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Fastest Light Sport Airplane?

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rrruuunnn

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Within the Light Sport Airplane category, which airplane is the fastest for long cross country flights?
 

addaon

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Many designs, especially the pre-built ones, max out the category. Differentiation would be range (fewer stops for really long flights) and, I suppose, a turbo (IAS is restricted, not TAS); but I don't know of any pre-built shipping with a turbo.
 

pwood66889

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Kind of an oxymoron, Run; LSA is restricted as to top speed. Now, if you're asking about range, here's a data point:
The Ercoupe has 22 gallons on board (9 each in two wing tanks; 6 in the header) and uses 5 gallons an hour in cruise. That makes for 4 hours range. At approximately 100 MPH cruise speed, that yields 4oo Statute Miles. The same logic is used with any LSA, but watch out for overly optomistic marketing!
Percy in NM, USA
 

MalcolmW

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Jan 21, 2007
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Hello, Rrruuunnn (I hope I got that right);

there are a lot of 'detuned' LSA aircraft in the USA which have props that limit their performance to meet the legal requirements. However, I did notice that there is one aircraft that claims to meet the requirements for LSA, while giving details about its performance as a non-LSA aircraft. Take a look at the Pipistrel Virus SW aircraft. See details at: Sinus Virus and Taurus Motorgliders by Pipistrel

It also has flown some impressively long flights over the Tasman Sea (from Australia to New Zealand).

Fly safe. MalcolmW
 

N15KS

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The top speed of LSA are all restricted to <120 knots. If you want to go faster without needing a medical, you can get a glider license (no medical required) and fly a motorglider. The Pipistrel Virus motor-glider has a 121.5 kt cruise, 129.5 kt top speed and 800 sm range.

Another consideration is that sport pilots cannot fly at night or above 10,000ft. Additional training is required to operate in class A, B, C or D airspace. Glider pilots have fewer restrictions with privileges closer to a private pilot.

 

mcjon77

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One thing is to remember is that top speed is limited to 120kts IAS NOT TAS. This is usually related to max continuous RPM of the engine. In other words, an LSA can have an IAS no higher than 120kts when running at it's max contious RPM. Therefore, the fastest LSA should be the one with an engine that can maintain max contious RPM (and thus 120kts IAS) at the highest altitude.

For example, a Rotax 912ULS has a Max RPM of 5800 and a max continous rpm of 5500. at 5500rpm the engine is running about 90% power. The highest altitude it can attain and still run at 5500rpm/90% power is roughly 3000ft. At that altitude, if IAS is 120kts, TAS should be roughly 127kts. If it flies higher than 3000ft it will not be able to maintain 90% power/5500 rpm and thus TAS will decrease.

Now a Jabiru 3300L has a max rpm of 3300rpm but a max continous rpm of 2850rpm which is estimated at less than 75% of total power. As a result a Jabiru 3300L engine can maintain max continuous rpm of 2850 at and above 8000ft. At an altitude of 8000 feet, if IAS is 120kt, TAS is almost 140kts.

To take it a step further, the turbocharged rotax 914 can maintain its max continous rpm to as high as 15,000 ft (although as of now, Sport pilots can not fly above 10,000 ft). At 10K ft with an IAS of 120kts, the LSA should be cruising at around 144kts TAS.

All this assumes that the airframe is clean enough to reach the 120kt IAS limit at it's max RPM. For example, a STOL 701 isn't coming close to that speed with any of the above mentioned engines. It is just too slow.

Hope this helps. My numbers are rough estimates.
 

rrruuunnn

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These comments are far more better than I'd imagined. Thanks for all the serious replies.
 

mcjon77

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I almost certain my local CFI is not rated for glider instruction.

Is the Zodiac CH650 one of the fastest LSA's (160mph @ 8,000 ft)?

ZODIAC XL Performance - CH601 Kit Plane
Nope. Every owner/builder I have talked to say that the Zodiac cruise numbers are HIGHLY inflated. with a 100hp Corvair or continental most guys are seeing cruise speeds of ~125mph TAS at 8,000ft.

I have heard that the demo plane with a Jabiru 3300 can get up to the high 130's at 8,000, but have never heard of anyone getting 160TAS with anything other than a dive. Most of the other Jabiru guys flying Zodiacs are getting mid to low 130's.
 

gschuld

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Perhaps what you are really asking for is what LSA compliant plane/kit has the most "potential" to be the fastest in cruise mode at around the 10,000ft sevice ceiling allowed in the class. Keep in mind that I am only a dedicated student here, not one of the masters(Orion, etc.)

I'd look for several things:

1- A plane that was designed to fly faster in the first place, such as many of the european light planes that were neutered to slow them down to fit the max continuous at 75% power rule. The simplist being swapping props to a lower pitched climb prop. It's easy to kill as much speed as desired to fit into LSA's rules this way, the more speed killed off, the better the climb rate, not a terrible trade. Just swap back to their european rule optimized prop, and there is your speed back. Just know that you would officially be skirting the regs by doing so because your 75% max continuous speed would now be too fast.

2- A plane with the cleanest aerodynamics. The best of which is generally full composite planes which do not need to be design restricted by the inability to handle compound curves for the majority of the plane. Plus, composite planes typically have much smoother surfaces, no rivet dimples and reduces chance of any type of oil canning. Cleaner planes have a much easier time getting good cruise speed with modest HP.

3- A low drag cooling system.

4- Using an engine that can be safely tuned to operate at an rpm higher than the model's 75% max continuous rating. Or perhaps a non certified engine such as a corvair, which do not have an official 75% rating as far as I know. This falls into something of a grey area(EX: claim an artificially low 75% 2700rpm, but operate at 3200rpm cruise in reality). Another option is to use a turbocharged engine, which will not loose the typical 25% power at 10,000ft, but will retain full power or more. This would mean a sizable diference between low and higher altutude performance.

Are you looking for fully compliant ways, "grey area" ways, or flat skirting the rules ways to cruise as fast as possible?

PS. I know of atleast one Sonex with a modified corvair pushing 180mph on the top end and about 160 at cruise.

George
 

mcjon77

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You never mentioned the fastest LSA. How's the Sonex's speed?
The numbers qouted on the Sonex website are pretty accurate (some say conservative). A Jabiru 3300 powered Sonex will usually go high170's-low 180's max speed straight and level. If you have a Jabiru 3300, at 8,000 and 2850rpm (the max continuous recommended by jabiru), folks are seeing around 150mph+ true. However many folks fly the jabiru at higher rpms at that altitude. WOT at 8,000 is usually 3050-3100rpm. This rpm is beyond the engine manufacturers recommended max continous, but people have flown it at this rate with no noticable problems. At that rpm and altitude, people are seeing 170mph true (or better), just like that factory states.

My bet is you would get similar numbers if you put the same engine in a Sonerai IILorIILS (another plane which could qualify for light sport).
 

pilot50

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The top speed of LSA are all restricted to <120 knots. If you want to go faster without needing a medical, you can get a glider license (no medical required) and fly a motorglider. The Pipistrel Virus motor-glider has a 121.5 kt cruise, 129.5 kt top speed and 800 sm range.
There doesn't seem to be a separate glider license anymore. It's a category on a sport pilot, recreational pilot or private pilot license. So, a medical seems to be required to fly anything with Vh > 120 kt.

jh
 

pilot50

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There doesn't seem to be a separate glider license anymore. It's a category on a sport pilot, recreational pilot or private pilot license. So, a medical seems to be required to fly anything with Vh > 120 kt.

jh
Oops, I was only half right. There is no "glider license", but the current FAR says: (b) Operations not requiring a medical certificate. A person is not required to hold a valid medical certificate—
(1) When exercising the privileges of a student pilot certificate while seeking—
...
(ii) A pilot certificate with a glider category rating or balloon class rating;
...
(3) When exercising the privileges of a pilot certificate with a glider category or balloon class rating;
 

lr27

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Ok, what's the fastest balloon? ;-p

Motorglider at highest permitted altitude seems like the loophole, but I don't know how high that is. Is it really worth it to get a few extra knots?
 

rpellicciotti

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Feb 10, 2005
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Location
Memphis, TN
Yes, one S-LSA airplane that is fast is the Sting. I fly these airplanes regularly and at higher altitudes I see TAS of around 130 knots. If you can get a little tailwind, 150 knots is no problem.

Sting S3 & Sirius: Light Sport Aircraft

I have seen some references to "75% power". There is nothing in the LSA rules that state Maximum Continuous Power as 75% power. If a S-LSA manufacturer wants to set the maximum continuous power at 100% or any other number, they can. The above mentioned Sting with the supplied prop will do 120 KIAS at sea level on a standard day at 5800 rpm.
 

mcjon77

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...I have seen some references to "75% power". There is nothing in the LSA rules that state Maximum Continuous Power as 75% power. If a S-LSA manufacturer wants to set the maximum continuous power at 100% or any other number, they can. The above mentioned Sting with the supplied prop will do 120 KIAS at sea level on a standard day at 5800 rpm.
Actually, it is the engine manufacturer that sets max continuous power, not the LSA manufacturer. Rotax 912s have a max continous power of about 90% (e.g. the 912S has a max power of 100hp with a max continous of 90hp).


Infact, power is not the best term. The FAA rules deal with calibrated airspeed, at sea level, at max continuous RPM. It is one of the reasons why the Sonex with a Jabiru 3300 is only LSA compliant if one of the earlier 3300A engines are used (max continous RPM of 2750rpm) or the current 3300L is used (max continous RPM of 2850rpm). A current 3300A engine, with a max continous RPM of 3150, will result in a CAS that is above 120kts, unless a different prop is used.
 

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