Aurora K 600 R/C
03-31-2008 | 06:33 AM
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From: Hervey Bay Queensland, AUSTRALIA
Aurora K 600 R/C
After posting on various threads enquiries about Aurora engines, I thought I would start one of my own.
The reason is - today the postman delivered an Aurora K 600 BB R/C (.35 cu). A sardonic joke at my own expense perhaps?
A week ago I went onto Carlson Engine Imports site and ordered a K 650. Mr Carlson emailed me back and politely said unfortunately he was out of stock. A K 600 R/C was offered in substitution. As it was on special ($90-) I accepted.
I will not post pics of the engine here. My digital camera is of poor quality. Here is a link to images of the K 500. By clicking on "baja" the images will be blown up. The K 600 engine looks essentially similar to the K 500 in all respects. Cosmetically, the engine I have differs ... for the better in my opinion.
http://www.rojobcn.com/technic/avion/aurorak500.htm
I will report my findings over a period of time, ending up with a bench report when carrying out running in. I have no aircraft to put it in at the moment.
Initial Impressions:
The engine is delivered in a stout, well made plain white box. The cardboard is thick and of a strength that has not seen for packaging of mainstream engines in decades.
Inside, the engine sits in an inner protective casing of cushioning polystyrene pieces. The engine itself is packed in a ziplock plastic bag. Padding in the form of crumpled paper that looks like old fashioned butcher's paper is used to ensure the contents as packed cannot move about.
Instructions are "quaint" and are printed on a folded sheet of A4 gloss buff paper, in a type set reminiscent of the 1940's. The english is a little convoluted but far, far better in grammar and syntax than many far eastern instructions.
As one would expect from a pukka manufacturer in a former British colony. Pip pip!
Prop and fuel recommendations (olde english brew of course!) are given, no surprises with the recommendations, however there is no schematic or parts list.
The engine is assembled with an R/C carb attached, but the main needle is seperate and is to be installed. You screw it on
Things that I notice that really stand out:
1. The all metal carb is finished in satin black, which is very nicely done .. very similar to a black metal bodied Irvine carb.
2. The cooling fins are nicely finished in satin black, looks good though a little sparse in application in places.
3. The head is separate, and is bolted on by three short slot head bolts. It seems to be turned from solid and is finished in a high grade gold anodise. Looks very attractive, and matches well with ...
4. The included round base spinner nut and prop washer, both of which are gold anodised, and finely finished. The spinner is of a pleasing contour. It's not unlike the items Du-Bro sell but not quite as pointy, and its diameter matches that of the prop driver, which appears to be well turned; free of any marks, and which sits on a split collet. A standard prop nut is included as an alternative to the spinner. A tommy bar is also included for tightening the spinner up. Very thoughtful.
5. Nice fine finished aluminium screw-in backplate, a-la PAW again, with milled slots for removal / refitting. "India" is stamped in the recess ... the only identification on the engine. A fibre gasket seals it where the flange meets the back of the crankcase.
Case Casting
The block is unitary construction. The finish is of a rough dull grey bead blast. The cylinder is that ... cylindrical. Die marks are clean with no evidence of hand filing to finish. There are no pock marks or signs of slumping in the alloy. There are a couple of minor nicks on the outer surface of the mounting lugs, however these are not at all deep and I suspect relate to "mounting" at the factory for assembly purposes. Oddly, there are no serial numbers anywhere, or any marking noting the name of the manufacturer or model/ displacement. PAW - like in that regard. Some waxy residue has stained it in places.
The exhaust collector is a clamp-on ring device, again quite PAW like, with a stubby muffler attached pointing away from the head. This has an internal baffle of the "pepper pot" style (like the holes in a colander) through which exhaust gases eventually exit. A short stinger finishes it off, to which a diverter or coupler could be attached, if so desired. The muffler is angled at 45 degrees from the crankshaft, on the usual side. There is no pressure nipple. None would be required.
The carb appears to be held in place by an English Irvine / PAW type of set - up. That is, two grub screws holding the inlet shank. Commendably, the bosses are thick, and are raised proud of the inlet, so there is plenty of "meat" for the threads of the securing screws.
Here is when we see what to me is poor looking hardware ... two slot head screws, one of which has the head very chewed up by the screwdriver used to set it home. I have not yet backed these out.
Carb
Nice looking black rectangular solid metal unit, of the fuel metering twin needle type. Main needle is finely tapered and the needle body is held by a firm and effective ratchet clip, it looks PAW like except for the knurling on the body that interacts with the spring clip to hold the setting. It screws a long way over the inlet needle ... nice, there are no "O" rings to wear and leak here! The inlet nipple is hand made and silver soldered onto the main needle. Frankly, it looks agricultural but is nicely done and the solder is smooth. it just looks ... hand made?
Idle needle screws into the Carb from the other side and is easily accessable as it is well proud of the carb, held under firm tension by a well made spring. This idle screw will not wander! I like it. A barrel retaining screw, also under spring tension, holds the barrel in place and sits on top of the carb, angled slightly backwards. The angled groove for the barrel is well ground, no burrs. Barrel is tensioned by a wide circular spring which sits in the carb body on the inlet side and pushes the barrel up nicely against the retaining screw ... so tha barrel will not move side-to side. Why do PAW not make twin needle carbs like this?
The fit of barrel to body is adequate ... like most engines. Choke diameter is about 5 mm. I did not measure it.
Throttle arm, as delivered, is steel and is on the upper side of Carb (?) ... Why? so, I remove the idle needle and spring, release the securing nut, and I turn it round to the more usual position. I nip it up (using a 5/26" hex socket), replace idle needle and spring ... all good!
Carb is sealed to the intake by the usual black "O" ring. It is firmly compressed, so air leaks are unlikely.
OVERALL IMPRESSION .... NOT TOO BAD at all!
Don't like the prop washer for use with the prop nut though, its just an anodised flat washer - for use only with the spinner. Being flat, if you use the nut, please use a contoured proper prop washer, preferably steel, though alloy would do. I will find one in my box of bits for use with the prop nut.
OK, now for the bad (?) news!
Problem / Challenge
1. The carb barrel is locked solid .. I cannot move it with the throttle arm. Hmmm ... think
* Apply spray oil (WD 40) liberally into carb. Wait 2 hours.
* Not budge .. so I remove idle needle, spring, nut, throttle lever.
* replace nut, screw all the way down on to barrel
* remove barrel retaining screw and spring on top of Carb
And keep turning the screw with the socket drive ... as it hit the bottom of the thread, finally, the barrel slowly gives up and gradually moves! It was held fast by congealed preservative that has hardened to a dark brown tar like substance. I spin the barrel a few times and pull it out of the carb body, a few sprays of WD 40 and some wiping and the gum is gone, reassemble carb, and it moves smoothly once I adjust the barrel retaining screw. Phew! the gamble paid off!
2. The crankshaft is locked solid! Won't turn! Don't panic, it is no doubt a victim of the gummed up preservative again. I place a prop on it (usual 1/4 diameter fitting) (11x6 Graupner), nip up the spinner and try to turn it over ... no luck! Still locked solid. I will soak the engine in petrol for a few days to get it to loosen up. Prop tips move 2~3 mm ... ok.
I will report back further once the engine has had a soak.
I may remove the backplate and inspect inside the case ... if only to remove the gummed up preservative [>:] ... Once I get the thing turning!
I have to say, the bling factor on this engine is superb ... if you like that sort of thing .... similar to a Saito gold knight ... the gold head and spinner really sets off the black carb and fins !!!
The reason is - today the postman delivered an Aurora K 600 BB R/C (.35 cu). A sardonic joke at my own expense perhaps?
A week ago I went onto Carlson Engine Imports site and ordered a K 650. Mr Carlson emailed me back and politely said unfortunately he was out of stock. A K 600 R/C was offered in substitution. As it was on special ($90-) I accepted.
I will not post pics of the engine here. My digital camera is of poor quality. Here is a link to images of the K 500. By clicking on "baja" the images will be blown up. The K 600 engine looks essentially similar to the K 500 in all respects. Cosmetically, the engine I have differs ... for the better in my opinion.
http://www.rojobcn.com/technic/avion/aurorak500.htm
I will report my findings over a period of time, ending up with a bench report when carrying out running in. I have no aircraft to put it in at the moment.
Initial Impressions:
The engine is delivered in a stout, well made plain white box. The cardboard is thick and of a strength that has not seen for packaging of mainstream engines in decades.
Inside, the engine sits in an inner protective casing of cushioning polystyrene pieces. The engine itself is packed in a ziplock plastic bag. Padding in the form of crumpled paper that looks like old fashioned butcher's paper is used to ensure the contents as packed cannot move about.
Instructions are "quaint" and are printed on a folded sheet of A4 gloss buff paper, in a type set reminiscent of the 1940's. The english is a little convoluted but far, far better in grammar and syntax than many far eastern instructions.
As one would expect from a pukka manufacturer in a former British colony. Pip pip!
Prop and fuel recommendations (olde english brew of course!) are given, no surprises with the recommendations, however there is no schematic or parts list.
The engine is assembled with an R/C carb attached, but the main needle is seperate and is to be installed. You screw it on
Things that I notice that really stand out:
1. The all metal carb is finished in satin black, which is very nicely done .. very similar to a black metal bodied Irvine carb.
2. The cooling fins are nicely finished in satin black, looks good though a little sparse in application in places.
3. The head is separate, and is bolted on by three short slot head bolts. It seems to be turned from solid and is finished in a high grade gold anodise. Looks very attractive, and matches well with ...
4. The included round base spinner nut and prop washer, both of which are gold anodised, and finely finished. The spinner is of a pleasing contour. It's not unlike the items Du-Bro sell but not quite as pointy, and its diameter matches that of the prop driver, which appears to be well turned; free of any marks, and which sits on a split collet. A standard prop nut is included as an alternative to the spinner. A tommy bar is also included for tightening the spinner up. Very thoughtful.
5. Nice fine finished aluminium screw-in backplate, a-la PAW again, with milled slots for removal / refitting. "India" is stamped in the recess ... the only identification on the engine. A fibre gasket seals it where the flange meets the back of the crankcase.
Case Casting
The block is unitary construction. The finish is of a rough dull grey bead blast. The cylinder is that ... cylindrical. Die marks are clean with no evidence of hand filing to finish. There are no pock marks or signs of slumping in the alloy. There are a couple of minor nicks on the outer surface of the mounting lugs, however these are not at all deep and I suspect relate to "mounting" at the factory for assembly purposes. Oddly, there are no serial numbers anywhere, or any marking noting the name of the manufacturer or model/ displacement. PAW - like in that regard. Some waxy residue has stained it in places.
The exhaust collector is a clamp-on ring device, again quite PAW like, with a stubby muffler attached pointing away from the head. This has an internal baffle of the "pepper pot" style (like the holes in a colander) through which exhaust gases eventually exit. A short stinger finishes it off, to which a diverter or coupler could be attached, if so desired. The muffler is angled at 45 degrees from the crankshaft, on the usual side. There is no pressure nipple. None would be required.
The carb appears to be held in place by an English Irvine / PAW type of set - up. That is, two grub screws holding the inlet shank. Commendably, the bosses are thick, and are raised proud of the inlet, so there is plenty of "meat" for the threads of the securing screws.
Here is when we see what to me is poor looking hardware ... two slot head screws, one of which has the head very chewed up by the screwdriver used to set it home. I have not yet backed these out.
Carb
Nice looking black rectangular solid metal unit, of the fuel metering twin needle type. Main needle is finely tapered and the needle body is held by a firm and effective ratchet clip, it looks PAW like except for the knurling on the body that interacts with the spring clip to hold the setting. It screws a long way over the inlet needle ... nice, there are no "O" rings to wear and leak here! The inlet nipple is hand made and silver soldered onto the main needle. Frankly, it looks agricultural but is nicely done and the solder is smooth. it just looks ... hand made?
Idle needle screws into the Carb from the other side and is easily accessable as it is well proud of the carb, held under firm tension by a well made spring. This idle screw will not wander! I like it. A barrel retaining screw, also under spring tension, holds the barrel in place and sits on top of the carb, angled slightly backwards. The angled groove for the barrel is well ground, no burrs. Barrel is tensioned by a wide circular spring which sits in the carb body on the inlet side and pushes the barrel up nicely against the retaining screw ... so tha barrel will not move side-to side. Why do PAW not make twin needle carbs like this?
The fit of barrel to body is adequate ... like most engines. Choke diameter is about 5 mm. I did not measure it.
Throttle arm, as delivered, is steel and is on the upper side of Carb (?) ... Why? so, I remove the idle needle and spring, release the securing nut, and I turn it round to the more usual position. I nip it up (using a 5/26" hex socket), replace idle needle and spring ... all good!
Carb is sealed to the intake by the usual black "O" ring. It is firmly compressed, so air leaks are unlikely.
OVERALL IMPRESSION .... NOT TOO BAD at all!
Don't like the prop washer for use with the prop nut though, its just an anodised flat washer - for use only with the spinner. Being flat, if you use the nut, please use a contoured proper prop washer, preferably steel, though alloy would do. I will find one in my box of bits for use with the prop nut.
OK, now for the bad (?) news!
Problem / Challenge
1. The carb barrel is locked solid .. I cannot move it with the throttle arm. Hmmm ... think
* Apply spray oil (WD 40) liberally into carb. Wait 2 hours.
* Not budge .. so I remove idle needle, spring, nut, throttle lever.
* replace nut, screw all the way down on to barrel
* remove barrel retaining screw and spring on top of Carb
And keep turning the screw with the socket drive ... as it hit the bottom of the thread, finally, the barrel slowly gives up and gradually moves! It was held fast by congealed preservative that has hardened to a dark brown tar like substance. I spin the barrel a few times and pull it out of the carb body, a few sprays of WD 40 and some wiping and the gum is gone, reassemble carb, and it moves smoothly once I adjust the barrel retaining screw. Phew! the gamble paid off!
2. The crankshaft is locked solid! Won't turn! Don't panic, it is no doubt a victim of the gummed up preservative again. I place a prop on it (usual 1/4 diameter fitting) (11x6 Graupner), nip up the spinner and try to turn it over ... no luck! Still locked solid. I will soak the engine in petrol for a few days to get it to loosen up. Prop tips move 2~3 mm ... ok.
I will report back further once the engine has had a soak.
I may remove the backplate and inspect inside the case ... if only to remove the gummed up preservative [>:] ... Once I get the thing turning!
I have to say, the bling factor on this engine is superb ... if you like that sort of thing .... similar to a Saito gold knight ... the gold head and spinner really sets off the black carb and fins !!!
04-01-2008 | 04:57 PM
#4
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From: Hervey Bay Queensland, AUSTRALIA
RE: Aurora K 600 R/C
Bad news.
I pulled the engine out of it's solvent bath and bolted up the prop.
A good twist on the prop, and the crankshaft set itself free, and turned.
The bad news is, the crankshaft is binding on the case! It cannot turn over freely in its races.
I will re-package the engine into its box and send it back to Carlson Engine Imports for exchange.
It is a pity, as in many ways the engine seems well enough made and is of apparently sound design. The finish on my example is superior to that shown in the link above. I was really looking forward to firing it up and reporting on its running qualities and performance.
However, it seems that quality control is an issue; and that purchasing an Aurora something of a lottery as to whether you will get a good one or not.
I may report here again (take 2!) once the replacement is to hand.
I pulled the engine out of it's solvent bath and bolted up the prop.
A good twist on the prop, and the crankshaft set itself free, and turned.
The bad news is, the crankshaft is binding on the case! It cannot turn over freely in its races.
I will re-package the engine into its box and send it back to Carlson Engine Imports for exchange.
It is a pity, as in many ways the engine seems well enough made and is of apparently sound design. The finish on my example is superior to that shown in the link above. I was really looking forward to firing it up and reporting on its running qualities and performance.
However, it seems that quality control is an issue; and that purchasing an Aurora something of a lottery as to whether you will get a good one or not.
I may report here again (take 2!) once the replacement is to hand.
04-01-2008 | 11:04 PM
#7
Senior Member
RE: Aurora K 600 R/C
Probably before sending the engine back, it would have been better to remove the backplate and flush the insides out with Acetone. Its
quite possible some swarf was jamming the races, or even some congealed oil. I once had a brand new ENYA 35 Special (twin ball races) which felt very rough in the bearings, but after removing the front housing and spinning the shaft in Acetone, the roughness
disappeared - just some hardened oil. BOB
quite possible some swarf was jamming the races, or even some congealed oil. I once had a brand new ENYA 35 Special (twin ball races) which felt very rough in the bearings, but after removing the front housing and spinning the shaft in Acetone, the roughness
disappeared - just some hardened oil. BOB
04-01-2008 | 11:53 PM
#8
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From: Hervey Bay Queensland, AUSTRALIA
RE: Aurora K 600 R/C
I've thought some more about it.
I will do that Bob. Nothing to lose by unscrewing the back plate and having a good look.
Who knows what I may discover .... I will post back.
I will do that Bob. Nothing to lose by unscrewing the back plate and having a good look.
Who knows what I may discover .... I will post back.
04-02-2008 | 12:09 AM
#9
Senior Member
RE: Aurora K 600 R/C
Try this method of removing the backplate - take a short length of round wood (such as from a broom handle), and gradually grind it
down with a slight taper, until the end will just go into the backplate. Tap it in as far as it will go, then you can grip the wood with pliers
or whatever to unscrew the backplate - saves burring the blasted thing as nearly always happens ! BOB
down with a slight taper, until the end will just go into the backplate. Tap it in as far as it will go, then you can grip the wood with pliers
or whatever to unscrew the backplate - saves burring the blasted thing as nearly always happens ! BOB
04-02-2008 | 05:46 PM
#11
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From: Hervey Bay Queensland, AUSTRALIA
RE: Aurora K 600 R/C
Excellent tip 74/7!
I hate butchered backplates on PAW's and the like. You see this quite often on the second hand examples appearing on eb*y.
To update:
Last night I felt a renewed sense of resolve, and I retrieved the engine from its hydrocarbon bath (where I had left it in disgust)and drained the solvent (some old weed eater two stroke mix) from it.
I had a length of hard plastic U-shaped conduit extrusion in the scrap bin. It is square U in profile and the top part (to cover the wires within) snaps on. It is used for computer cabling. I recently helped myself to some scraps from my workplace. Took it home.
Now, the backplate on the Aurora is well thought out. On PAW's, the milled slots are radiused inwards and they are a * $9%t * of a thing to get off without the correctly curved tool. A straight edge on a PAW backplate (at least the backplates on the one's I have) won't do the job properly.
Not so here. The slots on the Aurora backplate are milled straight across the flange. So, not wanting to damage the slots, I butt the backplate flange up against the plastic lip on the conduit off-cut ... and I have a win! The lip fits perfectly and the plastic will not deform the aluminium!
[8D] Cool ... with a quick twist, it unscrews without a hitch.
Now, the thread on the blackplate recess is quite deep, and it is extremely fine, but well formed. The mating thread in the crankcase is also nicely worked. The backplate screws on and off the crankcase very smoothly, but beware ... cross threading would be just too easy, so I make a mental note to go about re-assembly slowly and gently. I will use a little air tool oil on the threads when I do it back up.
As for the gasket that seals the backplate to the crankcase, well it is a black rubber filled fibre affair, and is hand cut to a round shape! Roughly done; but it is "OK" for the job, and it hasn't beem torn or damaged by the removal of the backplate. I think about removing it, but there is no need, so I leave it there.
There are some slight concentric marks on inner surface of the backplate, from where the big end has rubbed against it (no doubt from my earlier efforts when turning the engine over). I may scource a sightly thicker fibre gasket when re-assembling, like the type used on tap (US faucet) fittings, as maybe there was a slight binding there ... or before re-assembly, I might just relieve the backplate a little using the "flat glass and oily 600 grit glasspaper" method. The first option will be easier. I'll see.
Peek inside ... OK, if you've ever looked inside a PAW, that's pretty much what you see. Crank and pin are unremarkable. Conrod is a steel tubular affair and the little and big ends are both pretty hefty! Bronze bushed. This conrod seems to be way, way over what is required for a .35... but it is clearly made strong to take the tough punishment that only an over compressed diesel can mete out.
It is hand finished, and filing marks are very evident. Not surface finished with any great aesthetic finesse at all ... workmanlike is the word! I think I will finish smooth this item off myself.
I laugh when I see how clearance on the outside of the big end to the crankase has been "hand" fitted (i.e. filed!) to tolerance by a series of flat swipes with a file. Very "hand made", very old school manufacturing! But nonetheless perfectly effective. This has not been made by a CNC robot! Hey, lets face it, it does not need YS fuel pump tolerances
!
The steel liner is thick. It has 4 intake gas transfer ports radially milled around it, to allow the incoming charge up into the combustion chamber. I can't see too clearly, but looks to me just like a PAW-type gas transfer set up. It has a very substantial iron piston as well. All looks well enough made and well put together.
Looking around inside the case carefully now ...
No surprise - there is obvious swarf ... fairly fine though ... so I slush what I can see out with a few quick dunks of the bottom of the engine in the petrol bath, and then carefully wipe out what I can get to down through the backplate entrance.
Gosh, its still "rough" to turn over .... so I inject some air tool oil (a healthy squirt) in the intake port (I have the carb off) and around the main bearing through the back , and turn it over a couple of times. Oil mixes with some dribbles of petrol still in there. I tip the nose up, and a metallic sparkly glistening sludgy mix of oily petrol flows out. The oil has "floated" out much more of the swarf!
Bearings feel really, really lumpy. I suspect they may be "cream crackered" (US: trashed) by the machining particles that were there. A lot could still be in there. Or maybe the bearings are just gummed up, if I am lucky. Can't tell just yet.
I tentatively turn it over (after trickling the oil out), and it feels a bit smoother, the air tool oil still in there has helped a lot.
I decide ... No question about it, it's getting a full strip down. A mechanic friend has a puller to get the prop driver off ... bearings must come out, rest will be easy.
I'll do it on the week-end I think
To be continued ...
I hate butchered backplates on PAW's and the like. You see this quite often on the second hand examples appearing on eb*y.
To update:
Last night I felt a renewed sense of resolve, and I retrieved the engine from its hydrocarbon bath (where I had left it in disgust)and drained the solvent (some old weed eater two stroke mix) from it.
I had a length of hard plastic U-shaped conduit extrusion in the scrap bin. It is square U in profile and the top part (to cover the wires within) snaps on. It is used for computer cabling. I recently helped myself to some scraps from my workplace. Took it home
.Now, the backplate on the Aurora is well thought out. On PAW's, the milled slots are radiused inwards and they are a * $9%t * of a thing to get off without the correctly curved tool. A straight edge on a PAW backplate (at least the backplates on the one's I have) won't do the job properly.
Not so here. The slots on the Aurora backplate are milled straight across the flange. So, not wanting to damage the slots, I butt the backplate flange up against the plastic lip on the conduit off-cut ... and I have a win! The lip fits perfectly and the plastic will not deform the aluminium!
[8D] Cool ... with a quick twist, it unscrews without a hitch.
Now, the thread on the blackplate recess is quite deep, and it is extremely fine, but well formed. The mating thread in the crankcase is also nicely worked. The backplate screws on and off the crankcase very smoothly, but beware ... cross threading would be just too easy, so I make a mental note to go about re-assembly slowly and gently. I will use a little air tool oil on the threads when I do it back up.
As for the gasket that seals the backplate to the crankcase, well it is a black rubber filled fibre affair, and is hand cut to a round shape! Roughly done; but it is "OK" for the job, and it hasn't beem torn or damaged by the removal of the backplate. I think about removing it, but there is no need, so I leave it there.
There are some slight concentric marks on inner surface of the backplate, from where the big end has rubbed against it (no doubt from my earlier efforts when turning the engine over). I may scource a sightly thicker fibre gasket when re-assembling, like the type used on tap (US faucet) fittings, as maybe there was a slight binding there ... or before re-assembly, I might just relieve the backplate a little using the "flat glass and oily 600 grit glasspaper" method. The first option will be easier. I'll see.
Peek inside ... OK, if you've ever looked inside a PAW, that's pretty much what you see. Crank and pin are unremarkable. Conrod is a steel tubular affair and the little and big ends are both pretty hefty! Bronze bushed. This conrod seems to be way, way over what is required for a .35... but it is clearly made strong to take the tough punishment that only an over compressed diesel can mete out.
It is hand finished, and filing marks are very evident. Not surface finished with any great aesthetic finesse at all ... workmanlike is the word! I think I will finish smooth this item off myself.
I laugh when I see how clearance on the outside of the big end to the crankase has been "hand" fitted (i.e. filed!) to tolerance by a series of flat swipes with a file. Very "hand made", very old school manufacturing! But nonetheless perfectly effective. This has not been made by a CNC robot! Hey, lets face it, it does not need YS fuel pump tolerances
!The steel liner is thick. It has 4 intake gas transfer ports radially milled around it, to allow the incoming charge up into the combustion chamber. I can't see too clearly, but looks to me just like a PAW-type gas transfer set up. It has a very substantial iron piston as well. All looks well enough made and well put together.
Looking around inside the case carefully now ...
No surprise - there is obvious swarf ... fairly fine though ... so I slush what I can see out with a few quick dunks of the bottom of the engine in the petrol bath, and then carefully wipe out what I can get to down through the backplate entrance.
Gosh, its still "rough" to turn over .... so I inject some air tool oil (a healthy squirt) in the intake port (I have the carb off) and around the main bearing through the back , and turn it over a couple of times. Oil mixes with some dribbles of petrol still in there. I tip the nose up, and a metallic sparkly glistening sludgy mix of oily petrol flows out. The oil has "floated" out much more of the swarf!
Bearings feel really, really lumpy. I suspect they may be "cream crackered" (US: trashed) by the machining particles that were there. A lot could still be in there. Or maybe the bearings are just gummed up, if I am lucky. Can't tell just yet.
I tentatively turn it over (after trickling the oil out), and it feels a bit smoother, the air tool oil still in there has helped a lot.
I decide ... No question about it, it's getting a full strip down. A mechanic friend has a puller to get the prop driver off ... bearings must come out, rest will be easy.
I'll do it on the week-end I think
To be continued ...
04-02-2008 | 06:13 PM
#12
Senior Member
RE: Aurora K 600 R/C
Fiery, your talent is really wasted playing around with "toy" aeroplanes - you should be involved in forensic medicine or similar. Your
attention to detail is remarkable and makes for great reading ! Just in case you (or anyone else ) plan on using Acetone, please read the caveat at - http://www.supercoolprops.com/articl..._situation.php Keep up the excellent work - I can hardly wait for episode 3 ! BOB
attention to detail is remarkable and makes for great reading ! Just in case you (or anyone else ) plan on using Acetone, please read the caveat at - http://www.supercoolprops.com/articl..._situation.php Keep up the excellent work - I can hardly wait for episode 3 ! BOB
04-02-2008 | 07:46 PM
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From: OAKEYQueensland, AUSTRALIA
RE: Aurora K 600 R/C
fiery,
Next time you need to pull the backplate from a PAW , go to your hardware store with the engine and look through the "mudgard washers" - may also be called "gutter washers" these are larger outside dia than regular washers of the same bore/bolt fitting . I have a selection of sizes myself and never fail to find 1 that fits into the PAW slots, just grip the washer in a vice , hold the emgine with the backplate fitted to the washer and twist.
Stewart
Next time you need to pull the backplate from a PAW , go to your hardware store with the engine and look through the "mudgard washers" - may also be called "gutter washers" these are larger outside dia than regular washers of the same bore/bolt fitting . I have a selection of sizes myself and never fail to find 1 that fits into the PAW slots, just grip the washer in a vice , hold the emgine with the backplate fitted to the washer and twist.
Stewart
04-02-2008 | 09:54 PM
#16
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From: Hervey Bay Queensland, AUSTRALIA
RE: Aurora K 600 R/C
Of course! Coach washers! Great idea Stewart. I wonder why it never crossed my mind before?
Certainly a better proposition than my last effort at improvising a tool when removing my PAW .35's backplate.
This involved my small garden trowel (the small type that you hold in one hand and use for potting etc.) clamped in a vise. Yes, I can see you all rolling your eyes, I don't really blame you. Apalling I know.
Well, at least it had a nice, rounded end. Necessity IS the mother of invention!
I cleaned the trowel as best I could first
before I offered up that PAW to it.
All to no avail in the end; I still burred the slots (for which I hang my head in shame).
Certainly a better proposition than my last effort at improvising a tool when removing my PAW .35's backplate.
This involved my small garden trowel (the small type that you hold in one hand and use for potting etc.) clamped in a vise. Yes, I can see you all rolling your eyes, I don't really blame you. Apalling I know.
Well, at least it had a nice, rounded end. Necessity IS the mother of invention!
I cleaned the trowel as best I could first
before I offered up that PAW to it.All to no avail in the end; I still burred the slots (for which I hang my head in shame).
04-03-2008 | 12:03 AM
#17
Senior Member
RE: Aurora K 600 R/C
The coach washers will work OK, but keep in mind they are usually stamped from sheet metal. This means that one edge might be nice
crisp & square, but the other may be slightly rounded, and this is the one that will burr your PAW slots. I don't know exactly how those
PAW guys put their backplates in, but they sure are tight. Hardware store washers are also usually made from mild steel, which can bend under heavy pressure, so I've made up a special PAW one from hard spring steel (large lawn mower blade) with sharp ground edges. BOB
crisp & square, but the other may be slightly rounded, and this is the one that will burr your PAW slots. I don't know exactly how those
PAW guys put their backplates in, but they sure are tight. Hardware store washers are also usually made from mild steel, which can bend under heavy pressure, so I've made up a special PAW one from hard spring steel (large lawn mower blade) with sharp ground edges. BOB
04-03-2008 | 06:42 AM
#18
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RE: Aurora K 600 R/C
Back plate removal?
I have a small square piece 3x5" of .120 (or is it .063) 2024 T3 scrap and I have filed each corner to fit a different engine radius and leaving the last one flat. any way you get the idea and the aluminium is a bit easier on the aluminium backplate.
I have a small square piece 3x5" of .120 (or is it .063) 2024 T3 scrap and I have filed each corner to fit a different engine radius and leaving the last one flat. any way you get the idea and the aluminium is a bit easier on the aluminium backplate.
04-05-2008 | 05:19 PM
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From: Hervey Bay Queensland, AUSTRALIA
RE: Aurora K 600 R/C
OK ... I am writing my notes from the bench as I delve further into this beast ...
To remove the prop driver I borrowed an O.S. puller from a mechanic mate. I will be buying one myself . I was trying to use a car battery terminal puller, but was wrestling with it to avoid gouging the nice finish on the driver. The O.S. puller fitted a treat, and the driver was off in trice without marking it's mirror finish. If you like stripping down model engines, this O.S. puller is a great piece of kit to have.
So:
1. Off with the prop driver collet ... a fairly tight fit on the shaft. A wave of the mini propane torch, it expands and with a gloved hand, it's wriggled off.
2. Front bearing is open faced. I hate open faced front bearings. I won't debate about it. Many european and former eastern block engines use them. I dislike the dribbling or spraying raw fuel syndrome you get with them. It will be replaced with a sealed bearing. I'll remove the rear seal to allow for lubrication if it is not pre-lubed for life.
3. I have decided will also put a spacer (washer) between the front of the new bearing and the collet when I re-assemble, as I believe the prop driver was "binding" ever so slightly against the face of the crankcase nose when I tightened up the prop.
4. OK ... off with it's head!
I undo the 3 slot head screws with a correctly sized screwdriver. Heads on the screws do not appear to be soft, the metal must be OK. They are not really nipped up. They are almost loose, very little tension at all! They come out quickly and are only 1/4" long! Screw threads are nice. Underside of head is anodised gold and is flat as expected. There is a smear of fine debris (though not a lot) under the head. There is no gasket between head and cylinder ... none is needed as there is no seal. This is a "traditional" diesel, the contra-piston is in the cylinder. Fins are integral with the cylinder. This is unlike a large PAW. Rapid heat transfer would be a benefit
The three screw theads in the cylinder are fine. No sub-standard workmanship here. The contra-piston has a 1/4"round and 1/8" deep dimple in the middle where the bottom of compression adjusting screw faces it. The bottom of that screw is nicely rounded so as not to "chew" the contra-piston where it meets. They have a matching profile. There is not much debris on top of the contra-piston, which is only about 1/8" into the cylinder. I feel good knowing the engine has not been "fiddled with" since leaving the factory.
I clean these areas up quickly and move on
5. I find my adjustable spanner (US: shifter wrench). I tighten it carefully across the substantial flats on the top of the cylinder. A firm twist anti-clockwise and it budges, the flats are not marred. I begin to unscrew it, it is easy to do by hand. The thread is about 1/2"deep into the top of the crankcase casting, which ends where the bottom of the exhaust collector ring sits on it. Threads again seem to be nicely made, no burrs or deformities.
Cylinder with integral cooling fins comes off in my hands and I hold it, and I gently ease off the exhaust collector ring.
There is fine debris on the thread where the cylinder screws into the crankcase. A black rubber/fibre gasket sits on the bottom of the exhaust collector ring, to make a (hopefully) leak free seal. There is no gasket on top of the collector ring where it meets the bottom cooling fin? Odd. I will make a gasket, or use some hylomar or similar gasket cement when re-assembling to hopefully ensure there are no exhaust gas leaks!
There are four "slot" exhaust ports with angled exits out. The four intake channels are almost half-moon grooves milled on the lower outside of the cylinder, below and between each the ends of the exhaust slots. If you have never disassembled a traditional diesel this is a very different arrangment to a schnuerle set up. Intake holes at the top of the grooves are angled up and are 1/8" in diameter ... looking quite restrictive by today's usual standards!
There is some fine debris on the bottom of the contra-piston and a little in the cylinder, but not as much as I had feared. There is no significant scoring. I clean these items quickly.
I use an old nylon toothbrush to clean the outside of the cylinder between the cooling fins, there is a lot of debris here. Cosmetic issue only, but it should have been cleaned up at the factory.
6. Piston and conrod assembly is easily removed by a few quick taps of the back of the crankcase on the bench. The big end falls off the crankpin. Piston and conrod are removed in the usual way out the top of the case.
Piston has a reasonable surface finish. There is a little light debris under the skirt and on the crown. Some preservative staining is evident but no "goo". I was expecting to see some. Big end (bronze bushed) has no oil hole. Little end is to my mind a very loose fit on the gudgeon pin (US: wrist pin). Gudgeon pin has no circlip retainers or end pads! It is solid and the ends are slightly rounded. It is free floating. With a little effort with a pointy ended plastic biro cap I push the gudgeon pin free. The fit in the piston is adequate but quite free. There is a discernable wiggle in the conrod little end to gudgeon pin fit. I feel the little end fit is way too loose. Little end has no bronze bushing. The bore of the little end seems to have a number of micro-striations (straight little grooves across from one hole to the other) presumably to permit oil ingress for lubrication. Fascinating. Little end holes looks slightly oblong up-and-down!
This concerns me. There is real play here.
There is no obvious front or back to the conrod.
Piston is deeply skirted. The top has a smooth cast 45 degree bevel edge (about 1/16" wide) where edge of crown falls away to the side. I have not seen that before. Piston crown is flat topped. I polish it very lightly to remove some surface staining. Probably a waste of time ... it will stain with combustion by-products pretty quickly once it is fired up!
7. I point the nose of the case to the bench and tap the end of the crankshaft to try to remove it out the back of the case. No movement of crankshaft. I place case and crankshaft in the oven at 150 degrees C. for 10 minutes. I remove it and try again. Serious taps on end of crankshaft. No movement. I will think about this a little longer. I decide to entrust removal to a friend who has a way of persuading stubborn assemblies to separate without destroying them. He has a "serious" propane torch for localised heat application.
I am surprised that after the long solvent bath and heat that there is no movement. Oh well.
So, I have a final challenge so far as disassembly is concerned. I will report again in a few days.
To remove the prop driver I borrowed an O.S. puller from a mechanic mate. I will be buying one myself . I was trying to use a car battery terminal puller, but was wrestling with it to avoid gouging the nice finish on the driver. The O.S. puller fitted a treat, and the driver was off in trice without marking it's mirror finish. If you like stripping down model engines, this O.S. puller is a great piece of kit to have.
So:
1. Off with the prop driver collet ... a fairly tight fit on the shaft. A wave of the mini propane torch, it expands and with a gloved hand, it's wriggled off.
2. Front bearing is open faced. I hate open faced front bearings. I won't debate about it. Many european and former eastern block engines use them. I dislike the dribbling or spraying raw fuel syndrome you get with them. It will be replaced with a sealed bearing. I'll remove the rear seal to allow for lubrication if it is not pre-lubed for life.
3. I have decided will also put a spacer (washer) between the front of the new bearing and the collet when I re-assemble, as I believe the prop driver was "binding" ever so slightly against the face of the crankcase nose when I tightened up the prop.
4. OK ... off with it's head!
I undo the 3 slot head screws with a correctly sized screwdriver. Heads on the screws do not appear to be soft, the metal must be OK. They are not really nipped up. They are almost loose, very little tension at all! They come out quickly and are only 1/4" long! Screw threads are nice. Underside of head is anodised gold and is flat as expected. There is a smear of fine debris (though not a lot) under the head. There is no gasket between head and cylinder ... none is needed as there is no seal. This is a "traditional" diesel, the contra-piston is in the cylinder. Fins are integral with the cylinder. This is unlike a large PAW. Rapid heat transfer would be a benefit
The three screw theads in the cylinder are fine. No sub-standard workmanship here. The contra-piston has a 1/4"round and 1/8" deep dimple in the middle where the bottom of compression adjusting screw faces it. The bottom of that screw is nicely rounded so as not to "chew" the contra-piston where it meets. They have a matching profile. There is not much debris on top of the contra-piston, which is only about 1/8" into the cylinder. I feel good knowing the engine has not been "fiddled with" since leaving the factory.
I clean these areas up quickly and move on
5. I find my adjustable spanner (US: shifter wrench). I tighten it carefully across the substantial flats on the top of the cylinder. A firm twist anti-clockwise and it budges, the flats are not marred. I begin to unscrew it, it is easy to do by hand. The thread is about 1/2"deep into the top of the crankcase casting, which ends where the bottom of the exhaust collector ring sits on it. Threads again seem to be nicely made, no burrs or deformities.
Cylinder with integral cooling fins comes off in my hands and I hold it, and I gently ease off the exhaust collector ring.
There is fine debris on the thread where the cylinder screws into the crankcase. A black rubber/fibre gasket sits on the bottom of the exhaust collector ring, to make a (hopefully) leak free seal. There is no gasket on top of the collector ring where it meets the bottom cooling fin? Odd. I will make a gasket, or use some hylomar or similar gasket cement when re-assembling to hopefully ensure there are no exhaust gas leaks!
There are four "slot" exhaust ports with angled exits out. The four intake channels are almost half-moon grooves milled on the lower outside of the cylinder, below and between each the ends of the exhaust slots. If you have never disassembled a traditional diesel this is a very different arrangment to a schnuerle set up. Intake holes at the top of the grooves are angled up and are 1/8" in diameter ... looking quite restrictive by today's usual standards!
There is some fine debris on the bottom of the contra-piston and a little in the cylinder, but not as much as I had feared. There is no significant scoring. I clean these items quickly.
I use an old nylon toothbrush to clean the outside of the cylinder between the cooling fins, there is a lot of debris here. Cosmetic issue only, but it should have been cleaned up at the factory.
6. Piston and conrod assembly is easily removed by a few quick taps of the back of the crankcase on the bench. The big end falls off the crankpin. Piston and conrod are removed in the usual way out the top of the case.
Piston has a reasonable surface finish. There is a little light debris under the skirt and on the crown. Some preservative staining is evident but no "goo". I was expecting to see some. Big end (bronze bushed) has no oil hole. Little end is to my mind a very loose fit on the gudgeon pin (US: wrist pin). Gudgeon pin has no circlip retainers or end pads! It is solid and the ends are slightly rounded. It is free floating. With a little effort with a pointy ended plastic biro cap I push the gudgeon pin free. The fit in the piston is adequate but quite free. There is a discernable wiggle in the conrod little end to gudgeon pin fit. I feel the little end fit is way too loose. Little end has no bronze bushing. The bore of the little end seems to have a number of micro-striations (straight little grooves across from one hole to the other) presumably to permit oil ingress for lubrication. Fascinating. Little end holes looks slightly oblong up-and-down!
This concerns me. There is real play here.
There is no obvious front or back to the conrod.
Piston is deeply skirted. The top has a smooth cast 45 degree bevel edge (about 1/16" wide) where edge of crown falls away to the side. I have not seen that before. Piston crown is flat topped. I polish it very lightly to remove some surface staining. Probably a waste of time ... it will stain with combustion by-products pretty quickly once it is fired up!
7. I point the nose of the case to the bench and tap the end of the crankshaft to try to remove it out the back of the case. No movement of crankshaft. I place case and crankshaft in the oven at 150 degrees C. for 10 minutes. I remove it and try again. Serious taps on end of crankshaft. No movement. I will think about this a little longer. I decide to entrust removal to a friend who has a way of persuading stubborn assemblies to separate without destroying them. He has a "serious" propane torch for localised heat application.
I am surprised that after the long solvent bath and heat that there is no movement. Oh well.
So, I have a final challenge so far as disassembly is concerned. I will report again in a few days.
04-05-2008 | 06:59 PM
#20
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From: CanberraACT, AUSTRALIA
RE: Aurora K 600 R/C
I normally don't point out typos or spelling errors (people in glasshouses etc.) but "a waive of the mini propane torch" from a solicitor is pretty much unbeatable!
Good story fiery. Thanks for the effort.
Good story fiery. Thanks for the effort.
04-05-2008 | 07:29 PM
#21
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From: Hervey Bay Queensland, AUSTRALIA
RE: Aurora K 600 R/C
Oops [:'(]. Guilty as charged John. Freudian slip perhaps? Spelling (well, usage) corrected sir.
I am finding this Aurora engine intriguing. In my subjective evaluation well worth the $90- just for the "experience" alone! But it is by no means a "buy and fly" proposition. I could see how many R/C'ers would consider it junk. There is some nice workmanship in it, and there is some very, very ordinary stuff. It could, if assembled with care, and attention to fits, be an extremely competent twin ball raced traditional diesel.
It am thinking ... it would be nice to see Aurora consider an "export only" version of their line of diesel engines, assembled "clean", and made with more care for fits and tolerances. They could charge a little more for this. There is nothing fundamentally wrong with design of the engine I have. Just some poor hardware and lack of care in machining some areas. I'll expand on that last comment later.
I am finding this Aurora engine intriguing. In my subjective evaluation well worth the $90- just for the "experience" alone! But it is by no means a "buy and fly" proposition. I could see how many R/C'ers would consider it junk. There is some nice workmanship in it, and there is some very, very ordinary stuff. It could, if assembled with care, and attention to fits, be an extremely competent twin ball raced traditional diesel.
It am thinking ... it would be nice to see Aurora consider an "export only" version of their line of diesel engines, assembled "clean", and made with more care for fits and tolerances. They could charge a little more for this. There is nothing fundamentally wrong with design of the engine I have. Just some poor hardware and lack of care in machining some areas. I'll expand on that last comment later.
04-05-2008 | 08:48 PM
#22
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From: CanberraACT, AUSTRALIA
RE: Aurora K 600 R/C
Yep, it would be nice if they could get the average up a bit. I have a couple of the 1.3 KMills, one is 'okay', the other is a ripper. Both had good lives far as I know. I'd be interested to see if the Sharma engines are any better.
04-05-2008 | 08:49 PM
#23
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From: CanberraACT, AUSTRALIA
RE: Aurora K 600 R/C
ORIGINAL: fiery
Oops [:'(]. Guilty as charged John. Freudian slip perhaps? Spelling (well, usage) corrected sir.
.
.
.
Oops [:'(]. Guilty as charged John. Freudian slip perhaps? Spelling (well, usage) corrected sir.
.
.
.
The internet is heaven for pedants
04-05-2008 | 09:16 PM
#24
RE: Aurora K 600 R/C
I think I posted this before have 4 Sharmas 09,15,and a 19 rc and a 15 c/l . They appear to be knockoffs of the PAWs all mine run fine, no issues** all have been test stand run easy hand starters, and all are wearing PAW mufflers easily fitted by a little dremel work on the rear of the cooling fins. They do have a plastic body carb no air bleed,
not needed
** One of them had a very tight fit of the barrel in the carb . An E mail to Mr Sharma resulted in a new carb and a apology for the issue he even sent 3 props at no charge along with the new carb. I like the carbs better than the PAWs
the finish and fit seems as good as PAW and the contras adjust easily not super tight martin
not needed
** One of them had a very tight fit of the barrel in the carb . An E mail to Mr Sharma resulted in a new carb and a apology for the issue he even sent 3 props at no charge along with the new carb. I like the carbs better than the PAWs
the finish and fit seems as good as PAW and the contras adjust easily not super tight martin
04-29-2008 | 03:18 PM
#25
Senior Member
RE: Aurora K 600 R/C
I got an Aurora 650 off ebay. Put a CL venturi and Super Tigre NVA in it. Engine was said to have been flown a few times RC. Ran it on the bench. Second run the shaft bound up. Took it apart and found the thrust washer galling on the front of the case. The brass collet is a little too small. The cut in the collet was obviously made by hand with a hacksaw. Anyway, it worked to put a glowplug washer between the collet and the shoulder on the crankshaft. Ran a full 4 oz of fuel through in one run with no sag or loss of power. The engine is not being particularly powerful. 7800 on a Taipan 11 x 5. about the same as my Fox stunt 35 on the same prop. 6500 on a Graupner 12 x 6. the venturi hole is fairly small. I may try opening it a little as those figures are low for a diesel 40.
