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1. 07:46 AM - Re: Engine down thrust angle (FLYaDIVE)
2. 08:58 AM - Re: Engine down thrust angle (flyv35b)
3. 10:25 AM - Re: Engine down thrust angle (Gary Vogt)
4. 10:45 AM - Re: Engine down thrust angle (David Boone)
5. 09:16 PM - Re: Engine down thrust angle (Gary Vogt)
Message 1
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| Subject: | Re: Engine down thrust angle |
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as
I.
And Gary... Thank you for the due respect, but it is perfectly alright for
you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
> Hi Barry,
>
> with all due respect, what you say does make some sense, but . . .
>
> There is a down thrust on the elevator to keep the nose up and that is
> created by the air flow. (HUH?)
> - - - - In flight, the elevator is rarely in a position to raise the
> nose on a plane that wants to go fast. Disregarding the drawing in "Stick
> and Rudder," if you want to go fast, the horizontal needs to be flying.
> I.e., the elevator needs to be lifting the plane. Or, at a bare minimum,
> provide a minimum down force. That is why the plane is faster with aft CG
> loading.
>
[Barry] - On many planes - I do not have Grumman's build procedure or
the maintainance manual in front of me ... But you will find
the horizontal stabilizer to be in a NEGATIVE angle. This creates a down
thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the
center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the
plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight
area) is pointing slightly down. Elevator trailing edge up. This varies on
our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B
with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how
does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail
down so there is a balance to the See-Saw. Counter balancing the weight of
the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI)
of the main wing. Well in this balance situation, this angle (AoI) is there
to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We
are keeping things simple so we do not have to deal with adding and
subtracting vectors. We can simply say the AoI is over coming the weight of
the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the
Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
> - - - - With a down thrust angle, less force is needed on the tail to
> hold the tail down.
>
[Barry] - TRUE.... That is what I said. We are saying the same thing.
>
> There is a lateral pivot point which balances down thrust of the
> elevator against down thrust of the engine.
> - - - - Down thrust of the engine? What are you talking about here?
> The elevator down thrust, from the classical point of view, balances the
> lift from the wing about the aircraft CG.
>
[Barry] - I don't think you mean to question is there such a thing as engine
down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the
wing... What about the weight of the engine. You have a See-Saw that
balances on the CG. But there is also the weight of the engine and thrust
angle of the engine. There is more than just lift of the wings.
> AND this is a BIG ONE - It is much easier to land a plane with down-thrust
> to an engine than one with up-thrust. With up-thrust you have to fly the
> plane onto the runway. SO, what happens with ZERO Thrust?
> - - - - I flew the subjects plane before lowering the engine 1/2
> degree. I flew it after. I didn't notice any difference. It still has .3
> degrees up thrust angle. The plane flies fine.
>
> - - - - In a landing configuration, there is so little thrust from the
> engine compared to the aircraft angle of attack as to make it a non-issue.
>
> - - - - I do agree that with and engine with several degrees of up angle
> thrust, it would be like landing down-wind.
>
[Barry] - We AGREE here also. Obvously the small changes you are working
with are not enough to be noticed or :-) Upset the apple cart :-)
>
> There is more of a neutral feel and WHICH I PREFER - And when power is cut
> there is only a small pitch change.
> - - - - Modelers that build free flight and remote control always build
> with down thrust on the engine. There is a web site for remote control
> plane builders that outlines the process for determining the optimum down
> thrust to keep the plane stable during throttle changes.
>
> - - - - With an increase in power from cruise condition, the increase
> in effective angle-of-attack due to increase speed, has the effect of
> lifting the nose of the plane about the CG. With a down thrust angle, the
> plane feels more stable.
>
> - - - - Likewise, with a decrease in power from a full power condition,
> the plane will want to drop it's nose. With a down thrust angle, that trim
> has already been trimmed in and the effect is less diversion from horizontal
> flight; i.e., a more stable airplane.
>
> [Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way
back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to
Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the
main wing as well as the Horz Stab. (Of course some do have
a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40
CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall
the advertised HP, I'm just using a S.W.A.G. and more than likely it was
higher... Especially my re-worked engines :-)
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP
per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot
> of down elevator is used to keep the plane S&L. So what happens with
> Down-Thrust?
> - - - - see above. I agree.
>
> When the power is cut the plane will start to balloon just a little... Most
> people will not even notice it. And in many cases you will already be
> trimmed very close to best glide SO there is less work to do when setting up
> for a landing.
> - - - - see above. I agree.
>
> NOW! ALL this information is dependent on HOW MUCH thrust we are talking
> about.
> If the feel is that noticeable you have some major thrust errors to
> correct.
>
>
[Barry] - So Gary --- I believe we agree... Just a different ways of
explaining it.
Barry
>
>
> ------------------------------
> *From:* FLYaDIVE <flyadive@gmail.com>
>
> *To:* teamgrumman-list@matronics.com
> *Sent:* Thu, February 10, 2011 5:06:11 PM
>
> *Subject:* Re: TeamGrumman-List: Engine down thrust angle
>
> Gary & Team:
>
> From my experienced down thrust is a good thing ... IN MODERATION.
>
> There is a down thrust on the elevator to keep the nose up and that is
> created by the air flow.
> There is a lateral pivot point which balances down thrust of the
> elevator against down thrust of the engine.
> AND this is a BIG ONE - It is much easier to land a plane with down-thrust
> to an engine than one with up-thrust. With up-thrust you have to fly the
> plane onto the runway. SO, what happens with ZERO Thrust?
> There is more of a neutral feel and WHICH I PREFER - And when power is cut
> there is only a small pitch change.
> With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot
> of down elevator is used to keep the plane S&L. So what happens with
> Down-Thrust?
> When the power is cut the plane will start to balloon just a little... Most
> people will not even notice it. And in many cases you will already be
> trimmed very close to best glide SO there is less work to do when setting up
> for a landing.
> NOW! ALL this information is dependent on HOW MUCH thrust we are talking
> about.
> If the feel is that noticeable you have some major thrust errors to
> correct.
> Barry
> "Chop'd Liver"
>
> *
>
> *
>
>
> *
>
>
> *
>
>
Message 2
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| Subject: | Re: Engine down thrust angle |
"AND as you said - "the elevator needs to be lifting the plane" ... But
how does it lift the plane? Not by LIFTING the TAIL... But by pushing
the tail down so there is a balance to the See-Saw. Counter balancing
the weight of the engine and in some... Down Thrust."
Another way of looking at this is the wing has a center of pressure, Cp,
where the lift vector is located. This changes with AOA and is located
aft of the CG in all the planes we typically fly. This Cp creates a
pitching moment which is nose down and needs to be counteracted by a
down force from the tail to keep the plane in balance. That's why as
the CG moves aft the pitching moment decreases and there is less down
force required by the tail and therefore less tail drag. To this
equation you have a thrust and a drag vector and to the extent that they
don't coincide you have a change in this moment about the CG which could
add or subtract from the pitching moment (low wing vs high wing, engine
thrust angle).
I have heard of a 2 place Grumman that had the horizontal stabilizer
angle of incidence "changed" to reduce the tail drag and apparently had
a sizeable increase in speed, probably at the expense of stability.
Cliff
----- Original Message -----
From: FLYaDIVE
To: teamgrumman-list@matronics.com
Sent: Saturday, February 12, 2011 7:31 AM
Subject: Re: TeamGrumman-List: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same
thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright
for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman@yahoo.com>
wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that
is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise
the nose on a plane that wants to go fast. Disregarding the drawing in
"Stick and Rudder," if you want to go fast, the horizontal needs to be
flying. I.e., the elevator needs to be lifting the plane. Or, at a
bare minimum, provide a minimum down force. That is why the plane is
faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or
the maintainance manual in front of me ... But you will find the
horizontal stabilizer to be in a NEGATIVE angle. This creates a down
thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the
center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane
trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance
weight area) is pointing slightly down. Elevator trailing edge up.
This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this.
On the AA5-A & B with the bigger Horz Stab does not show this as much or
at all.
AND as you said - "the elevator needs to be lifting the plane" ... But
how does it lift the plane? Not by LIFTING the TAIL... But by pushing
the tail down so there is a balance to the See-Saw. Counter balancing
the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants
(AoI) of the main wing. Well in this balance situation, this angle
(AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into
play. We are keeping things simple so we do not have to deal with
adding and subtracting vectors. We can simply say the AoI is over
coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on
the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
- - - - With a down thrust angle, less force is needed on the
tail to hold the tail down.
[Barry] - TRUE.... That is what I said. We are saying the same thing.
There is a lateral pivot point which balances down thrust of the
elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about
here? The elevator down thrust, from the classical point of view,
balances the lift from the wing about the aircraft CG.
[Barry] - I don't think you mean to question is there such a thing as
engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the
wing... What about the weight of the engine. You have a See-Saw that
balances on the CG. But there is also the weight of the engine and
thrust angle of the engine. There is more than just lift of the wings.
AND this is a BIG ONE - It is much easier to land a plane with
down-thrust to an engine than one with up-thrust. With up-thrust you
have to fly the plane onto the runway. SO, what happens with ZERO
Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2
degree. I flew it after. I didn't notice any difference. It still has
.3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from
the engine compared to the aircraft angle of attack as to make it a
non-issue.
- - - - I do agree that with and engine with several degrees of
up angle thrust, it would be like landing down-wind.
[Barry] - We AGREE here also. Obvously the small changes you are
working with are not enough to be noticed or :-) Upset the apple cart
:-)
There is more of a neutral feel and WHICH I PREFER - And when power
is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control
always build with down thrust on the engine. There is a web site for
remote control plane builders that outlines the process for determining
the optimum down thrust to keep the plane stable during throttle
changes.
- - - - With an increase in power from cruise condition, the
increase in effective angle-of-attack due to increase speed, has the
effect of lifting the nose of the plane about the CG. With a down
thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power
condition, the plane will want to drop it's nose. With a down thrust
angle, that trim has already been trimmed in and the effect is less
diversion from horizontal flight; i.e., a more stable airplane.
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee
way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ...
HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence
(AoI) to the main wing as well as the Horz Stab. (Of course some do
have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had
a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall
the advertised HP, I'm just using a S.W.A.G. and more than likely it was
higher... Especially my re-worked engines :-)
Nope - I did not have a NELSON 40... there you are talking close to 2
HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only:
0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
With Up-Thrust when the power in cut the plane wants to DIVE - Since
a lot of down elevator is used to keep the plane S&L. So what happens
with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a
little... Most people will not even notice it. And in many cases you
will already be trimmed very close to best glide SO there is less work
to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are
talking about.
If the feel is that noticeable you have some major thrust errors to
correct.
[Barry] - So Gary --- I believe we agree... Just a different ways of
explaining it.
Barry
-------------------------------------------------------------------------
---
From: FLYaDIVE <flyadive@gmail.com>
To: teamgrumman-list@matronics.com
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: TeamGrumman-List: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that
is created by the air flow.
There is a lateral pivot point which balances down thrust of the
elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with
down-thrust to an engine than one with up-thrust. With up-thrust you
have to fly the plane onto the runway. SO, what happens with ZERO
Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power
is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since
a lot of down elevator is used to keep the plane S&L. So what happens
with Down-Thrust?
When the power is cut the plane will start to balloon just a
little... Most people will not even notice it. And in many cases you
will already be trimmed very close to best glide SO there is less work
to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are
talking about.
If the feel is that noticeable you have some major thrust errors to
correct.
Barry
"Chop'd Liver"
st"
target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
Message 3
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| Subject: | Re: Engine down thrust angle |
whatever
________________________________
From: FLYaDIVE <flyadive@gmail.com>
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: TeamGrumman-List: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you
to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
Hi Barry,
>
>
>with all due respect, what you say does make some sense, but . . .
>
>
>There is a down thrust on the elevator to keep the nose up and that is created
>by the air flow. (HUH?)
> - - - - In flight, the elevator is rarely in a position to raise the nose
on
>a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder,"
> if you want to go fast, the horizontal needs to be flying. I.e., the elevator
>needs to be lifting the plane. Or, at a bare minimum, provide a minimum down
>force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or
the maintainance manual in front of me ... But you will find
the horizontal stabilizer to be in a NEGATIVE angle. This creates a down
thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center
and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out
for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area)
is pointing slightly down. Elevator trailing edge up. This varies on our
planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the
bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does
it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so
there is a balance to the See-Saw. Counter balancing the weight of the engine
and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of
the main wing. Well in this balance situation, this angle (AoI) is there to
lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are
keeping things simple so we do not have to deal with adding and subtracting
vectors. We can simply say the AoI is over coming the weight of the plane and
lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz
Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
>
> - - - - With a down thrust angle, less force is needed on the tail to hold
>the tail down.
[Barry] - TRUE.... That is what I said. We are saying the same thing.
>There is a lateral pivot point which balances down thrust of the
>elevator against down thrust of the engine.
> - - - - Down thrust of the engine? What are you talking about here? The
>elevator down thrust, from the classical point of view, balances the lift from
>the wing about the aircraft CG.
[Barry] - I don't think you mean to question is there such a thing as engine
down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing...
What about the weight of the engine. You have a See-Saw that balances on the
CG. But there is also the weight of the engine and thrust angle of the engine.
There is more than just lift of the wings.
>AND this is a BIG ONE - It is much easier to land a plane with down-thrust to
an
>engine than one with up-thrust. With up-thrust you have to fly the plane onto
>the runway. SO, what happens with ZERO Thrust?
> - - - - I flew the subjects plane before lowering the engine 1/2 degree.
I
>flew it after. I didn't notice any difference. It still has .3 degrees up
>thrust angle. The plane flies fine.
>
>
> - - - - In a landing configuration, there is so little thrust from the engine
>compared to the aircraft angle of attack as to make it a non-issue.
>
>
> - - - - I do agree that with and engine with several degrees of up angle
>thrust, it would be like landing down-wind.
[Barry] - We AGREE here also. Obvously the small changes you are working with
are not enough to be noticed or :-) Upset the apple cart :-)
>There is more of a neutral feel and WHICH I PREFER - And when power is cut there
>is only a small pitch change.
> - - - - Modelers that build free flight and remote control always build with
>down thrust on the engine. There is a web site for remote control plane
>builders that outlines the process for determining the optimum down thrust to
>keep the plane stable during throttle changes.
>
>
> - - - - With an increase in power from cruise condition, the increase in
>effective angle-of-attack due to increase speed, has the effect of lifting the
>nose of the plane about the CG. With a down thrust angle, the plane feels more
>stable.
>
>
> - - - - Likewise, with a decrease in power from a full power condition, the
>plane will want to drop it's nose. With a down thrust angle, that trim has
>already been trimmed in and the effect is less diversion from horizontal flight;
>i.e., a more stable airplane.
>
>
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back
in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to
Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main
wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn
engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP,
I'm just using a S.W.A.G. and more than likely it was higher... Especially my
re-worked engines :-)
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per
Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of
down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
> - - - - see above. I agree.
>
>
>When the power is cut the plane will start to balloon just a little... Most
>people will not even notice it. And in many cases you will already be trimmed
>very close to best glide SO there is less work to do when setting up for a
>landing.
> - - - - see above. I agree.
>
>NOW! ALL this information is dependent on HOW MUCH thrust we are talking
about.
>If the feel is that noticeable you have some major thrust errors to correct.
>
>
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining
it.
Barry
>
>
________________________________
From: FLYaDIVE <flyadive@gmail.com>
>
>To: teamgrumman-list@matronics.com
>Sent: Thu, February 10, 2011 5:06:11 PM
>
>Subject: Re: TeamGrumman-List: Engine down thrust angle
>
>
>Gary & Team:
>
>
>From my experienced down thrust is a good thing ... IN MODERATION.
>
>There is a down thrust on the elevator to keep the nose up and that is created
>by the air flow.
>There is a lateral pivot point which balances down thrust of the
>elevator against down thrust of the engine.
>AND this is a BIG ONE - It is much easier to land a plane with down-thrust to
an
>engine than one with up-thrust. With up-thrust you have to fly the plane onto
>the runway. SO, what happens with ZERO Thrust?
>There is more of a neutral feel and WHICH I PREFER - And when power is cut there
>is only a small pitch change.
>With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of
>down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
>When the power is cut the plane will start to balloon just a little... Most
>people will not even notice it. And in many cases you will already be trimmed
>very close to best glide SO there is less work to do when setting up for a
>landing.
>NOW! ALL this information is dependent on HOW MUCH thrust we are talking
about.
>If the feel is that noticeable you have some major thrust errors to correct.
>
>Barry
>"Chop'd Liver"
>
> st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List
> tp://forums.matronics.com _blank">http://www.matronics.com/contribution
Message 4
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| Subject: | Engine down thrust angle |
Gary, do you have a website. Thanks David
From: owner-teamgrumman-list-server@matronics.com
[mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
Subject: Re: TeamGrumman-List: Engine down thrust angle
whatever
_____
From: FLYaDIVE <flyadive@gmail.com>
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: TeamGrumman-List: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as
I.
And Gary... Thank you for the due respect, but it is perfectly alright for
you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is
created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the
nose on a plane that wants to go fast. Disregarding the drawing in "Stick
and Rudder," if you want to go fast, the horizontal needs to be flying.
I.e., the elevator needs to be lifting the plane. Or, at a bare minimum,
provide a minimum down force. That is why the plane is faster with aft CG
loading.
[Barry] - On many planes - I do not have Grumman's build procedure or the
maintainance manual in front of me ... But you will find the horizontal
stabilizer to be in a NEGATIVE angle. This creates a down thrust on the
tail.
NOW! GC is all important but just for S&G's lets say the CG is in the
center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed
out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight
area) is pointing slightly down. Elevator trailing edge up. This varies on
our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B
with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how
does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail
down so there is a balance to the See-Saw. Counter balancing the weight of
the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI)
of the main wing. Well in this balance situation, this angle (AoI) is there
to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We
are keeping things simple so we do not have to deal with adding and
subtracting vectors. We can simply say the AoI is over coming the weight of
the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the
Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
- - - - With a down thrust angle, less force is needed on the tail to
hold the tail down.
[Barry] - TRUE.... That is what I said. We are saying the same thing.
There is a lateral pivot point which balances down thrust of the elevator
against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here?
The elevator down thrust, from the classical point of view, balances the
lift from the wing about the aircraft CG.
[Barry] - I don't think you mean to question is there such a thing as engine
down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the
wing... What about the weight of the engine. You have a See-Saw that
balances on the CG. But there is also the weight of the engine and thrust
angle of the engine. There is more than just lift of the wings.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust
to an engine than one with up-thrust. With up-thrust you have to fly the
plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree.
I flew it after. I didn't notice any difference. It still has .3 degrees
up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the
engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle
thrust, it would be like landing down-wind.
[Barry] - We AGREE here also. Obvously the small changes you are working
with are not enough to be noticed or :-) Upset the apple cart :-)
There is more of a neutral feel and WHICH I PREFER - And when power is cut
there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build
with down thrust on the engine. There is a web site for remote control
plane builders that outlines the process for determining the optimum down
thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in
effective angle-of-attack due to increase speed, has the effect of lifting
the nose of the plane about the CG. With a down thrust angle, the plane
feels more stable.
- - - - Likewise, with a decrease in power from a full power condition,
the plane will want to drop it's nose. With a down thrust angle, that trim
has already been trimmed in and the effect is less diversion from horizontal
flight; i.e., a more stable airplane.
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way
back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to
Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the
main wing as well as the Horz Stab. (Of course some do have a positive
angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40
CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the
advertised HP, I'm just using a S.W.A.G. and more than likely it was
higher... Especially my re-worked engines :-)
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP
per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot
of down elevator is used to keep the plane S&L. So what happens with
Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most
people will not even notice it. And in many cases you will already be
trimmed very close to best glide SO there is less work to do when setting up
for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking
about.
If the feel is that noticeable you have some major thrust errors to correct.
[Barry] - So Gary --- I believe we agree... Just a different ways of
explaining it.
Barry
_____
From: FLYaDIVE <flyadive@gmail.com>
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: TeamGrumman-List: Engine down thrust angle
Gary & Team:
>From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is
created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator
against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust
to an engine than one with up-thrust. With up-thrust you have to fly the
plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut
there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot
of down elevator is used to keep the plane S&L. So what happens with
Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most
people will not even notice it. And in many cases you will already be
trimmed very close to best glide SO there is less work to do when setting up
for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking
about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
Message 5
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| Subject: | Re: Engine down thrust angle |
www.AuCountry.com
I just finished a major reorganization of the web site. Over 100 hours was
spent on the Restoration page alone.
________________________________
From: David Boone <david555@cox.net>
Sent: Sat, February 12, 2011 10:43:17 AM
Subject: RE: TeamGrumman-List: Engine down thrust angle
Gary, do you have a website. Thanks David
From:owner-teamgrumman-list-server@matronics.com
[mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
Subject: Re: TeamGrumman-List: Engine down thrust angle
whatever
________________________________
From:FLYaDIVE <flyadive@gmail.com>
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: TeamGrumman-List: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you
to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created
by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on
a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder,"
if you want to go fast, the horizontal needs to be flying. I.e., the elevator
needs to be lifting the plane. Or, at a bare minimum, provide a minimum down
force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or
the maintainance manual in front of me ... But you will find
the horizontal stabilizer to be in a NEGATIVE angle. This creates a down
thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center
and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out
for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area)
is pointing slightly down. Elevator trailing edge up. This varies on our
planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the
bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does
it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so
there is a balance to the See-Saw. Counter balancing the weight of the engine
and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of
the main wing. Well in this balance situation, this angle (AoI) is there to
lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are
keeping things simple so we do not have to deal with adding and subtracting
vectors. We can simply say the AoI is over coming the weight of the plane and
lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz
Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
> - - - - With a down thrust angle, less force is needed on the tail to hold
>the tail down.
[Barry] - TRUE.... That is what I said. We are saying the same thing.
>There is a lateral pivot point which balances down thrust of the
>elevator against down thrust of the engine.
> - - - - Down thrust of the engine? What are you talking about here? The
>elevator down thrust, from the classical point of view, balances the lift from
>the wing about the aircraft CG.
[Barry] - I don't think you mean to question is there such a thing as engine
down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing...
What about the weight of the engine. You have a See-Saw that balances on the
CG. But there is also the weight of the engine and thrust angle of the engine.
There is more than just lift of the wings.
>AND this is a BIG ONE - It is much easier to land a plane with down-thrust to
an
>engine than one with up-thrust. With up-thrust you have to fly the plane onto
>the runway. SO, what happens with ZERO Thrust?
> - - - - I flew the subjects plane before lowering the engine 1/2 degree.
I
>flew it after. I didn't notice any difference. It still has .3 degrees up
>thrust angle. The plane flies fine.
>
> - - - - In a landing configuration, there is so little thrust from the engine
>compared to the aircraft angle of attack as to make it a non-issue.
>
> - - - - I do agree that with and engine with several degrees of up angle
>thrust, it would be like landing down-wind.
[Barry] - We AGREE here also. Obvously the small changes you are working with
are not enough to be noticed or :-) Upset the apple cart :-)
>There is more of a neutral feel and WHICH I PREFER - And when power is cut there
>is only a small pitch change.
> - - - - Modelers that build free flight and remote control always build with
>down thrust on the engine. There is a web site for remote control plane
>builders that outlines the process for determining the optimum down thrust to
>keep the plane stable during throttle changes.
>
> - - - - With an increase in power from cruise condition, the increase in
>effective angle-of-attack due to increase speed, has the effect of lifting the
>nose of the plane about the CG. With a down thrust angle, the plane feels more
>stable.
>
> - - - - Likewise, with a decrease in power from a full power condition, the
>plane will want to drop it's nose. With a down thrust angle, that trim has
>already been trimmed in and the effect is less diversion from horizontal flight;
>i.e., a more stable airplane.
>
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back
in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to
Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main
wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn
engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP,
I'm just using a S.W.A.G. and more than likely it was higher... Especially my
re-worked engines :-)
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per
Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of
down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
> - - - - see above. I agree.
>
>When the power is cut the plane will start to balloon just a little... Most
>people will not even notice it. And in many cases you will already be trimmed
>very close to best glide SO there is less work to do when setting up for a
>landing.
> - - - - see above. I agree.
>
>NOW! ALL this information is dependent on HOW MUCH thrust we are talking
about.
>If the feel is that noticeable you have some major thrust errors to correct.
>
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining
it.
Barry
>
>
>
________________________________
>From:FLYaDIVE <flyadive@gmail.com>
>
>To: teamgrumman-list@matronics.com
>Sent:Thu, February 10, 2011 5:06:11 PM
>
>Subject: Re: TeamGrumman-List: Engine down thrust angle
>
>Gary & Team:
>
>From my experienced down thrust is a good thing ... IN MODERATION.
>
>There is a down thrust on the elevator to keep the nose up and that is created
>by the air flow.
>There is a lateral pivot point which balances down thrust of the
>elevator against down thrust of the engine.
>AND this is a BIG ONE - It is much easier to land a plane with down-thrust to
an
>engine than one with up-thrust. With up-thrust you have to fly the plane onto
>the runway. SO, what happens with ZERO Thrust?
>There is more of a neutral feel and WHICH I PREFER - And when power is cut there
>is only a small pitch change.
>With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of
>down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
>When the power is cut the plane will start to balloon just a little... Most
>people will not even notice it. And in many cases you will already be trimmed
>very close to best glide SO there is less work to do when setting up for a
>landing.
>NOW! ALL this information is dependent on HOW MUCH thrust we are talking
about.
>If the feel is that noticeable you have some major thrust errors to correct.
>Barry
>"Chop'd Liver"
>
>
>
>
>
>
>st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List
>
>tp://forums.matronics.com
>_blank">http://www.matronics.com/contribution
>
http://www.matronics.com/Navigator?TeamGrumman-List
http://forums.matronics.com
http://www.matronics.com/contribution
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