The Estes A8-3 engine weighs .60 oz.
The Quest A3-4 engine weighs a bit more at .63 oz.
Even without the paper label wrap, the fit was tight. On the left is the engine in the Dragon Ship 7 engine mount. The engine stops about 1/2" out where there is a slight compression swelling.
The fit was also too tight in a F-104 Starfighter. I didn't want to force it and risk crimping the engine mount tube.
The slip fit was fine in my payload altitude model.
Fit was also easy in my Saros clone. The engine slid in and stopped at the engine block. Both these rockets are friction fit (tape wrap retention) with no engine hooks.
Again, this single sample engine doesn't have a paper label wrap. A engine with a paper wrap probably wouldn't easily fit in any of the models I tried.
Some have peeled off the label, but mentioned a lot of sticky adhesive was left. Quest has said the next run of engines will have a slightly smaller outside diameter.
I’ve flown 19 of these now (with one misfire so far).
ReplyDeleteYou’ll find that the current ones, with the label on, fit in an ST-7 motor tube about the same as a label-less one fits BT-20. But there also must be some tolerance on “BT-20” as well as the speculation about glue shrinkage around centering rings. A label-on Q-Jet goes right into my just-finished Citation Patriot reissue. Not that I would dare fly it on even the Bs....the delays tend to run long, too (at least for now). Maybe when the Cs and Ds come out.....
I found that the placement of the heat shrink on the “initiator” is not always a perfect depth indicator - the picture in your other post is not that unreasonable.
Let’s just call them a work in progress at the moment.....
Hi Bernard,
DeleteI haven't launched the only Q-Jet is have, an A3-4. You're probably right, different models, different rates of engine tube shrinkage seem to effect the kit.
I'm an optimist, I think they'll be better with the next batch.
I guess I can’t edit what I just put up....on the Dragon Ship 7, try being very rigorous about aligning a flat side of the hex-shaped ejection charge container with the engine hook. Judging by where it stopped I think that’s why, rather than the slight OD increase at the nozzle.
ReplyDeleteHi Bernard,
DeleteAfter reading some forum posts, I was aware of the issues with the hex cap and engine hook fit. That could be a problem for many of my builds, I tend to cut off the finger tab and flip over the hook in the mount. I'll find out soon enough.