Mike,
Like many builders of experimental aircraft, when it came to prop selection I was not sure what size prop I needed for my application.
I have a Dyke Delta and I'm using an Atkins build Mazda 13B 6 port NA engine.
It came with a Ross 2.85:1 PSRU.
After looking up and down the flightline at Oshkosh I saw that many of the experimental
aircraft were using an IVO prop so I called IVO to see if they had a prop to fit my application.
After discussing the parameters of my application they recommended the IVO Magnum 3 blade 72"dia 45-105" pitch.
As for performance data I don't have too much to offer as I have only flown 4 hours so far.
I set the prop for a mid pitch setting (about 70-75") which keeps the engine from over
revving and still gives a decent cruise speed of about 140MPH at 75% power setting of about 5400RPM.
This was with the landing gear down so I'm sure that when the gear is up and the prop is set for more pitch the cruise will increase to 170-180MPH (typical for this airframe w/0-360Lyc).
The climb rate at this pitch setting was about 1500 FPM at 120MPH.
When I get more performance data I will be happy to post it.
The limiting factor on the RV's seems to be the length of prop that is used.
I think that Vans was recommending a 68" dia (probably for clearance reasons) which was based on the Lyc engine.
When using a 68" IVO prop with the rotary and 2.17:1 the performance is less than spectacular.
One of our Delta builders tried this combination and was not happy with the performance.
He switched to the warp drive with better results.
So if you have room to use a longer prop the IVO may be a good choice but if you are limited to 68" then it is probably not recommended,
For more info on all be various combinations available for IVO props see:
I hope that I answered your questions.
If there is more specific info that you need please feel free to contact me.
Jim
--- On Mon, 3/16/09, Mike Wills <rv-4mike@cox.net> wrote:
From: Mike Wills <rv-4mike@cox.net>
Subject: [FlyRotary] Re: IVO Prop
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Monday, March 16, 2009, 8:58 PM
Jim,
So can you describe your specific application? Engine, prop, ratio, airframe, and some performance data?
In my case I have the 2.17 ratio - when I bought it there was no 2.85 option. This is in an RV-4 with a second gen 13B built by Bruce Turrentine with high compression NA rotors and turbo rotor housings.
I always kind of assumed that with variable pitch, prop selection was considerably more forgiving. Did not realize there were so many options for the IVO (actually I dont think there were so many when I was looking before).
Mike
Mike
----- Original Message -----
Sent: Sunday, March 15, 2009 12:05 PM
Subject: [FlyRotary] Re: IVO Prop
|
I have been reading with much interest the discussion about IVO props lately and felt
that as a, so far, happy owner of one that I should chime in.
When determining the success or failure of the IVO prop it is much the same as determining the success or failure of the rotary engine.
The IVO prop like the rotary engine is not a single entity.
There are many different sizes and possible configurations of both a rotary engine and
the IVO prop.
When you combine the two then the combinations become staggering.
The "IVO prop" has at least 3 different blade profiles, the blades can be configured from 2 to 6 blades in a hub determined by the amount of HP you wish to absorb, the length of the blades and their pitch adjustment are also factors.
Finding the proper combination will ultimately determine the success or failure of the "system".
The correct combination must also be determined based upon the application.
An example of this is in the early years of matching the rotary to the prop was that the
conventional wisdom of the time was to use the 2.17:1 PRSU and a short prop turning at
high revs.
Some tried this using the IVO prop and it did not perform as well as some other props in this situation.
I think that it has been discovered over time that a better combination for the IVO in
higher performance aircraft is a longer blade with higher pitch turning slower gives better
efficiency.
So it is not so much whether the IVO has succeeded or failed but more like do you have
the correct combination of engine, PSRU, and prop configuration for the application you
are intending it to operate in.
Just my opinion of course. YMMV
Jim
--- On Wed, 3/11/09, Mike Wills <rv-4mike@cox.net> wrote:
From: Mike Wills <rv-4mike@cox.net>
Subject: [FlyRotary] Re: IVO Prop
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Wednesday, March 11, 2009, 10:02 PM
John,
I looked pretty seriously at the IVO a number of years ago. But was scared off
by a number of things:
1) Watched Dave Atkins repairing a delaminated trailing edge on the flight line
at Copperstate fly-in.
2) A friend with a Kolb Firestar/Rotax 503/ground adjustable IVO had the prop
come apart in flight resulting in a forced landing that totaled the plane.
3) Tracy's experience re reduced performance at speed.
4) The issues experienced by Lyc powered users.
Numbers 1 & 2 were possibly due to something going through the prop with
the engine running. Issue 4 seems to be not relevant. This leaves Tracy's
experience with the IVO. I wasnt thinking about the fact that you fly a pusher
when I asked, but presumably a pusher would not have the prop root issue that
Tracy reported. On my RV-4 I use a much larger than stock spinner and this issue
may not be as significant as it was for Tracy. But I'm not sure I want to
buy one to find out. My current prop seems to be pretty close though I havent
flown it enough to really make a judgement.
Thanks for the feedback.
Mike Wills
RV-4 N144MW
----- Original Message ----- From: "John Slade"
<sladerj@sbcglobal.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, March 10, 2009 9:41 PM
Subject: [FlyRotary] IVO Prop
> >I didn't know anyone had ever had any success with an IVO. Tell me
more.
> What do you want to know? Its a very well engineered piece of equipment.
The CF blades are hollow and have a steel rod running to the hub. Activating the
motor via brushes twists the steel and thus twists the blades equally. The twist
change is quite visible. There were problems with the individual blades slipping
on the hub. This has been solved by providing a knurled hub, and not selling to
guys with Lycomings. The IVO is available for rotary, subaru, Franklin 6 and
other less "pulsy" engines. After the first 15 hours or so my blades
have hardly taken any extra torque.
>
> My performance is greatly enhanced compared to the fixed pitch Performance
prop. Static with the wood prop was around 4500. With the IVO on full fine I get
closer to 5400 which gives me access to a lot more power on take off. I've
never done a "high speed" run with the IVO, but I've had 180 kts
indicated at 2000' a few times without much effort, and without ever going
to the full course setting. Another nice bonus is that throttled back on full
fine for landing, the prop acts like a brake. Its much easier to land and stop
than the fixed pitch that's pushing you along fairly well, even at idle.
>
> I know a Velocity driver (Mike Watson) who also uses an IVO (Franklin 6)
and is very happy with it after around 5 years of use.
>
> The factory people are very easy to deal with and very helpful.
>
> The Cozy Girrrls are installing an IVO. What better recommendation could
you want? :)
>
> Regards,
> John Slade
> Turbo Rotary Cozy IV, N96PM
> 98.1 Hrs.
>
> Mike Wills wrote:
>>
>>
>> Mike Wills
>> RV-4 N144MW
>>
>> ----- Original Message ----- From: "John Slade"
<sladerj@sbcglobal.net>
>> To: "Rotary motors in aircraft"
<flyrotary@lancaironline.net>
>> Sent: Tuesday, March 10, 2009 10:30 AM
>> Subject: [FlyRotary] Re: Ground Testing
>>
>>
>>> The IVO electric in-flight adjustable costs around $2350. I'm
very pleased with mine. My "spare" is a $2700 fixed pitch wood prop
thats a piece of art, but doesn't work anywhere near as well.
>>> John
>>>
>>> Tracy Crook wrote:
>>> A variable pitch prop would be nice to get the best of both worlds
but it's an expensive option and $10,000 buys a lot of gas.
>>>
>>>
>>>
>>> -- Homepage: http://www.flyrotary.com/
>>> Archive and UnSub:
http://mail.lancaironline.net:81/lists/flyrotary/List.html
>>>
>>
>>
>>
>> -- Homepage: http://www.flyrotary.com/
>> Archive and UnSub:
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>>
>
>
> --
> Homepage: http://www.flyrotary.com/
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>
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