1814

Item 1814

BUY: PropRotor - for MicroLite - IVO - Medium

Notes:

IVO:

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
2-blade. 6 lb. $440.00
3-blade. 8 lb. $600.00
24" 'hub-bar' will result in an 8 ft rotor diameter.
36" 'hub-bar' will result in an 9 ft rotor diameter.
3 blades should significantly reduce the vibration when the rotor head is subject to pilots

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
24" 'hub-bar' will result in an 8'-2" rotor diameter.
36" 'hub-bar' will result in an 9'-2" rotor diameter.
Thought: This has a lower minimum pitch than the Ultralight. This may be better for the slower induced velocity of a rotor when compared to that of a propeller.

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
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 (36²x 22/7) / 144 = 28.29 sq-ft per rotor

With 18" dia hub bar, 90" dia. results in (45²x 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 (37²x 22/7) / 144 = 29.88 sq-ft per rotor

With 18" dia hub bar, 92" dia. results in (46²x 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 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

Inside construction of blade; http://www.rotaryeng.net/Inside-the-IVO.jpg

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.

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

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?

The most desirable angle of attack is between 2ºand 4º. [Source ~ AP p.14]

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]

Additional Information:

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

Last Revised: December 21, 2009