4 cylinder inline aero engine

[Art K]

Dougie,
I just looked over your build here, it looks great! I do like old airplane engines though.
Art

[kuhncw]

Dougie,

Thanks for the update on the open twin.  It looks good.  You can definitely waste fire the twin.  I build my two cylinder Silver Bullet with the same crank configuration as your twin.  Runs great with the wasted spark firing into the intake stroke on the following cylinder.

Thanks also for posting the contruction photos and notes for your 4 cylinder.

Chuck

[Zephyrin]

Thanks for all these posted pictures, lot of informations !
"all bronze" conrods, built up crankshaft, very interesting.

[cwelkie]

Thanks for adding all the pictures and updates Dougie.
No reason your approach to the ignition system shouldn't work out fine.  I can think of nothing that would stop you from splitting up the low voltage trigger side of things from the HT distributor pieces.  Just more parts to build - but who's counting anyway?
Charlie

[fourstroke]

Hi Chuck

What kind of coil do you use for the wasted spark system?

Dougie

[kuhncw]

Hi Dougie,

I use an ignition module from S/S Machine and Engineering, LLC.  http://www.cncengines.com/ic.html

The module is shown on his order page. http://www.cncengines.com/orderpage.html  It is listed as a TWIN CYLINDER CDI.  Scroll down the page to find it.

I use two magnets 90 degrees apart, running at cam speed, and a Hall Sensor to fire the coil module. 

Roy sells quite a wide range of ignition related items for model engines.

Chuck

[fourstroke]

Thanks Chuck

Thats a good site

Dougie

[fourstroke]

Hi
Here are a few pics of the dummy magneto and the distributor
The first pics shows the body of the magneto, its made from a chunk of aluminium, 19mm wide 20mm over the bosses and 22mm high. The cylindrical mounting  is 6mm and has been secured with loctite, the bearings are 4mm dia
The third pic shows the internals. The brass disc has 4, 3mm holes, spaced 90deg apart for the magnets this will be fixed to the camshaft with a grubscrew. The sensor mount is made from tuffnol, it has a flat on the opposite side to the one shown to allow for the wires to run from the sensor to the spark pcb, it also has a flat on the bottom to limit the amount this piece can be adjusted around the 6mm mount to adjust the timing. The little brass arm is the lever to adjust the position
The next two show the unit with its steel cover fitted
More pics of the distributor in the next post

Dougie

[fourstroke]

The first two pics in this set show the distributor body, its made from tuffnol and is 16mm dia
The centre hole will take a 9BA csk brass screw and the outer four are 10BA
The rotor is next, it will be a push fit on the shaft, the picture shows the slot being cut for the brass strip to take the spark from the centre to the edge. The strip is held with a 12BA csk screw, an aluminium backplate has been turned to mount it to the rear of the timing case and the brass contacts have been fitted
The internal pic shows the contacts, the central one is spring loaded.

Regards

Dougie

[Roger B]

Very nice    I will be following along   

[fourstroke]

Hi again
Here is another attempt to upload some of the progress on my engine

The first pic shows the cam pairs after filing to shape, the next sows them after hardening and tempering

Next the cam positions were marked onto the camshaft and each cam pair was slid onto the shaft with the bearings inbetween, this arangement was held in the rotary table to set the cam positions. The first pic shows the cams for number one cylinder being fixed into position, to do this I used loctite to fix the cams and using a square end of my setsquare I push this against the two cams in the overlap, TDC position while the loctite sets. The rotary table is moved 90 deg to set number three cylinder in the same way then four then two. The finished camshaft is shown in the last pic with the bearings fixed in their respective position.
When the shaft is finally fixed to the drive gear all I have to do is set number one cylinder to TDC, position the cams at the correct setting and all the others will be automatically in their correct position
I hope this uploads OK this time
As always, any comments or advice will be appreciated
Dougie

[fourstroke]

That was easy, looks like the move to a new host has worked

Before I assembled the crankcase and fitted the crank I sandblasted the top and bottom halves, gear housing and front bearing housing to give everything a "cast" look.

I decided it was time to start the mount for the engine, I want it to look as much like an actual airframe as possible so designed a tubular mount that will incorporate all the throttle and ignition advance/retard controlls, switches ignition coil and fuel tank.
I started with 6mm tube, two pieces of 6mm flat, 14,x12mm were silver soldered in position to corespond with the flats on the lower crankcase, thats the first pic.
Next I made a litte jig to hold the tube while it was cut to the angles required with a 6mm carbide cutter, either in the lathe or mill depending on whether the cut was angled or straight, thats shown in the second pic

The pieces were fixed to a ceramic board and jigged up to silver solder them. Next the main uprights were formed and with the two side frames screwed into position on the lower crankcase these were brazed to the uprights, thats the next two pics.

Finally the partially assembled engine is shown fitted to the mount, on a temporary base, with the cylinders fitted ready to lock the camshaft to its final position

Regards

Dougie

[Admiral_dk]

Everything looks great so far - awaiting the rest of the build with anticipation 

[zeeprogrammer]

I just came across this. This looks good.

It's not clear to me the size of the engine. Are their plans.

Very cool project!

[fourstroke]

Thanks for the comments, I appreciate them.

Zee, hi, the engine has a 21mm bore and 20mm stroke, I dont have any plans other than the general arrangement I drew to get a rough idea of how it would look, everything else is just made up as I go along. Sometimes I have to reign myself in as I can get carried away with adding this and that till I get bored and the project never gets finished.

With the cams set in their respective position on the shaft it was time to fix the shaft to the drive gear.
The first pic shows the little "jig" I made to set the cams up with number 1 cylinder at TDC. This is just two equal length pieces of 1/8" silver steel held to a plate with a couple of screws. In use, this is pushed through the tappet guides till the rods contact the flank of the cams at TDC position, pressing on this jig forces the cams to stay in position while I applied loctite to the shaft and gear and fixed them in position. Its shown in use in the next two pics
The complete gear train is the next pic

Finally there are a couple of pics of the fuel tank I made from brass sheet fitted to the mount with the engine in place

Comments or thoughts welcome

Regards

Dougie