RunRyder RC
 4  Topic Subscribe
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1152 views
Scorpion Power Scorpion Power
HelicopterGasser Model RC HelicoptersOther › Starting the mods for my Predator...
12-26-2008 01:53 PM  8 years agoPost 1
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Hi all, hope Christmas went well for you...things were pretty quiet here.

I have started to pull my Predator apart to do the mods with the X frame and the main gear hub.

Which is the easier route to take to get at the X frame?
I was wondering if its easier to remove the whole front assy to chop the top of the X frame.

Something I forgot to mention before was that I had a crack start to develope on one of the side frames...the right side front to be exact...it was leading up to the larger diameter bolt that goes through the frame and into the engine crankcase.

I also had a bolt on the horizontal fin stabiliser/boom support clamp fail before now.

Would the crack and the bolt failure indicate a high frequency vibe?

I have about 70 hrs total time on this airframe, maybe more.

Thanks for any help, I am determined to get this machine ironed out.

Rob

PM  EMAIL  Attn:RR  Quote
12-26-2008 02:19 PM  8 years agoPost 2
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Oh dear, just discovered the left side of the crankcase itself has a crack. its right where the lower mounting bolt is located.

Could be grounded a while!

can this stuff be TIG welded at all?

Rob

PM  EMAIL  Attn:RR  Quote
12-26-2008 04:01 PM  8 years agoPost 3
pgkevet

rrKey Veteran

Wales

My Posts: All  Forum  Topic

Oh dear, just discovered the left side of the crankcase itself has a crack. its right where the lower mounting bolt is located.
Is that structural to the crankcase or just it's mounting? If the latter then it may be possible to use that 2-part epoxy steel stuff chunked around it to repair/support.. supposedly has been used to fix engine blocks.. and can be drilled etc..

pgk

PM  EMAIL  Attn:RR  Quote
12-26-2008 06:04 PM  8 years agoPost 4
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

My opinion is send the engine in for some service. I've seen those cracks before but in my case I think it was due to spinning the engine too fast and possibly too lean overheating it. Caused a silent auto with 8 pounds of camera gear hanging on the skids. Good thing there was a strong breeze. Anyhow engine was replaced.

PM  EMAIL  GALLERY  Attn:RR  Quote
12-26-2008 06:37 PM  8 years agoPost 5
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Well the trouble is I have to send the thing back to the UK. I might carry on running it for now...and will carry out an epoxy repair as suggested.

Well the frame mod was easy enough, I used my dremel type drill...and using a long shafted diamond cutting wheel I managed to get right in there to chop the part of the frame out.

Much easier and less time consuming than removing the whole front of the heli!

I have got the fan on a balancer at the moment...it does appear to be slightly out of kilter.

The clutch shoes are slightly out too...I plan to balance both items on their own then assemble them and recheck the balanc again....is this a good idea?

Thanks you guys, this really is a tip top site

Rob

PM  EMAIL  Attn:RR  Quote
12-26-2008 06:54 PM  8 years agoPost 6
pgkevet

rrKey Veteran

Wales

My Posts: All  Forum  Topic

If talking about the balance of the items as opposed to runout.... then I'd agree with balancing the fan if you have a good highpoint balancer. but the clutch may not be so useful...there may be some slight difference in how open the slots are which would affect it's static balance but make little difference when engaged evenly...?
..and you may affect that adversely

pgk

PM  EMAIL  Attn:RR  Quote
12-27-2008 12:14 AM  8 years agoPost 7
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Right...the fan is looking good...got it all balanced out. The clutch needed a bit taken off as there was a pronounced heavy side to it.

Trying to get the fan all nice and snug but there is a fair bit of runout.

What is the best technique? I have tried tightening it down...not too tight...but lifting the fan yet again and turning it on the spindle again it seems I am chasing the runout error.

Getting fed up now, off to have a few drinks and call it a night

Rob

PM  EMAIL  Attn:RR  Quote
12-27-2008 01:47 AM  8 years agoPost 8
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

Here's what I did and I got a pretty good runout

http://runryder.com/helicopter/t431094p1

PM  EMAIL  GALLERY  Attn:RR  Quote
12-27-2008 12:03 PM  8 years agoPost 9
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Thanks very much for the link there, that helps me a lot.

Going to find me some epoxy steel type stuff to temporary repair the crankcase for now. Will let you know how smooth she runs soon!

Rob

PM  EMAIL  Attn:RR  Quote
12-27-2008 09:11 PM  8 years agoPost 10
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Well I have just test run the Predator, minus the main gear etc...just on idle with a little rev here and there to engage the clutch.

The vibes are less now, but still there. I realise full well that a gas motor is going to produce vibration...but how much...what limits are there?

Rob

PM  EMAIL  Attn:RR  Quote
12-27-2008 10:39 PM  8 years agoPost 11
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Just got back from a quick hover about...one of the boom supports decided to let go...snapped for some reason or other...wonder what else is going to crack or fall off?

Found an interesting thing, probably related to the main gear hub mod...which I have yet to carry out...but its not a huge job.

While picking the Predator up and presenting it nose up to the wind the head started to turn...autorotation...I like messing about doing this...BUT! something caught my eye:

as the head was turning along with the tail drive/crown cog I noticed an uneven plane of rotation, between the alloy crown hub and the main gear, which was stationary.

About to pull the thing apart to take a look..would this be the wobble that the hub mod fixes?

sorry to sound a bit dim, it would be a treat to stop the tail from bouncing about...tempted to flog the thing and get another Trex 450

Rob

PM  EMAIL  Attn:RR  Quote
12-27-2008 10:53 PM  8 years agoPost 12
smallplanes

rrElite Veteran

S.C. ,SSA

My Posts: All  Forum  Topic

I balanced my fan today(alum fan)and man was that thing a pain in the butt,it's not perfect but almost. I put my fan on the taper on the motor and it was running out about .015 thou,i just started turning it on the crank and got it within about .005,,so i took the bolt back out and put red locktite on it and tightened it down,,it went out to about .008 i then took a plastic hammer and hit it several times until i got it to lease than.001 and thats where i left it. I bolted the clutch shoe on and checked the inner diameter and it was less than .0015 so thats where i left it. I'm going to bolt the motor in and hope for the best. Hope this helps.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
12-28-2008 12:07 AM  8 years agoPost 13
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Yes, its frustrating. I ended up making a steel plate fit to the engine block using one of the exhaust port bolt holes...at the top I had a nut and bolt assy to hold the dial indicator...worked a treat.

I have the main gear hub out now, going to wait till tomorrow to squeeze the outer sleeve..or the inner sleeve out of the crown gear assy and do that trick as mentioned in the Mod for this area.

I just hope this will calm the tail down...its a bit better already with the balanced fan...the vibes are a lower frequency.

I like the Predator, cheap to run and flies well enough.

Must admit to wishing I had spent a bit more and got a Vario or a Bergen.

I cant knock the Predator too much though, for its price its a gasser and it can also provide a chassis for a turbine.

Rob

PM  EMAIL  Attn:RR  Quote
12-28-2008 05:59 AM  8 years agoPost 14
Billme

rrElite Veteran

MS

My Posts: All  Forum  Topic

If you will add the shim and o ring to the auto hub, and pull your tail rotor torque tube to make sure your bearings have not come out of the holders, you might see a big difference..
Make sure you have your throttle setup correctly

PM  EMAIL  GALLERY  Attn:RR  Quote
12-28-2008 12:39 PM  8 years agoPost 15
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

Hi Billme, it was lucky of me to find that wobble.

I wonder just how long its been there, the crown gear sleeve that goes into the main gear one way bearing is not right.

Its not perpindicular (forgive my spelling)to the crown gear hub. I am going to push it out of the hub and reseat it and see if this helps.

The torque tube is pretty good, I pull the tube every couple of hours to check all is well...plus to grease the tail drive box gears.

The Kyosho Nexus had a problem with its torque wire drive spacers working loose as well, this was my first heli.

Is there an ideal throttle range? I had it linear for a long time but have knocked the curve back a bit to see what happens...still bags of power.

Thanks for your help in this, I have much to learn!

Rob

PM  EMAIL  Attn:RR  Quote
12-28-2008 02:09 PM  8 years agoPost 16
smallplanes

rrElite Veteran

S.C. ,SSA

My Posts: All  Forum  Topic

The nexus was my first hel also,i never learned to fly it,,just to crash it.I sold it and went to planes flu them for about five or six years and about two years ago my wife bought me a blade cp for Christmas. I got a sim and flu helis on there for about a month before Christmas and when i got the heli the very first day out i flu figure eights and landed it all by myself. I flu it for about a month and got a trex 450xl and i flu it the first time out. The sim has help me a great deal,i was doing loops rolls and some inverted hovering the second or third time i flu it.I then bought a Evo 50 which is a lot better flying heli than the trex and so far i hav e not crashed the 50 due to pilot error. I bought a second evo 50 and on the third test flight it went out of control(tail servo quit) and it hit the dirt and it cost me $250 to get it back flying but i did not let that stop me. So now i've gone to a Bat 26cc gasser i'm still in the build so i've not got to fly it yet,i hope all goes well. Last night i had to indicate the clutch bell in it was running out about .008 i got it to within .001 so now i have to put it back in the heli so i can put the motor in. I wanted to get the preditor but i could not find one so i went with the bat pro and i'm glad i did,its a very nice heli,very well made a GREAT support. I hope you get yours flying good and let us know how it goes,i want to know?
Good luck.

Thanks

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
12-28-2008 02:24 PM  8 years agoPost 17
Billme

rrElite Veteran

MS

My Posts: All  Forum  Topic

This may be one of your problems, you have been running a linear curve...When you force a gasser to run at a higher rpm (without the engine timing changed to except this) plus more power than the blades require, then the engine will dismantle the mechanics no matter who made them...
You can not run a linear curve with a gasser...According to how your mechanical setup is will determine how well your curve will look...

Someone direct this pilot to the setup of the throttle...

What blades, and gear ratio are you trying to run..I forget what engine you are running 231?
Bill

PM  EMAIL  GALLERY  Attn:RR  Quote
12-28-2008 03:12 PM  8 years agoPost 18
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

I am humbled on a daily basis.

Well this Predator was built about 2 years back. The manual was pretty scant on setting anything up...so I naively thought to go for the linear power setup.

I have knocked the power range back but am guessing about, for one thing; a tank of fuel now lasts 40 mins as opposed to 30 mins or so on the original setup.

Not sure on the ratios but this heli has its gearing as supplied in the kit, Yes its the 231 engine.

I have sorted the tail drive crown problem....had to push the sleeve out...not realising that the very end is threaded...but its all back together now with the locktite setting....I shimmed the space between the alloy hub of the crown and the hub of the main gear...so it sits evenly as it sets. I will tighten the grub screws a little more once the locktite has set.

Thanks for your help, I would have been chasing these problems forever more without you.

Rob

PM  EMAIL  Attn:RR  Quote
12-28-2008 04:35 PM  8 years agoPost 19
Billme

rrElite Veteran

MS

My Posts: All  Forum  Topic

I think newbies would be better off using a gov from the beginning, this would help keep them out of trouble...

How to find a throttle curve?

You need a rotor tach to do it, and if you don't have anyone to help you, you can do it this way:

With your radio at the throttle curve, and engine running, move the stick to quarter throttle...Move that point up till you hear a change, and tach the rpm..Move the point up till you get within a hundred rpms of your target rpm..Now from here on, your going by sound of the rpm because you can't hold the tach, and fly at the same time..
First, you know that when you move the stick higher, you might as well move the next point down, because your previous point is already near your target rpm..Bring the heli into a hover..Did you hear a noticable increase? Did it sound like the same rpm on the ground?
Now move the stick to 3/4's, and watch it climb out, did you hear a change?, move that point that corresponds to that position, and move it to correct the change...
If your radio will allow, assign those points to your hover knob, and then you can adjust the rpm anytime, without going to your curve...
If you plan to use idle ups, then you need to adjust the engine for the highest rpm you plan to run..You can do this in normal, and with the knob.. Just transfer the numbers to the idle up, and when your finished, just go back to normal, and adjust the knob for a lower rpm..
You can't go to low, because the gas engines don't like two speed setups, so long as you don't have to big of a change..
Good luck,
Bill

PM  EMAIL  GALLERY  Attn:RR  Quote
12-28-2008 07:24 PM  8 years agoPost 20
predatorman

rrVeteran

Falkland Islands

My Posts: All  Forum  Topic

So the aim is to match the rotor torque with torque from the engine?

I understand that. Its easy to overpower the rotor with the available power that a gas engine can dish out.

So waht I am listening for is 'droop' or a load on the drive train.

Ok, I will patch my faithful machine together and go try out what you suggested.

An optical tacho would be nice, but finding anyone to help is near on impossible.

The radio is a Futaba T7C, and it allows a certain amount of hover throttle adjustment...I think its in the wrong place though...the knob that is...needs to be somewhere easy to touch when holding the radio and using the sticks.

The governor is a nice idea, but to be honest I would rather keep the system nice and simple.

BTW...what headspeed would I shoot for...if I could ever tacho the thing? I do general flying around, some yanking and banking and carrying a small camera around...and thats about it.

Rob

PM  EMAIL  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1152 views
Scorpion Power Scorpion Power
HelicopterGasser Model RC HelicoptersOther › Starting the mods for my Predator...
 Print TOPIC  Make Suggestion 

 4  Topic Subscribe

Saturday, November 18 - 12:59 am - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online