changing operating limitations

On Mon, 15 Aug 2005 20:21:57 -0400, "Morgans"
wrote:

"pittss1c" wrote

to have a max continous RPM of...say 2000. (as part of "your"
design to get a higher TBO)

It will not be allowed. The rule plainly states that it is not to exceed
120 knots at wide open throttle.

I'd certainly like for a citation on that one. While neither a pilot
or a builder, I follow the Sonex site; their plane with the Jab 3300,
at WOT, greatly exceeds limits. As they understand it, the rule is
"Maximum speed in level flight with maximum continuous power (Vh) of
not more than 120 kts (138 mph) CAS under standard atmospheric
conditions at sea level." The word "continuous" is in there ... the
3300 Jabiru is specified at 2750 RPM max continuous which keeps things
legal. Many of the owners report significantly higher capability ...
and maximum RPM is specified, IIRC, at 3300.

In a word NO! The key word is continuously operated with operating limits
at or less than the prescribed limits for LSA. Must be correctly done at the
end of the test period.

--
Cy Galley
EAA Safety Programs Editor
Always looking for ideas and articles for EAA Sport Pilot


"pittss1c" wrote in message
...
Is it possible to change the operating limitations of your homebuilt after
it has been certified?
Let me take the more extreme case...
I was wondering, if one owned (or bought) an RV3, is it possible to change
the operating limitiations to have a red line of 120 knots, and a maximum
continous RPM that arrives at a speed or 120 knots?
This would potentially make it fit as a sport pilot airplane (when flown
within the operating limitations)


Mike

"pittss1c" wrote in message
...
Is it possible to change the operating limitations of your homebuilt after
it has been certified?
Let me take the more extreme case...
I was wondering, if one owned (or bought) an RV3, is it possible to change
the operating limitiations to have a red line of 120 knots, and a maximum
continous RPM that arrives at a speed or 120 knots?
This would potentially make it fit as a sport pilot airplane (when flown
within the operating limitations)

Mike..........

Unless I'm greatly mistaken, neither RPM nor airspeed limits are contained
in the Operating Limitations of an Experimental, Amateur-built aircraft.

Rich S.

X-No-Archive

"Morgans" wrote in message
...

If you took a Lycoming, and said you were going to limit it for continuous
operation at 2,000 RPM, that would not fly for the sport plane
restrictions.
They (the FAA) all know that this engine can run much faster than that,
with
no harm. So you are told to try again; no dice.

Jim...........

There are many factors besides engine operating parameters which limit
cruising speed. In some aircraft it may be control surface flutter, others
may be subject to overstress by outside aerodynamic forces (hence
maneuvering speed). While an engine may be capable of driving an airframe at
speeds in excess of 120 knots, the airframe itself may be beyond it's
limits.

The fellow who is holding the stick has the legal responsibility for setting
the limits of safe operation on every flight. Just because a designer says
it can do more, doesn't mean it will. That's what test periods are for.

Let's not become our own worst enemy here by espousing a rule that few
people think makes any sense at all -outside the group of new LSA
manufacturers who stand to make a buck selling their airplanes. I'm not
talking about the speed limit, BTW. I'm talking about the "You crossed the
line and can't go back" clause.

Rich S.

"GeorgeB" wrote

I'd certainly like for a citation on that one. While neither a pilot
or a builder, I follow the Sonex site; their plane with the Jab 3300,
at WOT, greatly exceeds limits.

You are right on that, I believe. At one time it was stated as WOT.

As they understand it, the rule is
"Maximum speed in level flight with maximum continuous power (Vh) of
not more than 120 kts (138 mph) CAS under standard atmospheric
conditions at sea level." The word "continuous" is in there ... the
3300 Jabiru is specified at 2750 RPM max continuous which keeps things
legal. Many of the owners report significantly higher capability ...
and maximum RPM is specified, IIRC, at 3300.

I think you have the key here, when you say the Jab engine is rated for 2700
continuous. (by the manufacturer) That is in line with other direct drive
RPMs. The higher RPM's can be done with that engine, but just like the
other major direct drive makers, you can not run them for long at those
speeds, without some consequences.

If you took a Lycoming, and said you were going to limit it for continuous
operation at 2,000 RPM, that would not fly for the sport plane restrictions.
They (the FAA) all know that this engine can run much faster than that, with
no harm. So you are told to try again; no dice.

It seems if you have a homebrew engine, you have an advantage, because you
are the one that will set the continuous operating RPM's. That is my take,
anyway.

Sorry about the WOT bit. Best be having the WOT close to the continuous
RPM, if you want to have a chance of passing, IMHO.

A lot of these things are unknown, since the envelope has not yet been
pushed, and case precedents have not been established, yet. We will have to
wait and see how much they will let us get away with. g
--
Jim in NC

pittss1c wrote:
Is it possible to change the operating limitations of your homebuilt
after it has been certified?
Let me take the more extreme case...
I was wondering, if one owned (or bought) an RV3, is it possible to
change the operating limitiations to have a red line of 120 knots, and a
maximum continous RPM that arrives at a speed or 120 knots?
This would potentially make it fit as a sport pilot airplane (when flown
within the operating limitations)


Mike

Or just wait till Van comes out with a new LSA compliant RV:-)

Jerry

I think that all you have to do to make your "Lycoming" into a "pittss1c
Super Advanced Powerplant" is to remove the dataplate from the engine
and attach one made by you. It is now uncertified and you would be free
to do what you want with it.

pittss1c wrote:


"pittss1c" wrote
snip

I was just thinking, the designer sets the operating limitations of a
homebuilt's engine.
therefore one could define an engine based on lycoming parts (up to 100%
lycoming) to have a max continous RPM of...say 2000. (as part of "your"
design to get a higher TBO)

If I was to build up an engine with parts out of my garage, I would set
the operating limitations, and would set the Vne of my own design/airplane.

Mike

Jim,
I have spoken to a few Sonex builders /owners and they pretty much all
agree the best way to stay in the sport pilot class with a Sonex is to use a
VW powerplant and a climb prop, a cruise prop on the VW still puts you over
the cruise speed. It's a sharp little plane!

Patrick
student SPL
aircraft structural mech

"Morgans" wrote in message
...

"GeorgeB" wrote

I'd certainly like for a citation on that one. While neither a pilot
or a builder, I follow the Sonex site; their plane with the Jab 3300,
at WOT, greatly exceeds limits.

You are right on that, I believe. At one time it was stated as WOT.

As they understand it, the rule is
"Maximum speed in level flight with maximum continuous power (Vh) of
not more than 120 kts (138 mph) CAS under standard atmospheric
conditions at sea level." The word "continuous" is in there ... the
3300 Jabiru is specified at 2750 RPM max continuous which keeps things
legal. Many of the owners report significantly higher capability ...
and maximum RPM is specified, IIRC, at 3300.

I think you have the key here, when you say the Jab engine is rated for
2700
continuous. (by the manufacturer) That is in line with other direct drive
RPMs. The higher RPM's can be done with that engine, but just like the
other major direct drive makers, you can not run them for long at those
speeds, without some consequences.

If you took a Lycoming, and said you were going to limit it for continuous
operation at 2,000 RPM, that would not fly for the sport plane
restrictions.
They (the FAA) all know that this engine can run much faster than that,
with
no harm. So you are told to try again; no dice.

It seems if you have a homebrew engine, you have an advantage, because you
are the one that will set the continuous operating RPM's. That is my
take,
anyway.

Sorry about the WOT bit. Best be having the WOT close to the continuous
RPM, if you want to have a chance of passing, IMHO.

A lot of these things are unknown, since the envelope has not yet been
pushed, and case precedents have not been established, yet. We will have
to
wait and see how much they will let us get away with. g
--
Jim in NC

Scott wrote:
I think that all you have to do to make your "Lycoming" into a "pittss1c
Super Advanced Powerplant" is to remove the dataplate from the engine
and attach one made by you. It is now uncertified and you would be free
to do what you want with it.

That was my take on it... If they ask too many questions tell them you
have modified chevy rods in it

Rich S. wrote:
"pittss1c" wrote in message
...

Is it possible to change the operating limitations of your homebuilt after
it has been certified?
Let me take the more extreme case...
I was wondering, if one owned (or bought) an RV3, is it possible to change
the operating limitiations to have a red line of 120 knots, and a maximum
continous RPM that arrives at a speed or 120 knots?
This would potentially make it fit as a sport pilot airplane (when flown
within the operating limitations)


Mike..........

Unless I'm greatly mistaken, neither RPM nor airspeed limits are contained
in the Operating Limitations of an Experimental, Amateur-built aircraft.

Rich S.


Not sure if it is true, but my understanding was that the instrument
markings were required as the operating limitations.