Full power takeoff!

Mayfield

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I'm trying to understand this discussion. Is the problem not that the 915 is too powerful for this aircraft, and if one does choose to install a 915 one should use no more power on takeoff than what the aircraft was originally designed for? Seems to me it's not a fault of the aircraft design rather an indication that the aircraft should be redesigned to accommodate the more powerful engine.
Hi Jeff,
I believe it is simply that some pilots don't understand that we as pilots are always required to use power on an "as required" basis. Whether you are flying a tired C-150, an airplane with a R-2800-18W like Jon talked about earlier, or a 915 Rotax you should use power as required by the circumstances.

With the O-200 engine in the C-150 you could probably just shove the throttle forward and have time for a sandwich and a Pepsi before takeoff. With the higher output engines, things happen somewhat more quickly.

Pilots get in trouble when they forget that the throttle, or power lever, is not an on/off toggle. Rather than limit the power to what the aircraft was originally designed for, limit your use of power to what is required, or desired, at the moment. Vance summed it up quite nicely when he described the effect of airspeed on control effectiveness.

Jim
 

Jean Claude

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Rather than limit the power to what the aircraft was originally designed for, limit your use of power to what is required, or desired, at the moment.
If the aircraft was not designed for this new power, then is it acceptable to sell it anyway?
 

Abid

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I'm trying to understand this discussion. Is the problem not that the 915 is too powerful for this aircraft, and if one does choose to install a 915 one should use no more power on takeoff than what the aircraft was originally designed for? Seems to me it's not a fault of the aircraft design rather an indication that the aircraft should be redesigned to accommodate the more powerful engine.

It is not too powerful. The aircraft rigging and design stops have to be correct and the pilot needs transition to it and get familiar with the power available and its effects. Obviously the aircraft design needs to accommodate the heavier more powerful engine. You do have to do some changes to get that done
 

BEN S

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Jeff it akin to selling a first time rider a Kawasaki H2 with 200 hp that weighs around 300lbs.
Then telling him, "just don't crack the throttle too much or too quick"
Accident reports will play out that very few are able to heed the warnings until the learning curve has kicked in.
Thats why Insurance rates on hyperbikes for young guys is so expensive.

Is it right? Or is it A right?
 

Mayfield

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If the aircraft was not designed for this new power, then is it acceptable to sell it anyway?
I guess my point was that an airframe can have many engine/propeller combinations and still be acceptable with minimal modification. The lowly C-172 was first offered with 145 HP, then 160 HP then 180 HP. The airframe mods were minimal.

I see you fly the Jodel D.117, a derivative of the D.11 with many, many engine variations.

Probably the best example, in light aircraft, would be the Piper Cub. I have personally flown cubs with 40 through 250 horsepower. Yes, airframe mods were sometimes required, but the mods are usually minimal and focused on CG and structure upgrades required to handle the different weight and Power of the engine variants.

So, I guess the direct answer to the question posed above is "no", if the airframe is not suitable for the different power plant and "yes" if the aircraft is safe with the new power plant. Testing, and structural analysis should determine the appropriateness of the new offering.

Jim
 
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Vance

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If the aircraft was not designed for this new power, then is it acceptable to sell it anyway?
I feel I have failed to communicate.

The 915 Cavalon I flew appeared to me to be well designed.

I suspect it had a complete flight test program before it was released for sale to the public.

In my experience it does not take any special skills to fly a 915 powered Cavalon.

The fact that pilots may apply full power prematurely combined with full rudder deflection without serious consequences is a testament to the quality and forgiving nature of the design of the Cavalon.

I feel this sort of piloting will work till it doesn't.
 

Mayfield

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I feel I have failed to communicate.

The 915 Cavalon I flew appeared to me to be well designed.

I suspect it had a complete flight test program before it was released for sale to the public.

In my experience it does not take any special skills to fly a 915 powered Cavalon.

The fact that pilots may apply full power prematurely combined with full rudder deflection without serious consequences is a testament to the quality and forgiving nature of the design of the Cavalon.

I feel this sort of piloting will work till it doesn't.
Hi Vance,
I think Ben's analogy above is also spot on. When you raced Bikes on the Isle of Man, the bike you rode was probably well engineered to the task and the "pilot" was familiar with the machine. It would probably have been legal to sell that bike to some Testosterone laden young buck and wave goodbye, but you didn't, at least in part, because you knew he would break his fool neck.

I have heard stories about Abid turning down sales because he didn't get a good vibe about the capabilities of potential buyers. Ernie Boyette did the same thing. You probably remember me telling you stories about students who gave it their best shot, but just didn't pack the gear to fly any aircraft. Those were always difficult conversations. It is unpleasant to dash someone's lifelong dream. Not, however, as unpleasant as calling their wife while the column of black smoke is still rising.

So. In my opinion, there is nothing wrong with selling higher powered gyros, crotch rockets, or an AR that is properly engineered and tested. I applaud manufacturers that attempt to school customers on the idiosyncrasies of the product.

I think you explained it very well.

Jim
 
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MikeBoyette

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Jim,
I was witness to many a conversation between Dad and a potential customer who was told to take up golf. I knew one student while I was working on getting my certificate I nicknamed “Boatman”. The instructor had almost 50 hours with this guy before he finally told him “listen I can’t take anymore of your money. You just will never be a pilot”. He finally understood and found his joy doing something else after thanking all of us for treating him like family.
 

Jean Claude

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Not all users buy directly from a manufacturer. Very often, there are one or more intermediate resellers.
Just my opinion.
 
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Mayfield

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Not all users buy directly from a manufacturer. Very often, there are one or more intermediate resellers.
Just my opinion.
I apologize Jean Claude. I did not understand your question.

I would have to say, I don't know.

I have heard, in this country, there are liability laws that could make it problematic to sell an experimental aircraft that subsequently fails or crashes, because of some flaw. I have no personal knowledge of such a lawsuit or prosecution.

Morally? That is a different question. Ben alluded to the morality question in post 44 and I missed his point until now.

Jim
 

jeffh

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Hi Jeff,
I believe it is simply that some pilots don't understand that we as pilots are always required to use power on an "as required" basis. Whether you are flying a tired C-150, an airplane with a R-2800-18W like Jon talked about earlier, or a 915 Rotax you should use power as required by the circumstances.

With the O-200 engine in the C-150 you could probably just shove the throttle forward and have time for a sandwich and a Pepsi before takeoff. With the higher output engines, things happen somewhat more quickly.

Pilots get in trouble when they forget that the throttle, or power lever, is not an on/off toggle. Rather than limit the power to what the aircraft was originally designed for, limit your use of power to what is required, or desired, at the moment. Vance summed it up quite nicely when he described the effect of airspeed on control effectiveness.

Jim
Thanks, pretty much in agreement with you and Vance, I think what I was alluding to is that if one has an aircraft that has power that can test the limits of it's control surfaces on takeoff, one should either limit the power on takeoff, or redesign the aircraft so that the control surfaces are not at their limit when at full power, to allow for a margin of safety. As you say, in many aircraft the concept of applying full power on takeoff is considered standard, but that's not necessarily a rule that should be applied to all aircraft, particularly if the power plant has been upgraded significantly beyond that which was tested with the original design. From this I have a question - has the Operating Manual of the Cavalon 915 or the MTO 915 for that matter, been changed from the standard 912/914 operating manual to limit power on takeoff rather than going to full power as in the previous operating manuals?
 

Vance

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AutoGyro_POH_Cavalon 915iS Revision 1.0 – Issue Date 08.MAY.2019

The manual is not a substitute for competent theoretical and practical training on the operation of this aircraft. Failure to adhere to its provisions or to take proper flight instruction can have high-risk consequence

4.1 Airspeeds for Safe Operation Climb … 116 km/h (70mph, 60KIAS) IAS

Best rate of climb / best endurance... 100 km/h (60mph, 50KIAS) IAS

Best range ... 110 km/h (70mph, 60KIAS ) IAS

Approach ... 100 km/h (60mph, 50KIAS) IAS

4.8 Take-off Procedure

Check relative wind

With right hand, maintain control stick in a forward position

Switch pneumatic mode selector to FLIGHT and return to brake with left hand

Hold wheel brake without having locking pawl engaged

While holding wheel brake adjust throttle to give 2000 RPM

Activate and hold pre-rotator.

To reduce lateral stick force during prerotation, adjust the forward stick position by pulling it slightly aft and to the right

Let pneumatic clutch fully engage (stabilization at about 100 rotor RPM).

If necessary release pre-rotator button momentarily and press again to maintain engine RPM within green arc, respectively to prevent engine from stalling!

Carefully increase throttle to increase rotor rpm to that required for the take-off.

Minimum rotor rpm for take-off is 200, maximum achievable is 320. Between 280 and 320rpm it is possible that the high engine rpm and resultant propeller static thrust generated may be causing the aircraft to slide with wheels locked – depending on the runway surface and payload.

If sliding starts reduce power! If the rpm is not sufficient for take-off, abort and restart as required. In case of a slipping clutch (CLUTCH light), reduce power and match engine rpm to rotor rpm. When the minimum required rotor rpm is reached, release pre-rotator button.

Gently - but smartly - move control stick fully aft (stick travel ~ 1 sec.), see 4.9

In a strong headwind be prepared to stop movement as the nose wheel rises! Release wheel brake with throttle unchanged

Monitor rotor speed and progressively increase throttle to take-off power

If the CLUTCH light is flashing, check that the rotor rpm is sufficient and considerØ aborting the take-off run.

4.9 Take-off Run

Check engine has reached full power for take-off. Otherwise, abort take-off

Commencing the take-off run with high rotor rpm (280-320) and the stick fully back means that there is a high starting drag load. The aircraft has to accelerate to approx. 50mph (depending on loading) to take off, and achieve the rotor rpm for the loading conditions. Therefore, to minimise the drag and enable maximum acceleration at high rotor rpm, move the stick forwards to approximately the mid position as the aircraft starts to move. Monitor rotor rpm carefully ensuring that it is increasing, if the stick is too far forwards the rotor rpm will decay, and a serious accident can be caused!

When the nose comes up allow nose wheel to float at about 10 – 15 cm above the runway by a balanced change of control stick position

Minimize lateral drift by applying appropriate lateral control stick input into cross wind direction Maintain directional control i.e. runway alignment with sensitive pedal input

Maintain attitude until speed increases and gyroplane lifts off (at about 80kmh (50mph, 45KIAS), depending on loading and rotor)

Allow gyroplane to build-up speed in ground effect

4.10 Climb

Perform initial climb at safe climb speed and adjust trim

Set power to maximum take-off power. CAUTION Full take off power will require right rudder input to counteract the high thrust and torque load.

Check engine instruments and respect maximum take-off power time limit

Switch off second fuel pump at safe height

At safe altitude, the climb may be continued with VY and reduced power setting for noise abatement When desired altitude is approached, level gyroplane and reduce power
 

jeffh

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AutoGyro_POH_Cavalon 915iS Revision 1.0 – Issue Date 08.MAY.2019

The manual is not a substitute for competent theoretical and practical training on the operation of this aircraft. Failure to adhere to its provisions or to take proper flight instruction can have high-risk consequence

4.1 Airspeeds for Safe Operation Climb … 116 km/h (70mph, 60KIAS) IAS

Best rate of climb / best endurance... 100 km/h (60mph, 50KIAS) IAS

Best range ... 110 km/h (70mph, 60KIAS ) IAS

Approach ... 100 km/h (60mph, 50KIAS) IAS

4.8 Take-off Procedure

Check relative wind

With right hand, maintain control stick in a forward position

Switch pneumatic mode selector to FLIGHT and return to brake with left hand

Hold wheel brake without having locking pawl engaged

While holding wheel brake adjust throttle to give 2000 RPM

Activate and hold pre-rotator.

To reduce lateral stick force during prerotation, adjust the forward stick position by pulling it slightly aft and to the right

Let pneumatic clutch fully engage (stabilization at about 100 rotor RPM).

If necessary release pre-rotator button momentarily and press again to maintain engine RPM within green arc, respectively to prevent engine from stalling!

Carefully increase throttle to increase rotor rpm to that required for the take-off.

Minimum rotor rpm for take-off is 200, maximum achievable is 320. Between 280 and 320rpm it is possible that the high engine rpm and resultant propeller static thrust generated may be causing the aircraft to slide with wheels locked – depending on the runway surface and payload.

If sliding starts reduce power! If the rpm is not sufficient for take-off, abort and restart as required. In case of a slipping clutch (CLUTCH light), reduce power and match engine rpm to rotor rpm. When the minimum required rotor rpm is reached, release pre-rotator button.

Gently - but smartly - move control stick fully aft (stick travel ~ 1 sec.), see 4.9

In a strong headwind be prepared to stop movement as the nose wheel rises! Release wheel brake with throttle unchanged

Monitor rotor speed and progressively increase throttle to take-off power

If the CLUTCH light is flashing, check that the rotor rpm is sufficient and considerØ aborting the take-off run.

4.9 Take-off Run

Check engine has reached full power for take-off. Otherwise, abort take-off

Commencing the take-off run with high rotor rpm (280-320) and the stick fully back means that there is a high starting drag load. The aircraft has to accelerate to approx. 50mph (depending on loading) to take off, and achieve the rotor rpm for the loading conditions. Therefore, to minimise the drag and enable maximum acceleration at high rotor rpm, move the stick forwards to approximately the mid position as the aircraft starts to move. Monitor rotor rpm carefully ensuring that it is increasing, if the stick is too far forwards the rotor rpm will decay, and a serious accident can be caused!

When the nose comes up allow nose wheel to float at about 10 – 15 cm above the runway by a balanced change of control stick position

Minimize lateral drift by applying appropriate lateral control stick input into cross wind direction Maintain directional control i.e. runway alignment with sensitive pedal input

Maintain attitude until speed increases and gyroplane lifts off (at about 80kmh (50mph, 45KIAS), depending on loading and rotor)

Allow gyroplane to build-up speed in ground effect

4.10 Climb

Perform initial climb at safe climb speed and adjust trim

Set power to maximum take-off power. CAUTION Full take off power will require right rudder input to counteract the high thrust and torque load.

Check engine instruments and respect maximum take-off power time limit

Switch off second fuel pump at safe height

At safe altitude, the climb may be continued with VY and reduced power setting for noise abatement When desired altitude is approached, level gyroplane and reduce power
So this is where I have the question in section 4.9 'Check engine has reached full power for take-off. Otherwise, abort take-off'
Why is it necessary to achieve full power on a standard field takeoff when this can get one in trouble (as I assume the controls are close to full deflection in a 915 powered Cavalon) when it is well accepted that the Cavalon can take off quite adequately with the power levels achieved with a 912/914. My assertion is that it is safer to take off with less than full power, as long as the power is adequate.
 

Vance

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So yes from 100 feet off the ground I was choosing to be in a max steep climb, as the instructor did. Yes, we are all at the full right rudder.
At 100 feet and full power, I've practiced reducing power as if hit by a gust of wind many many times. At 100 feet it is a non-event, in my opinion. Please explain where I'm wrong.

It is so much worse flying by myself. I fly her off at 4600 RPM and initial climb at 5300 in Cavalon 915s when flying alone. But at 100 feet I'm at full power and full right rudder. 100 feet is a lot of time to recover in a gyroplane especially when you are maintaining 80MPH climb.
Full right rudder deflection at 70kts indicated air speed?

I did not read you words carefully enough and misunderstood your posts John, I thought you were reaching full rudder deflection briefly during the climb out.

Now that I understand you press the right pedal to the floor and leave it there climbing out twenty knots above best rate of climb feeling that you can manage a power interruption or a wind change at 100 feet above the ground I realize my words will have no meaning to you.

In my experience full rudder deflection at 70kts indicated airspeed in a Cavalon would result is dangerously uncoordinated flight no matter what the power setting is.
 
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Vance

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So this is where I have the question in section 4.9 'Check engine has reached full power for take-off. Otherwise, abort take-off'
Why is it necessary to achieve full power on a standard field takeoff when this can get one in trouble (as I assume the controls are close to full deflection in a 915 powered Cavalon) when it is well accepted that the Cavalon can take off quite adequately with the power levels achieved with a 912/914. My assertion is that it is safer to take off with less than full power, as long as the power is adequate.
I agree jeffh.

I am not sure what their definition of full power is or how they measure it.

In The Predator I have a minimum takeoff engine rpm of 2,300 and anything below that I advise aborting the takeoff.

Full power is 2,700 engine rpm.
 
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Jean Claude

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I guess my point was that an airframe can have many engine/propeller combinations and still be acceptable with minimal modification. The lowly C-172 was first offered with 145 HP, then 160 HP then 180 HP. The airframe mods were minimal.

I see you fly the Jodel D.117, a derivative of the D.11 with many, many engine variations.

Probably the best example, in light aircraft, would be the Piper Cub. I have personally flown cubs with 40 through 250 horsepower. Yes, airframe mods were sometimes required, but the mods are usually minimal and focused on CG and structure upgrades required to handle the different weight and Power of the engine variants.

So, I guess the direct answer to the question posed above is "no", if the airframe is not suitable for the different power plant and "yes" if the aircraft is safe with the new power plant. Testing, and structural analysis should determine the appropriateness of the new offering.

Jim
My point was that the installer of a more powerful motor on an airframe must ensure that this modification will not be a dangerous surprise to the user, and will not require special training for each model.
A pilot trained on a 100 hp Morane Saulnier 880 "Rallye" can without any risk leave alone on a Morane Saulnier 893 "Commodore" 1.8 times more powerful. When only 1.15 times more power on some gyroplanes already seems to be a problem for users, then It seems to me that this is a design carelessness
Sans titre.png
 

Mayfield

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My point was that the installer of a more powerful motor on an airframe must ensure that this modification will not be a dangerous surprise to the user, and will not require special training for each model.
A pilot trained on a 100 hp Morane Saulnier 880 "Rallye" can without any risk leave alone on a Morane Saulnier 893 "Commodore" 1.8 times more powerful. When only 1.15 times more power on some gyroplanes already seems to be a problem for users, then It seems to me that this is a design carelessness
View attachment 1156057
Thanks Jean Claude,

I understand.

Jim
 

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Full right rudder deflection at 70kts indicated air speed?

I did not read you words carefully enough and misunderstood your posts John, I thought you were reaching full rudder deflection briefly during the climb out.

Now that I understand you press the right pedal to the floor and leave it there climbing out twenty knots above best rate of climb feeling that you can manage a power interruption or a wind change at 100 feet above the ground I realize my words will have no meaning to you.

In my experience full rudder deflection at 70kts indicated airspeed in a Cavalon would result is dangerously uncoordinated flight no matter what the power setting is.

I do not think you should even be putting in full deflection on rudder at 70 knots. That just does not seem right but I have not flown 915 powered Cavalon. Generally in airplanes there will be a maneuvering speed beyond which big deflection and definitely full deflections are prohibited. In gyroplanes although we do not have technically a "maneuvering speed" as such but certainly beyond 55 - 60 knots putting full deflection to the stop is not advisable.
Now if John is saying that he needs full deflection just to fly it co-ordinated in a 70 knot climb out on Cavalon 915, I am baffled.
 

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...or seriously cross controlled, and not co-ordinated.:)
 
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