The 24 year itch
11-10-2014, 04:51 AM
#51
I used the sand a groove in the foam and then epoxy method. I glued a strip of sandpaper on the edge of a piece of wood slightly wider than the carbon strip. I masked off the foam and sanded the strip on the wing until the carbon was just below the surface. Once it was epoxied in I used some model magic or similar filler to fill it all and carefully sanded it down. Smooth, stiff and light wing.
11-10-2014, 05:44 AM
#52
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Thanks for the great report.!
Knowing what you did to achieve the RTF weight really helps if I try another build of this design.
How did you attach the carbon strips [ribbon?] to the foam...?
I've heard of this method where you sand a shallow rut into the foam to accomodate the thickness of the carbon ribbon. The ribbon is sold in .005" thick rolls, IIRC.
The wood spar I put in this wing added noticeable weight. I used Elmers glue and I've got to say that plain old Elmers dries fast and has been a pleasure to work with. Hopefully this glue will perform just as well once the plane has a few hours under it's belt.
Knowing what you did to achieve the RTF weight really helps if I try another build of this design.
How did you attach the carbon strips [ribbon?] to the foam...?
I've heard of this method where you sand a shallow rut into the foam to accomodate the thickness of the carbon ribbon. The ribbon is sold in .005" thick rolls, IIRC.
The wood spar I put in this wing added noticeable weight. I used Elmers glue and I've got to say that plain old Elmers dries fast and has been a pleasure to work with. Hopefully this glue will perform just as well once the plane has a few hours under it's belt.
11-10-2014, 05:58 AM
#53
Maybe I will patch my wing up with some carbon fiber. I had a bad launch with my Simple 400, and the wing separated a bit. Fuse too. I used to have some coarse weave cloth that we would shred for making props. That should do the trick. I guess they are short lived planes?
11-10-2014, 11:29 AM
#54
Thanks for weighing in with your carbon strip experience guys..!
This wing has a little polyhedral and I wonder how effective placing flat strips on the dihedral section would be..? It seems like you would still want a vertical stiffener to run through that area, then cap it with the carbon tape to form an I beam until you get at least a few inches past the dihedral break...?
This wing has a little polyhedral and I wonder how effective placing flat strips on the dihedral section would be..? It seems like you would still want a vertical stiffener to run through that area, then cap it with the carbon tape to form an I beam until you get at least a few inches past the dihedral break...?
11-10-2014, 03:02 PM
#55
All my Mach None, or Pacer wings were dead flat on the top. Wings were three piece. Straight centre section with tapered ACE foam outers. Trailing edge is a dead straight line. This means the leading edge is swept back from the joint. Glued together upside down to keep top dead flat. No dihedral at all except that created by the taper of the tapered foam wing sections. So carbon and epoxy was not an issue as it was only in tension. No peel action unlike a polyhedral wing.
You could make the centre section any length. If you wanted 42" or 45" span just cut up the straight section ACE foam wing longer. Easy way to get more wing area. It does increase the polar moment of inertia of the wings with the long span. Slows down rolls.
I also increased the tail fin area and changed the shape to make the fin areas more symmetrical above and below the horizontal centre line.
You could make the centre section any length. If you wanted 42" or 45" span just cut up the straight section ACE foam wing longer. Easy way to get more wing area. It does increase the polar moment of inertia of the wings with the long span. Slows down rolls.
I also increased the tail fin area and changed the shape to make the fin areas more symmetrical above and below the horizontal centre line.
11-20-2014, 05:21 PM
#57
Creeping forward with cowl work.
I want flush fitting cowls, instead of the more simple "overlay" type for these 2 planes.
So, this means that the foam "plugs" need to be under cut to allow for the thickness of the cowl. Ideally, a 1/16" thick wall on cowls this size would be heavy enough to put up with typical rough handling. The reality of under cutting the foam "plug" by eye is that there wont be a perfectly consistent wall thickness so I try to err on the heavy side. I've never had a cowl turn out so heavy that it spoiled the project [but there's a first time for everything].
After sanding the foam plug to size I cover it with small strips of packing tape. This allows the fiber glass cowl to separate from the plug fairly cleanly.
The weight of most of the cloth used here is 1.5 to 2 oz. I used a layer or two of 6 oz cloth for the .15 sized cowl because that cowl will be thicker than the .049 cowl.
You must use a resin that sands well and I used West Systems here. I've used polyester resin also, but prefer this epoxy resin. It's also been sitting around for 3 or 4 years and it needs to be used up.
I want flush fitting cowls, instead of the more simple "overlay" type for these 2 planes.
So, this means that the foam "plugs" need to be under cut to allow for the thickness of the cowl. Ideally, a 1/16" thick wall on cowls this size would be heavy enough to put up with typical rough handling. The reality of under cutting the foam "plug" by eye is that there wont be a perfectly consistent wall thickness so I try to err on the heavy side. I've never had a cowl turn out so heavy that it spoiled the project [but there's a first time for everything].
After sanding the foam plug to size I cover it with small strips of packing tape. This allows the fiber glass cowl to separate from the plug fairly cleanly.
The weight of most of the cloth used here is 1.5 to 2 oz. I used a layer or two of 6 oz cloth for the .15 sized cowl because that cowl will be thicker than the .049 cowl.
You must use a resin that sands well and I used West Systems here. I've used polyester resin also, but prefer this epoxy resin. It's also been sitting around for 3 or 4 years and it needs to be used up.
12-09-2014, 10:48 PM
#58
The piston and liner are gouged in several spots, mainly along the wrist pin path on both sides. The head is really pitted. I do not recall ever eating a plug filament. Even though it's ugly, it still holds air since none of the gouges run all the way to any openings, ports, etc. It's miraculous.
I used a Cox .049 needle assy that press fit onto an aluminum nipple that is cross drilled to line up with the discharge hole in the Cox NVA. The nipple is also long enough to press into an aluminum bracket that I "milled" on my poor drill press. The press fits have been tight enough to be water tight on others I've made like this. I got the basic idea for this from Henry Nelson.
I think the ASP .12 is worth fussing with, so the night of December 9 was dedicated to this little $29.95 engine.
12-10-2014, 06:06 AM
#59
https://www.youtube.com/watch?v=Uh5Inl6hzYE
22.5K in the hand 26.8k best in the air 4P / 101.52 mph Max Theoretical
most 25.6k ish 97 mph. watched it a few times was in a rush off to work looking good CP!!!!!
Looks like it was a tad breezy that day so into the wind was scrubbing off speed.
most 25.6k ish 97 mph. watched it a few times was in a rush off to work looking good CP!!!!!
Looks like it was a tad breezy that day so into the wind was scrubbing off speed.
Last edited by Pond Skipper; 12-10-2014 at 06:09 AM.
12-10-2014, 06:12 AM
#60
Those little ASPs are a pretty good bang for the buck. I have been fiddling with the AP .15 (really a .135) and it is pretty good for testing new ideas with little consequence. It is really the same design as your .12 with the bypass ports milled in the liner, and is a rear exhaust. I made a turbo plug head, and venturi similar to yours. The ASP .15 with the blue head is very strong already, and responded better to a turbo head. Of course it is another $15. Kind of blows the budget :-) I got some pretty good numbers that compared well to the Fora even. The revs have to be kept down because of the materials used in the rod, maybe less than 22,000. Nice needle valve setup. Got some old pics here. .15 in the plane with stock head, .09 header (same block as the .15) and ASP .15 with turbo head. (stock head is blue, they are both hard on plugs)
Last edited by aspeed; 12-10-2014 at 06:41 AM.
12-10-2014, 07:46 AM
#61
Pond Skipper, the 6 x 4 seems to be a good all around choice but the prop this engine likes for speed is the 5 x 5 APC E.
This particular engine isn't as strong as a friend's ASP .12. The parts fits just aren't quite as good and it really shows...his engine's lower end has less drag. Sometimes they loosen up on their own, but sometimes you can do a complete tear down and see that either the crank is too tight in the inner races or the outer races are getting squeezed too tight. The looser the fit in the case, the better.
Aspeed, I'm glad to hear you are getting good performance out of your APs. The APs were the only cheap engine I saw marketed because I just do business with Tower. The only APs I bought were the .061s.
Your turbo head work looks great, what do you use to cut the chamber..?
This particular engine isn't as strong as a friend's ASP .12. The parts fits just aren't quite as good and it really shows...his engine's lower end has less drag. Sometimes they loosen up on their own, but sometimes you can do a complete tear down and see that either the crank is too tight in the inner races or the outer races are getting squeezed too tight. The looser the fit in the case, the better.
Aspeed, I'm glad to hear you are getting good performance out of your APs. The APs were the only cheap engine I saw marketed because I just do business with Tower. The only APs I bought were the .061s.
Your turbo head work looks great, what do you use to cut the chamber..?
12-10-2014, 08:02 AM
#62
Yes, the ASP .12 are a little "varying" in their performance...
I recently took my best (and oldest) runner apart to try to see what makes it "better". Apart from being well used, with well run ballbearings, I also found a machining flaw in the exhaust port. Turns out that part of the exhaust port has been grounded a little higher, thus making it a little "hotter" timed than the others. The effect on the ground is not that big, but it unloads better in the air. Makes one wonder what can be done by working a little on the exhaust port...
I have since then also tried with a shim under the cylinder, replacing the extra one I had under the head, this gave me an additional 300-400rpm on the top (during ground testing on a 7x4 prop). So there is certainly room for fiddling and improvements....
I recently took my best (and oldest) runner apart to try to see what makes it "better". Apart from being well used, with well run ballbearings, I also found a machining flaw in the exhaust port. Turns out that part of the exhaust port has been grounded a little higher, thus making it a little "hotter" timed than the others. The effect on the ground is not that big, but it unloads better in the air. Makes one wonder what can be done by working a little on the exhaust port...
I have since then also tried with a shim under the cylinder, replacing the extra one I had under the head, this gave me an additional 300-400rpm on the top (during ground testing on a 7x4 prop). So there is certainly room for fiddling and improvements....
Last edited by Mr Cox; 12-10-2014 at 08:04 AM.
12-10-2014, 08:21 AM
#63
Yes Mr. Cox, I raised the liner on the friend's engine and saw some improvement too.
I think I also ground the liner to match the top of the exhaust port in the crankcase.
Hopefully there is still enough demand to keep these engines around for years to come.
I think I also ground the liner to match the top of the exhaust port in the crankcase.
Hopefully there is still enough demand to keep these engines around for years to come.
12-10-2014, 12:41 PM
#64
I bought a pipe adapter for my AP .09 (MAC .09 -.15 pipe has not be cut down yet still stock may not need much in lieu of no header) also note the other pic one of the members here used a OS 4 Cyl. pipe as a muffler found it breaths more rpm.
Last edited by Pond Skipper; 12-10-2014 at 12:47 PM.
12-10-2014, 02:04 PM
#65
You can see the outlet nipple on the stock muffler in the pic. That helped the .15 quite a bit. 13,300 stock up to 15,500. Open exh was 15,700, and with a bigger control line venturi @ .240" 17,200. It will not run without pressure opened up that much. The hole in the front of the muffler I opened a bit, and the outlet I went to 6 mm because that is what the F2D guys use as a standard. I guess I could use a 4 mm venturi and a shutoff and get embarrassed in the combat circle. I have shown these pics a few places before, but for the head shape I used an old broken center drill that was 7/16" diameter and radiused it on the end to match the T Tiger .07. It is fairly close to what I wanted here. I think I may have made the bowl a bit larger so the squish band 'looked about right' The lathe has an adjustable crossfeed. The depth of the bowl is about .100" to the bottom of the plug. (an .049" is about .060" and a 90 degree or 100 degree countersink works good) You may also notice the small center drill is used for the 60 degree taper for the bottom of the thread for the seal. I drilled through at .187" and then used the center drill to open up the diameter to 7mm and the right depth. I also turned a .500" step on the outside to grab on with a collet for doing the other side on the next operation which was the bowl. I roughed out a bunch of various size stock for different size motors with just the turbo plug thread, and then did the other end as needed for each motor. This was a very high tech lathe when it was first made. That was before I was born, and I am not young.
Last edited by aspeed; 12-10-2014 at 02:17 PM.
12-10-2014, 02:55 PM
#67
Aspeed, thanks for the look at your cutting tool. I am thinking about making some heads for nelson plugs
I think I could grind a smooth radius on a drill bit while it is turning
Pond Skipper...I'm amazed that MAC has a pipe assy for that engine..! That's really good to know.
Last edited by combatpigg; 12-10-2014 at 02:58 PM.
12-10-2014, 03:53 PM
#68
I think you would be better to freehand the drill that you are sharpening, or just use a 90 degree countersink maybe. There needs to be some back clearance on a drill. It will chatter like crazy too, probably. A countersink, maybe a bit deeper than .100" to start may be a good starting point. I had trouble finding a reasonably priced 11/32" - 32 tap. for the Nelson plug, and the Turbo is a bit smaller in diameter for a better chamber shape on the little motors. The smallest motors make the biggest difference in the tapered plugs. Up to about .21 from what I found. There is also more heat ranges to choose from. Having said that, Merlin makes both for $5. That is what I use. I think the Nelson seat angle must be 120 degrees, or 30 depending on which way you look at it. Henry used to sell blanks with the thread in already, pretty much like I did. I got a couple from him many years ago before he retired. Yaro is out of taps for a while now. $25. http://aerohobby.ca/store/index.php?...roducts_id=212
Last edited by aspeed; 12-10-2014 at 03:57 PM.
12-10-2014, 04:12 PM
#69
I wouldn't mind paying $25 for a special tap.
I've read that you do not want the seat angles to match perfectly with tapered plumbing fittings in general. The idea is to deform the female side of the union slightly.
Thanks for reminding me about back clearance on the drill bit, that makes perfect sense. I'll experiment on scrap until I come up with a good bowl cutter.
I've read that you do not want the seat angles to match perfectly with tapered plumbing fittings in general. The idea is to deform the female side of the union slightly.
Thanks for reminding me about back clearance on the drill bit, that makes perfect sense. I'll experiment on scrap until I come up with a good bowl cutter.
12-10-2014, 05:39 PM
#70
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That's the 1110 pipe.? I used one on my OPS .15 RC. It is side exhaust with a short header, a few 1/8" cuts - forget how many - and I had it set up for 24k on a cut down flight prop. (5.4x5.5 trimmed from Graupner speed 6x5.5). So in flight it was running about 24k unloaded. Lovely combo on the proto 26" Demon, which met an early demise at the mercy of a panicked pilot.
12-10-2014, 05:52 PM
#71
Here is what I picked up..NEW Macs Tuned Pipe .10-.15/2.5cc Stock No. 1110
http://www.ebay.com/itm/NEW-Macs-Tun...4#ht_632wt_763
http://www.ebay.com/itm/NEW-Macs-Tun...4#ht_632wt_763
Last edited by Pond Skipper; 12-10-2014 at 05:55 PM.
12-10-2014, 08:08 PM
#73
Yes, the ASP .12 are a little "varying" in their performance...
I recently took my best (and oldest) runner apart to try to see what makes it "better". Apart from being well used, with well run ballbearings, I also found a machining flaw in the exhaust port. Turns out that part of the exhaust port has been grounded a little higher, thus making it a little "hotter" timed than the others. The effect on the ground is not that big, but it unloads better in the air. Makes one wonder what can be done by working a little on the exhaust port....
I recently took my best (and oldest) runner apart to try to see what makes it "better". Apart from being well used, with well run ballbearings, I also found a machining flaw in the exhaust port. Turns out that part of the exhaust port has been grounded a little higher, thus making it a little "hotter" timed than the others. The effect on the ground is not that big, but it unloads better in the air. Makes one wonder what can be done by working a little on the exhaust port....
[Does "Go Ape" make any sense on your translator...?]
12-10-2014, 11:55 PM
#74
No, google translate gives nothing on that, but I can guess what it means... 
The makers of the Parra engines have Nelson blanks listed/shown on their site; http://www.clubtamaran.com/Bujias.htm
Merlin also makes a few different Nelson plugs, including a Glow bee style filament. I have a few of these that I intended to test together with a Galbreath head (on Norvel .061), but I haven't gotten around to that yet. They also do Turbo plugs with the Glow bee filament, something I will try on the few Turbo conversions that I made (TT07, and VA .049).
The Macs pipe is a little short ( < 8") to use directly on an engine but with their header it all fits directly onto the ASP .12 (and OS .10 etc). One needs to change the exhaust timing though to get any advantage from them (as I'm sure you know CP). Justengines have a lot of parts listed on their website, but I don't know if they stock them all; http://www.justengines.co.uk/acatalo..._Spares_1.html
£13 for a piston and liner is a fairly good price though.
The header can also be used with an after muffler instead of a pipe. One can then get very close to the open exhaust values but without the all the noise. That worked very well on the OS.10 with an after muffler from Merker. But that's for sport flying, which is a very different topic...
The makers of the Parra engines have Nelson blanks listed/shown on their site; http://www.clubtamaran.com/Bujias.htm
Merlin also makes a few different Nelson plugs, including a Glow bee style filament. I have a few of these that I intended to test together with a Galbreath head (on Norvel .061), but I haven't gotten around to that yet. They also do Turbo plugs with the Glow bee filament, something I will try on the few Turbo conversions that I made (TT07, and VA .049).
The Macs pipe is a little short ( < 8") to use directly on an engine but with their header it all fits directly onto the ASP .12 (and OS .10 etc). One needs to change the exhaust timing though to get any advantage from them (as I'm sure you know CP). Justengines have a lot of parts listed on their website, but I don't know if they stock them all; http://www.justengines.co.uk/acatalo..._Spares_1.html
£13 for a piston and liner is a fairly good price though.
The header can also be used with an after muffler instead of a pipe. One can then get very close to the open exhaust values but without the all the noise. That worked very well on the OS.10 with an after muffler from Merker. But that's for sport flying, which is a very different topic...
Last edited by Mr Cox; 12-10-2014 at 11:59 PM.
12-11-2014, 01:41 AM
#75
Mr Cox, some how I knew that you would figure out what I meant by "Going Ape"
Is there an equivalent expression in your country...?
Thank you for the link to Parra engines and Nelson blanks.
If I could remember who I bought this $30 ASP engine from, that is still the best way to get spare parts I think. Just keep buying complete engines until you find a good one.
Is there an equivalent expression in your country...?
Thank you for the link to Parra engines and Nelson blanks.
If I could remember who I bought this $30 ASP engine from, that is still the best way to get spare parts I think. Just keep buying complete engines until you find a good one.