Beta Prop

Wouldn't you have this "effect" ANY time you went from a thrusting to a
braking action with regards to thrust generated?

If I pulled power back, set the pitch to flat, and pushed the nose over,
wouldn't the prop be "driving" the engine in the manner you describe?

All of this is able to be done without a specific Beta range.

Dave

PittsS1C wrote:
Is it a good idea to have beta with any geared engines?

Aren't there typically problems with chattering the gears

back and forth leading to failures?



Mike

"Dave S" wrote in message
nk.net...

I believe you are mistaken on the IVO.

The IVO has a specific range of travel that is accomplished by twisting
the blade midshaft, not rotating the entire blade in the hub.

Also, with the auto engines the original poster is discussing, it is less
a function of the engine and more a function of will the PSRU (re-drive)
support a hydraulic governor. The Marcotte and Mistral PSRU's will support
a hydraulic constant speed prop, others such as the Real World Solutions
brand will not.

An electric MT can be obtained that will run in the beta (and even
reverse) ranges, but that is a $10k US proposition. Of course, getting a
hydraulic governor, the price difference for a redrive that supports one,
and getting a hydraulic CS prop, you are likely there with the cost of an
Electric MT in the first place.

It costs money.. plain and simple.

The IVO may be an option for you, but as for a specific "beta" range, I am
fairly sure it doesnt have one.


Dave

Gig 601XL Builder wrote:

I believe both the Woodcomp and the IVO will go into Beta.


"Rob Fonhof" wrote in message
...


Hi All.
Just wondering if there are any props out there that can be used on an
experimental aircraft engine, ie:subaru or RX-8 Renesis, which have a
beta range. Don't even want to consider a certified unit as this would
probably cost more than the rest of the firewall forward components.
Thanks in advance,
Rob.
Melbourne Australia.

I believe the porper operation of geard engines is not operate in regions of
zero thrust during glides (which is a common occurnace using beta during
taxi...)


Mike

"Dave S" wrote in message
nk.net...
Wouldn't you have this "effect" ANY time you went from a thrusting to a
braking action with regards to thrust generated?

If I pulled power back, set the pitch to flat, and pushed the nose over,
wouldn't the prop be "driving" the engine in the manner you describe?

All of this is able to be done without a specific Beta range.

Dave

PittsS1C wrote:
Is it a good idea to have beta with any geared engines?

Aren't there typically problems with chattering the gears

back and forth leading to failures?



Mike

"Dave S" wrote in message
nk.net...

I believe you are mistaken on the IVO.

The IVO has a specific range of travel that is accomplished by twisting
the blade midshaft, not rotating the entire blade in the hub.

Also, with the auto engines the original poster is discussing, it is less
a function of the engine and more a function of will the PSRU (re-drive)
support a hydraulic governor. The Marcotte and Mistral PSRU's will
support a hydraulic constant speed prop, others such as the Real World
Solutions brand will not.

An electric MT can be obtained that will run in the beta (and even
reverse) ranges, but that is a $10k US proposition. Of course, getting a
hydraulic governor, the price difference for a redrive that supports one,
and getting a hydraulic CS prop, you are likely there with the cost of an
Electric MT in the first place.

It costs money.. plain and simple.

The IVO may be an option for you, but as for a specific "beta" range, I
am fairly sure it doesnt have one.


Dave

Gig 601XL Builder wrote:

I believe both the Woodcomp and the IVO will go into Beta.


"Rob Fonhof" wrote in message
...


Hi All.
Just wondering if there are any props out there that can be used on an
experimental aircraft engine, ie:subaru or RX-8 Renesis, which have a
beta range. Don't even want to consider a certified unit as this would
probably cost more than the rest of the firewall forward components.
Thanks in advance,
Rob.
Melbourne Australia.

I have forwarded this thread to the manufacturer of my redrive and to
the rotary engine discussion group to see if this concern has been borne
out in that engine type (that is one of the powerplants the OP was
inquiring about, as well as the powerplant that I am building now).

I am not contesting what you are claiming with regards to GO- series
engines, and operation at zero or less than zero net thrust in those
powerplants.

Dave

PittsS1C wrote:

I believe the porper operation of geard engines is not operate in regions of
zero thrust during glides (which is a common occurnace using beta during
taxi...)


Mike

"Dave S" wrote in message
nk.net...

Wouldn't you have this "effect" ANY time you went from a thrusting to a
braking action with regards to thrust generated?

If I pulled power back, set the pitch to flat, and pushed the nose over,
wouldn't the prop be "driving" the engine in the manner you describe?

All of this is able to be done without a specific Beta range.

Dave

PittsS1C wrote:

Is it a good idea to have beta with any geared engines?

Aren't there typically problems with chattering the gears

back and forth leading to failures?



Mike

"Dave S" wrote in message
hlink.net...


I believe you are mistaken on the IVO.

The IVO has a specific range of travel that is accomplished by twisting
the blade midshaft, not rotating the entire blade in the hub.

Also, with the auto engines the original poster is discussing, it is less
a function of the engine and more a function of will the PSRU (re-drive)
support a hydraulic governor. The Marcotte and Mistral PSRU's will
support a hydraulic constant speed prop, others such as the Real World
Solutions brand will not.

An electric MT can be obtained that will run in the beta (and even
reverse) ranges, but that is a $10k US proposition. Of course, getting a
hydraulic governor, the price difference for a redrive that supports one,
and getting a hydraulic CS prop, you are likely there with the cost of an
Electric MT in the first place.

It costs money.. plain and simple.

The IVO may be an option for you, but as for a specific "beta" range, I
am fairly sure it doesnt have one.


Dave

Gig 601XL Builder wrote:


I believe both the Woodcomp and the IVO will go into Beta.


"Rob Fonhof" wrote in message
...



Hi All.
Just wondering if there are any props out there that can be used on an
experimental aircraft engine, ie:subaru or RX-8 Renesis, which have a
beta range. Don't even want to consider a certified unit as this would
probably cost more than the rest of the firewall forward components.
Thanks in advance,
Rob.
Melbourne Australia.

"Dave S" wrote in message
nk.net...
Wouldn't you have this "effect" ANY time you went from a thrusting to a
braking action with regards to thrust generated?

If I pulled power back, set the pitch to flat, and pushed the nose over,
wouldn't the prop be "driving" the engine in the manner you describe?

All of this is able to be done without a specific Beta range.

Dave

Actually, no. Kinda. g

When the engine is using HP to turn the prop, all is well, be it forward or
reverse thrust. The only difference the gearing sees is the thrust on the
shaft goes from pulling the shaft out, to pushing the shaft in, but the load
on the gears is the same. (all for tractor applications, in this case)

When the possible chattering comes in, is when you are gliding, and at a
very low power setting, and the *windmilling* prop is trying to turn the
engine, thus the prop is "making" HP to try to turn the engine- opposite
from normal.
--
Jim in NC

And after discussing it with the rotary engine gang, the consensus is..
that you pass through this area of "chatter" fairly quickly.. either you
are engine driving prop.. or prop driving engine... but from a practical
matter you are not loitering in the power/thrust range that is teetering
between the two.

Every geared engine passes through this range several times on a given
flight, but rarely loiters there.

Even in ground ops.. you are pushing.. or pulling.. but rarely
straddling the fence.

Dave

Morgans wrote:
"Dave S" wrote in message
nk.net...

Wouldn't you have this "effect" ANY time you went from a thrusting to a
braking action with regards to thrust generated?

If I pulled power back, set the pitch to flat, and pushed the nose over,
wouldn't the prop be "driving" the engine in the manner you describe?

All of this is able to be done without a specific Beta range.

Dave


Actually, no. Kinda. g

When the engine is using HP to turn the prop, all is well, be it forward or
reverse thrust. The only difference the gearing sees is the thrust on the
shaft goes from pulling the shaft out, to pushing the shaft in, but the load
on the gears is the same. (all for tractor applications, in this case)

When the possible chattering comes in, is when you are gliding, and at a
very low power setting, and the *windmilling* prop is trying to turn the
engine, thus the prop is "making" HP to try to turn the engine- opposite
from normal.

I guess my point was that, whenever I have been with someone using beta,
they spent lots of time loitering there.
Positive thrust to get moving then hanging out in the zero thrust area with
little adjustments positive and negative during taxi.
I think I would hesitate to use a geared engine for taxing that way (like
turbine planes do)


"Dave S" wrote in message
nk.net...
And after discussing it with the rotary engine gang, the consensus is..
that you pass through this area of "chatter" fairly quickly.. either you
are engine driving prop.. or prop driving engine... but from a practical
matter you are not loitering in the power/thrust range that is teetering
between the two.

Every geared engine passes through this range several times on a given
flight, but rarely loiters there.

Even in ground ops.. you are pushing.. or pulling.. but rarely straddling
the fence.

Dave

Morgans wrote:
"Dave S" wrote in message
nk.net...

Wouldn't you have this "effect" ANY time you went from a thrusting to a
braking action with regards to thrust generated?

If I pulled power back, set the pitch to flat, and pushed the nose over,
wouldn't the prop be "driving" the engine in the manner you describe?

All of this is able to be done without a specific Beta range.

Dave


Actually, no. Kinda. g

When the engine is using HP to turn the prop, all is well, be it forward
or
reverse thrust. The only difference the gearing sees is the thrust on
the
shaft goes from pulling the shaft out, to pushing the shaft in, but the
load
on the gears is the same. (all for tractor applications, in this case)

When the possible chattering comes in, is when you are gliding, and at a
very low power setting, and the *windmilling* prop is trying to turn the
engine, thus the prop is "making" HP to try to turn the engine- opposite
from normal.

On Wed, 10 Aug 2005 00:57:18 -0400, Morgans wrote:


"Jim Carriere" wrote

It's handy (beta) during taxiing when you can get no or slight reverse
thrust, that saves your brakes and is less workload when you get the
hang of it. It's usually a bad idea to reverse taxi- kick up fod then
roll through it as the engine ingests it, hard to see where you're
going, the nose (or tail) wheel may not castor 360 degrees... to name a
few reasons.

It is also -really- handy for seaplanes, who have *no* brakes. ;-))


But, having a prop with a beta or reverse capability adds new very nasty
failure modes. Type certificated aircraft with props that have a beta or
reverse functionality have additional complicated monitors to prevent the
prop from going into uncommanded beta or reverse in flight. I would want
a prop with the low pitch stop set to a position that is safe for
in-flight operation. If the prop goes into beta or reverse in the air it
can kill you.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com

"Dave S" wrote

And after discussing it with the rotary engine gang, the consensus is..
that you pass through this area of "chatter" fairly quickly.. either you
are engine driving prop.. or prop driving engine... but from a practical
matter you are not loitering in the power/thrust range that is teetering
between the two.

All very true. You get pressure of the opposite side of the gears from
normal, but it would indeed be rare for it to get to the RPM where it is so
closely balanced, as to go from one to the other, rapidly.

All of this is reason to make the gears tight fitting, with little lash.
More lash gives time for the motion to set up with a "head start", providing
more force to break things. Broken things = bad. g
--
Jim in NC
--
Jim in NC

"PittsS1C" wrote

Positive thrust to get moving then hanging out in the zero thrust area
with
little adjustments positive and negative during taxi.
I think I would hesitate to use a geared engine for taxing that way (like
turbine planes do)

I can't say with 100% authority, but I don't see that as a problem. Just
because there is zero thrust, does not mean the engine/gearbox has zero
load. Even at beta, the prop is still moving a lot of air, but off of the
front and the back and ends of the prop, at the same time. Considerable HP
is still being used, and putting a constant, normal load on the gears.

Think of a "club" prop, for breaking in engines, or using on a "torque" type
dyno. It is indeed putting a load on the engine and gearbox, but it is not
trying to make thrust, so the test stand/dyno doesn't zoom down the length
of the driveway. g
--
Jim in NC