Got that right! I don't think I'll fool with A's and B's. I'll get a sampling of C's and D's.

__________________
I love sanding.

I'm of the same opinion. C's and D's, but not A's and B's at these prices.
$4/each for A motors ???
C'mon noww...

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !

Well, my order of Q-jets from buyrocketmotors.com arrived today (while I was out supporting a launch for a group of homeschoolers).

First impressions: nice package. Nice that there are a few big squares of Quest-style (float parade tissue) wadding in the package. BUT - they don’t go in my models - at least most of them. They are too large in diameter.

If I peel off the label, then clean the label residue off the case with Goo Gone then I can get them in more models but even then they are snug. So the first few models I wanted to try them in - models that I’ve flown many times and with an altimeter aboard - in particular a certain Alpha III (25 flights) and a circa 2008 bulk-kit Alpha (63 flights) - I won’t be able to try them in at all. Depending on how much the upper end of the motor hook projects, one may or may not get the hex-shaped ejection charge container past the hook, even with the label off the motor.

Models with ST-7 motor tubes (I grabbed my current flyer Semroc Mini Aero Dart) fare better, but even there they are snug with the labels on. And once you try to put one in a model it doesn’t want to go in, the label starts to peel at the top and it just gets worse. It’s like friction-fitting a motor with cheap masking tape that starts to peel and wrinkle if you get it even slightly too tight and really makes it worse (something I got some more experience with today, since the homeschool group built Vikings).

They were apparently delayed because the first batch of labels was “too thick”. Even without labels they are about 0.015 larger in diameter than recent production Estes 18mm motors. It’s just enough to be frustrating.

Here’s hoping they turn out to be worth the fuss in use. I will try to put a couple in the air tomorrow - maybe in that Mini Aero Dart. I’d toss together another Alpha III and make a few subtle modifications - but my wife and I are off to our grandson’s orchestra performance now and I’m likely not going to be able to do so tonight.

So much for drop in replacements in the Estes education market.....

*sigh*

__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE

I provided detailed feedback directly to Gary. He said future batches will be .005 smaller diameter .

I also had very strong ejection charges in the A3-4 motors flown. He says they will look at reducing the amount of ejection charge. Good idea since they will be used in small models.

Also, don't use too much tape for the initiator or it will stay attached. A clever fix is already developed which will eliminate tape.

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-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

I'd be tempted to chuck it on the lathe and knock a few thousandths off.

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I love sanding.

Good!

I took my Harbor Freight digital calipers to the four motors I've liberated from the packages - A3-4 and B4-6, now one with a label, one without in each. With a label they are running around 0.712 inch OD at the widest point (they are NOT smoothly cylindrical like, say, an Aerotech D-10). Since the nominal ID of BT-20 is 0.710 inch, that's obviously an issue. ST-7 is 0.715 inch ID, which explains why it does work there, albeit snugly. With the labels off I get ODs of 0.707 - 0.708 which does work in a clean BT-20 motor tube or a plastic fin can with a threaded retainer (say, Solaris).

I will put the now label-less A3-4 in the Viking I put together yesterday before the homeschool launch today. It's modified with a small payload section and I flew it today on its one flight with a MicroPeak aboard (on an Estes A8-5 with a 1997 date code) and have that one data point. I will have a short opportunity to fly on a big field tomorrow and I wanted to try some of these out. I think I'll open up a B4-4 pack and put one of those in the aforementioned Semroc Mini Aero Dart. I have a recent data point (FireFly) with that model as it flew on a Chinese Quest B6-4 on Monday at the same field when I was out flying with my son and grandson.

On the tape....how about the old fashioned little ball of wadding instead?

Added: I just took a B4-4 out and put the calipers on it before even attempting to put it in a model (and therefore damaging the label). It's 0.716 inch at its widest at the ejection charge end and 0.714 inch at its widest at the nozzle end....and the two spots are not one above the other on the motor.

If Gary can get them down by .005 inch AND make them smoothly cylindrical that will solve this. Not knowing how their tooling works I hope this doesn't mean all new tools. If it does, they should go for .01 inch off and get them down to the same diameter as an Estes motor....

Just to be clear - I really want the Q-Jets to succeed. I think that's why, at the moment, I'm so disappointed I can't just pop them into models I've been flying a good deal lately and check out how they work.

__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE

All these issues could have ( and should have ) been caught in pre-production. How hard is it to take a prototype with label and check for fit in a BT-20 tube? And didn't they flight test these engines with the ignitor tape retention method? As mentioned, time to go high tech and use the old tiny ball of wadding crammed into the nozzle trick. Reminds me of kit manufacturers who don't flight test their models before bringing them to market. Tsk, tsk.
On the plus side, I did manage to get a QJet to fit, albeit snugly, with full label inside an Estes E2X model. I believe the Chinese made kits have a slightly larger diameter motor tube. So all the schoolkids flying their RTF and E2X rockets should be OK.

Maybe schools for rich folks. They aren't cost effective for school launches. A bulk pack of QJet A3-4's cost about $30 more than Estes A8-3 bulk packs.

__________________
I love sanding.

Unless the "street" price of those motors comes WAYYYYYY down, those A and B motors will soon be history.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !

This is precisely why I am no longer an Aerotech (ET) dealer. I kept ordering (prepaying) for 24mm motors that didn't fit in 24mm kits even the ones I make with a slightly bigger ID. No thanks. Such a silly production error.

Jerry