SonexBuilders.net

A friend of mine is building a Xenos, and one of the things we have discussed is a method of keeping the engine warm while it is shut down when soaring. We were basically thinking along the lines of having motor driven shutters to cut off either the cooling air inlet or outlet. Have any Xenos flyers built something along these lines and if so, was it useful?

Peter

Cowl flaps have existed in airplanes since forever. I imagine it wouldn't be terribly difficult to install a hinged flap for the outlet. I would avoid adding anything at the inlets though as this would be more likely to disrupt airflow, and there's not much room in that area of the cowl.

I built a movable cowl flap using a linear actuator. Haven’t flow enough to tell if it was worth the effort

Mine is still under construction but I will be making a friction-lockable cable operated cowl flap. I plan to attach the flap to the airframe so I do not have to disconnect it to remove the cowling. I have pondered over how to reduce or shut off airflow at the inlet but that just seems too complicated whereas the exit flap seems straight forward.

The other Xenos here in Melbourne that is under construction has a lever/pushrod operated cowl flap for the radiator exhaust air. He has the Aeromomentum engine and is currently doing taxi tests but has not flown.

Rick Caldwell
Xenos 0057

Inlet flaps on a whisper motorglider https://youtu.be/N3_RgEcEvXo?t=646

racaldwell wrote:Mine is still under construction but I will be making a friction-lockable cable operated cowl flap. I plan to attach the flap to the airframe so I do not have to disconnect it to remove the cowling. I have pondered over how to reduce or shut off airflow at the inlet but that just seems too complicated whereas the exit flap seems straight forward.

The other Xenos here in Melbourne that is under construction has a lever/pushrod operated cowl flap for the radiator exhaust air. He has the Aeromomentum engine and is currently doing taxi tests but has not flown.

One Australian Sonex builder tried a cable operated cowl outlet flap but had problems with it locking when air loaded. That's obviously a problem that could be solved but he eventually just left it locked open. I would agree that shutting off the outlet seems easier. Might also be worth considering a door to stop air flow through the oil cooler. That vertically split cowling is a bit of a curse when considering adding any of these features.

I think plenty of people will be interested to see how the Aeromomentum engine performs in the Xenos.

Peter

I have Xenos SN 0001. I have done some soaring in Florida powered off. I never noticed any issue with engine temps going cold enough to be of concern for restart. I have the factory proto type with no cowl flaps or any modifications. I do keep an eye on the engine temps. and if I see them getting to low while soaring, I will probably just start the engine.