A question for Paul...

[Paul Hamilton]

I was able to get into the report and the CG was widened but not by much. This is FD report of differences :

1. The vertical tail area was increased. The rather unpleasant green tail is the 2005, the white
tail is the 2006. This was done both for aesthetic and aerodynamic reasons. This yielded a small
amount of increased directional stability.
2. The trim tab was widened to full span to increase the stick force-feedback for the pilot.
3. The main landing gear legs were strengthened.
4. The loaded CG range for the 2005 CTSW is 13.1" forward, 18.7" aft.
5. The loaded CG range for the 2006 CTSW is 13.2" forward, 18.7" aft.

The repot sounds to me like the typical Cessna/big airplane to LSA transition problem: Not enough transition training and over control. The difference of driving a truck verses a sports car. I am not saying the CTSW is the best design by any means, but it appears the CG range listed in the report expanded the CG range not tighten it up.

[Cub flyer]

Does an 05 fall into that EW CG range?

Does it apply to the April 06 revised 5 sided diagram?

The original diagram was a 4 sided box with vertical sides. Top was gross weight fwd 13.1 aft 18.8

Compare that shape to the current manual.

I'm not sure why that first link does not work. I dragged it over from the page I was looking at. I'll see if I can find another.

[Cub flyer]

The NTSB report does not show that the april 06 revised forward CG range varies depending on weight. It's a lot more than the .1" indicated.

https://wiki.umn.edu/pub/CirrusWing/Cir ... fd_poh.pdf

If I type this into my browser it comes up ok.

This is the 2005 manual. Compare the CG limits on Pg 26 to the current limits

there is no graph.

[Cub flyer]

at 1165 lbs the new forward limit is 14.2" not 13.2 as indicated by FD to the NTSB The limit moves back to 14.9" at gross.

Original 05 manual says 13.1" all the way to gross.


find the WB empty weight and CG for an 05 with tundra gear and see how it works out.

Try it on an O6 also.

Full fuel and solo pilot. no bags.

[roger lee]

through the current LS models and with three different props, at all weights and prop settings. I have flown several other LSA's too so comparisons are fairly easy.
We all (initial CT owners) worried in the early days about doing CG checks for our plane's each flight. We learned early on that you can't get a CT out of CG unless you stick a 100 lb. solo pilot in it or add lead to the tail (figuratively speaking). It will fly up to 1500 lbs. (I know 1320 lbs) and it never has a CG issue provided you put weight where it was designed to be. It flies in all flight configurations like that just fine and can take off at a 10K density altitude heavy, too. It is a very sturdy and forgiving aircraft. Paul's analogy is correct about the types of people learning to fly a CT. First CFI's and high time pilots need transition training and this was lacking earlier on, but is now more adhered to. Second CFI's need to quit teaching in a light aircraft like it is a heavier GA type aircraft. Many of the CT accidents have been from high time pilotsand CFI's flying a CT like they want to, not like it should be (more GA hold over). Our LSA's have a lot less energy and needs to be managed differently. Pilots need to learn to fly using the rudder instead of the heavy station wagon that rarely needs regular rudder input. I have transitioned many pilots and the pilots that have any issue is usually a high time pilot or a CFI. They want to fly a sports car like a station wagon. It is just a light touch aircraft and well balanced. Light touch aircraft is not for everyone and some will never do well in those type aircraft. They will just be better suited for a heavier more docile craft. If you are a heavy hand pilot you will have some training to do to un-learn some of that GA handling. I came out of not only light planes, but helicopters. Transitioning to a CT was just another day in the park.
So the bottom line there is nothing wrong with many of our LSA's, they are just very different from heavier GA craft and a little different from each other. So it is what ever you get used to that is normal. There usually isn't any right or wrong, just different.

[Cub flyer]

Roger, How many inches back is the CG on an 05 with full fuel?
What total weight is it with a 170 lb pilot and full fuel?

How about with your airplane? Empty weight and empty CG?

[Cub flyer]

Paul, Here's an example of what is wrong with the LSA handling and design. It's not in any book I can find but very obvious if you open your eyes.

Walk around the airport and find one Post WWII certified airplane with rounded, airfoil shaped control surfaces. I'm talking about the shape of the ribs in the elevator, ailerons or rudder. I'd be willing to bet you won't find a single one all the way from a 150 to jets.

The reason is as the controls move if they have a rounded surface the center of lift of the control surface will change distance from the hinge line.

Leading to control surface float and variations in control force. Aluminum tube airplanes with large diameter tubes making up the trailing edge do the same thing. Also RV series airplanes where the builder does not form the trailing edge correctly.

Now look at the rudder on a S-LSA or experimental. How many designs have curved airfoil shaped control surface or large diameter trailing edges.

Do they also need large centering springs or have rudder float/variations in pressure?

It's not fuselage length. The Piper vagabond is very short and the rudder has great centering and needs very little rudder attention in flight.

It's not lack of yaw stability but control surface float. Adding more fin area and springs just masks it.

Somebody find me an example of a certified airplane with rounded controls surface ribs. Prove me wrong!!

[dstclair]

I don't mean to paint this unfolding market with too broad a brush, and I'm sure there are good people, reputable businesses and good aircraft folded into this larger mix of entrepreneurs. But boy, does one have to watch where one steps.

Posted from Jack from another topic.

Couldn't agree more that the buyer needs to do their research but this has been true in aviation since the Wright brothers. Jack, remember the blue glue issue with the AA5? I know of wings that delaminated in flight. What about the good old TraumaHawk? Has a list of ADs longer than my Christmas list. All the certified manufacturers have put out what some consider unsafe planes despite all the (useless) FAA oversight. The LSA industry as a whole needs to improve but there are many great LSA planes and great companies out there -- you just need to look.

[Jack Tyler]

"The LSA industry as a whole needs to improve but there are many great LSA planes and great companies out there -- you just need to look."

Quite true. But not complete. One doesn't just 'need to look'; one needs to investigate the builder and the design carefully, as the industry itself is too immature at this point to be relied on for objective information, experienced builders, extensive certification flight testing, etc.

The AA-5 mentioned above was built in 1978 and is making 5 co-owners very happy 32 years later, with the only airframe problems resulting from a bird strike this year. Let's wait & see how we all feel about some of these LSA designs just a decade from now...

[dstclair]

Actually my first sentence specifically said "research" but this applies to purchasing any aircraft. I did fairly extensive research when I bought my two previous certified aircraft. Each model year has changes and the buyer should understand what they are and aren't.

I think you made my point. You have (or had?) what sounds like a nice 1978 Cheetah. Other Grummans may not have been so well built. Grumman changed their lamination process in mid-1976. Being certified didnt magivally change the quality. Were they using their customer base in 75/76 as test pilots?

Both certified and S-LSA industry have their faults and benefits. As always, pick the plane that works best for your mission given your personal decision criteria.

[Cub flyer]

Funny you mention the colored grumman glue. I had to rerivet/rebond a Cheetah tail last year. Really easy to remove and reinstall the surfaces. The bonding was not too bad, getting it scuffed and clean was the hardest part. No debonding a year later so I guess it's ok.


What seems odd is the airplanes I have flown certified under Part 23 seem to have the most strange characteristics/handling. You would think the newer certification rules would help but it did not. The Part 23 manuals are much nicer.

[Ergo1]

Hi Paul

I have a Tecnam p2008 with a 914 Rotax. Currently my prop pitch is set at "4". The other P2008 owners seem to be getting more cruise speed with a
"5" setting. The manager of US Tecnam (not an mechanic) has said my setting at "4" is just right. I will be flying in mostly hot weather at airports at or near sea level. Any suggestions about how to figure out the right prop pitch for my aircraft. I have an annual coming up next week so it would be a great time to make adjustments if necessary.

Can you explain to me in basic terms, how prop pitch will effect my different flight envelopes - takeoff, climb, cruise, ect.

Thank you

Eric

[Type47]

There is a long discussion over on ctflier about prop pitch and rpms.

[3Dreaming]

A decrease in prop pitch will increase RPM and power, so you should have better climb. An increase in pitch should allow the airplane to fly faster because it takes a bigger bite of air with each rotation. Now for LSA airplanes where you can not adjust the pitch in flight you have to fine that overall best pitch setting for you type and altitude you fly at. Now I should mention that I have little experience with the 914.

With a faster LSA airplane you need to set you pitch so that you don't have any issues with overspeed with full power on climb out or when you level off. I suspect you will need to see somewhere around 5000 to 5100 RPM static with the P2008 to get your best all around performance. This is just a guess based on the airplane and propeller combinations I have worked with. I have heard that E props are different in how they are set up, and I will find out soon enough. I'm guessing that you have a Sensenich propeller since you are talking about numbers like that for the pitch. I don't use their pins for prop adjustment. I use a homemade fixture with a digital level, and set the pitch to within 1/10th of a degree of what I choose.

[Ergo1]

Thank you for responding so quickly!
Yes, I have the Sensenich propeller.
You suggest that I adjust my prop pitch to get 5000 to 5100 RPM static with the P2008. Is this something that a neophyte, like myself, can do without extensive training or skill? Does it require special tools? And lastly, if I fly mostly at sea level in hot weather is there a sweet spot for prop pitch? I think that cruise speed would be most important for me.
Thanks
Eric