"Micromaster"-- Centerline twin using small industrial engines

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Vigilant1, Nov 13, 2018.

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  1. Mar 20, 2019 #681

    blane.c

    blane.c

    blane.c

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    I look at the 33hp vertical engine and one reason others may be using it is all the packaging (air cleaner etc.) is on top, so when you lay it on its side all the packaging is in the rear so in a way it comes streamlined, it is just the oiling you have to figure out.
     
  2. Mar 20, 2019 #682

    Vigilant1

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    I'm sure there must be a simple, obvious reason why they don't go the next step and then rotate it 180 degrees so that the crank is on top and the heads are down. Maybe the cylinder tops would fill with oil when it is stopped? I don't know anything about the oiling of these engines, but getting the crank at the top would improve ground clearance for the prop and make the cowling a lot more streamlined.

    An interesting comment B&S makes on their Vanguard marine engines:

    . Hmmm.
     
  3. Mar 20, 2019 #683

    nerobro

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    At the RPM those motors operate at, you don't need to worry to much about prop size. And if a big prop is your think get a gear, or belt reduction on there, and raise your prop that way. Running a V motor inverted has.. a long list of troublesome parts. Oil pickup is one of them, oil control when the engine is stopped, oil playing on the underside of pistons and pooling. The motors are really not very tall, as is. 14" tall, or something like that top to bottom, and only like 9" from the top of the motor to the crank centerline.

    The Davis DA-9 flew with the engine upright, with lots of prop clearance, and a slick cowl.
     
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  4. Mar 20, 2019 #684

    Vigilant1

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    Agreed, and at these HP levels a 48" prop has an acceptable disk loading for good efficiency at reasonable airspeeds. On their side (i.e. horizontal crankshaft) the 810cc engines are about 17" tall to the top of the valve covers, and the crank is only 3.88" up from the bottom. Flipping it over would yield a nicer cowling top and visibility over the nose. But . .

    Thanks That's probably what I was missing.

    The DA-9 does look good and has a slick, nice looking cowl. But it had a C-90 Continental under it. The DA-11 had the upright B&S 18 HP engine, and it had a no-so-very-slick bump on top. But, everyone flying these little industrial V-twins seems to do it this way. They see the ugly as well as I do, and they have chosen this mounting option anyway. I'd have to know an awful lot to do something different.
    Davis-DA-11.jpg
    DA-11
     
    Last edited: Mar 20, 2019
  5. Mar 20, 2019 #685

    Victor Bravo

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    The "horizontal" versions of the V-twin engines are designed to run reliably over thousands of hours in this position. It would take a really big benefit to change it from that IMHO, whether belt reduction or direct drive.

    On low drag airplanes, the smaller prop is probably a small price to pay for the reduction in weight and complexity, as has been postulated by no less then M. Colomban, the master of low powered aircraft efficiency.

    The DA-11 cowl with it's hump may seem ugly, but any question of bad-ass-ness, cool factor, or form following function can be eliminated in five seconds by looking at the photo below. That's no less than Jimmy Doolittle with the Schneider Cup winning Curtiss R3C-2.

    Ain't no airplane and nobody on this forum that can ever be in this category of coolness, nose hump or no nose hump.

    300px-Curtiss_Racer_NASA_GPN-2000-001310.jpg
     
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  6. Mar 20, 2019 #686

    blane.c

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    Reasonable cost (cheapness) being paramount among reasons to use the industrial twins, inverted ain't never going to happen.
     
  7. Mar 20, 2019 #687

    blane.c

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    Looking at the oil pickup screens between the B&S 810 Vertical (part 1017) and for an example the B&S 993 Horizontal (group 1017)/ also there seems to be a difference in the actuation of the oil pumps but the drawings are not clear enough to be certain.

    B&S 810 Vertical description.PNG B&S 810 Vertical.jpg B&S 993 Horizontal description.jpg B&S 993 Horizontal.jpg
     
  8. Mar 20, 2019 #688

    blane.c

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    Also from the 627 Horizontal the oil pump is a little clearer...er. B&S 627 Horizontal.jpg B&S 627 Horizontal description.jpg
     
  9. Mar 20, 2019 #689

    blane.c

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    I wonder if you can just swap accessory covers and a few necessary parts?
     
  10. Mar 20, 2019 #690

    blane.c

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    The shaft in group 1024 looks eccentric which would on the 810 Vertical drive the 4 lobe gear around inside the 5 lobe star, how the oil arrive and exits is unclear but apparently it is submerged in oil.

    The shaft in the 627 horizontal group 1024 looks to drive a 6 lobe gear inside a 7 point star and there is a pickup tube.
     
  11. Mar 20, 2019 #691

    Hot Wings

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    In general, no. I can't say 100% because there may be some combination I'm not aware of where it might be possible.

    Most vertical shaft engines have the oil pump inline with the camshaft and run at 1/2 crank speed. Most horizontal shaft engines have the oil pump run off the crank gear with various ratios used.

    There are YouTube videos of V-twin repair and modification.
     
  12. Mar 20, 2019 #692

    BBerson

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    Most of these engines had no oil pump in the early days. Then they put a small pump on the PTO bearing only.
    They will work with no pump, so a modified system might not be that critical.
     
  13. Mar 20, 2019 #693

    Vigilant1

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    Did they make OHC twins with no oil pump?
     
  14. Mar 20, 2019 #694

    BBerson

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    The early OHC vertical single mowers had no pump, I think.
     
  15. Mar 20, 2019 #695

    Vigilant1

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    Thanks. And I should have written "OHV" instead of "OHC."
     
  16. Mar 20, 2019 #696

    blane.c

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    Well how is the oil filter going to work without a pump? It's just going to sit there being silly isn't it? Maybe filtered oil is a good idea?
     
  17. Mar 20, 2019 #697

    Vigilant1

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    It's nice, but not strictly a requirement. Many VWs run for a long time with just oil changes every 25 hours. A bigger problem would be oil cooling without pumping oil through a heat exchanger.
    Anyway, I don't think anyone is planning to run a 25+ HP B&S engine in an airplane without an oil pump, so we can take that off the table.
     
  18. Mar 20, 2019 #698

    Victor Bravo

    Victor Bravo

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    Part of "converting" a non-aviation engine for use as an aircraft engine is making a realistic assessment of what is or is not worth the risk. Pressure fed oil is worth having, even if it costs a few dollars extra. Oil flowing through the engine in the direction it was meant to flow, is worth the extra hassle. You're already reducing 80-90% of the cost of the engine, so don't get carried away and do anything silly trying to buy an engine that is $50 or 100 cheaper.

    If the design of the Micromaster (or any other industrial engine aircraft project) simply will not allow the propeller shaft to be that low, then there are simple belt drives that can mount directly to the engine case (Para-Zoom etc. etc). Even if you don't need to reduce the propeller speed you can still raise the thrust line and have a 1:1 ratio with the propeller 8 inches higher.

    IMHO not worth inverting the engine. That is a very good recipe for many problems and a long difficult engine development program.
     
  19. Mar 20, 2019 #699

    blane.c

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    Well the little picture shows one of the verts tipped over on its side in an airplane kit, I am just curious how they did it because it is not obvious.

    SD-1 SE33 kit.jpg
     
  20. Mar 20, 2019 #700

    Vigilant1

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    Yes, the B&S 810cc vertical shaft engine is used horizontally by builders of both the SD-1 and the MC-30 Luciole. I've seen some photos/videos showing the plumbing of the external oil return lines. It seems to work well in flight. I'll see if I can find more documentation. But for now, I think we can consider it do-able and proven in flight.

    ETA: Here's a link to a video/slideshow. Be prepared to pause at 8:48, 8:49, and 9:24 to see the oil lines plumbed to new ports in the valve covers.
     
    Last edited: Mar 20, 2019

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