---------------------------------------------------------- RV10-List Digest Archive --- Total Messages Posted Mon 01/24/05: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:00 AM - Damaged Prop? (LessDragProd@aol.com) 2. 08:33 AM - Lycoming - tractor engine or turbine smooth? (LessDragProd@aol.com) 3. 08:37 AM - Re: Damaged Prop? (AI Nut) 4. 08:41 AM - Re: Lycoming - tractor engine or turbine smooth? (AI Nut) ________________________________ Message 1 _____________________________________ Time: 08:00:14 AM PST US From: LessDragProd@aol.com Subject: RV10-List: Damaged Prop? --> RV10-List message posted by: LessDragProd@aol.com What do you do if you damage a prop? Ask for help. I was flying back from Van's Fly-In a couple years ago with another RV-3. When we landed at the first stop, the other RV-3 made a bad landing (bouncy) and clipped the tips of his propeller on the runway. Unfortunately, it also split out a piece on one blade from the tip to the root near the trailing edge. Prop scrapped. The RV-3 owner contacted the local EAA group. There was an RV-4 on the field that was for sale and not being flown. They loaned the RV-3 owner the RV-4 propeller to fly home. A Velocity with an MT Propeller was landing at Sun-N-Fun last year, and had to make a go-around right as they were flaring to land. In applying full power with the wheels on the runway, the Velocity over-rotated and the propeller contacted the runway. This removed a small amount of material from each of the blade tips. Although the MT Propeller manual provides specific criteria for damage repair, the owner came to the MT Propeller booth to ask for help. An MT Propeller factory representative looked at the damage, and determined that there were no spanwise cracks in the blades. The repair was to trim the blades to the same length. The permanent repair would be to trim the blades to the same length and paint the exposed wood. Having the propeller rebalanced at the earliest opportunity was also recommended. Regards, Jim Ayers ________________________________ Message 2 _____________________________________ Time: 08:33:12 AM PST US From: LessDragProd@aol.com Subject: RV10-List: Lycoming - tractor engine or turbine smooth? --> RV10-List message posted by: LessDragProd@aol.com Lycoming - tractor engine or turbine smooth? This is the real question that needs to be asked when you are considering which propeller to buy. I had an opportunity to test four different constant speed propellers on one aircraft. There were three different 2 blade propellers and one 3 blade propeller. This aircraft was owned by a friend who flew the aircraft. I just went along as the observer and data recorder. The original CS propeller on the aircraft had been dynamically balanced on the engine. Since the plan was to leave the original propeller on the aircraft when we were finished with the testing, we did not removed the dynamic balance weights from the engine ring gear. All three of the 2 blade propellers had about the same vibration level during their flights. Then we flew the 3 blade propeller. On the takeoff roll and initial climb, I noticed the pilot was highly stressed about something. About mid field, as we were climbing out, he finally said that something must be wrong with the engine. That the engine wasn't producing power. We laughed about this later. We seem to expect a certain vibration level which can be directly related to the engine power. We don't even think about this. And it's not something that any instructor I have had has ever talked about. It's just there. I've been told that a 2 blade propeller has a 2nd order harmonic on the Lycoming engine. And the 3 blade propeller does not have the 2nd order harmonic on the Lycoming engine. What does this really mean? On another test sequence, I had an opportunity to again ride in a friends aircraft. On this friends Harmon Rocket 2 with a stock Lycoming IO-540-C4B5, we removed a 2 blade propeller and installed a 3 blade propeller. The 3 blade propeller made the Lycoming run like it was an electric motor, it was so vibration free. When we install a second 2 blade propeller, the same old vibration came right back. At the same level as the first 2 blade propeller. So the question goes back to you, the builder/flyers. Do you want "turbine smooth" or "tractor engine"? Regards, Jim Ayers ________________________________ Message 3 _____________________________________ Time: 08:37:24 AM PST US From: AI Nut Subject: Re: RV10-List: Damaged Prop? --> RV10-List message posted by: AI Nut It is almost mandatory to get the crank checked whenever one has a prop strike. A friend of mine did this when doing an emergency landing in a field. Prop, spinner, and hub all looked good visually, but he had the crank checked anyway. Good thing, too, as it had cracks necessitating replacement. David LessDragProd@aol.com wrote: >--> RV10-List message posted by: LessDragProd@aol.com > >What do you do if you damage a prop? > >Ask for help. > >I was flying back from Van's Fly-In a couple years ago with another RV-3. >When we landed at the first stop, the other RV-3 made a bad landing (bouncy) >and clipped the tips of his propeller on the runway. Unfortunately, it also >split out a piece on one blade from the tip to the root near the trailing >edge. Prop scrapped. >The RV-3 owner contacted the local EAA group. There was an RV-4 on the >field that was for sale and not being flown. They loaned the RV-3 owner the RV-4 >propeller to fly home. > >A Velocity with an MT Propeller was landing at Sun-N-Fun last year, and had >to make a go-around right as they were flaring to land. In applying full >power with the wheels on the runway, the Velocity over-rotated and the propeller >contacted the runway. This removed a small amount of material from each of >the blade tips. >Although the MT Propeller manual provides specific criteria for damage >repair, the owner came to the MT Propeller booth to ask for help. >An MT Propeller factory representative looked at the damage, and determined >that there were no spanwise cracks in the blades. >The repair was to trim the blades to the same length. The permanent repair >would be to trim the blades to the same length and paint the exposed wood. >Having the propeller rebalanced at the earliest opportunity was also >recommended. > >Regards, >Jim Ayers > > >. > > > ________________________________ Message 4 _____________________________________ Time: 08:41:35 AM PST US From: AI Nut Subject: Re: RV10-List: Lycoming - tractor engine or turbine smooth? --> RV10-List message posted by: AI Nut It may be smoother, but I'm told by prop manufacturers that one will lose a few kts in cruise with a 3-blade. I opted for smoother. David LessDragProd@aol.com wrote: >--> RV10-List message posted by: LessDragProd@aol.com > >Lycoming - tractor engine or turbine smooth? > >This is the real question that needs to be asked when you are considering >which propeller to buy. > >I had an opportunity to test four different constant speed propellers on one >aircraft. There were three different 2 blade propellers and one 3 blade >propeller. This aircraft was owned by a friend who flew the aircraft. I just >went along as the observer and data recorder. > >The original CS propeller on the aircraft had been dynamically balanced on >the engine. Since the plan was to leave the original propeller on the >aircraft when we were finished with the testing, we did not removed the dynamic >balance weights from the engine ring gear. > >All three of the 2 blade propellers had about the same vibration level >during their flights. > >Then we flew the 3 blade propeller. On the takeoff roll and initial climb, >I noticed the pilot was highly stressed about something. About mid field, as >we were climbing out, he finally said that something must be wrong with the >engine. That the engine wasn't producing power. > >We laughed about this later. > >We seem to expect a certain vibration level which can be directly related to >the engine power. We don't even think about this. And it's not something >that any instructor I have had has ever talked about. It's just there. > >I've been told that a 2 blade propeller has a 2nd order harmonic on the >Lycoming engine. > >And the 3 blade propeller does not have the 2nd order harmonic on the >Lycoming engine. > >What does this really mean? > >On another test sequence, I had an opportunity to again ride in a friends >aircraft. On this friends Harmon Rocket 2 with a stock Lycoming IO-540-C4B5, >we removed a 2 blade propeller and installed a 3 blade propeller. >The 3 blade propeller made the Lycoming run like it was an electric motor, >it was so vibration free. >When we install a second 2 blade propeller, the same old vibration came >right back. At the same level as the first 2 blade propeller. > >So the question goes back to you, the builder/flyers. Do you want "turbine >smooth" or "tractor engine"? > >Regards, >Jim Ayers > > >. > > >