Takeoff and landing performance testing

[Draker]

Pretty much the only test I did not perform during my Phase I testing was to verify/measure takeoff and landing performance numbers. I'd like to finally correct this. Looking for any techniques/hints from others who have taken a complete, thorough look at their airplane's takeoff and landing distance performance.

The EAA flight test manual describes their method of measuring takeoff and landing distances, but it involves having some poor soul running around on airport grounds with wooden stakes and tape measures--ugh, has anyone come up with a better way?

Also about proficiency: I can definitely hit a landing point within the practical test standard of 400 feet and 1.3 VSO, +10/-5 knots, but in order to collect usable, repeatable data, I'd need to be much more precise. Not sure I can. Worth it to hire a test pilot who can be more consistent and precise?

Additionally, if you do manage to get good, repeatable data, it's only good for that one runway's slope, with that day's wind and density altitude. I suppose you could use some formulas to generalize test findings into general plots like you'd find in a certified aircraft's manuals. I enjoyed Ed Kolano's 2000-2002 series of Sport Aviation articles about flight testing, particularly the ones where he crunches the numbers afterwards to extrapolate the airplane's performance under conditions not tested. Unfortunately I don't think he wrote anything about crunching takeoff and landing performance numbers, which is too bad.

Am I overthinking this again? What did you guys do?

 

[plehrke]

The EAA flight test manual describes their method of measuring takeoff and landing distances, but it involves having some poor soul running around on airport grounds with wooden stakes and tape measures--ugh, has anyone come up with a better way?

I used my recorded flight data from gps to measure takeoff distance and landing roll. Maybe not real accurate but accurate enough. Takeoff distance from zero airspeed to increase in altitude. Reverse that for landing distance.

 

[Ironflight]

Couple thoughts:

1) yes, if you want accurate, repeatable data, the pilot has to be proficient enough to nail the touchdown point very accurately. Since RV’s take a thousand feet or so to land and stop (or less), a 200’ error is huge. But….since ti is YOUR airplane and the data you’re collecting is for YOUR use, and argument can be made that if you routinely use “X” amount of runway to land and stop, then it is useful information for your operations.
2) Worth it to hire a test pilot? In my opinion, no - Van’s already has data on roughly how much runway you need based on your testing, and unless you have a radically different configuration for your airframe or engine, then the factory data is probably as good as it is for a Cessna.
3) Measuring techniques - don’t forget Google Earth - if you have landmarks on teh runway that you can use, take pictures or remember (and write down) how many runway stripes you used, or that you were one stripe beyond taxiway “X”, then go to your computer and use the measurement feature on the picture of your runway. It is amazingly accurate.
4) Do your testing at sunrise for no wind (assuming it is a calm morning) and fly to a runway with no slope.

Paul

 

[SPX]

It won't be perfect, but ... If you use ForeFlight, and have it paired with some sort of position/GPS input, you will be able to open a tracklog, and based off of the groundspeed and altitude shown, you should be able to determine your takeoff & landing distances.

 

[David Paule]

Perhaps you could station someone off to the side of the runway a fair distaince from it and take photos or videos your landings. Since you know the runway light spacing, you should be able to scale the landing or take off distance from that.

It would still be a bit of a statistical thing, though, so the more landings and take offs you make, the better.

Just an idea.

Dave.

 

[PhatRV]

My Test Program

I am not going to follow the EAA test card for this portion of the test. My goal is test my skills at landing with a gradual stop without burning out the brakes. I am not looking for the shortest distance, but rather the comfortable distance plus margin so that I know the runway length I can land if I haven't landed at an airport before. The same with take off distance. I want to be able to take off with a gradual application of the throttle with a 50 foot clearance and I can lift off before 1/2 runway length, instead of the maximum performance shortfield take off technique. The combination of my take off and landing performance will allow me to know the minimum runway length I can operate safely. It is definitely far short of the performance of what the plane is designed for, with an expert pilot behind the control. I am going to use the foreflight data to determine the distances.

 

[nilberg]

Why not use a camera in the tail pointed to the landing wheels.
I did this in my Grumman AA-5A establish the safety factor to be used for the numbers in the POH.

I used the runway markings and other known features to establish adjusted numbers.

 

[rockwoodrv9]

You have to watch out for the house on the top of Sudbury coming into the south! Cameron Park isn’t the easiest for trying to target land and measure. I’m interested in the numbers you come up with but maybe try it at Mather!

 

[Draker]

Thanks for the great tips. I think this is enough to put a plan together.

I used my recorded flight data from gps to measure takeoff distance and landing roll.

G3X-recorded data would be good to sanity check my results with. WAAS GPS is accurate to (best case) around 2 meters which is pretty good, but the EFIS--logged data is sampled at 1/sec which is actually pretty coarse.

3) Measuring techniques - don’t forget Google Earth - if you have landmarks on teh runway that you can use, take pictures or remember (and write down) how many runway stripes you used, or that you were one stripe beyond taxiway “X”, then go to your computer and use the measurement feature on the picture of your runway. It is amazingly accurate.
4) Do your testing at sunrise for no wind (assuming it is a calm morning) and fly to a runway with no slope.

This is good too, look for a runway that has some nice visual references that you can see from an online map.

Why not use a camera in the tail pointed to the landing wheels.

Awesome. I even already have a camera mount that points at the wheels. Should have thought of that!

Cameron Park isn’t the easiest for trying to target land and measure. I’m interested in the numbers you come up with but maybe try it at Mather!

It's also sloped at both sides, not a good choice. I'm planning on doing the testing closer to sea level at a flat as a pancake runway.

 

[Scott Hersha]

This might be a good use of the EAA additional pilot program for Phase 1. Go to an airport within your flight test area with standard airport runway markings, along with an additional pilot (trained) in your other seat. Runway painted markings should have standard spacing, and edge lights are normally spaced 200’, but check with the airport in use to make sure. You fly the airplane to the best of your ability, and let your additional trained pilot record distances based on his/her observance of runway markings/edge light spacing. Try to do this as close to gross weight as you can. Your result should be the average of several attempts (4-5). You can do this for both takeoff and landing on a single circuit to a full stop landing. If you want, you can repeat these tests at a very light weight, but the near gross weight test is most important.

 

[Draker]

Related, will (at least not-busy) towered airports be OK with you briefly coming to a full stop on the runway before taxiing off? I've never actually asked for that, and wouldn't even know the phraseology to use to request such a landing. "Full stop" just means roll out of the landing onto a taxiway.

 

[SPX]

Related, will (at least not-busy) towered airports be OK with you briefly coming to a full stop on the runway before taxiing off? I've never actually asked for that, and wouldn't even know the phraseology to use to request such a landing. "Full stop" just means roll out of the landing onto a taxiway.

Ask for a "Stop & Go"

 

[airguy]

Find somebody with a dirt/turf private strip nearby that will let you paint or chalk distance marks on the runway, to use for measurement.

 

[RV8JD]

G3X-recorded data would be good to sanity check my results with. WAAS GPS is accurate to (best case) around 2 meters which is pretty good, but the EFIS--logged data is sampled at 1/sec which is actually pretty coarse.

The Dynon SkyView system can record data as frequently as 16 times per second or as infrequently as once every 10 seconds, with the record rate chosen by the user. Doesn't the G3X system allow the user a choice of recording intervals?

 

[planenutz]

I did it the old fashioned way - I had a friend standing on the side of the runway with a distance measuring wheel. Got measurements accurate to within a couple of feet. The testing was carried out on a zero wind day with 50% fuel.

Of course it helps when you have a friendly airport to work with.

 

[rv8ch]

The Dynon SkyView system can record data as frequently as 16 times per second or as infrequently as once every 10 seconds, with the record rate chosen by the user. Doesn't the G3X system allow the user a choice of recording intervals?

Same with the GRT - I'll bet it's possible in the Garmin. If not, your phone with an app like foreflight or cloudahoy will sample frequently enough to get you good numbers.

BTW, when I did my testing it was all done at MTOW. Having a heavy sidekick will help avoid having to load up the aircraft with too many water bottles or lead shot.

 

[Scott Hersha]

Related, will (at least not-busy) towered airports be OK with you briefly coming to a full stop on the runway before taxiing off? I've never actually asked for that, and wouldn't even know the phraseology to use to request such a landing. "Full stop" just means roll out of the landing onto a taxiway.

I don’t think the tower would mind, as long as the pattern isn’t busy. You’ll only come to a stop momentarily to make note of distance used, and then taxi clear of the runway. I think it’s a good idea to call the tower on the phone before hand and tell them what you want to do.

 

[Roadjunkie1]

Take off and landing distance measuring....

I did it the old fashioned way - I had a friend standing on the side of the runway with a distance measuring wheel. Got measurements accurate to within a couple of feet. The testing was carried out on a zero wind day with 50% fuel. Of course it helps when you have a friendly airport to work with.

This is kind of what I did. The numbers do not have to be exact unless you are THAT OCD! Even pacing off what the distance is will give you a general idea of what the distances are. I live at an airpark so it was easy to have the distances marked off by someone standing in the ditch at the side of the runway. A bag of cheap flour can be your marker powder! I did mine on different days with different weights and plotted that on a chart to come up with an average of the distance it would likely take under variable circumstances. Again, there are many variables that will change your results. Your data will give you an idea of what your airplane will do which is, really, what the test flying is for. Is your airplane rigged such that it won't do what the testing from Van's did? That is what you need to find out.

I have no idea how far in actual feet the Cub will use to take off from a stubble field or other unimproved landing spot but if I pace off 100 paces (~300 feet) and mark where that is, I will typically be off the ground before that. Would it be fun to know in actual feet? Oh, yeah, I suppose. But for practical flying, knowing it was actually 289 feet: not needed. I also know that if I challenge a 150 hp Super Cub to a STO challenge, I will walk away with the $5 bet. Unless he was so put off he wouldn't pay up.....which he didn't......

 

[lr172]

Couple thoughts:

1) yes, if you want accurate, repeatable data, the pilot has to be proficient enough to nail the touchdown point very accurately. Since RV’s take a thousand feet or so to land and stop (or less), a 200’ error is huge. But….since ti is YOUR airplane and the data you’re collecting is for YOUR use, and argument can be made that if you routinely use “X” amount of runway to land and stop, then it is useful information for your operations.
2) Worth it to hire a test pilot? In my opinion, no - Van’s already has data on roughly how much runway you need based on your testing, and unless you have a radically different configuration for your airframe or engine, then the factory data is probably as good as it is for a Cessna.
3) Measuring techniques - don’t forget Google Earth - if you have landmarks on teh runway that you can use, take pictures or remember (and write down) how many runway stripes you used, or that you were one stripe beyond taxiway “X”, then go to your computer and use the measurement feature on the picture of your runway. It is amazingly accurate.
4) Do your testing at sunrise for no wind (assuming it is a calm morning) and fly to a runway with no slope.

Paul

I follow a similar approach. My runway is 3800' long with three approx equidistant turn offs, therefore segmented into 950" areas. I rarely go past the 1/2 point (nasty x wind days are an exception as I carry more speed) and usually end up midway between the 1st and 2nd and just coast to the mid point without too much braking. Therefore, I just don't go to runways less than 1800' Don't think this has ever been a limiting factor for me. Someday I may make an effort to learn the skill to consistently land and get off at the first intersection without a big headwind, but it really hasn't been a limiter for me.

The real thing to watch and train for is the obstacles. I have gone to several airports with 2-2500' runways with 150' trees at each end. However, I am pretty comfortable with steep approaches, but know many are not. Lots of folks that haven't slipped all the way into a landing since their checkride. This is worth practicing IMHO. I see these guys flying 2 mile finals and wonder to myself what would they do at a 2000' strip with tall trees at the end, as the FAA's 3.5 degree thing goes out the window in that case.

I needed a TO and landing chart for the 6 for my son's checkride. I just took the published data from Vans and added 20% to account for the fact that neither my son and I are test pilots and will likely NEVER be able to land the 6 at the minimum. I then used some math and a Koch chart to produce the temp and altitude extrapolation. I have used the 950' intersection to valid these numbers on warm day take off's to be sure that the chart was close to reality. You can also go to a larger class D airport to do some of this, as many have runway distance signs that are exactly 1000' apart. The AFD charts have accurate distances between intersections for larger airports and the towers will typically grant intersection takeoffs from wherever you want, as long as you request it.

Larry

 

[rocketman1988]

Comms

I don’t think the tower would mind, as long as the pattern isn’t busy. You’ll only come to a stop momentarily to make note of distance used, and then taxi clear of the runway. I think it’s a good idea to call the tower on the phone before hand and tell them what you want to do.

If there is a tower in operation, and you plan on stopping on the runway, it is always better to communicate your intentions with the tower; it may save you a phone call after the fact.

All it takes is a "Request stop and go" to communicate this, then everyone is on the same page.

In one case, I was able to listen in on that phone call. Interesting to hear what the tower is expecting during a landing...here is a short summary:

Cleared to land - expecting a rolling exit of the runway

Cleared for touch and go - expecting a landing followed by a rolling takeoff

Cleared for the option - expecting either a rolling exit OR a touch and go

Cleared for stop and go - expecting a landing to a full stop on the runway followed by a takeoff

It has been my experience that a simple communication, keeping everyone informed of your intentions, has the most favorable outcome...

 

[Marlonyoung]

Centerline stripe

The centerline stripe is 120 feet long and 36 inches wide. The gaps between each stripe are 80 feet.

 

[lr172]

I

Cleared for the option - expecting either a rolling exit OR a touch and go

..

One day I was doing t&g's with my son. I was cleared for the option. On base, I requested a stop & go. Tower replied, I already cleared you for the option and that includes s&g. At least in that controller's mind, the option seemed to appliy to anything I wanted. Unclear what the actual protocol is. Frankly, I wan't sure and felt it was best to request just in case. I do occasionally get cleared for t&g and not the option.

Larry

 

[Roadjunkie1]

Tower staff.....

One day I was doing t&g's with my son. I was cleared for the option. On base, I requested a stop & go. Tower replied, I already cleared you for the option and that includes s&g. At least in that controller's mind, the option seemed to appliy to anything I wanted. Unclear what the actual protocol is. Frankly, I wan't sure and felt it was best to request just in case. I do occasionally get cleared for t&g and not the option.
Larry

Better reply would have been: Roger that, 25Echo. You are cleared for a stop and go 36L as requested. He surely must have known he was dealing with a novice pilot and being a snot-*** on the radio only discourages people from asking for what they need. Or staying clear of tower-operated fields..... You did the right thing by clarifying the instructions he gave you. If you aren't sure, ask.....Mr Big Pants Tower Controller......

 

[lr172]

Better reply would have been: Roger that, 25Echo. You are cleared for a stop and go 36L as requested. He surely must have known he was dealing with a novice pilot and being a snot-*** on the radio only discourages people from asking for what they need. Or staying clear of tower-operated fields..... You did the right thing by clarifying the instructions he gave you. If you aren't sure, ask.....Mr Big Pants Tower Controller......

To be clear, this controller made that statement with absolutely no attitude. I got the sense he was trying to educate vs talking down to me,which I appreciated. I only mentioned it to clarify the statement Bob made that didn't mesh with my experience.

Now, another time I was flying IFR into DEN bravo airspace. In Chicago airspace, they always clear me into the bravo, even on an IFR flight plan, so assumed it was required as it is when VFR and I had never flown IFR near a bravo except Chicago. So, I am 5 miles from hitting the Bravo, so call up and tell them just a reminder that if I stay at my altitude I am going to hit the bravo in a minute or two. THAT guy comes back with a really bad attitude and yells at me for making the statement as I was on an IFR plan and didn't need the clearance. I was like WOW, I am just trying to be safe, keep everyone happy and keep my license. All it required was 2 seconds to say cleared or even clearance not necessary to educate me. Instead he wasted 15 seconds dressing me down. I remember telling my wife "What an a$$! That wasn't called for" It just didn't seem like a stupid request from a student pilot and I can't imagine that I was the first GA pilot to not be sure of the regs regarding bravo airspace, as the FAA has us scared to death to go near them. In fact we had a student pilot out doing training at 3500 under the 4000 Bravo shelf. When he landed, he got a call from ATC asking what he was doing. They told him he needs to stay further away from the Bravo as he was interfering with Ohare traffic.

 

[BobTurner]

Pilots and controllers are both humans, sometimes they get frustrated. I’d suggest that sometimes a little tact can clarify things in a polite way. e.g.’ATC: cleared for the option 25 right’; RV:’cleared for the option 25 right, expect stop and go.’ But if unsure, always ask.

 

[Traash]

As a starting point, you can use Vans numbers and adjust for DA using an online interactive KOCH chart calculator. Assume Vans are at gross weight, standard day sea level, no wind/no slope, hard surface.

Record the numbers (TO distance and fpm converted to ft/NM) for 1,000' increments to be referenced prior to takeoff. Reference existing DA and interpolate as necessary.

I found the takeoff distance numbers to be very accurate from 0-10K DA. The calculated climb performance is lower than actual.

G3X provides a climb gradient readout (ft/NM) which is what you really need for IFR obstacle clearance.


https://www.takeofflanding.com/

 

[Desert Rat]

Related, will (at least not-busy) towered airports be OK with you briefly coming to a full stop on the runway before taxiing off? I've never actually asked for that, and wouldn't even know the phraseology to use to request such a landing. "Full stop" just means roll out of the landing onto a taxiway.

The magic words you seek are "stop and go" or "cleared for the option"

Edit; I just read through some of the replies and it seems like there's some confusion on what it means to be cleared for the option. Here's the definition from the pilot/controller glossary:

CLEARED FOR THE OPTION- ATC authorization for an aircraft to make a touch-and-go, low approach, missed approach, stop and go, or full stop landing at the discretion of the pilot. It is normally used in training so that an instructor can evaluate a student's performance under changing situations. Pilots should advise ATC if they decide to remain on the runway, of any delay in their stop and go, delay clearing the runway, or are unable to comply with the instruction(s).

 

[rolivi]

Related, will (at least not-busy) towered airports be OK with you briefly coming to a full stop on the runway before taxiing off? I've never actually asked for that, and wouldn't even know the phraseology to use to request such a landing. "Full stop" just means roll out of the landing onto a taxiway.

I can't say I've done a S&G as my LAST landing. Usually for the last one I tell them this will be full stop and back to parking. But I prefer S&G to T&G because with touches I don't always slow down enough to need all the right rudder I do from a stop.

Now, that's for landing practice. For take off you can/should advise tower you'll need some extta time on the runway. This is so you can line up, full brake, power up, and get a realistic short field take off. They (sorta) know what your doing and it is not an unusual reqquest.

 

[Squid]

For what it's worth, I use two rough methods of T/O & Landing measures:
- I import the flight path recorded in Foreflight to Google Earth and then look at it from the side to give me a rough approximation of when I broke ground on takeoff. For landings I look at it from the top to see where I turned off the grass field.
- On occasion I will import the EFIS data to Excel and try to nail down the lat/long where I show positive climb and vertical acceleration. I then use a lat/long calculator online to measure the actual distance. That works for takeoff. My EFIS samples only once/second so the calculations are rough, but good enough to get a sense of takeoff distance.