carusoam Posted August 26, 2020 Report Posted August 26, 2020 For such a precision discussion... Since we are talking feet of accuracy... You really want to pay attention to each detail typed... 55% rh is a pretty dry day... Isn’t it? Using a 2k’ runway is great, until one unknown gets in the way... My favorite runway is a 2.2k’ runway... not a lot of room to get shut down if the engine stumbles... on rotation... Off the ground, getting the gear cleaned up...and the trees are growing larger in the windshield... I like to have this practiced a few times... long before going to that runway... With a family of four it gets really important... Plan for the go-around... I use CloudAhoy attached to a portable waas source... to collect data.... my WAAS source is an ancient SkyRadar ADSB in device... If you are not using WAAS data, you won’t be collecting distance in feet.... it may be +/- 100 yards or worse... but it will give answers out to two decimal points... precise yet inaccurate... Trying to determine T/O distance by looking out the window... is old school inaccurate.... Patrick always reminds us to use the entire runway, and proper procedures, when the trees are visible... Knowing the DA is critical. Best regards, -a- 1 Quote
steingar Posted August 26, 2020 Report Posted August 26, 2020 I usually take off with a couple pumps of flaps. I wrench the airplane into its rotation at 60, usually wheels up by the time I hit 80. Any question and the gear is coming up quick. It's your biggest source of drag. Quote
Pilot boy Posted August 26, 2020 Author Report Posted August 26, 2020 On 8/26/2020 at 5:07 PM, pmccand said: All this discussion and no one mentions a Koch chart?!! You don’t need ANYTHING in the POH describing take off data as long as you have your pressure altitude and temperature. This chart works for ANY aircraft. So, estimating pressure altitude for a 1,450 MSL airport at 95 deg F day, your takeoff distance increases 1.5x, and rate of climb drops by 0.65. Given your report of 2,500 feet needed for takeoff is not far off the calculated number, and worse, your climb rate should drop from around 850 fpm to 520 fpm. Expand Thanks for posting this, I'm going to print this off and use it in the future. I also wanted to update everyone, as I googled last night I found a way to export KLM files from Foreflight into Google Earth. This enabled me to see fairly exact distances, speeds, etc. The ground roll was not as bad as I had thought...I think the end of the runway just looked bigger in the window than I'm used to on the longer ones back in Omaha. Basically the Google earth KLM file showed a ground roll of between 1976 and 2286 ft (worst case - the data is not perfect in that I think it extrapolates between reporting points). Overall it appears that I took off right around 2000 to 2100 ft, achieving about 50 ft AGL over the end of the runway at 91 mph. The remaining runway is indicating about 1000, or 1100 ft. I could have probably rotated slighlty sooner to get into ground effect and retract the gear. I did retract fast but I was climbing out by then at Vx. Takeoff weight was 2376 lbs according to my supercomputer in Foreflight where I update meticulously. I probably did the right direction as the slope was at least around 2 percent almost the entire length of the runway, and for some of the runway it shows even greater (-2.5 percent) also the tailwind seemed largely blocked by trees as the windsock was totally flat at takeoff (could have still played a role hard to say). I appreciate the slope and tailwind calculations this poster included in the other post showing the percentages and how they worked against me. Quote
Pilot boy Posted August 26, 2020 Author Report Posted August 26, 2020 Here are some screenshots of the takeoff in Google Earth. Basically the Google earth KLM file showed a ground roll of between 1976 and 2286 ft (worst case - the data is not perfect in that I think it extrapolates between reporting points). Overall it appears that I took off right around 2000 to 2100 ft, achieving about 50 ft AGL over the end of the runway at 91 mph. The remaining runway is indicating about 1000, or 1100 ft. Quote
Pilot boy Posted August 26, 2020 Author Report Posted August 26, 2020 On 8/25/2020 at 11:32 PM, takair said: You can export to Google maps and might get a sense of what happened. It will even do 3D view, which is cool. I also think that cloudahoy (something like that) will work. Hit the “send” arrow for some options on exporting. Expand I read this after I found out about the KLM file export by googling on foreflight support - BUT - this did end up working very well. so great suggestion Quote
Pilot boy Posted August 29, 2020 Author Report Posted August 29, 2020 On 8/26/2020 at 2:50 PM, steingar said: I usually take off with a couple pumps of flaps. I wrench the airplane into its rotation at 60, usually wheels up by the time I hit 80. Any question and the gear is coming up quick. It's your biggest source of drag. Expand I don’t know that I’ve really taken the M20E off at 60 mph. You are able to lift it off that quickly or are you yanking pretty good to make that happen? Usually I rotate around 75 or 80 if I’m heavy. Quote
takair Posted August 29, 2020 Report Posted August 29, 2020 On 8/29/2020 at 5:36 PM, Pilot boy said: I don’t know that I’ve really taken the M20E off at 60 mph. You are able to lift it off that quickly or are you yanking pretty good to make that happen? Usually I rotate around 75 or 80 if I’m heavy. Expand I suspect he means he starts pulling at 60 to get the nose light....it becomes an almost continuous pull to rotation and liftoff... wind and field conditions may change that....especially crosswind. 1 Quote
carusoam Posted August 29, 2020 Report Posted August 29, 2020 Keep in mind... It takes a lot of typing to describe the T/O procedure... From the amount of force to lift the nose off the ground, to the amount of time that passes by... As far as the interpolation between points goes... It isn’t obvious in the google maps above... When using a non Waas source... there is often lots of straight lines with sharp angles over areas you know you didn't exactly fly over.... If your breadcrumbs show every wiggle while taxiing... and your T/O run is exactly next to the centerline the way you remember it.... You probably have WAAS enabled... PP thoughts only... Best regards, -a- Quote
Pilot boy Posted August 30, 2020 Author Report Posted August 30, 2020 On 8/29/2020 at 8:42 PM, carusoam said: Keep in mind... It takes a lot of typing to describe the T/O procedure... From the amount of force to lift the nose off the ground, to the amount of time that passes by... As far as the interpolation between points goes... It isn’t obvious in the google maps above... When using a non Waas source... there is often lots of straight lines with sharp angles over areas you know you didn't exactly fly over.... If your breadcrumbs show every wiggle while taxiing... and your T/O run is exactly next to the centerline the way you remember it.... You probably have WAAS enabled... PP thoughts only... Best regards, -a- Expand i think Google is interpolating between the data points the Sentry provided but Sentry I believe does use WAAS. I have a separate GPS with WAAS but the data is from Foreflight Sentry. It usually has me within 1 meter accuracy. The one thing it seems to lag a little is when accelerating down the runway, the speeds are a bit delayed during the takeoff roll so I don't trust the speed readout on takeoff it's giving me. Quote
Pilot boy Posted August 30, 2020 Author Report Posted August 30, 2020 On 8/29/2020 at 6:03 PM, takair said: I suspect he means he starts pulling at 60 to get the nose light....it becomes an almost continuous pull to rotation and liftoff... wind and field conditions may change that....especially crosswind. Expand I'm trying to rotate a little sooner now than I did especially when I'm by myself and kight...it depends on the weight I'm at. With me and the guy next to me almost at gross it was really not wanting to lift off before 80, but I'm not using alot of force just letting the plane decide when it wants to lift off. Quote
carusoam Posted August 30, 2020 Report Posted August 30, 2020 Pb, Expect that the display is averaging a bunch of data points to give a smooth read-out... The cost of smooth read-outs is the apparent delay... The data will be plenty accurate this way... after the fact... To know how Foreflight handles the data probably requires an inside contact, somebody we can send the question to... We had a similar discussion with Sies, the fuel level guys... so much data, that averaging makes sense... Just a bit harder to use in real time... I have one Older portable WAAS resource from Garmin. It only gets one piece of data every second or two... If I were to average 10 data points... I can go from zero to almost flying in that amount of time... Best regards, -a- Quote
Ibra Posted August 30, 2020 Report Posted August 30, 2020 (edited) On 8/26/2020 at 5:07 PM, pmccand said: This chart works for ANY aircraft. Expand It still assume normally aspirated aircraft (e.g. non-turbo) and 16kft ceiling but the multiplicative factors are still very good for "any NA aircraft type" as the difference between 2.5 and 3.0 ground roll or 0.2 and 0.0 climb rate is rather academic I have a knee board version printed ! Edited August 30, 2020 by Ibra Quote
gsxrpilot Posted August 30, 2020 Report Posted August 30, 2020 On 8/29/2020 at 8:42 PM, carusoam said: It takes a lot of typing to describe the T/O procedure... Expand 1 Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.