An 1800 lb LSA?

Talk about airplanes! At last count, there are 39 (and growing) FAA certificated S-LSA (special light sport aircraft). These are factory-built ready to fly airplanes. If you can't afford a factory-built LSA, consider buying an E-LSA kit (experimental LSA - up to 99% complete).

Moderator: drseti

Cluemeister
Posts: 329
Joined: Mon Nov 02, 2015 8:20 pm

An 1800 lb LSA?

Postby Cluemeister » Thu Jun 23, 2016 8:33 pm


User avatar
MrMorden
Posts: 1733
Joined: Fri Aug 17, 2012 7:28 am
Location: Athens, GA

Re: An 1800 lb LSA?

Postby MrMorden » Fri Jun 24, 2016 9:04 am

the FAA said repeatedly and emphatically that any weight beyond 1320lb, and any stall speed above 45kt, would compromise safety...

Unless of course, your design is "cool" like an Icon or Terrafugia. And maybe greasing some palms along the way might help too. :roll:
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

User avatar
drseti
Posts: 5220
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: An 1800 lb LSA?

Postby drseti » Fri Jun 24, 2016 10:39 am

Not only did they raise the max gross weight for the Terrafugia Transition, FAA also relaxed the stall speed restriction. The result is a doubling of the kinetic energy that must be dissipated in a takeoff or landing accident.

Here are the numbers for an aircraft that complies with the LSA rule:

KE_lsa.jpg
KE_lsa.jpg (24.23 KiB) Viewed 2130 times


And here they are for the Terrafugia Transition:

KE_terrafugia.jpg
KE_terrafugia.jpg (24.97 KiB) Viewed 2130 times


Doubling the KE means that the fatality rate in the event of an accident is also essentially doubled.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
fly@AvSport.org
http://AvSport.org
http://facebook.com/SportFlying

Cluemeister
Posts: 329
Joined: Mon Nov 02, 2015 8:20 pm

Re: An 1800 lb LSA?

Postby Cluemeister » Fri Jun 24, 2016 11:18 am

MrMorden wrote:the FAA said repeatedly and emphatically that any weight beyond 1320lb, and any stall speed above 45kt, would compromise safety...

Unless of course, your design is "cool" like an Icon or Terrafugia. And maybe greasing some palms along the way might help too. :roll:


I am shocked, shocked to find gambling at this establishment!

Cluemeister
Posts: 329
Joined: Mon Nov 02, 2015 8:20 pm

Re: An 1800 lb LSA?

Postby Cluemeister » Fri Jun 24, 2016 11:20 am

Maybe we need a new category:

Not-so-Light Sport Aircraft

User avatar
MrMorden
Posts: 1733
Joined: Fri Aug 17, 2012 7:28 am
Location: Athens, GA

Re: An 1800 lb LSA?

Postby MrMorden » Fri Jun 24, 2016 12:09 pm

eyeflygps wrote:
drseti wrote:
Doubling the KE means that the fatality rate in the event of an accident is also essentially doubled.
Unless the plane is structurally more sound to withstand the additional KE.


But that is *exactly* the argument rejected by the FAA when weights limits above 1320lb were discussed! EAA and others argued higher weight allowed more crash-resistant structure, and the FAA roundly rejected that argument because of the kinetic energy math, as Paul posted.

The FAA wants to make whatever argument they need that suits the situation they are trying to justify. There is really no other explanation.
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

User avatar
MrMorden
Posts: 1733
Joined: Fri Aug 17, 2012 7:28 am
Location: Athens, GA

Re: An 1800 lb LSA?

Postby MrMorden » Fri Jun 24, 2016 12:10 pm

Cluemeister wrote:Maybe we need a new category:

Not-so-Light Sport Aircraft


Why not? We used to have "fat ultralights", now we can have "chubby LSA"...
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

MackAttack
Posts: 145
Joined: Wed Apr 20, 2016 10:22 pm

Re: An 1800 lb LSA?

Postby MackAttack » Fri Jun 24, 2016 1:00 pm

As long as nobody makes comments about chubby sport pilots we're all going to get along fine ... 8)

I find this all to be completely ridiculous; there is simply no safety-related justification for this or the Icon decision. Pure lobbying muscle ... and frankly, it continues to undercut the whole 1320-lb weight limit in the first instance. Really bothers me.

What about those manufacturers that moved heaven and earth to design a great airplane that meets the limit? Honestly, what's the point for them? All this winking and nodding going on ...

Almost as bad as Brexit ... *laughing*

Rant complete.

Cheers!

User avatar
dstclair
Posts: 948
Joined: Thu Mar 06, 2008 11:23 am
Location: Allen, TX

Re: An 1800 lb LSA?

Postby dstclair » Fri Jun 24, 2016 2:20 pm

But that is *exactly* the argument rejected by the FAA when weights limits above 1320lb were discussed! EAA and others argued higher weight allowed more crash-resistant structure, and the FAA roundly rejected that argument because of the kinetic energy math, as Paul posted.

I have no idea what thought process went into the exception but it is interesting that the Transition is equipped with airbags and "automotive crash safety features". Perhaps they really did make a more crash tolerant structure and that did factor into the approval. Time will tell.
dave

User avatar
cynamonb
Posts: 14
Joined: Sat Jun 11, 2016 9:14 am
Location: FXE 97FL 1A5

Re: An 1800 lb LSA?

Postby cynamonb » Fri Jun 24, 2016 3:11 pm

Even if the aircraft is more structurally sound as some suggest, the pilot is not. There is a limit to how much deceleration the human body can withstand.

User avatar
drseti
Posts: 5220
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: An 1800 lb LSA?

Postby drseti » Fri Jun 24, 2016 9:30 pm

But we're not comparing LSA to "most other sircraft." We're comparing them to Part 103 ultralights. Remember, adding those to the regulatory fold was FAA's whole reason for creating SP and LSA rules in the first place.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
fly@AvSport.org
http://AvSport.org
http://facebook.com/SportFlying

User avatar
dstclair
Posts: 948
Joined: Thu Mar 06, 2008 11:23 am
Location: Allen, TX

Re: An 1800 lb LSA?

Postby dstclair » Sat Jun 25, 2016 9:48 am

This was my point as well. Automobile designs are subject to a barrage of crash tests (http://www.iihs.org/iihs/ratings/techni ... -protocols) which, presumably, the Transition must pass. If so, this plane may be safer than a typically LSA and this was considered in the application. Consider the results on the driver of the 40mph direct crash in a 2016 Chevy vs 1956 Chevy. The driver walks away in 2016 and probably does not in 1956.
dave

User avatar
drseti
Posts: 5220
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: An 1800 lb LSA?

Postby drseti » Sat Jun 25, 2016 10:29 am

These exemptions may not have been arbitrary, but they're sure going to look arbitrary to those other manufacturers who have bent over backwards to comply with the adopted rules. I'm sure they would prefer a level playing field.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
fly@AvSport.org
http://AvSport.org
http://facebook.com/SportFlying

User avatar
dstclair
Posts: 948
Joined: Thu Mar 06, 2008 11:23 am
Location: Allen, TX

Re: An 1800 lb LSA?

Postby dstclair » Sat Jun 25, 2016 12:54 pm

Maybe if they come out with a revolutionary design, they can get an exception

Beat me to the punch. The current LSA manufacturers can cry foul with Icon and Terrafugia or they can look on the positive side and take it as a challenge. They could analyze why Icon and Terrafugia were granted exceptions and see if the specific improvements can be incorporated into their design. Demonstrate the advances to the FAA and get an exception for the improvements that they can implement. If they were really altruistic they could make a case that a specific safety wizbang was good for the entire LSA industry and get an exception for XYZ lbs and ABC stall speed. Then a very bright engineer could come up with an implementation that was less than the allowed weight exception thus increasing useful load.

Remember, the FAA stated many years ago when they granted the Icon exception that they were open to increasing the LSA weight with NEW innovations and not with technology/designs that were available when the standard was approved.

And, yes, I do know that many of us are suspect of Icon and Terrafugia's advances but they were able to convince the FAA, and that's what matters.
dave

HAPPYDAN
Posts: 261
Joined: Mon Mar 16, 2015 11:49 am

Re: An 1800 lb LSA?

Postby HAPPYDAN » Sat Jun 25, 2016 1:26 pm

I think the point is moot. Since WWII, others have tried to build something like a flying car, with limited success and financial failure. It seems, as it were, cars don't fly too well and airplanes make poor cars. But on the flip side, without failure there could be no success. Maybe someday.....


Return to “Light Sport Aircraft”

Who is online

Users browsing this forum: Google Adsense [Bot] and 3 guests