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Flying wing gliding in high winds

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Flying wing gliding in high winds

Old 09-02-2012, 06:10 PM
  #1  
PDN777
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Default Flying wing gliding in high winds

Hi Guys (and gals),

I'm planning to drop a flying wing from a weather balloon,
at 35,000 feet or higher...

Winds up to 50 mph up there.

Flying wing makers can't really give me flight characteristics
in such winds.

For stability, and to minimize horizontal distance covered,
do you think it would be preferable to point the plane
directly into the wind (so it would be pushed backward, because
it's forward velocity would not be enough to overcome the wind),
or to fly spirals as it descends (in this case, it would also be pushed
in the direction of the wind because the upwind leg of the spiral
would not be strong enough to overcome the wind)?

Or perhaps would it be best to have it fly with the wind (is this
the most stable orientation in a high wind?) and have it be
in a dive to get it thru the high winds as fast as possible...

Other ideas for a stable return home, preferably minimizing
horizontal distance covered?

And please share any direct personal experience with flying
a flying wing as a glider in high winds.

Thanks!

Prahas
Old 09-02-2012, 06:44 PM
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tschuy
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Default RE: Flying wing gliding in high winds

Does it matter? The wing will be at a zero speed as it will be traveling the same speed as the weather ballon. However it will gain speed quicker from the launch if it is pointing into the wind.

My assumption is that you'll have the proper approvals and wavers from the FAA...
Old 09-02-2012, 07:35 PM
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huck1199
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Default RE: Flying wing gliding in high winds

What for???
Old 09-02-2012, 08:02 PM
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speedracerntrixie
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Default RE: Flying wing gliding in high winds

The airplane has no idea that there is that much wind. All it see's is airspeed. I'm quite sure that the terminal velocity would be greater then 50 MPH so keeping it into the wind will still give forward motion. No matter which way it's going, it will have the same airspeed.
Old 09-02-2012, 08:39 PM
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Default RE: Flying wing gliding in high winds

The balloon and glider are both travelling with the wind, the glider will simply orbit the balloon if it is trimmed to fly in a circle. Neither have any idea that the wind is moving them over the earth. You, on the ground, will see them both moving away downwind. If you don't want to chase the glider too far, then you will have to trim it to fly dead straight, and release it straight into the wind. The glider will always fly at trimmed speed, its speed over the ground will be the vector sum of the wind and glider speeds.
Evan, WB #12.
Old 09-03-2012, 05:43 AM
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PDN777
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Default RE: Flying wing gliding in high winds

Hello Folks,

Thanks for all the replies.

There are several issues here.

@tschuy the wing certainly will have ground speed at the time of release:
the same ground speed as the balloon, created by the wind. When you
say, "it will gain speed quicker from the launch if it is pointing into the
wind," do you mean air speed or ground speed? I would think in
both cases it would speed up faster if it pointed down and away
from the wind... And yes, I am working with the FAA to get clearance.

@huck1199 why climb a mountain? Because it is there! ;-)

@speedracerntrixie: I think the plane does feel the wind. See:

http://www.youtube.com/watch?v=-m4nnZgnVBw

http://www.youtube.com/watch?v=4LkZW-9rbvI

The first video demonstrates what happens when the headwind
is stronger than the max forward velocity of the plane.

The second demonstrates the effect that gusty, high winds
have on a wing.

I should have said gusty high winds, because often,
at 35,000 feet, there are many gusts.

Thus I am concerned about stability.

Yes the airspeed remains the same. But the ground speed changes.
Assuming you are correct, and the max velocity is higher than
50 mph (for now, let's say 70 mph in calm wind), if we point into the wind,
ground speed becomes 20 mph, and if we point away from the wind,
ground speed becomes 120 mph. 120 mph covers too much ground
we'll have to drive 3 hours upwind to launch the balloon, which means
leaving at 3 am!!!

So can I point into the wind, and fly backwards at 20 mph for a
long distance (under autopilot). This doesn't feel very stable to me...

I'm leaning towards a spiral approach as I write...

@pimmnz the first part of your answer is a good description
of what happens on the way up. The second part contradicts my last
paragraph. You seem to think trimming it dead straight into the wind
will result in a stable flight...When I look at video #1 above I'm not
so sure... Video #2 also gives me pause...

Anyway, any more thoughts on the matter would be much
appreciated. In particular, what are your thoughts about programming
a spiral flight pattern, so it circles down, blown by the wind as it
goes...

Thanks again!!!
Old 09-03-2012, 08:30 AM
  #7  
speedracerntrixie
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Default RE: Flying wing gliding in high winds

I think you are still off base. In both cases you posted light airplanes flying in strong slope lift. The " Wind " is being directed upward by the slope and thus providing lift. In the first video the combination of lift and wind speed exceeded the gliders terminal speed because the wing loading was too light. Increasing the airplanes wing loading would yeald a higher mass. Mass= potential energy, pointing the nose down would convert potential energy into kinetic energy which means speed. If you went further with your serches you would find an R/C glider doing well over 400 mph ground speed on a slope site that has winds blowing 60 mph.
Old 09-03-2012, 08:45 AM
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RCPAUL
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Default RE: Flying wing gliding in high winds

If this is a model, you are above the 400 ft. ceiling that is allowed by the FAA. If this is a research project I assume you have the proper clearances?
Old 09-03-2012, 09:29 AM
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speedracerntrixie
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Default RE: Flying wing gliding in high winds


ORIGINAL: RCPAUL

If this is a model, you are above the 400 ft. ceiling that is allowed by the FAA. If this is a research project I assume you have the proper clearances?

The 400 FT ceiling is only law if you are 3 miles or less from an active airport. The AMA sanctions Pattern, IMAC and soaring events that are impossible if one is limited to 400 ft.

Old 09-03-2012, 10:26 AM
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PDN777
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Default RE: Flying wing gliding in high winds

@speedracerntrixie writes:

"In both cases you posted light airplanes flying in strong slope lift. The " Wind " is being directed upward by the slope and thus providing lift. In the first video the combination of lift and wind speed exceeded the gliders terminal speed because the wing loading was too light. Increasing the airplanes wing loading would yeald a higher mass. Mass= potential energy, pointing the nose down would convert potential energy into kinetic energy which means speed. If you went further with your serches you would find an R/C glider doing well over 400 mph ground speed on a slope site that has winds blowing 60 mph. "

Yes yes yes!!! As I've looked more, I've found that adding weight raises term. speed. So I'm gonna fly a heavy wing!

And yes, I've seen the 468 mph dynamic soaring video. Fabulous! Alas, the glider is too pricy for our budget...
But it gives me hope that we can find a plane which can withstand 60-70 mph no problem.

Another pilot mentioned to me that even if the head wind exceeds the plane's term. speed,
so it has a negative ground speed (ie, flying backwards), from the plane's point of view,
it still has airspeed and air flow over the wings. So it should be able to fly backwards,
reasonably stable, for a long period. Does this sound right to you folks?

@RCPaul, as I mentioned above, I am working with the FAA to obtain clearance. As it is a combo
weather balloon / RC project (two different sets of regs), we may need a waiver. But my
contact at the Center nearby says we may be able to get it. And we can plan launch and
landing sites far from airports.

Any other observations more than welcome!

Prahas
Old 09-03-2012, 10:45 AM
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hattend
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Default RE: Flying wing gliding in high winds

My first concern would be having a radio with the range to control the plane (or did you say you have on board autopilot?)

When Maynard Hill was setting altitude records in the 70s, he used a directional antenna on ham freqs (I believe)

If you pick your weather days carefully, you can have a flight to 35K with little to no wind drift. With a high pressure ridge practically over your head, you could get to 100K with as little at 4 miles of drift. I launch weather balloons for a living (NWS) and I have had many flights where the winds reverse above the tropopause (about 40K) and the balloon drifts back over the station. I once tracked a balloon to landing less than 4 miles away with a flight to 102K.

Good luck!
Don
Old 09-03-2012, 12:44 PM
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JohnBuckner
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Default RE: Flying wing gliding in high winds

Launching from a balloon the relative wind (relative to the balloon and the glider) will be zero.

At 35 thousand you will certainly be well in to positive controlled airspace will you be operating with an air traffic control clearance or window?

John
Old 09-03-2012, 01:13 PM
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Default RE: Flying wing gliding in high winds

I realy really really wish some of you would sit down and learn the difference between the AMA safety code (NOT A LAW) and 14 CFR Part 91 (A LAW) and any associated Adivisory Circulars that tell you how to safely comply with that law.

With respect to the OP
§ 101.37 Notice requirements.
(a) Prelaunch notice: Except as provided in paragraph (b) of this section, no person may operate an unmanned free balloon unless, within 6 to 24 hours before beginning the operation, he gives the following information to the FAA ATC facility that is nearest to the place of intended operation:
(1) The balloon identification.
(2) The estimated date and time of launching, amended as necessary to remain within plus or minus 30 minutes.
(3) The location of the launching site.
(4) The cruising altitude.
(5) The forecast trajectory and estimated time to cruising altitude or 60,000 feet standard pressure altitude, whichever is lower.
(6) The length and diameter of the balloon, length of the suspension device, weight of the payload, and length of the trailing antenna.
(7) The duration of flight.
(8) The forecast time and location of impact with the surface of the earth.
(b) For solar or cosmic disturbance investigations involving a critical time element, the information in paragraph (a) of this section shall be given within 30 minutes to 24 hours before beginning the operation.
(c) Cancellation notice: If the operation is canceled, the person who intended to conduct the operation shall immediately notify the nearest FAA ATC facility.
(d) Launch notice: Each person operating an unmanned free balloon shall notify the nearest FAA or military ATC facility of the launch time immediately after the balloon is launched.

§ 101.39 Balloon position reports.
(a) Each person operating an unmanned free balloon shall:
(1) Unless ATC requires otherwise, monitor the course of the balloon and record its position at least every two hours; and
(2) Forward any balloon position reports requested by ATC.
(b) One hour before beginning descent, each person operating an unmanned free balloon shall forward to the nearest FAA ATC facility the following information regarding the balloon:
(1) The current geographical position.
(2) The altitude.
(3) The forecast time of penetration of 60,000 feet standard pressure altitude (if applicable).
(4) The forecast trajectory for the balance of the flight.
(5) The forecast time and location of impact with the surface of the earth.
(c) If a balloon position report is not recorded for any two-hour period of flight, the person operating an unmanned free balloon shall immediately notify the nearest FAA ATC facility. The notice shall include the last recorded position and any revision of the forecast trajectory. The nearest FAA ATC facility shall be notified immediately when tracking of the balloon is re-established.
(d) Each person operating an unmanned free balloon shall notify the nearest FAA ATC facility when the operation is ended.


The above free baloon requirements are LAW
Old 09-03-2012, 01:16 PM
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Default RE: Flying wing gliding in high winds

PDN, your question did not state that the glider was controlled, and a 35,000 ft there is no slope lift...nevertheless, the statements I made are true. With reference to your question whether the the glider will 'fly backwards in a stable manner for some time' you should realise, by now, that the thing is never, at any pont, flying backwards. It is always flying at the trimmed speed as determined by its weight, elevator trim position and wing Cl. If gust stability is going to be a problem, then adding a little 'self righting' ability will take care of that. Perhaps the easist way to do what you are proposing is to simply launch a F/F, circle trimmed glider from the balloon and allow yourself and the balloon to descend at the same rate as the glider, though what you will do if the glider catches some thermal lift....
Evan, WB #12.
Old 09-03-2012, 02:00 PM
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DGrant
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Default RE: Flying wing gliding in high winds


ORIGINAL: RCPAUL

If this is a model, you are above the 400 ft. ceiling that is allowed by the FAA. If this is a research project I assume you have the proper clearances?
HAHAHAHAHAHAHAHHAHAHAHAHAHAHAH>>>HAHAHAHAHAHAHAHAHAHAHAHAHA..... HAHAAHahahhahahahhaHAHAAhahahah... thanks for the laugh. HAHAHAhahahaha....

People are so amazing.. proper clearances... haha.. give me a break.. .. I needed a good laugh..
Old 09-03-2012, 04:45 PM
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PDN777
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Default RE: Flying wing gliding in high winds

This is fun!

@hattend: yes, we have autopilot on board. WRT balloon drift: I've run dozens of balloon trajectory models in my area (N. AZ), and once or twice, when going high, we've drifted back towards the launch. But 98% of the time it is a west to east flight. Even on calm, early mornings, as you go up, winds get heavy most days.

@MajorT: I'm very familiar with 14 CFR Part 91. The first launch we did adhered to this laws, and this launch will too. My contact at the FAA says they are looking at new regs for unmanned flight, drones, etc, because of all the new tech, and law enforcement's desire to use unmanned drones for local surveillance. At any rate, working with the FAA and my other contacts, one way or another, I'll get a legit clearance before launch.

@pimm: you write, "launch a F/F, circle trimmed glider from the balloon and allow yourself and the balloon to descend at the same rate as the glider, though what you will do if the glider catches some thermal lift...." What's an F/F? And what do you mean by allowing myself to descend? It's a weather balloon, not a manned hot air balloon. ;-) The other things you say make sense to me. And thermal lift is another problem which I haven't looked at yet...

@Dgrant: my heart laughs with you... oh, to be free the way the Wright Brothers were free... alas, the skies are simply too crowded to ignore the regs (at least, that's how I look at it).
Old 09-03-2012, 06:43 PM
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Default RE: Flying wing gliding in high winds

Assuming you are talking of a flying wing like a Zagi. I have flown the snot out of these for years in full contact combat and dynamic soaring as well as everyday soaring. It will not matter HOW you drop it, just start with the controls at neutral eg normal flight and it will sort itself out in less than a 100 feet.

Speed? a lightweight Zagi can manage 50mph in a shallow dive. See [link=http://www.youtube.com/watch?v=iCYBU7-Bszw]CLICKY[/link]

A ballasted Zagi can exceed a 100mph although if DSing one they come apart at around that speed. Ask me how I know this. This is not mine but a similar sort of thing See [link=http://www.youtube.com/watch?v=o7-iZf44pC0]CLICKY[/link]

I am assuming you intend to drop it and then fly it back to the launch point. If the balloon climbs faster than the L/D of the glider then that should not be a problem. Program the AP to fly directly towards the launch point then circle around the launch when it gets there. Assuming your AP has a 3D GPS input then programming it to attain the best flying speed to make best use of the height avaialble is a trivial ex. Allowing for a descent into lower wind speeds not quite so trivial but if you start with a relatively fast flying wing it will not be an issue. It will get back to you.
Old 09-03-2012, 06:59 PM
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Default RE: Flying wing gliding in high winds

As already stated, the aircraft can fly backwards if the speed of the air is greater than the glider's airspeed. If the air is moving at 100 (knots, mph, whatev), and the glider is moving against it at 50, the glider will be going backward geographically. 

First-time poster, not the best areas to be asking about IMO. Questions seem elementary, could be answered with a simple search. 
Old 09-04-2012, 12:06 AM
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Default RE: Flying wing gliding in high winds

F/F = Free Flight. ie, uncontrolled. I begin to see that you want to release an R/C wing from 35,000 ft and fly it down to the ground. Unless it is autonomous, it's gunna be a difficult to see, yes? It would need a degree of self stability, which your average 'Zagi' type does not have, and a programmed heading to seek. I forsee a degree of difficulty, it's really cold at 35,000, and there is not a lot of air to be had, most of it is underneath you that far up, so although IAS will be the same as sea level TAS (and therefore speed over the ground) will be considerably higher. These questions you have could be answered with a search of the usual aerodynamics data bases, NASA etc. This is likely not the forum for thse questions, someone will have done this before, and most of the UAV's already operate in this area, so the answers should be 'out there'.
Evan, WB #12.
Old 09-04-2012, 08:02 AM
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Default RE: Flying wing gliding in high winds

You need more than a waiver to fly above FL180. You need a transponder.

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