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#131
05-28-2019, 03:30 PM
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I would call the conditions for each flight "light and variable" or a little more. In looking at my uploaded FlightSketch data, it is showing winds as follows: Flight 1 - May 5th - Estes C6-3 - winds of 7 mph gusting to 10. As I recall this flight arced some into the breeze but nowhere nearly what I was expecting after prior posts on TRF about this model. Flight 2 - May 11th - Q-Jet C12-4 - winds 3 mph gusting to 5. This flight was just about arrow straight on the way up. Deployment timing was just about perfect. Flight 3 - May 12th - Q-Jet D16-4 - winds 2 mph gusting to 6. This was also a nice straight flight. Deployment was just a touch early. Weather data is from Dark Sky based on my location - I did not have a weather station set up.
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Bernard Cawley NAR 89040 L1 - Life Member SAM 0061 AMA 42160 KG7AIE 
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#132
05-28-2019, 03:46 PM
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Well, all-in-all, those flights sound fairly nominal. In other words, I detect no indication of 'unstable' flights in what you have described. Yet others are apparently reporting some degree of unstableness in their flights. Reason I asked about winds in your flights, since I was wondering if that might be cause of some of these negative reports. I was also wondering about motor selections, thinking that (maybe) motors such as the Q-Jets might be a bit heavier and therefore maybe shifting the Cg rearward. But your Q-Jet flights are sound, so that does not seem to be an issue, at least in realitively calm condiitons. BTW, do the Q-Jets, especially the D, weigh any consinderable amount more than a standard C6-3? Also, in summary, what are they reporting flightwise on this rocket on TRF? I don't read over there, so I don't know what they are saying. Thanks for your detailed flight reports! Earl
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Earl L. Cagle, Jr. NAR# 29523 TRA# 962 SAM# 73 Owner/Producer Point 39 Productions Rocket-Brained Since 1970 Last edited by Earl : 05-28-2019 at 05:19 PM.
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#133
05-28-2019, 04:59 PM
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As John said this morning - there is no way these models are unstable. What people are calling "unstable" has to be due to winds, dirty launch rods (so slower than normal boosting) and/or not getting the motor in all the way so that the fins are loose (and the thrust line is canted a bit).
Quick grab of random sample motors: Estes C6-3 0.80 ounce (the one that was in the images yesterday) Q-Jet C12-4 0.80 ounce Q-Jet D16-8 0.89 ounce (this should be the heaviest Q-Jet) Nope - it's not weight aft. There is lots of moping (from some of the same people) on TRF about severely arcing flights, mostly. I haven't seen any claims of instability over there....but there have been several threads besides the one similar to this one that John started there.
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Bernard Cawley NAR 89040 L1 - Life Member SAM 0061 AMA 42160 KG7AIE
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#134
05-28-2019, 05:27 PM
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Thanks Bernard for your as usual thorough and detailed response. It is good to know then that there may not be an inherent stability problem with the model. And it is very good to see the Q-Jets are basically the same weight as a standard C6-3, especially for the D motors. Possibly the issues people are seeing then are attributable to the causes you mention. To be honest, 200 feet on this model with a C6-3 actually seems respectable really. By the same token, if flown in any kind of real wind, I would actually expect an ‘arcing’ profile and reduced altitude. It ain’t gonna be an altitude champ with that motor anyway, but that is ok. I look at this as more of a demo rocket, not anything for raw performance. Thanks again for your experiences. Earl
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Earl L. Cagle, Jr. NAR# 29523 TRA# 962 SAM# 73 Owner/Producer Point 39 Productions Rocket-Brained Since 1970
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#135
05-28-2019, 09:08 PM
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I don't know where you guys are flying, but here in TN, we've had "light and variable" for the last week or two. Every chopper pilot that we've set up LZ's for has told us once it gets up to 75-100 ft, there's a good 25 knot wind and even better a few hundred feet higher. Sunday it was blowing east. Our pilot Sunday estimated they would get to NashVegas in about 38 minutes (about 115 miles)!
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I love sanding. 
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#136
05-28-2019, 10:58 PM
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In my case all three flights were at Sixty Acres park in Redmond, Washington. The wind does get "interesting" higher, but not quite like that!
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Bernard Cawley NAR 89040 L1 - Life Member SAM 0061 AMA 42160 KG7AIE
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#137
05-29-2019, 05:51 AM
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On my rocket, with a QJet installed, the retainer doesn’t tighten down enough to hold the fin unit securely. With an Estes motor it does. Since I have a sample size of exactly one that’s the data I have to use. If I’d noticed the fin unit wobble with the QJet I’d never have flown it, I didn’t but luckily it didn’t crash. My first flight wasn’t unstable or unsafe just not what I’d expected - the degree of arcing was higher than I’d call ideal. The winds that day were very light, 5mph with 8mph gusts. Now that I’ve flown it I know what to expect and can deal with it - not really a problem for me, I have hundreds of flights on Estes BP motors. What surprises me is that flight profile on a rocket that a great many first timers or folks who’ve been out of rockets for a long time are probably going to fly this summer. Hopefully I’m wrong and we don’t hear about crashes or erratic flights in July from less experienced people - I’ll fly mine again, maybe very soon depending on weather, on a C6-3 and a QJet and see what results I get.
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#139
05-29-2019, 10:56 AM
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Could be as simple as wrapping some masking tape around the top and bottom of the Q-Jet since the new versions are looser than an Estes C6 motor.
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-Fred Shecter NAR 20117 (L2) Southern California Rocket Association, NAR Section 430
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#140
05-29-2019, 11:21 AM
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*sigh*
First and third pictures shows motor NOT properly engaged with the ring at the top of the motor mount even though it feels as if it's stopped against something. Second and fourth pictures show it when it IS properly engaged. This is not a Q-Jet thing. The same is possible with Estes motors. It does take a little bit of force to get EITHER motor type properly pushed into that forward ring (see fifth image). And since a Q-Jet's case isn't as soft as an Estes motor's case you have to do this with intent. I found when trying to take these pictures that just tightening the retainer will push an Estes motor in all the way as the paper case will "give" a little. It doesn't feel like this would necessarily work with the harder Q-Jet.
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Bernard Cawley NAR 89040 L1 - Life Member SAM 0061 AMA 42160 KG7AIE Last edited by BEC : 05-29-2019 at 12:13 PM. Reason: added image of upper motor mount ring
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