Just tried the q-jet composite motors by aerotech

[Long_Gone]

They are expensive to loose. Maybe if there were enough interest we could appeal to Aerotech and see if they could make them. Like buy in advance or something.

 

[shockie]

Terry,

What possible model do you have in mind for an A3-6? I have a few of these and I'm not sure they'd even be OK in a Viking or a Wizard or other similar MD model....

That said, after the initial teething issues (and that case diameter problem) they are very nice motors across the line.

Sterling silver upper stage as a single stage

 

[shockie]

Literally, no. But figuratively as it was stated, yes. He meant they’re fast. Or at least that’s how I took it.

a lot of 18mm Estes rockets were never designed for composite propellant. But that doesn’t mean I’m not gunna have fun sticking the motors in there and seeing what happens!

EXACTLY

 

[shockie]

Take note that the D10s at Sirius are plugged motors, no ejection charge.

I've got a few D10s and D21s that I may not be using anytime soon, but the only way I'd be able to sell them would be face to face.

Dual deploy 18mm? Flightsketch?

 

[BEC]

Sterling silver upper stage as a single stage

Maybe.....just remember that Aerotech delays tend to be closer to the full duration than most Estes delays. Having done some recent FlightSketch firmware testing using just the sustainer of my Sterling Silver I'd guess it'll be a little a late but not too bad. Here's an A8-5 flight: https://flightsketch.com/flights/2035/

 

[shockie]

Maybe.....just remember that Aerotech delays tend to be closer to the full duration than most Estes delays. Having done some recent FlightSketch firmware testing using just the sustainer of my Sterling Silver I'd guess it'll be a little a late but not too bad. Here's an A8-5 flight: https://flightsketch.com/flights/2035/

I really need to model this in Openrocket and see what it gives me .......

 

[Arsenal78]

I flew one of the new C18 Qjet White Lightnings and I'm a bit disappointed in them. Very fast burning motor, might as well be a blue thunder with a visible flame. I can't quite figure out why Aerotech is making an E26 Qjet when we already have an E20W. They need to make an E around the area of an Estes E9/E12.

 

[prfesser]

Without revealing any formula information---and I've never seen a Qjet so I may be full of old bootlaces---but if the nozzles on Qjets are the same stuff as are in Estes motors, they should erode to a larger diameter. That has to be taken into account when designing the motor, and it's not necessarily a trivial exercise. Especially with motors that have a very tiny nozzle throat.

 

[neil_w]

I flew one of the new C18 Qjet White Lightnings and I'm a bit disappointed in them. Very fast burning motor, might as well be a blue thunder with a visible flame. I can't quite figure out why Aerotech is making an E26 Qjet when we already have an E20W. They need to make an E around the area of an Estes E9/E12.

I would tend to accept prfesser's explanation that it's a practical matter.

However, I appreciate that they're less total impulse and cheaper than an E20. I don't always want the altitude that an E20 is going to give me on my larger LPR rockets.

Quite possibly I'll get even more use out of the D22s.... but first they need to come on the market and I need to try them out.

 

[Long_Gone]

I really like the q-jets so far they have performed very well but i am flying a 2.7oz rocket almost anything does a good job, except A's at least Estes A8's they flew very low. I will try the Qjet A's and see if they fly good. I must say the igniter's are better than Estes and the motors ignite first time every time so far.
My .02

 

[AeroTech]

As Prfesser says, when you design an 18mm motor with composite propellant there are limitations. In the case of the Q-Jets, one of the key limitations was the size of the nozzle throat. It cannot be too small to fit an initiator (igniter). So that drives the burn rate to produce sufficient pressure with the minimum throat diameter and that drives the burn time. Also, black powder burns at a much faster rate than composites at low pressure. So you need more surface area with composites to generate sufficient mass flow.

 

[neil_w]

As Prfesser says, when you design an 18mm motor with composite propellant there are limitations. In the case of the Q-Jets, one of the key limitations was the size of the nozzle throat. It cannot be too small to fit an initiator (igniter). So that drives the burn rate to produce sufficient pressure with the minimum throat diameter and that drives the burn time. Also, black powder burns at a much faster rate than composites at low pressure. So you need more surface area with composites to generate sufficient mass flow.

Is that also true for the 24mm Qjets, which are also fast burners?

 

[Ez2cDave]

Also, black powder burns at a much faster rate than composites at low pressure. So you need more surface area with composites to generate sufficient mass flow.

Faster than "Warp 9" propellant ?

Dave F.

 

[AeroTech]

Faster than "Warp 9" propellant ?

Dave F.

At black powder motor pressures, yes.

 

[AeroTech]

Is that also true for the 24mm Qjets, which are also fast burners?

There are more design options with 24mm.

 

[Ez2cDave]

Faster than "Warp 9" propellant ?

Dave F.

At black powder motor pressures, yes.

Does that hold true, both in end-burner and core-burner motors ?

Dave F.

 

[Bruce]

Couldn't the ignitors for 18mm motors be made longer and skinnier so that the nozzle throat could be made smaller?

 

[Ez2cDave]

Couldn't the ignitors for 18mm motors be made longer and skinnier so that the nozzle throat could be made smaller?

The nozzle throat must be properly sized, in order to control the chamber pressure inside the motor.

However, a different, slim, igniter design would be most welcome !

Dave F.

 

[ep29030]

Agree! To much farting around loading them up ....

Farting at launches = good reason to keep social distancing in place after COVID is over

 

[AeroTech]

Does that hold true, both in end-burner and core-burner motors ?

Dave F.

Changing the grain geometry changes the surface area and mass flow rate, but not the intrinsic burning rate.

 

[Rocketjunkie]

Mine are about 18" long and fit a B4 QJet. Made with 30 gauge wire wrap and tungsten bridge wire. Commercial dip.

 

[Ez2cDave]

Mine are about 18" long and fit a B4 QJet. Made with 30 gauge wire wrap and tungsten bridge wire. Commercial dip.

Do you have any more pics of the igniter-making process ?

Dave F.