Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by DaveD, Oct 21, 2017.
Topic for today is controls...
I was thinking ...... does the tapered wing twist at high AOA and is it in favorable direction for the stall?
This is a really great series, fun to read and very engaging, thanks for sharing.
Lowering the flap lowers the stall angle of attack (if you don't use sluts or LE flaps). That gives "natural" protection against tip stall.
That almost got me once, doing a high-speed pass and aggressively pulling up I had a really aggressive wing-drop during an accelerated stall with full negative flaps (-7 degrees, which puts the ailerons at about -4 degrees). If you simply always pull a modest bit of flaps below 100 kts, otherwise "flapped tip stall protection" should be fine.
Burning the midnight oil tonight!
Trim Tabs are today's topic.
Cockpit design is tonight's subject:
Propeller theory for beginners! Trying to put prop design in simple terms is a bit like trying to put nuclear physics in simple terms... in other words, quite a challenge. But I do like a challenge.
A couple of articles on Spinning and Design for Spin Prevention are now posted
Loading and V-n diagrams will be up in a couple of hours.
Many thanks for your efforts. That's a lot of writing.
I had a couple of days off, but limit loads and forces in general is now up:
For those needing structure I'll try and introduce some! I've added an index to the blog:
And for the rest of you, here's where I'm up to (Gust Loading has just been posted):
Introduction - In The Beginning
Designing My Own - Design Notes
Configuration & Layout - Configuration & Layout
Wing Shape - Wing Shape
Aerofoil Selection - Aerofoil Selection
Drag - Such a Drag
Materials - Material World
Flaps - All in a Flap
Landing Gear - Happy Landings
Stability - Introduction - Are You Unstable?
Stability - Longitudinal - Perfect Pitch?
Stability - Weight & Balance - A Weighty Issue
Stability - Lateral & Directional - Thinking Laterally
Fuel Systems - More Fuel You?
Cooling - Keepin’ Cool
Controls - Control Freak
Trim Systems - Just a Trim
Cockpit Design - The Workshop?
Propellers - Prop Me Up
Spins - All in a Spin
Design for Spin Safety - The Spin Doctor
Aircraft Loads - Shouldering the Load
Limit Loads for Design - Feel The Force
Gust Loading - Gone With The Wind
In response to some feedback I've gone back through my earlier posts and linked the images to the original "supersized" versions. So if you were having trouble with the diagrams being too small to read easily, you can now click them for a big version:
Secondly I've posted a couple more:
Biscuits-Jelly-Nylon-Steel - This is a discussion about the four pillars of engineering: Stress, Strain, Strength and Stiffness (the four 'S's). This is a personal bugbear of mine, everyone who ever thought about designing anything (even "eyeball" engineering) should have a grasp of these concepts! You don't need to be a professional engineer to realise this stuff is fundamental (Oh and for those not of an English persuasion, "Biscuits" are cookies!)
The Path To Enlightenment - Load Paths, vitally important for any design and require an understanding of "Stress, Strain, Strength and Stiffness"...
A few more links for you:
For those who like a good STOL: Short & Sweet
A slightly more in-depth examination of prop effects: The 'P' Factor
And finally, Why do you get swept wings on subsonic planes? A Clean Sweep
The four automatic slats on the Helio operate independently (no interconnection mechanism), depending only on local angle of attack. (Flaps, aileron, yaw, etc.)
Good summary of the various and confusing "P effects".
Wow, that's interesting! I assume it must have enough aileron authority to counteract an asymmetric slat deployment even at low speed. The fact there are two separate slats on each wing probably helps.
I don't think there is any asymmetric lift to deal with. They automatically balance the lift. Need to ask a Helio pilot how they work. But as I recall they pop in and out no problem on the ball bearing rollers.
I have removed them for painting. But never flew in a Helio.
The Helio ailerons are wide chord but only about 4’ long because of the near full span flap. They have an effective spoiler (interceptor) behind the main spar to augment roll.
You're right, and my previous post was poorly worded! Slats mostly push up the stalling aoa rather than significanly increase lift at a fixed aoa. So the concern from an asymmetric deployment is presumably having one wing stall at a lower aoa than the other and causing an asymmetric stall (in all probability at low speed and close to the ground!!)
Trying to save a wing drop with aileron is a bad idea, but if the Helio has spoilers for augmenting roll (something else I didn't know!) then the spoilers may be able to counteract an asymmetric slat deployment even at stalling speeds.
I interviewed the Helio display pilot last summer at Oshkosh. He said it just doesn't stall! No wing drop. No spin.
Really, everything the NTSB wants to prevent LOC, the number one goal.
So I went straight to the NTSB booth and told them to check it out. They both had no clue what I was talking about.
No stall does not mean it can't sink at 1000ft a min. You still have to fly it.
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