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Author Topic: 980 Questions  (Read 10256 times)

JMA

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980 Questions
« on: February 19, 2018, 01:21:32 pm »
Question-I will ask Bruce/Don- why on the 690 series then again on the 695A/B did you have a the leading edge added for the tail (as below, I believe they call it the dorsal fin), but yet the 980 did not?

Adam Frisch

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Re: 980 Questions
« Reply #1 on: February 19, 2018, 01:29:35 pm »
Good question!

The easiest way to spot an 840 or a 980 is the lack of dorsal fin. In the beginning I thought they looked "naked" without them, but now I actually think they look best this way. The 690A/B fin is very easy to spot as it has a a straight incline. The ugliest fin is the one on the 900/1000 model, in my opinion. It's got a weird curve to it.

Slumming it in the turboprop world - so you don't have to.

JMA

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Re: 980 Questions
« Reply #2 on: February 19, 2018, 02:04:36 pm »
I agree, I think its a 'cleaner' look.

The 1000 does seem an odd angle, but then again, N51DM is 1000 with no dorsal?



donv

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Re: 980 Questions
« Reply #3 on: February 19, 2018, 02:27:50 pm »
Great question, and I don't know the answer. I'm sure that there was some reason for it... but you'd think the 980 would need it and the 840 wouldn't, not the other way around. It can't make that much of a difference.

It seems to cause corrosion problems:

http://twincommander.com/wp-content/uploads/2015/12/Maintenance-Alert-TCA-Dorsal-fin-Service-Alert.pdf

Twin Commander has come out with a couple of replacement fins, etc as custom kits.

Bruce Byerly

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Re: 980 Questions
« Reply #4 on: February 22, 2018, 07:26:01 am »
I think the engineers finally beat back the marketing department and got back to closer to perfect - like a 500 model  ;D

The big fairings look cool but just cost money, and may trap moisture which leads to nothing good  when combined with steel fasteners.

JMA

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Re: 980 Questions
« Reply #5 on: February 26, 2018, 08:47:11 am »
Sorry not necessarily a 980 question...

On the -5, you would see a full exhaust, sometimes full metal, sometimes painted white...
How come I have seen some -5 with the exhaust cut diagonally like the -10... is there is a difference, why the change?

Not sure if that question is asked correctly, but hope it makes sense.

donv

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Re: 980 Questions
« Reply #6 on: February 26, 2018, 11:29:08 am »
I think it makes it look iike a -10...

JMA

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Re: 980 Questions
« Reply #7 on: February 26, 2018, 12:48:01 pm »
Ah, just trying to look more powerful... got it...

Mike Floyd

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Re: 980 Questions
« Reply #8 on: March 07, 2018, 12:22:03 am »
I think it makes it look iike a -10...
CK161 – Exhaust Duct Mod - $13,412.73ea

donv

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Re: 980 Questions
« Reply #9 on: March 10, 2018, 12:50:48 am »
The other one is the "stinger" tail on some 690As...

Bruce Byerly

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Re: 980 Questions
« Reply #10 on: March 13, 2018, 06:50:34 pm »
Sorry not necessarily a 980 question...

On the -5, you would see a full exhaust, sometimes full metal, sometimes painted white...
How come I have seen some -5 with the exhaust cut diagonally like the -10... is there is a difference, why the change?

Not sure if that question is asked correctly, but hope it makes sense.

All 680 through 690B have the augmenter style exhaust tube in which the exhaust pipe enters a larger duct and the air gap between them is used to pull air over the oil cooler.  Therefore, the early planes have no oil cooler doors. The later planes just have an exhaust s duct without the larger tube plus the cowl flaps.  The -10 conversion on a 690A/B exchanges the early exhaust for the later exhaust, for example.  Does this make sense?

JMA

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Re: 980 Questions
« Reply #11 on: March 14, 2018, 02:48:31 pm »
Understood... wealth of knowledge!

Shame, for another post section I know, but airspeed was well over 400kts, no pics though to prove it...

Steve binnette

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Re: 980 Questions
« Reply #12 on: March 15, 2018, 07:29:54 pm »
We’ll if we are showing 980 GS here is one 406kts.

I could do that for hours!! :)


donv

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Re: 980 Questions
« Reply #13 on: March 16, 2018, 12:19:46 am »
Steve, it looks like your pressurization does about the same as mine! Plenty of air, but 5.0psi is all it will do, so the cabin is generally about 1,000 feet above the altitude the controller indicates for that airplane altitude. Apparently it's just a controller tolerance issue.

Steve binnette

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Re: 980 Questions
« Reply #14 on: March 16, 2018, 11:53:38 am »
That’s in low flow, if I use max flow I can drop the cabin a couple hundred feet.

Max flow is not a problem on my plane since I have a enviro system.

Next 150hr I will get the leak rate checked and see if there is some simple leaks we can fix.

When low flow on an enviro system can handles the pressurization, It indidcates a nice tight cabin.
« Last Edit: March 16, 2018, 11:56:02 am by Steve binnette »