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Leave it to me to find something else to go wrong

Old 05-17-2005, 08:53 PM
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Skynyrd Man
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Default Leave it to me to find something else to go wrong

[:@][:@]Well, this was not how I wanted to show you how the new covering looks.
Yesterday I flew it for the first time, I had just replaced all the plastic clevis connectors with metal ones and as soon as I got in the air I lost control of the throttle, I flew it around at full throttle till I ran out of fuel and made a good dead stick landing.
Upon investigation I found that the clevis connector and the push rod were no longer connected the threads on the clevis connector just slid over the threads. I grabbed a new clevis connector and it seemed to thread on tight so I replaced it thinking I must have a bad connector.
Tonight I went back up, was doing loops, rolls if you want to call them that and I even did a bit of inverted flight. I was having a ball.
After 10 minutes I decided to do a couple of approaches, on the first one a throttled down and did a nice low fly by and gave it throttle to come around again. All of a sudden it went full throttle again with no throttle again. I took it up high to run it out of gas and do a dead stick. I finally ran out of fuel and started to bring it around. I'm not sure what happened but somehow I became disoriented. By the time I figured out were I was I was to low to bring it back so I turned it away from any possible neighbors and steered for the field across the street. Only problem is before I could try a long distance landing I lost it behind some trees. It ended up smack dab in the middle of a 400 acre field. At least it was a good job of getting away from the neighbors. Damn long walk though.
Again the clevis connector disconnected from the push rod. I checked it and clevis connector just slid in over the treads. About this time I am thinking I am raising some holy hell with the LHS and the manufacturer clevis connectors .
Just for giggles I tried putting the bad clevis connector on a new push rod, it threaded on nice and tight.[:'(] I don't know what to think now, other than I will replace the push rod and go back to plastic clevis connectors on the throttle

Damage, ouch. costly![:@][:@]
Looks like I lost the receiver and a servo. the needle valve on the Evolution is broke. The plane looks like a easy fix, I'll need a new firewall as that shattered.
Stick around for my next new way of crashing.[:@]
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Old 05-17-2005, 09:01 PM
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Rubberduck
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Default RE: Leave it to me to find something else to go wrong

Holy eerie similarities Batman! I just had flashbacks to my Alpha crash when I saw the picture of your Evo motor with the innards strung out. Here's the picture from my crash for comparison...

Sorry 'bout the crash...not sure what to say about the clevises...
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Old 05-17-2005, 09:05 PM
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JohnBuckner
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Default RE: Leave it to me to find something else to go wrong

Using a metal clevis on a metal throttle are if that is what you are doing if a very poor plan as you found out the high vibration at that point will cause the threads to erode and the rolled seam to open imperceptably.

Even worse is the RF noise that will be generated at this point as the clevis pin wears the hole in the throttle arm. Its not a question of if it will cause the loss of your airplane but only when. Never use metal to metal on a throttle arm.

John
Old 05-17-2005, 09:08 PM
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Skynyrd Man
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Default RE: Leave it to me to find something else to go wrong


ORIGINAL: JohnBuckner

Using a metal clevis on a metal throttle are if that is what you are doing if a very poor plan as you found out the high vibration at that point will cause the threads to erode and the rolled seam to open imperceptably.

Even worse is the RF noise that will be generated at this point as the clevis pin wears the hole in the throttle arm. Its not a question of if it will cause the loss of your airplane but only when. Never use metal to metal on a throttle arm.

John
What gives? I could have swore I read somewhere on here they were superior.
Old 05-17-2005, 09:11 PM
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TexasAirBoss
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Default RE: Leave it to me to find something else to go wrong

Did you put a metal clevis on each end of the pushrod ? That would be a no-no. Vibration will cause it to spin and back out of one clevis or the other. One end of the pushrod should be a Z-bend or something that can't spin around.
Old 05-17-2005, 09:14 PM
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Skynyrd Man
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Default RE: Leave it to me to find something else to go wrong

Nope, it could not spin. It (for lack of a better term it stripped, expanded)
Old 05-17-2005, 09:18 PM
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Default RE: Leave it to me to find something else to go wrong

Well then , I give.
Old 05-17-2005, 09:23 PM
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Default RE: Leave it to me to find something else to go wrong

Many metal clevis have a seam right down the side (take a look). Now if you hook that directly to the the highest vibration point on the aircraft then the seam can open and threads erode.

Metal to metal on a throttle arm (that metal pin in a loose metal hole) has historically been responsible for more mysterious losses than you can imagine. Years ago when our Rx's had far less signal to noise selectivity, This was a major problem and no metal to metal was SOP. Any two pieces of metal vibrating together at high freqency will without a doubt generate noise (RF noise) that will eventually interfere.

Our modern Rx's while much more selective are stiil vulnerble to this noise when conditions are right. I have seen losses due to this constantly. When new student shows up with this setup that airplane does not fly with me untill its eliminated . Never use a metal or metal pinned clevis on a metal throttle arm.

John
Old 05-17-2005, 09:27 PM
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Skynyrd Man
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Default RE: Leave it to me to find something else to go wrong

Put another lesson learned in the memory bank.
Old 05-17-2005, 09:59 PM
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Default RE: Leave it to me to find something else to go wrong

/
Old 05-17-2005, 10:00 PM
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Skynyrd Man
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Default RE: Leave it to me to find something else to go wrong

The more I think about it the salesman at the LHS was the one who told me they were superior. I asked for plastic and all they stocked there was metal ones. Maybe I'll raise some heck with them.
Old 05-17-2005, 10:31 PM
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txaggie08
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Default RE: Leave it to me to find something else to go wrong

i rigged almost all my stuff with z-bends(throttle related anyway). good tried and true method according to the instructor...
Old 05-17-2005, 10:45 PM
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Default RE: Leave it to me to find something else to go wrong

Good news on the damage. The receiver works, it turned out to be a broken wire on the battery. Lost one servo.
Every thing in the compartment came loose in the crash.
It looks like I will have to take the engine apart and clean the dirt out before I try spinning it.
What is the best to use for cleaning an engine. Any tips.
I think I will wait till I take it to the LHS first. That burns me, he knew I was a newbie. I asked him for help finding an instructor. If they were worth a darn they would have told me not to use these things on the throttle.
It's the only hobby store for 60 miles too.
Old 05-17-2005, 10:55 PM
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Default RE: Leave it to me to find something else to go wrong


ORIGINAL: txaggie08

i rigged almost all my stuff with z-bends(throttle related anyway). good tried and true method according to the instructor...





Z bends are indeed good tried and true methods for many airplanes but are asking for trouble if used at the point the pushrod connects to the carb throttle arm - metal on metal at a loose fitting hole will induce radio interferance at some point in time, if not now somewhere down the line as the hole wears.

Your decision

John
Old 05-17-2005, 10:56 PM
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Default RE: Leave it to me to find something else to go wrong


ORIGINAL: Rubberduck

Holy eerie similarities Batman! I just had flashbacks to my Alpha crash when I saw the picture of your Evo motor with the innards strung out. Here's the picture from my crash for comparison...

Sorry 'bout the crash...not sure what to say about the clevises...
Hey Rubberduck,
Did you get your engine running again? I cant find that part that holds the needle valve on the engine on Horizons site.
Old 05-17-2005, 11:05 PM
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Default RE: Leave it to me to find something else to go wrong

Hi Skynrd Man,

Many ARFs have metric puch rods that are a smaller diameter than a 2/56 clevis. The Clevis will seem to screw on but under load the rod can move inside the incorrectly fitting thread of the clevis as they are different sizes.

It is quite ok to use a metal clevis on the throttle if the arm on the carby is non metallic. The metal to metal of clevis and metal throttle arm is what causes the problem of RF interference.

When you say you have lost the servo did it go missing in the prang or is it nolonger working? Most often the gears are stripped and you can get replacement gear sets cheaply, much cheaper than a replacement servo anyway.

With regards to the motor what ever you do don't turn it over until you have stripped and cleaned it. Usually removing the carby and the back plate and checking there is not grit after washing in fuel or solvent and brushing with a soft small brush is sufficient. In extreme cases it may be necessary to fully strip down the motor. Don't just blow with high pressure air as this simply forces grit deeper into the innards of the motor.

Good Luck,

Colin
Old 05-17-2005, 11:10 PM
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Skynyrd Man
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Default RE: Leave it to me to find something else to go wrong

Campbec, thanks for the reply. The servo does not try to move at all. Can that be repaired also?
Old 05-17-2005, 11:16 PM
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Skynyrd Man
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Default RE: Leave it to me to find something else to go wrong

Also, I have a gallon of WD-40, can I clean the engine with that?
Old 05-17-2005, 11:25 PM
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Default RE: Leave it to me to find something else to go wrong

Hi,

Can you move the control arm on the servo by hand or is it locked up? Does the servo make a noise but the arm doesn't move? Can you move the arm by hand but it seems to jump from resistance to no resistance. These are symptoms of damaged gears. In these cases undo the four screws that hold the sevo together and visually inspect the gears. If they are missing teeth or have bits jammed between the gears order/purchase replacements from the servo manufacturer and replace. If there is no movement/noise when connected up to the RX it could be as simple as a damaged connection or wire. If I repair these I always mark the now suspect servo and only use on throttle as nowdays the cost of replacing standard servos isn't as scary as it used to be.

WD40 which is mostly diesel is fine for cleaning the motor.

Cheers,

Colin

Old 05-17-2005, 11:32 PM
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Skynyrd Man
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Default RE: Leave it to me to find something else to go wrong

I can't move it useing any method, I'll take it apart and check it out. I do have a couple extra also.
Thanks again.
Old 05-18-2005, 01:47 AM
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Default RE: Leave it to me to find something else to go wrong

Do you use locking nuts on the Rod/clevis? Don't know if that would have
helped, But I thought nuts had to be used?? On your servo, most likely a
bad gear... And it is true on the medal to medal... Your model fuel works
good to clean out the engine...
Old 05-18-2005, 08:36 AM
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Default RE: Leave it to me to find something else to go wrong


ORIGINAL: Skynyrd Man


ORIGINAL: Rubberduck

Holy eerie similarities Batman! I just had flashbacks to my Alpha crash when I saw the picture of your Evo motor with the innards strung out. Here's the picture from my crash for comparison...

Sorry 'bout the crash...not sure what to say about the clevises...
Hey Rubberduck,
Did you get your engine running again? I cant find that part that holds the needle valve on the engine on Horizons site.
These are the parts that I bought when I had my crash:

http://www.horizonhobby.com/Shop/ByC...dID=EVO100E46B
http://www.horizonhobby.com/Shop/ByC...dID=EVO100E46C
http://www.horizonhobby.com/Shop/ByC...odID=EVO100416
http://www.horizonhobby.com/Shop/ByC...dID=EVO100870A

If you can save the gaskets, then you wouldn't need to buy the gasket sets. But I'm of the mindset that whenever you take something apart that has a gasket on it, you replace the gasket. (I grew up around an auto-repair shop, and that's what we did when tearing engines down and building them back up - so that's why I think that).
Old 05-18-2005, 09:04 AM
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Default RE: Leave it to me to find something else to go wrong

Skynyrd Man- Buy NEW 2-56 pushrods from the LHS, then you will know they are NOT metric and they should work OK with your metal clevis's. BUT do not use metal clevis on throttle end if throttle carb arm is metal, use nylon. I have had supposedly good quality metal clevis's strip on me before and have stopped using them. This is a personal thing, others swear by them- I swear at them (sometimes). I've been using these in a lot of places lately where there is room as they are a little more bulky but solid.

http://www2.towerhobbies.com/cgi-bin...?&I=LXWH32&P=7
Old 05-18-2005, 09:18 AM
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RCKen
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Default RE: Leave it to me to find something else to go wrong

Well I guess I'll be the odd man out. On most throttle setups I use 2 EZ Connectors [link]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXAHE6&P=ML[/link] and braided wire. I put solder on the last 2"-3" of the braided wire and put that through the EZ Connectors. I use this setup because it won't "rattle" loose at the engine end, but it's easy to adjust because of the EZ connector. I can't count how many planes I've used this on, and never had a problem with it at all.

Hope this helps.
Old 05-18-2005, 09:51 AM
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Default RE: Leave it to me to find something else to go wrong

Thanks for the links everybody, I will get this changed over. I guess since I don't have the benifit of an instructor or a knowlegeble LHS I will just need to ask you guys before I do or change anything on my plane.
It's just frustraiting, it seems most of my problems are little technical things. Like metal a clevis, Not raising my anntena, not being able to get an engine to run and tx boxes burning up fuses. My flying itself has improved though, guess I just need to learn the little things to keep me in the air.

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