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HelicopterGasser Model RC HelicoptersOther › Starting the mods for my Predator...
12-28-2008 08:28 PM  8 years agoPost 21
pgkevet

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Wales

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An optical tacho would be nice, but finding anyone to help is near on impossible.
I'm in a similar situation and even with a sky-tach I find that borrowing other pilots generally gives as many meaningless results as people you ask! A Skytach isn't that easy to get genuinely right and folk get sloppy.

The best and most expensive option would be a downlink readout of headspeed.. if your budget allows the extravagance then it has to be ideal. Raja touts the idea of a governor and using it to tach by switching it on/off in flight to see how well your curve matches..

A simpler starting point is a reasonably priced direct tach wedged to the ground under heli and read the headspeed when it's light on skids. It's something you can do solo if it has big numbers and your eyesight is good.. but don't get too close. At least you have a rough idea of your liftoff headspeed to go from and can then try and judge flight headspeed from that.

pgk

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12-28-2008 10:05 PM  8 years agoPost 22
predatorman

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Falkland Islands

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Hi Smallplanes, I liked the Nexus. Mine lasted 16hrs total flight time....it bit the dust during an auto exercise. I was pushing my luck too far and couldnt find the throttle hold to get some power back on...and that was that. The cost of parts was going to outweigh the value of the airframe.

Next Heli was a century Hawk, not a bad heli. It was quite tough and easy to work on...got loads of hours on this.

The biggest pain was finding nitro fuel, and its expensive for what it is so the gasser option seemed the best way to go...enter the Predator! been looking at this heli for some time.

I have lost count of its flight time, well over 70 hours possibly. It was quite scary at first, commands more attention than you would think.
I like the Predator, but the manual doesnt help muhc with set up..guessing that century must think the builder has more than average experience in some ways.

Rob

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12-28-2008 10:11 PM  8 years agoPost 23
predatorman

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Falkland Islands

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Pgkevet, interesting point on the tacho.

What I could do is fix my little 'Flycam' to the heli to film an onboard tacho while I fly around.

Got the idea off a guy with a Turbine Predator, they were using this idea to get over a similar problem...a 'topping check' if you will!

I work as a fitter on real helis, if we change and engine we have to go flight testing and find out the power the new unit produces and adjust in flight as required...this is on Sikorsky 61's...nice old workhorse

Rob

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12-28-2008 10:26 PM  8 years agoPost 24
Billme

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MS

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1850 with a 6.2... If you can video it, and let me hear it, i can get you close..
Bill

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12-28-2008 10:48 PM  8 years agoPost 25
pgkevet

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Wales

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What I could do is fix my little 'Flycam' to the heli to film an onboard tacho while I fly around.
Cool idea! I wonder if one could go the extra step and video call to a second mobile....for realtime..

pgk

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12-29-2008 05:17 AM  8 years agoPost 26
Excalibur

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Destination: Earth

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Or there's this alternative - look for the third response down. . .

http://www.runryder.com/helicopter/t322195p2/

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore

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12-31-2008 05:23 PM  8 years agoPost 27
predatorman

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Falkland Islands

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Well I finally got around to a quick test flight, the weather was getting pretty bad yesterday. This morning still saw some squalls passing through but off I went anyway.

Well....the vibes have pretty much gone! the vertical fin has no sign of a vibe and the nut/bolt right on the end of the tail gear box was only ever so slightly moving...like a nervous twitch. Before the whole gearbox was a blur...now its stable...save for that slight low frequency movement.

So thanks very much Billme and others for your input. I revised the power curve quite a bit...mid stick is 30 percent...I have actually found a Tacho! its for planks but looks like the mounting will go onto a boom...so I would set it up so its out of the flybars way? setting it to two blades on its menu? Its internal battery is almost finished...wont stay on for long and I dont have a spare channel to plug it in for power.

Looks like my flight endurance could easily get up to one hour, my old power curve was seeing 40 mins or so on a tank.

I did work on the main gear hub, the crown gear was off for sure..had to reseat the inner tube so it sat straight..resorted to using some red locktite to act as a filler...will be ordering some new parts soon though so will include these parts so as the O ring mod can be carried out.

What I did find was that the backlash on the crown gear was hard to obtain...its always been that way...in fact I had to file back the keyway/flatspot on the tail take off shaft..the one within the frame end of the boom...found that the cogs allen screw was sitting right on the shoulder of the notch.
This is the only critical thing I have against the kit...it needs more shims included to get a better clearance...I filed the brass spacer down a bit (the spacer that sits between the main gear hub and the bottom bearing) got a much better backlash this way.

Well, must spend some cash on this bird and get a Jewel Generator for it

Rob

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