Ep 4 - Longitudinal (Pitch) Stability - Task-Based Flight Test Series

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Getting your experimental aircraft to feel like a normal aircraft in the pitch axis. Not having designed this aircraft, I was left with four variables to improve some objectionable pitch stability characteristics.
0:00 Intro
2:10 Airborne Flight Test
2:43 Backcountry Bogey Update
4:19 Longitudinal Control Test Card 5
5:36 Static Longitudinal Stability Test Card 14 (Stable Slope)
10:32 Pull Test
13:25 Push Test
15:37 Dynamic Longitudinal Stability Test Card 17
20:45 Thrust Disturbance Longitudinal Reaction Test
23:30 Flow
24:42 Oshkosh
25:29 Ep 3 Pinned Comment
26:59 Longitudinal Stability Primer
31:48 RANS' Randy Schlitter's input
33:50 Federal Aviation Regulations on aircraft stability
38:06 My Fix

[@ibgarrett]

I was looking for an update here just last night! :) I'm flying now and starting to jam through the tasks... working out the squawks... I'll watch this video here this evening. :D But I got to get through the testing to fly it to Oshkosh. :D

[@craigsanders6925]

Love the testing updates, someday I'll build and this give me more insight on the process after completion.

[@HollywoodRebel]

I really enjoy these videos. I nerd out about all this because I find it very fascinating how these things can fly.

[@Joe_Not_A_Fed]

125kts. Noice. In a not at all bad way, every flight should be looked at as a test flight...which I am willing to bet, is SOP in the Steve brain. I can't tell you how much I am enjoying these detailed breakdowns and debriefs. I assume the flight testing you did in this vid, was post horizontal stab incidence increase. From where I am sitting, it seems you have (for lack of better words) a soft recovering aircraft from longitudinal deviations. It definitely wants to go up when you dive and go down when you climb in the testing, but it's not abrupt or twitchy about it. I look at neutral stability like trying to balance on a ball. When every direction is on the table...you have to wait until something happens, to know which way to push, pull or kick. It's kind of like no wind or a little crosswind on final. With no wind, you have to control in both directions. With a bit of crosswind (or a lot) your inputs will always be in one direction...just to a greater or lesser degree. I dunno. Maybe that's just me. It makes sense to me, that the lack of return to the starting speed is likely due to the fixed pitch prop. Good catch, that. Something like that, which seems like it could be a potentially serious anomaly, could really vex a person. Engines can be notoriously slow to gain back, or lose, that last bit of set engine speed without a bit of help. Speaking of...I can't help but think that eventually...you're going to start thinking that the last piece of the 'perfect Bogey' puzzle...is a constant speed prop. I would like to take credit if (when) it happens...but I suspect that nugget has already been planted. Thanks for sharing, Steve.

[@s-21project92]

Good stuff, Steve! Thanks for documenting and sharing your observations and thoughts. Very helpful to those of us that will be going through pahse-1.

[@CLEAREDDIRECT]

You're welcome, Tony! You've been a big help to me. Now git 'er flyin!

[@brianberezowski5352]

Cool video Thank you for sharing all that information. Any info that makes us better / safer pilots is GOOD info. Looking forward to your next video whether it be back country flying or more test flights. Two thumbs up from CYQT. 👍🇨🇦👍

[@gregmanzie6109]

G’day Steve Hopefully you are enjoying Oshkosh 2024. I have previously discussed with you that my elevator horn is also sticking up in cruise flight. I am planning to raise my horiz stab as you did. You have mentioned your overall adjustment was raising the leading edge 15mm. Are you still happy with the result? If you were doing it again would you go to the full 15mm adjustment? Thanks Greg