Light Sport Speed Limits

Stephen Poole

Stephen Poole

Pre-takeoff checklist
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Jun 12, 2018
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369
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Birmingham, Alabama
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Professor31
I wasn't sure where to post this. I've been learning, studyin', lurking here, reading everything I can get my hands on. I'm going to go for my Sport Pilot license shortly.

The Rules say that the speed is limited to 120 Knots on an LSA. OK, got that. But I've read comments here and in other forums that have me confused. Supposedly, that limit is defined at sea level. I ain't an expert, but I assume that I will not be flying at sea level (not unless I want to excite a lot of people and make the news.) What does that mean? The Rules also say that this 120 Knots is the "maximum speed in level flight."

Also, just to name one example, the Pipestrel Virus is sold in the US as a Light Sport, but has a top speed well above that (about 150 knots, as I recall). Do they put a governor on it? Are you on the honor system? Does a parachute pop out and slow you down? (OK, I'm kidding now.)

And what if someone isn't honorable? As a practical matter, what will happen if, say, you're just tooling along in your LSA, with a Sport Pilot license, and decide to bump the throttle up to 130 or 135 knots? Will you get a ticket?

This stuff might be obvious to you, but I'm still larnin'. I've read the rules, read various interpretations of the rules, and I'm still scratching my head.

Thanks in advance.
 
Stephen Poole said:
The Rules say that the speed is limited to 120 Knots on an LSA. OK, got that. But I've read comments here and in other forums that have me confused. Supposedly, that limit is defined at sea level. I ain't an expert, but I assume that I will not be flying at sea level (not unless I want to excite a lot of people and make the news.) What does that mean? The Rules also say that this 120 Knots is the "maximum speed in level flight."
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The speed given is under standard atmospheric conditions, same as any other aircraft performance specification. The airplane might fly faster at altitude simply because the air is thinner and offers less drag, but engine output is also reduced for the same reason and the increase will be minimal but perfectly legal.

Stephen Poole said:
say, you're just tooling along in your LSA, with a Sport Pilot license, and decide to bump the throttle up to 130 or 135 knots? Will you get a ticket?
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Yes, you might get a citation issued mid-flight. :)
 
Stephen Poole said:
Also, just to name one example, the Pipestrel Virus is sold in the US as a Light Sport, but has a top speed well above that (about 150 knots, as I recall). Do they put a governor on it? Are you on the honor system? Does a parachute pop out and slow you down? (OK, I'm kidding now.)
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I don't know the particulars about the Pipistrel, but in general, I believe this is solved by limiting that max-continuous power in the airplane's operating limitations.
 
The 120 knot limit is a requirement of the aircraft, not the person flying it. If it can go faster than that in level flight at sea level under standard conditions, then it's not an LSA.
 
dmspilot said:
The 120 knot limit is a requirement of the aircraft, not the person flying it. If it can go faster than that in level flight at sea level under standard conditions, then it's not an LSA.
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Understood. Pipistrel apparently limits the speed for an aircraft sold as a US-LSA. But it would be very easy to remove that limitation, I suspect. Read their statement on the spec page for the Virus SW:

https://www.pipistrel-usa.com/virus-sw/

(By the way, completely off-topic, the biggest thing that would keep me away from this particular LSA is the name. Can you imagine telling everyone, "I have a Virus and I'm so proud of it!"??)
 
Oblivion said:
I'd love to be issued a Citation, but I'm sure I couldn't afford to park it, let alone operate it.
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I’d love to be issued one too, unfortunately my odds favor the type I don’t want to be issued.
 
The 120 KCAS limit is at sea level standard conditions, at max continuous power. I suspect that a manufacturer could set a MCP limitation that will meet the speed requirement (wink, wink, nudge, nudge).
 
Stephen Poole said:
(By the way, completely off-topic, the biggest thing that would keep me away from this particular LSA is the name. Can you imagine telling everyone, "I have a Virus and I'm so proud of it!"??)
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I think it's pronounced "vee-rus", but yeah, unfortunate choice of name.
 
SkyDog58 said:
You will learn that not all limitations are physical limitations but are regulatory or certification based.
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Certainly. Actually, I do understand that quite well, in my line of work (Radio Engineering, under the FCC). But again: what is the procedure? Some ATC sees that I'm way too fast and calls in a Law Dog to bust me once I land? For that matter, how do they know that I have a Sport Pilot license? I'm looking at real-world practicalities here.
 
Stephen Poole said:
Certainly. Actually, I do understand that quite well, in my line of work (Radio Engineering, under the FCC). But again: what is the procedure? Some ATC sees that I'm way too fast and calls in a Law Dog to bust me once I land? For that matter, how do they know that I have a Sport Pilot license? I'm looking at real-world practicalities here.
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ATC doesn’t even know who’s flying the plane. I’m a non instrument rated pilot flying with SP privileges and no medical, in an LSA with no IFR capable GPS... and I could file and fly IFR and no one would know any different unless I got ramp checked or someone turned me in. Or more likely when it was discovered during the accident investigation. Pretty sure there’s no one checking this stuff. Fortunately most people (myself most definitely included) are more law abiding and less stupid than that.
 
Stephen Poole said:
Certainly. Actually, I do understand that quite well, in my line of work (Radio Engineering, under the FCC). But again: what is the procedure? Some ATC sees that I'm way too fast and calls in a Law Dog to bust me once I land?
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I answered this already; the pilot can't fly an LSA "too fast". The restriction is on the characteristics of the airplane, not on how it is flown.
 
Stephen Poole said:
Certainly. Actually, I do understand that quite well, in my line of work (Radio Engineering, under the FCC). But again: what is the procedure? Some ATC sees that I'm way too fast and calls in a Law Dog to bust me once I land? For that matter, how do they know that I have a Sport Pilot license? I'm looking at real-world practicalities here.
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Just keep your calibrated airspeed under 120 knots and you will be fine. ATC sees your ground speed, not your airspeed.
 
DaleB said:
I think it's pronounced "vee-rus", but yeah, unfortunate choice of name.
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But they had to print it right on the side of the plane! Right where everyone can see it: VIRUS. No, no, that won't do.

"Hey, everybody, there's a Virus coming!" "Look, an airborne Virus!"

No, just won't do at all.

It's a shame, too. I've been torn between the Tecnam P92 and the Pipistrel. The latter is considerably less expensive. Maybe I can put some tape over the name or something.
 
dmspilot said:
I answered this already; the pilot can't fly an LSA "too fast". The restriction is on the characteristics of the airplane, not on how it is flown.
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Umm ... yes. You did. Thanks. But suppose someone can change the restriction (as with the Pipistrel, aforementioned above and all that). In that case, yes, the pilot COULD fly the plane too fast.

I've also read reviews of LSAs (a Pipistrel and a Flight Design, as I recall) where the reviewer clearly said things like, "at altitude, at maximum RPM, we were able to get 131 knots at 6 gph." So whatever the manufacturers are doing to "restrict" the plane obviously isn't much of a restriction in some cases. :)
 
Stephen Poole said:
Certainly. Actually, I do understand that quite well, in my line of work (Radio Engineering, under the FCC). But again: what is the procedure? Some ATC sees that I'm way too fast and calls in a Law Dog to bust me once I land? For that matter, how do they know that I have a Sport Pilot license? I'm looking at real-world practicalities here.
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There's no limit on how fast you fly; there's only a limit on the speed that the plane is capable of achieving in level flight at sea level.

dmspilot said:
I answered this already; the pilot can't fly an LSA "too fast". The restriction is on the characteristics of the airplane, not on how it is flown.
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True. The only speeds you are not allowed to exceed in flight are ones that are listed as limitations in the POH. For example, the "never exceed speed," Vne, for a Skycatcher is 148 KIAS, or 143 KCAS, which is well above 120 knots.
 
ateamer said:
The 120 KCAS limit is at sea level standard conditions, at max continuous power. I suspect that a manufacturer could set a MCP limitation that will meet the speed requirement (wink, wink, nudge, nudge).
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I think you've caught my drift there. :)
 
Stephen Poole said:
Umm ... yes. You did. Thanks. But suppose someone can change the restriction (as with the Pipistrel, aforementioned above and all that). In that case, yes, the pilot COULD fly the plane too fast.

I've also read reviews of LSAs (a Pipistrel and a Flight Design, as I recall) where the reviewer clearly said things like, "at altitude, at maximum RPM, we were able to get 131 knots at 6 gph." So whatever the manufacturers are doing to "restrict" the plane obviously isn't much of a restriction in some cases. :)
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All you have to do to get an LSA to go faster than its level-flight design restriction is descend without pulling back the power.
 
ateamer said:
The 120 KCAS limit is at sea level standard conditions, at max continuous power. I suspect that a manufacturer could set a MCP limitation that will meet the speed requirement (wink, wink, nudge, nudge).
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Wot, something like hanging a 160 HP engine on a Cub clone and limiting the max RPM ... oh ... nevermind. What a crazy idea. It'd never work.
 
Stephen Poole said:
Umm ... yes. You did. Thanks. But suppose someone can change the restriction (as with the Pipistrel, aforementioned above and all that). In that case, yes, the pilot COULD fly the plane too fast.
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Unapproved alterations render the airplane unairworthy and it can't be flown at any speed.
 
um, if the thing only gets 120KCAS at sea level at MCP (whether by paper limit or actual physical engine output limit), you'll never get a faster KCAS at altitude. Sure, the true airspeed will increase 2% per 1k, but explain to me how an airplane with a NA engine and a fixed pitch prop gets a higher calibrated airspeed at altitude than at sea level.
 
hindsight2020 said:
um, if the thing only gets 120KCAS at sea level at MCP (whether by paper limit or actual physical engine output limit), you'll never get a faster KCAS at altitude. Sure, the true airspeed will increase 2% per 1k, but explain to me how an airplane with a NA engine and a fixed pitch prop gets a higher calibrated airspeed at altitude than at sea level.
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Where's the requirement for a naturally aspirated engine?
 
hindsight2020 said:
um, if the thing only gets 120KCAS at sea level at MCP (whether by paper limit or actual physical engine output limit), you'll never get a faster KCAS at altitude. Sure, the true airspeed will increase 2% per 1k, but explain to me how an airplane with a NA engine and a fixed pitch prop gets a higher calibrated airspeed at altitude than at sea level.
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Use an engine with a 2700 RPM redline and placard it for 2200 RPM MCP. Of course the pilot will obey that limitation.
 
ateamer said:
Use an engine with a 2700 RPM redline and placard it for 2200 RPM MCP. Of course the pilot will obey that limitation.
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I already addressed that. I said provided the limit is observed.
 
dmspilot said:
Unapproved alterations render the airplane unairworthy and it can't be flown at any speed.
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Only if the owner desired to retain the plane as a Special Light Sport. If he or she decides to relicense it as Experimental Light Sport, they can perform any modifications they choose. They do not have to prove that everything remains in the light sport definition, but obviously the FAA could challenge them on that if it's especially egregious.

Ron Wanttaja
 
wanttaja said:
Only if the owner desired to retain the plane as a Special Light Sport. If he or she decides to relicense it as Experimental Light Sport, they can perform any modifications they choose. They do not have to prove that everything remains in the light sport definition, but obviously the FAA could challenge them on that if it's especially egregious.

Ron Wanttaja
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The caveat being, anything excluded (variable pitch prop comes to mind) renders it a permanent lawn ornament... never legal to fly again. It can't even be flown as an EAB, since ELSA doesn't have a 51% amateur construction rule.
 
DaleB said:
ATC doesn’t even know who’s flying the plane. I’m a non instrument rated pilot flying with SP privileges and no medical, in an LSA with no IFR capable GPS... and I could file and fly IFR and no one would know any different unless I got ramp checked or someone turned me in. Or more likely when it was discovered during the accident investigation. Pretty sure there’s no one checking this stuff. Fortunately most people (myself most definitely included) are more law abiding and less stupid than that.
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Send me your address and I'll mail you a cookie. That was the answer I was looking for.

Like you, I AM NOT interested in breaking the law. But I was curious.
 
hindsight2020 said:
I don't know, I don't care enough about LSAs to look it up. Is there a turbo LSA out there?
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There are plenty. From what I've seen, most LSAs use Rotax, and they make some turbocharged engines. The latest Tecnam P2008T is turbocharged, as is the Sling.
 
wanttaja said:
Only if the owner desired to retain the plane as a Special Light Sport. If he or she decides to relicense it as Experimental Light Sport, they can perform any modifications they choose. Ron Wanttaja
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You beat me to it. I may be a novice-working-on-Newbee-status but I had already looked at the Rules for that, very carefully. My plan is to use that DAR guy in Georgia (forgot his name!) to move my plane from SLSA to ELSA, then take the course so that I can do my own maintenance. Not so much so that I can do my own repairs, but so that if I decide to add something to the panel, I can.

This does NOT mean that I'm stupid. I will still pay someone to do those things that I'm not comfortable with, especially at first (such as airframe integrity checks).
 
So, if I can fly an LSA any speed it’ll manage, I guess I can fly it with any gross weight it can manage.....
 
It’s indicated, and there have been known to be some tailwinds ;)
 
Salty said:
So, if I can fly an LSA any speed it’ll manage, I guess I can fly it with any gross weight it can manage.....
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That would be true if max gross weight were not published in the limitations section of the POH.
 
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