The RQ-170 is how small? tiny! , page 1

Here is my latest analysis on size of the airframe:

I looked into the Michael Yon image a little further and noticed the holding position sign labeled "5-23" in the background, just aft of the port wingtip of the RQ-170. I looked into signage specs online and found the following link:

Planning and Design of Airports by Robert Horonjeff - Page 338

The table states the sign legend (i.e. inscription) can be 15 to 18 inches in height, depending on the "effectiveness, aircraft clearance, jet blast and snow removal" (per the referenced book). We can assume, since the sign is behind the RQ-170, it can be used as a reasonable scale to measure the distances on the airframe.

If the distance from the camera to the RQ-170 is much greater than from the RQ-170 to the sign, then it is reasonable and can be proven with a little geometric analysis. In reality, the aircraft will measure smaller than if the signage height is used as the measuring unit. Also, per the link below, a standard taxiway light stands 14 in:

GSI-LED-861-T

I downloaded the original Michael Yon image from flickr:

Then overlaid it in MS PowerPoint and, leaving the original aspect ratio alone, resized it at 9.0 in by 6.0 in. I overlaid a rectangular shape and found the holding position sign font to be 0.095 in (it is to be at least 15 in tall, per the book). I also found the taxiway light in the near field to measure 0.48 in (it is 14 in per the GSI link). This allowed me to measure the RQ-170:

Height = 0.60 in
Tip to Tip = 3.96 in
Starboard = 0.82 in
Port = 3.14 in

So drawing lines from the near to the far field heights of 14 inches, and pick 2/3 of the way from the taxiway light to the holding position sign, we get a scale of about 82:1 for an image that is 9.0 in by 6.0 in.

Height = 49.4 in = 4.1 ft
Tip to Tip = 325.9 in = 27.2 ft (at this offset angle we are looking from)
Starboard = 67.5 in = 5.6 ft
Port = 258.4 in = 21.5 ft

I also ran a cosine table (of offset angle) of estimated wing spans, varying the offset angle we are viewing the RQ-170 off it's centerline. As a result, I'm estimating the following wing spans:

View Angle [deg] = Wing Span [ft]
30 deg = 31.4 ft
45 deg = 38.4 ft
60 deg = 54.3 ft

My best estimate is that we're viewing a little more than 45 deg, but less than 60 deg, putting the wing span at around 46 ft. I believe Bill Sweetman's estimates are over 75 ft, however I tend to agree with Astr0 and believe it is significantly smaller than first thought.

Another element to consider is they're likely running a Williams International FJ-44-X core turbofan and these engines are not that powerful, thus supporting the smaller airframe theory. If you look at the FJ-44-4, the thrust rating for an uninstalled single engine runs 3,600 lb. With a fairly conservative T/W ratio of 0.35 and an inlet installation loss of 25% (you'll likely see more due to the grid inlet and extreme flow turning angle at higher total AoA), you get a TOGW around 7,700 lb which is small. RQ-3A TOGW was 8,500 lb.

edit on 14-12-2010 by TAGBOARD because: (no reason given)