[aeroexperiments]

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[aeroexperiments]

Control and navigation in the white room
Part 2-- aerodynamics

1) Flex-wing hang gliders are vastly more stable with the bar pulled in. Pulling the bar well in and shifting one's weight a few inches toward one side will tend to put the glider in a stable turn in that direction, even if the glider was initially turning in an unknown direction. This is not at all true when the glider is configured for min-sink speed, i.e. near trim. In this case shifting a few inches to one side will likely lead to a very steep spiral in that direction.

2) Part of the reason for all this is that when the glider has a low angle-of-attack, i.e. a high sink rate with respect to the airmass, then it must constantly roll toward the inside of the turn just to hold the bank angle constant. The glider's natural aerodynamic roll damping tends to resist this, which tends to make the bank angle decrease, so that the glider requires some low-siding to hold it in the turn. This is a very intuitive situation. The opposite is true when the flight path is rapidly climbing with respect to the airmass, ie. under powered flight with a trike or power harness. In a steeply climbing turn, the aircraft must constantly roll toward the outside of the turn just to hold the bank angle constant. Now the aircraft's natural aerodynamic roll damping tends to make the bank angle increase. In an unpowered turn at a high angle-of-attack (low sink rate with respect to the airmass) the aerodynamic damping in roll does tend to decrease the bank angle but much less so than when the sink rate is higher. Also, the lower the turn radius (i.e. the lower the airspeed), the more the faster-moving, outboard wingtip tends to experience more lift than the slower-moving inboard wingtip, which contributes to roll instability.

3) Regardless of the details, it is vastly easier to control an aircraft when it is in a flight mode that requires low-siding than in a flight mode that requires high-siding, especially if the starting bank attitude is unknown! So if control and navigation fail while attempting controlled straight-line flight, and the G-load and airspeed are rising and falling erratically, it may be possible to sort things out by entering a stable turn by shifting to one side with the bar well pulled in…

4) Your mileage in towering cu-nim may-- make that WILL-- vary.

[SkyPilot]

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[Bobfly]

Instrument flying a weight shift glider in the white room does not sound like a pleasant pastime.

[Paul H]

There have been pilots who said that they could fly safely in white out conditions in the clouds using just a compass on their control bar, but that's hardly likely seeing as how that doesn't work in an airplane that is a lot more stable than a hang glider.

[ChattaroyMan]

I've flown in clouds quite a bit - in a Quicksilver MX. I wouldn't do it in anything else. Eipper's Quicksilver design has/had a lot of dihedral in the main wing making it very roll stable. To make turns in a Quick required constant roll control input. Once you brought the stick (or your weight in a weight shift design) back to center you were flying straight. I never got vertigo either - even spending upwards of 10 minutes in clouds. Most of the time I also keyed off of where the Sun was at - lightness/darkness in the cloud. This worked well coupled with such a roll stable aircraft. And, of course, all clouds I flew in were well away from hillsides. However, the longer I was in the white room the more I pondered this Far Side cartoon....

[aeroexperiments]

[noman3]

i have flown in the white room.When im in the white room i never pull in to much if at all.If you are pulled in,you could be doing wingovers and loops and not even know it.My 6030 gives me my direction and i always fly to the front of the cloud to ridge soar up the side of it.Never get into the white room when there are developing cu nims close by.I prefer the small cotton ball types,with no one around.

[knumbknuts]

[Bobfly]

Flight instrumentation for hang gliders is getting closer then you may think. These are for skiing but could be suited for flight with only minor changes.

http://www.zealoptics.com/transcend/

[johnpeace]

I've been lucky so far by using the following guidelines after inadvertently climbing into a cloud:

1. slow to trim or just a little bit faster...not too fast
2. return body position to center of the bar

That should have you flying in a more or less straight line

3. don't make any roll inputs

That should allow you to hold the heading you're on

A compass or GPS can help you to make tiny little heading changes to fly a straight line...but it's really difficult to keep it any more than +/- 15 degrees in either direction

4. wait until you pop out the side

It's a scary feeling and not fun at all. Even more so if there were other gliders in the thermal with you or there's a mountain back there somewhere.

I've flown with pilots who were very nonchalant about it and would even launch into a cloud bank, certain that they'd pop out the other side of the relatively thin clouds within seconds of launch.

Not for me, thanks.

I think the biggest mistake you can make after whiting out is trying to dive out of the clouds. At high speeds, the gilder is so much more sensitive to roll and pitch inputs that it's going to be virtually impossible to fly a straight line. Any little turn is going to increase the wing loading and contribute to your own spatial disorientation, causing you to make it worse with further, incorrect control inputs.

I just read a report of a pilot who tried that method and broke the glider, coming down under his reserve. Lucky for him the lift wasn't stronger or he'd have gone UP under his reserve, dragging the broken glider behind him!

[Derakon]

It sounds like one of the tricky problems of flying blind is not knowing your current roll angle. Are there no instruments that provide an artificial horizon? At the very least a bubble level would tell you if you're level or rolled to one side or the other, right?

[miguel]

I used the same method as JohnPeace. The cloud I was in, had mild turbulence in it. Whenever a wing got bumped up making a turn, I would turn in the opposite direction for the same amount of time. I popped out of the cloud over Highway 1 at Big Sur permanently cured of flying in clouds.

[johnpeace]

It's an extremely easy thing to avoid.

So easy, in fact, that it's a timewaster to imagine all of the techniques, gear and instrumentation one might use to make sure they can do it successfully if it's ever required.

Just stay out of the clouds, there...problem solved!

[zippidy]

[johnpeace]

[NMERider]

So far no one has mentioned: FAR Part 103.23 Flight visibility and cloud clearance requirements. Myself and many others have been reamed for posting videos of cloud flying which we all promptly removed and/or edited.

A bubble level is as useless as a plumb bob in a white out.

A GPS breadcrumb track can save you if you are inadvertently whited out so completely that the sun and Earth are no longer differentiated from the rest of the sky. Just make small corrections and keep an eye on the little icon. Bear in mind that the path of the icon can be delayed so stay on top of it.

if the GPS fails or malfunctions a cheap ball compass for $1 from Walmart can also save your skin. Just keep an eye on the ball inside the compass. If the ball starts to turn left then you need to chase it until it stops turning left. Simple as that. Stay ahead of it and you can avoid going into a spiral dive. AKA: Death Spiral.

I do not endorse cloud flying. Please follow the FARs! In certain conditions I have had clouds form underneath me faster than I could dive below the forming layer. If I was unable to remain a legal distance above the clouds and/or had to get down, then through the clouds I must go. It happens.

Be prepared and above all don't panic.

[zippidy]

[feathered1]

[Bobfly]

Feathered1 speaks with great wisdom.