130kts TAS :)

[Ed Cesnalis]

It was 28*F this morning at Mammoth Yosemite Airport.  At 13,000' this translated into 130kts sustained TAS.  

 

You will often hear here how my prop sucks and my pitch is wrong and I don't know how to set my throttle and its all true.  I wonder how I manage 130kts?  Just lucky I guess.

 

Here is a photo of Mt Lyell, the highest point in Yosemite as I cruise by at 130kts

 

[Scrapman1959]

Well I will be the first to tell you that TAS is not accurate, unless of course you have a 914 turbo charged engine? How many HP you think a regular 912 ULS is producing at 13,000 and probably DA of over 14,000, if it was that warm.....maybe 65 or 70? The only other way you were getting 130 TAS knots is nose down in an updraft while AP try's to hold you level at its assigned altitude.

[Ed Cesnalis]

Over 10 years my TAS has been pretty believable.  I was only using the horizontal AP so if it was a downdraft it was a sustained one.

 

I'm not claiming accuracy just that I hit peak speed and my CT has always been a fast one.  It was 28*F at 7,000' so I doubt it was anything like 70* at 13,000'.  It was the first morning below freezing this year.

 

HP is low at 13k but I'm pitched for winter and it was a cold summer day.

[Scrapman1959]

I meant HP at that altitude would be down around 60 or 70 HP. Now I realize the air is thinner at 13,000 ft but you can't make much HP there either. Most normally aspirated AC sweet spot is between 7000 and 9000 ft. What was your IAS reading? And BTW, most all of these dynons are off by 5% or more. All of them reading faster than actual. I have owned 4 of them and they read faster than GPS calculated fly a box ground speed. My guess is yours is off more than most. And while you are flying a box to get real TAS, the IAS must be rock solid throughout the box or nothing will be accurate. In other words no thermal or mechanical up or down movement of the air you are flying thru while flying the box to check TAS. I'm not saying your CT can't do 130 knots, I just bet it can't do it at 13,000 ft.

[Tom Baker]

I meant HP at that altitude would be down around 60 or 70 HP. Now I realize the air is thinner at 13,000 ft but you can't make much HP there either. Most normally aspirated AC sweet spot is between 7000 and 9000 ft. What was your IAS reading? And BTW, most all of these dynons are off by 5% or more. All of them reading faster than actual. I have owned 4 of them and they read faster than GPS calculated fly a box ground speed. My guess is yours is off more than most. And while you are flying a box to get real TAS, the IAS must be rock solid throughout the box or nothing will be accurate. In other words no thermal or mechanical up or down movement of the air you are flying thru while flying the box to check TAS. I'm not saying your CT can't do 130 knots, I just bet it can't do it at 13,000 ft.

 

A couple things for you to consider. He is flying a early CT which is lighter. He is using a different propeller than most other CT's. He has a different display than a Dynon, so the typical Dynon type error may not apply. IIRC from the forums, at the early CT fly ins when the did group flights his airplane was always faster than the others in the group.

[gbigs]

A couple things for you to consider. He is flying a early CT which is lighter. He is using a different propeller than most other CT's. He has a different display than a Dynon, so the typical Dynon type error may not apply. IIRC from the forums, at the early CT fly ins when the did group flights his airplane was always faster than the others in the group.

 

Lighter?  The biggest variable in any of these planes is the pilot and fuel weight.  The SW is NOT a faster plane than any of the other CT models.

[FlyingMonkey]

Horsepower is reduced at altitude, but so is drag. I can get 130kt TAS in my airplane pretty easily at any altitude I fly at, and have seen 135t TAS. Above 7000ft or so you are beyond the most efficient cruise altitude for naturally aspirated engines, but I can believe CTs speed if his airplane is setup well and conditions are right.

[FlyingMonkey]

Lighter?  The biggest variable in any of these planes is the pilot and fuel weight.  The SW is NOT a faster plane than any of the other CT models.

LOL...so pilot and fuel weight are important, but airplane weight means nothing?

 

Man, I hate how capricious and inconsistent physics is.

[Ed Cesnalis]

My CT is 719lbs,  I weight 170,  had ~ 100llbs of fuel.  I was under 1,050 lbs.    Temps were below freezing on the ground.

[Tom Baker]

Lighter?  The biggest variable in any of these planes is the pilot and fuel weight.  The SW is NOT a faster plane than any of the other CT models.

 

Weight absolutely does make a difference. I'll bet his airplane is over 100 pounds lighter than your old CTLSi. That is over a 10% lighter, and a significant factor.

I have flown many of the CT models. The SW. both versions of the LS, MC, and CTLSi. The CTSW's seemed to have a bigger difference in speed between airplanes, but some of them were certainly faster than any of the other models.

[gbigs]

LOL...so pilot and fuel weight are important, but airplane weight means nothing?

 

Man, I hate how capricious and inconsistent physics is.

 

Physics is never the issue in these threads...it's always the goofy assertion that an SW is somehow faster or is in any way a better plane than the fuel injected models simply because there is a 30lb weight difference in the superior 912iS engine versus the antiquated 912ULS engines (a weight delta easily erased by a fat pilot versus a trim, healthy one).  

 

The same circle-pull happens when comparing the more sophisticated Dynon/Garmin panels versus the old steam gauges and iPad based PFD/portable ADS-B solution.

[Ed Cesnalis]

My 719lb empty weight is more than 30lbs lighter.  

 

Other pilots / passengers may weigh more than me and Erin.  We total less than 300lbs.  I don't get how the fact that others weigh more some how negates this weight advantage.

 

When I used to see pilots getting ready for the Reno Air Races they never added weight.

 

========================

 

PS  The lightest CTs are the fastest CTs.  Newer ones have more weight and drag, that does make them slower.  The are longer too so a bit less nimble.

[Tom Baker]

Physics is never the issue in these threads...it's always the goofy assertion that an SW is somehow faster or is in any way a better plane than the fuel injected models simply because there is a 30lb weight difference in the superior 912iS engine versus the antiquated 912ULS engines (a weight delta easily erased by a fat pilot versus a trim, healthy one).  

 

The same circle-pull happens when comparing the more sophisticated Dynon/Garmin panels versus the old steam gauges and iPad based PFD/portable ADS-B solution.

 

The debate is not about whether the 912iS is better than the 912ULS. It has nothing to do with avionics. It is a simple discussion about weight. The average CTSW is going to be 50-60 pounds lighter than a base CTLS. The weight of the base CTLS goes up another 20 for the 10" dynons. By the time you get to the CTLSi there is a 100 pound difference between the CTSW and the latest and greatest.

 

Now for the physics. If you have the same pilot and same amount of fuel the CTSW will be 10% lighter than the CTLSi. Because it is lighter the wings have to carry less weight. The less weight translates into lower angle of attack. the lower angle of attack means less drag. Considering that both airplane have engines with the same horse power, the airplane with the lower drag will always be faster.

 

On the other end if you are both at gross weight the speed difference will be less, but there are still trade offs. Ct can take him and Erin at 300 pounds, put in full fuel and carry 97 pounds of baggage. How does that work out in your old plane? I don't remember what you posted for an empty weight, but I seem to remember it was around 830. If you put on the same pilot load, add 204 pounds of fuel to match what he is carrying, and then add baggage. Oh wait, you cant add baggage, because the 204 pounds of fuel put you over gross weight. Even if you reduce the fuel carried because of the super reduced fuel flow of the 912iS to match the endurance of the CTSW, you still can't carry as much weight.

[FlyingMonkey]

Well said Tom.

[Scrapman1959]

Instead of trying to calculate how fast an AC is by these inaccurate avionics, fly a box pattern in perfectly stable air WOT and divide the 4 total GS after each heading has settled out to its max speed and divide the total by 4. That's how fast your AC is. As earlier stated, this needs to be done in early morning very stable air, or it will not be accurate. Any fluctuation in IAS throughout the box pattern will skew the accuracy of the test. Our Evolution with Garmin G1000 (G900 is the official name when installed in the Evo) reads 13 knots slow TAS in the upper 20s when flying at normal cruise of 290 knots depending ISA temps. I do agree a heavier plane with same HP etc will be slower, as we see an extra 7 to 10 knots in our Evo last hour of 3.5 hour legs when 100 gallons of fuel is missing from the gross weight.

[IrishAl]

 

  I wonder how I manage 130kts?  Just lucky I guess.

 

 

 

Ahem......doesn't that make you, kind of, er, illegal?

[FlyingMonkey]

I wonder how I manage 130kts?  Just lucky I guess. 

 

 

Ahem......doesn't that make you, kind of, er, illegal?

No. The LSA speed limit in the US is for calibrated airspeed at sea level in a standard atmosphere, which never happens. Plus the limit is something the manufacturer has to comply with, not the pilot. As long as we don't modify our planes to make them faster, we are legal to get whatever speed we can.

[gbigs]

100Hamburger: "I don't comment on aircraft I don't own or fly."

 

I did own and log 200 hours in a CTLSi.  So I do comment on aircraft I have flown.  You guys are so busy playing gotcha you forgot or were unable to decipher the text.

[gbigs]

No. The LSA speed limit in the US is for calibrated airspeed at sea level in a standard atmosphere, which never happens. Plus the limit is something the manufacturer has to comply with, not the pilot. As long as we don't modify our planes to make them faster, we are legal to get whatever speed we can.

 

The regs: "A maximum airspeed in level flight with maximum continuous power (V _H) of not more than 120 knots CAS under standard atmospheric conditions at sea level."

 

The difference between the indicated and calibrated airspeed is minimal at cruising speeds (insignificant).  Thus, KIAS is close enough to determine if the plane is flying within allowed limits at other than sea level altitudes.

 

The statement "manufacturer has to comply not the pilot" has no meaning.  The aircraft MUST NOT exceed 120 KIAS in level flight to be a compliant LSA aircraft. 

 

And Morden being a Sport Pilot in particular must not fly:

• At an altitude of more than 10,000 feet MSL or 2,000 feet AFL.
• When the flight or surface visibility is less than 3 statute miles.
• Without visual reference to the surface.
• If the aircraft has a maximum forward speed in level flight that exceeds 87 knots CAS, unless having met the requirements of §61.327.  And only up to a maxium of LSA limits.

[Tom Baker]

Trying to rewrite the regulations now?

 

The 120kt Vh restriction is for the airplane, not the pilot.

[FlyingMonkey]

The statement "manufacturer has to comply not the pilot" has no meaning.  The aircraft MUST NOT exceed 120 KIAS in level flight to be a compliant LSA aircraft.

 

 

Exactly, this is a compliance requirement for the aircraft (e.g. the manufacturer) to meet, not the pilot.  Thanks for agreeing and making my point.

[Scrapman1959]

I'm anxiously awaiting 4 screen shots of GPS GS at or above 13,000 ft in stable air going in four magnetic headings each 90 degrees of the the prior heading. I'm offering a tank of gas to CT if his plane can sustain 130 knots at that altitude and at least 1/2 full fuel. I don't want him up there on fumes trying to prove a point and run out of gas..... Kidding of course CT you are smarter than that.

[Anticept]

So here's my personal thoughts about pilot responsibility.

 

Light sport is defined in 14 CFR 1.1. It has the 120 knots limit there (there's more to it, but let's just keep it simple). It also states "has continued to meet, since original certification"...

 

With that said, it doesn't say anything about airworthiness certificates. It's defining what a light sport is.

 

Light sport airworthiness certificates are defined elsewhere, and also point back to 14 CFR 1.1. But that's not the big catch. I believe the oerating limitations of the airworthiness certificate says something about it must meet the definition, but I won't be able to look for a couple hours.

 

Part 61.315 states one may operate a light sport aircraft except provided in ©.

 

( C )(15) Contrary to any operating limitation placed on the airworthiness certificate of the aircraft being flown.

 

Of the airworthiness operating limitations do say definition of light sport or 120kts or the like, then it is the pilots responsibilty.

 

I wouldn't go waiving flags around over this though. There's a lot of factors beyond what I said. Good way to get an overreaction as this thread has shown!

 

Edit: this is to make a point about pilot responsibility, not to go bashing on anyone specifically or saying anyone is doing illegal things.

[Tom Baker]

Corey,

 

The CFR 1.1 requirement is for a maximum level flight speed of 120kts CAS, at maximum continuous power, at sea level under standard conditions. This measurement would have to be done with special test equipment, under precisely monitored test conditions. Unless the airplane has been modified it should continue to meet the requirement.

 

The 120KTS is simply a measurable base line for certification, anytime you have anything different that the standard conditions called for in the definition all bets are off as to what the speed might be. The fact that a pilot might see an indicated or true airspeed higher than 120kts is no cause for alarm. It is not beyond what is required for the CFR 1.1 definition to be a LSA, and it is not outside of the operating limitations for the airplane.

[Anticept]

I agree Tom. I specifically excluded anything about the type of speed or the conditions it falls under, I was just addressing the fact that a pilot can't just shrug their arms if they were finding themselves going 200 knots under reasonable conditions and say "but it's an LSA!".

 

Which is why I also say, no need to go nuts over a few knots!

 

I'll make a small edit to clarify.