• IVOPROP Quick Ground Adjustable Ultralight Propeller
• Ultralight:
• Up to 72" diameter. For engines up to 100 hp. 18"-52" or 35"-70" pitch range. 48"-72" diameter
• Schoeffmann's blades are 72" long and are the Ultralight. I forgot to ask which pitch range he got.
• Which pitch range is wanted? It is looking like 18"-52"
• 2-blade. 6 lb. $440.00
• 3-blade. 8 lb. $600.00
• This suggests that the blades weigh 2.0 lbs each and the hub weighs 2.0 lbs. See below for more.
• 14.9" (378.9mm) 'hub-bar' will result in a 7-1/4 ft rotor diameter. This is the current design.
• 24" 'hub-bar' will result in an 8 ft rotor diameter.
• 36" 'hub-bar' will result in a 9 ft rotor diameter.
• Schoeffmann's blades are 72" long.
• 3 blades per rotor will reduce the vibration, should it be significant.
• Medium:
• Up to 74" diameter. For engines around 100 hp or high ratio gearboxes. 30"-90" pitch range. 52"-74" diameter
• 2-blade. 11.2 lb. $820.00
• 3-blade. 14.2 lb. $1060.00
• This suggests that the blades weigh 3.0 lbs each and the hub weighs 5.2 lbs.
• 24" 'hub-bar' will result in an 8'-2" rotor diameter.
• 36" 'hub-bar' will result in an 9'-2" rotor diameter.
• Magnum:
• up to 74" diameter For engines up to 700 hp. 30"- 90" pitch range . 58"- 76" diameter
• 2-blade. 17.5 lb. $1080.00
• 3-blade. 22.3 lb. $1400.00
• This suggests that the blades weigh 4.8 lbs each and the hub weighs 7.9 lbs. See below for more.
• 24" 'hub-bar' will result in an 8'-4" rotor diameter.
• 36" 'hub-bar' will result in an 9'-4" rotor diameter.
• Can they be supplied in CW and CCW? Yes but see below.
• The hub will not be used. Perhaps do not purchase the hubs, or just purchase one to get the details on the parts
• Weight:
• Ultralight: 8 - 6 = 2 lbs for each blade. For 4 blades that is 8 lbs and for 6 blades it is 12 lbs
• The ultralight hub will therefore weigh 8 - (3 x 2) = 2 lbs, but we will be making a custom hub with a larger diameter.
• Medium: 14.2 - 11.2 = 3.0 lbs for each blade. For 4 blades that is 12.0.lbs and for 6 blades it is 18.0 lbs
• The medium hub will therefore weigh 14.2 - (3 x 3.0) = 5.2 lbs, but we will be making a custom hub with a larger diameter.
• Disk Area & Disk Loading:
• Ultralight: 72" dia. results in (36² x 22/7) / 144 = 28.29 sq-ft per rotor
• With 18" dia hub bar, 90" dia. results in (45² x 22/7) / 144 = 44.2 sq-ft per rotor.
• At a GW of 300 lbs the disk loading for 2 disks will be 3.39 lbs/ft²
• Medium: 74" dia. results in (37² x 22/7) / 144 = 29.88 sq-ft per rotor
• With 18" dia hub bar, 92" dia. results in (46² x 22/7) / 144 = 46.18 sq-ft per rotor
• At a GW of 300 lbs the disk loading for 2 disks will be 3.25 lbs/ft²
• Conclusion:
• The medium has a 14% lower disk loading than the Ultralight.
• For 2-blade rotors the increase in the gross weight is 3 - 2) x 4 blades = 4 lbs. 4 /300 = 1.33% increase in weight.
• Blade Area;
• From this picture it appears that the blade area of the Medium is 33% to 50% greater than that of the Ultralight.
• Go with the Ultealight or the Medium: ???
• Pictures:
• http://www.ultralightnews.ca/Ivoprop/images/ivohub.jpg
• http://www.ivoprop.com/images/3blade.jpg
• http://www.ivoprop.com/images/ivoehub.jpg
• http://www.ivoprop.com/images/newivoprops.jpg
• http://www.pfranc.com/projects/turbine/rotax/screws1.jpg
• Inside construction of blade; http://www.rotaryeng.net/Inside-the-IVO.jpg
• http://www.sdsefi.com/air18.html and more
• http://www.trikebuggy.com/products/propellers/ivoprop/pictures.htm
• October 2, 2009 ~ Ivo made the longer blades for Schoeffman. An employ sad that IVO is not producing custom blades anymore. He is making a vertical airplane in Utah. CORRECTION Franz said that the blades are stock Ultralight 74" blades.
• Is the extra 2' in diameter of any value, or is the chord significantly greater? Talk to IVO props?
• The rotors can be converted to 2 blades. "Easily and quickly converts from 3 blade into 2 blade configuration - giving you a spare blade."
• It is 20" over the motors and their mounts.
• Web links:
• http://www.tvbf.org/archives/velocity/msg00397.html

• http://www.rotaxparts.net/scripts/prodList.asp?idCategory=142
• http://www.rotaxparts.net/scripts/prodList.asp?idCategory=67
• Prop bolts M8-70.
• The Ivoprop comes with six (6) 8mm x 17mm bolts and fits the standard prop bolt pattern found on most paramotors, including the Compact Radial 313cc and the Corsair Black Devil 172cc.
• The large adjustment bolt is 1" OD with17 threads/inch.

Calculations: The following will have to be checked but could it mean that a large precone in the IVO blade would mean that most of the thrust from the blade would be coming from the root end, which is extended out due to the hub bar?

• For SloMo ~ Item 0070:
• Assuming: A 30" geometric pitch = 30"/Revolution
• An Effective Pitch of 70% = (30" x 70% = 21"/Revolution
• The required Induce velocity is 23.6 ft/sec
• This requires 23.6 / 1.75 = 13.5 RPS = 809 RPM
• For 600 RPM the geometric pitch should be (809/600) x 30 = 45"/revolution
• This results in an angle of attack at the blade elements that ranges from 2.62º to 4.52º
• The most desirable angle of attack is between 2ºand 4º. [Source ~ AP p.14]
• For MicroLite ~
• The induced velocity for hover with the Side-by-side configuration is 25.8 ft/sec from momentum theory. This involves a 3.883-ft [46.5"] radius, 3 blades per rotor, -14º twist, 0.333 ft [4"] chord, no taper, 0.2 cutout, and a blade pitch of 13.67º. The engine speed is 6,000 RPM with a 4.5:1 reduction. At 0.8 R the pitch is 3.87º and the angle of attack is 1.34º. The horsepower is 15.7 for both rotors at 300 lbs GW.
• The induced velocity for hover with the Side-by-side configuration is 25.8 ft/sec from momentum theory. This involves a 3.883-ft [46.5"] radius, 3 blades per rotor, -4º twist, 0.333 ft [4"] chord, no taper, 0.2 cutout, and a blade pitch of 6.32º. The engine speed is 6,000 RPM with a 4.5:1 reduction. At 0.8 R the pitch is 4.52º and the angle of attack is 1.68º. The horsepower is 16.3 for both rotors at 300 lbs GW.

• As an alternative the length of the hub bar is reduced down to 3" greater than the stock IVO hub 74"/2 " + 3" = 40", etc. The induced velocity for hover with the Side-by-side configuration is 30.1 ft/sec from momentum theory. This involves a 3.33-ft [40"] radius, 3 blades per rotor, -14º twist, 0.333 ft [4"] chord, no taper, 0.10 cutout, and a blade pitch of 17.6º. The engine speed is 6,000 RPM with a 5:1 reduction. At 0.8 R the pitch is 7.8º and the angle of attack is 3.46º. The horsepower is 18.6 for both rotors at 300 lbs GW.
• 75% of 40" is 30". The circumference is (30 * 2) * 22 / 7 = 189". At the minimum pitch range of IVO's Medium blades of 30" the pitch is 9º. This is a 'geometric pitch' [Source ~ AP p.14] of 9º
• On IVO's standard blade 0.75 R of 74/2" = 27". The circumference at 0.75 R (27 * 2) * 22 / 7 = 170" = 14.14'. At [6,000 RPM / 5:1 =] 1,200 RPM this gives 14.14 * 20 = 283 ft/sec
• At IVO's minimum pitch range of 30", 1,200 RRPM will result in 3000 ft/min, which is 50 fps. With slip of 15% the velocity will be 42.5 fps. [30 mph]

• Thoughts on Ultralight Propeller and Thrust:
• The Ultralight is good for up to 100hp.
• If this is three blades at 3,000 RPM then two blades at 1,000 RPM would be 100/(2/3)/(1/3) = 22.2 hp per rotor (propeller).
• Will this be a good enough blade at low induced velocities? Work with some of the propeller programs.
• What is the chord of the IVO propellers?
• What model of IVO propeller did Schoeffmann use?
• Is this F&P - IVO prototype going to tell me what is needed?
• The Medium blades only weigh 1lb each more then the Ultralight. I.e. 3 more lbs Go with them; at 74" diameter.

• Rotational speed: Setting the pitch (IVO)
• Jack Norris' Propeller book. Thread about the book; http://www.vansairforce.com/community/showthread.php?t=23721

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