Cessna 152, Balsa 30% Scale Rescue from Hostetler Plans

[Joker 53150]

Well, no flying this weekend for the Cessna. I took it out to the sod farm/flying field to at least get some taxi-testing with it and ran into a couple problems. First, when it's running the servos are getting some interference and the tail surfaces are moving quite a bit as the throttle changes. Probably not the safest way to fly...! Next, the engine needs a little tuning. It fires up and idles well, but as I add throttle it cuts out a bit. Oh well, the engine is still new and should be broken in a bit more before trusting it to fly. Soon... soon...

 

[Joker 53150]

A couple updates on the Cessna...

First, I'm able to get a little more done on it as my son's cancer treatments are working better and faster than I would have hoped for. He's still got a number of chemo treatments to go, but the treatments aren't hitting him nearly as bad as they do some people. He's run down for a couple days while getting chemo, and within a day is back to "normal" and feeling fine. Since he's hanging out with friends that frees me up to play with my toys!

Second update, I'm changing the electronics quite a bit. The phantom jitters experienced during the test-runs has me spooked so I'm trying to re-organize how it's wired. Although the two servos were working together and they gave me redundancy I decided to pull the plug on them and go with a power distribution box. I found one I like from Red Wing. It still gives me two battery inputs, 6 volts to the servos and regulated 5 volts to the receiver. It also has an alarm LED and beeper plus isolated voltage for the CDI box. The down-side is that I won't have as much programming flexibility as when I was running 16 channels, but on the good side I'm not powering a bunch of big servos through the receivers.

So far I've got channels 1 (throttle), 3 (elevators), 4 (rudder/steering), and 8 (throttle Opti-Kill) hooked up. The two elevators need some tweaking so they're even, which was very easy to do through programming when they were on different channels. I'm really hoping that the ailerons can be adjusted properly so they can share channel 2, but am pretty sure the flaps are going to need to be on different channels. The steering servo may also need it's own channel as it's got a ton of throw compared to the rudder. Neither can easily be adjusted manually to change that, so programming may be the best route. Another hour or so tweaking it and it should be ready for a run test, and hopefully the jitters will be gone!

 

[rockyboy]

This is lots of awesome news rolled into one update Jeff!

 

[Joker 53150]

The new power distribution box has the plane about ready to test-run again, and I'm looking forward to seeing if the jitters go away. If not I'll have to do some more trial & error to track it down. The servo extensions for the ailerons and flaps are going to be left unplugged until after I test it with channels 1, 3, and 4 only hooked up, and if it works properly I'll add the extra servos and wiring step by step to make sure it remains good.

I also found that this new power distribution box has a built-in optical kill for the electronic ignition. If I use it (and I am), it uses one channel on the receiver. However, I'd need to use that channel to run the external opti-kill anyway so I'm not losing anything except an extra piece of hardware. The box has a built-in light to show power is being sent to the ignition, and it isolates a separate battery dedicated to the ignition as well. I could also simply jump from one of the servos to the ignition battery input and use the same batteries for the ignition that I use for the servos, but I'd rather keep the ignition on it's own battery. So I'll run two batteries for the servos and receiver - both of them run through my power switch panel with redundant switches and then into the power distribution box which will also run just fine if one of the batteries dies. The ignition battery is also still run through my switch panel before being connected to the distribution box. It sounds confusing, and it kind of is... But I like what it does to clean everything up, and if it works as it should I'll add this kind of box to future giant-scale builds. Right now this one is simply added to the plane, but with some planning during the build it could be built-in and look much cleaner.

 

[Joker 53150]

Not a huge update, but I finally fired up the Cessna with the new power distribution board installed and the servo twitching has gotten better, but has not been eliminated. A common area of concern would be the electronic ignition module, but in my case it's mounted in front of the firewall and far away from the rest of the electronics. It COULD still be causing interference so I'm going to swap it out with the module from the other 58cc Turnigy gas engine I've got for my L-19 project to see if the problem goes away. I'm also going to re-check to make sure all servo connections are tight. If neither of those help I've got another more involved thought or two that I'll look into. Either way, with the improved operation I did notice that the engine was running better/smoother, probably because the twitching was also hitting the throttle servo as well as the tail servos. In fact, it was running well enough that I took the plane for a "walk" around the yard. That 58cc gasser really has no problem pulling this heavy bird through grass!

 

[PsyBorg]

Would a filter cap or two strategically placed in the power system help better that twitchy servo issue like they do on high power quads.

I remember that noise in the radios years back from engine ignition. A simple capacitor cleared that all up and became a standard part of the cars since.

 

[Joker 53150]

Remember this beast? It's FINALLY back on the workbench so I can get the electronics sorted out. It's been sadly sitting in my garage for the last 18 months or so and I hated seeing it collecting dust, but for a while now I had no way to even get it to the field. But now I finally have a vehicle big enough to carry it... For those not familiar, note the 12 ounce soda can in the foreground for size reference. The engine is a 58cc Turnigy gas engine.

The last time I worked on it I was trying to sort out some electrical noise problems. I've learned a lot since then and have some new thoughts on how to proceed. First, I used a couple extensions for the ignition module power. These will be replaced with a single twisted line connected to a better ignition kill module than I had previously used. A few other servo extensions will be replaced with heavier gauge twisted extensions. I'm not sure if I'll use the big power distribution board shown in a previous post or not. I may go with the same smaller power distribution module on some of my newer planes and at the same time get rid of most of the power switches I used.

First up will be stripping out some of the excess wiring so I can finalize a plan. I want this bird flying in Spring!

 

[Joker 53150]

As just mentioned, I'm going with a better quality optical kill switch for this plane than I started with. As with a couple other recent builds, this one will be getting an Ultra IBEC by Tech-Aero Designs. This switch is supposed to be better at filtering noise from the ignition module than other opti-kill switches. It's also got a built-in voltage regulator so I can pick what voltage the ignition module receives. Like other switches, it's also got an LED to let me know the ignition is live or not.

For power distribution I'm still weighing my options, but I may go with a VR Pro Dualsky setup again. It's much smaller than the big power distribution board I was planning to use, and it's a simpler design. I ordered one now since it'll take a couple weeks to get here, and if it doesn't go on this plane it'll be used on another one soon enough.

Also something that needs to be looked at (again?) is the fuel tank. I'm pretty sure I rebuilt it when I started doing all the work on this plane originally, but have no pictures to back that thought up. If it was rebuilt, it should (hopefully?) have the good flexible tubing inside for the clunk. The regular Tygon tube gets hard over time which makes it less effective. The plan is to pull the existing tank out to see if it's been rebuilt or not, and to possibly switch to a Fiji bottle with an aluminum cap. With all this stuff, I don't want to go back and have to do all the work again...!

 

[OliverW]

As just mentioned, I'm going with a better quality optical kill switch for this plane than I started with. As with a couple other recent builds, this one will be getting an Ultra IBEC by Tech-Aero Designs. This switch is supposed to be better at filtering noise from the ignition module than other opti-kill switches. It's also got a built-in voltage regulator so I can pick what voltage the ignition module receives. Like other switches, it's also got an LED to let me know the ignition is live or not.

View attachment 157956


For power distribution I'm still weighing my options, but I may go with a VR Pro Dualsky setup again. It's much smaller than the big power distribution board I was planning to use, and it's a simpler design. I ordered one now since it'll take a couple weeks to get here, and if it doesn't go on this plane it'll be used on another one soon enough.

View attachment 157957


Also something that needs to be looked at (again?) is the fuel tank. I'm pretty sure I rebuilt it when I started doing all the work on this plane originally, but have no pictures to back that thought up. If it was rebuilt, it should (hopefully?) have the good flexible tubing inside for the clunk. The regular Tygon tube gets hard over time which makes it less effective. The plan is to pull the existing tank out to see if it's been rebuilt or not, and to possibly switch to a Fiji bottle with an aluminum cap. With all this stuff, I don't want to go back and have to do all the work again...!

Awesome! Keep major watch of the wing joiners. My dads failed on his hostetler skymaster..

 

[Joker 53150]

Ouch! The Skymaster must have made quite a crater.

 

[Joker 53150]

Fuel tank follow up. I DID rebuild the tank when I started working on this plane, and went with a dual clunk setup with Tygon fuel tube. I’m going to redo the entire system using a Fiji bottle and aluminum cap, with a standard 2 line setup. The Fiji bottle is narrower, longer, fits better, and is clear. It’s also the same volume as the stock tank. Wins across the board!

 

[Joker 53150]

The interior of the fuselage is gutted of extra wires and I'm able to start work on the new layout. Previously, the big gas tank was centered on the platform shown below. That was nice for lateral balance, but made it hard to fit other components next to it. The plan is to move the new Fiji gas tank to the left side of the fuselage which will free up room for the flight batteries.

I'm also planning now to use the power distribution panel that was planned for a while back. I'll plug all servos into it (including the ignition kill switch) except for the flaps. Flaps will be run off an SBUS to PWM/PPM decoder plugged into the receiver. This will let me plug each servo into it's own channel without using a "Y" harness. The way the plane was built it would otherwise need servo reversers, and this will just cut down on the amount of "stuff" inside the plane. I haven't worked with an SBUS decoder in the past, but it looks fairly straight-forward. In this case I'll only be running two servos from it, so power demand should be fairly minimal, and the flap servos would be the only servos getting powered thru the receiver (the rest get power from the distribution board). Power will come from two 3300mAh 2 cell LiPo batteries.

For those not familiar with how stupid-big this plane is, here's my Willy Nillies J3 Cub chillin' inside it, with plenty of room to spare.

 

[nhk750]

Awesome! Keep major watch of the wing joiners. My dads failed on his hostetler skymaster.. View attachment 158000

Wow, a real disaster, impressive debris field.

 

[nhk750]

The interior of the fuselage is gutted of extra wires and I'm able to start work on the new layout. Previously, the big gas tank was centered on the platform shown below. That was nice for lateral balance, but made it hard to fit other components next to it. The plan is to move the new Fiji gas tank to the left side of the fuselage which will free up room for the flight batteries.

I'm also planning now to use the power distribution panel that was planned for a while back. I'll plug all servos into it (including the ignition kill switch) except for the flaps. Flaps will be run off an SBUS to PWM/PPM decoder plugged into the receiver. This will let me plug each servo into it's own channel without using a "Y" harness. The way the plane was built it would otherwise need servo reversers, and this will just cut down on the amount of "stuff" inside the plane. I haven't worked with an SBUS decoder in the past, but it looks fairly straight-forward. In this case I'll only be running two servos from it, so power demand should be fairly minimal, and the flap servos would be the only servos getting powered thru the receiver (the rest get power from the distribution board). Power will come from two 3300mAh 2 cell LiPo batteries.

View attachment 158057


For those not familiar with how stupid-big this plane is, here's my Willy Nillies J3 Cub chillin' inside it, with plenty of room to spare.

View attachment 158058

That is really cool!

 

[OliverW]

Wow, a real disaster, impressive debris field.

Agreed! He was trying to have me fly it a couple if minutes before the wings folded

 

[Joker 53150]

Agreed! He was trying to have me fly it a couple if minutes before the wings folded

The spars are pretty impressive on this bird. As long as a wing doesn’t come off and if I avoid 3D flight I should be good!

 

[OliverW]

The spars are pretty impressive on this bird. As long as a wing doesn’t come off and if I avoid 3D flight I should be good!

We felt the same, and it gave way in a big slow turn. It is just something to keep an extra close eye on. My dad opted out for hostetler's wing joiners on his 126" decathlon

 

[Joker 53150]

We felt the same, and it gave way in a big slow turn. It is just something to keep an extra close eye on. My dad opted out for hostetler's wing joiners on his 126" decathlon

Here's hoping this one was built to handle it. It has flown, but no idea how many times. From what I've been able to determine so far the spars are solid, and the wing struts are way over-built. To be safe I'll do some extra inspection inside the wings.

How'd your dad change the design for the Decathlon? I'm building Hostetler's L-19 and haven't started the wing yet. It's designed like this Cessna's spars.

 

[Joker 53150]

Part of my re-do on the electrical wiring on this plane involves removing all of the switches I had hidden inside the "baggage door". These were to to control power to two batteries, the ignition, and the light circuits. Each circuit had two switches for redundancy, which meant a lot of switches and about 15' of power wire total. That could have been the cause of the electrical noise I was getting when the engine was running, or it could have been the plethora of servo wire extensions. Either way, I'm changing both of those. The power switches are replaced with a single "master switch". The switch is a "fail safe" design that won't kill power to the distribution board if the switch fails. It also gives me a voltage read-out, which is nice. I'll add a picture of all the wiring I've removed so far, which doesn't include all of the misc. short servo extensions.

Speaking of extensions, I decided to quit buying extensions and build my own. I've done it a few times in the past and it's fairly easy. This will save money and let me make extensions to fit the need, and not simply buy "close enough" sizes. I ordered twisted 22awg wires for the project.

 

[OliverW]

Here's hoping this one was built to handle it. It has flown, but no idea how many times. From what I've been able to determine so far the spars are solid, and the wing struts are way over-built. To be safe I'll do some extra inspection inside the wings.

How'd your dad change the design for the Decathlon? I'm building Hostetler's L-19 and haven't started the wing yet. It's designed like this Cessna's spars.

He put carbon fibre tubes in the wings.