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Cessna 152, Balsa 30% Scale Rescue from Hostetler Plans

Joker 53150

Mmmmmmm, balsa.
Mentor
#1
Yes, another plane. What are you, my wife with the questions and yelling? :p So a few weeks ago I went to a swap meet near Green Bay, and was bidding on this plane which was being auctioned off as part of an estate sale. I gave up and let another guy win, and it turns out he only wanted the gas engine it had, while I (mostly) wanted the airframe.

I asked him to let me know if he decides to sell the airframe, and a few days ago he gave me a price. We met at another swap meet this morning and now she's mine!

The plane is a scratch-built Cessna 152 from Hostetler plans, at 30% scale. That gives it a 120" wingspan which is the largest in my fleet. It needs an engine, so for now I'll swap in the 58cc gasser I got for my Hostetler L-19 Bird Dog. It's a little rough in spots, but is good enough to fly this season. It does need a couple flap servos, some minor repair work to one of the wing struts (not pictured here), and some shrinking of the covering. The interior is very basic and will benefit in the future from some detail work. But for now it'll simply be made "flyable".

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#2
Thats awesome! What a beast. I almost bought a huge Cessna at FFeast last year. It was only like $90. I would like to get some big balsa planes in the near future, along with a gas or nitro engine.. The biggest plane Ive flown is a 60" foamboard Skymaster. Anyways, I wouldn't mind seeing the rebuild process so keep us updated.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#4
Can't wait to try and get it down the stairs to my shop! :) I've got to finish up a couple other planes first though... First up is finishing the canopy for my Winter Build-Along Extra 300, then there's a 4-stroke glow P-51, and last sticking an engine in my buddy's 1/4 scale Cub. That'll give me a little time to review the Cessna in more detail to see what it really needs to get it in the air.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#5
A couple things balsa builders will agree on is that Hostetler plans are very well drawn and that they leave a lot of the final build decisions to the imagination and skill of the builder. Some details are omitted from the plans because "the builder should know what to do" or because there isn't enough space on the plans to list all details. I noticed this with the L-19 I'm building from his plans - details like how thick the door will be or how they're constructed aren't answered. In the case of this Cessna the builder made the entire door the same thickness as the fuselage sides. For this plane (and in the L-19) the fuselage is made from an inner box-structure and then planked to create the final shape. That means the fuselage is about 1" thick in most areas! Not solid, but from inner box to outer shell.

When the doors are opened they're super thick and chunky looking, which includes the upper structure around the window. One of the doors is hinged and the other side's hinges have torn out, so some door work is required before the plane can fly. In the long run both doors will be completely re-built as both doors have a lot of hangar rash and I want to make the upper portion much thinner. Here's the door that needs work before it can fly. It's usable, but the handle is missing, hinges are shot, etc. It's not an illusion, the lines of the covering are a bit wavy! :p

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From the inside you get a better idea how thick the door is, especially at the top. While I'm not planning to go crazy with scale details I'll eventually fix this so it looks a bit closer to the real thing. The entire door could be re-built thinner which would give me more interior room, although space in a plane this size really isn't a big problem! :)

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Joker 53150

Mmmmmmm, balsa.
Mentor
#6
Well this is interesting.

Since I'm between projects waiting for parts I took one of the wings to my shop to see what it's going to need for repairs. When I looked inside I saw a bunch of wires which turned out to also include a strobe light controller! I did know that the wings included navigation LEDs, but didn't notice the strobes at each wingtip, a nice little surprise.

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Here are the strobe and nav light in action. You can also get a look at the covering - functional, but not the prettiest. That strobing light is MUCH brighter in person!



This is the mass of wiring inside one wing. Connections are twisted, soldered, and taped with electrical tape. Part of the rehab work I'll do will include fixing this up a bit.

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#7
That's a giant plane! What's the AUW going to be? Will it fly scale, or will it be fast?

I'm not sure I could leave that covering alone. It's just scruffy enough that I'd probably strip it. Or, maybe it will shrink up with a little heat from the iron or heat gun. The rough edges in the door openings and on the doors would drive me batty, but I'm funny about that kind of thing.

I probably couldn't pass up that plane either! Even if I don't have an engine for it. I like big planes.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#8
I really want to strip and recover it, but am resisting the urge the best I can as that will add a lot of time and expense. I did shrink one wing a bit which helps, but it’s still ugly.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#9
Oh, and the final weight will probably be around 25 pounds. It's currently got about a pound of metal plating bolted to the firewall for nose-weight, and my hope is that it comes in under 25. The statement from a friend of the builder is that flaps weren't needed as it flew slow enough without them, but I'm having a hard time picturing 25 pounds of plane flying that slowly. :confused:

The flap design is pretty slick, and I'll post some pics or video on how they work soon. Probably when I start building the missing servo mounting plates.
 
#10
10’ is a lot of wing! I am always amazed at how a big plane flies. I have to imagine the Hoerner tips make a difference too, for the slow flight characteristics. Have you figured out what the cube loading is? The wing loading will say a lot about how it will fly.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#11
I haven't looked at wing loading or done the math. The areas I fly have a ton of room so if it comes in a little hot there is still plenty of distance to land safely. I put a 1/4 scale Cub fuselage next to the Cessna yesterday which makes the big Cub look small! :)
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#12
Time recently has been limited, but I did a little work on the Cessna wings. First up was trying to sort out the rats-nest of wiring. The servo extensions were fine, but the LED and strobe lights were spliced somewhat poorly and the plugs at the ends were covered with glue, bent, etc. When I powered up the strobes I could hear "snapping" from the current at the plugs, so I figured there were bad connections. All connections were re-built with new plugs and wire and testing afterward shows the problem is fixed and operating properly.

Turning to the LEDs... the red operates properly but the green is dead. To make it more fun, these are big-honkin' LEDs, 10mm across. I found a source for replacements and they're fairly cheap. Assuming it flies well and is a "keeper" I would upgrade the lighting system anyway, so spending money on it now may not make much sense. I'll probably just get the green LED anyway since it's cheap - it'll help distract people from the shabby covering job! :)
 
#13
Just pretend it’s one of those sad little 150s that has spent its life sitting outside, roasting in the sun.... they usually look pretty tattered. There’s a 172 at the Idaho Falls airport that sits outside and only gets flown about once a year. I’ve seen it with flat tires. One of my guys that works for me says he doubts the pilot or plane are likely current, but he flies it anyway, once a year whether it needs it or not :black_eyed: It was a nice plan once. It’s got hoerner tips and a few other little upgrades. But, it’s been outside and seemingly neglected for 20+ years. So your 150 is a scale model of one of those derelict tarmac queens.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#14
Starboard wing repairs are started. First up, I did end up ordering new navigation lights. $5/ea for 10mm red and green with extended wires so I won't have to splice them to reach, and even with the custom length wires I should take delivery by Tuesday. It was simply going to bug me that the lights weren't both working...

When I got the plane I was told that one of the wing strut bolts needed repair. Turns out the fix was pretty quick & easy! The way it's designed is also fairly simple - a hardwood block is built into the wing and a threaded insert is screwed into it. The strut bolt then screws into this insert. On this wing the threaded insert was pulled out which meant the hardwood needed repair so it would hold firmly again.

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I have various size hardwood dowels, so I picked one that was oversized and drilled a hole in the wing for it. At the same time I also added some balsa to bring the surrounding area up flush with the rest of the wing. For some reason the hardwood was recessed on this wing, but not the other one.

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After the glue set for a day I came back and drilled a new hole for the threaded insert.

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A little filler and light sanding completes the bulk of the repairs. In removing the old covering I wasn't too gentle - this is more of a MASH-type repair to get the wing put back together and stable, eventually it will be gone over in detail to make it pretty.

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A new patch is applied, finishing this small repair.

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The wing struts will eventually be replaced with something a little less "chunky", and more accurate to the original Cessna design. But for now, they're functional.

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Moving over to the flap servo on the starboard wing, or should I say the "lack of flap servo"... The entire servo tray is missing from each wing, so the first step was making a new hatch. Notice the multiple pieces of covering, uneven gaps around a square hatch, etc? Since this all isn't getting repaired NOW it's why I didn't bother making a super-neat patch around the wing strut bolt repair. Most of this is just cosmetic and simply re-covering the wing would do wonders for the appearance, but that's time and money I don't want to spend on it right now.

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Inside the flap servo hatch is the pushrod for the hidden control. I peeled back more covering than planned as I found some structural issues that need to be addressed. Nothing major, but peeling back the covering allowed me to better see the area requiring work.

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I like the flap design (although the actual construction and covering leave something to be desired). Notice there is no visible pushrod or control horn - that's all inside the wing.

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The pushrod pushes the entire flap surface back, and the hinge style then angles it downward. Fowler flaps, is what I believe they're called. When the wings are re-built I have plans for some scale detail changes to the control surfaces that I'm looking forward to trying, but that'll have to wait.

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Joker 53150

Mmmmmmm, balsa.
Mentor
#15
Just pretend it’s one of those sad little 150s that has spent its life sitting outside, roasting in the sun.... they usually look pretty tattered. There’s a 172 at the Idaho Falls airport that sits outside and only gets flown about once a year. I’ve seen it with flat tires. One of my guys that works for me says he doubts the pilot or plane are likely current, but he flies it anyway, once a year whether it needs it or not :black_eyed: It was a nice plan once. It’s got hoerner tips and a few other little upgrades. But, it’s been outside and seemingly neglected for 20+ years. So your 150 is a scale model of one of those derelict tarmac queens.
I see the occasional plane like that as well, just rotting in the open - very sad. :(
 

AkimboGlueGuns

Biplane Guy
Mentor
#16
Just pretend it’s one of those sad little 150s that has spent its life sitting outside, roasting in the sun.... they usually look pretty tattered. There’s a 172 at the Idaho Falls airport that sits outside and only gets flown about once a year. I’ve seen it with flat tires. One of my guys that works for me says he doubts the pilot or plane are likely current, but he flies it anyway, once a year whether it needs it or not It was a nice plan once. It’s got hoerner tips and a few other little upgrades. But, it’s been outside and seemingly neglected for 20+ years. So your 150 is a scale model of one of those derelict tarmac queens.
I see the occasional plane like that as well, just rotting in the open - very sad.
I know exactly what you mean. Up in Fond du Lac there's a 172 fastback that sat on the ramp for about a year and a half, getting literally rusty. Eventually the owner towed it away and had it scrapped. Sad to see it go like that.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#17
Both wings are pretty much done (for now), other than adding the navigation lights which I should have in a few days. That means it's time to get started on the fuselage! :) The big concern I had was actually getting it through the house and down the stairs to my shop, but with my wife helping guide it we got it there in one piece. For a size comparison here are a couple shots with my friend's Sig 1/4 scale Cub. The Cessna is 30% size and almost a foot longer.

All servos in the fuselage were tested and no problems were found. Like the rest of the plane there will be some tweaks made now followed by bigger changes later on.

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For the pushrod connection at the rudder I'm not sure what is going on. My assumption is that the pushrod was a little too short and instead of replacing it a plate was added to the control horn. For a plane this size my preference would be a pull-pull system, which is what it'll eventually get. Note the silky-smooth covering... :rolleyes: Hopefully this can be made a little better with some shrinking. The wings are still rough, but look much better since spending time under the heat gun.

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Joker 53150

Mmmmmmm, balsa.
Mentor
#19
Time to start prepping the firewall for the new engine, a 58cc gasser. After removing the cowl I'm greeted with big chunks of lead stuck to the firewall. Hopefully I'll be able to remove some of this once the new engine is installed! Another thing I noticed quickly is that the firewall was never sealed as is typical with liquid-fueled engines. It's got some discoloration/staining from exhaust on it, but it's not too bad overall.

I'm also plugging the original mounting holes to clean up the firewall. As with the rest of the covering, the extra material hidden under the cowl was a bit rough.

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Fast-forward a bit and the firewall is about 2/3 done. Holes are plugged, extra covering is trimmed and sanded back, the firewall has been sanded to remove much of the staining, and a layer of epoxy has been applied to seal it. I wanted to do it all in one shot, but when all of the weights are removed the tail drops. This plane is so big and the tail is hanging WAY off my bench so that could be a problem, so I just decided to do the work in two phases.

The engine will need 2cm standoffs to get it the correct distance from the firewall, and luckily enough I happen to have 2cm standoffs in my stash-of-stuff! :)

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