Cherokee 6 gross takeoff technique?

JeffKing

I had a near tree encouter during takeoff at near gross on my Cherokee 6, 1970, PA32-260, and wanted to get some comments.

I took off a week ago from a 4000 foot strip with my whole family aboard, and barely cleared the trees. Was doing the numbers, 10 degrees flaps, rotate at 70, climb out at 95, and still got this. Field is at 1000 feet elevation, 60 degree temp. Had a stiff 80 degree crosswind however (15 knots).

On the way back, different field, same conditions, 3500 foot strip. Did a little better, no comments from the passengers about how close the trees where, but I let it run-up longer before letting go of the brakes, and held it down/advanced the numbers by 10mph before rotating/climbing.

I'm seeing full rich/full power fuel flow in the 26-28 gallon/hour range. At full power climb, the fuel pressure is going a bit below 1psi... still in green, but made me nervous. Electric pump seems to work and that was with it on. I had the RPM checked today at full throttle/full prop, and it was showing 2700rpm. 1500smoh and all compressions in the upper 70's, as of last annual 8 months ago.

And the other odd thing, is it had a respectable climb (500 feet minute) once I got up 500 feet or so. It was just near the ground the thing was dogging out.

Have all the knots2U mods (root, flap gap, hinge) and the Laminer Flow wing smoothing.

Assuming I don't have a mechnical issue, I'd like to see comments about taking one of these off at near gross. Ground run, and if the rotation/Vx/Vy speeds need to be at book or a little advanced.

thito01

On my Lance (PA32R-300), the short field takeoff is done at two notches of flaps, not one. It makes a big difference. I have been in several 2000' runways with no problems using two notches and standard short field methods. It takes 2000+ for just the ground roll when using one notch and normal takeoff methods.
Some (including me) do the full power, then release brakes, then at rotation speed add the flaps. (One advantage of manual flaps.)

JeffKing

Hmmm.... well I hadn't considered a 4000 foot runway short.. was more concerned about taking off at gross. Wouldn't using 20 degrees of flaps make things even worse at gross? (i.e. getting behind the power curve)

But thanks for the thoughts, I'll have to sandbag the aircraft to gross and see if indeed I can climb faster/at a steeper angle.

Oh, what is your fuel flow at full throttle?

thito01

Actually, I don't know my fuel flow at takeoff. I normally have everything to the firewall for takeoff. Although I lean aggressively during taxi, I have never had the need to lean for takeoff as I don't see density altitudes of 3000 or more MSL.

I fly mine at gross regularly as my family and full fuel only leaves me with 150# for luggage. I have three teenage girls and I have to weigh their bags before each trip or they will take their whole bathroom.

What is better than seat belts is to ask several student pilots if they want to see a real plane in action. They make great ballast.

Frank Norwitch

2 notches of flaps will allow you to rotate at 5-10 knots slower speed, hence you will get aloft quicker. Check your pOH for rotation speed using flaps. As Tony mentioned, some pilots like to put in a notch slowly just as you reach normal rotation speed. The plane will leap off the runway.

Frank.

jeroen

I regularly take off from a 600 meter runway in France at 1000 ft elevation at 30C at full gross with my T-tail turbo lance.
I let the engine and turbo spool up with the brakes on, then accelerate, no flaps, to 65 knots. Backpressure on the yoke, pull 2 notches of flaps and it lifts of within 3/4 of the runway. It took some guts to try it the first time, but works fine also with 15 knots crosswind.

thito01

So everybody does not have to do the conversion for Joroen's statement:
" Iregularly take off from a 600 meter runway in France at 1000 ft elevation at 30C at full gross with my T-tail turbo lance."

600 meter = 1 968.5 feet
30 degree Celsius = 86 degree Fahrenheit

I don't have the POH for my straight-tail Lance, but the ground roll in the books is about 1/4 lower for it when compared to the later t-tail.

Back to the original question. Yes, think of 4000' with trees as a 2-notch takeoff. You don't really need full short-field methods, but the 1-notch of flaps normal takeoff may not cut it at full gross. (As you have seen.)

JeffKing

OK, so the idea here then, as in a "short field", is to go for Vx (max angle) then once clear of the obstacle, clean it up for Vy?

Just a reminder though, this is a 260HP PA32-260.

Thanks for the thoughts. I'll give some of them a try.

JeffKing

I want to sincerely thank everyone on this tread. I bought 14 50lb bags of gravel (700lb total), my 250lb frame and a full load of gas, which put me within 50lb of gross and tried the techniques. Amazing difference. The popping 20 degrees of flaps got me at least 50 feet over the standard method. Also, holding that plane down in ground effect until at least 90mph made a huge difference, otherwise it wanted to climb out at 80-85 which as soon as it left ground effect had me mushing. The plane seems to have its Vx closer to 90mph then 95, but when I flew the family later in the day I held it at 95 to give me a litte more gust protection. No questions this time from the wife as to why the trees where so close!!

Tell you what, the 6 at full gross seems better then a 172 with me and my instructor in it, as far as climb/runway clearance.

thito01

Good job. Now you know why we suggested it. Major difference.

You will want an instructor and some altitude the first time you do a power-on, full-gross stall. It's not a bad stall, but it is different enough. Of course, the low-gross, power-on stall can really get the nose up.

With my straight tail Lance, I prefer to hold it on the runway until at least 80-90 if I have the runway. Then I get a good possitive rate right from the get-go so I can raise the gear at 20 feet without worry about settling. You might want to experiment with different rotation speeds for different runways.

Martin H

Art Madson has a short field technique that is a lot like the one Jeroen from the Netherlands mentioned. Perhaps that could help you if you need to LEAP off a field, at gross or not.
The technique is described in detail on the AMRD website, photo's included.
Jim C is far more familiar than I am with this, maybe he could weigh in.

Martin H

Jeff,

Did you ever get those VGs that you inquired about a few months ago? They should make a difference also to you, especially at gross.

thito01

After one trip to the maintenance shop, they left the quadrant friction lever loose. As I am rotating, things start to move and suddenly I have very little power.