What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

High Density Altitude Operations with RV-12

T

TThurston

Well Known Member
This has been a HOT summer in Utah. Most days it's 70 degrees at 6 a.m. and often 80 degrees by 9 or 10. Most of the airports nearby are at 4,300 to 5,000 MSL. Many of the nearby moutain ranges are between 10,000 and 12,000, but following canyons and avoiding peaks, one can fly most places at a cruise altitude of 7,500 to 10,500.

I have the tail about done on an RV-9A, but have wondered about starting over with a RV-12 in order to finish sooner. However, I wonder if the performance of the RV-12 would be adequate for the density altitudes I would see for much of the summer. Any thoughts?
 
I am high too

I will be flying my RV12 out of the Denver area, Rocky Mountain Regional KBJC, to be specific. Our field elevation is 5460 and it does get warm here too so density altitude is a concern. I do have lower elevations East but to my West 8 to 10K feet is common too. I just finished some transition training with John Albury in Texas at 800ft field elevation so I going to experience my high altitude airport soon. I know there is a guy (John I believe) in Salida, CO. and their field elevation is upward in the 7000ft range but in the morning I am sure it is fairly cool even during this time of year. He has been flying his RV12 in the Arkansas Valley for a few years now.

I was told at a recent light sport expo we had at Front Range airport here in the Denver area that the RV12 performed well on the trip from Oregon to Denver, but there was a noticeably longer runway usage at the higher altitudes during his trip. A Vans representative came out in one of the factory built Blue planes.
 
I too am building a RV-12 down at Meadow Lake in Colorado Springs. I currently own a Rotax 912 based Aero AT-4 or Gobosh 700. The RV-12 is actually lighter in gross and having flown both planes I can say they are very similar.

I regularly fly my Gobosh out of KFLY with DA at 9000-10000 feet. I also have flown into both Buena Vista and Leadville with no problems. The longer runway is helpful to be sure. I have flown my Gobosh into Kelly air park for their pancake breakfast the past couple years. This year was getting hot and DA was getting high when I took off. I was about 20 pounds under gross. That runway is about 3800 feet. I was able to get off with a margin of safety and climb at about 400-500 FPM on departure.

I know this doesn't directly address RV-12 high altitude operations but since the Gobosh is so similar with the same engine I think I is a viable extrapolation.

Carl
 
Most of the 912S powered LSA work well at higher DA, so I expect the -12 to do so as well. I practiced at BZN the same day and our CT far outperformed a DA20 even though it was later in the way (with higher DA).

Tips:

* Make sure your prop is pitched properly. Search for lots of discussion, but you should be seeing at least 5200 RPM static at WOT.

* Go light. 100 lb is a large % of weight in an airplane with 1320 lb MGTW.

* Get practice and instruction.

* Start with plenty of runway until you know your specific airplane performs at different DA.

TODR
 
I noticed Flagstaff has a Density Altitude display now, anyone take off at a DA of say....8500-9000'?

How'd it go?
 
T/O and Climb Chart Is Pressure Altitude

John Clark said:
You are "off the chart" at a DH of 9000.

http://www.vansaircraft.com/pdf/revisions/RV-12/User_Manuals/POH_180.pdf

Then go to Chapter 5, chart 5-3

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
Click to expand...

The T/O and Climb chart is in pressure altitude. At 8000 ft pressure altitude and 100F, DA is 12,634. So at 8000ft PA and 60F, DA is 9967ft and the T/O ground roll is 1092ft, 2511ft over 50ft obstacle, with a rate of climb of 416fpm, sufficient performance I would say.

The landing chart is in Density Altitude and only goes to 7500ft DA.
 
Just for comparison, a C-150 at 2500' on an 85F day has the following performance:
T/O gnd run 1001'
Over 50' obstacle at 1830'
ROC of 490 fpm
DA is 4,827'

RV-12 at 8000' on a 40F day
T/O gnd run 1010'
Over 50' obstacle at 2226'
ROC of 509 fpm
DA is 8,634'

So it is comparable to flying a C-150 out of Fox Field (KWJF) near Lancaster CA during the morning on a summer day which is where I got my license.
 
First Flight

I took my Rv12 up for the first time last evening. The conditions were just to nice to wait until this morning. So I wanted to report on the high altitude conditions and the plane performed very well.

When I set the Baro the elevation was 5580 and with the cooler temperatures in the 80's density altitude was not a factor. My static RPM w/WOT was set at 5140 and the plane climbed well on take off. I maintained 60kts and the RPM was 4940. Once I leveled out at 6800 I pulled the power back to 21inches of MP to let things settle for a few laps around the pattern. The fuel pressure was the only thing in the yellow at 1.9-2.0 and everything else was very normal.

When I did go to WOT for a stretch the RPM rose to 5540 and the temps went up slightly. I didn't stay there long but did have a slightly heavy left wing but nothing severe. The ball pushed out to the right about a quarter, but no weird vibrations. 30 minutes and I was back on the ground, cowl off and everything looked good. I leave my prop where it is for now and research the fuel pressure.:D
 
Congratulations Pat!

I am waiting out the rain and winds here in St Louis for my first flight.

It was nice meeting you during transition training with Jetguy..
 
Be sure to email vans that you are flying! And ask what number flying RV12 you are and post that.
 
You must log in or register to reply here.
Back
Top