CTLSi Sport Upgrade

[gbigs]

......

[Doug G.]

That would make the plane no longer fit the light sport category. 120kt max. level flight.

[Roger Lee]

I don't think you're going to find that type of increase. There have been a few kits installed other places and they aren't seeing those numbers. A 100-105 HP is still the same and the rpm is the same so speed remains the same. It will be more efficient on fuel over what it already is and better torque through rpm ranges, but torque with this engine stock was a little disappointing to start with and that's why you have this upgrade to take advantage of its capabilities and not handicap them. 

 

5500-5600 rpm at WOT is still 5500-5600 rpm with or with out the upgrade and that will determine our speed with our ground adjustable prop.

[Ed Cesnalis]

Lone Mountain says they talked to Germany and got those numbers.  I don't care if they exceed LSA standards, I fly as a PP anyway.

 

The 120kt limit is a limitation on the aircraft not the pilot.

[Ed Cesnalis]

An increase from 100 hp to 105 hp?

 

First down to 5,500 RPM = increase from 93hp to 97.65hp or increase of 5%.

 

A 5% increase in power = 0.625% increase in speed

 

120kts x 0.625% = .75kts increase = 121kts

[Doug G.]

CT, isn't it a design limit.

[Doug G.]

I have yet to see a pilot going faster than the plane. :-)

[Doug G.]

I know what you mean, but I couldn't resist.

[Roger Lee]

Remember FD posted speeds for all in the world which means numbers you see are most likely with an in flight adjustable prop. I have already talked with some with the upgrade. You may be disappointed as there are other variables that you won't be able to overcome.

[FastEddieB]

The listed cruising speed for the CTLS is 120KIAS (top of green arc), the LSA standard calls for a maximum speed of 120Kts at max power. Odd?

 

Maybe not if you understand what the top of the green arc represents.

 

 

The FD POH lists the max speed at 127 KIAS at sea level in Section 1.2.

 

I just confirmed that, and unless I'm missing something, that seems to take it out of the LSA class.

 

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

 

What am I missing? FD could have limited maximum continuous power a lá Carbon Cub, but it seems to stand at the 5,500rpm that allegedly results in 127k. They also could hobble it with prop pitch, but that lowered performance should be reflected in the POH.

 

Right?

[Ed Cesnalis]

Perhaps reality isn't the basis for conforming with this limitation?

[FastEddieB]

 

In practice, right now before the sport upgrade, I have 'inadvertently' flown faster than 120KTAS in the CTLSi.

 

Are you implying you think you may have done something wrong?

 

Nothing says you cannot fly a CTLSi faster than 120k - only that it must be designed not to exceed that speed at maximum continuous power on a standard day at sea level.

 

In a descent, anything goes. Same with riding thermals. If you can consistently cruise at 120k+ at 5,500 rpm, that could be an issue with the plane's design meeting ASTM standards.

[Doug G.]

Overloading the plane is a different matter, and the FAA can bust you for that.

[FastEddieB]

FastEddie...

 

The top of the green arc is 120KIAS.  That is a reference to what FD says is the cruise speed for the CT. 

 

The FAA says the MAX speed for LSA is 120kts.

 

The max speed for 'all operations' from the POH says 145KIAS.  The max speed from the Performance Specifications as stated in the POH is:

 

1) Definitions are important. The top of the green is Vno. Its more a structural limitation than a predictor of performance.

 

...the top of the green arc is the Velocity (V) of Normal (n) Operations (o) or Vno. This is the maximum structural cruising speed. Operation of the Aircraft at the Vno speed, and lower, is within the certified range for operations within gusts. The aircraft is certified to withstand substantial wind gusts without experiencing structural damage. Operations above Vno move into the Yellow Arc on the Airspeed Indicator. Do not exceed Vno, except in Smooth Air, and only with caution.

 

"The FAA says the MAX speed for LSA is 120kts."

 

No, it doesn't. At least not in those terms, as others are trying to point out.

 

That excerpt from the POH, 1.2, shows how important definitions are. I assume 145k is Vne. I'm not sure what the POH is getting at with "Maximum Speed" of 127k. Because "maximum speed" is not well defined. I'd guess that the maximum cruise speed under specified conditions, but I don't think that term is commonly used - since it could mean many different things.

[Doug G.]

True, of course, but when I hear that a plane is being modded to hit 135 kts in level flight it catches my attention. And, the forum is here for conversation about these sorts of things.

[Doug G.]

Doesn't Carbon Cub keep their 180 hp machine LSA by POH and placard limitation? Or is that just rumor?

[WmInce]

Doesn't Carbon Cub keep their 180 hp machine LSA by POH and placard limitation? Or is that just rumor?

Actually, during the Sebring Light Sport Expo, I was told by Chip Allen, from Cub Crafters, that the ground adjustable prop is pitched to keep the airspeed below 120 knots.

[dhelmich]

Hi,

 

i own a CTLSi from Jan/2014, a german based LSA. It is equipped with a constant speed prop, and the flaps go to -12.

At full power and 5700 rpm at sea level it speeds up to an IAS of 120kn maximum.

So, the effect of constant speed and -12 degrees flaps is not so heavy.

 

I am waiting for the 912is sports upgrade - but Flight Design expects first deliveries in 11/2014 for LSA.

They also propose, that the next dynon skyview upgrade will be version 11 - perhaps in 10/2014.

 

greetings form germany,

Dietmar

[FastEddieB]

True, of course, but when I hear that a plane is being modded to hit 135 kts in level flight it catches my attention. And, the forum is here for conversation about these sorts of things.

Yes.

 

And though I'm not with the FAA, if I were and reading through this thread, I'd look at two facts stated and go hmmmm :

 

1) CTLS POH giving a maximum continuous power cruise speed of 127k, and,

 

2) The ASTM LSA maximum continuous power cruise speed limit of 120k.

 

I might then undertake to resolve the conflict, either by:

 

1) Having FD revise their POH to correct the error, or,

 

2) Have FD "slow down" the CTLS to lose the extra 7k (limit maximum continuous power, change prop pitch, add drag, whatever) or,

 

3) Revoke the CTLS certification as an LSA.

 

In general, faster planes are a good thing. I wish mine was. But mods or base performance that exceeds the ASTM standards could make for a real problem for a manufacturer or an owner.

[Ed Cesnalis]

Yes.

 

And though I'm not with the FAA, if I were and reading through this thread, I'd look at two facts stated and go hmmmm :

 

1) CTLS POH giving a maximum continuous power cruise speed of 127k, and,

 

2) The ASTM LSA maximum continuous power cruise speed limit of 120k.

 

I might then undertake to resolve the conflict, either by:

 

1) Having FD revise their POH to correct the error, or,

 

2) Have FD "slow down" the CTLS to lose the extra 7k (limit maximum continuous power, change prop pitch, add drag, whatever) or,

 

3) Revoke the CTLS certification as an LSA.

 

In general, faster planes are a good thing. I wish mine was. But mods or base performance that exceeds the ASTM standards could make for a real problem for a manufacturer or an owner.

 

Do you see 127kts cruise in the POH?  Do you have a link?  That sounds wrong.

 

I think the CTSW is faster and 127 is a too fast number for a CTSW I don't the the CTLS is even close to that fast.

[FastEddieB]

Do you see 127kts cruise in the POH?  Do you have a link?  That sounds wrong.

 

I think the CTSW is faster and 127 is a too fast number for a CTSW I don't the the CTLS is even close to that fast.

 

100Hamburger posted a screenshot in Post #18.

 

Admittedly, I'm not seeing that in the downloadable CTLS POH's I can find, at least not under 1.2.

 

Maybe that's for the non-LSA version?

[FlyingMonkey]

There is a difference between "top speed" and "top speed at maximum continuous power".  The latter is what is restricted to 120kt CAS at sea level.  I'm guessing the 127kt is at 5800rpm, which is above the maximum continuous rpm of 5500rpm, and would therefore be perfectly legal.  I have hit numbers similar to that when pushing my engine up past 5500rpm for short periods.

 

These numbers are all also reported on a standard day at 15°C and barometric pressure of 29.92 inHg.  There is never s standard day around when you need one. 

[FlyingMonkey]

True, of course, but when I hear that a plane is being modded to hit 135 kts in level flight it catches my attention. And, the forum is here for conversation about these sorts of things.

 

If that number came from FD Germany, it it probably in German configuration with -12° flaps and in-flight adjustable propeller.  No CT is hitting 135 knots on 105hp in the US configuration.

[FlyingMonkey]

And I didn't suggest otherwise.  I'm wondering if it would be possible to modify your plane and lose your LSA certification?

 

If it was that heavily modified, it could not be certified at all.  It would no longer meet LSA definitions, so it could not be either S-LSA or E-LSA.  It's not certified, so it could not be standard category.  It's not amateur built, so it could not be E-AB.  It *might* be able to be certified as Experimental Exhibition, but I'm not sure of all the rules on that and there a re *significant* limitations on how you fly under that classification.

[FlyingMonkey]

Okay, I looked at 100Burger's screenshot...here's the loophole:

 

The POH says 127kt IAS.

 

Maximum LSA speed is 120kt CAS in level flight at maximum continuous power at sea level.

 

IAS is not CAS.