This engine was from a bulk package, the bulk pack engines are unmarked black plastic casings and don't have a printed paper wrap. Personally I think these engines should have some sort of power designation marking. With no name, an A engine looks like a D engine. If you were to get them mixed up you could only tell them apart by weighing them. This engine diameter will be slightly smaller than an engine with a paper wrap.
This engine is from the first production run. All concerns about engine fit and the igniters are being addressed.
Here's the engine slipped into a standard BT-20 tube. The fit seems good but look close to see a slight pressure bulge where the nozzle is.
The picture on the right shows the engine slipped all the way in. It was a tight fit getting the bulge end in.
Here's the upper end.
Around the base of the ejection end cap is shiny, it looks like a bead of epoxy, just a guess on my part.
The old Enerjet engines had a ring of shiny epoxy around the graphite nozzle.
Set side by side, the "casing" of the Q-Jet is a little shorter, less than 1/16".
As I understand it, with the igniter fully inserted, the black shrink wrap should be even with the end of the engine. I tried a dozen times and this was as far as I could insert the igniter.
EDIT: the new Quest igniter instructions say the black shrink wrap piece will end up 1/8" to 1/4" above the nozzle.
The initial production run motors I received had some other issues besides the casing diameter.The hex ring front "hangs" up on the front bend of the engine hook of some models. Tabbed engine hooks seem to be the worst. This happens even if you rotate the engine to align the flat side with the bend of the hook. This is reportedly being addressed in following production runs by recessing the hex cap further into the casing. Also, the ejection charge is stronger than a regular BP motor. People are reporting damage from it. The initial run used .5 gram of powder for the charge, reportedly already reduced to .3 gram. And the instructions say to use tape to secure the ignitor to the motor during ignition. There are reports of the ignitor staying in the engine on the A motors during flight or clips remaining attached to ignitors that remain in the engine, holding the rocket down to the launch pad. The A engine apparently does not have sufficient thrust to consistently "blow out" the ignitor. Newer runs should have heat shrink tubing to retain the ignitor during ignition, similar to the red "straws" supplied with the old Quest BP motors. And don't substitute a balled up tissue paper plug for that. Composite propellant motors need a vent during ignition, something I learned from a TRF post. Anyway, the fixes should be seen in future runs of the motors.
ReplyDeleteHi BAR,
DeleteI've been reading the forum posts talking about the early flight reports. I don't want to criticize too much, I know the manufacturer will work out the bugs.
P.S. I found that a good way to label the black casings after the paper label and sticky glue have been removed is with a silver Sharpie. Using your tip, I write it on the nozzle end that protrudes from the motor tube. Laters.
ReplyDeleteHi BAR,
DeleteMy concern is if you didn't mark the engines, you have no way to tell them apart later on. Your suggestion of the silver Sharpie is a good idea. I always mark the engine designation on the paper retention piece on the Estes starters.
I can't get the igniter to go any more down like yours did, did it end up working with the black shrink wrap not all the way down?
ReplyDeleteHi Unknown,
DeleteThe new Quest Q-jet instructions say the black heat shrink will end up 1/8" to 1/4" above the nozzle.
Search for image 7: https://www.questaerospace.com/25-Pack_B4-6_Q-Jet_Model_Rocket_Motors/p4193205_18343746.aspx
I thought the black shrink wrap should be even with the nozzle face, but I guess not! The picture in the blog post (with the space between the black shrink wrap and nozzle) is correct!