lml@lancaironline.net Mailing List Archive

Hi Mike

The BETA in flight are prohibited with 2 safety features, the first is an airspeed switch (so your plane needs to go less than 70knots, the second is RPM limited (<1200rpm).

A loss of oil pressure will turn your blades into feather, not beta.

The plane itself when switching to Beta on low RPM is doing nothing that will make you wondering what it will do next (I did Beta on a p210 with Allison conversion (Silver Eagle) and this had a much bigger effect on the plane than this one does.

So when I was going into Beta the tail already is about doing nothing anymore (speed is below 70kts, actually 66kts), so the tail effect was not noticeable at all. The plane was steering the same or even better now just using the brakes, which you now use less.

About the delamination, this will have to show over time, I cannot comment on this as I do not have this experience.

But thanks for the tips, and yes the blades are ALWAYS on my preflight check….and now even more J

== Ronald

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Mike Larkin
Sent: Friday, October 18, 2013 10:33 AM
To: lml@lancaironline.net
Subject: [LML] Re: MT prop fully reversible 1st report...

Ronald,

I have spent many years flying a large variety of airplanes with reversible pitch props, both certified and experimental. Things to think about: Can YOUR airplane going into Beta in-flight? Do you have enough redundancy in the systems to prevent this. Second, blade flex! Low RPM reverse is very stressful on the prop blades and MT's are not very tolerant of this. You won't have to deal with a failure, but blade de-lamination is greatly accelerated vs time. Lastly, loss of tail effectiveness (rudder) at high power reverse which reduces and/or eliminates directional control with the rudder on deceleration. This can create problems on contaminated and narrow runways. The 4p Turbine suffers from this but is controllable. Food for thought!

Mike Larkin

4LL ect...

On Fri, Oct 18, 2013 at 4:55 AM, Ronald Stevens <ronald@sdc.com> wrote:

Hello guys

As I told many months ago, I planned to get the 4 bladed MT prop fully reversible and fully feathered. Today it came finally together….

The reason it took so long is that it took some adaptions on the plane, a confused wire plan and off course the delay just getting the prop and the governor.

Today I had my first experiences and will report more once I can test it without any wind conditions to see how it really performs, but so far it did really well. The system has 2 switches, where 1 is to ‘arm’ the system, and the other to use it as the ‘beta’ switch.

Now my first fast taxi was very uneventful, as a matter of fact, I was kind of disappointed not seeing a huge effect right away. I taxied at about 30 knots and switched it on and ….almost nothing happened. This actually is a good thing (I found out later), as the system is actually very smooth going into beta without any ‘wiggling’ or any unease feeling of a plane suddenly going another way.

My first faster taxi (at 60 knots) was at least more eventful, when I switched it on, and had the prop was at about 700rpm, I just noticed that it had a little extra drag, but than giving it some throttle it started to give some nice braking action. But all very comfortable, nothing weird, just simple.

So I took it into the air, and landed with the system, and for sure with some good practice I can land the plane between 1500-1800ft. (going with 90knots over the numbers, today I was already within 2000ft). This is great when the gremlins are taking away some runway in the night going in to hot J

The system does have some safety features like it cannot go to reverse above 70knots or when the prop is higher as 1200rpm. The feather works the same as with the Hartzell (just pull the prop).

So far it was working fine, and when I have some more experiences with it (not doing crazy stuff) I can provide some real numbers of how much runway not it takes to land the 4p with this combination. I will not go extreme with going full throttle once activated, throwing is dust and dirt all over the plane LOL

The prop and installation is not cheap, but running of the runway is more expensive J

The installation was done by Matthew Collier from Fibercraft and Avionics Instalations, here in Spruce Creek, Florida (7FL6).

Ronald Stevens (400h LNC4p and some….) n45HL

--
Mike Larkin
LarkinAviationConsulting
LegacyL2K@gmail.com
602-770-6054