... they still had Cylinder recalls.nucleus said:My logic was simple: Germans make better stuff! So I went with Thielert-owned Superior Air Parts engine. Thierlert also did most of the design work for for their roller lifters, etc.
Hans
My partner and I are looking at a RV with a 0-360 that has a counter weighted crank. We were both impressed with how smooth and quiet the plane was. We'll be using the plane for mostly for x-country so we'd like that feature. Are there any other down sides to flying with a counter weighted crank? What happens exactly when they get 'de-tuned'? And I assume it takes a re-build to 're-tune'?gmcjetpilot said:All the angle valve 360's or 390 200/210HP are counter weight cranks. So if you want non-counter weight than you will be looking at a parrellel valve 180Hp engine. Non-counter weight is a good choice if you want to save weight and are going to do formation flying (rapid throttle movements which can de-tune counter weights)...
nucleus said:My logic was simple: Germans make better stuff! So I went with Thielert-owned Superior Air Parts engine. Thierlert also did most of the design work for for their roller lifters, etc.
Hans
Low n Slow said:My partner and I are looking at a RV with a 0-360 that has a counter weighted crank. We were both impressed with how smooth and quiet the plane was. We'll be using the plane for mostly for x-country so we'd like that feature. Are there any other down sides to flying with a counter weighted crank? What happens exactly when they get 'de-tuned'? And I assume it takes a re-build to 're-tune'?
Thanks Dan! How easily can they be de-tuned, one rapid throttle movement, or hundreds? Can they be de-tuned any other way, besides abusing the throttle? How can you tell when it's happened, just a general increase in vibration?DanH said:<<What happens exactly when they get 'de-tuned'?>>
Both the crank and the weight have two sets of hollow bushings with precise internal diameters. Rollers with precise external diameters pass through the bushings. The weight thus hangs on the rollers. The rollers ("pins") are not tight fits in the bushings; they have significant clearance, which is why the pins roll when the weight rocks side to side. The clearance is the mechanical equal to a short pendulum arm. The tuned order is dependent on the precise length of that pendulum arm dimension, and the ability of the pin to roll in the bushings. The pendumum is thus detuned by wear that changes the precise relative dimensions, or by damage that disrupts the ability of the pin to roll in the bushings.
<<And I assume it takes a re-build to 're-tune'?>>
Yes, bushing and pin replacements.
Low n Slow said:Thanks Dan! How easily can they be de-tuned, one rapid throttle movement, or hundreds? Can they be de-tuned any other way, besides abusing the throttle? How can you tell when it's happened, just a general increase in vibration?
Thanks AJ!
rv969wf said:I have no idea what crank Superior is using in the XP-400. I guess a phone call to them might answer the question. I'm like you Dan, it'd be nice to know what parts / crank they're putting in those monsters.
I called Superior yesterday and asked: the XP-400 uses a counterweighted crank. It's not in production yet, as you probably know. This summer, they said.
Another fact: I was told the XP-400 uses a front governor mount. Do any of you know if it'll fit under an RV cowl?
Regards,
Martin
Non-counter weight is a good choice if you want to save weight and are going to do formation flying (rapid throttle movements which can de-tune counter weights).