Servo failure? (Big Predator)

[heidi-hi25]

Hi Rob,i found it a pain having to check the battery constantly,like you say a gasser out of control would be a nightmare.I use a 20c 11.1 volt.through reg will handle up to 25 volt inputs and deliver at 3 amps.The Millenium really flys well,am really pleased with it as a budget conversion.think it would perform with some of the best.Can afford to add some nice equipment to make it even better because of the low initial outlay.

[hawkman]

Well the LiPO thing is a nice compromise, I already have a charger but it lacks the balance thingy, so might have to buy another charger unit.
I would like a Generator, they are available. If you are keen on that idea then just let me know. Its cost is about the £100 mark...maybe slightly more. I just think for that price the double lipo etc would be the better option.

What I love about gassers is the simplicity of it all, just charge up...fill up...and carry radio and heli out to field and go

I started flying a nitro heli recently, had it for ages and never flew it before...its quite funny going through the procedure of getting it started lol

I see some Lipo/regulator packs have an onboard glo plug facility, quite a handy idea.

Have you done any filming with your gasser then?

Rob

[heidi-hi25]

Hi Rob,i have seen the generators but i cannot see where the £100 goes.I am an automotive engineer and the component cost for that set up looks minimal.With the amount of time the lipo batteries last and the cost(i paid £30 for pair of batteries)These high output batteries last forever with such a small drain.My Millennium has both the pull and top starts and as you say it is so easy with gassers.A friend of mine is in the process of building a Predator and i will probably get the job of setting it up.If you have any thoughts on set up(Pitch and Throttle curves would be much appreciated).Have never really thought about any camera work as yet.Be nice if on board camera was capable of transmitting live pics to a laptop.A pilots eye view would be great.Regards Mike.

[hawkman]

Hi there, please mail me with any Predator questions. I have some experience with this type...I have been flying mine for about 18 months now.

The manual is crap, it shows the build ok but the finer points its a bit lacking...unless its changed.

The most crucial point is about the tail gears...the book shows these shims that are installed on the output shaft...its misleading because the bearings can get overloaded.

The trick is to assemble the gearbox halves...just hold them together...and take the output shaft and see if it has some end play...if so then thats fine....if not the bearings will get ruined.

Century bearings are rubbish, try Boca Bearings...they sell bearing kits for quite a few helis including the Predator.

The other concern is the Mainshaft end float...the bottom bearing is a plain ball bearing..it does last a while...I have just changed mine. Make sure to add a shim if needed...you dont want any floating as the main shaft can rise and close the meshing of the tail drive take off cog...this cog needs backlash so closing the distance will ruin things...I didnt have a failure as such but with the pressure the tail drive cog will bear up causing its front bearing to overload...mine jammed and started to wear the shaft end..I used solder and some 'machining' to build it back up...didnt have the parts

Worked a charm.

Also be careful of the tail drive shaft key way...it needs to go back further...I used a file to adjust this...where the cog sits is too close to the main shaft...so the backlash is almost non existent.

Please e mail me on: robwilkinson@horizon.co.fk this will be better as I can send pics of the parts etc.

Rob

[heidi-hi25]

Hi Rob,its small details like you have mentioned that make all the difference to a good or bad outcome ,as far as building the heli goes.Will definatly be in touch when the build gets under way(he is building his T Rex 600 at the moment and several other RC projects.My E-mail is hls104@tiscali.co.uk.If you get stuck trying to get something in UK let me know.

[hawkman]

Yes, I agree.

The instructions mention locktiting everything, but I would not agree with some points. The red stuff is truly nasty and is obviously for items that will never come apart again. The blue stuff is ok if used sparingly.

Its worth taking the time to make sure the fan and clutch assy are balanced...once they are fitted its a big job to extract the engine again.

I dont like the battery tray assy, its rubbish. It could do with struts to improve it...being so long it must amplify vibes.

Its a good heli otherwise, very cheap to fix. I get all my parts from the USA so its all half the UK prices...I will shop from the UK only if its urgent...the USA can take a while for shipping otherwise.

Another good point is with the tail torque tube drive...it works well but the spacers need to be checked...make sure they dont slide...I use a dab of super glue on the shaft and spacer...same again for the spacer and bearing..only a dab...once it drys make sure the bearings can still turn...I stuffed mine up with too much glue

The O rings that go onto the spacers are not a good size...I use the heavy duty boom...the thin o rings are too thin, I use the thick ones and shave them down a touch so they are a nice snug fit.

I like the Airframe in that a turbine can be installed easily. I would love to do this but the expense is a bit too much...once I crack 45 gallons of petrol with my current Heli then I might consider it.

Rob