REFLECTOR: From IVO

Mon Jun 28 08:00:29 CDT 2004

Hey Brian,

I had called IVO and spoke with him about the prop.  As you had said,
the problem is with the power pulses.

What I had surmised was that he twists the blades to achieve his
constant speed like functionality.  To do this he needs to keep the
blades flexible enough to twist.  If he added more beef to the blade, he
could take more power and stronger pulses.  The prop would also be
stiffer and would not be able to twist.    I don't know that his product
would have any real advantages if it were fixed pitch.

I did ask about beefing up the blade and accepting a limited twist.  He
said that with 200 hp you will need all the twist the blade can produce
now.  He didn't think it would be helpful.

He has thought about adding some type of shock absorber or even a type
of torque converter to even out the power.  He could afford the weight,
but felt the heat generated by such a device would have all kinds of new
problems.

Andy

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brian Michalk
Sent: Sunday, June 27, 2004 9:32 PM
To: Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: From IVO 

How about some truth in reporting?

A minor nitpick, their website says 700 horsepower, not 720. Now, I
would be very cautious about this claim, because we all know about the
history of the IVO.  However, suppose that IVO prop were mounted on a
turbine engine?  Would it take 700 horspower?  Perhaps.  Someone should
ask IVO for the engineering data on this application ... a responsible
thing every builder should do.  It appears as though you were one of the
responsible builders.  You asked if their product could be used on a
TSIO520 in pusher configuration, and the response was "no".

It looks like the TSIO520 is good for 310(285 from other sources)
horsepower at 2700 RPM.  The MTV-18V electric prop weighs 45lbs and can
take a max 260HP at 2800RPM.  It's not big enough for your engine. The
MTV-23 prop weighs 55lbs, and can take 350HP at 2700 RPM.

I could not find any information on the MT regarding specific operating
limitations, although it does address them, it does not say which
engines are affected.  Likewise, the IVO site does not say which engines
have operating limitations with their prop.  As a side note, I did find
this
interesting: http://www.mt-propeller.com/pdf/manuals/e-118.pdf.  For
overspeed limitations their chart for piston engines start at 110% RPM
whereas the turbine engine graph starts at 120% max RPM.  So even MT
acknowleges a difference in engines.  The point I'm getting to is that
it's about power pulses and resonant vibrations being the problem, not
Maximum absolute horsepower.

The IVO weighs in at 26.7 lbs.  Almost half of the MTV-18.  Beef up the
IVO until it weighed similar to the MT, and it *may* perform equally.
But it doesn't weigh as much, so it most likely compromises on
structural integrity at the higher torsional forces.

I feel that the MT has real engineering, and real test cell data behind
it. I saw a WWI documentary, and saw some footage from a factory and
swore the logo on the props were identical to the MT logo, but their
site says they have been in business since 1981.  I also can't help
noting that they like to blow their own horn as well with the following:
"mt-propeller Entwicklung GmbH is specialized in the development, design
and manufacture of variable and fixed pitch propellers for engines
producing up to 4500 hp."  Now, I'd like to see a piston engine at
4500HP not break a few propellers before they get it right.

The 700HP IVO, and the 4500HP MT are most likely maximum engineering
limits, and not flying examples.  I have no information either way.

So, I'll get off my soapbox about here and say that starting a flamewar
over XXX product is rediculous.  I've seen the performance of IVO, and
MT on two Velocities.  Both Franklin, both retract, only difference is
one is a 173. Both props have performed up to now flawlessly.  Would I
like an MT?  You bet.  Would I pay for one?  No.  I would pay $5,000 for
one.  That's what I think it's worth.  I'll go with the IVO, because
I've seen it work on similar installations, and IVO blesses this
combination.  In parting, one last quote from the MT site(
http://www.mt-propeller.com/pdf/manuals/e-118.pdf ):

People who fly should recognize that various types of risks are
involved; and they should take all precautions to minimize them, since
they can not be eliminated entirely. The propeller is a vital component
of the aircraft. ... It is essential that the propeller is always
properly maintained according to the recommended service procedures and
that a close watch is exercised to detect impending problems before they
become serious. Any grease or oil leakage, unusual vibration, or unusual
behavior during operation should be investigated and repaired as it
could be a warning that something serious is wrong. Gerd R. Muhlbauer
President MT-Propeller Entwicklung GmbH

This holds true for any equipment on our aircraft.
Okay, flame away.

 Brian Michalk  <http://www.michalk.com>
Life is what you make of it ... never wish you had done something.
Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
musician, home-brewer, entrepreneur and barely single

> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Scott Derrick
> Sent: Sunday, June 27, 2004 8:43 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: REFLECTOR: From IVO
>
>
> I sent IVO a request about their claim on their website that they made

> props for up to 720 HP.  Here's  their response.
>
> Sounds like they can't handle anything but the weenie ultra light 
> motors to me.
>
>
> Dear Sir,
> We will not be putting anymore Ivoprops on Lycoming powered aircraft. 
> nor Cadillac direct drive, Continental O360, O470, O520, 0540, 
> DeltaHawk, Jabiru 8 cylinder, Limbach, LOM, and M14P engines due to 
> pulses and harmonics. Regards, www.ivoprop.com
>
>  >From: "Scott Derrick" <scott at tnstaafl.net>
>  >To: <ivoprop at pacbell.net>
>  >Sent: Saturday, June 26, 2004 1:15 PM
>  >Subject: TSIO520
>  >
>  >
>  >> Do you have a prop that would work on a TSIO520, in a pusher  
> >configuration.  >>
>  >> thanks,
>  >>
>  >> Scott
>  >>
>
> "Those who sacrifice freedom to get security, deserve neither."
> - Benjamin Franklin
>
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