I realize this may be a dumb question, but I've never seen it discussed. Was just researching the GP Venus (although there are plenty of similar planes in this configuration). I'm used to the typical trainer setup where the engine is upright, the glow plug is easy to access, and there's no cowl in the way to hinder needle adjustments. Can someone please explain how the engine is started when it's inverted, and how do you adjust the idle once you have it running?

Thanks!

You start and make adjustments almost the same way as if the engine were not inverted. One difference should be that you turn the prop through a few rotations before applying the starter to make sure that there is not so much fuel in the engine that a "hydraulic lock" might occur which could result in a bent connecting rod. As for adjustments, the needle valve should still be easily accessable only on the other side of the fuselage. With some in-cowl engines you might need to put an extension on the needle valve so that you can adjust the mixture.

I definately find it more difficult to flip start inverted engines. However, they start easily with an electric starter.

If you know what your doing when you install the engine and fuel system inverting an engine may make no difference in its operation. Worst case is you may need a remote glow driver to achieve a reliable idle

Still wondering how you fit the glow igniter on the plug to start it in the first place...start the plane upside down in a cradle or something? Keep in mind that I've always used a wired igniter connected to my flight box...do I need to switch to a NiCd unit?

If your glow plug is hard to reach you can install a remote glow fixture on to which you can connect your glow driver whether its one hooked to your power panel or not. Check out, for instance, Sullivan products since they have a remote glow fixture in their product line. In my newest plane the engine is inverted and totally enclosed by the cowl making such a fixture a required item. Even though its beyond the scope of your questions, also note that with an inverted engine the height of the fuel tank is more critical for good engine operation, and also to avoid siphoning, than would otherwise be the case.

>>>Can someone please explain how the engine is started when it's inverted, and how do you adjust the idle once you have it running?


The same way as usual, connect the glowplug (most connectors work just as good upside down) and flip the prop it with a stick (I hate e-starters).

Just be carefull not to "drown" the engine (is that an English expression??) I mean make sure you don't get to much fuel in it since it will accumulate in the cylinder, on top of the glowplug, and it cant escape.

To much fuel could cause the glowplug to cool down, making it harder to start. Even more fuel in the cilinder in combination with an electric starter can cause serious damage to your engine.

If I really really really need the starter (almost never) , I put the plane on a wingtip (you might need a helper) so the exhaust points down, allowing fuel to leave the engine. This orientation also seems the best way to start a hot engine.


Don't worry to much about it, once the engine runs, it runs just as good inverted as it does in the normal orientation.

Hope this helps

Mostly I use a starting cradle. I turn the plane upside down in the cradle to start the plane. A remote glow adapter works well also. I have used one before. I adjust the engine with the cowl off untill it is right. I then install the cowl. After this I do not have to adjust the engine much. I put a small hole in the cowl above the needle. I cut a slot in the needle with a dremmel tool. I make any adjustments with a jewler's screwdriver. A little more hassle, but not bad.

Mark Shuman