motor diameter differences

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Well-Known Member
Feb 24, 2009
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I've noticed something recently: Quest 18mm motors have a smaller diameter than Estes 18mm motors. I really have to wrap masking tape around Quest motors in friction-fit mmts, and not so much on the Estes ones. Anybody else notice this?
I've only noticed this difference on a few A6-4's. Since the motors are made by different manufactures, on different machines, I'd say its TSIOTMC syndrome..."The Slight Imperfections of the Master Craftsman". Motors seem to work as advertised.
Actually, I beleive that the motors are *specifically* manufactured a little narrow so that they can accept the stick on lable that they use (since they don't print right on the motor case as Estes does). They may have over compensated, but they didn't want a situation where you couldn't get the motor in because of the lable.

Not positive of this but beleive I've heard this before.

I often find Quest motors to be slightly narrower than Estes ones. If push came to shove, I'd prefer to have to wrap more masking tape around a loose motor, than have to try and peel off a layer from a tight motor.
I collect motors (they are a nice, dirt cheap rocketr item to collect), and Quest motors are a real collectors dream (or nightmare!)

There are some that are made 17.5 mm x 18mm. They are too slender and allow EJ pressure to excape. These are often the Blue A6-4s, but some Blue B6s I have are 17.5mm as well.

Th Quest 'Black n Blue' label C6s are 18mm in dimeter, but are too long, by about 3mm. These are made in Germany for Quest, and have German printing under the label.

The older Quest 'White/Orange' label motors are usually 'spot on', but are no longer manufactured. (Most of these were made on the old MPC motor making machine that FSI had)

I am looking to buy some of the 1991 'Green/White' label Quest motors if anyone has any.
Any opinions out there about the Quest motors in terms of reliability and performance?
They generally seem to be cheaper at my local hobby store, but I've resisted the urge to save a buck and abandon the old tried and true.
I've found nothing wrong with Quest motors reliability-wise (apart from the aforementioned narrowness, but thats easy to solve).

I prefer them, to brand 'E', performance wise; as they are louder & smokier. :cool:
I have found Q motors to be pretty much equal to E motors. Quest are often smokier... the exhaust is blacker, and there seems to be a bit more 'crud' left over after firing.
The motors are fine, performance-wise (and generally a buck cheaper)... but those tigertail ignitors leave a lot to be desired.

I kinda like those tigertails... of course, I do not use the plastic plug, but rather the true and true 'recovery wadding spitball' method of igniter retention.

What sort of problems have you experienced?
Two problems specifically (and these may fall under HAL 9000's "human error" category):

1. Tigertails seem to require absolutely fresh AAs in the launch controller.
2. Tigertails seem to have trouble igniting motors not labeled with "Quest".

By comparison, the Estes ignitors fire on less-than fresh batteries and will ignite the Quest motors.
Hmmm... I see why I have not had issues with these igniters then.

1) I Use a 'car jump starter' for my power source. It has 12v, and can supply 15 amps.

2) I have never tried them in 'Non brand Q' motors. I will have to give it a go.

Originally posted by graylensman
The motors are fine, performance-wise (and generally a buck cheaper)... but those tigertail ignitors leave a lot to be desired.

I'm with Ya greylenman! the motors are fine the A4-6 is a very nice motor, but those darn tigertails have got to go!! they are as reliabile as copperheads, just plain bad.
It's my understanding that quest is looking at changing their igniters very shortly. Hang in there They'll be better soon and from what I'm hearing as universal as solar igniters. FYI they will also fit Micro-Maxx nozzles YEA!
Yep - I've been using a lot of Quest A6-4 and B6-4s. Great motors, great price - especially in bulk.

My recent luck with the Tiger Tails has also been bad. At a recent launch - 3 out of 4 were failed. 25% failure rate would be bad enough in my mind, but 25% success is just plain horrible. I had a fully charged 14.4v battery, so the equipment wasn't at fault. The rest of that day's firings went fine - including a few that were done on plain strands taken from picture hanging wire (always keep a bunch of these "old tech" ignitors in my kit as as backup.)
I read somewhere that Quest motors use black powder for propellant and that is why they smoke more and also why they are less expensive than Estes motors, but they work just as well.