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John

CTLS at the Deland Showcase November 3-5

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I'll  post a few guesses:

 

-  CT4 update 

-  914 Turbo option

 

They can't put a 914 Turbo in a CT or any other SLSA.  It would fly too fast and the weight would be prohibitive.  A C4 update would be more likely, but unless they come out with the C4 in the next two years they will be too late to market. 

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They can't put a 914 Turbo in a CT or any other SLSA.  It would fly too fast and the weight would be prohibitive.  A C4 update would be more likely, but unless they come out with the C4 in the next two years they will be too late to market.

 

There are some SLSA out there already with the 914, and Flight Design at least had a brochure for a CT with a 914 as an option.

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I note that the Carbon Cub SS LSA has an advertised weight of 896 lbs. with 180 hp for up to 5 minutes for takeoffs and then the pilot is directed to go to a power setting which delivers 80 hp for cruise speed "not to exceed" 120 kts.  Yeah, right.  Everyone who owns one is surely going to throttle back to make sure they cruise at 120 kts.  A CTLS with the 914 would have less power with about the same weight as the Carbon Cub.  I wouldn't think it should be a problem - as long as the pilot, uh,  watches the speed. :rolleyes:

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I could have sworn the limitation was that an LSA --- the aircraft itself --- could NOT have a V-h in excess of 120 kts.     If I'm not mistaken, that means at WOT, given Standard Temp and Pressure, the aircraft does not fly faster than 120kts.   What am I missing here?

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Yes, WOT only allowed at takeoff.  POH cautions the owner/operator to only keep the throttle at WOT for max of 5 minutes during takeoff and DO NOT use WOT after reaching max cruise speed of 120kias!  Sure does leave a lot of unused throttle which is very tempting to use.  Anyone cruising at 120 or so kias get passed up by a Carbon Cub lately??  :o

 

Pointpergame, my understanding is that CC instructs the operator of their aircraft that it is their responsibility to adjust engine power to insure the aircraft does not exceed 120kias in cruise. This appears to be allowed under LSA rules.  I believe that CC also states that there are no mechanical mechanisms, such as a  governor, on the aircraft which will automatically limit the power and it is up to the operator to do this so that the max. speed is not exceeded.

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The definition for Light Sport is in 14 CFR 1.1, and part H defines the cruise speed limitation: "(2) 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."

 

My CTSW's POH has max continuous at 5500 RPM. 

 

The operating manual for the Titan 340CC engine used in the Carbon Cub shows maximum continuous horsepower at 80 and the cruise tables that show rpm and fuel consumption are all geared to that number. (2000 - 2300 RPM @ ISA)  You only get the 180 HP at 2700 RPM immediately after takeoff; the operating instructions ask you to come back to 2500 RPM in the climb as soon as you can.  Those 180 horses are going to cost you 16.2 gals/hr.

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Thanks Andy.  What do you think would be the max. cruise speed for the CC at the higher rpm's?  I'm thinking it's pretty draggy but there is still a lot of power available to use?

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They can't put a 914 Turbo in a CT or any other SLSA.  It would fly too fast and the weight would be prohibitive.  A C4 update would be more likely, but unless they come out with the C4 in the next two years they will be too late to market. 

 

There are several SLSA flying in the US with 914 turbos in them.  Here is an article from 2014 about the Tecnam P2008 turbo.  

 

https://www.aopa.org/news-and-media/all-news/2014/april/pilot/1404p_tecnam

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Thanks Andy.  What do you think would be the max. cruise speed for the CC at the higher rpm's?  I'm thinking it's pretty draggy but there is still a lot of power available to use?

 

 

Dick,

 

You need some altitude to comfortably use the turbo power.  Down low you want to throttle back because of the thick atmosphere causes too much noise.  At 12,000 you can comfortably cruise at 150kts TAS and not even break 120kts IAS.

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Dick,

 

I don't have a clue; I got that info by pulling up the info from the web.  (http://titanengine.com/pdf/Titan_340CC_Operations_Manual.pdf)  I think there is a Carbon Cub out at KLVJ but I've never talked to the pilot about it.  I suspect you're right; but my impression looking at that stuff is that you aren't going to be able to stay there long enough for it to be much of factor for cruise.  The operating limitations quote a 475 degree max CHT for climb and 450 max for cruise.  The admonition to throttle back during the climb makes me think the engine runs on the hot side.

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Andy, yes, heat might be a problem.  CT, interesting about IAS and TAS at altitude and noise from the 914 at low altitude. Is LSA 120kt. limit TAS or IAS?  I'm thinking it's IAS?  Does the heavier air at low alt. cause the turbo to work harder, this make more noise?

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There are several SLSA flying in the US with 914 turbos in them.  Here is an article from 2014 about the Tecnam P2008 turbo.  

 

https://www.aopa.org/news-and-media/all-news/2014/april/pilot/1404p_tecnam

 

Notice the performance spec for this plane:  Max level speed, sea level | 120 kt    and an anemic 1100fpm climb at sea level.  Wonder how they restricted performance?  It's also $220k.  A tad above what most guys want to pay for an SLSA...sorta sounds like the ill-fated ICON.

 

A higher horsepower turbo is wasted unless you plan to fly far above the 10,000 foot height restriction and cruise at 150ktas or more.  Wasted fuel, added complexity, wasted money and in violation of the rules.

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The extra power of a turbo could help a lot with climb and acceleration.  Simply put a prop pitch or continuous RPM limit in the POH for that engine and done.

 

915is powered CT with 2000fpm climb anybody?     B)  

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I note that the Carbon Cub SS LSA has an advertised weight of 896 lbs. with 180 hp for up to 5 minutes for takeoffs and then the pilot is directed to go to a power setting which delivers 80 hp for cruise speed "not to exceed" 120 kts.  Yeah, right.  Everyone who owns one is surely going to throttle back to make sure they cruise at 120 kts.  A CTLS with the 914 would have less power with about the same weight as the Carbon Cub.  I wouldn't think it should be a problem - as long as the pilot, uh,  watches the speed. :rolleyes:

 

The power reduction for the Carbon Cub SS has nothing to do with speed. If you look at the cruise speed with 80hp it is only 89 mph. VNE is 141MPH or 122KTS. The reason for the power restriction is to meet the ASTM minimum useful load requirement. There is a formula that figures pilot weight per passenger seat and minimum fuel required based on HP. They had to reduce the maximum continuous power to the point so that the required fuel weight plus the pilot and passenger and aircraft empty weight did not excede 1320 pounds.

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Andy, yes, heat might be a problem.  CT, interesting about IAS and TAS at altitude and noise from the 914 at low altitude. Is LSA 120kt. limit TAS or IAS?  I'm thinking it's IAS?  Does the heavier air at low alt. cause the turbo to work harder, this make more noise?

 

The limit is calibrated airspeed.

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I could have sworn the limitation was that an LSA --- the aircraft itself --- could NOT have a V-h in excess of 120 kts.     If I'm not mistaken, that means at WOT, given Standard Temp and Pressure, the aircraft does not fly faster than 120kts.   What am I missing here?

 

Vh means velocity at maximum continuous power, not WOT. There are several engines that have a time limit for how long you can use maximum continuous power.

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Tom, the "minimum useful load requirement" reason for limiting the CC's hp involves a lot more than I realized.  Thanks for the details.  Also thanks for explaining Vh or "maximum continuous power and it's relationship to airspeed for LSA aircraft.  More lessons learned.

 

I didn't realize that "John" who started this thread is John Hurst.  I guess there will be an important surprise for the attendees at the upcoming DeLand event!  There are two threads going on this event.  Congratulations to John regarding his new endeavor!

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  Thanks for the details.  Also thanks for explaining Vh or "maximum continuous power and it's relationship to airspeed for LSA aircraft.  More lessons learned.

 

 

Ditto.   

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... talk about thread creep...  but I wonder if the big news is the new AeroJones facility in Florida?

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... talk about thread creep...  but I wonder if the big news is the new AeroJones facility in Florida?

I do too, I think DeLand would be a great location, but there are many good locations in Florida. Tecnam is in Sebring. Good location for Flight instruction and Demos.

 

Cheers

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