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| Beginners / Newbies Interested in getting in the hobby. Not sure where to start. Post your questions here and one of the RCCanada experts will be glad to help you out! |
Topic Review (Newest First)
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| 07-14-2011 05:56 PM | |
| Cougar429 |
Re: Engine Orientation I have the EVO 46 mounted inverted in the Harvard II and the carb settings are close to normal now I have the tank height correct. 12 clicks must have meant you had to alter the stop collar position. |
| 07-14-2011 04:51 PM | |
| Guest |
Re: Engine Orientation Here is another issue I have found. I took the Evolution .46NX off a Porter. The engine was mounted inverted on this plane. I put the engine on a 4*40 and fired it up. I had to lean it out 12 clicks on the needle valve to make it run similar to how it ran on the Porter. Both these planes were ARFs and the centre line of the tank was within normal limits of the cetre line of the carb. Anyone else notice these significant changes when turning an engine to different orientations? |
| 05-28-2011 10:25 AM | |
| kip51035 |
Re: Engine Orientation This is the instillation on my Spit. |
| 05-27-2011 07:45 PM | |
| Guest |
Re: Engine Orientation Well the only thing left to do is maiden the Pilatis. I will make sure I have my temperature gauge handy! My co-pilot (black kitten that is out with me every time I fly) will supervise 
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| 05-26-2011 09:37 AM | |
| Cougar429 |
Re: Engine Orientation The aesthetics was why I recommended replacing that highly visible line with regular silicone. Much less of a contrast there. From the way you cut the cowl to fit the engine the air enters the cowl around the engine cooling fins on the head and cylinder bore. This is where the greatest heat is generated. The engine case is cooled by the incoming air charge and can be completely enclosed. If you have no exit for that cooling air pressure will build up till it matches or exceeds ram effect and will stagnate around the fins. This is bad as no heat transfer will occur and the motor will overheat. This will likely lead to seizure in short order. That normal 3X area rule is due to the fact heated air is larger in volume and requires a larger exit path. You MUST create an exit in your cowl or you will run into trouble. If you are concerned with cowl strength then one option is to add strengthening inside the cowl for the remaining material with fiberglass tape/epoxy or some other material to bond the glass to the cowl. As you can see in the previous pic of the motor installation in the PC9 the cheek inlet provides a good entry for the air and there is enough exit behind the motor for it to carry the heat away. I ran into the same sort of trouble with my first fully cowled engine, a Saito 91 in my Sig Skybolt. I had provided the proper amount of exit area at the back of the cowl, but with nothing to direct cooling air around the engine the air found the path of least resistance, (in this case the bottom of the crankcase) and provided no cooling. I had to come up with some way to direct that cooling air. Using the exact same technique we need on real aircraft I fabbed a barrier to direct that air only around the head. It included plates behind the opening to keep the air tight against the head fins until beyond the motor, as well as a dam at the front of the exit to create an area of low pressure. Problem solved. Here are pics of the Skybolt and Harvard with the same type of fully cowled rig. If you look at real aircraft with fully cowled radials you will frequently see a series of flaps at the rear of the cowl that can open during times of low airflow, (ground ops) to help cooling. The Corsair and B29 are good examples. For craft that found cooling problems even in flight another little bit of sorcery was the addition of what was called an "Augmentor" where a sleeve was fit around the exhaust with the inlet inside the cowl and exit outside. They had the exhaust outlet within that tube. The high velocity exhaust drew cooling air along with it and basically blew it outside the cowl. |
| 05-26-2011 09:10 AM | |
| Guest |
Re: Engine Orientation The purple line is just too long and buggers up the aesthetics. I was made aware of the venting issue, but frankly have no idea of where to cut anything else out. The won't be enough material left (at 3X the inlet) to not have it self destruct in flight. This 3X the inlet is an interesting topic. Where does/would the air bleed into the cowl? I can see some getting in at the cylinder and muffler, how about around the crankshaft? |
| 05-26-2011 08:33 AM | |
| Cougar429 |
Re: Engine Orientation Good fit with the cowl. My concern is with cooling air exit. Is that space ahead of the gear open to the engine compartment? If not you will need to look at creating an opening aft of the motor for the air to exit. The normal rule-of-thumb is for the exit to be 3X the size of the inlet. That purple line is only a problem visually. If you have the access replace it with regular silicone line and then worry about shortening it if you worry about it catching some obstruction. |
| 05-26-2011 12:09 AM | |
| Guest |
Re: Engine Orientation Well the engine end is done!  The cowl took forever. I will have to shorten the pressure line (purple one) and I really haven't had very good luck with those Red spinners. If it rains I will get this puppy buttoned up. |
| 05-25-2011 08:09 PM | |
| Cougar429 |
Re: Engine Orientation When you have access to the carb the fill/empty process involves simply unplugging the fuel line from the carb. This gives you access to the clunk line in the tank and will help when it comes time to empty since the clunk tries to reach the lowest point. When fully cowled and the line is not accessible you have a few options. One is Dubro's "Quick Fill" valve that bolts into a hole in the side of the cowl. When the insert is plugged in the line to the carb is shut off and you have a straight run into the tank. When complete popping out that insert, (that is on the end of you fuel bottle line) the tank is now connected again to the carb. On a three line rig you still have the standard vent and motor feed line with the clunk, but the third line can either be run to another clunk or set up so that somehow it will be at the lowest part of the tank. I use this method in my cowled engines and run plastic aquarium tubing since it is the correct diameter and very easy to shape with heat. I curl the line to the lower left front of the tank and since most are taildraggers simply tilt the plane onto its nose while defuelling. I never liked the second clunk due to interference with the one feeding the eingine. As for inverting an engine there should be no problems other than what I mentioned earlier with the plug and what was already covered regarding tank position and care for hydrolock. Due to their very nature they do not really know what direction they are pointed. If mounting were critical to how they run the maneuvers we do in the air would cause issues. Most of what I have seen in that regard are due to improper installation or setup, (mixture, correct plug, etc.). As I mentioned I have the Pilatus with the EVO 46 running inverted. If the tank height is correct and the rest is taken care of it honks like a scalded cat. Only things non stock are the Macs pipe and 4-stroke plug. The first pic shows the pipe, but this was one of the earlier attempts and the motor was sitting too low for the cowl. |
| 05-25-2011 07:24 PM | |
| Guest |
Re: Engine Orientation That has crossed my mind, but would make the plane look funny. The cowl has a couple intakes for the turbo (I think). John says that is one feature that identifies the Pilatis Porter PC-6. I stole the .46 Evolution off a Four Star Fourty. This plane is rated for a .46 and the motor mount fit with the usual grinding of the mount. *Evolution engines are a PITA to fit on traditional mounts*. Would running a glow plug with an "Idle Bar" help an inverted engine? |
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