Rudder Fin & Fuselage

IMG_7411

This is the fin structure. The fin is the stationary part of the whole rudder, the rudder is the part that moves left and right to steer the whole plane. The fin here is basically just a triangle. This is made out of wood and glued together, and i’ll mount the hinges and rudder horn and support to it, and then cover it with plywood and paint it and coat it. I also welded together some of the fuselage frame. I don’t currently have a picture of it, but its made of three quarter inch steel tubing, and currently I’ve welded the front section of the fuselage, (most of it), and then i’ll finish the tail section. The frame is strong but fairly light, and then i’ll bolt ribs of wood to it and then plywood will cover the ribs.

First engine casting!

Well finally, i’ve made a successful casting of the engine piston! Seven more to go.

IMG_7362[1] IMG_7363[1]

So it looks a bit rough and weird as is, but next up is a bit of lathe work, and i’ll be doing what i described in the previous post. Plus, i’ll polish the surfaces and buff them to make it flat and neat. This process repeats 7 times, and i have all the pistons in my engine. And the pistons are one of the major parts, besides the crankshaft and engine block / cylinder heads, this requires most material for a single part. So when i finish all the pistons, next on the menu is an engine block. Like flat engines and boxer engines, it’ll be a two part block, so two halfs you bolt together. That’s much better for me because i’m using expensive molding sand for casting. When i’m done with the block i’ll go on to the crankshaft, made from steel. But lets not get ahead of ourselves, we have some pistons to make. A few words on the engine block, i’ll need a lot more than just aluminum cans to gather material for it, and i’ll need a bigger furnace. I think i’ll need to buy some aluminum, or if i find enough scrap aluminum. I’ll make the main sand mold from the usual molding sand i bought, mixed with special oil. The sand cores, which make up the inside cavities of the block, will be made by using that same sand and mixing sodium silicate, and then harden it using CO2 gas. I still need to figure out how to make the larger furnace. i haven’t quite gotten to that part. But my next job is to machine the piston into its final shape, and then make 7 more.

The Pistons Part One

How are pistons made?

Well it’s time to start working on the pistons. The pistons will be made out of aluminum which is a good material choice for pistons, because it’s lightweight which is especially good for aircrafts, and aluminum is very thermally conductive, so it cools down fairly quickly. And the block is also made of aluminum so the heat will spread into the block. The other material choice would be steel, which is used in many, if not most cars. aluminum pistons are rising in popularity though, you might find them in new cars. Cast iron pistons are heavy though, which can be a problem for aircrafts, because they need to be as light as possible.

There are three common types of piston manufacturing method. The first method is forging, which involves either a hammer or a press, at a very intense pressure, and it drops a “forging die” onto a chunk of iron/aluminum, pressing it into shape. Forged pistons are very strong, but heavier due to compressed material. The second option is casting, which as you probably know is pouring the molten metal into a mold. In these two methods usually you would machine them further to get them into the final shape. The third method which is not very common would be simply machining the whole piston out of a block of metal, using CNC machining and lathe working. I use the second one, casting. The reason for that is because cast aluminum is very light, lighter than if you were to forge them. Another reason is that its a lot less costly for me, i already have an aluminum foundry, however getting the tools required for forging is not very easy, because you would need a huge drop hammer or press requiring up to thousands of tons of pressure. Obviously that’s very expensive equipment. And i don’t have a CNC mill so i cant use the third option, so for me the simplest option is casting.

After casting the pistons, i will move the pistons over to a lathe. My mold will be slightly larger than the final product, both due to heat expansion of the metal (which is more of a problem when you cast iron, if i’m correct) and because the casting will never be a perfect cylinder shape. I’ll simply take the cast piston, and use a lathe to machine it down to the correct diameter, which in my case is about 88.5 millimeters, 1.5 millimeters under the cylinder bore. That’s simply so that i can fit the piston rings. After i’ve done that i’ll make the groves for the piston rings. This is done on a lathe as well. After that the only thing left for me to do is to drill the hole for the wrist pin. I could simply cast the hole but that adds complexity and the hole would never be perfect so i’m better off simply drilling it manually. The last thing i do which is optional because its not on all pistons, is to drill holes from the oil ring grove and into the piston’s cavity, this is the return path of the oil.

And that pretty much sums it up, so lets get started shall we!

First thing i did was make a wooden model of the piston, slightly larger than the final product and i explained why in the text above. Here is a picture of it:

IMG_5494[1]

This is the wooden model i’ve made of the piston. I just need to file it ever so slightly so it’s perfectly symmetrical. The red marker lines you see is just what i used to measure out where to cut. Below is an image of the very much unfinished piston cavity:

IMG_5499[1]

 

The picture is slightly blurry, but what you may notice is that the bottom of it is not flat like i want it to be. This is a problem for me because i cant use my router, it doesn’t go deep enough into the piston. But the solution i’ve come up with is to buy these polishing stones you can buy in a hardware stores. You can put them in a hand drill, and use them to polish surfaces, and its a very handy thing to have.That should take care of my problem quite nicely. After i’ve done that it’s off to the foundry with it. I need to make 8 of these. I cant cast it just yet because i don’t have any molding sand at the moment, but i’ll buy some fairly soon so i should be able to get going with these babies!

Aluminum Casting

Well, i got my mini foundry going, and i successfully cast aluminum from cans. Though it didn’t quite take shape of the mold, i believe this is because the aluminum wasn’t hot enough to stay molten. However i got a big fat ingot of aluminum, which i am very proud of!

 

IMG_5283

Aluminum Ingot

This solid block of aluminum used to be soda cans (And a little bit of aluminum foil to get the melt started). I can melt it again when i need to use it. The good thing about melting cans into ingots, is that when i melt it again i don’t have to deal with as much slag, the caster’s worst enemy. There’s always gonna be a little slag, but not too much. I forgot to take a picture of my furnace in action, but i’ll do it the next time i melt aluminum. The furnace was hot enough, and actually too hot. I used a tin can for food as a crucible, which are usually made from iron (Despite the fact that they’re called tin cans). I use charcoal and air to fire it, and when i run it on full blow the crucible gets red hot very quickly. In fact if i run it on full blow for too long, the bottom of the tin can basically exploded and molten iron splattered inside my furnace. Not very nice. So i just got another can and tried keeping the heat down, and a few tin cans later, i was able to maintain good heat by turning on the blow until it got red hot and then turning it off again. I just have to be very careful. I might make a better multi-use crucible later. Anyway, i wasn’t able to cast the gear, so i need to look into what went wrong.

Timing Gear

The timing gear might seem like an unusual place to start in building a piston engine, but the reason for this is that it is fairly simple to cast. I cast it using aluminum, and i made a model out of wood which is shown below.

Timing Gear Model

Timing Gear Model

Here i have made a model of the timing gear using wood. I began by making a drawing of it on the computer, by using Inkscape’s useful render gear tool. The smaller one mounts onto the crankshaft, and the larger one is for the camshaft. The smaller one is half the size of the larger one, so when the larger one rotates one circle, the smaller one goes two. Now what i need to do is to make a sand mold of these, and cast aluminum 🙂

The Engine

Engine Intro

The engine i intend to make will be a Flat-8 piston engine which drives a propeller. I make it entirely out of scratch, and the design is made by me. Flat piston engines are good for airplanes due to their balanced weight and low center of gravity. Most parts of the engine are made by casting, and most of them are aluminum. I try to make all the large parts out of aluminum, including the engine blocks, pistons, engine heads, and timing gear to name a few. Aluminum is also a nice material to work with and cast. It will run on gasoline, and i have made a few initial calculations.

Some technical data:

  • Configuration: Flat-8
  • Firing order: 1-6-7-4-8-3-2-5 (Each 90° of crankshaft rotation one piston fires)
  • Cylinder bore: 90.0mm or 3.54in
  • Piston stroke: 82.5mm or 3.24in
  • Engine displacement: 4200 cc
Crankshaft Drawing

Crankshaft Drawing

Here is a drawing of the crankshaft. I consider the crankshaft to be the heart of a piston engine.

 

Firing Order Sketch

Firing Order Sketch

And just for show, this is a sketch i made when i was designing the firing order. The quality is not so good, but i made a table of arrows, each indicating the location of the crank for each piston. This shows the location of each piston in respect to a time unit i call t, each is a quarter of a turn of the crankshaft, so 8t is two turns of the crankshaft which is a full cycle for a four-stroke engine. A dot next to an arrow means it ignites the respective cylinder.

Introduction

Hello, and welcome to my blog! On this blog i will be sharing with you how i will hopefully manage to create an airplane entirely from ground up. I’ve been interested in cars and engines and airplanes for a while now, so i decided to start with the big project, of actually building an airplane. Now a couple of people have successfully made a home built airplane, but most of them do not bother making an engine. I however am creating the engine from scratch. The airplane will be a four passenger one, kind of like the set up of a car. It will be a steel frame, and the main material will be wood, and maybe covered in some sort of protective carbon fiber plastic layer, and then painted to look nice. Wood was used in early aircrafts, and is now used in home built aircrafts due to its low price compared to aluminum alloys. Anyway, i do hope that you will enjoy my blog, and you can read my upcoming posts. I’ll start by building the engine.