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fred cenko

59 inch Bolly prop v 58inch IVO prop

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Took the new 59 inch fixed pitch bolly for a test flight today and compared it to the 58 inch ground adjustable IVO prop.The 2 improvements were a slightly better straight and level cruise speed with the Bolly

 

5150 Ivo prop was 5250.Much quicker response in power with the Bolly,especially with low level flights,no lag

 

in power as was with the IVO.The biggest let down was the climb rate,which was only 380 fpm full throttle at 6250IVO was 6350 and climb rate 400 fpm .the temp in the morning was 25 degrees as was the same with the

 

IVO prop,solo weight was the same me 88kg as was with the IVO. Tried to lean out the mixture as the plugs

 

were black, running rich,still could not get past 6250rpm.On a scale 1-10 I would give it a 5.Save your money and stick with the IVO

 

 

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Guest Andys@coffs

If the climb RPM was down then the engine isn't able to produce full power. Try reducing the pitch on the prop a little bit to see if you can get your climb RPM back to the point where the engine produces full power. Leaning the mixture will generally be a problem, full climb is usually by design rich, its the midrange rpms that you might well now have too lean.... I assume in saying this that the bolly prop is the adjustable pitch one...make sure both are exactly the same pitch.....I have in the past while adjusting these used a long laser pointer taped to the same place on the prop blade being adjusted (across the blade not along it, and across the bottom of the blade not the rounded top)) . before adjusting anything take the measurement of where the beam intersects the floor (will only happen on 1 side) and draw a triangle on paper representing the "as is" state. reduce the pitch angle by the desired amount on paper (1/2 to 1 degree at a time) and work out with basic trig on the paper now where the point should be on the ground..the point should move towards you( pitch reducing, or away pitch increasing) adjust on the plane to the new worked out position and then rotate the prop 180 degrees and set up the laser pointer in the same location on the other blade and adjust the pitch to the same point on the ground being sure that the pointer is located in the same place across the prop, same distance from the centre of the hub. (also note that cheap pointers may well move the point as you rotate the pointer (assuming a round cylinder) so its also important to have the point in the same location touching the blades.....

 

Or easier still get an electronic pitch guage which makes life much easier.....but probably not much more accurate....

 

I have also seen where people get a fine perm texta and mark the hub and the blade for each and then move the marks apart same amount for each blade...but that assumes the blades were exactly the same pitch before, if they were unbalanced then they still are, and in reducing the pitch you have made the imbalance as a percentage more significant.

 

Andy

 

 

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There is a cheap app. For iPhone or iPad which is an inclinometer accurate to 0.1 degrees. Put a marker tape on each blade, then with each blade level in turn, set the blade angle at the tape using the iPhone. Works perfectly for me. But I think the poor performer mentioned by Fred was a fixed-pitch Bolly, so no adjustment.

 

 

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Hi Fred,

 

as you know I have the 63" Bolly and previously the 59" Bolly. First thing you notice is that the Bolly's are a lot quieter than the Ivo with its square end. My findings are

 

Bolly 59" - I originally spoke to Peter at Bolly and he described the 59' as being less rigid down one side so the with increased RPM the pitch would be finer for climb out and at cruise with lower RPM the pitch became course. Downside I find when 2 up, higher revs required for straight and level as pitch would again become fine.

 

Bolly 63" - Extra expense due to Factory approved modification to airframe. Again a much quieter prop with low RPM cruise and good climb out.

 

Will be interesting to see results from the new wide blade 55" Bolly due out soon.

 

Info for those not aware of the Aerochute flight characteristics. The aircraft (32 rego Factory Built) is supplied with a 370 sqft rectangular parachute which has no trim. Due to limiting features the Aircraft cannot Stall or Spin. The level of drag is constant and the Airspeed cannot be changed (around 30knt) other that to add or remove weight hence the above discussions re RPM at S&L. you Take off, fly and land at the same speed, more power and you climb, less power and you decrease height, no power and glide is 4:1

 

 

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There is a cheap app. For iPhone or iPad which is an inclinometer accurate to 0.1 degrees. Put a marker tape on each blade, then with each blade level in turn, set the blade angle at the tape using the iPhone. Works perfectly for me. But I think the poor performer mentioned by Fred was a fixed-pitch Bolly, so no adjustment.

Would appreciate if you could let me know the name of that app.

 

 

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Hi Fred,as you know I have the 63" Bolly and previously the 59" Bolly. First thing you notice is that the Bolly's are a lot quieter than the Ivo with its square end. My findings are

 

Bolly 59" - I originally spoke to Peter at Bolly and he described the 59' as being less rigid down one side so the with increased RPM the pitch would be finer for climb out and at cruise with lower RPM the pitch became course. Downside I find when 2 up, higher revs required for straight and level as pitch would again become fine.

 

Bolly 63" - Extra expense due to Factory approved modification to airframe. Again a much quieter prop with low RPM cruise and good climb out.

 

Will be interesting to see results from the new wide blade 55" Bolly due out soon.

 

Info for those not aware of the Aerochute flight characteristics. The aircraft (32 rego Factory Built) is supplied with a 370 sqft rectangular parachute which has no trim. Due to limiting features the Aircraft cannot Stall or Spin. The level of drag is constant and the Airspeed cannot be changed (around 30knt) other that to add or remove weight hence the above discussions re RPM at S&L. you Take off, fly and land at the same speed, more power and you climb, less power and you decrease height, no power and glide is 4:1

Gday Mike

 

I will be taking up a 110kg fella next week with the new 59 inch Bolly,if we can get off the ground all will be vindicated with the Bolly as I know with the old ivo

 

there will be a chance of pruning the trees at the end of the runway.The Contes say the 55 inch Bolly will be out this month.

 

 

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Would appreciate if you could let me know the name of that app.

I phone 5 , go to the compas App and see the inclinometre on the other page

 

 

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Would appreciate if you could let me know the name of that app.

TiltMeter is a free app avail from the app store.

 

 

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When I changed from the 58 Ivo to the 59 Bolly I did a ground thrust test before and after changing. The Ivo was 100kg of thrust and the Bolly 110kg at full power. the Ivo was set to max revs in flight of 6500. The Bolly has no adjustment but got it pretty right, as max revs in flight are 6450.

 

The new 55 Bolly is available now direct from Bolly. There is one in WA already. It however is only suitable for the 582 Hummerchute i believe.

 

Kev

 

 

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The owner of the new 55's hasnt put them on yet but i have asked him to do some trust tests on his current 63 prop and again when he replaces with the 55's. If i get the results i will post them. They are the weirdest things i've seen, looking more like a Pizza turning paddle than a prop!!

 

Kev

 

 

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