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Thursday, March 04, 2010

DC-7 tankers in action (part 1)



This is a video that I found on youtube a few weeks ago, I sent Larry Kraus the link and we have been chatting about this video over e-mail. This is the first of three or four articles where, with Larry's help, I spend a little time on what is going in this video.

Before I go any further, as you watch the video you will see a drop by T-66 (also a Butler DC-7 tanker), followed by a drop by Larry in T-62, then a drop by T-66, and finally another drop by T-62. I watched the video a few times and thought that the T-62 footage might be the same drop, so I asked him about this. He says,

I came to the same conclusion on the video showing a single drop for each airplane taken from slightly different camera positions.

Larry spent a little time going through his data and logbooks to identify the fire shown in the video. He sent me the following graphic of a TFR (temporary flight restriction) for a group of fires known as the Queen's Branch Complex, saying"

I attached the TFR map for the Queen's Branch Complex of small lightning caused fires near Medford, Oregon. This might be where the video was shot. The only thing that's confusing to me is that there's no sign in the video of the Alaska ASM that was acting as leadplane, but I suppose that it might have been edited out. If it was edited, that's a shame as it would be even more interesting with the lead.

I will go into some more detail in a later post about how Larry identified that the fire in the video is the Dixie Gulch Fire. For now, take a close look at the TFR graphic, you will see a small airport -- Springbrook -- within the TFR. The Dixie Gulch Fire was located not far from the Springbrook Airport. The key, as Larry told me, is the word

"complex" which indicates several fires being included within the confines of the TFR. The Queen's Branch Fire was the first fire responded to and it's name was used for the TFR.

Larry talks about maneuvering T-62 while making a retardant drop:

As to maneuvering the DC-7 around during drop patterns, there are a few things that must be done. The first is that I have to keep glancing at the airspeed indicator every couple of seconds and my co-pilot (Ron Carpinella in the video) knows to tell me if we get down to 120 kts indicated airspeed if I haven't told him that I was purposely slowing the airplane. Also, the DC-7 has an excellent aerodynamic stall warning in the form of a buffeting that starts in the control yoke at about 5 kts above the stall. If you don't release back pressure or reduce the bank angle when this "nibbling" starts, the whole airplane shakes violently enough to about shake your teeth loose prior to the wing actually stalling.

In the video, I think that you will notice that I keep the nose down during the turns and I'm still about 15 kts above stall speed even after tightening the turn. Part of tanker flying includes leaving yourself an escape route to lower terrain if something starts to go wrong. I try to brief my co-pilot on where that escape route is before we start a run. Of course, it isn't always possible to find good routes to lower terrain, so I keep the best available escape path in mind on all drop runs.

The B-17 was a good trainer for that as you couldn't climb out of most situations and had to plan an escape route that was sometimes a couple of miles long. It also gave me a built in awareness of which way was eventually downhill. For several years in the 1970's, I drove a 1964 VW van with a 40 hp engine. I semi-joked that the VW van and the B-17 were very similar as with either one, you always knew which way was uphill and which way the wind was blowing.

One other item on the video is that the camera angle makes T62 look lower in relation to the terrain that it actually is. That said, we do get low and slow (think 130 kts and 150 ft while loaded) and have to maneuver in tight places close to the ground in areas where the visibility can go to zero for several seconds at a time in smoke. As I've mentioned before,the tanker business is complicated and nothing is ever easy.

I asked him about dropping the nose during his turns, he explains:
As far as keeping the nose down in turns in the DC-7. All of the Douglas 4 (piston) engine transports tend to slow quickly if you let the nose come up with a lot of flap deployed. The approach angle for landing is decidedly nose down in these airplanes and a pilot's natural tendency is to let the nose come back up toward the horizon. You have to learn to fight that tendency when flying these airplanes in either the landing or drop configuration.You are also correct in assuming that keeping the nose down in the turns gives an added buffer against a stall.

We will hear from Larry tomorrow on his drop at this fire. Stay tuned!

Other articles in this series (March 5 to March 12, 2010)

DC-7 Tanker in Action (part 2)
DC-7 Tanker in Action (part 3A)
DC-7 Tanker in Action (part 3B)
DC-7 Tanker in Action (part 3C)
DC-7 Tanker in Action (part 4)
DC-7 Tanker in Action (part 5A), Mud Mountain Fire
DC-7 Tanker in Action (part 5B), Mud Mountain Fire

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