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Old Sep 17, 2004, 06:34 PM
Space Glider Project
Tristar500's Avatar
Greensboro, NC
Joined Feb 2004
186 Posts
seeking large field for High altitude launch in VA, or WV

Hello all,

My name is Lawrence Feir, I'm leading a small team of 5 guys who are looking at putting a small unmanned aircraft in near space later this year. The aircraft is guided by a GPS and has an onboard computer. It gets to its target altitude of 100,000 feet via a helium weather balloon. One it cuts itself free the unpowered glider makes its way back to the launch site and a couple of hours later if all goes well it lands at our feet.

We are looking for a large field located in north central Virginia or West Virginia to conduct a few low altitude tests. First flight will be to 5,000 feet and if all goes well we’ll fly a few more times and go higher each time.

If any of you live in this area and would like to get involved in the project Please let me know. We’d like to do this sometime in the first week or so of October of this year (2004) and Yes! there is a camera onboard!
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Old Sep 17, 2004, 06:40 PM
De-Brushed user
Midland, Tx / W. Lafayette, Ind.
Joined Dec 2002
2,949 Posts
If you want to move out here to west Texas, i know plenty of large areas you can fly from

LOL, low altitude test, 5000 feet! This looks to be a very cool project, good luck and keep us posted.
Jonathan
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Old Sep 17, 2004, 08:25 PM
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Somerset, Pennsylvania, United States
Joined Jun 2004
545 Posts
I dont know of a field but I am in southwestern pa and would love to come and see this sounds awesome! at the very least I hope you post results/updates here!
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Old Sep 17, 2004, 11:02 PM
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MGBGTRacer's Avatar
USA, VT, Springfield
Joined Jan 2004
3,858 Posts
There are some country airports around that can probably accomodate you- I assume you coordinate it all through FAA etc, right? Did you have a more specific area than just VA or WV? I can approach the airport manager at a rather remote country airport out in the sticks of Northern VA.
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Old Sep 18, 2004, 07:04 AM
Space Glider Project
Tristar500's Avatar
Greensboro, NC
Joined Feb 2004
186 Posts
Country airport will work fine. Reason for the location to be in VA or WV is that it is the half way point between myself and one of my teammates. (He's in Philadelphia)

We are working with the FAA. Note, Although I am an AMA member, AMA rules forbid autonomous flight. We do not consider this an radio controlled airplane but rather a UAV. Such that we would be breaking AMA rules if we were to fly at a AMA sanctioned field.

I had thought of the small airport idea before. Almost seems like the airport guys would prefer you to lauch right there so they would now what we're doing reather then the reqired telephone call to the local ATC.

Cheers, Lawrence
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Old Sep 18, 2004, 11:23 AM
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thermite's Avatar
London, England
Joined May 2003
1,598 Posts
Sounds great Lawrence. I've read of this very same thing being done before. What type of model are you using and what will all the equipment consist of?
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Old Sep 18, 2004, 12:05 PM
Space Glider Project
Tristar500's Avatar
Greensboro, NC
Joined Feb 2004
186 Posts
We will be carrying several cameras. The aircraft is also carrying a radio modem that beams down it's GPS data as well as video and photos. Microcomputer autopilot of our own design guides the airplane throughout the mission.

Here's a photo of our all carbon fiber test aircraft. We've been flying it with a pusher brushless setup for testing. final config is a pure glider.
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Old Sep 18, 2004, 01:55 PM
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thermite's Avatar
London, England
Joined May 2003
1,598 Posts
Very nice! Could you explain the x-wing type tailplane?
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Old Sep 18, 2004, 06:35 PM
Space Glider Project
Tristar500's Avatar
Greensboro, NC
Joined Feb 2004
186 Posts
Sorry so long here but here is an excerpt from a previous press release. It's got more info in it than I could possible jot down in a few lines.

Why the Funny Tail Surfaces?
A conventional airplane normally has a horizontal tail for pitch control and longitudinal stability, and a vertical tail for steering and directional stability. Airplanes also normally have ailerons on the wings for roll control. All of these control surfaces could keep an autopilot very busy. Besides keeping an eye on which direction is home, the autopilot would need to keep the nose from getting too high or too low (which would cause the glider to go too fast or too slow), and it would also need to keep the wings level when flying straight and bank the wings when making turns. If the autopilot messed up on any one of these tasks we would lose the airplane.

To keep the number of possible failure modes as small as possible, and also to keep to a minimum budget, our hope is to fly with a very basic autopilot that has to do only one thing: point towards home using the on-board GPS that knows where it is at any moment and which direction is home. All of the other functions (nose up, nose down, speed up, slow down, wings level, banking for turns) will be automatically taken care of if we design the aircraft with just the right amount of natural stability in all three axes (pitch, roll and yaw).

Pitch stability will be provided by the two horizontal tails. Because of their size and the angle at which they are mounted, if a gust of wind should cause the glider’s nose to drop, the speed will begin to increase. This will put greater downward airloads on these tails, tending to bring the nose back up. Likewise, if the nose gets a bit too high and speed decreases, these loads will change and cause the nose to move back down. Done right, the glider will always want to get back to its steady glide angle all by itself.

The small vertical tail that points downward (called a ventral tail), is there to provide directional stability. Like the fin on a weather vane or the feathers on an arrow, the purpose of the ventral tail is to help keep the airplane pointing into the wind and flying straight. Like the horizontal tails, if the ventral tail is the right size and mounted at the right angle, it will do its job all by itself with no need for any moving parts.

The two V-tails (or butterfly tails) are the steering surfaces. These are the only surfaces the autopilot will have to control in order to bring the airplane home. If the autopilot sees that it needs to turn to the right, it will deflect the control surface on one of the V-tails upward and the other just slightly downward. To turn in the opposite direction, it will deflect opposite surface up and the other slightly downward. What follows is both complicated and amazingly simple.

With one of the V-tail control surfaces deflected up and the other down, part of the resulting forces will push the glider’s tail towards one side. This will cause the nose to turn in the desired direction, and the glider will seem to slide slightly sideways (what pilots call a “sideslip”). This will cause one wing to generate slightly more lift than the other, so the entire glider will begin to bank and a smooth turn will begin. Unfortunately, the nose will tend to drop towards the low side, and if this continued unchecked the aircraft would soon be in a rapidly tightening “death spiral.” However, because of the angle at which they are mounted and the way they are operated by the autopilot, regardless of which way the autopilot wants to turn, it deflects one surface up more than it deflects the other one down, so the net effect is that besides the desired turning effect, every turning command is accompanied by a nose-up pitch effect that keeps the nose from dropping and starting the death spiral. The trick is to get the angles and surface areas just right so that the aircraft will make smooth gliding turns in whatever direction the autopilot calls for, without gaining speed, losing speed or running away in a spiral dive.

On paper these flight dynamics can only be estimated roughly, so one of the early objectives of the radio-controlled flight tests with a motor on the prototype glider will be to get the angles and areas right and harmonize the up and down motions of the control surfaces on the V-tails to get the desired smooth turns. For these tests we will have control surfaces on the horizontal tails and flaperons (combination flap/ailerons) on the wings, so that we can control the bank and pitch as needed as well as slow down the aircraft for landing. The aim will be to fine-tune the control surfaces on the V-tails until the aircraft can be flown with the V-tails alone and the other surfaces locked in place. Then for the actual high-altitude gliding flights, the autopilot will only have to tend to the V-tails to get home while gravity and aerodynamics take care of the speed and altitude.

Lawrence
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Old Sep 18, 2004, 07:28 PM
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Sparky Paul's Avatar
Palmdale, CA
Joined Oct 2000
13,465 Posts
It is overly complicated.
A simple vee-tail with the autopilot commands mixed with the radio commands will work in a less parts intensive and failure prone manner.
The fewer parts the lower the chance of failiure.
Longitudinal stability, apparently your main concern, is a product of the areas of the wing and tail, and the center of gravity. It can be built in to such an extent the autopilot's task is reduced to an attitude hold condition. The airplane will do the work.
Adjusting the servos for the tails to provide the differential can be done with the control system geometry in the plane, or at the transmitter.
In addition, combining the extraneous surfaces into two will reduce the induced and parasitic drag of the multiple surfaces you have.. two fewer tips, and a much reduced interference at the fuselage junction.
And, white on top at least, for composite construction.. Black is a heat sucker, and can create bulges and delaminations in the layup.
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Old Sep 19, 2004, 12:28 AM
Registered User
Carson City, Nevada, United States
Joined Aug 2002
172 Posts
At 100,000 feet the temperature is something like minus 50 celsius. One of the biggest hurdles will be keeping the battery from freezing. Heat sucking black might be a good thing....
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Old Sep 19, 2004, 02:12 AM
Space Glider Project
Tristar500's Avatar
Greensboro, NC
Joined Feb 2004
186 Posts
Quote:
Originally Posted by Sparky Paul
It is overly complicated.
A simple vee-tail with the autopilot commands mixed with the radio commands will work in a less parts intensive and failure prone manner.
The fewer parts the lower the chance of failiure.
Longitudinal stability, apparently your main concern, is a product of the areas of the wing and tail, and the center of gravity. It can be built in to such an extent the autopilot's task is reduced to an attitude hold condition. The airplane will do the work.
Adjusting the servos for the tails to provide the differential can be done with the control system geometry in the plane, or at the transmitter.
In addition, combining the extraneous surfaces into two will reduce the induced and parasitic drag of the multiple surfaces you have.. two fewer tips, and a much reduced interference at the fuselage junction.
And, white on top at least, for composite construction.. Black is a heat sucker, and can create bulges and delaminations in the layup.
Hi Paul, Please understand that the prototype aircraft you are looking at is just one our testbed aircraft. In fact no two prototypes have been the same as we derive information and knowledge from each version and make changes and improvements in each succeeding design.

While a simple V tail may work, our present design offers many advantages. We’ve been experimenting for nearly a year so I couldn’t begin to list all the experiments and results we have had in this time. What I can tell you about the design is that it has been optimized for controlled flight in the near vacuum (1% atmosphere) at near supersonic speeds. Our aeronautical engineer has calculated a maximum speed of .7 mach shortly after the release. The aircraft will loose nearly a mile of altitude before pulling out of the dive.

As the Space Plane is a glider there is no reasonable way an altitude hold function would work and as the aircraft is completely autonomous there is no transmitter. We can communicate with the aircraft via modem to program course changes etc and to download photo and video.

As far as the color of the aircraft. It will probably be white and fluorescent orange for maximum visibility. Temperatures at our target altitude are expected to reach –90 F so proper insulation is imperative.

Hope this answers some of your questions…

Lawrence
Team Leader/Space Glider Project
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Old Sep 19, 2004, 06:32 AM
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thermite's Avatar
London, England
Joined May 2003
1,598 Posts
Intersting stuff. I look forward to seeing more reports.
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Old Sep 19, 2004, 10:27 AM
SIU Aviation
Kyle G.'s Avatar
Wheeling, Illinois
Joined Dec 2003
5,240 Posts
yes, after reading through this I think this is going to be a very interesting experiment/test. can't wait for the results.
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Old Sep 19, 2004, 10:32 AM
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thermite's Avatar
London, England
Joined May 2003
1,598 Posts
I have seen this done before somwhere from a link on this forum but I don't think they got that altitude, you could definitely see the curvature of the Earth and a little darkness above.
Lawrence, how far (depending on winds obviously) have you anticipated the drift on the ascent?
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