Basically the diameter will be slightly reduced, the amount of BP in the ejection charge will be slightly reduced, and something will be done with the igniter to help retain it in the engine until ignition without resorting to tape.

__________________
Jeffrey Deem
NAR16741
CIA section 527

Narrowing the OD and recessing the hex cap front end.

also
reduce ejection bp from 0.5gram to 0.3 gram.
incorporate heat shrink tubing to hold igniter in, similar function to the red tube on the Q2G2 igniters.

__________________
Roy
nar12605

Sounds great!!!

I have always been in favour of 0.25g 3F NOT 4F.

With Quest's composite "C" and "D" Q-Jet motors coming out soon (and thank you, Roy--I'd forgotten about Brown vis-a-vis the 0.69" x 2.75" motor casings), I hope that Quest will also re-issue the 23.88" (60.6 cm) long Eagle (also labeled "Falcon," see: http://www.ninfinger.org/rockets/ca.../93quest10.html and http://www.ninfinger.org/rockets/nostalgia/94qst10.html ) and/or the 41.5" tall Super Eagle (see: http://www.discountrocketry.com/que...ter-p-2042.html , http://archive.rocketreviews.com/re...per_eagle.shtml , and http://www.google.com/search?source...1.0.DB_2u3L7Saw ), and:

Quest Aerospace (see: www.questaerospace.com ) has all of these rockets' parts available, but it would be great to have the kits, with their properly-colored parts and their decals! (Starter sets containing these kits, Q-Jet motors & igniters, and launch pads & controllers [the Eagle and/or Falcon were also offered in starter sets] would be attractive products.) All of these kits would be good matches for the "C" and "D" Q-Jets, and they could also use Q-Jet (or black powder) "B" motors. Their recommended motors are as follows:

Eagle/Falcon: B6-4, C6-5 (in the Quest catalog listings above)

Super Eagle: B4-2, B6-4, C6-5 (the EMRR review [see: http://archive.rocketreviews.com/re...per_eagle.shtml ] lists the B6-2, B6-4, C6-3, and C6-5, and the Discount Rocketry listing [see: http://www.discountrocketry.com/que...ter-p-2042.html ] says B4-2, B6-4, and C6-5)

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

I have been prepping models for our club launch tomorrow wherin I want to get more experience flying Q-Jet motors. To that end a couple of days ago I built an Alpha III with an ST-7 motor tube, and I focused tonight on prepping Semroc kits which also have ST-7 motor tubes. Along the way I tried Q-Jets, both with the label on and with it removed, in some other models.

On a whim I tried a Q-Jet in a just-finished Citation Patriot. And it went in, label and all, much to my surprise. That led me to trying some other models. In most cases of Estes models I had the problems I've reported further up in this thread. BUT - another suprise was a mid-1980's vintage Alpha (first version blow molded nose cone, red/black livery) and a Q-jet, label on, went in that model as well.

This got me to wondering - is it that doggone blue motor tube the culprit? You know, the one that came in with the green centering rings and the "Beta, Explorer, etc." series in the early 1990s and which has only recently gone away again? I grabbed the blue motor tube that was supplied in the Alpha III kit mentioned above and - NO way a Q-jet with the label on goes in that tube. One with a label off does with care.

Hmmmmmm......the models I'd been complaining about - another Alpha III and a Nova Payloader - both have the blue motor tubes. So now I'm beginning to think that the blue motor tubes, which are soft and apparently a touch undersize, are magnifying the fact that Q-Jets are a tiny bit larger in diameter than the typical Estes "18mm" motor.

The thing is - there is around 25 years' worth of Estes kits with that blue motor tube in them.

I also checked an earlier Alpha (early 1970's version) that is part original kit parts and part Semroc parts - this is another where the Q-Jet might go in with the label on...if I clean up the bottom end of the motor tube where I'd hardened it with CA a bit.

I did some quick checking of a couple of Estes motors as well as a couple of Q-Jets with my Harbor Freight digital calipers and still find the Q-Jets are .01-..02 larger in diameter (label on). I will have to check more individuals as well as Estes motors of various vintages (examples of recent ones are just a touch larger in diameter than 30-year-old ones, for example).



I sat down at a computer where ny wife's Facebook account was up and went to the NAR page and found a discussion of these motors that included Gary Rosenfield. It sounds like there, at least, he's been basically saying it's not the motors' fault they don't fit.....though they will be making them .005 smaller in the future. He also said the cases are supposed to be 0.698 +/- 0.003 inches in diameter. I have examples what are at least 0.01 larger than that - which is just enough to make 'em no go.


In any event, I have four models prepped with Q-Jets installed. Three have ST-7 motor tubes in them and one is the Estes ARF Solaris (which took a Q-Jet with the label on, albeit with a bit of care). The other three models all have a motor hook and I was able to get the ejection charge containers past the upper ends of the hooks with some care in alignment.

I'm also bringing more of the Q-Jets with me to the field, as well as that early 1980's Alpha that will take them. I'll come back to this thread tomorrow evening or Sunday and report further on flight test results.

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

Those are interesting findings. I never did like the soft blue Estes motor mount tubes (and especially, the "thick-walled stage coupler-like" BT-20-to-BT-50 centering rings for them, which had to be notched inside if the motor clip was to fit properly). This raises another question:

Do the Q-Jets fit properly in both the yellow and the gray Quest motor mount tubes (the latter, with factory-punched notches in order to fit in Quest plastic fin unit cans, come in their "Quick Kits")?

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

BEC, it would be interesting if you could take caliper measurements of a standard Estes motor and compare that with the measurements for the Q-Jets. Although it's obvious to me that they don't fit in motor tubes where Estes engines do.




Blackshire, I tried it in a Quest Seeker that I just picked up on EBay. It has the gray "Quick kit" tube. Fits nicely, label and all.

EDIT: Found a Quest kit I have that uses the yellow motor tube, the MLAS. The Q-Jet DOES NOT fit with the label on. Too tight. Can only get the first 1/4" of the front end in.


So looks like for the BT-20 (.710" ID) and the Quest yellow 18mm motor tube (.712" ID) you probably will have to peel off the label to get it in. For the ST-7 (.715" ID) and the gray Quest motor tube it may take the motor without peeling the label. Will hopefully be flying a few myself tomorrow, weather permitting.

Thank you--that's interesting, and it's good (for their own kits, too) that future Q-Jets will have slightly narrower casings.

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

grabbed a bunch of loose motors out of my ready box. Mix of A8, B6, and C6 motors, mix of mfg dates from late 80's to early 2000's. Measured front, propellant location, and nozzle.. Range is over entire range of motors; individual motors were usually +- .001 or .002



Front: 0.685 +- 0.003

Propellant: half were 0.690+- 0.002, half were 0.698+- 0.003

Nozzle: 0.702 +- 0.005

__________________
Roy
nar12605