Carson speed

Any DA42 related topics.

Moderators: Rick, Lance Murray

User avatar
dgger
4 Diamonds Member
4 Diamonds Member
Posts: 217
Joined: Sun Feb 21, 2016 11:00 pm
First Name: Peter
Aircraft Type: DA62
Aircraft Registration: OEFGM
Airports: EDLN
Has thanked: 21 times
Been thanked: 39 times

Re: Carson speed

Post by dgger »

robert63 wrote:The Gyronimo App for the DA42NG gives the best range at 18.000 ft with 50% power setting. The range at ISA and 0 wind is 1.119 NM. Speed is 142 KTAS at 8.7 Gal/h. The 30 Minutes reserve is not included. The App is quite accurate for our aircraft.
Yes, but IIRC, the app uses POH data which cuts off at 50%. Or do you get data for less than 50% from the app?
User avatar
dgger
4 Diamonds Member
4 Diamonds Member
Posts: 217
Joined: Sun Feb 21, 2016 11:00 pm
First Name: Peter
Aircraft Type: DA62
Aircraft Registration: OEFGM
Airports: EDLN
Has thanked: 21 times
Been thanked: 39 times

Re: Carson speed

Post by dgger »

Henrik wrote: You can drop it down below 40%, but the high angle of attack give the airframe a sluggish feel & you feel a tendency of continuously chasing small up & down drafts, which surely can't be efficient.
This. I had the exact same experience in an NG.

Now, I am still not sure where L/Dmax might be (at MTOM, full forward CG, say). Any ideas anyone?
User avatar
robert63
3 Diamonds Member
3 Diamonds Member
Posts: 152
Joined: Sun Dec 28, 2014 8:53 am
First Name: Robert
Aircraft Type: DA42NG
Aircraft Registration: OE-FAR
Airports: LOWL
Has thanked: 14 times
Been thanked: 24 times

Re: Carson speed

Post by robert63 »

dgger wrote:
robert63 wrote:The Gyronimo App for the DA42NG gives the best range at 18.000 ft with 50% power setting. The range at ISA and 0 wind is 1.119 NM. Speed is 142 KTAS at 8.7 Gal/h. The 30 Minutes reserve is not included. The App is quite accurate for our aircraft.
Yes, but IIRC, the app uses POH data which cuts off at 50%. Or do you get data for less than 50% from the app?
No, the app starts at 50%.
User avatar
Trigger
1 Diamond Member
1 Diamond Member
Posts: 6
Joined: Wed Oct 03, 2018 11:28 am
First Name: Luis
Aircraft Type: DA42-VI
Aircraft Registration: TBN
Airports:
Has thanked: 1 time

Re: Carson speed

Post by Trigger »

Thanks for the inputs guys, I'll make some trials with 40/45/50% and figure it out before the 1000+ NM adventure. From my calculations (based on POH) with at least 20 Kts tailwind at FL120 it is doable with enough fuel to divert 100NM.
Now, I am still not sure where L/Dmax might be (at MTOM, full forward CG, say). Any ideas anyone?
From my short experience and trials on a DA42-VI MPP it's around 90/95 Kias at MTOM (1999kg) which makes some sense as the Vy is 92 (though I know Best glide speed=Vy isn't a rule in most aircrafts)
User avatar
dgger
4 Diamonds Member
4 Diamonds Member
Posts: 217
Joined: Sun Feb 21, 2016 11:00 pm
First Name: Peter
Aircraft Type: DA62
Aircraft Registration: OEFGM
Airports: EDLN
Has thanked: 21 times
Been thanked: 39 times

Re: Carson speed

Post by dgger »

Henrik wrote:You can drop it down below 40%, but the high angle of attack give the airframe a sluggish feel & you feel a tendency of continuously chasing small up & down drafts, which surely can't be efficient. 35% power is really for max endurance & not range.
Just found this on my laptop. I had tried to measure the performance for lower power settings to complement the POH below 50% and verify above 50%. Apparently, I picked a poor day and the A/P kept riding up- and downdrafts. But I like to think the story here is consitent:
  • The lower the power setting the more volatile the speeds
  • Below 40% power speeds are to volatile to be flown (despite being mapped)
  • At some point (which I suspect to be above 40% is the optimum range speed)
Image
User avatar
CFIDave
5 Diamonds Member
5 Diamonds Member
Posts: 2678
Joined: Wed Nov 07, 2012 3:40 pm
First Name: Dave
Aircraft Type: OTHER
Aircraft Registration: N333GX
Airports: KJYO Leesburg VA
Has thanked: 231 times
Been thanked: 1473 times

Re: Carson speed

Post by CFIDave »

Let me give you 2 data points:

1. When ferrying my (then brand new) DA42-VI from Weiner Neustadt, Austria to Wick, Scotland (almost exactly 1000 nm) we used a 60% power setting to fly this leg in 6 hours and 23 minutes at about 155 knots TAS at 12000 feet). Winds were essentially zero. We still had enough remaining fuel to fly 1 hour.

2. When ferrying a pre-owned Lycoming DA40 XLS to a maintenance shop, I was flying at 8500 feet at wide open throttle to achieve about 145-150 knots TAS burning 10 gph. My pilot wife flew alongside in our DA42-VI (she was my ride home!), and to maintain the same airspeed at that altitude she had to throttle back to only 44% power (on each engine) burning only about 7 gph (total, both engines)! Incredible DA42-VI fuel economy. https://www.youtube.com/watch?v=qYZmPJ-2yzI
Epic Aircraft E1000 GX
Former DA40XLS, DA42-VI, and DA62 owner
ATP, CFI, CFI-I, MEI
User avatar
ememic99
5 Diamonds Member
5 Diamonds Member
Posts: 1078
Joined: Wed Apr 09, 2014 10:31 am
First Name: Emir
Aircraft Type: DA42
Aircraft Registration: SEMAD
Airports: LDZA LDVA
Has thanked: 203 times
Been thanked: 390 times

Re: Carson speed

Post by ememic99 »

CFIDave wrote:When ferrying my (then brand new) DA42-VI from Weiner Neustadt, Austria to Wick, Scotland (almost exactly 1000 nm) we used a 60% power setting to fly this leg in 6 hours and 23 minutes at about 155 knots TAS at 12000 feet). Winds were essentially zero. We still had enough remaining fuel to fly 1 hour.
Hm... flying westbound from Austria and planning for 1000 NM, counting on zero headwinds... What was your fuel flow, 5.5 gph per engine or less (maybe 5.2 gph per engine - I don’t know exactly AE data)? Anyhow, it’s between 66.4 and 70 gallons or so (having in mind that you spent some time in climb, consuming a bit more than you get back in descent). I somehow miss to see how you had fuel for one hour more or my numbers are wrong.
Tommy
5 Diamonds Member
5 Diamonds Member
Posts: 801
Joined: Sat Aug 28, 2010 10:48 am
First Name: Tommy
Aircraft Type: DA40
Aircraft Registration: N591CA
Airports: KCGF
Has thanked: 3 times
Been thanked: 33 times

Re: Carson speed

Post by Tommy »

User avatar
CFIDave
5 Diamonds Member
5 Diamonds Member
Posts: 2678
Joined: Wed Nov 07, 2012 3:40 pm
First Name: Dave
Aircraft Type: OTHER
Aircraft Registration: N333GX
Airports: KJYO Leesburg VA
Has thanked: 231 times
Been thanked: 1473 times

Re: Carson speed

Post by CFIDave »

ememic99 wrote:
CFIDave wrote:When ferrying my (then brand new) DA42-VI from Weiner Neustadt, Austria to Wick, Scotland (almost exactly 1000 nm) we used a 60% power setting to fly this leg in 6 hours and 23 minutes at about 155 knots TAS at 12000 feet). Winds were essentially zero. We still had enough remaining fuel to fly 1 hour.
Hm... flying westbound from Austria and planning for 1000 NM, counting on zero headwinds... What was your fuel flow, 5.5 gph per engine or less (maybe 5.2 gph per engine - I don’t know exactly AE data)? Anyhow, it’s between 66.4 and 70 gallons or so (having in mind that you spent some time in climb, consuming a bit more than you get back in descent). I somehow miss to see how you had fuel for one hour more or my numbers are wrong.
I was going from memory, but to be correct, here's the log file for the flight:
http://www.diamondaviators.net/reports/flights/3935
Epic Aircraft E1000 GX
Former DA40XLS, DA42-VI, and DA62 owner
ATP, CFI, CFI-I, MEI
User avatar
ememic99
5 Diamonds Member
5 Diamonds Member
Posts: 1078
Joined: Wed Apr 09, 2014 10:31 am
First Name: Emir
Aircraft Type: DA42
Aircraft Registration: SEMAD
Airports: LDZA LDVA
Has thanked: 203 times
Been thanked: 390 times

Re: Carson speed

Post by ememic99 »

It looks like 33.58 gallons per engine i.e. 67.16 total i.e. 9.24 gallons left (if 76.4 is usable fuel). The rest of log looks pretty standard - 153 KTAS is consistent with achieved FF.
Post Reply