The idea is this deeper dive is supported by the shorter context videos. But it might be too confusing. Thanks for bearing with me as we figure this out, and glad you like the video.
When glider tow pilots come in to land with the tow line and there is a fence or tree line at the end of the runway they bump the elevator which whips the tow line up and over the obstacle. It's pretty neat to watch.
All of your videos are very good, thanks for all you do. Curious how you (or someone) ultimately decided on the location for the fuselage-mounted static ports on the Thorp T18. I have a T18 and find the Piper pitot/static mast is sub-optimal. Surveying various locations now for a better static source... Thanks again, Peter
Very interesting Elliot. I've been doing something similar with my pitot/static system on my Europa after changing the Pitot head for a new Dynon one. I've moved my static source to a couple of different locations. I've been using the heading method for the calibration. Input the various speeds into an excel spread sheet and the spread sheet gives me the tolerance
The GPS method is fantastic. The problem here was we were focused on stall speed, and I wasn't comfortable droning through a cloverleaf at 1.1 VS. I was also intimidated by the risks of building a quick and dirty trailing cone, so I am stoked to have been able to justify going through that process.
reminds me of watching test flights of the DC-9 Super 80 in Yuma, AZ (a long time ago). They used the trailing static line to get the true static pressure too. Of course, they weren't dragging meters of hose on the runway behind them. :-)
At 6:15 you discuss how the tube was pulled at the top of the rudder and say "I don't know if it was you guys pulling it off..." At 6:50 you can see "youse guys" pulling it off and it appears to me the tape on the rudder top looks like it was already pulled. They also clearly did not pull it. So - I don't think it was" youse guys...." Probably a bit of force on that cone during flight...
Thanks for the comment, great observation. These were the biggest risks with this program. While we can calculate the drag on the cone at a given speed in flight calculating the drag of the hose and cone on the ground is a bit tougher, and all the ground handling situations that could arise more so. I tried to include these details in the video as I found them missing from the documentation of similar testing oline. I am glad you found value there. Thanks again!
Oh man, i must've gone back and watched the victory laugh at least 6 or 8 times. Really enjoying your content, everything about it is fascinating. -A&P, IA, Airplane and Helicopter pilot.... always learning!
Elliot. Interesting way to remove the wing or fuselage and prop wash effect. I am flying with 2 independent P/S systems. Most of the time one reads about 4Kts lower but they very about +-6Kts so sometimes the highest airspeed swap. Small pitot alpha errors can easily create 5Kt error. I think this depends some what on cosine of the angle between pitot angle and airflow alpha. The error gets much worse at lower airspeed. The two airspeed indications usually converge as the airspeed goes higher. I have designed a ultrasonic Airspeed sensor that reads the sound travel time. Add the travel time front to back and back to front and divide by 2 and compute using speed of sound. Need to finish the US design and try it. Thanks for the video!
Its a short taildragger that lands relatively fast, so its a bit "quick" directionally right at touchdown. Not Pitts quick, but it'd be good to bring your A game.
Ok, so now you've identified the static problem. Whats the next step for this particular plane? I'm curious because I'm suspecting the same issue for my RV-7A. I am almost always showing a tailwind and a 44KIAS stall speed. Thanks for the videos, Elliot. Scott RV-7A
Depends on your goals. The right way to do it is to survey the pressure field around the airplane comparing locations to the "truth source" and looking for the position that has the lowest error. But that's a lot of work.
Great video, love your stuff. Did you completely bypass the aircrafts static system and just use the trailing cone assembly? Or was it plumbed into the original static source as well?
This is one of my favorite videos from you! I think your evil laugh of success perfectly describes the mad scientist that must be in every test pilot.
Thanks man. I wasn't sure about leaving that part in there.
It was cool to see.
Nicely done. Appreciate the longer video, gives a layman like myself time to wrap their head around what's going on. Thanks for all you do !
The idea is this deeper dive is supported by the shorter context videos. But it might be too confusing. Thanks for bearing with me as we figure this out, and glad you like the video.
When glider tow pilots come in to land with the tow line and there is a fence or tree line at the end of the runway they bump the elevator which whips the tow line up and over the obstacle. It's pretty neat to watch.
I'd like to see that
All of your videos are very good, thanks for all you do. Curious how you (or someone) ultimately decided on the location for the fuselage-mounted static ports on the Thorp T18. I have a T18 and find the Piper pitot/static mast is sub-optimal. Surveying various locations now for a better static source...
Thanks again,
Peter
Very interesting Elliot. I've been doing something similar with my pitot/static system on my Europa after changing the Pitot head for a new Dynon one. I've moved my static source to a couple of different locations. I've been using the heading method for the calibration. Input the various speeds into an excel spread sheet and the spread sheet gives me the tolerance
The GPS method is fantastic. The problem here was we were focused on stall speed, and I wasn't comfortable droning through a cloverleaf at 1.1 VS.
I was also intimidated by the risks of building a quick and dirty trailing cone, so I am stoked to have been able to justify going through that process.
reminds me of watching test flights of the DC-9 Super 80 in Yuma, AZ (a long time ago). They used the trailing static line to get the true static pressure too. Of course, they weren't dragging meters of hose on the runway behind them. :-)
Right on!!
At 6:15 you discuss how the tube was pulled at the top of the rudder and say "I don't know if it was you guys pulling it off..." At 6:50 you can see "youse guys" pulling it off and it appears to me the tape on the rudder top looks like it was already pulled. They also clearly did not pull it. So - I don't think it was" youse guys...." Probably a bit of force on that cone during flight...
Thanks for the comment, great observation. These were the biggest risks with this program. While we can calculate the drag on the cone at a given speed in flight calculating the drag of the hose and cone on the ground is a bit tougher, and all the ground handling situations that could arise more so. I tried to include these details in the video as I found them missing from the documentation of similar testing oline. I am glad you found value there. Thanks again!
Oh man, i must've gone back and watched the victory laugh at least 6 or 8 times.
Really enjoying your content, everything about it is fascinating.
-A&P, IA, Airplane and Helicopter pilot.... always learning!
Thanks man. It was a fun program.
Elliot. Interesting way to remove the wing or fuselage and prop wash effect. I am flying with 2 independent P/S systems. Most of the time one reads about 4Kts lower but they very about +-6Kts so sometimes the highest airspeed swap. Small pitot alpha errors can easily create 5Kt error. I think this depends some what on cosine of the angle between pitot angle and airflow alpha. The error gets much worse at lower airspeed. The two airspeed indications usually converge as the airspeed goes higher. I have designed a ultrasonic Airspeed sensor that reads the sound travel time. Add the travel time front to back and back to front and divide by 2 and compute using speed of sound. Need to finish the US design and try it. Thanks for the video!
Cool stuff, thank you for the comment.
Nice video! I love how you described exactly what was going on. Also, the "mad scientist" victory laugh was great
Thanks man
Great interesting video! I wasn't sure how you dealt with airspeed calibration. Now I know....
Thanks man!
Ah yes, the static cone. Our TD (an XP and USNTPS alum) demo'd one some time ago for us minions. Great video!!
Very cool! Thanks for the comment!!
That cackle when you realize you’ve figured it out. Stoke factor: high.
Twas a good day.
Awesome and informative video! And did see that correctly? Are those SkyCatcher seats?
Good eye!! They are, and they are totally awesome!!!!!
How would you describe flying/landing the T-18? Some have said the landings can be tricky due to coupled gear? Is this your personal a/c?
Its a short taildragger that lands relatively fast, so its a bit "quick" directionally right at touchdown. Not Pitts quick, but it'd be good to bring your A game.
Ok, so now you've identified the static problem. Whats the next step for this particular plane? I'm curious because I'm suspecting the same issue for my RV-7A. I am almost always showing a tailwind and a 44KIAS stall speed.
Thanks for the videos, Elliot.
Scott RV-7A
Depends on your goals. The right way to do it is to survey the pressure field around the airplane comparing locations to the "truth source" and looking for the position that has the lowest error. But that's a lot of work.
Great video, love your stuff. Did you completely bypass the aircrafts static system and just use the trailing cone assembly? Or was it plumbed into the original static source as well?
Awesome idea!
it was fun
Well that was clever!
Glad you dig it
Awesome! And really interesting, Thanks Elliot🔥
My pleasure!
Bad Ass Shit that Fly’s!🇺🇸👍
Truth!!!