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  #16  
Old 08-11-2005, 09:55 PM
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rv6ejguy rv6ejguy is offline
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IVO went to the knurled clamping plates in 1998-99 I think and issued a specific procedure for torquing and checking the bolts, plus issued stainless tape to apply to the blade junctions as a visual indication of loose blades. Since these improvements, I am not aware of any problems with walking blades on non-aircraft engine applications where THE PROCEDURE HAS BEEN FOLLOWED PROPERLY.

Most initial problems seemed to be with cert type engines with strong power pulses. The original smooth clamping plates were certainly not a good idea, no doubt about it.

I do remember reading something about a pusher application where the blades disintegrated and pieces were still hot to the touch after the aircraft landed. Theory was that the blades were flexing at high frequency as they passed the wing wakes on each revolution. My recollection may be fuzzy on this one.

Because of the blade flexibility of the IVO, I notice in turbulence that a certain low frequency vibration is sometimes set up. I notice the same thing on the ground when taxiing with a strong, gusting tail wind...?

I was cautious about the IVO when I was prop shopping initially as there were some unflattering stories. A few people did have bad experiences years ago. Obviously having props fall apart makes you mad and scares the crap out of you if you survive, so the bad stories made their way around the net rapidly. Looks like IVO has things fixed and they have been an excellent company to deal with. They still don't want to see their props on Lyc, Conts or Franklins.

Just isn't much else out there for engines over 160hp or so, anywhere close to the IVOs price. NSI has had some serious issues with some of their CAP series props. The RAA in Canada has been pushing for them to issue an AD on one type which has had multiple blade/ hub failures, without success. NSI does not have the best reputation for customer support to put things mildly however I understand just in the last few days that their engine/ propulsion division is under new management. They apparently fired almost everyone and hired back a selected few to start over and clean up their act. Hopefully things will change there.

Everything else out there is either deadly heavy like Hartzell and/or deadly expensive like Whirlwind, MT etc.
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  #17  
Old 08-11-2005, 11:40 PM
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Quote:
They still don't want to see their props on Lyc, Conts or Franklins.
The Velocity coming to our hangar has a Franklin. I spoke to IVO today. They said the rotary is fine, and the 6 cyl Franklin. The in-flight 3 blade 68" adjustable magnum prop is $2170. They have a constant speed option for another $300. Anyone have any experience with it. Is it worth the extra $ ?
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  #18  
Old 08-12-2005, 12:56 AM
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Quote:
Originally Posted by Dust
Although the sample is tiny - one hydraulic and he is unhappy with very high maintenance costs, it is probably valid to assume that it is true - any one have any other experience with MT
I'd like to see a qualification of expensive... Constant speed prop overhauls are not cheap, infact you could easily buy one, if not two Catto or even IVO Magnums for the price of an overhaul on a certified constant speed prop.

Quote:
Originally Posted by rv6ejguy
Many helicopter rotors have no conventional hinges and flex the composite blades. Seems to work.
Helicopters scare me from the beginning. They are the bullies of the aviation world. Planes ask semi-nicely to be in the air, helicopters just beat the air until they get their way.
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  #19  
Old 08-12-2005, 03:04 AM
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Quote:
Originally Posted by John Slade
The Velocity coming to our hangar has a Franklin. I spoke to IVO today. They said the rotary is fine, and the 6 cyl Franklin. The in-flight 3 blade 68" adjustable magnum prop is $2170. They have a constant speed option for another $300. Anyone have any experience with it. Is it worth the extra $ ?
John... especially in your setup, an adjustable pitch prop should be worth it. In your situation, you can set the rpm to be the best torque (or best rpm) for your engine... and control the POWER with increased manifold pressure.

You may not see ANY improvement on the top end at all.. IF your current fixed pitch prop was optimized to your HP and airspeed in cruise. Where you will see the benefit will be in improved climbs, the ability to make steeper descents and better low power responsiveness and operations.

Based on Tracy's and other's comments about the IVO I had found myself fairly "anti-IVO" but I have come across at least one or two pushers who HAVE the IVO who have had acceptable performance with the IVO (top end speed wasnt penalized - the IVO has a "flat" area near the hub that may have contributed to this penalty in tractor planes)

I am now pretty much open to the IVO, and hopefully Chris and I will be placing one on the Velocity.

Dave
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  #20  
Old 08-12-2005, 07:57 AM
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Quote:
You may not see ANY improvement on the top end at all.. IF your current fixed pitch prop was optimized to your HP and airspeed in cruise. Where you will see the benefit will be in improved climbs, the ability to make steeper descents and better low power responsiveness and operations.
BINGO

My MT is 5 knots slower than my fixed pitch. I think you'll find this true with most (all) constant speed props. If you look ONLY at top end speed, then your best performing option just happens to be the least expensive (maybe) option.


Now for the "Rest of the Story":

What will the fixed pitch speed be if its only turning 2300 rpm?
MT Prop - I cruise at 167kts @ 2300rpm (full throttle)
Fixed - (approx 120 kts) I cruise at 170 kts @ 2900rpm (full Throttle).

What is the takeoff roll distance for a 1800 lb LongEZ?
MT Prop - 700 ft
Fixed - 3500 ft

What is the rate of climb at best rate (90 kts) at 1800 lbs?
MT Prop - 1400 fpm
Fixed - 300 fpm


Waiter
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  #21  
Old 08-12-2005, 10:26 AM
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Quote:
Originally Posted by Waiter
What will the fixed pitch speed be if its only turning 2300 rpm?
MT Prop - I cruise at 167kts @ 2300rpm (full throttle)
Fixed - (approx 120 kts) I cruise at 170 kts @ 2900rpm (full Throttle).
What's the difference in fuel consumption?
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  #22  
Old 08-12-2005, 11:34 AM
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karoliina karoliina is offline
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Quote:
Originally Posted by Waiter
What is the takeoff roll distance for a 1800 lb LongEZ?
MT Prop - 700 ft
Fixed - 3500 ft
What is the rate of climb at best rate (90 kts) at 1800 lbs?
MT Prop - 1400 fpm
Fixed - 300 fpm
That is a good reason enough to have a in flight adjustable propeller.
Using fixed pitch prop would force using only the biggest airfields
and would reduce the usability of the plane. There are some nice
places in Lappaland of Finland that have no longer than 2100 ft runways (still quite ok quality asphalt, but very short and narrow runway).
I know it is a bit challenging to operate a Cozy from a such short field, but
still there are certain places that worth visiting and would be otherwise unreachable. Even on fast plane, the low end is very important too. I used to think that the climb rate is not so important as long as the plane cruises fast, but I already once had quite hard time getting our plane up from the ground before the end of the runway was reached (I had already gone further than the point I could have cancelled the take-off) that I am feeling that I want to experience that never again (it was quite scary I must say - few liters more gasoline in tanks, a second or two more before it would have gotten up to the groun effect
and I would have totalled the plane...)...

In order to be able to use them, it seems that a in-flight adjustable
prop is a must or otherwise a severe compromise needs to be done
at the top end. We have ground adjustable prop in our non-canard plane and we have been optimizing the angle backwards and forwards. Now it is at a compromise that we can safely take off from the short airfields - we have
sacrificed from the top end some 20-30 km/h because of that (and it is a huge difference on a slow plane like ours). Still our plane could preferably get faster off the ground, our flight club's WT9 Dynamic with the in-flight adjustable prop starts up like a rocket in comparison.
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  #23  
Old 08-12-2005, 11:43 AM
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Quite a few cozy o360 fixed pitch prop planes operate out of 2000 foot runways. i am guessing that waiter has a cruise and not a cruise/climb prop

i was in Nats plane and we climbed at 1200 FPM and had 207 IAS at 6000 on a 100 degree day in mesa, AZ
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  #24  
Old 08-12-2005, 12:01 PM
Wayne Hicks Wayne Hicks is offline
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O-360s, fixed pitch prop, off 2,000 foot runways? Who might that be?

Lightly loaded, I can believe launching from 2k rwys. I'm assuming good brakes as these plane usually need the same if not more stopping distance than to take off.
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  #25  
Old 08-12-2005, 12:05 PM
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Dust... what kind of take off and climb performance will you get with a fixed prop optimized for cruise at 25,000 feet?
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  #26  
Old 08-12-2005, 12:25 PM
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Quote:
Originally Posted by Wayne Hicks
O-360s, fixed pitch prop, off 2,000 foot runways? Who might that be?

Lightly loaded, I can believe launching from 2k rwys. I'm assuming good brakes as these plane usually need the same if not more stopping distance than to take off.
Not used for flight testing. I would have to read the back issues from nat as i remember him mentioning some one who lived on a 2000 runway and freely came and went, after he was totally familiar with the plane
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  #27  
Old 08-12-2005, 01:07 PM
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My knuckles would be white operating this fixed pitch combo from a 2000 foot strip on a hot day with no wind. No thanks. If I left my IVO in cruise pitch and attempted a takeoff, I'd count on at least 5 times the distance to break ground.

I've said it before. An atmo auto engine with a fixed pitch prop is a dog in the climb and takeoff modes. With a turbo, it may be acceptable. I guy I gave a ride to in my -6A turbo IVO who was used to his Lyc fixed pitch Sensenich O-360 remarked "Holly S**T, does this thing accelerate compared to mine." He couln't believe the climb angle either. After he said he should never have taken a ride as he was pretty happy with his airplane before this experience spoiled him for life.

Waiter's figures pretty much tell the same story I see.
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  #28  
Old 08-12-2005, 01:46 PM
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Quote:
Originally Posted by rv6ejguy
An atmo auto engine
yeah, but we are not talkin about an auto conversion, we are talkin about a plane airplane engine
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  #29  
Old 08-12-2005, 01:57 PM
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Don't get me wrong, I am green with envy over Waiters performance numbers and just to mention it, his retract project but.............

$10,000 for the MT prop etc. buys a lot of trade offs.

Nose wheel retract
New GPS,
Tons of gas, well maybe not tons with prices now
The major part of a complete engine overhall
Maybe some main gear retracts
My engine and $10,000 gets me a zero time O-320 factory done

These other possibilities either alone or in combination might be worth the
sacrifices.
On the other hand if $50,000 fell into my lap I wjsu might do all of the above including the prop.

Just trying to inject some normalcy into the world of us dreamers
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  #30  
Old 08-12-2005, 02:34 PM
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Quote:
Originally Posted by Dust
yeah, but we are not talkin about an auto conversion, we are talkin about a plane airplane engine
Yes, that's why I qualified this statement. A Cont or Lyc is a totally different story as the torque and power peak rpms are within a few hundred rpm rather than a few thousand as in most auto conversions. The cert type engines can have adequate takeoff and climb performance with a FP prop as you said.

You have serious problems with FP props on any type of turbocharged engine at high altitude. To get any sort of decent compromise for SL takeoff, climb and cruise at 10,000 and at 25,000 is almost impossible. I'm not aware of many (any) turbo cert engines fitted with FP props.

I run out of coarse pitch adjustment on my IVO at about 12,000 feet and 30 inches. The higher you fly, the more pitch you need.
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