Monster sized Fock-Wulf FW-42

[PsyBorg]

Kinda why I sent you the entire A frame assembly so the stance is a tad wider.

That is a lot of prop below the water line hehe. What were they planning for landing gear on the originals? Stilts with wheels? According to wiki it used 3.8m 4 blade prop (12.6 foot dia) so the 1/10th scale we are working in puts a 12 in prop in the right ball park. also says it had retractable tricycle gear but no specs on those. I will look for more pics. maybe we can come up with a drawing for what they had planned.

Edit: Ahh.. found several pics that show it having Nacelle mounted gear not fuse mounted. If that is what you were thinking I understand the confusion now and am on the same page. I'll be over in my corner being silent again.

 

[rockyboy]

Kinda why I sent you the entire A frame assembly so the stance is a tad wider.

That is a lot of prop below the water line hehe. What were they planning for landing gear on the originals? Stilts with wheels? According to wiki it used 3.8m 4 blade prop (12.6 foot dia) so the 1/10th scale we are working in puts a 12 in prop in the right ball park. also says it had retractable tricycle gear but no specs on those. I will look for more pics. maybe we can come up with a drawing for what they had planned.

Edit: Ahh.. found several pics that show it having Nacelle mounted gear not fuse mounted. If that is what you were thinking I understand the confusion now and am on the same page. I'll be over in my corner being silent again.

I didn't find any pics of a FW-42 plan with gear on the nacelle yet, but the FW-19 that it was loosely based on has retracts in the nacelles so that's what I had in my head. Fuse mounting would be simpler, but I'm worried about wings rocking on takeoff / landing.

 

[rockyboy]

Now that I've finished up this little beauty I can get it hanging from the ceiling instead of taunting me on the workbench...

Here's a thin plywood plate being gorilla glued to the center of the center wing section. This covers the entire area of fuselage contact, and will be fiberglassed on the bottom as well after I get the wiring holes and fuselage mounting bolts figured out.

I put the cutoff part of the wing box back on top so I had a level surface to put some weight on the glue joint.

How's this look for a landing gear idea? This is a throw away piece of music wire - you can see it sort of tied to the suspension plate with a little gardening wire for now - the next one will go through the holes in the suspension plate before I put the second bend in it.

The idea is to have it mount sort of like this under the nacelle spreading that vertical load out along the whole plate...

And then when I screw up the landing, the shocks compress and hopefully save me from my poor piloting!

The next wire I bend up will also be about an inch shorter on the long leg so the geometry prevents the wheels from folding back up over the shock at full compression. And I should be able to get clearance for a 14" to 16" prop still, but a 16 might mow the grass a little if I really slam it in.

So what's the wisdom of the crowds think here - am I completely nuts? This is my first crack at landing gear for a big plane like this, and I'm not going to shell out the dough for Robarts so it's going to need to be a DIY solution.

 

[PsyBorg]

I think if you use the top of the music wire as the hard mounted pivot point that will keep things from twisting. Then you would only have to angle the shock itself rearward a bit to account for the rearward travel when the shock is compressed. That dual wheel set up like that just looks tough. Those shocks can be set up to be nice n spongy or they can get tensioned pretty tight enough to probably bounce the plane back in the air as it has done to my truck before.

 

[rockyboy]

Yeah, the shocks are pretty neat! I like how the the tensioning design keeps the full length of the shock while ramping up the back pressure too. If I don't build too heavy I think it's going to work out! Thanks for the hardware brother!

 

[rockyboy]

Back from a work trip last week, and back to work. Gluing the bottom skin of the center wing in place. Nacelles getting roughed out too. Noticing that with the forward part of the nacelles it puts the engines almost exactly at the center of gravity for this beasty. Very handy.

 

[Grifflyer]

How's this look for a landing gear idea? This is a throw away piece of music wire - you can see it sort of tied to the suspension plate with a little gardening wire for now - the next one will go through the holes in the suspension plate before I put the second bend in it. View attachment 106848
The idea is to have it mount sort of like this under the nacelle spreading that vertical load out along the whole plate...
View attachment 106849

And then when I screw up the landing, the shocks compress and hopefully save me from my poor piloting! View attachment 106850

The next wire I bend up will also be about an inch shorter on the long leg so the geometry prevents the wheels from folding back up over the shock at full compression. And I should be able to get clearance for a 14" to 16" prop still, but a 16 might mow the grass a little if I really slam it in.

So what's the wisdom of the crowds think here - am I completely nuts? This is my first crack at landing gear for a big plane like this, and I'm not going to shell out the dough for Robarts so it's going to need to be a DIY solution.

Is that a shock + spring from an rc car?

 

[PsyBorg]

Is that a shock + spring from an rc car?

uh huh!!!

originals from my Franken truck.

 

[rockyboy]

Time to cut out the nacelle sides...

Getting better at this hot wire stuff.

Fits pretty good

Here I got things a little out of order. I cut off the curve at the back of the nacelle, but before I put the bottoms on. And with the landing gear being surface mount underneath the nacelle, I want the foam across the bottom to be an "A" fold arrangement with the sides. Oh well, it's only foam. Shouldn't be hard to correct.

Sharpened up a little piece of copper tubing and drilled wiring holes for the motors going into the nacelles, and aileron extension pass through to the outer wing panels.

 

[PsyBorg]

Think the FPV system is dead in the water for a bit mate. Had another batch of servos suicide on me... Will try better ones next round after I pay next months bills. 4.8 v should not be killing servos right? That's what I got feeding them from the pdb and what is at the end at the servos too. They work for a while then on a random power up they slam to one side and that is that. I been using them blue cheapies that were on sale I think I know why... Does the length of the signal wire have limits for distance? I will assume since I do not lose voltage over the length that the signal should not be degrading either for the same length. Don't have a working O scope to look at what that is doing so kinda have to guess here.

Gonna pick up the metal gear ones from FT which should be a lot smoother for the head tracking anyways. Hopefully they have better components in their electrical system.

 

[rockyboy]

That's whacky - 4.8 is standard voltage for servos. And I wouldn't expect any wire length issues on servo connections for way more than 10 feet. The giant scale folks do long servo runs like this all the time. I've had good experiences with both the PowerUp brand from http://www.headsuphobby.com/Servos-by-Brand_c_70.html and Emax brand that both Heads Up and Flite Test carry. Headsup frequently runs sales on them too

 

[localfiend]

Think the FPV system is dead in the water for a bit mate. Had another batch of servos suicide on me... Will try better ones next round after I pay next months bills. 4.8 v should not be killing servos right? That's what I got feeding them from the pdb and what is at the end at the servos too. They work for a while then on a random power up they slam to one side and that is that. I been using them blue cheapies that were on sale I think I know why... Does the length of the signal wire have limits for distance? I will assume since I do not lose voltage over the length that the signal should not be degrading either for the same length. Don't have a working O scope to look at what that is doing so kinda have to guess here.

Gonna pick up the metal gear ones from FT which should be a lot smoother for the head tracking anyways. Hopefully they have better components in their electrical system.

What kind of wiring are you using for power and signal? We had a horrible time last year at FF trying to finish a large build when servos and ESC's were going nuts. Stuff would work with short runs of wire, but long runs were completely unpredictable. We assumed that the cable we were using wasn't shielded well enough, and that the long distance made the signal far more susceptible to outside interference from power wires.

 

[DamoRC]

What kind of wiring are you using for power and signal? We had a horrible time last year at FF trying to finish a large build when servos and ESC's were going nuts. Stuff would work with short runs of wire, but long runs were completely unpredictable. We assumed that the cable we were using wasn't shielded well enough, and that the long distance made the signal far more susceptible to outside interference from power wires.

Yep - I have had the same problem (if the problem is servo signal interference), even over shortish runs. Twisted servo wire (or just twist the wire you have so that the ground wire runs around the signal) fixed this. Disclaimer, my issue wasn't actually with servos but with multiple ESCs on the C-130 build. When I triggered and aileron servo one of the ESCs would randomly re-set. Twisting the signal and ground wires to the ESCs solved it.

DamoRC

 

[PsyBorg]

The first two times I had it happen (luckily I was only working with two servos at that point) they were powered direct from the receiver once with an extension the second time without. That is why I went to thinner gauge wire for the longer run. the front two are powered on one 5v tap the other two are powered off the second 5v tap to make sure I am not pulling too much current over the runs. voltage at the tap is 4.8v and voltage at the servos are the same. If there is a drop its in millivolt or even microvolt range. the whole thing end to end is right around 6 feet so thast really not that far with the power distribution and signal coming from just off center of that whole distance.

I suppose I could pull the spare pairs of the ribbon and twist the existing wires or solder a pair of the extras to ground and wrap the ribbon. When I replace the servos again and see how long they go then.

BTW. when I am testing this it is all layed out on a long board flat , in line with nothing else near it to inject signals. I don't even use a wifi router or anything.

 

[Namactual]

I wonder if you guys could use Cat5 for the long runs. You could use one cable for multiple servos as well.

It might be worth a look.

 

[PsyBorg]

the way I have it now the 5v common to the two servos and the camera are on a single pair and the three signal wires are on their own wire. I have yet to power up the cameras yet as I wanted to get the head tracking finalized as well as the pivot point to make the view more realistic.

 

[Tench745]

Could be the signal wires running parallel to one another are inducing current (noise) in the remaining signal wires, driving the servos to an extreme. I would assume if this was the case they would swing to whichever side corresponded to a higher PWM signal. Or, it could be one of the signal wires is somehow getting an intermittent power surge from somewhere and when it does that induces a surge in all of them. Either way, try moving the signal wires apart from one another and apart from all the other wires as well while you're troubleshooting.

 

[localfiend]

Could be the signal wires running parallel to one another are inducing current (noise) in the remaining signal wires, driving the servos to an extreme. I would assume if this was the case they would swing to whichever side corresponded to a higher PWM signal. Or, it could be one of the signal wires is somehow getting an intermittent power surge from somewhere and when it does that induces a surge in all of them. Either way, try moving the signal wires apart from one another and apart from all the other wires as well while you're troubleshooting.

Yup, separate everything out. And don't try CAT5. That's what gave us all the trouble last year. Maybe things would have been fine if there was a ground wire inside the CAT5, but when it was used for just signal wires, bad things happened.

 

[PsyBorg]

You guys think if I keep the ribbon in tact that I can do Signal, Ground, Video, Positive, Signal and have enough separation? I am not doing the aircraft build. This is for Rockboys FW 42 and I don't wanna stick him with spaghetti lab if I can help it by having separate wires to run the entire length of the fuse with bomb bays and cock pits and flight electronics as well.

He is putting flight electronics up high so I was shooting for a single wire run down the bottom with taps leading up to the main power and video control electronics.

 

[Tench745]

You guys think if I keep the ribbon in tact that I can do Signal, Ground, Video, Positive, Signal and have enough separation?

Dunno. Without an oscilloscope I think the only way to find out is to try it.