While my plane is down for annual, I've been doing some of my other passion, aerodynamic calculations, haha! Not typical for a Pitts lover I understand, but it's the plane I have and can do testing and comparing against the formulas as a fun mental exercise. It'll be some pretty "boring" test flying in this type of plane but I'm a curious guy.
To be valid and useful, all data has to be accurate of course. I'm aiming to make it as accurate as possible many ways. The plane is being weighed this annual (for the first time since it was built 43 years ago!). Will use accurate pilot weights and record everything during the flight(s). The aim is to calculate a drag polar by determining sink rate at 5 mph increments from 60 mph to 110 mph both with the prop in and prop out. I'll do repeated descents from 5,000' MSL to 3,000' MSL. That's 11 descents in each prop configuration. This seems like it will probably take around the 1.5 hrs of useful endurance and I'll factor in the slight weight change from fuel burn. Time and altitude will be recorded manually every 500' while my pilot friend does the flying as accurately as possible.
I've never seen any hard data on best glide speed, glide ratio, sink rate, etc... only "glides like a brick," "install lexan floor panels so you can see your engine out landing spot," etc. It's true that with the prop in, it does not glide well. With the prop out, it's quite respectable, being an aerobatic prop that goes to quite a high pitch. The manuals are not great having been produced so long ago. This will also produce a number for best range speed, speed for best endurance, and min sink speed (in case you have an engine failure over a decent spot and simply want to stay aloft for longer for troubleshooting and don't have to "get" somewhere.
Is there anything else y'all have been wondering but never tested?
To be valid and useful, all data has to be accurate of course. I'm aiming to make it as accurate as possible many ways. The plane is being weighed this annual (for the first time since it was built 43 years ago!). Will use accurate pilot weights and record everything during the flight(s). The aim is to calculate a drag polar by determining sink rate at 5 mph increments from 60 mph to 110 mph both with the prop in and prop out. I'll do repeated descents from 5,000' MSL to 3,000' MSL. That's 11 descents in each prop configuration. This seems like it will probably take around the 1.5 hrs of useful endurance and I'll factor in the slight weight change from fuel burn. Time and altitude will be recorded manually every 500' while my pilot friend does the flying as accurately as possible.
I've never seen any hard data on best glide speed, glide ratio, sink rate, etc... only "glides like a brick," "install lexan floor panels so you can see your engine out landing spot," etc. It's true that with the prop in, it does not glide well. With the prop out, it's quite respectable, being an aerobatic prop that goes to quite a high pitch. The manuals are not great having been produced so long ago. This will also produce a number for best range speed, speed for best endurance, and min sink speed (in case you have an engine failure over a decent spot and simply want to stay aloft for longer for troubleshooting and don't have to "get" somewhere.
Is there anything else y'all have been wondering but never tested?
