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THE ASP.12 THREAD

Old 12-03-2009, 07:02 PM
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combatpigg
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Default THE ASP.12 THREAD

Well you never know what a new day will bring. A friend to us here at the forum had read some recent rumblings in another thread about this engine....whether or not it was worth hot rodding, etc. and asked me if I wanted to have a crack at a NIB .12 he picked up some time ago. I thought this would be a great project, so of course here we are now.
I tore it apart and noticed that the shaft had a slight amount of drag and a rough feel when it was turned. It turns out that the snout of the crank was jammed into the front bearing too tightly. I took some 600 grit to that part of the shaft and kept working it until it became a light press fit. Now the bottom end feels perfect.

The liner looks good, the fit with the piston gets progressively tighter at the top. The piston felt heavy to me, so I removed some material from inside and that seemed to make some difference. The rod looks pretty "chintzee", but we'll see how it goes.

I have a MAS 6x4 on it, unbalanced of course.
10% nitro 20% oil
old glow plug robbed from a .15

Oh ya, I almost forgot, I made a C/L venturi for it and am using a OS.10 needle to control a bladder tank. I also took a wild guess and shimmed the liner with a home made shim. You can trace a circle on thin brass sheet with a sharp scribe [over a cutting mat] until the scribe cuts all the way through. I then use the lip of the liner as a guide for cutting the outside diameter of the shim. I figure the factory sets the timing low to turn those 7x4 props well.

This thing runs pretty easily at 24,000. I would probably launch it at 21,000 or so on the first try.
The 6 inch prop is making plenty of thrust to power a 1/2A pylon racer pretty well. So far, so good!

The front bearing has a "slide in" fit to the case, so I need to get some Loctite and take care of that yet. I think it will be fun to see how fast this little guy can pull a plane!
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Old 12-03-2009, 09:39 PM
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ProBroJoe
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Default RE: THE ASP.12 THREAD

Very nice CP! I just reread the earlier ASP .12 thread and it seems Jeffie was able to spin his bone stock ASP .12 to 21500 on a 6 x 4, so you've already made a pretty huge improvement! How much did you shim the liner up? Did you do anything to the top end to restore squish / compression? (remove a shim, take an equal amount off the top of the liner, etc...) What happens if you shim it up another notch? How does the venturi size compare to the stock bore? Is a bladder absolutely necessary? Inquiring minds want to know...


combatpigg; (from the other thread)

If the engine responds with 24,000 or more without over-heating, I would then commit to building a speed plane for it.
Uh-huh... So whatta ya have planned for it?
Old 12-03-2009, 11:39 PM
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combatpigg
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Default RE: THE ASP.12 THREAD

Joe, those are all good questions and they deserve to be looked at.

The liner shim is .002" thick. Another liner shim could be tried...but 24,000 on the ground is getting up there. I might not look too hard for more performance until this engine has been clocked "as is" in a little racer.
Thrust HP says 90 mph and 2.2 pounds of static thrust at 24,000 with a 6x4.
The head looks like it has a shim already, but I need to peck at it some more to see if it's a mirage or not.
The stock carb has a .220" hole, this venturi is .226"...which is about the same size as the hole going through the crank.
The engine, NVA, prop and "fuel tank" weigh 5 ozs as a unit. You could run this with a hard tank and crankcase pressure, but the tank adds 2 ozs, which could be 10% of the intended models' weight.
I think a little delta would be fun to build for it, or look into adapting a 1/2A model that's already laying around here to carry this engine.
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Old 12-04-2009, 02:00 AM
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MJD
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Default RE: THE ASP.12 THREAD

Time for an SWR!

MJD
Old 12-04-2009, 02:58 AM
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combatpigg
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Default RE: THE ASP.12 THREAD

MJD, there might be a spare SWR laying around here somewhere?

It's interesting how the advertised HP rating of the OS, TT and ASP are all around .270

Thrust HP shows .545 HP for this combo. Sounds like hype to me.

I suppose there are mechanical engineers who could say what the working limits are for all these little parts. The rod in this thing doesn't look like billet, it looks like it might be forged.
Old 12-04-2009, 07:12 AM
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Default RE: THE ASP.12 THREAD

Thanks for the specifics CP. It doesn't seem like you've done anything "too radical", just basic hop-up tricks.... cool.

Running the numbers through Pe Rivers' spreadsheet shows slightly different numbers for speed and thrust, but what's interesting is the near 30% improvement in HP - a darn decent increase for just a few minutes work!

It's interesting how the advertised HP rating of the OS, TT and ASP are all around .270
...and that's exactly what the Prop-Power spreadsheet spat out! (Stock engine on bottom)

I think a little delta would be fun to build for it, or look into adapting a 1/2A model that's already laying around here to carry this engine.
So, flight report this weekend, huh?
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Old 12-04-2009, 08:07 AM
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Default RE: THE ASP.12 THREAD

I think he already planted it yesterday evening, and is busily rebuilding it for a test flight at noon.

MJD
Old 12-04-2009, 11:03 AM
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jeffie8696
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Default RE: THE ASP.12 THREAD

Ithought my ASP12 pulled my Little Extra around the sky just fine. It was still breaking in so we were running it a bit rich but even so it did a great job. I dont know if a little 6" prop would be effective on such a large plane but the 7" I was using worked well enough.
Old 12-04-2009, 11:26 AM
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combatpigg
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Default RE: THE ASP.12 THREAD

It's interesting to see the Pe Reivers calculator. There must be some practical knowledge that went into developing his system? I'm surprised that after running the numbers the screen didn't lock up with a red flag admonishment about running engines above their HP rating

I still need to come up with a plan for a speed plane.

I've got an idea for an aerobatic flying wing, but it would need a 7x3 prop and it wouldn't be real fast. If you guys remember the Pattern Bat, it was just a thick rectangular wing with an elevator / rudder hanging off the back. King of the little flat spinners. I fried a ENYA .11 on one of these whirling dervishes but got lots of use out of it. It could gain altitude in a spin and would drift with the air currents. There were reports that this plane irritated the neighbors of the club field as much as any, probably because if noise is being made that makes sense to the onlooker it seems more OK...but if the noise being made looks totally ridiculous, then this is what sets some people off.....[8D]
Old 12-04-2009, 11:51 AM
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ProBroJoe
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Default RE: THE ASP.12 THREAD

Ahhhh.... a flying wing.... now that's something I want to pick your brain over CP.... but that's another topic altogether....
Old 12-04-2009, 04:14 PM
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Default RE: THE ASP.12 THREAD

ProBroJoe-anywhere I can download PE's speadsheet from? I do note that there is a wide variation in prop constants of up to 40%-and that is often where the danger lies in simply comparing rpm figures. Torque absorption coefficients (which underpins the prop constant figure) vary widely and not infrequently-between examples of the same prop. CP-in the spirit of being conciliatory-can we agree that BHP does not fly models-thrust does-and the fastest prop on a particular engine is rarely the one producing the most thrust? Your figures show a vast increase in calculated HP for the slightly modded ASP 12-can we agree that in increasing the revs you have also moved the BHP curve up in the rpm band? [or putting it another way-on the usual graphical power plot-shifted it in both the x and y axes-upwards and to the right]
As intimated earlier in this thread, when I aroused CP 's ire-I have an as yet unrun ASP 12 that I got in the early 1990s-so it would have been a very early model. Physically it appears no different that CP's one stripped down, but I imagine they have improved their quality control over the past 20 years. Mine is stamped 91 3 737 on the engine lugs, suggesting it was probably manufactured in March 1991-and I would have purchased it in late 91 or 92. I lent it to a mate who was going to use it in the aforementioned piped 09/open exhaust 12 speed class, but he did nothing with it and eventually I retrieved it still unused.
Seeing as CP has done the slightly modded bit, I'll run my one up in std form-after I've knocked up a venturi on the lathe, and supply some bog standard engine figures. I'll stick to the 10% nitro, 20% oil fuel CP used [castor or synthetic CP?] It will be a week or two as I'm out of town for the next couple of weeks. The prop shown should be interesting............fairly new on the market-and perhaps intended for combat or pylon? I actually bought a number for F/F power duration to see how they stacked up against the APC 6.5x2.9

Returning to the HP thing-quite a few years back-early 90s IIRC-and I think it was either Model Builder or Model Aviation-a simplified formula was published that gave HP purely on the basis of prop rpm and prop dimensions. It had about 5 components-including rpm, pitch and diameter and some of these were cubed and one was to the fifth power. I used it quite extensively then, but it became apparent that it consistently gave figures above those shown in the published engine tests-and it became clear that a number of assumptions had been made in deriving it-one of which was that propellor constants did not vary significantly between brands-which simply did not appear to be justified. Another problem-and it may also apply to the PE Reivers spread sheet system-is what constitutes pitch? There is no industry standard that defines pitch on model plane propellors. We all know what it is physically-but what parameters does a manufacturer use when he calls his prop an 'A x B' prop? Average pitch? Peak pitch? Pitch at a particular radius? Constant geometrical pitch (very rarely used I might add). Measure a few props taken at random from your own stocks and you find that even diameters can vary from that stated on the prop-let alone pitch-and both these determine the load imposed by the prop and the HP required to turn it at xyz revs. Add to that blade shape, blade area and blade thickness-and you have at least 5 independent variables that characterise any particular make and brand of prop [and I haven't included rigidity or airfoil section]

ChrisM
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Old 12-04-2009, 04:38 PM
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ProBroJoe
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Default RE: THE ASP.12 THREAD

Chris,

The Prop-Power Calculator can be downloaded here:
http://mvvs.nl/prop-power-calculator.xls

The picture I attached earlier is just a screen capture of one small section of the spreadsheet - the full thing and the data encompassed in it boggles the mind!

Enjoy!

-Joe
Old 12-04-2009, 05:21 PM
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Default RE: THE ASP.12 THREAD

Thanks Joe. I look forward to having a play with it. PE Reivers frequently posts on the Everything diesel forum. I believe he is the MVVS agent for the Netherlands.

ChrisM
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Old 12-04-2009, 06:13 PM
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Default RE: THE ASP.12 THREAD

Here is the start of the frame work. It has 22" of span and measures 14" from the firewall to the hinge line. Pretty much the same proportions as the Screamin' Demon in the overhead view. The general idea is to do this with the least amount of effort, but little details like bracing the junctions where the main framing members meet need time and attention. The 2 areas where the wood meets the ends of the spar will get patches of glass cloth to tie that in good. Same goes with the 2 aft corners, they've been doweled with toothpicks and will also get extra bracing. It's a big, scary World out there to these little planes, so the leading edge is a strip of spruce. It should be able to plow into a thistle plant with a balsa strongback added.
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Old 12-04-2009, 09:16 PM
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Default RE: THE ASP.12 THREAD

Wow, I was just kidding about the weekend flight report! [X(]

Old 12-05-2009, 01:16 AM
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Default RE: THE ASP.12 THREAD


ORIGINAL: ProBroJoe

Wow, I was just kidding about the weekend flight report! [X(]

Joe, too late, you’ve already thrown the gauntlet! I’m betting on CP.
Old 12-05-2009, 02:06 AM
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combatpigg
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Default RE: THE ASP.12 THREAD

Hey AL.........you know how it is, the early progress is all eye wash. The Devil is in the details.
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Old 12-05-2009, 08:33 AM
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Default RE: THE ASP.12 THREAD

The Devil is in the details.
Yea, for most of us, but it doesn't seem to slow you down any!
Old 12-05-2009, 07:04 PM
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Default RE: THE ASP.12 THREAD

I just posted a add for a New in package Piston and sleeve for a ASP12 if anyone is interested.
Dennis
Old 12-05-2009, 07:32 PM
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Default RE: THE ASP.12 THREAD

Does the piston include a conrod? CP's gonna need one of those soon enough I bet..

MJD
Old 12-05-2009, 07:39 PM
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Default RE: THE ASP.12 THREAD

no does not come with the connecting rod
Old 12-05-2009, 08:43 PM
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Default RE: THE ASP.12 THREAD

I sold a few of these years ago while in the business. They come apart pretty quickly. I would not invest money in one, just buy a Japanese engine. Money better spent.
Old 12-05-2009, 10:48 PM
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combatpigg
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Default RE: THE ASP.12 THREAD


ORIGINAL: MJD

Does the piston include a conrod? CP's gonna need one of those soon enough I bet..

MJD

I'll bet the rod is the weak link, too. I asked a guy "in the business" a few years ago what set OS apart from the cheaper Chinese engines and he used the term "softer" for the cheaper clones. Some of these engines might have the performance potential short term, but OS will usually outlast them.
Old 12-06-2009, 03:04 AM
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Default RE: THE ASP.12 THREAD

Could you make a new rod out of some really tough material? Joe just needs one rebushed but it is for quite a bit bigger engine.j And Ineed one for my Norvel .15.
Old 12-06-2009, 03:59 AM
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combatpigg
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Default RE: THE ASP.12 THREAD

Making a high performance rod is a labor of love for the hobbyist and the investment in getting tooled up to make them could pay for a few nice engines. RPM used to be where everyone went for upgraded rods. That was 20 years ago, I don't know where to go any more. The best hope is that OS makes a direct replacement. If you can get a hold of 7075 in a T5 or T6 hardness and match up the hole sizes to standard size drill bits, you can make your own unbushed rods for .15s on down....but it's a lot of unguaranteed work for something that could be found with a little bit of luck for $5 somewhere.

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