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The "8 Knot Mod"

Re: The "8 Knot Mod"

Well, Richard if you think of it. You can get just about 20MP or less at about 10k-12K with the throtle wide open. Even if you set RPM to 2400 or 2500 at those altitudes you will not get much IAS from the power plants. The TAS may be much higher though.
 
Re: The "8 Knot Mod"

Could it have anything to do with Maneuvering Flight Speed or the Turbulance Penetration Speed?
 
Re: The "8 Knot Mod"

"You can get just about 20MP or less at about 10k-12K with the throtle wide open".

Alex:

True. But it would not make sense to optimize the aircraft for the outer edge of the flight envelope. 6 to 8 K is where the 114 is happiest so this is where you would expect optimization.

But then, I am far from being an expert....

Richard
 
Re: The "8 Knot Mod"

rrolland said:
"You can get just about 20MP or less at about 10k-12K with the throtle wide open".

Alex:

6 to 8 K is where the 114 is happiest so this is where you would expect optimization.

Richard
Click to expand...
Very True.
 
Re: The "8 Knot Mod"

Hi All,

Thanks for the pics and thoughts thus far, they are very helpful.

Keep them coming!

Jim
 
Re: The "8 Knot Mod"

Jim,

Here is my information on a straight 112

Alt: 5500 feet
IAS: 132
TAS: 140
OAT: -10
Approx Weight: 2445

Trimmed for level flight
 

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Re: The "8 Knot Mod"

Here is my input. This was flying at 8000ft, 128KIAS, -8C, ~2900lbs.

Hope this helps...

Cheers,
Jon
 

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Re: The "8 Knot Mod"

Dave

132kts IAS on a straight 112. What were your power settings?

Please tell me your secret, I have a big smile on my face if I'm indicating 125KIAS at 5500' on a cold day. Normal is around 120KIAS, unless in a shallow dive.
 
Re: The "8 Knot Mod"

Lawrence: I've got a TC, same airframe as you. I almost always see 118IAS at 65% power. that's with big tires and the cowl flaps open about 20%. I'm hoping to hit 120IAS when the Cowl flap problem is taken car of...
 
Re: The "8 Knot Mod"

Dave said:
Jim,

Here is my information on a straight 112

Alt: 5500 feet
IAS: 132
TAS: 140
OAT: -10
Approx Weight: 2445

Trimmed for level flight
Click to expand...

Dave! 140 Knots TAS from a 30-year-old straight 112? Methinks you rotated that wheel on your trusty E6B the wrong way, or you have found ways to break the rules of physics.
 
Re: The "8 Knot Mod"

I believe I was flying 24 squared.

I guess it's possible my AS indicatr is bad, but I often see IAS of 130-135. I flight plan based on 130 which seems to work well.
 
Re: The "8 Knot Mod"

Scott - several others have reported similar in the FAQ. Good rigging, cool temps, and reduced weight can work wonders. I see similar.

      • 4500ft, 24MP, 2500rpm. TAS 140 knots at 11.8gph, 11C. 2550lbs
      • 4500, 24MP, 2400rpm, TAS 140 knots at 11.5gph, 5C, 2340lbs
      • 5000, 24MP, 2430rpm, TAS 136 knots at 10.3gph, -4C, 2550lbs
 
Re: The "8 Knot Mod"

Glenn

As you probably know, we suffer from a lack of Commander experience in our engineering departments on this side of the Atlantic. I've just been through a rigging adjustment as part of my anual and it is now supposed to be to spec. We also closed some gaps in the cowling, gear doors etc. This all made a difference, I'm sometimes getting 125KIAS at 5000' on 24/2400 at 1 degree C which was a gain of around 7 Kts. TAS would calculate to be 132KTAS. The question: is there anything else that I can do without secondary modifications which could get it up to the sort of speeds yourself and Dave are seeing?

Do you think that the longer wing on the B and TC models which, I guess, provide more lift are actually slowing it down?
 
Re: The "8 Knot Mod"

I'm pretty sure the longer wing will result in greater lift, higher usefull load, but, a slower airspeed ... everything is a compromise.
 
Re: The "8 Knot Mod"

Lawrence - Paul nailed it. The longer wing is more drag. Different story at altitude. Those that have the longer wing with turbo or turbo normalizer can probably give some pretty impressive numbers from the flight levels. I've always felt the 112B with the Hot Shot STC was a great combination for cross country travel.

Those of us with the straight 112's top out around 11-12K.
 
Re: The "8 Knot Mod"

gmores said:
Scott - several others have reported similar in the FAQ. Good rigging, cool temps, and reduced weight can work wonders. I see similar.

      • 4500ft, 24MP, 2500rpm. TAS 140 knots at 11.8gph, 11C. 2550lbs
      • 4500, 24MP, 2400rpm, TAS 140 knots at 11.5gph, 5C, 2340lbs
      • 5000, 24MP, 2430rpm, TAS 136 knots at 10.3gph, -4C, 2550lbs
Click to expand...


Remarkable.
 
Re: The "8 Knot Mod"

Alan ... I think you meant to ask Dave?
 
Re: The "8 Knot Mod"

I know this is getting off the thread and I promise I'll take some photo's of my elevators at the weekend if it stops snowing, however...

Allen,

What numbers do you see at 75%? I get almost no difference in speed, just burn more fuel.
 
Re: The "8 Knot Mod"

My readings were at 75% power. At least I believe so (just read a little on this today)

My flight was 24 squared at 5500 feet. I'm pretty sure the book calls for 24 squared at 6000 feet to achieve 75%
 
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