and the difference you keep on interchanging max cruise and cruise in various posts... they are not the same... I originally posted with regard to the statement that cruise (which is not max cruise) was 120Kt...
Enough.
John]
On 2/27/2012 3:22 PM, Peter Walker wrote:
Hello
if it is set to the specification its legal That is 120 knots at sea level at the aircraft manufacturers maximum continuous power setting That is the manufacturers specified maximum cruise It doesnt specify any speed at at any other altitude or power setting No one is interested in pinging a plane that meets the specification that goes faster at altitudeThe Cubcrafters Supacub is rated at its 120 knots way under the engines manufacturers continuous power and its legal
Peter
From: UltraJohn <japrice@mindspring.com>
To: Sport_Aircraft@yahoogroups.com
Sent: Tuesday, February 28, 2012 4:22 AM
Subject: Re: Light-Sport Aircraft Yahoo group Re: Cruising speed
The point from my original reply to the original post is that if he set his aircraft up for CRUISE of 120Kt on a standard day, then basically his aircraft was illegal.
John
On 2/27/2012 8:41 AM, James Bair wrote:So? I'm missing the point of this entire thread. It's a definition. A standard day at sea level is a mathematical standard from which calculations can start so everyone is operating on the same page. Would you prefer they use 1,000'? Then we would hear someone in Colorado saying it's impossible for him to get there. No, it isn't. It's a math standard, just as you say, and calcs run from that standard. All demonstrable on a whiz wheel. BTW, the std temp is 59F (15C), not 72 that someone mentioned.JimFrom: Lyle CoxSent: Sunday, February 26, 2012 10:50 PMSubject: RE: Light-Sport Aircraft Yahoo group Re: Cruising speedSTILL…..it is an "arrived at " number….it's a mathematical specification. I agree it is a standard, to which the aircraft must adhere to, but it is……not a truly demonstrable specification, because those perfect conditions of "sea level and a standard day"….are impossible.From: Sport_Aircraft@yahoogroups.com [mailto:Sport_Aircraft@yahoogroups.com] On Behalf Of Peter Walker
Sent: Sunday, February 26, 2012 9:44 PM
To: Sport_Aircraft@yahoogroups.com
Subject: Re: Light-Sport Aircraft Yahoo group Re: Cruising speedHelloCruise is set at the aircraft manufacturers specified MAXIMUM continuous power at sea level in straight and level flight What that gives at 5000 feet is not an issue1 Technically there are places below sea level Dead Sea is the lowest about 413metres 1400 feetDeath valley is no 8 at 86 metres 260 feet below sea level Conversions are from the top of my head2 The physics are well enough understood to easily calculate it But for practical puposes you need a barometer reading and a temperature to meet the specificatision Density altitude is the recognised termPeterFrom: Lyle Cox <LyleCox@funaerosports.com>
To: Sport_Aircraft@yahoogroups.com
Sent: Monday, February 27, 2012 3:11 PM
Subject: RE: Light-Sport Aircraft Yahoo group Re: Cruising speedYep….and then you would be illegal. Of course, the number is somewhat of a "calculated number" since two conditions of the rule don't really exist….1. Can't really fly at sea level, since you wouldn't be flying, you'd just be taxiing REALLY fast2. Does a standard day ever really exist?From: Sport_Aircraft@yahoogroups.com [mailto:Sport_Aircraft@yahoogroups.com] On Behalf Of UltraJohn
Sent: Sunday, February 26, 2012 9:04 PM
To: Sport_Aircraft@yahoogroups.com
Subject: Re: Light-Sport Aircraft Yahoo group Re: Cruising speedExactly, if you set your plane so that cruise (not max speed) to 120Kt on a standard day at sea level, then when you run it at max continuous power you WILL be going faster than 120Kt on a standard day at sea level
On 2/26/2012 10:50 PM, Lyle Cox wrote:Actually….no….it says "maximum continuous power", which has nothing to do with 75% power cruise settings. For example, I frequently run my Cherokee at max continuous power up here in Colorado, which actually is around 68% power, if compared to sea level and a standard day.From: Sport_Aircraft@yahoogroups.com [mailto:Sport_Aircraft@yahoogroups.com] On Behalf Of Lyle Cox
Sent: Sunday, February 26, 2012 8:47 PM
To: Sport_Aircraft@yahoogroups.com
Subject: RE: Light-Sport Aircraft Yahoo group Re: Cruising speedThe rule says. Max cruise power…..etc…..not 75%From: Sport_Aircraft@yahoogroups.com [mailto:Sport_Aircraft@yahoogroups.com] On Behalf Of UltraJohn
Sent: Sunday, February 26, 2012 8:36 PM
To: Sport_Aircraft@yahoogroups.com
Subject: Re: Light-Sport Aircraft Yahoo group Re: Cruising speedHow so? you said yourself that you set cruise at 120Kt on standard day.
Cruise normally is 75% max power in just about any piston engine prop plane existing.
So If you set the cruise as you specified then the speed at Max continuous power would be something in excess of the legal 120Kt.
It doesn't matter if you maintain a slower speed, if it is capable as set up of exceeding 120kt then it is not legal lsa/sport pilot...
John
On 2/26/2012 9:34 PM, Peter Walker wrote:HelloHow so? Your are meeting the specification If you go faster at altitude its still legal as long as you keep the plane to spec and observe max continuous settings
PeterFrom: UltraJohn mailto:japrice@mindspring.com
To: Sport_Aircraft@yahoogroups.com
Cc: Peter Walker mailto:peterwalker58@yahoo.com
Sent: Monday, February 27, 2012 12:16 PM
Subject: Re: Light-Sport Aircraft Yahoo group Re: Cruising speedLSA rules dictate that the MAX Speed with Max continuous power is no greater than 120kt (with standard conditions (29.92hg, 72degrees Sea Level I think)...
If you have your cruise speed set to 120kt then most likely you are running illegally.
John
On 2/26/2012 3:14 PM, Peter Walker wrote:HelloThe cruise speed is set at 120knots at sea level on a standard dayPeterFrom: rotax2you mailto:rotax2you@yahoo.com
To: Sport_Aircraft@yahoogroups.com
Sent: Monday, February 27, 2012 2:15 AM
Subject: Light-Sport Aircraft Yahoo group Re: Cruising speedThere is a problem in your numbers. The 912ULS, 100hp at take off 5800, has a max continuous of 5500 or 96 hp. At altitude the propeller unload proportionate to the air density that more or less matches the power loss. The aircraft climbs slower but will go faster in level flight.
The engine maintains the 5500, but you are correct the power drops. The rule, set by the FAA, is for the aircraft not to exceed 120 knots in standard conditions. What is does at altitude is not a factor.
--- In mailto:Sport_Aircraft%40yahoogroups.com, "Lyle Cox" mailto:LyleCox@... wrote:
>
> I think its 120 KIAS at sea level, continuous maximum cruise speed.
>
> From: mailto:Sport_Aircraft%40yahoogroups.com [mailto:mailto:Sport_Aircraft%40yahoogroups.com]
> On Behalf Of Bill C
> Sent: Tuesday, March 09, 2010 6:01 PM
> To: mailto:Sport_Aircraft%40yahoogroups.com
> Subject: Light-Sport Aircraft Yahoo group Re: Cruising speed
>
>
> Here is an interesting post to another group concerning engine specs and how
> they effect this:
>
> Re: Fastest Light Sport Airplane?
> 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 continuous 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
> continuous 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.
> Jon McDonald
> Building Sonex #1287
>
__._,_.___
Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___
No comments:
Post a Comment