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June 18, 2019, 14:20:45 PM

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Author Topic: Hotliner Props - Not what they seem?  (Read 798 times)

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Offline Bad Raven

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Hotliner Props - Not what they seem?
« on: June 25, 2018, 19:49:55 PM »
After many flights, the other day I damaged the std prop on my Durafly EFX Racer, my fault, botched dolly launch in zero wind. Where it broke also damaged the cheap supplied spinner.

I'd been toying with fitting a folding prop, so this was the opportunity.

Used a "named" commercial product, original fitment to a ARTF hotliner, spinner/blade holder with Graupner CAM 7.5x4 blades (so decent quality products, not budget items, and marginally smaller pitch than the previous supplied fixed prop)

On Saturday I flew three batteries though it in this form, hand launching myself. I was really pleased with the change, easy to launch, great acceleration, flexible throttle control and a good top end.

Today on the first battery I took off and on the second circuit opened the taps from about 3/4, to a burst of "wind" noise and loss of acceleration, it promptly going quite rear CG biased.

It took three deadstick circuits to slow it sufficiently to land, plenty of time to see it no longer had a prop or spinner.

Now for the punchline, on recovering it from the grass strip, while the prop, cross brace blade holder and spinner were missing, the retaining nut and 10mm washer were still on the 5mm threaded motor shaft.

The cross unit and spinner must therefore have "exploded".

I searched the stubble (ex hay) field but could not find any parts to show the actual failure mode.

All I can say is:-

1. I paid good money for the parts.
2. I checked balance
3. The item ran smoothly and quietly under test.
4. RPM was no more than its original purposing.

At least the plane survived.....................

The user formerly know as Bravedan........... Well if Prince can do it....................

Offline dickw

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Re: Hotliner Props - Not what they seem?
« Reply #1 on: June 28, 2018, 09:13:18 AM »
At least it all went as one which could be regarded as a safety feature  :). Losing only one blade can shake a model to pieces.

I have flown “hotliners” for many years and have always used folding props with metal blade holder/centre pieces as I don’t trust plastic to stand the stresses involved at motor on or braking (unfolding / folding). 

You don’t say what brand it was, but was yours a plastic blade holder/centre piece? Some of the ARTF so called hotliners are actually quite mildly powered, whereas the EFX Racer can be quite hot by comparison.

My favourite for the lower powered hotliners is the Aeronaut range of props and spinners as I have had success with these over many years:-

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Offline paulinfrance

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Re: Hotliner Props - Not what they seem?
« Reply #2 on: June 28, 2018, 14:16:50 PM »
Same as you, I only use the metal Aeronaut ones, and never a failure,,,
Mode 2 THE only way to fly


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