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Everything posted by iChris

  1. More than likely, what you’re looking for is in the illustrated parts breakdown or IPB. RHC calls theirs the illustrated parts catalog (IPC). if you can’t find the information there, from their official document, just call RHC tech support directly, 310-539-0508. Select tech support from the automated phone system. That’s your best bet, if all else fails. The illustrated parts catalog and maintenance manual, used in conjunction, compliment each other. R44 Illustrated Parts Catalog (IPC) See Chapter 63: Main Rotor Drive System R44 Maintenance Manual
  2. The cost-to-benefit ratio isn’t there yet. While most of those swashplate-less technologies offer advantages in rotorcraft performance, the cost of implementation has yet to reach a sufficiently low level to justify their use on production aircraft. In the design triangle options, we can normally archive any two of the sides; however, archiving all three, a bit more problematic.
  3. Most swashplate-less rotor systems, because of the required cyclical nature of control, are implemented via blade trailing edge flaps. The terms you’ll often see, Continuous Trailing Edge Flaps (CTEF) and Warping Actuated Trailing Edge Flaps make clear how the blade flapping is controlled and rotor control accomplished. While most of those swashplate-less technologies offer advantages in rotorcraft performance, the cost of implementation has yet to reach a sufficiently low level to justify their use on production aircraft. Consequently, most of the information you’re looking for is restricted to research papers and technical reports. The NASA Scientific and Technical Information Search engine at: https://ntrs.nasa.gov/search.jsp Try both search types, basic and advanced, using keywords around the subject you’re interested in. It’s also very importation to note the references at the end of each research papers or technical reports. They lead to additional information you can use. The following papers are related to your area of interest: Analysis of a Multi-Flap Control System for a Swashplate less Rotor Continuous Trailing-Edge Flaps for Primary Flight Control of a Helicopter Main Rotor Performance of Swashplateless Ultralight Helicopter Rotor with Trailing-Edge Flaps for Primary Flight Control For the advanced undergraduate and graduate students, engineers, and researchers the following level textbooks cover overall helicopter design: Principles of Helicopter Aerodynamics 2nd Edition Author: J. Gordon Leishman, University of Maryland, College Park Helicopter Performance, Stability and Control by Raymond W. Prouty Rotorcraft Aeromechanics Author: Wayne Johnson, Aeromechanics Branch of NASA Ames Research Center
  4. That’s correct, the term is “Vertical Drag” i.e. the download penalty. We assume the thrust required by the main rotor is equal to the weight of the helicopter; however, there is an additional degree of power required due to the download, vertical drag on the helicopter fuselage due to the rotors induced slipstream velocity, especially during low-speed hovering and vertical flight. The drag effect is often express as a fraction of the gross weight. Because of the download produced on the fuselage by the rotor wake, the required rotor thrust is 4% to 7% larger than the gross weight, producing a corresponding increase in required power, that’s what your 5% term relates to. There’s data available along with a number of technical papers and references. Below are two equations that yield an approximation of the vertical drag. Also, four technical references. Estimating Vertical Drag on Helicopter Fuselage during Hovering See pg. 37 - Rotary- Wing Aerodynamics Volume II - Performance Prediction of Helicopters Rotorcraft low-speed download drag definition and its reduction Principles of Helicopter Aerodynamics 2nd Edition by Gordon J. Leishman D.Sc.(Eng.) Ph.D. F.R.Ae.S.
  5. The main rotor absorbs most of the helicopters power, but there are other losses as well. The engine and transmission absorb 3% to 5% of the total power with turbine engines, or 5% to 9% with reciprocating engines. The turbine engine has larger transmission losses since its high rotational speed requires more reduction, whereas the piston engine has significant losses for cooling. The tail rotor absorbs about 7% to 9% of the total helicopter power in a hover and as much as 10% to 15% during max sideward flight to hold heading. You’ll have to see what flight regime they were testing to get that 30% number on the tail rotor. Additional loss of about 2% due to aerodynamic interference rotor-fuselage and rotor-rotor. The tail rotor and aerodynamic interference power losses are much smaller for the helicopter in forward flight. Because of the fuselage download produced by the rotor wake, the rotor thrust is 4% to 7% larger than the gross weight, producing a corresponding increase in required power. What you need to gain from this is the relationships between the dynamics, such as, how the Disk Load affects the performance and power required, not always an exact number, but an approximation. I can’t count the number of flight test that I have done, were after all the data had been compiled, the Chief Engineer (name prefixed with "Dr.") comes back and says, we don’t really understand why the data doesn’t match our calculations, we’ll need to do additional testing to understand what the dynamics are and what’s missing. In your search for exactness, don’t feel bad if it sometimes alludes you. Sometimes it’s not achievable under the circumstances.
  6. Power required by the rotor to produce thrust equal to weight can be determined from the momentum theory based on Newton’s for every action there is an equal and opposite reaction. For a helicopter in hovering flight, the action is the development of a rotor thrust equal to the gross weight. The reaction is in the acceleration of a mass of air from above the rotor to a velocity below the rotor. In other words, we need to move a mass of air equal to the gross weight each second. T= (m/sec) (∆v) or E/sec = (force) (velocity) = T v ft. lbs./sec Since 550 ft. lbs./sec is equivalent to one horsepower, the ideal power is: hp = Tv/550 since v = √DL/2p we end with the following approximation for the power required to hover (sea level) taking into account a Figure of Merit (F.M.) of 0.75. Losses that occur from the engine, transmission, tail rotor, generator, hydraulic system, etc. must be made up for by the engine and are additive to the power required by the rotor. CLICK BELOW TO ENLARGE
  7. The rotorcraft flight manual is your regulatory source for operating information. §14 CFR 91.9 Civil aircraft flight manual, marking, and placard requirements. Except as provided in paragraph ( d ) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry. §14 CFR 29.1581 General. ( a ) Furnishing information. A Rotorcraft Flight Manual must be furnished with each rotorcraft, and it must contain the following: (1) Information required by §§29.1583 through 29.1589. §29.1583 Operating limitations. §29.1585 Operating procedures. §29.1587 Performance information. §29.1589 Loading information. By the way, on which page of the TCDS did you note the conflicting information? TYPE CERTIFICATE DATA SHEET No. H10EU Model EC 155B and Model EC155B1 FAR 21.29 and FAR 29 Amendment 29-1 through Amendment 29-40..
  8. As stated above, it’s allowed to Hunt (Drag), Flap, and Feather (Pitch change) Starflex Hub Dynamics
  9. The last word was under FAA notice N 8900.320, listed in part below. For the latest contact, Shawn Hayes in the Airmen Certification and Training Branch (AFS-810) at (202) 267-0863 or via email at shawn.hayes@faa.gov. 7 a. Person Who is Authorized by the FAA. For the purposes of § 61.195(k)(7), the FAA considers “a person who is authorized by the FAA to provide that logbook endorsement” as a person who holds one of the following positions and meets the requirements of subparagraphs 7b and 7c. These FAA programs under which these individuals hold their positions are the means by which the FAA can maintain oversight of the authorized NVG endorsement function. (1) A Designated Pilot Examiner (DPE). (2) A chief instructor, assistant chief instructor, or check instructor operating in an approved 14 CFR part 141 NVG course, when properly qualified in that course. Note: Because § 61.195 addresses the limitations and qualifications of certificated flight instructors under part 61, check pilots under 14 CFR part 135 and Training Center Evaluators (TCE) under 14 CFR part 142 will not be authorized to provide the endorsement required by § 61.195(k)(7). These individuals, if properly authorized, may still be considered authorized instructors for the purpose of providing NVG training and endorsements required by § 61.31(k)(1) or (2). 7 b. Qualifications for a Person Who is Authorized by the FAA to Issue the Logbook Endorsement Required by § 61.195(k)(7). (1) Personnel must be able to show that they meet the requirements of § 61.195(k)(1)–(6) in order to initially receive authorization to issue the logbook endorsement required by § 61.195(k)(7), and must continue to meet these requirements in order to maintain authorization. (2) Personnel must meet the requirements of subparagraph 7a. (3) Personnel must be authorized in writing by the Administrator, as outlined below, in order to issue the logbook endorsement required by § 61.195(k)(7). 7 c. Authorization in Writing. The authorization to issue the logbook endorsement required by § 61.195(k)(7) must be accomplished by the method described below. Only the Administrator can issue the authorization to give the endorsement required by § 61.195(k)(7). The LOA will be issued using the Web-based Operations Safety System (WebOPSS) when issuing an FAA authorization to an individual to issue the pilot logbook endorsements required by § 61.195(k)(7), provided he or she meets the requirements of this notice. Appendix A, Sample LOA B011, Authorization to Issue the Logbook Endorsement Required by 14 CFR § 61.195(k)(7): 14 CFR Part 61, has an example of the LOA that will be generated in WebOPSS. 9. Disposition. This is a special-emphasis notification. The Flight Standards Service (AFS) will incorporate the information in this notice into Order 8900.1 before this notice expires. In addition, AFS is in the process of publishing additional guidance regarding the certification of airmen wishing to utilize NVGs. This will include an advisory circular (AC) and an update to Order 8900.1. Direct questions pertaining to the information in this notice to Shawn Hayes in the Airmen Certification and Training Branch (AFS-810) at (202) 267-0863 or via email at shawn.hayes@faa.gov.
  10. Too much left pedal applied following the throttle chop or lack of right pedal, #1 common error. Moreover, just too much positive tail rotor pitch remaining vs. the level of torque. Power Failure in a Hover, Common Errors: 1. Failure to use sufficient proper anti-torque pedal when power is reduced. 2. Failure to stop all sideward or backward movement prior to touchdown. 3. Failure to apply up-collective pitch properly, resulting in a hard touchdown. 4. Failure to touch down in a level attitude. 5. Failure to roll the throttle completely to idle. 6. Failure to hover at a safe altitude for the helicopter type, atmospheric conditions, and the level of training/ proficiency of the pilot. 7. Failure to go around if not within limits and specified criteria for safe autorotation. REF: Helicopter Flying Handbook Page 11-7 Chapter 11: Helicopter Emergencies and Hazards
  11. Too much left pedal applied during the torque reduction. The answer is already in your question, “we don't have the torque effect to counter.” The answer is also in the needle split you see on your dual tac when you rolled off the throttle. Tail rotor thrust is a function of rotor RPM and the torque couple is a function of engine RPM. You were in equilibrium before you rounded off the throttle, tail rotor thrust equal to the main rotor torque couple. What happen? It’s right there on your dual tac. Again, from your question, “we don't have the torque effect to counter.” Clue, after the throttle chop, the engine RPM reduction leads rotor RPM reduction. The effect, the torque couple is decreasing faster than the reduction in tail rotor thrust required to maintain equilibrium. Therefore, what do you need to do? Reduced tail rotor thrust (tail rotor pitch) with right pedal; thereby, regaining equilibrium and arresting the left yaw. In other words, you need to compensate for the reduction in torque with a reduction in anti torque.
  12. The simplified dynamic behavior of the airframe can be represented by a spring K and a weight M suspended from the rotor, which excites the airframe at a frequency of 3w (three blade system). The response of the weight M to this excitation (load F1) varies with M and with the natural frequency of the spring, a function of M and the spring stiffness. Therefore, depending on the airframe dynamics (M and K), the vibrations will either be amplified or attenuated but they will always be present. If a weight m is now added via a spring k to weight M (m < M), the vibration characteristics are altered. Weight m is excited by weight M but it counteracts and tends to reduce the excitation load F0. It can even cancel it out if the resonator's natural frequency is equal to the 3w excitation. If the resonator (damping system) frequency is equal to the excitation frequency, the airframe does not respond since the weight M does not vibrate, i.e. the damping system cancels out the vibrations. The AS350 diagrams are from an old Eurocopter systems training manual. The older manuals contained more technical information while the newer manuals became more operational than technical. The Bell drawings were from the B407 maintenance manual. A practical example of these TMD principles can be seen in the following YouTube video. '>https://youtu.be/f1U4SAgy60c
  13. The FRAHM damper is named after its inventor, Hermann Frahm. Its common application, with regard to helicopter rotor systems, is often referred to as a Tuned Mass Damper (TMD). It consists of an oscillating weight, mass, which is attached to the main rotor system, setup in a way that the number of degrees of freedom and therefore the number of resonances of the complete system are dissipative. A weight is located on the rotor hub axis and is held by springs allowing it to vibrate in the horizontal plane and in the other directions. The weight/spring system is excited by the periodic cyclic loads on the rotor hub and responds at the excitation (tuned) frequency thereby counteracting the excitation, absorbing rotor hub vibration. In other words: Ideally, the frequencies and amplitudes of the damper system and the main rotor should nearly match so that every time the rotor pushes one way, the damper system creates an equal and opposite push the other way, keeping the rotor system horizontal displacement at or near zero. There’re a number of different system out there, the names and terms are many, this is just one of many. Examples of rotor hubs below are the AS350 and Bell 407. You can view Frahm’s 1911 patent drawing at: http://www.freepatentsonline.com/0989958.pdf
  14. Eric Hunts post above stated the main reasons for these endplates. Rather than being directly behind the fuselage and rotor hub, some engineers found that placing vertical endplates on the end of the horizontal stabilizer made for a more effective horizontal stabilizer and vertical endplate, since the endplate is out in relatively cleaner air. The vertical endplates being displaced from the tail rotor, also minimized their effect on tail rotor flow patterns. These vertical endplates aid in unloading the tail rotor thereby further reducing tail rotor flapping in forward flight. Furthermore, endplates are often incorporated to address directional stability issues. Engineers have difficulty predicting analytically whether a design will be stable or unstable. The aerodynamic environment at the tail rotor and empennage are influenced by the disturbances produced by the main rotor and fuselage. As an example, this helicopter with SAS off, Dutch roll was unstable without endplates on the horizontal stabilizer but stable when small canted endplates were installed. The dramatic change in stability was much more than could be predicted by any known analytical method and must be attributed to some peculiar flow conditions in the main-rotor wake. In the final design, they went from the T-Tail to a conventional horizontal stabilizer and found endplates were not necessary. Overall design considerations, trade-offs, advantages, and disadvantages along with flight test, weigh-in to determine whether endplates are necessary.
  15. Your responsibilities started before you turned the key. So I guess, you can log flight time during your preflight inspection. If responsibilities are the only criteria to substantiate logging flight time, why not. §91.7 Civil aircraft airworthiness. ( a ) No person may operate a civil aircraft unless it is in an airworthy condition. ( b ) The pilot in command of a civil aircraft is "responsible" for determining whether that aircraft is in condition for safe flight…
  16. Northwest Helicopters can point you in the right direction Address: 1000 85th Ave SE, Olympia, WA 98501 Phone: (360) 754-7200 The reason you might be having a hard time finding somebody that provides UH-1 (restricted category) helicopter training Is because, most don’t advertise that fact outright, that they’re willing to provide such training for compensation to the general public. However, Bell 204/205 (normal category) training for all practical purposes is the same and doesn’t have to be done under the table. Be aware, that when you’re receiving flight training in a restricted category aircraft (i.e. UH-1), for compensation, and the flight training is just general flight training, the owner operator is fudging the rule a little bit. The only training that you can legally provide in a restricted category aircraft, is flight crewmember training in the specific special operations for which the aircraft is certificated. §91.313 Restricted category civil aircraft: Operating limitations.
  17. Getting back to the original posters question, your employer isn’t concerned with how you log PIC time in your personal logbook. If your employer had any real issues with your logbook or the way you log, he wouldn’t have hired you in the first place. He’s not really concerned with the .2 or .3 additional you may have logged. Your employer is most concerned with the aircraft’s time in service. He’s at the other end of the spectrum. The owner wants to make sure that extra .2 or .3 doesn’t make its way into the maintenance log. That extra time in service cuts into the owner’s bottom line $. So, as most owners see it, if the customer sometimes pays for an extra .2 or .3 and/or the pilot logs a little more PIC time, so be it, that’s the way of the industry. Owners base their operating cost on time in service. Furthermore, if they bill from a customer’s meter (i.e. engine on - engine off), that .2 or .3 is just extra icing on the cake for the owner that customer/student pay for and the pilot/flight instructor benefits from. § 1.1 Time in service means: with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing. § 1.1 Flight time means: Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing… “Existing regulations, specifically 14 C.F.R. § 91A17( a )(2)(i), require each owner or operator to keep records containing the total time in service of the airframe, each engine, each propeller, and each rotor. This is accomplished by the owner or operator recording and tracking in some form and manner the time in service of the airframe, engines(s), propeller(s), and rotor(s) from the moment the aircraft leaves the surface of the earth until it touches it at the next point of landing, as referenced in 14 C.F.R. § 1.1. In addition, § 91.417( a )(2)(ii), and similar provisions in 14 C.F.R. §§ 121.380( a )(2)(iii) and 135.439( a )(2)(ii), require owners or operators (certificate holders) to keep records that show the current status of life-limited parts of each airframe, engine, propeller, rotor, and appliance.” - Office of the Chief Counsel, Jul 8, 2009
  18. What's the problem? Are you getting a needle split? With N1 @ 72% an, unloaded N2 (rotor in autorotation) could run 6000 - 6100 RPM. What you should be concerned with is your rotor RPM in autorotation, within correct range, per maintenance manual.
  19. This is generally not an RC Forum, as stated above. However, try these basics. RC helicopters incorporate the following components: -Battery -Motor -ESC (electronic speed control) -Radio receiver -Servos The battery supplies the required power for each component. The ESC is connected to the servo channel on the radio receiver and rather than controlling the position of the servos alone, the radio receiver through the ESC, also controls the speed and torque of the electric motor by electronically selecting between the three sets of windings in the motor. After drying it out, the next thing to look for, before ever connecting the battery, is corrosion. Check for corrosion around all electrical components, wiring, connectors, and especially the motor. Depending on the level of corrosion, if found, you may be able to save some of your components. Try some CorrosionX products. More than likely your battery was completely drained well before corrosion set in, which would’ve precluded any electrical shorting; therefore, most of your sealed electronics are still good, i.e. your ESC. Try a known good battery. The most likely culprit is your battery. The batteries used in most RC helicopters are multi cell batteries. These batteries do not like to be completely discharged and left in that state for long periods. Even though you may have charged the battery and it appears good and shows the correct voltage, one or more cells are likely bad and that battery is unusable under the full load of your RC. The motor can be checked, depending on type, Brushed motor (two-wire) or Brushless motor (three-wire). For the two wire motors, just connect the two-wires of the motor to a good battery using test clips. If it’s good, it should turn freely. For or a three-wire motor, you could use your multi-meter to check for open windings between phases, using the ohm setting. However, most failures are due to shorted windings caused by corrosion or overheating, your multi-meter won’t help much, due to the inherent low resistance. What you need is an inductance/capacitance meter (LC meter) to identify a bad phase in the motor. Since you don’t have an LC meter, what you can do is, use your cordless drill or DREMEL tool to drive the shaft of the motor, turning it into a generator. Then connect your multi-meter, set on the AC mV range, across all three phases (wires) of the motor (i.e., Red-Grn, Red-Blk, Blk-Grn). If the motor is good, all three phases should generate approximately the same AC voltage.
  20. Let's define terms; “Phase lag” is the delay between cause and effect. The Effect: We have a rotor system that responds to our input a time later (delay) after we’ve made them and in a different position ahead of our initial input. The Causes: Aerodynamic Forces, Centrifugal Forces, Weight (mass), and Inertial Forces. Gyroscopic Forces are in order, to simplify the explanation, because any rotating mass exhibits similar properties to that of a gyro. The rotor disk as a rotating body exhibits an ability to maintain its angular momentum and maintain its direction in space, however weak. In doing so, aerodynamic forces, centrifugal forces, weight, and inertial force are the primary causes of flapping action. Also, hingeless rotors or rigid rotors may have no single point at which flapping occurs, but an “Effective Hinge Offset” can be determined that will give the same characteristics as a blade with an actual mechanical hinge at that point. Remember, bending and flexing along defined points along the blade accomplishes flapping on a rigid rotor system.
  21. Gyroscopic procession as referred to in most standard textbooks, is a simplified way of explaining the motion of a helicopters rotor as it turns. As a quote from Aristotle: “It is the mark of an instructed mind to rest satisfied with that degree of precision which the nature of the subject admits, and not to seek exactness where only an approximation of the truth is possible.” If we seek exactness, the rotor is not a gyro and the rotor flapping is not a pure precession as in “Gyroscopic Precession.” However, the rotor system exhibits “similar properties” since its part of the same family of mechanics. When a control input is applied that increases the blade pitch at a given point the blade will have its maximum flapping amplitude sometime later in the direction of rotation. We had a post on this subject back in 2010 at link: Gyroscopic Precession, Nov. 2010 However, we can wrap this up quickly if we look at some of the basic forces. When we look at the forces acting on the rotor: 1. Aerodynamic forces 2. Weight forces (mass) 3. Inertia forces 4. Centrifugal forces (Centripetal force if you prefer) vs. When we say "Gyroscopic Forces" lets list some: 1. Weight (mass) 2. Inertia forces 3. Centrifugal Forces (Centripetal force if you prefer) If the forces aren't equal the mechanics of motion aren't equal. Our rotor has one additional force that sets It apart from a Gyro and the Gyro lacks this force. Aerodynamic forces are what sets the rotor apart from the Gyro. If you took away the aerodynamic forces, essentially placing a rotor in a vacuum, the rotor would then behave like a gyroscope.
  22. Question 18x on the medical: Other illness, disability, or surgery If you’re not substantially impaired by this sleep apnea, and there’s no record of diagnosed Obstructive or Central Sleep Apnea, and you’ve never established yourself, in writing, as having Obstructive or Central Sleep Apnea, your answer should be “No” by definition of the meaning “disability” (see quote below). The fact that you’re seeking a disability claim doesn’t constitute a disability diagnosis. A record of medical diagnosis must validate the claim. It appears that you have no record of testing, diagnosis, or even completing a Polysomnogram to support an Obstructive Sleep Apnea claim presently. If so, the answer to 18x is “No”. However, once a positive diagnosis is confirmed by a Physician, you’ll have to answer “Yes”. Until that time, answering “No” is not in violation (Perjury).
  23. Take a look at questions 17 -19. Those are the key medical question. Don’t add additional answers to questions not asked. Don’t be afraid to just answer “No”. If you were never official diagnosed by a doctor of a listed condition, the answer is “No”. However, if you voluntarily add you were treated for one of the three types of sleep apnea, you'll force your AME to made a risk assessment based on one of the six groups below. This is the new screening guidance for AMEs. If the AME is in agreement with you, that the condition is mild, medical issuance shouldn’t be a problem. Applicant Previously Assessed: Group 1: Has OSA diagnosis and is on Special Issuance. Reports to follow. Group 2: Has OSA diagnosis OR has had previous OSA assessment. NOT on Special Issuance. Reports to follow. Applicant Not at Risk: Group 3: Determined to NOT be at risk for OSA at this examination. Applicant at Risk/Severity to be assessed: Group 4: Discuss OSA risk with airman and provide educational materials. Group 5: At risk for OSA. AASM sleep apnea assessment required. Applicant Risk/Severity Extremely High: Group 6: Deferred. Immediate safety risk. AASM sleep apnea assessment required. Reports to follow. Video Link - Screening Guidance for AMEs John King Hits FAA Medical Inflexibility
  24. Many may remember Mike Smith, he was in a wheel chair, but piloted a Bell 206 with special controls flying air attack and aerial mapping missions for the US Forest Service, (Region 4). AOPA did a story on him. I don’t know if he’s still around, haven’t seen him recently. Link: PILOTS MIKE SMITH AOPA February 5, 1999 Link: New Hand Controls Allow the Disabled to Fly
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