Aurora Tornado .049

Yep, there's my problem. Perfectly good Tornado but the reed is gone. I was led to believe that the plastic reed was a separate item, so I went ahead and tried to remove it. Turns out it must be moulded into the alloy ring. (It was toast anyway).
I was also led to believe that I could make a new separate reed from heavy vinyl sheet. This also appears to be not quite as simple as it sounds. I made one, but it doesn't appear to work when employing the suck/blow test. I haven't tried to run it.
If anyone has a true proven method of replacing it I'd certainly be very pleased to give it a shot & get this thing going.

Rod.

Yeah, the red is the other culprit and issue me believes. I will take it apart and play with it to see what I can come up with. I like the idea of a Cox tank fitting. I honestly never thought of or tried it. Definately worth swapping a tank to for trial runs. And as for the head, thanks for the link. I did know the Cox heads did not fit, as I did try that one.... Thanks for the help. If I make any breakthroughs I will post about it. I have nothing sentimental with this engine so if it is not original, I am not at a loss.

Hello, here I leave my own video and experience modifying the glow plug.
The engine works very well!

Thank you Mauricio for the video. It and your picture are great. I like that you adapted a Cox spring to it as I did not think of trying that either.

Plus your head looks nice as well. The drill and tapping are good. Mine was very roughly done and my fins are bent and chewed up pretty good.

Further to my earlier comment regarding the Tornado 049 vs 060 heads-in the attempt to check, i had the not infrequent outcome of the whole damn 060 cylinder unscrewing rather than the head-but I did check the bore which is 11mm-compared to the 049's 10mm bore-now the heads have a shallow hemispherical profile of full bore width-much like the original Cox 350 [but if anything-shallower]-so the 060 head and 049 heads would not satisfactorily exchange-even if the threaded portion has the same diameter (which I have yet to confirm).....so it would pay to order the right head from Mecoa, should you decide to source one from there.....and that leads me to a further point-make sure you KNOW which variant you have (049 or 061)-the 049 is supposed to to have the whitish translucent tank-the 060 a red tank-but Mauricio's example shows a 'mixed' tank setup-and it is known that the factory sometimes used the 'wrong' colour-the best check is to look on the underside of the crankcase-the flat portion abutting the tank-where you will find the capacity stamped in quite small lettering along with 'Aurora' or 'K&B'....depending on the age of your particular engine.

Having just checked over and re-oiled-my three examples-two 049s, one 060-I may have one 049 with a dud reed unit as well-the others are both in excellent condition-so I may well do some comparative tests in the near future-as to the best of my knowledge-no engine test has ever been published on the 060....

ChrisM
'ffkiwi'

Thank you for the information. Mine is indeed stamped Aurora Tornado .049 on the underside. I will be disassembling it tonight to play with is and see what I can try and figure out with that reed system....

Close to 12,000 RPM on FAI (no nitro) fuel and and reduced compression glow plug head seems quite good, Mauricio. Looking at Sceptre Flight, the Tornado with its standard glow head compared favourably in HP to the Cox Golden Bee. This is not bad considering it is also a reedy.

I imagine that my OK Cub .06 reedy with glow plug head is probably on par with these engines. I don't have any RPM numbers though to give a fair assessment.

George, I was playing around with my OK .059. I assume it's the same. A Cox glow head will fit the OK and it makes a very audible difference in rpm's. The stock OK hex head adapter has a substantial hemi'd head. I believe with losing some area in addition to the glow plug as well there's quite a loss in compression. I couldn't use the stock Cox glow head without using 2 head shims due to the lower fin bottoming out on the cylinder before getting tight. It was a neat experiment.

Thanks, Ken for the bit of info. Yes, OK uses .059 and .06 interchangeably. I wasn't aware that the Cox heads could fit if shimmed. It opens new options. The OK's have the same mounting bolt pattern as the Cox tank back engines, which means they would be a good shoe in.

Ok. Time for a little update... First, I tried a Cox tank. It does fit, and holes line up, but the screws are a different thread, as they are a tiny bit larger. Secondly, and more importantly, the reed! So mine failed the suck/blow test miserably. So, I had absolutely nothing to lose. As I disassembled it I looked at the reed and saw it had a crease in it. I looked at it and saw it is definately a two piece ring. With nothing to lose, I looked carefully and saw one side of the ring was a bit taller than the other. I then placed my smallest jewlers screwdriver in teh corner and tapped it with a small rubber tipped hammer. I heard a crack, then looked carefully and saw that I split the ring in two just as planned. I then took my screwdriver and gently pryed along the edge till it was apart. The center plastic is indeed deformed. Now all I have to do is find a material that is impervious to nitro fuel, stretch it in place and hammer the ring back together and using a hole punch make the center hole. I know my dad has latex and nitrile gloves in his shop. I was thinking the nitrile would be the best option. Or does one think a part of a computer disk would be better? The factory reed is kind of an inbetween the glove and disk. So, tomorrow I will head back and grab a glove and try reassembling the reed! Be warned though, that upon disassembly, a small part of the outer edge of the ring chipped away, but if it goes back together, I do not care. And at the approximate 7 o'clock position, you can see the damage to the ring I mentioned.

The problem I foresee is that you would have to mould any replacement reed to shape-they are not a flat unit like most conventional model engine reeds.....in fact if memory serves, they were not described as 'reed' valve engines-but 'diaphragm valve' and the induction system was advertised as the 'flex-o-matic' induction system....I would be inclined to go for the mylar 'floppy disc' option personally-but in any case you need to get a micrometer on the existing reed you have 'extracted' to confirm the exact thickness of the plastic material. Teflon might also be a suitable material-but I'm unsure of whether it can be effectively moulded....it does deform and take a 'set' in thin sheet form-as evidenced by cap liners...and in our specific modelling usage-by the davis diesel 049 and 020 head seals.....

ChrisM
'ffkiwi'

Ok. I see what you are reffering to now. What I assume happens when they build these, they simply laid a flat piece over top of the ring and snapped it together, in turn forming it as seen in my picture. Well only time will tell, and if all goes well, I may be able to do a couple tests, but hopefully the first will work....

Having dug out the original 'Model Aircraft' issue (March '61) that the Sceptreflight engine test scan was taken from-I took the time to read over it in a more legible form....and noticed the valve material is mentioned as being 0.003" thick.....which will at least give you a starting point for material selection.  I was slightly in error earlier-the intake valve was described as " Flex-O-Valve" not "Flexomatic" [not that that is really here or there!]    This same test -by the renowned engine tester Peter Chinn-will also have been published in MAN a year earlier-albeit in a slightly different format to the MA one....Peter Chinn was always UK based-even though he was the engine reviewer for MAN for some two and a half decades or more.

apropos to the subject matter in hand though-I have a vague feeling that somewhere along the line I've read that the Tornado valve design was changed part way through production-and there are two distinctly different valves to be found....[not unexpected of course-Cox after all changed from the cruciform reed and 'e-clip' retainer to the rectangular reed and 'top hat' retainer during their long 049 Bee model type production -and if you go back to the very earliest Cox 049s-the Thermal Hopper and Space Bug-used a different set up yet again]

ChrisM
'ffkiwi'

NEW222 wrote:Ok. Time for a little update... First, I tried a Cox tank. It does fit, and holes line up, but the screws are a different thread, as they are a tiny bit larger. Secondly, and more importantly, the reed! So mine failed the suck/blow test miserably. So, I had absolutely nothing to lose. As I disassembled it I looked at the reed and saw it had a crease in it. I looked at it and saw it is definately a two piece ring. With nothing to lose, I looked carefully and saw one side of the ring was a bit taller than the other. I then placed my smallest jewlers screwdriver in teh corner and tapped it with a small rubber tipped hammer. I heard a crack, then looked carefully and saw that I split the ring in two just as planned. I then took my screwdriver and gently pryed along the edge till it was apart. The center plastic is indeed deformed. Now all I have to do is find a material that is impervious to nitro fuel, stretch it in place and hammer the ring back together and using a hole punch make the center hole. I know my dad has latex and nitrile gloves in his shop. I was thinking the nitrile would be the best option. Or does one think a part of a computer disk would be better? The factory reed is kind of an inbetween the glove and disk. So, tomorrow I will head back and grab a glove and try reassembling the reed! Be warned though, that upon disassembly, a small part of the outer edge of the ring chipped away, but if it goes back together, I do not care. And at the approximate 7 o'clock position, you can see the damage to the ring I mentioned.

That's interesting.  I kind-of suspected that the reed might be "sandwiched" between the two halves of the outer alloy ring.  I'll have to give separating it a shot & hopefully remain undamaged.  In order to work I believe the reed will need to be quite flexible or "stretchy".  Maybe it was Mark Boesen who originally suggested to me to use a flexible vinyl material rather than a stiff Mylar-like sheet.  Knowing that the outer edge of the reed is clamped helps my understanding of how it all works.

This certainly rekindles my interest in this engine.  Knowing which way around the reed/ring assembly goes will be important on reassembly.

When re-installing just watch the reed. It sits in place better in one direction than the other. The reed sits lower in the ring one way over the other bringing it closer to the metal spacer over the venturi.

Oldenginerod, I have a question for you..... I have to tickle your brain if I may. While disassembling the engine originally, I did not notice in which orientation the lower disk with 5 holes in it goes. Is it with the tiny center point facing up, or down if you recall. I am not asking you to go out of your way, but rather just seeing if you recall the direction. I do not think it really matters if it can pass the suck and blow test. I had a busy day today and did not have much time to play with it. But, I did get some promising results which may be good news. The bad news, however, is that I was unable to snap the ring back together..... Hopefully tomorrow I may have more time to play with it so can do some more testing. The extent of my testing till spring will be only the suck and blow test. And as I have nothing to compare it to, it has a slight 'pinch' at the top of the cylinder, but now that is the least of my problems! Thanks.

The conical section must face up, towards the engine/reed. I've never removed that part from my tank to have got it the wrong way around. The hole in the centre of the reed won't seal if the cone faces down.
Since we've been discussing this I've had another look at my original attempt to reproduce the reed. Originally it failed the suck/blow test dismally, but today, I refitted the same reed and it sealed quite well. I have just placed the reed laying directly on the alloy plate with the holes and centre cone, and placed the alloy ring which housed the original reed directly on top. I haven't refitted the retainer at this stage as it's not easy to remove. My biggest concern is that, because the reed material is rather elastic, I'm not sure the ring and retainer will clamp the outer edge of the reed adequately. It could easily be sucked out of place. I'll have a very gentle attempt at splitting the alloy ring, hopefully without damage. If it does clip together you should still be able to get yours back in one piece, unless the chipped part is too damaged.

Alright. Thanks again for all the help. Rod, teh best I had yesterday was indeed as you mentioned. I sat the ring over top of the metal disc, then used the big part of the original ring to hold it down in place. Then in turn after reading your post, I realized something. My retainer on top is very loose. The part of the tank that goes into the crankcase is indeed mushroomed out on the top, and when I go to remove the tank assembly, it is a very hard and tight fit. It really 'clicks' into place. I wonder if the previous owner 2 before me had pryed it apart. I will now be taking another look at it. I am pretty busy tonight but may play with it for a few minutes, but tomorrow is open game...

And Mark, thank you very much for the scans.

I've seen Mark's picture of the valve before but I disagree that it is a separate part to the two-piece alloy ring.  Mine was certainly originally sandwiched inbetween the two parts of the ring, as NEW222 has described with his.  Also, the article seems to agree where it states "The valve membrane is .003 in. thick, mounted in an aluminum ring.........."
This leads me to think that it was indeed assebmled as a single unit.

Oldenginerod wrote:I've seen Mark's picture of the valve before but I disagree that it is a separate part to the two-piece alloy ring.  Mine was certainly originally sandwiched inbetween the two parts of the ring, as NEW222 has described with his.  Also, the article seems to agree where it states "The valve membrane is .003 in. thick, mounted in an aluminum ring.........."
This leads me to think that it was indeed assebmled as a single unit.

this is my understanding as well-the diaphragm assembly was a single unit-and not replaceable as individual subunit components, only as a complete assembly-but that may be a factory marketing call rather than an engineering requirement

ChrisM
'ffkiwi'

Could it be that there were changes made to the engine's reed assembly over time, that might explain the differences? Back then, they were producing these, sometimes even in the thousands on a daily basis. Any time savings even in seconds per unit to reduce labour costs or errors during assembly by eliminating a couple steps would produce a complete engine quicker and at a lower cost.