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  #1  
Old 11-18-2020, 08:02 AM
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Flash Flash is offline
Semi-Pro Rocketeer TRA 10484 L2
 
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Default Q-Jet motor max lift weights ?

The max lift weights of the C Q-jets seems very low to me? Less than 4oz?

Estes C5-3 is rated at 8oz

Estes C11-3 is rate at 6oz

Any thoughts?

C18-4 W
Motor Diameter: 0.698" (18mm)
Casing Length: 2.75" (70mm)
Total Impulse: 9.8 N-sec
Burn Time: 0.52 seconds
Average Thrust: 18 newtons
Delay Time: 4 seconds
Propellant Weight: 5.6 grams
Propellant Type: White Lightning
Motor Weight: 20.9 grams
Maximum Liftoff Weight: 113 grams

D16-4 BJ
Motor Diameter: 0.698" (18mm)
Casing Length: 2.75" (70mm)
Total Impulse: 12.4 N-sec
Burn Time: 0.79 seconds
Average Thrust: 16 newtons
Delay Time: 4 seconds
Propellant Weight: 9.9 grams
Motor Weight: 25.7 grams
Maximum Liftoff Weight: 128 grams
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  #2  
Old 11-18-2020, 08:17 AM
Scott_650 Scott_650 is offline
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Iíve always treated max liftoff weight as a guideline more than a rule - a small diameter, low drag rocket over the limit by a bit (on a calm day) will probably be fine, while a lighter but draggy rocket may not work well at all. Iíve used the initial version C/D QJets in heavier, low drag rockets and theyíve worked well, while my Estes 1/200 RTF Saturn V definitely doesnít like the D motors. What I havenít tried, other the the SV, is heavy draggy rockets over a C/D QJet.
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  #3  
Old 11-18-2020, 10:50 AM
TigerHawk TigerHawk is offline
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I've used the A3-4, A3-6, B4-4, B4-6, C12-4 and D16-4 Q-Jets and they've all been great launches and recoveries. I use the D16-4 in my Estes 1:200 RTF Saturn V and it works great. I've used the C12-4 and D16-4 in my MPC Red Giant and it launches it way up there. All in all great experience with them so far and looking forward to using the C18 and D20 Q-Jets.
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  #4  
Old 11-18-2020, 11:01 AM
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ghrocketman ghrocketman is offline
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I'm looking forward to the C18 and D20 as well.
Will try the short delay ones of each in my Mars Landers then get a bulk-pak of Ds.
Might even get out one of my old 1284 Space Shuttles to try the Ds too.
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Old 11-18-2020, 11:11 AM
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Quote:
Originally Posted by ghrocketman
Will try the short delay ones of each in my Mars Landers then get a bulk-pak of Ds.

They will be particularly good for heavier Outlander models.
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  #6  
Old 11-18-2020, 11:20 AM
Scott_650 Scott_650 is offline
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Quote:
Originally Posted by TigerHawk
I've used the A3-4, A3-6, B4-4, B4-6, C12-4 and D16-4 Q-Jets and they've all been great launches and recoveries. I use the D16-4 in my Estes 1:200 RTF Saturn V and it works great. I've used the C12-4 and D16-4 in my MPC Red Giant and it launches it way up there. All in all great experience with them so far and looking forward to using the C18 and D20 Q-Jets.

My Looney Tunes equivalent of the Red Giant and my MPC Enterprise both work great on QJets. Love using the D motors with an adapter in my Estes Vagabond, the faster takeoff is a fun change from the slower BP launches.
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  #7  
Old 11-18-2020, 12:42 PM
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5x7 5x7 is offline
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I think the weights on the Q-jet As and Bs should be heeded. I started out trying to fly models that flew well on Estes B6-4 but were too heavy for the Qjet B4-4.
There is a mistake in The Cs max weight recommendation since the C12-4 and C12-6 are both listed at 113 g. 200 would probably be a good number for C12-4. The C18 uses the same flawed recommendation for 4s and 6s. The C18 and D20s should probably also be higher since they have double the initial thrust.

Beyond that, the delays for the 4 sec are a full four or more. The C5-3 is the exception but the delays for Estes are usually shorter than listed.

As long as itís low enough to be safe.
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  #8  
Old 11-18-2020, 12:59 PM
Scott_650 Scott_650 is offline
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Quote:
Originally Posted by TigerHawk
...I use the D16-4 in my Estes 1:200 RTF Saturn V and it works great...

The QJet C motors work fine in my RTF SV but for some reason it just doesnít fly right on the D motor - I get a squirrely tail waggle that doesnít happen on a C motor. If I ever get one of my Dr. Zooch Saturns done the 1/200 Estes is being retired to display status anyway so itís not that big of a problem.
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  #9  
Old 11-18-2020, 01:09 PM
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5x7 5x7 is offline
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Quote:
Originally Posted by Scott_650
The QJet C motors work fine in my RTF SV but for some reason it just doesnít fly right on the D motor - I get a squirrely tail waggle that doesnít happen on a C motor. If I ever get one of my Dr. Zooch Saturns done the 1/200 Estes is being retired to display status anyway so itís not that big of a problem.

Check the nozzles on the D, I have had the nozzle surface and a bit of throat break out of a C and D. There was a pronounced jog in the flight path and both flights seemed lower than normal.

Last edited by 5x7 : 11-18-2020 at 02:10 PM.
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  #10  
Old 11-18-2020, 01:26 PM
TigerHawk TigerHawk is offline
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I actually have to use a engine adapter when I launch my 1:200 Estes Saturn V, with the Q-Jets, because I converted it to a 24mm with the FlightSketch conversion. Haven't even tried it with a 24mm motor yet, so I guess I should try it sometime.
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