Jaybird180
Final Approach
I wonder if this question is addressed here, but in a different fashion (I don't get the reason for 2 power changes).
Learning new plane: Diamond DA-40 w/G1000
- Thread starter Jaybird180
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I wonder if this question is addressed here, but in a different fashion (I don't get the reason for 2 power changes).
TMetzinger
Final Approach
It's not two power changes, it's two settings - one if you're continuing to climb and the other if you're staying in the pattern.
Looks like a Vy initial climb with a nose-over at a "safe" altitude to retract flaps, turn off fuel pump, etc. All of which we agree on. The question still unanswered is what the "safe" altitude is..
We teach the same thing, initial climb at Vy (no Vx published for the DA40), then at some point (I suggest 800-1000 AGL) you either level off and reduce power for the pattern, or you lower the nose and maintain power for a "cruise climb", which we usually specify at 2500 RPM and 80-85 KIAS.
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Jaybird180
Final Approach
Jaybird180
Final Approach
Ok, now that I think about it, I'm climbing out at about 85kts when I retract flaps. No sink, just a push back in the seat.
flyingcheesehead
Taxi to Parking
No, that's Vg. Vx is blank.
FWIW, the Vx tag on the G1000 is set at 64 KIAS. With Vy being 66, it probably doesn't matter so much that Vx isn't officially published.
Jaybird180
Final Approach
Take another look sir. The posted copy may be blurred a bit, I can send if you like.
Jaybird180
Final Approach
Question about TIS Service:
I was told the DA40 I'm flying has traffic. My understanding is that is a standard part of the ADS-B services the FAA is building. It is also my understanding that ADS-B has a weather component that also comes with it. The DA40 manual states that XM Weather is optional.
Q1: Why would someone want to have ADS-B weather and XM Weather in the same plane?
Q2: Is it possible that weather capabilities ARE in the aircraft I'm flying but the person who provided that information may be mistaken?
I was told the DA40 I'm flying has traffic. My understanding is that is a standard part of the ADS-B services the FAA is building. It is also my understanding that ADS-B has a weather component that also comes with it. The DA40 manual states that XM Weather is optional.
Q1: Why would someone want to have ADS-B weather and XM Weather in the same plane?
Q2: Is it possible that weather capabilities ARE in the aircraft I'm flying but the person who provided that information may be mistaken?
TMetzinger
Final Approach
No, you should notice that Vx is BLANK.
gprellwitz
Touchdown! Greaser!
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I took another look, and I think Kent is reading it correctly. The first "row" has two lines in it. The first line is Vg and is missing a closing parenthesis. Is lists speeds for all three weights. The second line is Vx and does not list any speeds at all.
All PDF copies of the POH and Checklist from Diamond show that Vx is unspecified. This is because for this plane, Vx and Vy are too close together to matter.
ADS-B weather replaces the need to have XM weather. XM would be useful where you don't have ADS-B coverage.
The FAA states:
Yes. ADS-B’s Flight Information Services-Broadcast (FIS-B) provides all of the information you would get with an XM basic subscription, and more. In fact, at no subscription cost to the user, the ADS-B FIS-B product today is comparable to the mid-to-high-level XM subscription. The FAA currently is discussing with the vendor the possibility of adding even more “no-cost” products to the FIS-B service, such as:
* Lightning
* Turbulence NOWcast
* Icing NOWcast
* Cloud Tops
* 1 minute AWOS – uplinked every 10 minutes
The traffic you get in the DA40 is likely TIS-B off of your mode-s transponder. Mode-S won't pull in weather, so if you don't have XM, and don't have ADS-B In, then you don't have weather.
Yup. Plus, that's the checklist. The checklist is not regulatory. TCDS and AFM do not show a Vx speed.
Jaybird180
Final Approach
Okay so you're saying that Best Glide <> Vx?
(Dr Leonard McCoy voice) DAMMIT JIM
TMetzinger
Final Approach
I'm saying that Vx DOES NOT EXIST for that airplane (it's not in the TC or the AFM).Okay so you're saying that Best Glide <> Vx?
(Dr Leonard McCoy voice) DAMMIT JIM
You'll note that the AFM doesn't have a "short field" takeoff section, though it does have a "short field" landing section.
Gary F
Final Approach
It exists but it has not been published by Diamond.
That's because other than brakes, power full, release brakes, every takeoff is in short-field configuration. TO flaps are 24 degrees. Try taking off without flaps and it's a pretty flat climb.
Jaybird180
Final Approach
I recall reading a Deakin article advising against full power static run-ups. What's your opinion on that as it applies to the above statement?
TMetzinger
Final Approach
I follow the AFM.
TMetzinger
Final Approach
Yep, the takeoff configuration is already as "short field" as it's gonna get.
EdFred
Taxi to Parking
Deakin is not God. Keep engine temps where they should be, and you're fine.
denverpilot
Tied Down
Don't get me started on CFIs with "dueling pet-peeves"... been there done that... even within the same club where they sit in meetings together to discuss "standardization".
denverpilot
Tied Down
Well, I just learned something new, indirectly. I thought Vx would be in the POH of anything Certificated. Hmmph. Interesting.
flyingcheesehead
Taxi to Parking
A lot of what you want to know depends on how your airplane is equipped.
Since you specified that it is a G1000-equipped plane, there are three potential units that could be used for datalink: The GDL 69, GDL 69A, or GDL 90. By far the most common on the DA40's is the GDL 69A, which supports XM datalink and radio (entertainment channels). The straight GDL 69 does not have the radio channels, only the weather datalink. The GDL 90 is an ADS-B datalink unit.
To answer your Q1, there's no reason to have both and I'm not sure it's even possible to plug both a GDL 69(A) and a GDL 90 into the G1000 simultaneously to do such a thing. As for Q2, you should be able to find what the plane is set up for in the AUX pages on the MFD.
As far as traffic goes, you probably are NOT getting traffic info via ADS-B, you're probably getting it through TIS via a Mode S transponder (GTX 33). This only works with some TRACON radars, so if you fly away from the megalopolis that is the DC-BOS corridor you may find that the G1000 will vocalize "Traffic Unavailable" or "TIS Unavailable" along with a small box with yellow text saying the same thing on the MFD and "UNAVAILABLE" in the middle of the traffic page.
If you want to know what's really going on, use the large FMS knob on the MFD to switch to the AUX page group and then the small FMS knob to switch to the page that shows the various software versions and such that are present on the various G1000 components. You should be able to determine whether you have a GTX 30 or GTX 33 transponder (the latter is Mode S and would be providing the traffic feed) and whether you have a GDL 69, GDL 69A, GDL 90, or none of the above. There's also an XM Information page that should let you know what subscription level is currently active. If you do have weather, the third page in the NAV group (one click to the right of the traffic page) will be a weather map and will let you display radar, echo tops, winds aloft, and many other weather products.
Hope this helps!
flyingcheesehead
Taxi to Parking
No, Vg is not equal to Vx.
BTW, note that it's not possible for Vx to be faster than Vy. If Vx had both a higher angle and a higher airspeed, it would also have a higher rate of climb, and since Vy is the best rate of climb, Vx cannot have a higher rate of climb than Vy, thus it also cannot be at a faster airspeed, by definition.
EdFred
Taxi to Parking
It can be if you fly backwards, as that would be a negative vector, and -56kts is higher than -70kts.
flyingcheesehead
Taxi to Parking
Well, since theoretically Vx is 64 (based on the G1000 "Vx" tag on the airspeed tape, since it's not published anywhere else) and Vy is 66, and even the ATP PTS doesn't have an airspeed standard of less than 5 knots, Vx is kind of meaningless.
Jaybird180
Final Approach
I think I understand where you're coming from, but would you mind if I take a stab at clearing it up for posterity?
Vx can't be higher than Vy because of the simple physics of being at a higher AoA.
However there are cases where a faster airspeed can be suboptimal oppose to Vy. Example: We race to 2000AGL using same make/model aircraft on parallel runways. I fly Vy and you fly Vy+20kts. I will beat you to 2000AGL.
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Jaybird180
Final Approach
Fantastic!
flyingcheesehead
Taxi to Parking
It's not even that difficult. You've probably seen this graphic before:
That represents where the plane would be flying Vx or Vy for an equal length of time. Now, take a look at this slightly modified version:
In this version, the red line represents what would happen if Vx were faster than Vy. Due to the higher angle combined with the increased airspeed, the rate of climb would be greater - But since Vy is by definition the best rate of climb, this is not possible. Likewise, the blue line represents Vy being slower than Vx (same thing) - If Vy were slower than Vx, in the same amount of time the plane climbing at Vx would have a higher rate of climb, and again, this goes against the definition of what Vy is.
Make sense?
True - But you'd be surprised how little of a difference that can make sometimes. For example, on an Archer, Vy is 76 knots. However, if you push the nose over and accelerate to 90 knots, you'll maintain nearly the same climb rate and you'll not only be much nicer to your engine (keeping those CHT's cool), you'll get to your destination faster. Unless, of course, your destination is 2000 above airport elevation.
(I make the airport elevation distinction because technically, if both planes in your example were flying towards descending terrain, I could beat you to 2000 AGL even at Vy+20. 
)Attachments
Jaybird180
Final Approach
(Jed Clampett voice) You went and done cheated by using a pictorial representation (LOL).
Were saying the same thing
Were saying the same thing
flyingcheesehead
Taxi to Parking
Good. But bringing AoA into the mix confuses things somewhat, IMO - The difference in attitudes between Vx and Vy is larger than the difference in AoA's. But using that graphic, it makes perfect sense to anyone.
TangoWhiskey
Touchdown! Greaser!
Somebody got this quick close up video of it on the ramp in Austria within the past week:
I always thought that flaps came up clear of obstacles.
TMetzinger
Final Approach
I teach that way... the problem is when the flaps are forgotten. Many airplanes either won't pass Vfe, or take a long time, after the first level-off. DA40 will zip right past it on the first level-off.
No, Vx FLAPS UP is lower than Vy which I believe is specified with flaps in the POH.
flyingcheesehead
Taxi to Parking
Vx is not specified in the POH for any condition. Vy is specified as 66 KIAS at 2535 pounds with flaps in the takeoff position.
While they don't specify a Vy for flaps up, they do specify a "cruise climb" speed of 73 KIAS after retracting flaps. Not much of a cruise climb! I go more like 90 once flaps are up.
TMetzinger
Final Approach
OW, you fat penguin!!!!That can be overcome with the judicious use of a ruler, Nun style...
Jaybird180
Final Approach
I've been playing around with a W&B calculator I made with excel, using the POH figures...how do you get this airplane to balance? Using the figures I would have used for my XC (that I didn't do), I would have to be creative.
I likely have flown with it forward CG range with the CFI before either of us checked the W&B.
I likely have flown with it forward CG range with the CFI before either of us checked the W&B.
The ones I flew in had this BEW:
Here's an example with me and a buddy. With 2 heavy guys, you have to put in at least 20 pounds of bags to be in CG. Past that, and the weight increase just follows up the line.
The tail boom is pretty long, so controlability is good at the edge of the CG envelope.
Code:
1,743.55 97.15 169,377.59
1,690.31 95.70 161,755.42
1,683.30 96.06 161,702.57Here's an example with me and a buddy. With 2 heavy guys, you have to put in at least 20 pounds of bags to be in CG. Past that, and the weight increase just follows up the line.
The tail boom is pretty long, so controlability is good at the edge of the CG envelope.