LSA speed limit - does it really apply only at the sea level?

HelloWorld

Filing Flight Plan
Joined
Dec 19, 2013
Messages
10
Location
Boise, ID
Display Name

Display name:
Hello, world!
According to Sonex Aircraft, to be certified as LSA, a plane needs to be slow only at the sea level. Therefore there is no restriction on speed at higher altitudes. (See the link below.) In fact, this seems to be one of the selling points for Sonex.

http://www.sonexaircraft.com/sportpilot/qualify.html

Is this legit? If so, then why aren't all other LSA builders also use this 'loophole?' Engine makers could design engines that are optimized at low pressure / high altitude condition so that the power output is low only at the sea level, and voila, you have high performance planes that still certify as LSA.

If this is true, why aren't other LSA builders following the suit? Was this not widely known, or the builders afraid of the wrath of FAA?
 
According to Sonex Aircraft, to be certified as LSA, a plane needs to be slow only at the sea level. Therefore there is no restriction on speed at higher altitudes. (See the link below.) In fact, this seems to be one of the selling points for Sonex.

http://www.sonexaircraft.com/sportpilot/qualify.html

Is this legit? If so, then why aren't all other LSA builders also use this 'loophole?' Engine makers could design engines that are optimized at low pressure / high altitude condition so that the power output is low only at the sea level, and voila, you have high performance planes that still certify as LSA.

If this is true, why aren't other LSA builders following the suit? Was this not widely known, or the builders afraid of the wrath of FAA?

That's not the intent of the rule. 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.

Dan
 
If this is true, why aren't other LSA builders following the suit? Was this not widely known, or the builders afraid of the wrath of FAA?
Not sure I share the premise of the question. Every faster LSA is like that, including the market leader CTLS. In fact CTLS is even marginally faster than Sonex with 120 hp Jabiru thanks to being more slippery and having reflex flaps. I would expect no less from an airplane that costs 3 times more :)
 
This why many have suggested using turbo normalized engines in LSAs. At sea level, they would do the prescribed 120 kts, but as they climbed higher and higher, they would go faster and faster. I don't think there are any this way though.
 
Flight Design sell a CTLS with 914t, although not in U.S.. That thing busts 120 kts limit even at sea level :)
 
This why many have suggested using turbo normalized engines in LSAs. At sea level, they would do the prescribed 120 kts, but as they climbed higher and higher, they would go faster and faster. I don't think there are any this way though.

Sonex is working on a turbo for their aero conversions VeeDub engine
 
There has got to be somebody building an RV-12 with a turbo Rotax somewhere.
 
RV-12 needs only a prop change to go significantly faster. CTLS is fast but it also has some VERY expensive continuing maintenance costs arbitrarily imposed by the manufacturer.
 
Didn't the Carbon Cub do an end run around his with a level flight RPM restriction?
 
RV-12 needs only a prop change to go significantly faster. CTLS is fast but it also has some VERY expensive continuing maintenance costs arbitrarily imposed by the manufacturer.

The one I built and flew was slightly faster than average because I filled the rivets, but only 2-3 knots. Its only 100 HP so not much will change by changing the prop. ;)
 
Prop makes a big difference. My CTSW would only hit about 108kt at max continuous power when I got it...after a prop re-pitch to make it less coarse, I now see 120-122kt at max continuous (5500rpm). It climbs better now too. The reason is the Rotax makes much of its power at high RPMs, and with a coarse prop you can never get to the higher RPMs and thus are really not making near full power. Other CT owners have had similar results, the factory settings are just too coarse.
 
RV-12 needs only a prop change to go significantly faster. CTLS is fast but it also has some VERY expensive continuing maintenance costs arbitrarily imposed by the manufacturer.

Elaborate please? The only such maintenance item I can think of is that at 1000 hours the Neuform has to come off for factory overhaul, costs about $1000. Most owners that get to that point simply switch to a Sensenich prop that does not require the overhauls, problem solved for an additional $1500.

Most other recurring maintenance is Rotax related, and will hit the RV just as much as the CT. There are not a lot of recurring airframe items. I think I have to call BS on this.
 
Didn't the Carbon Cub do an end run around his with a level flight RPM restriction?

Sonex does that too with the Jabiru 3300 engine. The 3300 IIRC has a max RPM limit of 3000, but the one installed in the Sonex is a 3300A with an RPM limit in continuous operation of 2850rpm. The only difference between a 3300 and a 3300A is the data plate, and Jabiru will send you the data plate to switch in either direction at your request. So a big wink and nod there too...
 
RV-12 needs only a prop change to go significantly faster.

Maybe, but if this is true, then the RV-12 can no longer be operated as a LSA because it violates the speed limit at sea level. The turbo is a means of going faster, complying with the law and continuing operation under the LSA rules.
 
Maybe, but if this is true, then the RV-12 can no longer be operated as a LSA because it violates the speed limit at sea level. The turbo is a means of going faster, complying with the law and continuing operation under the LSA rules.

What is the difference.... Either way you will be pushing the intent of the speed rule..

Best thing to is to just do it and not say a word....;):wink2:
 
Exactly. :yes:

We are the only country that I know of with a speed restriction, and we were one of the last to implement sport pilot.
For crikes sake man, can you imagine the ego hit if LSA's went faster then Mooney's and Bo's?
Oh the crying and whining, would be funny.
 
The speed restriction is stupid. When I was looking at lsa I asked could I get more speed on a CTls if I could go to neg 12 on the flaps. Was told it would take the removal of one pin. If lsa was IFR ,I would have one.
 
One's legal, the other is not. The illegal prop goes a little faster, the legal turbo goes a lot faster.

Agreed............. But...

The FAA in their infinate wisdom should have anticipated the advantage of turbo-normalizing a LSA and its potential speed advantage up high and written the rules differently... IMHO..:idea:
 
The LSA speed limit is stupid and a detriment to development.

Development of what? What is the point of any of the restrictions? What is the point of LSA? With any luck, the driver's license medical will become a reality and the whole LSA segment will be moot.
 
Agreed............. But...

The FAA in their infinate wisdom should have anticipated the advantage of turbo-normalizing a LSA and its potential speed advantage up high and written the rules differently... IMHO..:idea:

I personally think they should have eliminated the top speed, but maintained a very low stall speed requirement. Going fast while maintaining a low stall speed isn't easy to do. For the most part, this alone would govern the top speed. However, it very well could have led to some really clever airframe designs.
 
I personally think they should have eliminated the top speed, but maintained a very low stall speed requirement. Going fast while maintaining a low stall speed isn't easy to do. For the most part, this alone would govern the top speed. However, it very well could have led to some really clever airframe designs.

+1
Good point
 
I personally think they should have eliminated the top speed, but maintained a very low stall speed requirement. Going fast while maintaining a low stall speed isn't easy to do. For the most part, this alone would govern the top speed. However, it very well could have led to some really clever airframe designs.


Yup.... Give the masses a hurdle and you will get progress.... Happens in racing on a daily basis.... Rules are the mother of invention ya know..:yes:;)
 
If lsa was IFR, I would have one.
The Tecnam Sierra is IFR in Europe. It has no vacuum system, but has standby alternator and all the overpriced gauges. Buy one as E-LSA and voila. Your move.
 
Elaborate please? The only such maintenance item I can think of is that at 1000 hours the Neuform has to come off for factory overhaul, costs about $1000. Most owners that get to that point simply switch to a Sensenich prop that does not require the overhauls, problem solved for an additional $1500.

Most other recurring maintenance is Rotax related, and will hit the RV just as much as the CT. There are not a lot of recurring airframe items. I think I have to call BS on this.

You can call BS all you want but from a friend of mine who is a Light Sport Mechanic for school that operated CT's here's a few reasons why they do not anymore -

All CT's are required to have 100 hour inspections and most that we service run around $1500-$3500 per inspection based on make and model. Any paint chipping requires a full paint strip and re paint including around the front windows the last one we did cost the customer $25k. Any engine work other then oil changes almost guarantees the engine having to be removed a 12 hour min charge due to the engine sitting under the panel so to speak. The rudder pedals are almost always bent to some degree the cost for us to make them like new is $500 per set this leads to the point of if you sit in one and attempt to work the rudder pedals without forward motion the pedal will bend :). The brakes are on a center pull handle and makes ease for a quick pull that always flat spots the tires for early replacement and we always have to rebuild the master cylinder. Gear most will crack under a moderate hard landing and this runs around $8K for new legs. Seats- if you try to adjust the seat to size while sitting in it you have just paid for new carbon seat backs, cracks at the base every time cost $250 to fix. Engine mount we just replaced one from a few hard landings $5K just for the parts.

So yeah, go ahead a call BS but that looks pretty expensive to me.
 
Any paint chipping requires a full paint strip and re paint including around the front windows the last one we did cost the customer $25k.

Eh? If there is one paint chip, maybe the size of a pea or a dime, the whole plane is paint stripped and repainted? I'd like to see the aircraft mfg justification for that requirement.
 
You can call BS all you want but from a friend of mine who is a Light Sport Mechanic for school that operated CT's here's a few reasons why they do not anymore -

All CT's are required to have 100 hour inspections and most that we service run around $1500-$3500 per inspection based on make and model. Any paint chipping requires a full paint strip and re paint including around the front windows the last one we did cost the customer $25k. Any engine work other then oil changes almost guarantees the engine having to be removed a 12 hour min charge due to the engine sitting under the panel so to speak. The rudder pedals are almost always bent to some degree the cost for us to make them like new is $500 per set this leads to the point of if you sit in one and attempt to work the rudder pedals without forward motion the pedal will bend :). The brakes are on a center pull handle and makes ease for a quick pull that always flat spots the tires for early replacement and we always have to rebuild the master cylinder. Gear most will crack under a moderate hard landing and this runs around $8K for new legs. Seats- if you try to adjust the seat to size while sitting in it you have just paid for new carbon seat backs, cracks at the base every time cost $250 to fix. Engine mount we just replaced one from a few hard landings $5K just for the parts.

So yeah, go ahead a call BS but that looks pretty expensive to me.

I'm calling BS because you are talking BS. The 100 hour inspection is a ROTAX requirement, it applies to almost every LSA in the fleet. Most owners combine it with the annual, just do both when either one is due, both are usually done for less than $1000 unless squawks are found, then like any airplane it can go up from there.

Most CTs I have seen have paint chips, none have required a $25k repaint. I know of a bird strike on one CT that required replacement of the windshield and two carbon fiber panels, all structural components. Cost including repaint of the affected areas was about $10k.

The tires and brakes are a weak spot, because there is too much camber in the wheels causing fast tire wear and the Italian brake cylinder is not great. Both problems are fixed permanently by replacing with Matco brakes, costs $900. Since 2010 all CTs come with the Matcos.

The seats are designed to be adjusted on the ground, not in flight. The POH says so. They are fiberglass, not carbon. You can break anything if you use it wrong.

Yeah, if you botch a landing you can buy a new engine mount or gear leg. Just like any other tricycle airplane. Is it really a criticism that the airplane can be bent?? How much do you think a new Cessna, Sportcruiser, or Piper engine mount or gear will cost you? BTW, CT gear was beefed up in 2006, and even the old gear doesn't break unless you break it. Your argument is specious.

The engine sits nowhere near the panel, stood off from a flat firewall, most maintenance is easily done with the engine in place.

Sorry, "I know a guy who said..." Is not really working out for you. I own and operate a CT, and I'm telling you your anecdotes are either completely wrong or misleading. Every airframe has quirks or areas that are not ideal, but flight Design has been quick to address any it finds, and any failings are as cheap to correct as any other LSA, and much cheaper than most certified birds. And I burn 4-5gph of mogas, so I save a ton on fuel as well.
 
Last edited:
Eh? If there is one paint chip, maybe the size of a pea or a dime, the whole plane is paint stripped and repainted? I'd like to see the aircraft mfg justification for that requirement.

It doesn't exist, it's a lie.
 
Meanwhile, a local flight school that was flying Remos GX for about 3 years found it so successful that they bought another (GX is virtually identical to CTLS from the outside and inside, but it's not as fast due to strut-braced wing and no reflex flaps). They produced a number of Private and Sport pilots in that GX and flew more than 1000 hours -- I know because there was some kind of major maintenance at 1000 hours.

A crusty old Cessna Pilot Center may not be able to make a business out of training in LSAs, but it's not a law of nature.

BTW, rumors that Art was mongering reminded me that GX did indeed have an issue with uneven tire wear, although not flat-spotting. Apparently the shape of the cowl makes many renters to land in a slight right crab, so left tire gets worn out first. A simple workaround is to swap tires from side to side midway. Nonetheless it takes some attention to force people to seek centerline by looking at something other than cowling.
 
Last edited:
My Dad has a Remos GX and it will run right at the 120kt limit at 5000 rpm cruise. Great airplane and I love to fly it when I go down to SoCal. In fact I will be down there Friday. Don
 
I frequent a CT Forum.

My impression is that CT's are neither particularly expensive nor particularly cheap to maintain.

About in line with other LSA's, which overall seem less expensive than certified.

I'm happy with my ROTAX-powered Sky Arrow, but a CT would be on my short list were I looking to replace it. The nosebleed price of a new one ($160k+ :yikes:) would have me looking at a well preserved used example, as Andy did.

The engine "sitting under the panel" is patently untrue, as can be seen in any photo if one cared to look (found in about 15 seconds via Google image search).

IMG_4906.JPG
 
Last edited:
That's an interesting picture, Eddie...I've never seen a 912 with red valve covers. The 100 hp 912ULS has green covers, the 80hp 912UL has black covers. I wonder if that's a 912S or some other variant...?

Good pic though, very representative of CT engine access.
 
That's an interesting picture, Eddie...I've never seen a 912 with red valve covers. The 100 hp 912ULS has green covers, the 80hp 912UL has black covers. I wonder if that's a 912S or some other variant...?

Good pic though, very representative of CT engine access.

It's the turbocharged version. Follow the red scat tubing and you will see the compressor scroll. The duct to the intake goes up to the plenum on top.
 
It's the turbocharged version. Follow the red scat tubing and you will see the compressor scroll. The duct to the intake goes up to the plenum on top.

Ah, good catch...I have never seen a CT with a 914 before!
 
I think too the 100 hour inspection requirement besides being a Rotax thing is a requirement for any aircraft in a flight school for hire, unless I am mistaken?

Carl
 
I'm happy with my ROTAX-powered Sky Arrow, but a CT would be on my short list were I looking to replace it. The nosebleed price of a new one ($160k+ :yikes:) would have me looking at a well preserved used example, as Andy did.

Nooooo! Please don't ever replace a Sky Arrow with a CT. The Sky Arrow is so much cooler!! Too bad they don't offer a Sky Arrow on floats... do they?
 
Back
Top