motors from E to G for over 10 years (and I still do fly AT S/U motors from time to time) and can only think of 4-5 motor failures in that time ,and we are talking quite a few motors ,so I count that as very reliable.

I now mainly use 100% CTI reloads for all my HP and 90% of my MP ,and have not yet had a motor failure.

For all my LP, I have always used Estes and recently Quest black powder motors ( back in the 70`s and again as a BAR staring in 2000) and can`t recall of any motor failures.

I think the way motors ,S/U or reloads ,are handled and stored plays an important role in motor reliability.


Paul T

 

[bill_s]

I'm wondering/hoping if maybe I could have used up my bad luck for a while ... "Lemons Never Lie" ....

And then your second reloadable motor should be the AeroTech 24/40, which also has a decent variety of reloads for it.

That you're trying to talk me into a second case already doesn't exactly convince me ... although it would help justify the drilling tool :dark: . Also my 24mm-only rockets will be flying high and drifting far when they get the occasional F.

I really don't know how far I'm going with this rocketry hobby any further than the next launch, but then if I have any more motor problems that could be it.

BTW, with RMS is it possible to reduce the ejection charge? The 24 mm charges are ridiculously overpowered enough for rear ejection, yet 29 mm is really the right power range.

 

[cjl]

Yes, with the reloads, you can put in however much powder you want for the ejection charge.

 

[GDJ]

Well, myself and Pat H. have never had a CATO with any Aerotech motor so far.

Pat had a CATO on a Estes E9 2 months ago......I think my last CATO motors were the old Canaroc motors from the early 1980's.......

 

[blackbrandt]

Yes, with the reloads, you can put in however much powder you want for the ejection charge.

To a limit. You can't cram a pound of 4F into a 24-40 reload...
Also, you can add powder to a SU motor. Just pour it into the Forward closure and seal it with tape.

 

[cwbullet]

I have had one cato with CTI and 2 with Aerotech. I have never had on with Estes.

 

[qquake2k]

The only issues I've ever had with AT SU motors is ignition failure. I've had a few of the same issues with reloads, too. But they were all with Copperhead igniters. A couple of observations about using Copperheads.

1) They're current hogs! Even with the club equipment sometimes there's not enough current available to get a good ignition with them.

2) Sometimes the heads of Copperheads are a little big. This can make it difficult (or impossible) to get the igniter fully into the motor. Keep in mind, that AP motors burn from the top down, unlike BP motors. So the igniter has to be all the way to the top of the grain to get good ignition.

I too will recommend reloads, because:
A) I really wish I'd started using them sooner than I did.
B) They really are less expensive in the long run.
C) There are motor choices you can't get with SU.
D) You have more control over the delay times (with the drilling device).
E) It's easier to put the igniters in as you assemble the motor.
F) They're fun!
G) This hobby is addicting. Might as well give in now and start enjoying the benefits of reloads right away!

 

[JPVegh]

I've experienced a few chuffs with AT motors but they all eventually fired up and launched. The only serious issues I've had with AT motors is the occasional bonus delay that resulted in some scary recoveries.

I have had more problems with black powder motors. Estes E15s destroyed the majority of my large Estes rockets over the course of one season. I had a D12 detonate on the pad destroying a cluster rocket. More recently an A10 destroyed a contest rocket that I was testing. Given the large number of Estes motors that I've launched over the past 40 years the failure rate is quite low in comparison.

Generally rocket motors are quite reliable and I never think when I push the launch button that it will do anything other than what it's supposed to.

I love my RMS motors, the selection and price are a big advantage over SU motors and I actually enjoy assembling them.

 

[Jeroen_at_CTI]

At CTI we keep track of each failure and try to improve and prevent future failures. We see four major categories of failures.

1. Flying 10-year old 'garage sale' reloads without history - often outside of the package - and not checking the grains before assembling the motor.
2. Pro38 "oops, I forget the casing" failure. Believe it or not, this still happens. Excited fliers load the Pro38 reload without screwing it into a casing first.
3. Ignore the instructions failure. Many of our Pro75 or Pro98 motors require very specific steps to assemble the motor.
   • "I didn't think that would make a difference to bond the grains in, so I decided not to do it".
   • "I thought 5 min epoxy would work as well" - Although we clearly specify what adhesive to use.
   • Wrong location of a base grain.
4. All others (this is where we can do better and are improving all the time):
   • Ejection charge problems;
   • Liner burn-throughs;
   • Hardware problems;
   • Propellant issues (very rare).

 

[sodmeister]

OK ,this was not me...HONEST !!!! But I`ve seen the #2 PRO-38 "OOPS ,I forgot the casing" failure first hand that Jeroen mentioned.

No names will be used ,but it happened two years ago on a 3" PML Bullpuppy ,just the grains (3) and no case !

...3....2....1......FIRE ! The rocket burned down on the pad and was destroyed.

Always ,always reload your own cases and grains and do not trust others to do it for you !!

Otherwise ,I have not seen a CTI failure yet ,just a weak ejection charge ,but that`s easy enough to fix.


Paul T

 

[tightwad]

I have had more failures of Estes D-12-5's than any of their other BP motors and with no HS within two hours drive of my home, I switched over AT RMS. The 2 failures of RMS were my fault because I put the delay grains in backwards. Since then I had no RMS failures and I been doing BP since the early 60"s and At for at least 10 years. So, too answer your question on reliability, both systems are proven and reliable and it all breaks down to dollars and how much time and desire you want to invest in this hobby. Good luck and happy flying.

 

[CarVac]

I find that if you give a rationale for instructions (such as grain bonding), people are more likely to follow them.

For example: "Once out of the plane, inflate your life vest" versus "If you inflate your life vest in the plane, you may be trapped by rising water."

 

[chadrog]

Two notable failures - an Aerotech load in which I forgot the ejection charge, a CTI load in which they forgot the ejection charge. Neither result was pretty.

 

[MasonH]

Cti: 99.99%
At: 1 in 342 (according to Al Gloer)

 

[stickershock23]

one more thing to think about. CUSTOMER SERVICE... a failure is going to happen sooner or later. and when it does.... you gotta ask for a warranty.

if they dont cover it for you or give you hassles then you are loosing out. thats money out of your Budget for basically nothing.
If they do take care of you... well then that is the best out of a bad situation..

I have had a couple of CTI motors fail on me.. I was taken care of before I left the flying field. basically no questions asked. and when you are spending 50 to a couple hundred bucks for a reload plus the price of a case. THAT is worth its weight on gold.

I am about out of brand A cases due to failures and NOT being covered for them... no loss to me when they are gone they are gone, but CTI I will ALWAYS buy more know that they are standing behind their product 100% without a doubt... you cant buy that.. PERIOD!

 

[bill_s]

Well I've been taken care of well enough regarding warranty so far. I didn't even have to send them the spent motor. But I can see that regarding assembly-intensive Aerotech RMS, warranty could be an issue. Unless the company were to take the stance of the customer is always right, even though they know they aren't. It would be easier for CTI to take that approach, since assembly is simpler and distribution more exclusive. I think you make a worthy point, though -- not that "company A" is evil but they make a product that, when you really come down to it, manufacturer error is almost never possible to fully prove, there's too many variables outside their control.

But that also brings up why I started this thread -- warranty CAN'T always make up the loss. Even in cases it's a kit rocket that is destroyed and the manufacturer sends a new kit, it's not assembled and painted.

I'm still considering that I'll wait to get into reloads with a 3-grain cert special CTI ... now that's an awesome deal without equivalent in 40% off Hobby Lobby 29s and relatively cheap 24 mm SUs. But that'll have to wait until I build another rocket :evil:

 

[MarkII]

That you're trying to talk me into a second case already doesn't exactly convince me ... although it would help justify the drilling tool :dark: . Also my 24mm-only rockets will be flying high and drifting far when they get the occasional F.

I really don't know how far I'm going with this rocketry hobby any further than the next launch, but then if I have any more motor problems that could be it.

BTW, with RMS is it possible to reduce the ejection charge? The 24 mm charges are ridiculously overpowered enough for rear ejection, yet 29 mm is really the right power range.

Just offering you more options, that's all. There are a heckuva lot more motor options with 24mm reloadable motors than there are 24mm single use motors; the reloads range from D to F in impulse. And who says that you can only use 24mm motors in rockets with 24mm mounts? I use them all the time in my SLS and similarly-sized mid power rockets that have 29mm mounts. This is my Eos on an F35W (24/60) reload this past May:

[YOUTUBE]rp-LD8Il3-Q[/YOUTUBE]

 

[bill_s]

^^-- It is a good suggestion except both is too tempting .... I could fly 24 mm in all 3 of my rockets but all different delays vs. reloads sold in 3-packs -- do you use the drilling tool? I like the idea of it, getting the right motor sizes plus delays is a constant issue. Just another 20 bucks

 

[qquake2k]

^^-- It is a good suggestion except both is too tempting .... I could fly 24 mm in all 3 of my rockets but all different delays vs. reloads sold in 3-packs -- do you use the drilling tool? I like the idea of it, getting the right motor sizes plus delays is a constant issue. Just another 20 bucks

I have two 24/40 cases and two 29/40-120. I also have the drilling tool. It makes it really easy to dial in the delay you want. I order all of my reloads with the longest delay possible, and drill them for what I need.

 

[CarVac]

I always use a 1/4" center-cutting (the kind with the extra ground surface so it cuts right at the very tip) drill bit, and measuring the hole with calipers. The only time I ever had an incorrect delay was when I had to increase the length of a G76 and the vendor didn't have the correct HDK, so I was trying to drill out a slightly longer delay grain than I needed.

 

[MarkII]

^^-- It is a good suggestion except both is too tempting .... I could fly 24 mm in all 3 of my rockets but all different delays vs. reloads sold in 3-packs -- do you use the drilling tool? I like the idea of it, getting the right motor sizes plus delays is a constant issue. Just another 20 bucks

I have the AT drilling tool but I haven't had any need to use it yet. So far the delays that came with the RMS reloads that I have used have been right on the money for the rockets that I have flown with them. I don't expect that to always be the case with every rocket that I have, though, which is why I have the tool. I use the Pro38 DAT in my CTI reloads.

 

[rocketkid88]

I've flown a few hundred BP motors without a problem.

I've flown a handful of AT SU and reloads, I had a SU G80 CATO and blow the nozzle off (no damage to the rocket) and it was replaced by the on-site vendor. More recently I had an old E16W reload for the 29/40-120 burn verrry slowly. The grain was slightly swollen, but I just took a small file to it to clean up the center slot and ends to get fresh propellant showing, as I had read about on here. It was hard to light... when it lit, it took a while to build up pressure (sitting on the pad) then took off so slow it arced over at burnout and lawn darted, then ejected.

That can't be attributed to the manufacturer though. I have three more G64s of the same vintage, but I'm not going to risk loosing another rocket. All in all, the G80 has been my only real problem... its amazing how reliable mass produced hobby (and high power) motors are!

 

[rcktnut]

That can't be attributed to the manufacturer though. I have three more G64s of the same vintage, but I'm not going to risk loosing another rocket.

I used 4 G64's this summer dating back to 2000. All worked great. I sand the top 1" of the grain slightly, all lit the first try. I just looked have 3 more left from 2000 and a bunch from 2003. Most of my G64 supply are one grainers.

 

[bill_s]

I decided I'm not going with reloads yet. The consensus here is that they are somewhat more reliable, but I should expect better. I'll be being extra careful to do everything exactly right and if I still have above-average failures I'll probably change brands or at least start making my own motor type Avoid list.

The main reason is that I have to travel somewhat far to go launches, and even take off work if they're on Saturday, so my time there is expensive. I've only participated in 2 organized launches so far and I find prepping my rockets enough "fiddly" stuff to do in field conditions, and stay busy launching, retrieving, watching, socializing, and occasionally chilling out. Maybe after I get more comfortable and organized it won't seem like a problem.

Costwise, I calculate up to 30-40% savings for AT reloads vs. SU midpower, but if something happens to a motor case those savings can be erased. In 2 launches, I've seen 2 rockets eaten and I think someone lost a motor case. So the question is not actually that obvious to answer, on cost alone. Plus I will be needing a mix of 24 mm and 29 mm motors. Etc...