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Author Topic: Bristol 72 Racer 30" span (1/10 scale)  (Read 2984 times)
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Bill G
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« Reply #50 on: October 02, 2017, 01:12:17 AM »

Thanks.  Started the TU 104 with QX 30mm fans.  Still wondering what possessed me to take on this one, although it is an interesting and unmodeled subject.  Still at the less than interesting, part cutting phase.  Most of the fuse formers are now cut out and notched, so I'll have something to start assembling soon. Preliminary CG guesstimate below, based mostly on TLAR and somewhat on the subject shown above the TU 104 at the bottom.  I've learned not to start as far aft as the at the theoretical CG point on swept wings with high taper and short chord.  Seems different for the guys with the larger scale models, versus 34" span.
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Konrad
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« Reply #51 on: October 02, 2017, 08:59:41 AM »

What are QX30 fans?
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Cut it twice and it's still too short!
Bill G
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« Reply #52 on: October 04, 2017, 12:08:15 AM »

QX Motor are a newer 30mm EDF that uses a 7000kv outrunner.  They are lighter than the heavier small 2s outrunner fans and are reasonably efficient.  They also make a 10,000kv, for those that like heavy models with larger 2s lipos.  The only issue I've heard is that they use a sheetmetal strip with magnets glued to it for the bell, presumably rolled around a mandrel and spot seam welded.  A few have come apart.  I plan to reinforce the bell with something.  At the moment I have some lipstick tubes that look promising, where I could cut and slip reinforcing rings around the bell.  Probably doesn't need much reinforcement, just a bit of added strength.  The few that came apart may have not been welded properly also.
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USch
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« Reply #53 on: October 04, 2017, 11:27:08 AM »

Put a tight row of kevlar thread around the bell and keep it there flooding with CA.

Urs
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Konrad
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« Reply #54 on: October 04, 2017, 11:33:01 AM »

Are you able to maintain the balance of the rotor using a liquid (low viscosity, runny) glue to saturate the fibers?
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Cut it twice and it's still too short!
USch
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« Reply #55 on: October 04, 2017, 11:42:48 AM »

OK, "flooding" might be misleading, actually you need only a few drops to saturate the thread. So actually you dont unbalance the bell.

Urs
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Bill G
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« Reply #56 on: October 05, 2017, 10:12:27 PM »

Are you able to maintain the balance of the rotor using a liquid (low viscosity, runny) glue to saturate the fibers?
Exactly why I'm not going that route. 
They seem well balanced from the factory.  While a few have exploded, I don't want to create another problem, while curing one that may not even exist.  Spent many hours balancing/clocking fans.  Nice to avoid it, when possible.
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