Flying to Tehachapi

[cessna170bdriver]

I thought that the Pilot Lounge would be a good place to post this article about flying to Tehachapi this summer, as this forum seems to get more traffic than the Events/Fly-In's. Maybe some of you with a lot of high (for a 170) altitude operating experience will put in your $0.02 worth. If nothiing else, all of you will know how to pronounce Tehachapi before you get here this summer.

Miles

_____________________________________________

Let’s Fly to Tehachapi (Tah-HATCH-ah-pee)
By
Don Harrell

What is the best route? It actually depends on hour definition of “best”. If you are comfortable on direct routes up to 11,000 feet, over some desolate territory, and rough terrain, then you will be able to save a few minutes. Personally I prefer to use the lowest passes, fly down valleys looking up at the peaks, and follow roads or railroads. In other words staying low and close to some form of civilization just in case. My suggested routes to Tehachapi will follow this thesis but there are many equally easily flown ones.

Here are some things to remember on the way:

Hypoxia. We older folks are more subject to hypoxia than we used to be. It is a sneaky robbery of our mental processes. So subtle that some people refuse to admit that they can be or are affected, so read up on it. Some of the popular beliefs about how to determine its onset are not reliable!

Water. It is easy to become dehydrated out here in the hot summer. Carry at least four one-quart bottles of water. Two can be refilled and frozen each night and the others cached for emergency use. Don’t just carry it around, DRINK IT!

Density altitude. Learn how to use your E6B to compute density altitude. Both takeoffs and landings are affected, but we seldom talk about landings. The higher your altitude, the higher your touchdown speed at a given indicated airspeed. Your indicated approach airspeed should be he same at any density altitude, but the runway will be whizzing by faster at the higher density altitudes. Don’t let that confuse you. Be ready for rapid zigs and zags. Stay on the rudder pedals.

On takeoff do not try to force it off. Let her run. Most high altitude airports have runways long enough to get airborne easily. It is the rate of climb you have to worry about once you get out of ground effect. Rate of climb can easily drop to 100 feet per minute or less on a really hot day. In that mile and a half a lot of tall cactus plants, telephone wires, or communication towers can pop up in your windshield. Plan ahead.

Don’t let any of these ramblings deter you from the trip. But please do keep them in mind. If you can spare a few hours, think of stopping at a high airport on a hot day and taking an hour of dual. It might eliminate a lot of nervous tension.

Some specific routes for your consideration will be described in the coming months. I am planning on describing rather detailed routes with what I call “entry points” at El Paso, Albuquerque, and Cheyenne. Let me know if you think a route further north will be useful. Come out one way and return a different way for more enjoyment. Have a good flight. Please feel free to call me if you want to discuss the trip. My number is in the directory.

Don Harrell

[Harold Holiman]

Don,

A straight line flight from here, north Georgia, to Tehachapi generally follows the route of old Route 66/I-40 from Oklahoma City to Barstow then highway 58 from Barstow to Tehechapi. I have not yet purchased charts for the trip. What is the elevation of the passes along this route and is the I-40/hwy 58 a good route to Tehachapi? Also, as I have stated on the thread in the Events/FlyIns section, I am looking for suggestions on interesting stops along old Route 66 as I have never been there before.

Harold H
Mbr #893
N92CP

[Mike Smith]

I flew my C-170A (stock engine) to OSH and back this summer. I went into and out of some high altitude airports, as high 5586'msl (Lander, WY) for example. I flew over the Sierra Nevada's in CA-NV and the Rockies/Continental Divide. All that to say ... it's do-able.

After that trip I am a believer in the advice I was given to keep the gross weight about 200 pounds below the certified max gross weight. I always took off with one notch of flaps (the "A" model flaps) and then retracted them shortly after liftoff and with a positive acceleration/climb rate. This gave me the book numbers for take-off performance (although the book says it's with no-flaps). The no-flap take-off roll seemed excessive, that's why I went to a little flaps. I felt like this got me off the runway in an adequate amount of time (don't yank it off!, let it "fly off" when it's ready).

On approach into the airport, I did a very good "birds eye view" of the airport area before landing. This helped me plan my departure "escape/climb" route in the event I need to force land (engine failure on T/O) or the climb rate was even more anemic than I planned on (Operator error/read wrong performance line). I only had to use this once, when I took off out of Lander. Even though I took off at 6am, the density altitude was somewhere around 7000' (if I remember correctly). I had figured the climb rate might be around 100-150 fpm, it was 50-150 for a while, but I had a nice level area picked out to make wide circling turns for gaining altitude before proceding on course towards climbing terrain.

Anyway, knowledge is power and there is no substitute for planning and preparation. I totally agree with Don Harrell that the terrain is not insurmountable, but you need to plan for it and have a higher awareness of the airplane's performance (or lack there of).

Cheers and have a great flight!!!

[Harold Holiman]

Someone on the Skywagon forum referred me to an article in the "Southwest Aviator" about flying along Route 66. For those interested the article is found at: http://www.swaviator.com/html/issueMJ03 ... 65603.html

Harold H
N92CP

[GAHorn]

The use of flaps above 6,000 density altitudes will increase takeoff distance. Takeoff distance is the distance from brake-release to 50' AGL. If you use flaps at high density altitudes, you may observe a shorter takeoff ground roll...but you will experience a longer total takeoff distance to 50' because of excessive drag. Remember that to retract flaps prior to clearing obstacles is counterproductive, so a takeoff flap setting should be retained until obstacle clearance...then retract flaps.
Although it might psychologically seem advantageous to reduce the ground roll....it actually hurts the total takeoff distance to use flaps above 6K density altitudes. See the Owners Manual, Section V, and/or the AFM.

[Mike Smith]

I'll look into that and reconsider.

Thanks

[flyguy]

THE CHART FER TWENTY DEGEREES GIVES 67 MPH AND FER 0 (THATS ZERO DEGREES) FLAPS IS 76MPH. NAOW IFFN U GO 76 WITH 20 DEGREES IS THE DISTANCE TO A 50 FEET OBJEK CLARENCE CLOSTER ER FARTHER AWAY? NOW FER 6000 FEET AT ZERO DEGREES FARNHIGHT AN 20 DEGREES FLAPS ITSA ONLEY A HUNNERT FEET FARTHER BUT AT SIX THOUSAN FEET AN ZERO DEGREES FLAPS AN A SIXTY DEGREE FARRNHITE ITSA HUNNERT SIXTY FEET. THEM BOOK RITERS WENT ON TO TELL ABOUT A HUNNERT DEGREES OAT! BUT I LOST INTREST!!! ITSA GONNA GIT MORE COMPLYCATED NOW CAUSE THE BOOK SEZ- GROUN RUN ISA 38 PERCENT FER TWENNY DEGREED FLAPS AN 40% FER NO FLAPS SO WHAR DO U MESHURE TIRE DRAG FRUM - START OF TAKEOFF ROLL - - ER WHEELS OFF(UP) THU RUNNYWAY ????? ARE WE CORNFUSED YET???? MA BESS BET--- GIT OFF THU GROUN KWIKER AN DOANT USE TOO SHARP A TURNS TU DOGE THU TREES ER ROKS THATS A POKIN UP NEAR WHERE URE HEADIN! AN DOAN'T WORRY BOUT TAKIN FLAPS OFF TILL WAY ABOVE EENY THING HARD.

[Dave Clark]

OK so what's the consensus on after the wheels leave the ground? I've found the best (for stock engine) is to level it in ground effect and build about 80 mph before initiating a climb. At high density altitudes it seems without doing that you can wallow along the runway nose up without climbing until you run out of options.

[Mike Smith]

Shortly after I'm safely airborne, I retract the flaps and accelerate to best rate of climb. If it's a cross country leg, I fly this speed till 1500'-3000' agl (depending on terrain), then I let it accelerate to 90-100 mph (for a better ground speed) and use this as my cruise-climb speed till level-off.

[GAHorn]

Flyguy....you sure took a simple subject and muddied the water.
It's a simple matter. Firstly, I never mentioned anything about 10 degrees of flaps. So don't confuse the issue by you bringing up your 52 model ....(the one that sits out front of your house and uses no runway at all!)
Secondly, my previous msg talked about density altitude. The Owner's Manual doesn't. It talks about atmospheric conditions. (It is using actual altitude and temperatures in it's calculations to arrive at an unspoken density altitude.) But you can get a quick understanding of the density altitude correlation if you look at the book's data on 60 degrees F. (Standard atmosphere is 59 degrees....and I don't think anyone's thermometer is more than 1 degree accurate.) It boils down to a density altitude of more than 6000' will adversely affect a takeoff with flaps of any setting. (Use your E6-B or other gizmo to enter the pressure altitude and OAT to arrive at density altitude. )
And I already answered your question about the wheel rolling distances. The takeoff distance is from brake release to 50' AGL.

The reason for different climb speeds (dependant upon flap setting) is to correct for drag vs coefficient of lift at that flap setting. The best angle of climb flaps extended is 67 mph and flaps retracted is 76 mph.
While it may psychologically seem advantageous to retract flaps after liftoff/before obstacles ....in actual fact the loss of lift will penalize your climb towards the obstacle. In other words, the benefit you gained in shorter ground roll with flaps is more than offset by the loss of distance/altitude in obtaining flaps up climb speed. The airplane will use less distance to clear the obstacle if flaps are left extended until after obstacle clearance. THEN raise flaps and let the airplane accelerate ...where no penalty exists from obstacle impact.
If one uses flaps for takeoff roll and then raise them prior to obstacle clearance...the total takeoff distance will actually exceed even that of a zero flap takeoff. Not good if obstacle clearance is a factor.
The best time to decide on flap useage is before brake release. Once the data is obtained, stick with the decision.
See the charts in Section V, Operational Data for the temps/altitudes which determine whether flaps should be used or not.

[flyguy]

I FIGGER HOW HIGH THE PLANE THINKS IT ARE THEN IFFN I DECREASE THE TIME IMA ROLLIN ONNA GROUN AND GIT UP FLYIN - ITS BETTER THAN WAITIN FER SPEED TU GIT HI ENOUF TU FLY WITH OUT FLAPS - - - THE FIRST CHOICE IS BETTER THAN THE SECUNT CHOICE.

IMA JEST SAYIN FLAPS HELP AN THATS THAT. TRY IT SUM TIME. IFFN U LOWER THE FLAPS A LITTLE BITTY BIT TU SIT MORE BETTER INNA SHADE ITSA LITTLE COOLER THAN IFFN YU LET THE SUN SHINE ON YER BAK AN YER BEER DOANT GIT HOT TO QUICK. SO IFFN I SIT INNA SHADE OF MY '52 FLAPS AN FIGGER WHAT THE DENSITY ALLYTUDE IS - - THEN INA LITTLE BIT ITTLE BE DARK AN I CAN GO UP AN SIT ONNA PORCH ?

I JES GOTS TU MUDY U THU WATER SUME ER YOULL GIT TOO MORE UPPITY!

[GAHorn]

I didn't decree anything, I just simplified Cessna's calculations. Their chart calculates the density altitude by causing you to enter the elevation and OAT...exactly the same way you do it with an E6-B. The reason I used the "density altitude" statement is because 1). it reaches the exact same answer/conclusion and 2). you don't need the Cessna chart in front of you to know if you should use flaps or not. You can simply commit 6K to memory. (In other words GAR, the Cessna charts have their shaded flaps-warning at all those conditions where the density altitude is more than 6K. Quit being argumentive and pull out your E6-B and check it out.)
The bottom line is still: density altitudes above 6K--- flap use will increase takeoff distance. (And raising the flaps before obstacle clearance will make matters even worse because you'll sink towards the obstacle due to the loss of lift when you raised them, AND you must now accelerate to a higher airspeed for best climb speed/flaps up.)

[Harold Holiman]

For those who are interested in nostalgic stops flying along old Route 66 in route to the convention, I have found a couple. Elk City, OK (ELK), has; Historic Route 66 Museum and convenient motels. Kingman, AZ (IGM), has; longest remaining section of old Route 66, Historic Route 66 Museum, Army Air Corp. Museum, and convient motels. Any other suggestions appreciated.

Harold H
N92CP
Mbr#893

[Harold Holiman]

Are there any natural hot springs around Caliente, CA , or any other place close to Tehachapi, that are open to the public? Also are there any airstrips near these springs or do you have to drive in to them?

Harold H

[Harold Holiman]

It is less than three and a half months to Tehachapi. Isn't anyone ready to start talking about the trip there yet on this board? It's a long way there from Georgia

Harold
Mbr#893