Piper Dakota Pattern Speeds - New Owner / Student Pilot

BigBobVa

Good Evening! It is official. I pick up my 1st plane this week with my instructor. I am at 35 hours in an Arrow II, aced the written exam, and will finish getting ready for my PPL in a1979 Piper Dakota. Excited!

As I got ready, poured over the POH, and got all my ducks in a row, I wanted to see what speeds folks use in the pattern. The POH states Final Approach at 72 knots. I am guessing 90 Downwind, 82 Base, and 72 knots Final. Most of my training so far is in the Arrow II, so that is about what I am used to (only 100, 90, 80 in MPH). Abeam the runway in downwind, I am guessing drop to 15 - 17MP with full forward on the prop to get a good slope. I know the Dakota will be a little heavier in the nose and will probably use a little more trim than the Arrow II.

Any insights would be appreciated.

Thanks!

Bob

Scott Sherer

Congrats, Bob. In my Arrow III I'm about 85 to 90 kts in downwind depending upon other traffic. Base 80 to 85 and final 75 to 80.

swankaj

For normal approach, and rule of thumb, I use the 100 downwind, add flaps, reduce power and aim for 90 at abeam, then 85 in the base, 80 turning final, 75 short final no less than 70 over numbers and then adjust depending on if I am heavy or light.

In the terminal area I use 19MP 2200, or sometimes 17MP 2200. When the glide slope is intercepted, I throttle back to about 13MP which should get it to 2000 RPM with the prop full.

Theses settings match the other cherokees I have flown. 2000 RPM, notch of flaps, 90 kts.

swankaj

Here is the theoretical curve for velocity at max L/D (ie, Vy) in a clean configuration as function of total weight, scaling from 85 kts at 3000 lbs. I then use the same scaling for 1.3 Vso. I use about 3-4 kts in excess of 1.3 Vso for a little margin at landing, which also equates to an easy 3 kts per notch of flaps approx.

 

Scott Sherer

Oh Wow, very cool. Thanks for teaching me something today!

jacobsja

I am in the camp that this is more an academic discussion and best bets are to get with a CFI to hone the numbers.

Reasoning is that while the POH is an excellent guide, and getting inputs from the community will certainly help, each plane is a bit different due to things like rigging status, unique CG, and unique drag.

Secondary benefit of honing the numbers with a CFI is that somebody else is more easily able to take notes for correlation, and then getting this more experienced individual to help convert the numbers into a practice.

For a real-world example, when I worked through the current plane's learning curve, the CFI suggested to skip flaps 10* and go straight for flaps 25* on normal (ie: milder wind) approaches as it lessened the workload.

Another input I got from that CFI was to go to max RPM as part of final when MP was low. End result is that there is no noticeable change in actual RPM at that moment.

empannin

Bob,

Once you work out your numbers with your instructor that work best for you I would also suggest looking for opportunities to mix up your training and carry passengers if your CFI/insurance, etc allows.

The plane will perform differently closer to gross and having the first experience with a CFI in the seat is not a bad idea. The Dakota has a large useful load even with full fuel.

RobertSummers

Bob, Congrats on the Dakota! My flying partner and I bought a 1980 Dakota to do our training, primarily because our home airport is at 4850 MSL. So density altitude is always a concern. We are about to finish up and prepare for our checkride next month. The Dakota has been a perfect trainer for us.

Regarding speeds in the pattern, we strictly adhere to "Vmm" (minimum maneuvering speed) in the pattern. This is Vs1 x 1.404 or 65 KAIS x 1.404 = 91.26 rounded up to 92. Only after we turn base to final do we drop below Vmm to Vref, which is Vso x 1.3 or 56 KAIS x 1.3 = 72.8 rounded to 73. Similar to Vref, Vmm provides a 30% margin over over stall speed, but up to a 30% bank.

On departure, we do not turn crosswind (or turn out any direction) until, again, we have reached Vmm. Once we enter the downwind for landing, we reduce MP to 16" We have Vmm and Vref on our checklist, we brief these speeds before and during flight, and we have them marked on our airspeed gauge. Something else may get us, but its not going to be a stall spin in the pattern.

This concept of Vmm comes from our flight instructor Dan Gryder, and I encourage you to watch his youtube videos on this topic and AQP for GA. Let's talk more about our Dakotas! Good Luck. Robert.

T64Am22E35

Here in windy WY no slower than 85kias on base and looking for 70 - 75 on short final depending upon weight/wind gusts. When the wind is really blowing I use only one notch (10 deg) of flaps and no slower than 80 kias on final - again depending upon weight. Carb Heat ON for every landing is the way I operate the 0540.

Love the airplane!

empannin

Robert, thanks for sharing your technique. On approach I also make sure my turns are all descending and coordinated.

"Regarding speeds in the pattern, we strictly adhere to "Vmm" (minimum maneuvering speed) in the pattern. This is Vs1 x 1.404 or 65 KAIS x 1.404 = 91.26 rounded up to 92. Only after we turn base to final do we drop below Vmm to Vref, which is Vso x 1.3 or 56 KAIS x 1.3 = 72.8 rounded to 73. Similar to Vref, Vmm provides a 30% margin over over stall speed, but up to a 30% bank."

How do you account for weight differences in your speeds? For the Seneca III there is a 15 kt delta in stall speed as a function of gross weight from takeoff weight to empty. The old POH (now since revised) lists a barrier speed for the Seneca (over the fence) of 90 kts to 76kt from 4500 to 3000 lbs. I add 5 kts to this as I have a long runway. My useful load is ~ 1600 lbs and I usually fly using 1/2 to 1/3 of this with an over the fence speed of 85kts . I can really tell the difference at gross vs light with a large useful load.

FYI: The short field approach in a Seneca has barrier speeds of 82 to 68 kts and the same full flap config. This is coming in at a steeper angle with not much margin for bank. Also well below blue line and close to red line so in a twin this is a committed landing - you must land on engine failure short final vs an attempted go around. This is the exact scenario you will get eventually in a simulator. The instructor will set you up for a hot, high and heavy approach into a short runway. As soon as you are at Vref, gear and flaps full out on short final they will roll a virtual firetruck on to the field and cancel the landing clearance. The correct response is to declare an emergency and land on anything. An attempted go around will always be a crash because it is impossible no matter how fast you are on the controls. You are too low and too slow for a recovery. Most sim instructors will also pull stuff like this if you are coming in single engine and don't declare an emergency. Sorry for the thread creep!

BigBobVa

Thank you all so much! This is great information. Great idea to mark the gauges! After 20+ landings last week I have figured out my Dakota with 2 "non-FAA" (220lbs each) people, 95 in the downwind, 85 in base, and 75 full flaps in final seems to provide pretty consistent landings. In higher winds, using 25% flaps and 80 on the final seems comfortable as well. I am going to work with my CFI, get some cases of water, and load it up to 4 passengers' worth of weight, and try again.

Thanks!!

Bob

empannin

Great idea Bob, it is not hard light or loaded - just different. Always good to explore the full range for planes with higher useful load.

RobertSummers

Hi Eric thanks for the comments. Yes I should have said that all the turns at those speeds were to be coordinated and descending.

We account for the weight differences by assuming gross weights, thinking that this builds in some additional stall safety margin since we are always below. Also the POH Vso and Vs1 speeds underlying our computation are at GW. Robert.

PS BigBob I'd suggest you just stay above Vmm--92 KAIS--everywhere in the pattern until you have turned final. Then Vref +10/-5. Good Luck.

empannin

Hi Robert,

The trade off of assuming GW is the extra speed/longer runway roll out. For planes with large useful loads it does make sense to have different speeds. Could be a quick table for light fuel/pilot only, mid-weight and Gross Weight. I would leave all the downwind/base/final speeds the same as GW and only adjust the "over the fence" speed as a function of weight. This is consistent with the early POH's (at least for my Seneca)

kzadora

Robert, thank you for sharing the Vmm concept, sounds extremely useful.

Looking at your numbers though, they seem very conservative? The increase in stall speed at 30 degrees of bank, level flight, is only about 8 percent according to https://www.faasafety.gov/files/gslac/library/documents/2018/Nov/164492/P-8740-44.pdf Your calculations use a margin of over 40%, which corresponds to almost 60 degrees of bank, again, assuming level turn…

kzadora

Never mind, now I get it, it is 30% on top of level turn stall speed. Took a while but eventually I got it 😀