Microlighters

Any updates ?

t-bird wrote:Any updates ?

Very slow week/weekend... Had the AP over for a quick double check, and I need to do some changes - one of which involves removing the engine... Decided not to finish the engine installation until that is done. Working on the baffels at the moment, but only managed one single piece this weekend.

There is so little left to do, but somehow it seems to take forever .

Hang in there bud...nearly done.

justin.schoeman wrote:

t-bird wrote:Any updates ?

.

There is so little left to do, but somehow it seems to take forever .

Justin, take heart my friend, it DOES get done at some stage. The clients i build aircraft for often try to rush me on but they have not built an aircraft yet and therefore DONT understand the meaning of 90% done 90% to go Finishing has to be good in order to have a "good" aircraft.
Regards
Jeaan

Another week, and not much to show for it. In amongst the ongoing work, I have been redoing some stuff the AP did not like (to be honest, I did not like it much either, which made redoing it a bit easier).

Firstly, I had a rather intricate cable operated throttle mixer bolted to the inside, bottom of the firewall. It worked well, but was finicky. Disturb the cable routings slightly, and throttle friction becomes unpleasantly high. After discussingwith the AP, we desided that the only option was to do something in the 20mm (eek!) gap to the sides of the fuel tank. This is the result:
The entire mechanism is slick and smooth, and incredibly solid. Uses rod end bearings for the pushrods, and brass in teflon bushes for the torque tube. A massive improvement over the previous attempt.

Still waiting for new engine mount spacers (note to self - think first... I assumed that engine mount bolts would be used in tension - I mean there is this huge prop tugging away up front, right? Think twice. Prop produces ~150kg max of thrust, but engine weight at max G is ~540kg. Sheer load is much higher - so stacking washers is NOT an option ). Anyway, waiting for someone to make up spacers for me - I must get myself a lathe - depending on other people for the tiniest little things is a serious pain in the butt...

Other than that, I finished moulding all the composite baffle parts - those used in the cooler areas, around complex curves (i.e. around the cylinders). Had to post cure the high temp epoxy though. Had them in my oven for just on 48 hours. Gonna be an interesting electricity bill!

Looks good.
Where are you going to hanger ?

Continuing with the ancient Chinese torture of 'death by a thousand cuts'. Many tiny tasks done, many to go. Finished the throttle linkages and firewall pass-through. Still got to do the mixture (done a trial fit, but still got to do the final fit).

The big jobs tonight were the oil system. Fortunately I remembered to torque the drain plug before fitting the rest. Decided to add a safety wire, just to be sure.
Fitted the oil system. Nice, compact and simple - short pipes, and everything bolts on as one unit, which can swing free for oil changes.
Pre-oiled the engine with a (RIP) 'Bob Hoover Pre-Oiler(TM)'. Get a cheap garden pressure spray, cut off the spray nozzle, and fit a 1/8" NPT fitting. Fill it with oil. Now pump the pressure sprayer, and hand crank the engine until oil comes out of the rockers faster than the sweat is pouring off your face. Since the rockers are at the very end of the oil galleys, you can be pretty sure the entire engine is well lubed.
Tomorrow, I need to finish a bracket for the remote handle for the fuel cock, then I can refit the panel, and hook up and test the instruments. Then it is just fuel and fire!

Hi Justin

Please make a video of the first start up.

Just said a loud (but not too expensive - I hope) expletive... I shouldn't work so late at night - I get sloppy.

Was busy tightening the valve covers. Since they are aftermarket bolt-on covers (not the stock clip on covers), there is no torque spec in the service manual. And Aeroconversions aren't nice enough to supply one either. Now there are thick cork gaskets and rubber washers involved, so everything is hugely compressible. So I had the bright idea to just tighten it until the bolts start stiffening up (which should happen once the gaskets start approaching their compression limit), and then back it up a little.

What I didn't realise was that the cover itself was flexing - until it cracked... Going to have to take some time off tomorrow, and hunt for a new one .

Aside from that, I finished the bracket for the remote handle for the fuel cock, and refitted the panel. Hooked up the electrics and tested the ignition systems. The primary produces a pretty wimpy spark at cranking speeds, but the secondary produces a mean spark. Just got to finish the hookups and set the timing - then it is just fuel to go!

No second hand (or even new) bolt-on valve covers in Pretoria, or Joburg. Will have to try have the crack welded...

Justin I'm also a great believer in pre-oiling. With the tappet covers we always put in stops so that the stop is such that the the gaskets and O-rings are then preloaded.

Good Luck

Cheers Oupa-G

OK braised up the valve cover - it will just have to do for the first engine tests, and cowl plug. New ones should arrive in SA in a week or two.

Set up all 4 *gack* ignitions to fire at pretty much the same time - while turning on the starter. SInce this is fixed timing, I doubt it will differ when running, but I suppose some sucker will have to get behind the prop of the running engine to check - don't like that idea at all.

Need to pick up a few hose clamps for the intake manifold, and swing by KittyHawk for some fuel, but it should still start tomorrow!

Still not running... Took much longer to fit the carb than expected (you actually need to completely strip the aerocarb to fit the throttle cable.

Engine is now in runnable condition, but the prop is not torqued yet - got right to the end before realising that the prop needs to be torqued with an allen key, and I do not have such a fitting for my torque wrench . See what I can dig up at Builders tomorrow...

OK - Blew my record today. Up to this point, every engine I have built has started on the first crank. This one did not. It took a second attempt with a bit more throttle - but then it started and ran beautifully! Horribly, horribly rich though. It only peaks in the last few mm of mixture knob movement, and takes some serious nursing to bring the RPM up. Going to have to sit down with the Aerocarb tuning manual, and see if I can set it up properly.

Aside from that, oil temp is good, mag checks are good, no oil leaks, no fuel leaks - in fact everything seems perfect, except for the thaco - I can't seem to get the RDAC to pick up the revs from the alternator.

TODO list now:
1) cooling baffles
2) cowling
3) rev counter
4) check throttle (sticky under engine load)
5) tune-up
6) lots-and-lots of paper work
7) FLY!

Congratulations with the first strart up