Thread: CTLS and high altitude airports

Originally Posted by Redpenny

... it shows the plane able to take off in just about a worse case at 9300 DA ...

here in mammoth lakes da gets about 2,000' higher then 9,300 and i never need that much runway and time to climb. tim's prop must be pitched really flat

Originally Posted by Redpenny

...and how the plane acts in what must have been some strong thermals judging from the motion of the wings and the camera...

david, maybe what you are seeing is the result of light wing loading in less then strong thermals? the ctsw has a more solid ride then i would expect but it is a different beast then your six.

While it was Arizona in the Summer, the thermals weren't THAT strong... the camera location amplifies the motion quite a bit. But it does bring up the point - LIGHT is a real part of LSA. It can get a bit bumpy.

Re-pitching the prop is pretty easy, provided you have the right tools and a bit skill. I think Roger Lee claims the "world re-pitch a prop" record.... what is it Roger, 25 minutes??? I'm pretty sure it's considered a user adjustable maintenance item.....(Give me some help guys).

Altitude over Sedona was around 9,000.

Tim

Originally Posted by Redpenny

You say the prop was pitched for lower altitudes. What is the procedure for re-pitching the prop. Is it something that you can do yourself or is it an A&P thing?

David,

I haven't checked my manual, but likely an LSR-M or A&P are required. It's not that complicated a procedure, but not something I'm comfortable doing on my own, even if allowed. Roger Lee or one of the other mechanics on the forum can better explain the procedure than I can.

Basically, you want to have your prop pitched to achieve 5,500+ RPM with wide open throttle, at a selected altitude, that you typically cruise at. I have mine pitched to see that at 7,500'. With that setting, I can still see 5,300+ rpm up at 13,000' DA. Someone in the flatlands, will likely have their's set for a lower altitude, while CharlieTango is set for higher. The engine develops it's highest HP at high rpm, and higher elevation and higher temps will reduce performance. This is especially true with climb performance.

Time of year that the adjustment is done is something to consider as well. If it's adjusted in the cooler time of the year, you will see reduced performance come the summer. Having it done in the summer provides the benefit of seeing increased performance when it's cooler.

Charlie, Yeah the 6 is like flying a cruise ship. Big and stable, turbo, constant speed prop, I am not expecting that with the CT. I am very willing to make the trade-offs to get the economy and flexibility of the CT, it will allow me to fly more which is my goal. I am glad to hear that the CT is stable for its size and configuration, that is important to me.

Tim and Roger F., Thanks for the info on the re-pitch. I watched the video again and could see that the wing was probably doing most of the dancing, expected. I have flown that area some in both the Archer and the 6 and even the 6 got tossed around some. OK so it's an A&P thing to change the prop. It may sound silly but are the guys that work on GA planes going to be able to do this on an LSA without special training? The mechs at KPAO are pretty good guys but I am not sure they have worked on LSA's. I found out that Kurt is at KPAO so I can ask him and Roger, you have your CT at KRHV, who do you have work on it?

This is all very encouraging and helpful and I feel lucky to have stumbled upon such a knowledgeable crowd, thanks for the help.

David,

An airplane you buy, might not even need a prop adjustment at all. Early on, Flight Design (FD) was delivering planes with the props pitched incorrectly, thinking they were limiting the speed to LSA regs, which they were wrong about. They were actually causing additional load on the engine, allowing faster than LSA reg speeds, and reducing safety. When I received mine, I was seeing less than 5,300 rpm wide open throttle at 3,000 feet. It went severely downhill at higher altitudes, and up at 10,500 - 11,500 it was pathetic. I'd see 4,700 rpm wide open throttle there. Had I gone into KBCE and departed at 9,500' DA, it could have been ugly. The plane was fast though, as I was seeing 130 - 133 KTAS in cruise at 3,000 - 5,500, but the climb performance was nothing to write home about. Thus, I needed to have the prop repitched.

FD has learned alot in the last 3 years, and may have the prop pitched correctly on a new airplane these days.

I have used several A&P's & Light Sport Repairmen to work on and do inspections on my plane. Roger Lee out of Tucson has done one of my annuals, and got my prop set where I like it. I am presently using an LSR-M that is based out of Redding and Corning, who does great work for cheap prices. He also makes house calls. In a pinch, I can use Victory Aero at RHV. The mechanic situation is improving, and will continue to do so. Piper using a Rotax in the PiperSport is certainly going to help that. You need a mechanic that is Rotax certified.

Roger,

I like the house calls part... If it is just a matter of dialing in the prop for 80% of the missions that is fine. And maybe then doing a re-pitch for the summer months when we get the high DA's if necessary. I would be looking for Archer like speeds, say 120-122ktas cruise and it sounds like at those speeds the prop would be in good shape to handle the altitude. Again I am educated. That is why I am asking so many questions, I like being very well informed and I hope that I am not being a pest! Thanks.

David,

At my prop setting, I cruise at 120 KTAS with 5,200 - 5,300 rpm. I can get a bit more out of it, if I run it higher. No problem with all the questions.