B&S 49-series (810cm3/49ci) for aircraft use - TiPi's Q&A thread

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TiPi

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The fact that the engine will fit inside the firewall outline and the higher prop axis were the drivers for going the (more complicated) heads-down way.
For the fins, I'm doing what I can with my equipment, so welding is not on the radar at the moment. The rubber solution from rmeyers probably wouldn't change much as the rubber still needs to go at least 5-6mm (1/4") over the fin end to stay put and do its job (the remaining little connectors are only 3-4mm deep and I wouldn't cut the larger arches). The passages are much better aerodynamically now so I'll give it a try. Its only 6 months till we have 35+ temps (C) again to really check it out.

The intake flanges might be from SS for the final version, so that I can get the pipe welded on. The trial version will be a good helping of "metal" epoxy.

I'm tossing up a bed mount (using the 2 bottom OEM mounts and 2 of the bottom cover bolts as through-bolts), a cross mount (2 bottom OEM mounts and 2 top cover bolts) or a reverse "dyno-focal" mount. Another option could be an inverter bed mount eg the engine hanging on a bed mount (using the top OEM mounts and 2 top cover bolts). I'm waiting on a couple of drawings from Spacek for the standard installation of the SE-33 engine to work out my approx engine placement.
 

karmarepair

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A note on sourcing: even though it might cost me a little coin, I always try my local sources FIRST before shopping online. So I strolled into my local power equipment dealer last week. This immigrant family deals in Husqvarna, Honda, Briggs, and Kawasaki, and will work on ANYTHING, but they told me for big stuff like complete engines, short blocks, etc, I may as well go online, as they do the same. They keep the lights on selling new equipment and on the LABOR to keep stuff running.
 

Vigilant1

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A note on sourcing: even though it might cost me a little coin, I always try my local sources FIRST before shopping online. So I strolled into my local power equipment dealer last week. This immigrant family deals in Husqvarna, Honda, Briggs, and Kawasaki, and will work on ANYTHING . . . They keep the lights on selling new equipment and on the LABOR to keep stuff running.
Not to derail Tipi's thread, but one nice aspect of the industrial engine aero conversion idea is that there are still a lot of local shops that work on these little engines. I have a suspicion that it won't be hard to find a real "motorhead" in many of these shops who would enjoy doing precise work on a clean engine brought in by a customer, maybe on a small engine stand, etc. (80 lb engine, so not very hard to lug around). If you find the right guy/gal, you'd have a valuable local partner with the right tools and experience to handle the tasks that might be more than a typical (modern) homebuilder is comfortable with. To make this work, it would be very useful to have a comprehensive but concise guide/reference material for the aero conversion stuff (as we have for the VW Type 1 in the Great Plains aero conversion guide. That book would be a good template). Mount a test "club" with drag similar to your chosen prop on the hub and he/she could even test run it to check things out.
Any paperwork/receipts could specify that it is your airboat engine, to keep everyone happy.
 
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pictsidhe

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One way to deal with fin ringing is to drill and tap, then screw aluminium rod in. Minimal airflow restriction, but good bracing. May need to make the threaded rod from welding rod.
 

Vigilant1

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One way to deal with fin ringing is to drill and tap, then screw aluminium rod in. Minimal airflow restriction, but good bracing. May need to make the threaded rod from welding rod.
And, where practical/needed, the end(s) of the threaded rod could be bent outward to provide a handy threaded stud for attachment of the baffling. It might look and work nice.
 

blane.c

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A question I have that if already answered perhaps could be indulged is in tractor configuration from the vantage of sitting in the pilots seat which direction is your propeller going to turn?
 

Vigilant1

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A question I have that if already answered perhaps could be indulged is in tractor configuration from the vantage of sitting in the pilots seat which direction is your propeller going to turn?
Here's a picture of an SD-1 with the 49-series engine driving a prop from the flywheel end.
upload_2019-10-4_12-7-26.jpeg


Given the prop pitch, it is turning CCW as viewed from the cockpit. If we turn the engine around so the PTO is in front (as TiPi plans to do), the engine would be turning the opposite way, CW as viewed from the cockpit, just like the Lycomings, etc.
FWIW, the VW Type 1s turn CCW as viewed from the cockpit. I was happy to find that it took me no time at all to get used to pressing on the other rudder pedal. Everyone I've met who flies them says the same thing.
 
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TiPi

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yep, the engine will be turning CW in tractor with the prop on the PTO end. Standard direction of rotation for all industrial engines.
The intake through the sump would be difficult to achieve without a casting or extensive sheet fabrication (think vibration and heat expansion). My current plan is to use the oil cooler heat as warm air supply, possibly connected to the throttle or by vacuum (cold air only at WOT, all other times pre-warmed).
One of the SD-1 builders experienced an engine stop from carb icing in Scotland. He was low (500') after a low pass, turning final on a wide base. About 19s from intial "rough running" to touch-down in a field. No damage other than some spots in the undies :)
He has now installed 2 small electric heating elements below the throttle plates for the landing phase.
 

blane.c

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Carb ice has damaged untold amounts of airplanes and injured and killed many people often unreported because the evidence has evaporated before post accident inspection.

But that was not the main reason I mentioned the fuel system heating, I mention it because heating the fuel/air aids in dispersion and is more efficient, that is the engine will run better ice or no ice if the fuel/air is at a proper temperature when mixing.

The Idea Pop's has is that warm oil goes into a separate small oil box surrounding an appropriate location of the induction system with "inny" and a "outy" oil lines to it. Basically a simple oil cooler with one large hole in the middle instead of multiple small tubes and no fins.
 

BBerson

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Maybe the carb heat should be half on normally all the time. The pilot could "override" this carb heat momentarily for takeoff with a spring loaded gate valve that snaps back to normal.
 

blane.c

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Ahhhhg! Maybe. ... This is TiPi's thread, I enjoy it. I enjoy it very much. Maybe start a thread on carb heat and stuff so not to ruin his thread?
 

Vigilant1

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That's one problem with living in Australia. You go to bed and all is right with the world. You wake up to find the Yanks have crashed the stock market, finished a war, entered a war, and derailed your very nice B&S question thread.😉

TiPi, thanks for the videos in the build thread. Handy comparison between the Harbor Freight, Kohler, and Vanguard small horizontal twins. The Vanguard promo film on the building of their twins was very informative. I'm surprised the castings are done there at the same facility. Very automated.
I hope your move goes well. They are never fun.
 
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blane.c

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I hope your move goes well too. You may be making exciting new discoveries when you empty the shop and pack ... if your move goes like my last one.
 

BJC

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I hope your move goes well too. You may be making exciting new discoveries when you empty the shop and pack ... if your move goes like my last one.
I have several duplicate tools / workshop items due to my last (retirement) relocation. Buying a duplicate was the only way that I could find the one that I had so carefully packed and moved.


BJC
 

Vigilant1

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Okay, since we are already derailed, no harm done to say:
- Silicone induction runs would make things simple, esp during testing.
- Something like that port hardware but for a fuel injector would be handy.
- Silicone insulates better than aluminum. The fuel/air charge is cooler than ambient air, we've already got a potential problem with fuel vapor/atomized suspended droplets condensing before being inducted, collecting on runner walls, etc. On this issue, silicone is more problematic than metal, since the interior walls of the silicone runners will be cooler than ones made of material with better heat conductivity.
 

blane.c

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There is an "oil heated intake" page.

 

Vigilant1

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Are we trying to have an oil leak?😉
If induction charge temps/condensation becomes an issue, a simple oil box might work fine. It has the advantage of directly heating the carb body, where icing often starts. Simpler and safer is the trick of tapping some small dia tubing into the exhaust and winding and winding it around the AL induction runners. Free heat, won't risk an oil leak.
TiPi's very short runs from carb to head mean probably fewer condensation problems than some other setups.
 
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