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  #1  
Old 09-29-2019, 07:53 AM
talon167 talon167 is offline
 
Join Date: Jan 2019
Location: Maryland
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Default MOSAIC - LSA/Sport Pilot Changes - Waiting vs Current RV12iS Adaptability

I am thinking about building an RV12iS, but I am hesitating because of the pending FAA MOSAIC changes to the Light Sport and Sport Pilot definitions.

Oshkosh '19 update from Dan Johnson (LAMA):
Latest Update on FAA’s Plan to Change Light-Sport Aircraft Regulations — July 2019.

I have two issues:
1. When - should I wait to build to take advantage of the changes?
2. RV12 adaptability - if I build an RV12iS now, what is the probability I can take advantage of MOSAIC changes prior to or shortly after completing the build? It may take me a couple of years to build.

When (source: linked article)
The FAA Reauthorization Act of 2018 includes a deadline of 2023 for implementing a key mandate that suggests the longest it should take. Once an NPRM is published, a comment period follows to hear from the public after which FAA needs time to address the concerns raised during that comment period. After closure of that comment period, the FAA has up to 16 months to publish the Final Rule.

What (speculation)
  • increased gross takeoff weight (via "power index")
  • increased Vh (via power index)
  • automated in-flight prop adjustment
  • 4 seat max, but still only 1 passenger max (in combo with other changes, permitting 4 seats will put a lot more legacy certified aircraft within the scope of LSA - maybe even a Van's non-RV12 model).
  • stall minimums - slight increase

Playing the waiting game
Waiting assumes:
  • It will happen. Based on the FAA's public comments and the groups that are giving input into the rule making (e.g., EAA, LAMA) the odds of the changes are extremely high. When is likely 2 to 3 years.
  • It will be meaningful. What the changes will be is very much up the air (sorry, couldn't resist). Although I love flying the RV12 I am renting, I really would like LSAs to add more weight without compromising performance for better crosswind handling. The current weight limit needlessly decreases safety.

PROS OF WAITING: Not locked into current rule limitations, resale value, increased weight = increased safety, more aircraft choices

CONS: May never happen, delay could be many years

Build now and Adapt Viable??
So this leads me to my question. If it will take me a couple of years to build an RV, LSA and Sport Pilot changes are likely occur during the tail end of the build or shortly after the build is complete

Will an RV12iS be able to take advantage of the changes via modification? Are competitor LSAs better suited for modification?

Questions:
  • Can the current RV12iS structurally use a Rotax 915iS?
  • With an upgraded engine such as the 135hp 915iS, can the current RV12iS structurally add hundreds of pounds of weight without too much of an issue. Fuel capacity may be the easiest to add to increase weight (e.g. is it viable to add wing tanks and make wings non-removable; increase fuselage fuel tank size)

Your thoughts on the current RV12iS's adaptability to the potential LSA/Sport Pilot changes - thanks!

Non-LSA side note: Among the most exciting things about MOSAIC was emphasized by the FAA acting commissioner at Oshkosh '19 - changes will include making it easier and less expensive for certified GA non-commercially used legacy aircraft to improve avionics (basically he said the current rules are unacceptable because they significantly impede improving GA safety with readily available tech - FAA flexibility would be offset by limitations on the updated aircraft's use - e.g., cannot be used commercially). Basically he indicated legacy certified will have the option to switch to experimental status for the purpose of avionics upgrades.

Last edited by talon167 : 09-29-2019 at 07:57 AM.
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  #2  
Old 09-29-2019, 10:41 AM
Flynfrfun Flynfrfun is offline
 
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If you are young enough that a 5yr wait doesn't matter then I say wait and see what happens. If you are up there in age probably better to build now and worry about the changes later. My .02
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  #3  
Old 09-29-2019, 12:33 PM
rocketman1988 rocketman1988 is offline
 
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Default Hmmm...

A government deadline...that's funny.

The only regret I have building my -10 is that I didn't start sooner.

Build now.
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  #4  
Old 09-29-2019, 01:41 PM
David Paule David Paule is offline
 
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Quote:
Originally Posted by talon167 View Post

a) RV12 adaptability - if I build an RV12iS now, what is the probability I can take advantage of MOSAIC changes prior to or shortly after completing the build?

b) Will an RV12iS be able to take advantage of the changes via modification?

c) Can the current RV12iS structurally use a Rotax 915iS?

d) With an upgraded engine such as the 135hp 915iS, can the current RV12iS structurally add hundreds of pounds of weight without too much of an issue?
a) - Close to zero.

b) - Probably not, without serious re-engineering and modification.

c) - Probably not.

d) - Nope, not a chance. BIG issues!

Airplanes are an interesting combination of compromises, and their characteristics are highly interrelated. The major ones are structural weight, load, aerodynamic configuration, power, center of gravity and its range, airframe strength and stiffness, and performance. Things like the weight and location of components are also important, but probably not first-order like the others. You really can't change one of those without affecting all the others. It's fascinating to learn about these things, and worth spending some time doing.

Dave

Last edited by David Paule : 09-29-2019 at 02:00 PM.
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  #5  
Old 09-29-2019, 03:17 PM
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rmartingt rmartingt is offline
 
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Some airplanes have a surprising amount of "growth margin" built in; others can often handle such growth with minimal modification. However I suspect the RV-12 (and most other purpose-designed LSAs that meet the regs without winks and nods) can't do this.

The current LSA rules have fixed weight and performance limits; given how many people already see these airplanes as "payload challenged" most designers will likely optimize the airframe to maximize payload while still meeting the necessary structural margins. Doing otherwise adds structural weight for no advantage (see the fixed weight limits).

If this improvement goes through (I'm optimistic about the contents, if not the timeline), then assuming nothing in the current product line fits, I'd expect Van's to come out with something compliant to the new rules. But, I don't work there; I'm just speculating like everyone else.
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  #6  
Old 09-29-2019, 03:50 PM
Mich48041 Mich48041 is offline
 
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If you want a heavier plane, how about an RV-14?
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  #7  
Old 09-30-2019, 05:57 AM
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joe gremlin joe gremlin is offline
 
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Location: Southwest Michigan
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Default

Quote:
Originally Posted by rmartingt View Post

If this improvement goes through (I'm optimistic about the contents, if not the timeline), then assuming nothing in the current product line fits, I'd expect Van's to come out with something compliant to the new rules. But, I don't work there; I'm just speculating like everyone else.
I'd suspect they already have some kind of -12xx in the planning stages. Or at least as much you can have something in the planning stages to meet a reg that doesn't yet exist.

That being said my advice to the OP is life is too short to wait on any entity that moves at the speed of government. Build now. If you want more weight and speed than a -12 build a -9 or a -14.
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  #8  
Old 09-30-2019, 10:56 AM
NinerBikes NinerBikes is offline
 
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Quote:
Originally Posted by Flynfrfun View Post
If you are young enough that a 5yr wait doesn't matter then I say wait and see what happens. If you are up there in age probably better to build now and worry about the changes later. My .02
If you are really up there in age, buy someone else's completed build, and go flying.

Unless you really need something to take up a lot of your spare time, say after you retire, and you want to be a nice guy and stay out of the wife's hair, and in the shop being still productive, buy someone else's baby, but proceed with caution and inspect their craftmanship carefully.
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  #9  
Old 09-30-2019, 01:15 PM
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pjc pjc is offline
 
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Default “Upgrade” paths likely unsatisfactory

Based on your summary and what I have read, the new LSA standards will be significantly different than those in place. This will open up lots of design options relatively far afield (in design space) from the current RV-12is. I expect new clean sheet designs to emerge that will offer better performance than possible via (practical) upgrade from the current RV-12 airframe.

So even if you could do it, you wouldn’t like the result compared to a higher performance new design. I doubt seriously Van’s would even offer a compromised “upgrade” — they too are more likely to simply introduce a new offering — so any modification you might want to perform will lack any sort of factory support. If you really want a one-off RV-12 derivative, you can do that today as an EAB, no need to wait.

My advice, buy or build the plane that offers the performance you want today. I would strongly prefer a proven design (e.g. any of the current Van’s offerings).

Peter
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