Adjustable Prop for a Cessna 150

I notice that there are Ivoprop makes an in flight adjustable
propeller suitable for a an o-200 engine.

I understand that putting this prop on my C-150 is illegal. But
suppose ...

Suppose I put this prop on my Cessna 150. It only weighs 9.5 pounds,
as compared to the Sensenich weight of 24 pounds. So I save 14.5
pounds.

Can anyone guess how this would effect my performance? How much
better climb and how much better cruise?

-Just curious

See http://www.ivoprop.com/inflightultralightmodel.htm
And http://www2.sensenich.com/misc/c150.htm

"Charles Talleyrand" wrote in message
...


Suppose I put this prop on my Cessna 150. It only weighs 9.5 pounds,
as compared to the Sensenich weight of 24 pounds. So I save 14.5 #.

But it will make a largish change in your CG. The fuel and passenger load
for a 150 are both near the CG, so you might end up putting a few pounds of
ballast in the tail to stay within the CG envelope. That would cost you some of
the initial weight advantage.

Can anyone guess how this would effect my performance? How much
better climb and how much better cruise?

Nobody can answer that question until you specify a pitch. Any given fixed
pitch prop will be optimized for climb (at the expense of cruise speed) or
cruise (at the expense of takeoff and climb performance) or somewhere in
between.



--
Vaughn


Nothing personal, but if you are posting through Google Groups I may not receive
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Will poofread for food.

On 08/15/08 12:10, Vaughn Simon wrote:
"Charles Talleyrand" wrote in message
...


Suppose I put this prop on my Cessna 150. It only weighs 9.5 pounds,
as compared to the Sensenich weight of 24 pounds. So I save 14.5 #.

But it will make a largish change in your CG. The fuel and passenger load
for a 150 are both near the CG, so you might end up putting a few pounds of
ballast in the tail to stay within the CG envelope. That would cost you some of
the initial weight advantage.

If you reduce the weight of the prop, won't that move your CG aft?
Requiring less weight in the tail (actually, anywhere behind the CG) to
support the same flight envelope?



Can anyone guess how this would effect my performance? How much
better climb and how much better cruise?

Nobody can answer that question until you specify a pitch. Any given fixed
pitch prop will be optimized for climb (at the expense of cruise speed) or
cruise (at the expense of takeoff and climb performance) or somewhere in
between.






--
Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot
Cal Aggie Flying Farmers
Sacramento, CA

On Aug 15, 3:10 pm, "Vaughn Simon"
wrote:
"Charles Talleyrand" wrote in message

...

Suppose I put this prop on my Cessna 150. It only weighs 9.5 pounds,
as compared to the Sensenich weight of 24 pounds. So I save 14.5 #.

But it will make a largish change in your CG. The fuel and passenger load
for a 150 are both near the CG, so you might end up putting a few pounds of
ballast in the tail to stay within the CG envelope. That would cost you some of
the initial weight advantage.

Can anyone guess how this would effect my performance? How much
better climb and how much better cruise?

Nobody can answer that question until you specify a pitch. Any given fixed
pitch prop will be optimized for climb (at the expense of cruise speed) or
cruise (at the expense of takeoff and climb performance) or somewhere in
between.


Actually, one can assume that it will climb at least as well as the
standard climb prop, and cruise at least as well as the standard
cruise prop.

The difference between the cruise (normal) prop climb performance, and
the climb prop climb performance, will be available to cruise prop
users.

The difference between the climb prop cruise performance, and the
cruise prop cruise performance, will be available to climb prop users.

Anyone know these numbers?

Alternatively, there must be planes that have used both fixed and
constant-speed props. Anyone know the difference?

Charles Talleyrand wrote:
Alternatively, there must be planes that have used both fixed and
constant-speed props. Anyone know the difference?

Don't know about the Cessna 150, but I'm pretty sure some owners of
experimentals (such as the RV series) have tried both fixed and later
constant speed props on the same engine and airframe. If interested, I
suspect one could find numbers mentioned on the forums on this web site:
http://www.vansairforce.net/

On Aug 15, 1:27*pm, Mark Hansen wrote:
On 08/15/08 12:10, Vaughn Simon wrote:

"Charles Talleyrand" wrote in message
....

Suppose I put this prop on my Cessna 150. *It only weighs 9.5 pounds,
as compared to the Sensenich weight of 24 pounds. *So I save 14.5 #.

* * But it will make a largish change in your CG. *The fuel and passenger load
for a 150 are both near the CG, so you might end up putting a few pounds of
ballast in the tail to stay within the CG envelope. *That would cost you some of
the initial weight advantage.

If you reduce the weight of the prop, won't that move your CG aft?
Requiring less weight in the tail (actually, anywhere behind the CG) to
support the same flight envelope?



Can anyone guess how this would effect my performance? *How much
better climb and how much better cruise?

* *Nobody can answer that question until you specify a pitch. *Any given fixed
pitch prop will be optimized for climb (at the expense of cruise speed) or
cruise (at the expense of takeoff and climb performance) or somewhere in
between.

--
Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot
Cal Aggie Flying Farmers
Sacramento, CA

Mark is dead right on this one,,, And you might end up with an ill
handling plane with an aft CG that will happen.....

be safe out there.

"Mark Hansen" wrote in message
...

If you reduce the weight of the prop, won't that move your CG aft?
Requiring less weight in the tail (actually, anywhere behind the CG) to
support the same flight envelope?

(Let's see, how can I gracefully get out of this one...OK, I know...)
Brain fart! Yes, you are 100% correct.

We would need to saw off tail structure to fix the CG. (just kidding)
Worst case, you would need to add weight as far forward as possible, and that
added weight would have to be MORE than the weight that you saved by swapping
the prop because it would necessarily need to be mounted closer to the CG than
where the weight came off (the prop).

Just to add a bit of noise to the discussion, an airplane operating at
maximum allowed aft CG is actually more aerodynamically efficient. Sailplane
pilots often add tail ballast for just this reason.



--
Vaughn


Nothing personal, but if you are posting through Google Groups I may not receive
your message. Google refuses to control the flood of spam messages originating
in their system, so on any given day I may or may not have Google blocked. Try
a real NNTP server & news reader program and you will never go back. All you
need is access to an NNTP server (AKA "news server") and a news reader program.
You probably already have a news reader program in your computer (Hint: Outlook
Express). Assuming that your Usenet needs are modest, use
http://news.aioe.org/ for free and/or http://www.teranews.com/ for a one-time
$3.95 setup fee.


Will poofread for food.

I would think he would need extra weight in the nose.. not in the tail.
BT

"Vaughn Simon" wrote in message
...

"Charles Talleyrand" wrote in message
...


Suppose I put this prop on my Cessna 150. It only weighs 9.5 pounds,
as compared to the Sensenich weight of 24 pounds. So I save 14.5 #.

But it will make a largish change in your CG. The fuel and passenger
load for a 150 are both near the CG, so you might end up putting a few
pounds of ballast in the tail to stay within the CG envelope. That would
cost you some of the initial weight advantage.

Can anyone guess how this would effect my performance? How much
better climb and how much better cruise?

Nobody can answer that question until you specify a pitch. Any given
fixed pitch prop will be optimized for climb (at the expense of cruise
speed) or cruise (at the expense of takeoff and climb performance) or
somewhere in between.



--
Vaughn


Nothing personal, but if you are posting through Google Groups I may not
receive your message. Google refuses to control the flood of spam
messages originating in their system, so on any given day I may or may not
have Google blocked. Try a real NNTP server & news reader program and you
will never go back. All you need is access to an NNTP server (AKA "news
server") and a news reader program. You probably already have a news
reader program in your computer (Hint: Outlook Express). Assuming that
your Usenet needs are modest, use http://news.aioe.org/ for free and/or
http://www.teranews.com/ for a one-time $3.95 setup fee.


Will poofread for food.

Don't forget the CG change.. losing 14# on the nose is a lot.. you are going
to be tail heavy
BT

"Charles Talleyrand" wrote in message
...
On Aug 15, 3:10 pm, "Vaughn Simon"
wrote:
"Charles Talleyrand" wrote in message

...

Suppose I put this prop on my Cessna 150. It only weighs 9.5 pounds,
as compared to the Sensenich weight of 24 pounds. So I save 14.5 #.

But it will make a largish change in your CG. The fuel and passenger
load
for a 150 are both near the CG, so you might end up putting a few pounds
of
ballast in the tail to stay within the CG envelope. That would cost you
some of
the initial weight advantage.

Can anyone guess how this would effect my performance? How much
better climb and how much better cruise?

Nobody can answer that question until you specify a pitch. Any given
fixed
pitch prop will be optimized for climb (at the expense of cruise speed)
or
cruise (at the expense of takeoff and climb performance) or somewhere in
between.


Actually, one can assume that it will climb at least as well as the
standard climb prop, and cruise at least as well as the standard
cruise prop.

The difference between the cruise (normal) prop climb performance, and
the climb prop climb performance, will be available to cruise prop
users.

The difference between the climb prop cruise performance, and the
cruise prop cruise performance, will be available to climb prop users.

Anyone know these numbers?

Alternatively, there must be planes that have used both fixed and
constant-speed props. Anyone know the difference?

Actually I think it was determined in the sailplane circles.. that having
the CG at the 85% point was the most efficient..
too far aft was too much and caused nose down stick putting the elevator
down into the slip stream, and not far enough aft caused back stick or up
elevator into the slip stream.
Heavier pilots do add tail ballast which increases the minimum pilot weight
for club gliders.

BT


Just to add a bit of noise to the discussion, an airplane operating at
maximum allowed aft CG is actually more aerodynamically efficient.
Sailplane pilots often add tail ballast for just this reason.



--
Vaughn