DC-Tankers in Action (part 4)

Continuing with the Dixie Gulch Fire, these stills are captured by Larry Kraus from video shot by Bruce Smith (Air Attack) from the back of the ASM assigned to the fire.  According to Larry, the drop shown in this series of stills is the same drop as shown in the you tube video that I posted on March 4 and again on March 5.

With this article, I finish with the Dixie Gulch Fire. I will be finish this series on DC-7 Tankers in Action with my next post.

 

  

  

  

 

DC-7 Tankers in Action (part 3C)

I conclude this set of three posts of tanker 66 at Dixie Gulch with two stills taken after the drop in the previous article (part 3B). Recall that these stills were captured by Larry Kraus from video shot by Bruce Smith.

Larry wanted you to see these because they show the little airport's (Springbrook) location in relation to the fire. Larry sent along the image from Google Earth where he circled the location of the Dixie Gulch fire shown in the you tube video that I posted on March 5.

DC-7 Tankers in Action (part 3B)

I continue with three stills, again captured by Larry Kraus from video shot by Bruce Smith, of Tanker 66 making drops on the Dixie Gulch Fire. Larry thinks that these three stills are from the drop in the you tube video I posted on March 4 and again on March 5.

 

  

 

DC-7 Tankers in Action (part 3A)

I continue with these articles on DC-7 tankers in action, focusing on the youtube video (from the Dixie Gulch Fire) that I posted on March 4 and again on March 5. I continue today with three posts (part 3A, part 3B, and part 3C) with some stills captured by Larry Kraus from video shot by Bruce Smith (Air Attack) from the back of the ASM assigned to the fire.

Larry says that these two pictures show

tanker 66 dropping a couple of doors as the second run with his first load on the Dixie Gulch Fire.

Note what appears to be the small airport in the second photo.

 

 

DC-7 Tankers in Action (part 2)

Larry found his logs from the day of the fire in the video that I will share with you in a moment. But first, a word on (DC-7) T-66. The pilot-in command of T-66 is Brian Lash. Now it was Brian's day off on the day of the Dixie Gulch Fire, so the pilot of T-66 that day was Gene Teske flying with Rick Langstrom (Brian's co-pilot).

Here are the pertinent entries from Larry's log for Sunday the 13th:

Took 2 loads to the Dixie Gulch Fire-Near the fire from yesterday-Coverage 8 full load twice-Went well with ASM A4- T66 came in from Redmond for 2 loads (Gene Tesko/Rick Langstrom)-Later T10 (Chris Holm) and T05 (Skip) loaded at Medford for fires by Klamath Falls-First T66 had to move out of loading pit-Later T62 had to move (with Medford Air's tug to Ericson ramp))-Fly T62 for 45 minutes total-

Larry provides some more specific information about how he was flying T-62 during the drop shown in the video. But first, I went to pause and spend a little time with some terminology that Larry will be using. Flaps are on the wings of most aircraft, we'll get to them in a little more detail in a minute. BMEP refers to power settings of the engines. In this case, the tachometers on the DC-7 indicate engine rpm. Larry spent a little time the other day providing some more details on these terms as applies to his DC-7, T-62:

As to BMEP, about the best explanation that I can give is that it gives a real-time accurate indication in the cockpit of the horsepower being developed by the engines.

On the DC-7 the tachometers actually indicate the engine rpm. The reduction gears in the engine nosecase reduce the propeller rpm by a factor of 16:9, so the prop turns at a bit over half of the engine RPM. This is partially because the prop tips become supersonic above these reduced speeds and drastically lose efficiency. If my math works, the prop speed on take-off is 1631 rpm with the engine rpm of 2900. This is still a rather impressive 27 revolutions per second for the prop and 48 for the engine.

Wing flaps allow the wing area and camber (curvature) to be altered to make it more efficient for either high or low speed flight. For take-off, the DC-7 uses 20 degrees of flap. The wing flaps extend aft increasing the wing area and deflect downward at a 20 degree angle to increase the camber of the wing.Once the landing gear has been retracted and the airplane has gained enough altitude to safely allow for any settling resulting from the loss of lift, the flaps are fully retracted to allow an increase in speed.

Larry sent along two pictures of T-62, one with the flaps extended and the other with the flaps retracted.

Larry goes on:

With the flaps retracted (to zero degrees) there is slightly less wing area and the wing has less camber which allow for higher speed mainly due to less drag. For landing or the final part of the drop pattern we end up with the flaps fully extended to 50 degrees. This is a high drag position that helps to control the airplane's speed. With the flaps on the DC-7, the first 20 degrees is all lift, 30 degrees is slightly more lift, but with some additional drag. Above 30 degrees any increases in flap angle are mostly drag.

For those of you who are interested in some more specifics on the flaps of the the DC-7, Larry says that

the flaps on the DC-7 are double slotted flaps, but the upper slots on the DC-7 are just airfoil shaped deflectors that are the full span of the flaps, but only have a chord of about a foot. In the picture of a double slotted flap from how stuff works, the slots are larger than the rest of the flap.
Here are two links that Larry sent me to share for those of you who want more information about how flaps work, one is from Wikipedia and the second is from How Stuff Works.

With this as background, Larry continues with how he is flying T-62 during the drop in the video:

I had full flaps (50 degrees) out during the part of the drop pattern that is in the video. At least I have full flaps until the retardant starts coming out at which time we normally retract the flaps to 20 degrees (the take-off setting) and go to climb power which is 175 BMEP and 2400 RPM for the recovery and climb out.

In the final part of the pattern we usually have 2400 RPM set and are throttled back to as low as 100 BMEP, which is the minimum that we can set without driving the engine with the prop instead of the other way around. Normally, in the drop pattern, we start out with 20 flaps and 2400 RPM and 130-140 BMEP in order to stabilize at around 140 kts. On downwind for the drop we'll go to 30 flaps and 130 BMEP and maintain between 130-140 kts.Somewhere around base for the drop we'll go to full flaps and whatever power is required to maintain 130 kts.

When I start dropping the retardant I'll call for Climb Power and Flaps 20. This allows the airplane to accelerate without losing lift too quickly. If I need to make an immediate turn or clear a ridge or both, we'll go to climb power and leave full flaps until we can afford to have the airplane settle a bit with flap retraction. It all depends on the situation at the time.

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