Stepping up to old 680V turbine...

[donv]

The windows do look really good. Does the 680V have alcohol windshield deice?

[Adam Frisch]

Yes they do, Don. So they're lot cheaper than the heated ones on the 690-series. But probably scratch easier.

[donv]

I wonder if they fog up at altitude?

In the 690s and JetProps, you turn the windshield heat on "low" climbing through FL180, or they will fog over completely.

I flew a straight 690 with the heat on the left side only, but that's my only experience with non-heated windshields in Commanders. I don't remember if the straight 690 fogged up or not... it probably did.

[Adam Frisch]

The main thing that will be limiting on the 680V, is probably the 4.2psi cabin diff and the fact that the wing and Century engines run out of poop around FL220. These, and the 681's, are high teens to low 20's planes. Now, you can get them up to the service ceiling at FL250, but your cabin will be almost at the legal limit, which is tiring. Also, living here in California, I'm not experienced enough in hard IFR to know if FL200+ normally gets you on top. In my experience from California, yes, but that's probably not true for the rest of the country. And that's what I intend to use it for - travel - so I'm sure I'll eventually find out. Being in the soup I don't have a problem with for a little while, but it gets tiring on long trips. Not to mention icing only happens with visible moisture.

[donv]

I think you'll be fine most of the time. One nice thing about being up in the 20s is that you generally don't get much ice (I still run the nacelle heat), because it's too cold. That's not to say you won't get some, but it doesn't accumulate like it does down low.

The one place where you can get quite a bit is right in the tops of the clouds.

[Adam Frisch]

Thanks Don.

What's you're experience with TC's in ice? I've heard they're pretty solid ice carriers.

[SKYFLYER]

Not so much about ice on the TC but landing on... http://forum.keypublishing.com/showthread.php?56538-Does-anyone-have-information-on-Aero-Commanders-using-Skis-on-snow-Ice
While I try to avoid any icing conditions.. I have never found the icing limit for the aircraft or myself..... As long as the equipment is operable and you remember to turn it on...
There was a story awhile back about the NOAA commander suddenly taking on copious amounts of clear ice (super cooled droplets) that was reported to have all but encased the aircraft and they were not sure how much the ice weighed, but got thru it.
I would prefer to never have that happen.

[donv]

I've never felt uncomfortable due to ice accumulation (as long as the nacelle heat was working)... However, as a west coast guy, most of my flying has involved climbing up through it, or descending through it. If I was slogging between Teterboro and Boston at 12,000 feet every day, I might feel differently...

I have seen some pretty good ice accumulation, though, and it was never an issue. At the altitudes where you can get a lot of ice, any Turbo Commander has plenty of power.

One thing you should keep in mind is that the nacelle heat valves can stick if they aren't used occasionally. In the summer, I will often cycle mine when descending through FL180 to keep them exercised.

[Adam Frisch]

When you say nacelle heat, you mean the smile, right? The inlet.

[donv]

Yes, the inlet heat.

[EricDapp]

So if a 680V has been upgraded to MU-2 engines what would they be? Would that change make them a good performer?

What other issues would there be? Pressurization?

[Adam Frisch]

There are only 2 conversions possible as far as I know. The -1 Century conversion I have, which makes it almost identical to a 681, or the rather rare "Super Dave" conversion that mates a -6 compression section to the 1-turbine stage. This last conversion makes them real performers, but there are only a few in the world. There is actually a 681 for sale with this conversion in Canada now. Could be a good deal for the right buyer.

None of the conversions improve the pressure differential, so you're still stuck with the 4.25psi. Also, in combination with the shorter wings of the 680V/681 family, these are not best suited for the highest FL's. They're best in the high teens, low levels.

[donv]

The MU-2 and Commanders of similar vintages used basically the same engines, except the MU-2 engines are mounted upside down. So I don't think there is any advantage to the engines used by the MU-2.

[donv]

Any updates on your 680, Adam?

I'm headed to Bermuda Dunes tomorrow...

[Adam Frisch]

Wish I could meet you there in my steed, but alas, things are much the same as they were. We're getting there, but end of Jan perhaps. I've stopped counting the days.