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  #21  
Old 09-10-2017, 11:32 PM
AlanTN AlanTN is offline
 
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I stated above: Figuring 19.8 gallons/4.8 gph = 4.125 hours.... x 117 knots x 1.15 mph/knot = a range of 555 miles. That is about what I would expect, and substantially better than the downgraded numbers (433 miles) that Van's now claims for the RV-12.

Quote:
Originally Posted by vic syracuse View Post
Perhaps I am reading your post wrong, but there's no way I would calculate "range" assuming dry tanks. That would be a real pucker factor for me.
I know the regs say we need 30 minutes of fuel remaining for day VFR for planning purposes, but I always land with 1 hour of fuel in the tanks, no matter what I am flying. You just never know if the the ruwway gets closed upon your arrival and you have to divert, or stronger winds than forecast, etc.

That's just my practice and in no way meant to be judgmental of others.

Vic
Vic, in the Section 5-6 of the RV-12 POH under 'Cruise Performance,' dated 03/07/16, in which the rightmost column is titled 'Range' it say below:

'NOTES: 1) No fuel allowance is made for take-off, climb, descent, or reserve.'

That is the only consistent way I know of calculating and publishing range numbers and that is apparently the way Van's did it.
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Last edited by AlanTN : 09-10-2017 at 11:34 PM.
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  #22  
Old 09-11-2017, 07:20 AM
KatanaPilot KatanaPilot is offline
 
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Quote:
Originally Posted by AlanTN View Post
I stated above: Figuring 19.8 gallons/4.8 gph = 4.125 hours.... x 117 knots x 1.15 mph/knot = a range of 555 miles. That is about what I would expect, and substantially better than the downgraded numbers (433 miles) that Van's now claims for the RV-12.



Vic, in the Section 5-6 of the RV-12 POH under 'Cruise Performance,' dated 03/07/16, in which the rightmost column is titled 'Range' it say below:

'NOTES: 1) No fuel allowance is made for take-off, climb, descent, or reserve.'

That is the only consistent way I know of calculating and publishing range numbers and that is apparently the way Van's did it.
I guess RV-12 pilots are expected to air launch their airplanes and do a Bob Hoover Shrike Commander arrival!

The engineer in me would still like to see a competent and accurate answer to Alan's range question posted here and in the previously closed thread.
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  #23  
Old 09-11-2017, 08:00 AM
vic syracuse vic syracuse is offline
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On the first leg of the trip to the Expo I flew 2.7 hours and put in 15.4 gallons of fuel when I landed. The routing was from GA04 to KCTJ and a landing at KHVC. My figures show that as 276NM.

We were at gross weight (1320 lbs) and climbed to 3500' for most of the trip. Midway through the trip we climbed to 4500' for about 35 minutes for radar coverage (I always use flight following). RPM's were at 5400 for most of the trip, except climbs and descents.

That's as accurate as you are going to get from me for now. All of the other legs had demo flights on either end without filling up.

I think this particular 912 is running overly rich, as the EGT is low at 1100-1200 degrees. Rotax recommended is in the 1400's. On my Kitfox's with the 912 I did experiment with the positioning of the needle clips and was able to achieve the recommended EGT's. I have not had time to experiment with this one yet.

Vic
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  #24  
Old 09-11-2017, 04:25 PM
AlanTN AlanTN is offline
 
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Quote:
Originally Posted by KatanaPilot View Post
I guess RV-12 pilots are expected to air launch their airplanes and do a Bob Hoover Shrike Commander arrival!

The engineer in me would still like to see a competent and accurate answer to Alan's range question posted here and in the previously closed thread.
Krea, because there are so many possible variables, range numbers are generally given based upon the total amount of usable fuel. It can easily be calculated by flying for one hour at the desired altitude and conditions and precisely metering fuel consumption, then using the distance covered after correcting for any wind, and the airspeed to calculate the range.

It is up to the individual pilot to allow for normal consumption for takeoffs and landings and to determine how much reserve to allow beyond their expected landing time for unforeseen circumstances. Personally, 30 minutes would not be good enough. I would feel much more comfortable with a minimum of an hour of reserve fuel.
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Last edited by AlanTN : 09-11-2017 at 04:34 PM.
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  #25  
Old 09-11-2017, 07:02 PM
KatanaPilot KatanaPilot is offline
 
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Quote:
Originally Posted by AlanTN View Post
Krea, because there are so many possible variables, range numbers are generally given based upon the total amount of usable fuel. It can easily be calculated by flying for one hour at the desired altitude and conditions and precisely metering fuel consumption, then using the distance covered after correcting for any wind, and the airspeed to calculate the range.

It is up to the individual pilot to allow for normal consumption for takeoffs and landings and to determine how much reserve to allow beyond their expected landing time for unforeseen circumstances. Personally, 30 minutes would not be good enough. I would feel much more comfortable with a minimum of an hour of reserve fuel.
Most certified airplanes that I've flown provide range data with takeoff, climb and descent included. The conditions assumed are provided (for example - one 170 pound pilot). Sometimes, a specified reserve is also included. To me, providing range data that has no provision for takeoff, climb and descent is ambigous and basically useless. That information has no bearing on any possible operation of the aircraft. If you give me a fuel burn for takeoff, climb, cruise and descent, then I can figure range with my personal reserves. I certainly don't need Boeing or even Cessna type charts.
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Last edited by KatanaPilot : 09-11-2017 at 07:03 PM. Reason: Removed text
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  #26  
Old 09-11-2017, 07:14 PM
AirHound AirHound is offline
 
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Quote:
Originally Posted by vic syracuse View Post
On the first leg of the trip to the Expo I flew 2.7 hours and put in 15.4 gallons of fuel when I landed. The routing was from GA04 to KCTJ and a landing at KHVC. My figures show that as 276NM.

We were at gross weight (1320 lbs) and climbed to 3500' for most of the trip. Midway through the trip we climbed to 4500' for about 35 minutes for radar coverage (I always use flight following). RPM's were at 5400 for most of the trip, except climbs and descents.

That's as accurate as you are going to get from me for now. All of the other legs had demo flights on either end without filling up.

I think this particular 912 is running overly rich, as the EGT is low at 1100-1200 degrees. Rotax recommended is in the 1400's. On my Kitfox's with the 912 I did experiment with the positioning of the needle clips and was able to achieve the recommended EGT's. I have not had time to experiment with this one yet.

Vic
I'm in the 1200 range with a 40-100 degree dif burning roughly 5.7 at 5400. What do the carb mixture screws do for us?
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  #27  
Old 09-11-2017, 07:39 PM
rk2436 rk2436 is offline
 
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Nothing,leave them alone. Should be set at factory. They will adjust the idle mixture if you needed.
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  #28  
Old 09-12-2017, 07:02 AM
vic syracuse vic syracuse is offline
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Quote:
Originally Posted by rk2436 View Post
Nothing,leave them alone. Should be set at factory. They will adjust the idle mixture if you needed.

I don't think "nothing" is the right answer regarding the carb screws. The idle mixture is usually adjusted when doing a carb sync, which should be checked annually.

The egt's are adjusted as per the manual by adjusting the clips on the needle inside the carb. The proper range is around 1470 F with a max of 1560 F for cruise and a max of 1616 F for takeoff.

I know it might sound a little picky, but I used to adjust my 912's between summer and winter flying as it made a big difference.

Vic
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  #29  
Old 09-12-2017, 11:53 AM
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f1rocket f1rocket is offline
 
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I find all the discussion regarding the range of the -12 somewhat amusing. I'm not picking on anyone, but if you fly the -12 much cross country, you find that the ACTUAL range on any particular leg of flight is strongly impacted by cruise RPM, altitude, winds aloft, weight, and temperature. This took a little getting used to when I moved from the Rocket or other RV models to the -12.

When I planned a flight, I rarely landed at the airport I originally planned. I usually encountered flight conditions different than what the flight planning software thought and thus my range was either diminished or extended accordingly.

The simplest thing to do was to head in the direction I wanted to do, fly for an hour or so, reset the fuel computer to the actual fuel level in the tank, and then recalculate my current range with my current fuel. All this is easy to do with the Dynon. I then took full advantage of the airport information stored in the Dynon to find an airport that was acceptable to me given my desired services and reserves.

Only once did I encounter a problem and that was out West on Memorial Day when the airport I landed at had inoperable fuel pumps. I had to squeeze into the next airport with marginal fuel remaining.

You can consistently see 4.5 to 4.9 GPH at 5400-5500 RPM. How that translates into range is a day to day thing.
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  #30  
Old 09-12-2017, 02:21 PM
RFSchaller RFSchaller is offline
 
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With all the restricted airspace in the southwest and wide open spaces a busted fuel pump at an FBO can easily leave you stranded if you cut margins close out here. I landed at a small strip near Monument Valley for gas, and the couple running the place were like shut-ins. They were ecstatic to see an unfamiliar face to talk to. Things can get pretty isolated. Not like the good old days when I learned to fly in Illinois with an airport every 50 miles in every direction.
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