Loss of Control!! (PICS ADDED)

[DaddySundown]

I have finally got to race my new 7.5 CMB LaFluer set up on my HTB 360. Futaba PCM radio.

This boat really hauls but when it peaks at top end I lose control.

The first time I lost control I was coming out of last turn and headed down the front stretch and just before the start finish buoy she lock in and I couldn't slow her or turn her. She was headed for small floating bridge (steel pipe and wood). This as a very helpless feeling and with my fail safe on I turned off the transmitter. No help. All of a sudden she turned left slightly and stuck in the mud bank and stayed running wide open with the engine still in the water. I figured it would still be getting water. I turned the radio back on with no help. I got off the drivers stand and started toward the boat. I kicked the transmitter off and back on again and I was able to control the throttle and shut it down.

There was only minor damage. I checked radio and everything was working. I am not liking this. For the next heat I replace the PCM receiver with a new one, changed the battery and checked the fail safe. All was working fine.

Next heat I ran the boat easy and being no competition I was cruising to victory. Coming around the last turn the last time I really nailed it for show. She was really cookin and all of a sudden it turned and headed right at me on the drivers stand. I could not control anything. Everyone jumped back. She hit the railroad tie that was about 2" out of the water, popped up and hit the next railroad tie, bounced off it and landed back in the water face down.

The boat believe it or not was not hurt but the K&B lower broke at the mount. The only thing holding the engine on was the throttle cable. Broke the Bob Violet 3rd channel needle, bent the steering arms, threw the battery out of the radio box and into the pond.

I have ran this boat 2 times before at my test pond and once at the race in KC, MO race with no control problems.

This has me baffled and afraid to race it at the Internats in Jackson.

What should I do?

Alan.......

 

[topfuel443]

Not sure what to tell you Alan....

All I know is when I see you running your 40 boat, Im getting in the trailer....

Sorry man, couldnt resist.

see ya at the nats.

~James

 

[DaddySundown]

Before the second heat I did check for any type of RF interfearence such as metal to metal.

 

[VansRacing]

I have finally got to race my new 7.5 CMB LaFluer set up on my HTB 360.  Futaba PCM radio.
This boat really hauls but when it peaks at top end I lose control.

The first time I lost control I was coming out of last turn and headed down the front streach and just before the start finish bouy she lock in and I couldn't slow her or turn her. She was headed for small floating bridge (steel pipe and wood). This as a very helpless fealing and with my fail safe on I turned off the transmitter. No help. All of a sudden she turned left slightley and stuck in the mud bank and stayed running wide open with the engine still in the water. I figured it would still be getting water. I turned the radio back on with no help. I got off the drivers stand and started toward the boat. I kicked the transmitter off and back on again and I was able to control the throttle and shut it down.

There was only minor damage. I checked radio and everything was working. I am not liking this. For the next heat I replace the PCM receiver with a new one, changed the battery and checked the the fail safe. All was working fine.

Next heat I ran the boat easy and being no competition I was cruising to victory. Coming around the last turn the last time I really nailed it for show. She was really cookin and all of a sudden it turned and headed right at me on the drivers stand. I could not control anything. everyone jumped back. She hit the railroad tie that was about 2" out of the water, popped up and hit the next railroad tie, bounced off it and landed back in the waterface down.

The boat believe it or not was not hurt but the K&B lower broke at the mount. The only thing holding the engine on was the throttle cable. Broke the Bob Violet 3rd channel needle, bent the steering arms, thew the battery out of the radio box and into the pond.

I have ran this boat 2 times before at my test pond and once at the race in KC, MO race with no control problems.

This has me baffled and afraid to race it at the Internats in Jackson.

What should I do?

Alan.......

106671[/snapback]

​

Alan,

If it only does it at WOT, then it may be resonating something on the boat causing interferance. Check to see if you have anything metal to metal parts that could be vibrating at high speed.

We like to have a plastic link somewhere between the engine and the servo. Having a complete metal steering system from the engine all the way to the servo horn can cause some weird stuff to happen sometimes.

Just some things to check...Hows the Lynx running?

-Carl

 

[David Homer]

I concur with the resonance theory, but my guess it is affecting power connections... remember, no fail safe will work if there is no power!! What I would do is replace the switch harness, then hook up a voltmeter to your battery pack and try twisting the pack around some. The voltage reading should range between 1.2 and 1.5 volts per cell, and it should stay constant. If there is a loose tab or solder connection in your pack, vibration could very easily cause an open circuit, and no voltage output... Also if your nicads are a few years old, they can and will go south... found that out the hard way last month...

 

[DaddySundown]

I did check for any metal to metal contact before the second heat and changed the battery pack.

The radio box is attached to the boat on a cushion of silicone sealer with the battery pack in an additional attached 3" x 3" radio box in front of the factory box and also siliconed down. The 2 are attached with a 7/16" hole for passage for the battery pack leed to attach to the switch leed.

Alan....

 

[DaddySundown]

I'm gonna take another look at my steering push rod set up.

I have a push rod under the the right steering push rod that is connected to the switch. These 2 rods are about 1/4" apart. Same situation on the other side with the left steering push rod and the push rod controlling the mixture.

At WOT these 2 could possibly be touching.

Alan......

 

[Propjockey]

These 2 rods are about 1/4" apart.

That means each rod only has to flex 1/8" to touch. Harmonics could easily be the culprit.

 

[Jerry Wyss]

I had something similar like that happening on a heavily modded 7.5K&B,,was like "metal to metal" contact at WFO. After an exhausting effort to find it we decided that it was metal to metal contact, it was between the piston and the sleeve! as the engine was goin' lean right near the top of it's RPM range due to "Fuel Foaming" :huh:

 

[Tim_Duggan]

These 2 rods are about 1/4" apart.

That means each rod only has to flex 1/8" to touch. Harmonics could easily be the culprit.

106687[/snapback]

​

I put electrical heat shrink tubing on any pushrods that are close to metal. Cheap - easy and looks cool if you use the colored stuff! It is an excelent electrical insulator - thats what it is designed to do.

Also - did you try a different RX crystal when you swapped RX's? If it's JR - I'd definately try a different one - heard of that occuring before on JR.

Tim.

 

[Mike Hughes]

First off I seriously doubt that it is interferance. You said it is a PCM radio and you are using a PCM receiver. The receiver will only recognise a square wave or pulse wave. There is nothing in nature that can produce a square wave by accident. It should not glitch unless some other PCM radio is on the same channel. Since the fail safe did not cut out the throthle when you turn off the radio, that tells me you lost power. I think you have a intermittant break in one of your wires. At high speed the boat can get a lot of vibration that with cause the lost of power through the break. I would change out your switch harness. A short across the black and red wires will cause the same loss of power also.

Mike

 

[charles maley]

get some airplane reciver insulation .. 1/4 inch thick foam.. wrap it around the reciver and batterie that should solve the vibration

 

[snowdog-2112]

Daddy,

Any chance you're using digital servos?

 

[Precision Boats]

Hey DS

Sorry to here about your problems man. I'am thinking about what could be wrong.

I once had a tunnel that had radio problems no matter what we did. We replaced everything and also put it's componets in other hulls (worked fine in other hulls) it would still have the same problem when we put them back in the problem tunnel.

We finally figured out it was the hull it had to go. Alan it drove me crazy for 6 months. I am not saying this is your problem but it was ours. Take a close look at everything.

C-YA

Tim

 

[SayMikey]

Hey DS
        Sorry to here about your problems man.   I'am thinking about what could be wrong.

        I once had a tunnel that had radio problems  no matter what we did. We replaced everything and also put it's componets in other hulls (worked fine in other hulls) it would still have the same problem when we put them back in the problem tunnel.

      We finally figured out it was the hull it had to go. Alan it drove me crazy for 6 months. I am not saying this is your problem but it was ours. Take a close look at everything.

C-YA

Tim

106731[/snapback]

​

what kind of pipe mount are you using? and do you have a cable to hold your pipe in case it falls off? Ive seen such cables cause crazy things.....Mikey

 

[chriscarbon]

alan,

also change to one of your other model memories on your pcm radio. a friend had a glitch in his radio (not as sever as yours) and changing to another model mode solved his problem. his radio went back to the mfg under warranty.

chris

 

[Joe Reese]

ALAN,

You probably have herd it all....

But I had to fight this one too,

The turn must have been the furthest from your transmitter and a spray of water cousing resistance of or lost frequency. Now it dosent sound like much but if you add a reciver in a hull with foam in the Radio box laided flat mind you 1/4 inch thick and you take a cut to length and width to the reciver and take that foam not tight to it place the reciver in the radio box seal it up with tape run your boat and the darn thing runs from you!!!!!!!!!!

The reciver was not tight, posably pushed the foam back up and slid back down now, its hitting your steering or other small servos causing you to pull your hair out.

What realy should be done is try to fit the same amount of foam but make the reciver tight. Like not able to move when the servo wires are pushed into it but not to crush the plastic. Thats all you need or the battery was not cycled.

Good luck...

P.s

I wont go less the a 6.0 volts with the 1/4 scale or and type of digie steering servo and a reciver antena wire is beteen 14-22'' long.

 

[DaddySundown]

I really appreciate all the replies but I have not found the time to even look at the boat. I won't be able to until maybe Thursday. Got a meeting in Texas tomorrow and wed.

I am thinking by the replies that the switch harness may be giving me the problem.

The steering servos are 2 HS645MG Hi Tech's. The radio box in this hull is very deep. I use to of those blue paper shop towels to line the bottom of the box to gather any moisture that may get in there. I wrap my servo in the white packing foam about 2 times and use a twist tie to hold it around it. This keeps it from making any contact with anything in the box.

The pipe i rigged per Iwin's quiet pipe instructions with no safety cable.

The servos are not digital.

Mike H. I think you have hit on something there with the square wave or pulse wave.

All the equipment in the radio box including the radio box was new just last spring. Although I did find some moisture in the box about a week after I had first ran the boat causing some corrosion to appear on the servo screws and the clevis on the throttle cable.

Sure is making since that the switch harness has failed.

Alan.........

 

[Grimracer]

Allen,

Get rid of the twist ties and use Vet wrap enstead..

Grim

 

[DaddySundown]

Allen,
Get rid of the twist ties and use Vet wrap enstead..

Grim

106836[/snapback]

​

What the heck is Vet Wrap!

Is that the wrap that comes in colors and used to wrap animal legs?

Alan..