Grand Canyon Anyone?

[AgentCheese]

Gyro experts,

My bride and I are planning on visiting the Grand Canyon this spring in May. I was wondering if anyone has ever flown the special VFR GA corridors over the canyon in a 914 gyro. We have a Magni M16 with a 914. It appears that the absolute min altitude in the corridor is 10,500 MSL. Service/Absolute ceiling in an M16-914 is 11,500/13,000. Depending on OAT, density alt will be close to that.

Safety first - I plan on flying close to the canyon edge to be able to reach the plateau in the event of engine failure. We will be most likely be leaving from Valle, and if we can't make alt prior to the corrider, we will divert to skirt around the special airspace.

Any thoughts, ideas, advice will be greatly appreciated.

Thanks!

Jon

 

[WaspAir]

In May in Arizona, you are pretty much guaranteed an OAT that will give you substantially higher density altitude there.

My Colorado home base field is at 7040 feet elevation, and the AWOS on any pleasant day announces DA between 8300 and 9800.

I don't expect you to have much margin with the numbers you report.

 

[PeterFromLA]

Enjoy the Grand Canyon from the ground, then go to Zion and fly freely around some magnificent vistas...

 

[DavePA11]

Where is Zion?

 

[GyroChuck]

Where is Zion?

Zion National Park (U.S. National Park Service)

www.nps.gov

 

[Tyger]

It appears that the absolute min altitude in the corridor is 10,500 MSL. Service/Absolute ceiling in an M16-914 is 11,500/13,000. Depending on OAT, density alt will be close to that.

Along the lines of what WaspAir wrote:
"...remember that the standard lapse rate (the rate at which temperature normally decreases with increasing altitude in unsaturated air) compounds the problem somewhat. At sea level, the standard temperature is 59 degrees Fahrenheit, however, at 10,000 feet MSL, the standard temperature is only 23 degrees. This means that at Leadville, Colorado (elevation 9,927 feet) when the temperature is only 24 degrees, the density altitude is already above the field elevation."

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/tips_on_mountain_flying.pdf

Standard temperature at 10,500 ft is 15-(10.5x2) = -6ºC (about 21ºF)
By my calculations, if you are flying at 10,500 ft on a standard pressure day where your outside air temperature is 15ºC (59ºF), your density altitude would be: 13,020 (10,500 + (21x120)), which would be over your absolute ceiling.
If your OAT were 0ºC (freezing!), your DA would still be 11,220 (10,500 + (6x120)), or just under your quoted service ceiling.

PS Keep in mind that that 10,500 ft altitude is for flying the corridors southbound. If you are going northbound (say, from Valle), the minimum will be 11,500.

 

[Resasi]

Now that what I call useful feedback/advice and the value of this Forum.

 

[AgentCheese]

Thanks for replies everyone. Like I stated in OP, safety first. Will have to keep an eye on temps, but it doesn't look possible at this point. Just curious if anyone has flown the corridors in a gyro, ever.

 

[Tyger]

I don't know if anyone has, but I think you'd have to be pretty brave to try it, partly because gyros' glide ratios are so much worse than most airplanes'.

If you assume a glide ratio of 5:1 (which is rather optimistic), to be able to glide from the middle of a 10nm crossing to the south rim (elevation about 7000 ft), you would need to be at least 6000 ft higher than the rim, or something over 13,000 ft actual altitude (standard temp: 12ºF).
The north rim is, of course, even higher.

 

[DavePA11]

Tyger - for 1 mile drop you can glide 5 miles in your gyro without power? I would think it’s much less…

 

[Tyger]

Yes, in theory. Magni lists the M16 glide rate as about 1000 ft/min (vertical) at best glide speed of 60-65 mph (5280+ ft/min).
Seems about right from my own personal experience.

PS A key factor in such situations is going to be the wind. If you have a tail wind, you'll go much further, over the ground, than the glide ratio would imply. With a headwind, it will be much less, of course.

 

[AgentCheese]

OK - Flew from St. Louis MO to Flagstaff then up to Grand Canyon Junction. Quite the adventure all on it's own. It was 90+ during the day, and though I am sure I could have made 12.5 in the morning, but that is really too high to see much detail. Plus it is an extremely harsh environment which I didn't fully appreciate till I got out there. Had a great time flying around Red Butte, Valle, and Flagstaff, and giving locals some rides. Got to hanger with some really cool mates!

We spent our time hiking down the South Kaibab and riding bikes along the South Rim.

 

[Tyger]

It was 90+ during the day, and though I am sure I could have made 12.5 in the morning, but that is really too high to see much detail. Plus it is an extremely harsh environment which I didn't fully appreciate till I got out there.

By 12.5 you mean 12,500 feet? What were the temperatures in the morning?

 

[jeffh]

Looks like an interesting trip. Love the cars in the hangar.

 

[AgentCheese]

By 12.5 you mean 12,500 feet? What were the temperatures in the morning?

Yes - 12,500, but I meant 11,500. I made it to 10,500 on the way from Flagstaff to Valle w/o any issues in the late afternoon on our first day. Temps in the mornings were cool - one morning it was 36 deg F.

But in the hot afternoons in the high density alts, the gyro is very 'mushy'. I had a fairly large gentleman want me to take him for a ride at Double Eagle in Alburquerque and it was 96 deg and the density alt was 9500. I told him "not today". I really dislike flying at those high density alts!

 

[Tyger]

Yes - 12,500, but I meant 11,500. I made it to 10,500 on the way from Flagstaff to Valle w/o any issues in the late afternoon on our first day. Temps in the mornings were cool - one morning it was 36 deg F.

But in the hot afternoons in the high density alts, the gyro is very 'mushy'. I had a fairly large gentleman want me to take him for a ride at Double Eagle in Alburquerque and it was 96 deg and the density alt was 9500. I told him "not today". I really dislike flying at those high density alts!

Ya, if your density altitude is 9500 on the ground, just 2000 AGL puts you at your service ceiling. Good call not to take up the "large gentleman".

Standard temperature at Double Eagle would be 15-(5.8x2) = 3.4ºC. At Valle it's just 3ºC – pretty darn close to that 36ºF !