Echo 16CC IC engine conversion to model airplane engine

[Twmaster]

My other expensive hobby is flying R/C airplanes and crashing R/C helicopters.

As my vision is deteriorating I cannot see well enough to fly the smallish planes I've been flying for years. So now I am looking at bigger planes. Up until this I've flown nothing but electric powered craft for the last 10 years or so. Nitro-methane fuel is silly expensive at between $20 and $30 per gallon so that is out of the question for me. Flying larger electric planes is also very expensive.

So in steps the small 2 stroke power equipment engine....

I bought two of these little Echo gas string trimmers. One runs, one has a bad bore/piston. I'm using the bad engine as the guinea pig.

First step is to get the engine relatively bare of the housings and such.

The following photos are the 'before' shots.

Weight as shown is just a hair over two pounds. I'll be doing away with the flywheel/magneto ignition and instead be using an electronic CDI type ignition.

This engine should be able to spin an 18 inch prop and fly a 9-10 pound sport airplane.

More pics of the work as it goes along. I hope to have a couple of posts per week until complete.

Thanks for looking!

 

[zeeprogrammer]

Neat! I'll be watching.

 

[agmachado]

I too !

Let us know more details of your project...

;D

Take care,

Alexandre

 

[Twmaster]

A little more work this evening. I disassembled the engine so I can machine the front half of the crankcase housing.

Here is the part ready to be milled:

The part as shown is 7.55 ounces. I'm really anxious to see how much it weighs after it's surgery.

It got too cold in the workshop for me to keep at it tonight.

 

[Deanofid]

Glad to see something from your shop, Mike. : ) I'll be watching too.
This should bring back some memories. Years ago I worked for a gubment contractor. We made 1/4 and 1/5 scale target drones that used Quadra and Harris two stroke engines. I spent many hours milling off all the extra castings and turning the front bearing bosses for ignition modules. They got sent up, and often came down in pieces, kind of like RC planes, (sometimes!).

 

[metalmad]

this post will a very interesting one to watch
will be following along
cheers Pete

 

[Twmaster]

Thanks for looking in fellahs!

I managed to get some shop time this evening. I got the front crankcase mounted on the rotary table. I had to make some bits to hold it centered on the R/T. Thankfully I got another lathe today so finally I have a working lathe to make parts like the bushings to hold this.

Anyhow... All the trimming is done. The first of these three photos shows the part after I sawed off the top of the bellhousing and mounted/centered the thing to the R/T. Next photo is in the vise for some filing.

Last shot is the part after all the machine work I am going to do. I'll put the two case halves in my tumbler for some additional cleanup.

Weight loss was 5.5 ounces. This part weighs in at 2.05 oz.

I had a ball doing this work. One thing I learned. I have a -lot- to learn...

I received two new crank bearings in the mail today so once I finish cleaning the cases up I'll disassemble the good engine and transfer the crank, piston and cylinder over to this crankcase.

More pics as work progresses.

Thank you all for looking.

 

[doubletop]

................. We made 1/4 and 1/5 scale target drones that used Quadra and Harris two stroke engines............ They got sent up, and often came down in pieces, kind of like RC planes, (sometimes!).

Before I got to Deans post drones were going through my mind while reading this,. You wouldn't want to be near to one of these coming down out of control. However, I've no immediate plans to visit Oklahoma

That said, in days gone by I was a Harrier techie. We would go and park ourselves in the woods, for a few weeks at a time, somewhere in Germany and the aircraft would use a field as an airstrip. One of these deployments was adjacent to the local model aircraft club and they decided to treat us to an air display. No I/C or electric engines for these guys they we using pulse jets (they had developed these things 30 years before). Didn't those things go!! we'd seen nothing like it. Strangely nobody seemed to be concerned of the consequences if one of these things went out of control an poked a hole in one the multi million pound Harriers. As it happens it was event free.

(wrong squadron)

Back to the build
Pete

 

[zeeprogrammer]

That would have been a pretty scary operation for me.

Watching with interest Mike.

 

[Troutsqueezer]

Can't tell you how many times I've had to buy and replace broken rotor blades for the helicopters I've been through. Finally, I bought the Real Flight Simulator and flew those instead of the real ones. Had a much larger choice of copters to choose from too and wasn't afraid to fly inverted. Not to mention being able to fly jets and airliners.


I've been thinking lately about taking up RC airplanes again when I retire and like you, I think I will stick with the big ones. Easier to see, easier to fly, harder to store and haul around though.

Engines for those are expensivo, I can see why you would like to convert one. I'll be hanging around too.

 

[bearcar1]

Say Mike, an interesting project you have started. What type of bearings are you planning to use for your conversion? Wouldn't there have to be some sort of axial thrust loads to contend with? I'm just curious as normal ball bearings I would not think would be able to stand up to the thrust loads of swinging such a large propellor.

BC1
Jim

 

[Twmaster]

Pete: Pulse Jets! That would be neat to see.

Zee: Scary operation how?

Trout: I'm likely going to give up on helis as my vision is getting that bad. I've been flying planks for most of the last 20 years. I like it too much to be forced away just yet.

Jim: Nothing special about the bearings. All of the aero engines I've seen just use plain ball bearings for crankshaft support.

Pat: Dang. I think I can see that one!

Thanks for stopping in folks. I appreciate the comments.

I've got some silly house work getting in the way of shop time today....

 

[Deanofid]

Looks good, Mike. That's a really worthwhile weight loss too, not to mention getting it configured
to mount up for use in a bird.

 

[zeeprogrammer]

Scary for me.
It's one thing to take raw material and machine it. If I screw up...I get more raw material. If it were me machining that....I'd have to get a whole new system. ;D