Quest Long burn C6-5 Scorching??

[luke strawwalker]

Anybody seen this in any of your Quest long burn Chinese C6 motors??

We had our Challenger 498 club launch yesterday, and one of our guys, Mikus, tried one of the new long burn Quest C6's in his Estes Chrome Dome. The flight was beautiful, and those motors DO burn a LONG time... nearly all the way to apogee so it seems like. Anyway, the rocket floated down to within about 30 feet of the pads, and upon recovering it, we opened the twist-on Estes engine retaining ring that the Chrome Dome, Metalizer, and others use, only to find that the plastic locking ring was basically MELTED around the motor end! The upper end inside the rocket was fine, but the lower ring showed signs of the plastic basically liquifying and then resolidifying, because the metallic plating had basically 'floated off' and the locking tabs were nearly melted.

The engine casing itself was QUITE scorched-- the outer white paper label was pretty badly scorched in several areas, actually browning the paper from underneath! When we first opened the motor retainer, the casing was still too hot to hold. We gave it about half a minute to cool in the wind, and then I gently rocked the motor casing back and forth the 'break loose' the plastic retainer from the motor casing to prevent destroying it, and safely removed the still hot case. I then took my pocketknife and carefully split the case from front to rear along one side, and split it open. The inside of the casing was badly charred, of course, but there was DEEP charring BETWEEN LAYERS of the paper case, and in cutting it open I found it cut MUCH easier than trying to split an Estes casing, almost as if it were rolled together 'dry' with little or almost no adhesive between layers. The layers even split apart easily as I folded the casing open. The adhesive should have been quite soft from the engine heat, but there was no stickiness, and the paper layers split apart and looked quite 'dry'. The charring between layers was disconcerting, as it came pretty close to burning completely through the case.

Some of the guys were interested in the nozzle material, since it looks almost ceramic. I cut into it a bit with my knife, and scraped it, and it appears to be an extremely finely ground clay, almost like the clay flowerpots are made of, and it liberates a very fine almost chalk dust like clay particles when scraped.

I was just wondering if this is 'par for the course' with these motors, or are we seeing a 'hot load' or maybe some casings that were 'wound dry' or something that would explain the anamalous behavior...

In the meantime, ya might want to be careful what you put these in! Pics to follow! OL JR

 

[dlb]

it's not anamalous behavior, it's a long burn motor.
with 2.5 sec burn time theres lots of time to pass the temps thru the wall(CASE), as compared to a 1 sec burn time.

My suggestion would be to NOT use these on Plastic rockets.

I've had no problems with paper rockets, but notice how hot they are apon removal

 

[luke strawwalker]

SO this is typical?? There's a difference between a HOT case and a case scorched and almost burned through, though, granted, it didn't fail...

What would it do on a minimum diameter bird though, or in a CLUSTER!!!

One thing we noticed is that the casings seem quite a bit 'thinner' than equivalent Estes cases...

The most surprising thing to me, though, was how easy it delaminated and how 'dry' it was between layers...

Thanks! OL JR

 

[cls]

my Metallizer and Chrome Domes always get wrinkled near the motor mount, after a half dozen flights or so, regardless of motors used. Don't worry about it, those are beauty marks.

 

[spacecadet]

That does look more like a cheap firework rocket than a model rocket motor, though.
I have noticed melting on those locking rings even with standard C6's- theyr'e probably only good for a few flights. You'll have to revert to the 'masking tape and tight fit' method for that rocket.

 

[Peartree]

That does look more like a cheap firework rocket than a model rocket motor, though.
I have noticed melting on those locking rings even with standard C6's- theyr'e probably only good for a few flights. You'll have to revert to the 'masking tape and tight fit' method for that rocket.

I don't know about that. We've flown the daylights out of our Estes Amazon on everything from A's to C's and the plastic motor retainer is still pretty solid.

 

[adrian]

Another thing to note about those long burn "C6" motors is that if they're longer burn, either they're not C6's (lower thrust) or they're not C6's (higher total impulse).

The NAR data sheet for these motors confirms this. Whereas Estes and older Quest motors are shown to have an actual average thrust of 4.74N, the Chinese ones are rated at an average thrust of 3.45N. Don't trust them in the heavier rockets in which you might previously have tried a C6...

 

[shreadvector]

This is another duplicate thread on two different forums. i already answered this on YORF (and since this has nothing to do with "olde" rockets, I have no idea why it was posted over there).

Bottom line: I think the rocket was defective as we have seen this with Estes B6-2 motors.

https://forums.rocketshoppe.com/showthread.php?p=64795#post64795

 

[powderburner]

FWIW, I checked my notes for my last three Chrome Domes and I had 17, 15, and 9 launches on them before I finished with them. I do not have any specific notes about MMT damage but I do remember minor scorching (smoke discoloration?) throughout the aft end, and minor melting in a few places. I used A and B motors (Estes) on about 90% of those flights and only used a few C motors (also Estes).

 

[luke strawwalker]

Another thing to note about those long burn "C6" motors is that if they're longer burn, either they're not C6's (lower thrust) or they're not C6's (higher total impulse).

The NAR data sheet for these motors confirms this. Whereas Estes and older Quest motors are shown to have an actual average thrust of 4.74N, the Chinese ones are rated at an average thrust of 3.45N. Don't trust them in the heavier rockets in which you might previously have tried a C6...

Yes, we discussed this at our club launch awhile back, and online in one thread or another. With "X" total impulse and "Y" duration, the 'average thrust' can only be "Z" at a maximum. (Since average thrust times duration should result in the total impulse, neglecting peak thrust spikes and tailoff) I sorta found a workaround in this though, in that if you have a high but short thrust peak followed by lower than 'average' sustaining thrust for the remainder of the burn, and if you figured it more as a 'mean' thrust, then theoretically you COULD get the 'average thrust' rating higher... Anyway, yes you're correct, in that these motors, for that duration, should probably be classified more like a C4 instead of a C6.

At any rate, the scorching of the outer wrapper was of the most concern to us when it was recovered. That level of scorching evident in the photos seems to me to show the motor must have been nearing the ignition temperature of the outer casing wrapper. Meaning a little hotter and the outer wrapper would likely have burst into flames! Not a good day for your rocket!

I'm aware of the shortcomings of the Estes plastic construction methods, and I wasn't meaning to comment on that here, other than to note that there was sufficient heat transfer to basically liquify a plastic part, and that heat was from the INSIDE, not the outside as a result of hot exhaust plume impingement or base recirculation effects.

Thanks for your input guys... Just thought I'd offer a heads up! OL JR

 

[shreadvector]

I'm a big advocate of safety, but I am also an advocate of being careful about making claims that can negatively affect a product or company without many data points AND after numerous attempts to directly contact that company to inform them of the alleged problem and to allow them to answer/resolve the question/issue.

As for "bursting into flame", this sounds like 'incendiary wording'. Cardboard tubes will scorch when exposed to heat. My Estes body tubes (BT-50 with a BT-20 motor mount) get scorched from the delay afterburn. Have you witnessed the delay afterburn of a regular Estes motor? It looks like a highway flare and it would possibly alarm and frighten you. A motor tube will almost never be able to burst into flame because it just does not burn like that. Do a burn test over a bunsen burner (you can pull out FAR 25.853b if you wish) and tell us how the cardboard tube burns and if it can sustain a flame or if it self extinguishes.

As has been said by others, sometimes a casing is not perfect and there can be a burn through. This is rare these days on Estes motors and that is not an accident. From what I heard, they were very careful in choosing casing manufacturers who could meet their specs and those specs were developed to eliminate the rare but still occasionally reported burn throughs on C6 motors and D12 motors. The longer the burn, the more internal casing erosion down at the end just above the nozzle.

I would expect some erosion on a long burning Chinese Quest C6 motor and the real test of final casing thickness would be on a Chinese C6-0 BECAUSE a motor with a delay will expose the inside of the casing to several extra seconds of high heat/flame from the delay burning, but there will not be a lot of pressure that could lead to a burst casing. A booster will not have the delay or ejection charge, so you will be able to see the true amount of erosion from the motor propellant burn and the final wall thickness.

D5-P should also be useful for this.

Anyway, please work directly with the manufacturer to get your questions resolved.

And a final variable to throw into the data gathering: could the Estes models have been made with a softer plastic with a lower melting point? I have seen 'test' parts made with the production molds but with softer plastic. i have also seen some variation over the years with the cementability of some of the plastic parts in the same kits, and I can only assume there was a change in plastic. Maybe the newer "safe to eat" plastics melt too easy?

So, how about putting one of the Chinese motors into a Wizard and seeing how it does? One unpainted Wizard to see how the brown BT-20 does and one painted Wizard to see how the paint does (bubble or not?). Of course, airflow over the fast moving Wizard will be different and possibly cool it off better than the fat slow moving plastic Estes BT-56 model where the heat is retained in the plastic mount.

 

[MKP]

I just dissected a Quest C6-5 in similar way that you have, and I really didn't see anything that concerned me too much. The casing is indeed thinner than Estes casings, but I did not see any of the scorching that you mention. Just some browning at the forward end due to the ejection charge like Shreadvector mentioned. The layers did pull apart fairly easily, like you said.

Perhaps the plastic fin can allowed more of the ejection gases to blow by into the engine chamber.

 

[shreadvector]

I remain open to multiple possibilities listed in my post above as well as the famous "was the rocket suspended the distance above the blast deflector as specified in the kit instructions?"

If the BT-56 blastic-butt Estes models sit on the deflector, the "blast" will 'infringe on their personal freedoms' like a flock of soiled budgies.

 

[RoyAtl]

I remain open to multiple possibilities listed in my post above as well as the famous "was the rocket suspended the distance above the blast deflector as specified in the kit instructions?"

If the BT-56 blastic-butt Estes models sit on the deflector, the "blast" will 'infringe on their personal freedoms' like a flock of soiled budgies.

Darn, and I bet you can't find a recording of Terry Jones saying that in the character of a Scotland Yard Inspector.

 

[Mikus]

I remain open to multiple possibilities listed in my post above as well as the famous "was the rocket suspended the distance above the blast deflector as specified in the kit instructions?"

If the BT-56 blastic-butt Estes models sit on the deflector, the "blast" will 'infringe on their personal freedoms' like a flock of soiled budgies.

You tell me, here's a picture. Chrome Dome on the right.

The melting occurred on the INSIDE of the ring, not the outside.

 

[luke strawwalker]

You tell me, here's a picture. Chrome Dome on the right.

The melting occurred on the INSIDE of the ring, not the outside.

I think I've said that twice already, Mikus, but some folks don't seem to get it...

Some folks don't seem able to look at the freaking pictures either... Maybe you'll have better luck! Later! OL JR

 

[Mikus]

I think I've said that twice already, Mikus, but some folks don't seem to get it...

Some folks don't seem able to look at the freaking pictures either... Maybe you'll have better luck! Later! OL JR

Nah I'm not going to worry much about it. Honestly, I wasn't really caring until that "sit on the deflector" crap started.

I mean I may not have Shred's many years of vast experience under my belt, but I think I can figure out NOT to set the rocket on the deflector plate. Sheesh!

 

[luke strawwalker]

Well, I've been convicted of 'badmouthing a manufacturer without a thousand and one data points' for just pointing out an anomalous result of a flight of some pretty new motors at a club launch in a brand new rocket on it's first flight of known design and parameters, recovered pretty quickly and observed by at least a half dozen well experienced rocketeers, to seek information and experiences from others and give a possible 'heads up' to folks about gaining a bit more experience with these motors and to keep their eyes open, but hey, I guess I'm just a muckraking manufacturer badmouther so I'll just quietly return to my dungeon and bask in the munificence of those infinitely superior to me who don't seem able to look at a photo, read a dispassionate description of what happened, and draw a plausible conclusion...

Or not....

OL JR

Just for the record, I like Quest and I like their motors, and I REALLY like their ignitors and I'm NOT badmouthing anyone! I would just hate to think of someone popping a motor into a prize antique, rare, or scale kit and getting a VERY sad or surprising outcome. Yes it's ALWAYS a chance anytime you push that launch button, but information IS power and more information is ALWAYS a good thing... IMHO...

 

[rokitflite]

You pushed the launch button too hard... That was the cause.

 

[luke strawwalker]

Well, coulda been worse, Mikus...

Least it didn't hang on the launch rod... LOL (ducks and runs)

"Now on pad 3, Mikus's Der Red Max... Doing a static test on a C6-5... "

Later! OL JR

 

[Rocketcrab]

I help a fellow club member with a 4-H Rocketry Program, and we have used Quest kits and motors every time. We've used the Big Betty kits every year, and this year we also had 4 kids return from last year, so we built Terrier-Orions with them. Quest has always been great in helping us out with the program.

Yesterday at a club launch, we flew some of the new Chinese made C6-5s in a Big Betty, just to see the difference between them and the Estes C6-5. They flew as advertised, giving ol' BB a nice ride every time. But what does concern us is the issue of the high temperature of those motor casings after they are used. They are very hot, to go along with the scorching and burn-through.

Since we have not reached the point in the program where the kids are launching their models [still building], we'll have to remember to instruct the kids not to touch the expended motors when they retrieve their models, and to let them cool down. We may also have to reconsider what products weuse in the program next year. It's one thing for an old phart like me to fly them [no problem], but I don't want to be responsible for a 9-year old 4-H'er running around screaming that his/her hand hurts.

 

[luke strawwalker]

I help a fellow club member with a 4-H Rocketry Program, and we have used Quest kits and motors every time. We've used the Big Betty kits every year, and this year we also had 4 kids return from last year, so we built Terrier-Orions with them. Quest has always been great in helping us out with the program.

Yesterday at a club launch, we flew some of the new Chinese made C6-5s in a Big Betty, just to see the difference between them and the Estes C6-5. They flew as advertised, giving ol' BB a nice ride every time. But what does concern us is the issue of the high temperature of those motor casings after they are used. They are very hot, to go along with the scorching and burn-through.

Since we have not reached the point in the program where the kids are launching their models [still building], we'll have to remember to instruct the kids not to touch the expended motors when they retrieve their models, and to let them cool down. We may also have to reconsider what products weuse in the program next year. It's one thing for an old phart like me to fly them [no problem], but I don't want to be responsible for a 9-year old 4-H'er running around screaming that his/her hand hurts.

Good to know we're not nuts down here Crab...

Let me ask, have you seen this level of 'wrapper scorching' after removing the motors from the models?? Just wondering if our incident was a 'one off' or if this is fairly common...

Thanks, and I agree about the kids... gotta watch over their shoulders to keep em safe... OL JR