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Flight Test Log 1

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Summary
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A series of subscale flight tests were done on a model of the Subvehicle
Carrier (SVC), which is intended to carry the Precision Air Deployment
vehicle (PAD). Testing, combined with modifications to the SVC airframe,
resulted in improvements in lateral control of the SVC/PAD compared to the
design submitted in the previous year's IARC competition (XE2/PAD).

Roll control in particular seems to be much improved. The XE2/PAD was very
difficult to turn, and had nonexistant aileron control, according to the
test pilot. A considerable amount of rudder deflection was required for
steering.

Poor climb rate was another problem with the previous design. Rate of climb
is sensitive to the drag coefficient CD, and the CD due to the PAD is probably
much smaller in the new design because of the different geometry, simpler
flow field, and substantially smaller wetted area. Although rate of climb was
not measured on the new design, qualitatively it seems more than adequate.

Regarding maneuverability -- one surprise was that the SVC can apparently
maintain a very high angle of attack (at least 30 deg) under certain
conditions. This behavior should be investigated further.

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| Picture, subvehicle carrier with PAD |

| Picture, subvehicle carrier with PAD |


| Picture, subvehicle with open hatch |

| Picture, subvehicle with open hatch |

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   Test ID:  1
      Date:  2004/09/28
      Time:  Afternoon
      Wind:  Calm
   Vehicle:  SVC, SVC/PAD
     Scale:  41 %

First flight. Unpowered glide, controls fixed, hand launch. Several flights
were done, with and without PAD attached.

I didn't see any obvious problems except for a slight yaw oscillation during
one flight. Possibly the vertical tail area needs to be increased to
compensate.

                             BATTERY

                       Supplier:  FireBird pack (modified)
                      Chemistry:  NiMH
                Number of cells:  7
                        Voltage:  8.4 V
                       Capacity:  300 mAh
                           Mass:  57 g

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On 2004/10/11, the vertical tails were enlarged slightly, and the boattail
was reshaped to decrease drag.

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   Test ID:  2
      Date:  2004/10/12
      Time:  --
      Wind:  Breezy
   Vehicle:  SVC, SVC/PAD
     Scale:  41 %

The SVC was flown with and without PAD installed. Although it was too windy,
given the very low wing loading of the airplane, I went ahead and tested
anyway.

Performance seemed OK with and without the PAD, but I had difficulties
controlling vehicle. It's not clear what caused the control problems -- wind,
design deficiencies or lack of piloting ability.

Several hard landings resulted in minor damage -- there were several dings in
the foam structure, plus two small foam pieces were broken from the nose. The
wing snag was true to its name -- a small twig was snagged during one landing.

The vehicle overturned during one landing with the PAD on top. There was no
apparent damage to the PAD.

On the last flight, the motor came off during flight and the propeller
torque twisted the electrical leads to the motor. Fortunately the motor
stayed attached to the airframe, hanging on by its leads, which prevented
the center of mass from moving too much. Also, the battery came partially
loose, and the R/C receiver was pulled out of its plastic sleeve. Damage
turned out to be minor.

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   Test ID:  3
      Date:  2004/10/23
      Time:  --
      Wind:  Calm
   Vehicle:  SVC
     Scale:  41 %

Tether was used, with and without a plastic pole. Pole was 3.1 m (10 ft) long.
Vehicle was controls-fixed, unpowered. Flew OK, stable in pitch.

Results suggest we should consider tethered tests in the future for PAD
separation tests, or for other testing at sites where there isn't enough
room for free flights.

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   Test ID:  4
      Date:  2004/10/23
      Time:  Just before sunset
      Wind:  Calm
   Vehicle:  SVC
     Scale:  41 %

Switched to LiPoly battery instead of NiMH from previous tests (see below).

Control was still a bit squirrely, but vehicle was much easier to control than
previous flights, probably because wind was calm. Rate of climb was good.
Vehicle had persistent left turn tendency. Adding right trim helped somewhat,
but didn't get rid of the problem entirely. Right turns were possible but
difficult.

On one flight, it appeared as though the airplane could maintain a very high
angle of attack (at least 30 deg) at full power. In the future, we should
investigate using this capability for autonomous landing at IARC. This would
avoid the added weight and complexity of a parachute.

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Regarding the left turn problem -- after the test flights, I looked at the
center of mass, and also looked for wing warps. The center of mass was
slightly displaced to the left. Also, the wing seemed to have a warp that
could cause a left rolling moment. I corrected CM problem. Attempted to
correct wing warp by bending wing -- limited success.

Also, the wing outer panels had slightly assymmetric anhedral. I tried to
correct this problem by bending wing, but again with limited success.

BTW, the very high angle of attack on one flight might be related to the delta
wing configuration combined with the leading edge snags.

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                             BATTERY

                       Supplier:  WildRC.com
                      Chemistry:  LiPoly
                Number of cells:  2
                        Voltage:  7.4 V
                       Capacity:  950 mAh
                           Mass:  44 g
                Max charge rate:  1.0 A
             Max discharge rate:  4.0 A

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   Test ID:  5
      Date:  2004/10/24
      Time:  Early morning
      Wind:  Calm
   Vehicle:  SVC, SVC/PAD
     Scale:  41 %

Flew several flights. Still had left turn tendency, but not as bad as
yesterday. Control was still a bit squirrely, but was able to control
airplane.

Attached subscale PAD to airplane. Was able to control airplane, but lateral
control seems a bit worse than it was without the PAD. Rate of climb was good.

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After the flights, I enlarged the elevons by changing them to constant chord,
75 mm. The previous elevons were tapered, from 75 mm at the root to 55 mm at
the tip. Length was 207 mm. Each elevon was 135 cm^2, is now 155 cm^2. Area
ratio is 1.15. The change also moves the elevon centroids toward the
wingtips, so roll control is more sensitive.

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   Test ID:  6
      Date:  2004/10/24
      Time:  Just after sunset
      Wind:  Light breeze
   Vehicle:  SVC
     Scale:  41 %

I flight tested the new changes later in the day. Control was much better --
no problems steering both left and right.

Pilot error resulted in a hard landing, which possibly shifted the battery
and center of mass. On the next flight, the vehicle was hard to control and
had another hard landing. There was minor damage in both cases.

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   Test ID:  7
      Date:  2004/10/25
      Time:  0630
      Wind:  Calm
   Vehicle:  SVC/PAD
     Scale:  41 %

Flew one test flight. Control was good, rate of climb was good. Roll control
was effective, unlike XE2/PAD. Was able to turn both left and right.

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Notes:

[1] All testing was at Globe, Arizona. Frank Manning was the pilot.

[2] Acronyms:

           SVC:  SubVehicle Carrier
           PAD:  Precision Air Deployment vehicle
       SVC/PAD:  PAD mounted on SVC

[3] Larger picture of SVC, with Globe, Arizona in background. The vehicle
here is an earlier version of the SVC, with smaller elevons, smaller vertical
tails, and a slightly different fuselage shape.

[4] Original Globe Delta off-the-shelf design, from which the SVC was derived.

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Last updated 2004/11/14 FLM