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Dec 20, 2019, 07:19 PM
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Has anyone found that it is necessary to cut out a significant amount of styrofoam from underneath the cockpit/pilot to keep the rudder control rod from binding? The oval plate that has two screws in it (guessing it holds the pilot in place) sits right on top of the control rod an puts a lot of pressure on it.
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Dec 21, 2019, 09:51 PM
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PikeStaff's Avatar
No. That’s a new one that you’ve discovered.....lucky you. Is the servo tray seated all the way down on the foam below? The rudder pushrod in mine isn’t happy following the arc it takes going out to the rudder, and consequently doesn’t center at all well. I sprayed some graphite up the tube, which helped, but that blasted thing still won’t move completely freely. But it is all well clear of the bottom of the canopy.

After using the rudder I have taken to just giving the stick a very gentle bump in the opposite direction - and that gets the rudder at least fairly close to centered. This is a condition that’s on the To-Do list.
Dec 22, 2019, 10:23 AM
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Thanks Pikestaff! Going to try and post some photos....

#1 is of the servo tray. Rudder servo seems okay. Check out the new tray for the wing cable plugs and sequencer! *S*
#2 is the rudder guide tube
#3 is the tube as it exits the fuselage
#4 You can see the pilot hold-down plate in relation to the pushrod.

Found that they guide tube was loose and had moved back at least half an inch. This caused the hold-down plate to be riding directly on the pushrod. This would cause the rudder to not recenter. I feel that if I had just moved the tube to underneath the plate, the rudder would still move slowly because it had a bend in the guide tube. May be worth checking out.
Jan 17, 2020, 04:01 PM
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Eek. Itís back.


OK, a while ago I added bolts to the prop assembly to see if thru-bolting both prop blade attachment points might help the explosion issue. While it seemed to do so, examination today has revealed a concerning development.

Cracks have appeared in the outer hub, radiating outward from the new bolt holes. In all fairness, I confess that this prop has experienced several prop strikes since the mod. Canít prove that this is the cause of the cracks but not difficult to think they didnít help anything either. I will disassemble the prop completely to see if there is any other cracking (i.e., the back hub half) presenting anywhere, and report back if there is.

This assembly has a good 35 to 40 flights on it, and fortunately did not come apart. I did not hear any unusual sounds from the plane in flight, either, to suggest there was something wrong. Fortunately, RCG member SnakeBT6 asked for some pics of the mod, which gave rise to the discovery. Thinking he saved my Corsairís bacon . Thanks, amigo!
Jan 17, 2020, 10:04 PM
Registered User
I like what you did there. Im almost considering using a thin coat of epoxy on mine on both sides of the hub.

Not sure? I believe Hysol will do the trick on this.

Appreciate the pictures and glad you got this before it became too late..

Us Chevy guys always helping out Ford guys lol (beautiful Cobra btw..great looking stance/rake on it.)

(Im in Jax and do quite a few track days at the Firm in Starke and on the road course at Daytona when they are available.)
Last edited by SnakeBT6; Jan 17, 2020 at 10:21 PM.
Jan 17, 2020, 10:45 PM
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. Yah. Love us some Chevrolets, too - especially the fast ones.

Don’t know if even Hysol would help here; maybe the bolts were tightened a little too much, stressing that hub more than needed. Solvent-welding the cracks would be a better approach but still a band-aid. If a metal stiffener, like the FlightLine prop uses, could be fabricated it would be a giant help. It would spread the stress across the other bolts and put an end to this misery.

Haven’t made it out to Starke yet but have been to Daytona. Guess I should bring the Cobra next time, too . We gotta get you into one - then you’d be unstoppable.
Last edited by PikeStaff; Jan 17, 2020 at 10:58 PM.
Jan 18, 2020, 01:01 PM
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Well........


The cracks essentially disappear once compression from the new bolts is backed off - and looks like 2 out of 4 reach the bolt holes, with the other 2 fading out somewhere in between. Makes me think more than ever that over-tightening had lots to do with it.

2 of the washers used to fill the bolt head cavity in the outer prop bolt hole are set out alongside the blade; theyíre pretty small . I do not see any cracks, either forming or present, in the back hub half, and thatís good as pics of the failed ones showed that hub as the big failure point. The blades themselves look excellent - no nicks, dings, or cracks anywhere. Overall, getting the feeling that this prop might well have been able to survive a while longer......provided the nitwit pilot kept the plane on its feet instead of its nose . While the prop strikes it has had werenít terribly severe, they still had the momentum of - at least - the whole turning assembly.

Have another hub, and that will replace this one, on principle. No need to twist a tigerís tail - like the plane enough not to want to lose it, especially to something stupid.
Jan 19, 2020, 02:50 PM
Registered User
There pretty awesome..Ive never even sat in one. They had a few out last time I was at Daytona.

Ill be out at Starke on the 25th. I usually go about once every 6 weeks or so.

My other hobby that takes all my money lol
Jan 19, 2020, 02:52 PM
Registered User
Im going to give the hysol a shot as it seems itll fuse it all together.

I would imagine if there is enough want over at Small Parts CNC they could make an aluminium one.
Jan 20, 2020, 12:09 AM
Twins are Twice the Fun
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Quote:
Originally Posted by SnakeBT6
Im going to give the hysol a shot as it seems itll fuse it all together.

I would imagine if there is enough want over at Small Parts CNC they could make an aluminium one.
That would be an absolute fix
Jan 25, 2020, 05:28 PM
Registered User
So I took mine out to the field today to possibly maiden. If nothing else I would do some taxi runs. Got everything plugged up and wing bolted on. Brought the gear down, flipped it over and sat it on a paved runway. First thing I noticed was that there was NO steering authority even on high rates! The runway is 45 feet wide and I couldn't even do a 180 from on edge to the other. I had also noticed the tail seemed to be sitting rather low to the ground. Got it back to the bench and noticed a bad hum from the rear. Long story short, the tailwheel retract servo was completely stripped. Keep in mind. This was the first time I had set the plane on the landing gear and it was on a paved runway so it had hit no bumps. Calling HH Monday morning but can any of you tell me about the rear steering action you are getting out of yours? Any way to increase it? Or is it possible that due to the wheel being partially retracted, I wasn't getting full throw? Thanks!!
Jan 25, 2020, 05:29 PM
Registered User
Another note. I mentioned a few posts back about my rudder not centering. The EZ link on the rudder servo arm was only hand tight! Check dem fasteners!!
Jan 25, 2020, 05:34 PM
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Quote:
Originally Posted by Corwin51
Calling HH Monday morning but can any of you tell me about the rear steering action you are getting out of yours? Any way to increase it? Or is it possible that due to the wheel being partially retracted, I wasn't getting full throw? Thanks!!

Don't laugh, I never was good at geometry. After thinking about it, makes perfect sense that I wouldn't get full throw unless the pivot point of the wheel was nearly perpendicular to the ground. Would still love to hear any input......
Jan 25, 2020, 10:30 PM
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PikeStaff's Avatar

Yep!


You got it - unless the retract is fully extended, steering will be negated due to the steering axis getting closer to parallel to the direction of travel. The steering servo is mounted up on top of the wheel frame and drives the steering thru a simple connection. The retract servo is mounted up in the fuse, and operates the movement of that retract assembly thru 2 pushrods. Each servo has only one function....either retract/extend or steer.

Once you get the retract to extend and lock into position, youíll have plenty of steering capability. Surprising the servo has stripped as the retract unit is a metal gear servo; not impossible but unusual just the same. Whatís not unusual is to find the set screw holding the pushrods to be loose - and then there is no proper retract function.

Any decent sized servo, 25 gr size, should be good as a replacement. Use the stock servo arm, or one the same length, to get the right amount of movement needed to push the retract locking bar into position at both up and down positions.

Good luck on the maiden! Itís really a great flyer - lots of enjoyment with this big foamy.
Jan 26, 2020, 09:54 AM
Registered User
Quote:
Originally Posted by PikeStaff
Surprising the servo has stripped as the retract unit is a metal gear servo;
Ahhhh....but only for the last two gears and the pinion on the servo motor.


Quote:
Originally Posted by PikeStaff
Any decent sized servo, 25 gr size, should be good as a replacement.
First thing I thought since I have several Hitec's from other projects but the casing is shorter. I'd have to decrease the length of the plastic "box" that is glued into the fuse to hold the servo.


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