DC-7 T-60 may have flown her firefighting last mission

Long time readers know that I have a fondness for the DC-7 tankers, having written numerous posts over the years, go here  and here to see all of my posts on DC-7 tankers. Erickson Aero Air has three DC-7's, T-60, T-62, and T-66 after acquiring Butler Aviation in 2012. I knew from social media and from reading Bill Gabbert's Fire Aviation that T-60 was slated to retire from aerial firefighting this year. I am not sure about the status of tankers 62 and 66. Perhaps they are already retired. So, I was not surprised when I read Bill Gabbert's October 22nd post, Tanker 60 retires from aerial firefighting.

Rest well tanker 60, you have flown well, doing valuable service for many years flying fires in support of firefighters on the ground. You have helped save lives. I am sorry that I never met you or your kin DC-7 tankers in person. Where ever you go next fly in favorable winds. 

Direct link to video on Youtube

Reflections on DC-7 Tanker 62

A little over 10 years ago, I had seen a few references on the internet to Douglas DC-7 aircraft that were (and still are) used as tankers. I had always been interested in the Douglas series of aircraft, so I asked an aviation historian friend and former tanker pilot if he could help me find more information on the DC-7 Tankers. To make a long story short, he introduced me to Larry Kraus over e-mail who was the Captain (Pilot-in-Command) of T-62, under contract with the State of Oregon. What followed was an e-mail correspondence lasting about six to eight months.



Through this e-mail correspondence, Larry, who had been the PIC of T-62 for some 20 years by this time, took me up close and personal inside the DC-7 through his photos and our correspondence. He showed me the controls of the aircraft, inside and out, including the controls for dropping retardant, see this article I wrote in December 2009 for the summary of the first series I wrote, up close and personal with a DC-7 tanker. That series included several articles with some of Larry's wonderful photos of T-62. I offer it as a reference for those of you who might be interested in spending some time learning about the DC-7 tanker. I believe that T-62 continues to fly under contract with the State of Oregon with a different PIC as I believe that Larry has since retired.

I am very grateful for the time that Larry spent with me over e-mail, I can adequately describe how much I learned from Larry. He was kind and patient, answering my many questions. Thank-you Larry! I am no longer in touch with Larry, but his words and photos have stayed with me over the years. I understand that each type of tanker will operate a differently, but he did give me a good introduction to what it is like to fly fires.

Of the many articles that I wrote about T-62 with Larry’s help, the one that I hope you look at is a series that I wrote in March 2010, DC-7 Tankers in Action. I had sent him a video of T-62 and her sister DC-7 Tanker, T-66.  Larry took some time, checking his logs and some photos from a lead plane, to describe what we were seeing in the video, where he annotated some of these photos. The result was this series on DC-& Tankers in Action. But first please take a couple of minutes to read this article where Larry described how he worked with a lead plane

DC-7: present and 61 years ago

On a snowy March day in New Jersey I want to pause a bit and share two videos about the DC-7.

I came across the one below today and don't quite remember if I have seen this one before. If I have shared this one before, well enjoy the re-run. You will see DC-7 Tanker-66 on a take off roll in 2012 before Butler was acquired by Erickson Aero.


direct link to video

While I was looking at this video on youtube earlier today, I found this video from 1954 starring one of American Airlines DC-7 on a NY to Los Angeles flight. Allow about 29 minutes to watch this video. Thanks to Classic Airliners and Pop Culture for finding and sharing this video.


direct link to video

Braynt Fire (OR) - Tanker activity

Some of you will recall that from the end of 2009 into the first 2010, I wrote several articles on DC-7 tanker 62 thanks to the help of her Captain, Larry Kraus (Thanks Larry!) and several more articles with photos or videos on DC-7 tankers in action may be found here. You could say that I have a special fondness of the DC-7 tankers so I am always on the look out for any news about the sevens, especially T-62.

Over the weekend I first heard about the Bryant Fire (inch web), started on Thursday, June 19 that has burned 1,361 acres and is at 45 percent containment as I write this. You might also want to read updates on the Bryant Fire from the Oregon Dept. of Forestry (ODF), where the latest ODF update was posted at 8AM PDT on June 23.

Around the same time, I heard from a couple of reliable sources that T-62 had flown the Bryant Fire. I have no specific information to link to regarding tanker 62's activities on the fire. But I do know from reading the ODF June 22 blog entry about tanker and helo activity over the Bryant Fire on Saturday, June 21st:

sixteen loads of retardant were dropped from large air tankers and eight loads were dropped from small Single Engine Airtankers known as SEATs. Helicopters were extremely busy all day long responding to fire fighters requests for drops on the hottest spots.

The inciweb photo page for the Bryant Fire has a couple of photos of Neptune's BAe-146 T-10 dropping on the fire.

Here are a couple of articles on the Bryant Fire from local media outlets:

• OregonLive (June21st)
• Statesman Journal (June 23rd)
• Oregon Live (June 23rd)

Other Links

• Wildfire Today on Bryant Fire
• Wildland Fire Hotlist QandA on Bryant Fire
• Wildland Fire Hotlist Initial Attack Thread on Bryant Fire

Two Dougs taking off to fight fires (one retired, one still flying)

Conair DC-6 T-50 taking off from Dawson City. I believe that the last season that Conair flew DC-6 air tankers was in 1998. (To read a little about the history of Conair, including the DC-6 tankers they flew from the 1970s into the late 1990s see History of Aviation in the BC Forest Service, Part 2 Air Tanker Operations. The reference for 1998 being the last year that Conair flew the DC-6 on contract for the B.C. Forest Service is found on p. 24).  All three parts of the History of Aviation in the BC Forest Service may be found on this webpage of the BC Forest Service Centenary.

direct link to video

DC-7 T-60 taking off to fight a fire near Hood River, OR when she was owned by Butler Aircraft. As you may recall Aero Air bought Butler in December 2012 (see this article on Fire Aviation for more information).

direct link to video

DC-7 revisited

I ran across the video from the Experimental Aircraft Association (EAA) a few days ago thanks to a friend. EAA has an extensive collection of videos that you may look at on their video site. One of these videos is about Sully and Skiles obtaining their second in command rating for the DC-7 (in the EAA learning to fly channel), a direct link to the video may be found here.

Some of you may recall that I had the privilege of corresponding with Captain Larry Kraus, pilot in command of Butler Aircraft's DC-7 tanker 62 a couple of years ago. I learned a lot about DC-7 tankers and the tanker biz from this correspondence which I wrote about on this blog. See for example, this article, the first of many where I introduce the DC-7 and Butler's DC-7s. Those of you who may want to read more about the DC-7 tankers may want to start by reading articles with the DC-7 label (the newest article is listed first and if you go to the bottom of the page and click older articles you will see the earliest article).

Enjoy and Happy St. Patrick's day everyone!

more on emergency retardant drops

I recently wrote about emergency retardant drops here. I was going through some files on my computer earlier today and saw a draft of an article that I wrote in Dec. 2009, one of a series of articles on the DC-7 tanker. Most of the articles that I posted in December 2009, were on DC-7 air tankers, so here is a link if you are interested in the entire series. The article that interested me today is called Up close and personal with DC-7 tankers: retardant drops pt 2 of 2, written on Dec. 18, 2009. In this article, Larry Kraus, pilot of DC-7 tanker 62 speaks about emergency retardant drops. I am reposting the entire article here because of its relevance to my recent post. Enjoy!

Up close and personal with DC-7 tankers: retardant drops (pt 2 of 2)
Originally posted on Dec. 18, 2009 Random Ramblings: Aerial Wildland Firefighting Blog.

In my last post, I was writing about the Aero Union multi-door tank system (8 doors) used by Butler's DC-7's. I'll let Larry explain to you the sequence he goes through making a typical retardant drop:

To drop a full load at Coverage Level 6, I would have the co-pilot arm the tank system, and I would set the intervelometer to the 12 o'clock position (1), set the timer to 0.4 and set the doors to open selector to 8. Assuming that we'd gone through the Descent Check List while descending into the drop pattern I should be set. All that I have to do next is to determine the correct place to begin the drop and hold down the drop button (located on the yoke) until all of the doors open.

I know that there are times when tanker pilots must make an emergency drop of a retardant load. If an emergency happens near a tanker base, there is usually a designated place, e.g. coordinates, where emergency drops can be made. Otherwise, the pilot tries to look for a safe place -- no houses, no people on the ground, away from water sources, etc. -- to make the emergency drop. As I understand it, if a tanker pilot were to drop the entire load at once (aka a salvo) while making an emergency drop, the nose will do a sudden pitch up because of the sudden loss of 27,000 pounds of retardant. Often the pilots have a few hairy moments when this happens as they bring the tanker under control.

In the case of the DC-7, Larry tells me that emergency dump switch (outlined in blue in the photo) is centrally located on the cockpit panel. When Larry or his co-pilot lift the guard and activate the system by flipping the switch to the up position, the doors open at an approximate coverage level 5 drop. If I am thinking about this correctly, an added benefit is that an emergency drop at an approximate coverage level of 5 means that any pitch up of the nose of the tanker will not be nearly as bad as a sudden salvo of all doors at coverage level 8 (or higher). Larry provides some more details on emergency drops:

As far as having to jettison retardant in an emergency, it all depends on the severity of the emergency, the location and other local circumstances. In most cases, such as an engine failure deep in a canyon, there will be time for some quick (maybe 15-30 seconds) of trouble-shooting followed by determining if there is time (and the terrain allows) to fly to a suitable drop area. If we really are deep in a canyon, a suitable drop area will be anyplace nearby that doesn't contain a water source, people, vehicles or structures.

Again, it all depends on the circumstances. Generally, it will be possible to fly a few miles to an open area, but it's better for a spot on the ground to be covered with retardant than the flaming wreckage of an airplane. It would be unlikely that we would climb out of a canyon with 3 engines to carry the load to a designated jettison area. However, if the failure occurred enroute to the fire at altitude, that could be an option. There are also other emergencies not involving engines. Hydraulic problems being high on the list. I also once had a failure causing the loss of the fabric on the rudder on Tanker 62 during a drop run.

As I've mentioned before, nothing is ever easy in the tanker business.

DC-7 aircraft jacks (3 of 3)

Larry Kraus sent me some photos of T-62 over the Memorial Day weekend of T-62 undergoing maintenance in preparation for the summer fire season. Of interest are the very large (500-ton?) jacks used under the main landing gear and under each wings. Needless to say, these jacks are not carried on T-62!

DC-7: aircraft jack (2 0f 3) and self sufficiency

I continue where I left off in my preceding post where Larry Kraus was explaining to me about the tailwheel/nosewheel stand used by Butler's DC-7 airtankers. Larry describes this unique stand that he carries on his tanker (T-62):

If we didn't have this stand, we'd have to find a full sized jack to change the nose tire. It's actually pretty ingenious. It can be broken down into pieces and it weighs less than 70 lbs. I know this because we had to send one to Rapid City once by UPS Next Day Air when it was accidentally removed from T62 during maintenance and not returned and we had to change the nose tire.

For changing the main tires, a 30-ton hydraulic jack is used that is carried aboard T-62. According to Larry, the 30-ton hydraulic jack

fits under the center of the bottom of the main landing gear strut where there is a jacking point. Using the 30 ton jack we can change tires and brakes. We carry spare tires and spare brakes.

The spare tires (a nose tire and a main tire) as well as the spare inboard and outboard brakes act as both ballast and spares.We just have to carry the used tire and brake in the airplane as ballast until we can replace them with new ones. Getting the tire back in the airplane can be a challange without a fork lift. Getting the new one out of the airplane isn't easy either,but gravity works better going down than going up.

I don't have a photo of the 30-ton jack that is carried on T-62, but Larry found this 30-ton hydraulic jack on an internet search, which he says is similar to the one he carries on T-62:

He also sent this link, to ColumbusJack / Regent, a company that sells various aircraft axle jacks and related equipment.

In the photo of the jack adaptor that he uses as a tail stand and for the nose wheel jack, Larry has added a drawing in blue, showing where the 30-ton hydraulic jack fits in the picture.

Finally, Larry speaks of his need to be self sufficient:

Small general aviation airplanes wouldn't carry a jack around as they have no need to be self sufficient away from their home base. We pretty much have to carry any and all spare parts and tools with us. Most fixed base operators have no idea of our needs. Whenever we go to someplace that isn't used to our airplane and try to order oil they'll ask "How many quarts do you need?".....We work in drums....

You can figure our oil consumption as varying between about 2 and 5 gallons per hour per engine in a fire fighting operation. Multiply that by 8 hours for a full day and you'll see that, even at 2 gallons per engine per hour,we'd need 64 gallons of oil. We also carry a portable oil pumping system (with a small gas engine driven pump) that attaches to the top of an oil drum with appropriate fittings and has a 50 ft hose with a shut off nozzle.Again, getting the drum of oil into the airplane (it weighs about 350 lbs) is a challenge. On the Oregon contract, we can get by without carrying extra oil in the airplane because we only fly from bases that are set up for our operation.The engines have 46 gallon oil tanks.
I want to point out that I do not know what the other airtankers under national or state contracts carry with them.

DC-7 tanker: aircraft jacks (1 of 3)

Last December, I wrote a series of articles up close and personal with a DC-7 air tanker, thanks to the help of the pilot of T-62, Larry Kraus. A couple of months ago, Larry Kraus sent me a couple of pictures of (Butler's) T-66 as it was sitting on a ramp outside of Butler's maintenance hanger in Redmond with it's retardant tanks removed. According to Larry, the retardant tank was on a dolly in the maintenance hanger getting some repair work. These two photos are shown above. I looked at these photos and asked Larry what was hanging from T-66's tail.

This is Larry's reply:

It's a home made combination tail stand and nosewheel jack adapter.Sometimes when it snows heavily around here,enough weight in wet snow will accumulate on the horizontal stabilizers and elevators to cause the tail to squat down enough under the weight to lift the nosewheel off the ground. This is undesirable, especially if the wind is blowing.

So, with the tailstand in place, the tail can't settle enough (before the tailstand touches the ground) to lift the nosewheel clear.If you look closely at the pictures,you'll see holes in the vertical shaft of the tailstand and a metal pin inserted near the top.The shaft is actually two concentric shafts (a smaller diameter one inside the outer shaft) that can be adjusted to lengthen the shaft and the pinned to the new length by aligning the holes in the shafts.

Larry goes on to explain how this device is attached to the DC-7:

The "Y" shaped fixture that connects the tailstand to the hole in the tailskid (with another pin) is removable. The actual top of the shaft is concave to mate with a jacking adapter that's permanetly mounted on the airplane just aft of (behind) the nosewheel well on the belly of the airplane. 

In the photo below, Larry has put in a blue arrow showing the location of the nosewheel jackpad underneath the boarding ladder in the picture.

And Larry sent me a photo of T-66 as showing the repaired retardant tank just before it was put back in T-66. The retardant tank is below T-66 on the dolly.

Next up: more jacks used on the DC-7 tankers, changing tires, and self sufficiency

DC-7 tanker: revisiting ballast, weight and balance, and fuselage stations

Some of you may remember the series on the DC-7 tanker that I wrote last December, with the help and cooperation of Larry Kraus. Recall that Larry has been the pilot-in-command of T-62 for 27 years. One article in that series was an article that I wrote on ballast.

I am writing this article to follow-up on that article on ballast that I wrote last December with some information that Larry sent me in e-mail a few days ago. But first, let me review and summarize weight and balance.

All airplanes, large and small, have weight and balance limits that are set by the manufacturer and periodically checked by airframe and powertrain (A&P) mechanics. It is crucial that all airplanes must be within these weight and balance limits for safe flight. Every airplane has a center of gravity (CG), the point at which the plane is perfectly balanced. If you will, you could suspend the airplane from a string at the CG and the plane will be level. A plane with weight distributed too far forward will result in a nose down condition and if the weight is distributed too far aft (in the rear) will result in a nose up position. Both conditions can have fatal consequences for the crew.

In order to bring the airplane, in our case, the DC-7 tanker within her weight and balance limits, ballast is secured at carefully designated stations, known as fuselage stations. Fuselage stations are measured from a point known as a datum (aka fuselage station zero).

When I wrote the article on ballast as applies to the DC-7 tanker last December, Larry wanted to show  you a graphic from one of his DC-7 manuals showing the location of the datum and the fuselage stations in the DC-7 tanker. The problem at the time was that the manual that Larry needed was on a laptop that was comatose at the time, so he was unable to share the fuselage station diagram. The only manual that he had was a Douglas manual for a very early DC-6, showing the datum at a different location. Larry's comatose laptop revived, at least temporarily, a few days ago and Larry sent me a copy of the fuselage station diagram for the DC-7 tanker. You might want to click on the image below to enlarge the image for better viewing.

I'll let Larry explain:

It turns out that I was right about the location of fuselage station zero after all.I was sure that it was the front pressure bulkhead in front of the cockpit.As the radome nose on the DC-7 was an option and was several inches longer than the stock metal nose,I couldn't understand how the end of the nose could be the reference point.The early DC-6 must have been different than the later DC-6 and the DC-7.The DC-6 didn't add weather radar until later in production.The only reference picture that I had without the DC-7 manual was a Douglas manual for a very early DC-6.

Up close and personal with DC-7 tankers: reflections

See, I told you it is complicated, Nothing is ever easy in the tanker business. (Larry Kraus to K. Tyler Miller).

What can I say about this magnificent airplane, her pilots, co-pilots and all those behind the scenes who keep Butler's three DC-7 tankers in the air, flying fires? I can say that I feel an affinity for these tankers because of their original service as commercial airliners. I don't know if I ever flew on a DC-7, but I was a passenger on planes of a similar size and vintage. So, in some sense, even before I began the series on the DC-7, I had a relationship with these aircraft.

What I have gained from writing about these aircraft is a love for these three tankers. Three tankers that I call magnificent. It has been a joy to get to know these tankers up close and personal. I also know that these tankers are loved by their pilots, co-pilots, those in the shop who maintain the planes, and the ground crews. A bond between humans and aircraft that ensures that these fire engines in the sky are flying. A bond that ensures that some of us can get to know these magnificent aircraft up close and personal.

There is a another bond, that is the bond among fire fighters, both in the air and on the ground. I think of this bond as the raison d'etre. Larry speaks of this bond:

We have a bond with the other fire fighters that we work with, both in the air and on the ground. There is a mutual respect similar to that which develops in a military unit that has been in combat. It's always a pleasure to work with people who know their jobs. We all know that we can depend on each other and we do so every day. There's a great deal of satisfaction in being a useful part of that team.

Nothing is simple in the world of flying tankers, those fire engines in the sky. I have learned a lot in writing this series about the DC-7 including but not limited to weights and balances, a view inside the cockpit, quick engine changes (Q.E.C.), and multiple door retardant systems. These are important, but the most important point that I want to pass on to you is what Larry kept saying to me over and over in our e-mail correspondence:

See, I told you it is complicated, Nothing is ever easy in the tanker business.

Larry should know, he has been piloting DC-7 tankers for some 27 years.

Still to come on DC-7 tanker series

I took a short break for the Christmas holidays and will be finishing up my series, up close and personal with DC-7 tankers this Wednesday with my own reflections.

Up close and personal with DC-7 tankers: in action (2 of 2)

When I first wrote this entry in December 2009, there was a very nice 20 minute video on Patrick's Aviation from Bob Webb shot from the cockpit of a DC-7.  The Patrick's Aviation website has since been taken down. So I am embedding a couple of Bob Webb's You Tube videos shot from a DC-7 tanker.

I will never get a chance to ride in the cockpit of an air tanker, but thanks to Bob's videos, I can say that I have experienced what it is like to ride in the cockpit of an airtanker. Enjoy.

I will be posting my own reflections based on my experience writing this series on DC-7 tankers in a few days after the original date of the post (December 23, 2009).

Edited on November 8, 2016

Shot during the 2005 fire season, DC-7 Tanker. pilots are Webb/Rowe. 

Direct link to video by Bob Webb

Shot during the 2005 fire season southwest of Cedar City Utah, DC-7 Tanker. From Bob's description of the video: "flying down into a deep hole to get to the fire, not once but twice!"

Direct link to video by Bob Webb

Up close and personal with DC-7 tankers: in action (1 of 2)

Now for the fun stuff. Here is a sequence of photos (below) of Brian Lash and Rick Langstrom in Butler's tanker 66 on the Deer Ridge Fire near the Medford OR airport on or about September 22, 2009. Mike Bitney took these photos and sent them to Larry. It is a great sequence of photos. For those of you who are interested, here is a link to Warbird Information Exchange (WIX) where Larry posted these and other photos of tanker 66 and tanker 62 in action. There are some other nice action shots on this same WIX thread of tanker 62 in action in 2008 here.

I expect to make two more posts in this series of articles on DC-7 tankers, one more on DC-7 tankers fighting fires and a final post where I offer my own reflections. So, stay tuned. In the meantime, enjoy these photos.

So as not to confuse, the video is taken at Fox Field in Lancaster, CA (probably in 2007).

 

 

 

 

 

 

 

 

 

Up close and personal with DC-7 tankers: retardant drops pt 2 of 2

In my last post, I was writing about the Aero Union multi-door tank system (8 doors) used by Butler's DC-7's. I'll let Larry explain to you the sequence he goes through making a typical retardant drop:

To drop a full load at Coverage Level 6, I would have the co-pilot arm the tank system, and I would set the intervelometer to the 12 o'clock position (1), set the timer to 0.4 and set the doors to open selector to 8. Assuming that we'd gone through the Descent Check List while descending into the drop pattern I should be set. All that I have to do next is to determine the correct place to begin the drop and hold down the drop button (located on the yoke) until all of the doors open.

I know that there are times when tanker pilots must make an emergency drop of a retardant load. If an emergency happens near a tanker base, there is usually a designated place, e.g. coordinates, where emergency drops can be made. Otherwise, the pilot tries to look for a safe place -- no houses, no people on the ground, away from water sources, etc. -- to make the emergency drop. As I understand it, if a tanker pilot were to drop the entire load at once (aka a salvo) while making an emergency drop, the nose will do a sudden pitch up because of the sudden loss of 27,000 pounds of retardant. Often the pilots have a few hairy moments when this happens as they bring the tanker under control.

In the case of the DC-7, Larry tells me that emergency dump switch (outlined in blue in the photo) is centrally located on the cockpit panel. When Larry or his co-pilot lift the guard and activate the system by flipping the switch to the up position, the doors open at an approximate coverage level 5 drop. If I am thinking about this correctly, an added benefit is that an emergency drop at an approximate coverage level of 5 means that any pitch up of the nose of the tanker will not be nearly as bad as a sudden salvo of all doors at coverage level 8 (or higher). Larry provides some more details on emergency drops:

As far as having to jettison retardant in an emergency, it all depends on the severity of the emergency, the location and other local circumstances. In most cases, such as an engine failure deep in a canyon, there will be time for some quick (maybe 15-30 seconds) of trouble-shooting followed by determining if there is time (and the terrain allows) to fly to a suitable drop area. If we really are deep in a canyon, a suitable drop area will be anyplace nearby that doesn't contain a water source, people, vehicles or structures.

Again, it all depends on the circumstances. Generally, it will be possible to fly a few miles to an open area, but it's better for a spot on the ground to be covered with retardant than the flaming wreckage of an airplane. It would be unlikely that we would climb out of a canyon with 3 engines to carry the load to a designated jettison area. However, if the failure occurred enroute to the fire at altitude, that could be an option. There are also other emergencies not involving engines. Hydraulic problems being high on the list. I also once had a failure causing the loss of the fabric on the rudder on Tanker 62 during a drop run.

As I've mentioned before, nothing is ever easy in the tanker business.

Up close and personal with DC-7 tankers: retardant drops pt 1

The tank system used in the DC-7 is an Aero Union multi-door tank system with eight doors where each of the eight tanks holds 375 gallons.Up until now when I have written about retardant tank systems in use by firefighting aircraft (e.g. the Erickson AirCrane and the AT-802), I have written about constant flow tank systems with either one variable single door or multiple doors. As I understand it, both of these systems are controlled by computers. Where the PIC has only to set the desired coverage level and possible the quantity of retardant to be dropped. These systems are easier to use, but come at a price. According to Larry Kraus, an Aero Union constant flow variable single door system for the DC-7 would cost at least$250,000 (perhaps more), representing a significant hunk of change out of Butler's budget.

The panel shown in this photo is located on the co-pilots side of the cockpit. The red light over the drop arming switch marked "off" is constantly on until the tank is armed, in which case it goes off. By the way, this switch is configured the same way across all of Butler's DC-7 tankers. Moving on, the switch on the left side of the drop panel marked "Flow/High/Low has been disabled as they no longer use the flow feature.

 

The dial in the photo above is called an intervelometer. Larry uses this dial to set how many tanker doors open at once. In this photo, it is set to safe, meaning that the doors will not open, moving clockwise:

LFT is the four doors on the left opening at once,
RT is the four doors on the right, and
ALL is the salvo of all eight doors opening at once

Continuing clockwise, to open double doors at a time, the dial is set to 1-2, and to open a single door at a time, Larry sets the dial to 1.

Larry provided an interesting piece of history about the intervelometer: "As far as the intervelometer, it was a surplus military item, as were a number of parts in the Aero Union 8 door tank. It originally was used for selecting the firing sequence for air to ground rockets on fighter bombers."

 We are not done yet, there are two more dials Larry uses, one sets the interval between door openings in tenths of second when pilot-in-command (Larry) presses the drop button that is located on the top left side of the yoke. The second dial sets the total number of doors to open. Larry explains the settings in this picture:

"In this picture,they are set to 0.4 seconds and 8 doors. At 130 kts. and 150 ft. above the terrain, with the intervelometer set for single doors, I would get approximately a coverage Level 6, or 6 gallons of retardant every 100 square feet (a 10 ft by 10 ft area) on the ground."

On Friday, I'll be writing more about retardant drops, so stay tuned!

Up close and personal with DC-7 tankers: the cockpit

I don’t know about you, but I have always been interested in airplane cockpits. When I have flown on commercial flights, I often will sneak a pike in the cockpit as I am boarding the flight. My intent here is to present some of Larry’s photographs of the cockpit of his tanker, T-62, along with some selected DC-7 manual pages that Larry had on file in his working computer.

What I have done, with Larry’s assistance, is to take the graphic and numeric key of a typical DC-7 cockpit arrangement (prior to conversion to its current use as a tanker) and match up some of Larry’s cockpit photos with the numeric key for the graphic of the cockpit arrangement. First I present the two images of the cockpit arrangement graphics then I present his pictures.

Please don't forget to read the comment after the pictures.

 

 

cockpit (radio stack on left in foreground)

control pedestal (36)

control pedestal (36)

control pedestal (36)

pilot-in-command instrument panel (25)

engine instrument panel (26, above control pedestal)

co-pilot instrument panel (27)

main fire control panel (in 16, above engine control panel)

heater fire panel (2)

upper instrument panel (8)

forward overhead panel (3)

aft overhead panel (1)

As Larry told me recently, "see, I told you it was complicated!"

Up close and personal with DC-7 tankers: former passenger cabin, floating beam

Before going any further, it is very important for you to know that this photograph of the passenger cabin of tanker 62 was taken before the ballast items were loaded.

Ok, moving on, do you notice the box like structure running across the cabin floor? That is, according to Larry, the floating beam. The floating beam secures the retardant tank to the aircraft. But Larry says that it is another important purpose, it helps to distribute the "considerable weight of the retardant tank (1,500 lbs.) and the retardant (27,000 lbs.) across the front and rear wing spars." Larry told me later that the floating beam acts like a shock absorber. As I understand it, by acting like a shock absorber, the floating beam will absorb the shock as the tanker is taking off, flying, and landing.

Not only is the retardant tank, located below the floor of the passenger cabin (in the belly of the tanker), attached by means of the floating beam, there are attach points fore and aft. Larry explains:

Along with the floating beam, the tank has attachments at the forward and aft ends as well. The four attach points at the floating beam distribute the majority of the weight of the tank and retardant to the wing spars, but there are also two attach points near the front of the tank on top near the outboard corners.

These attach to a reinforced area of the fuselage where the forward baggage compartment and the hydraulic compartments meet in a bulkhead. There are two similar mounting attach points at the other end of the tank where the rear baggage compartment meets the heater and air conditioning compartments  All of these are belly compartments below the floor of the passenger compartment.

These mounting attach points don't have the shock absorbing qualities of the floating beam and I've seen individual mounting bolts break on a couple of occasions. Nothing serious, but on a preflight check you can see the tank sag near the broken bolt when it's loaded. On the plus side, I haven't seen one break in the last 15 years.

Up close and personal with DC-7 tankers: former passenger cabin, ballast

 The image above is interesting to me for a couple of reasons. First, remember that Butler's DC-7's once saw service with the airlines. Obviously, part of the conversion process from passenger plane to tanker has been stripping the old passenger cabin. Moving on. Now in this photo it is obvious that there is something going on. This is Butler's tanker 66 and the gentlemen in the photo is Brian Lash, the pilot of T-66. Larry Kraus tells me that in this photo, taken on May 26, 2008, Brian is doing a preflight check for a maintenance test flight of T-66. More importantly, Larry sent me this picture because it shows ballast secured in place on the aircraft.

Ballast represents additional items (for example the tires in back of the cabin in the above photo), is carefully stowed and secured at specific points called fuselage stations to add weight to bring the aircraft within manufacturer designated weight and balance parameters. It isn't just the weight of the plane that is important but how the weight is distributed within the plane that is crucial for safe operations. For example, weight that is distributed too far forward will put the plane into a nose down situation with possible fatal consequences for the plane and crew. Aviation mechanics, aka airframe and power train or A&P mechanics, periodically reweigh the plane and then check the planes center of gravity. Once the center of gravity is known, there are calculations that are performed that determine weight and balance parameters. Then additional ballast is often needed to bring the plane within these weight and balance parameters.

The photo above, a little fuzzy, shows one of these fuselage stations (F.S. 860) for tanker 62. What this means, according to Larry, is that this station is "860 inches aft of the weight and balance datum (F.S. 0, located at the tip of nose of the DC-7)." As I understand the weight and balance datum is also known as reference datum and is:

an imaginary vertical plane from which all horizontal distances are measured for balance purpose (FAA, Aircraft Weight and Balance Handbook (2007), Glossary p. 5).

From this ballast station, F.S. 860, additional ballast stations (fuselage stations) and their assigned weights are calculated to assure that tires, parts, ladders, etc equal the required ballast. According to Larry T-62 carries somewhere around 1200 lbs. of ballast. Most of it is behind (aft) of F.S. 860 and some of it is forward of F.S. 860.

Larry wanted to show you a graphic from one of his DC-7 manuals (electronic files) showing the location of the fuselage stations. Unfortunately, computer troubles with the computer where these manuals are stored prohibit him from doing so. Thanks for the effort, Larry.

I want to close this article on ballast by letting Larry share with us about how the weight of the retardant tank (1,500 pounds empty and an additional 27,000 pounds when carrying 3,000 gallons of retardant) affects tanker 62's center of gravity (CG).

With the retardant tank installed, the DC-7 is out of the forward center of gravity range in the empty condition unless several hundred pounds of ballast is located right aft, or a higher total weight spread over the aft part of the fuselage. We originally used sandbags at the rear pressure bulkhead,which is as far back as you can go inside the pressurized cabin, just behind the seats in the old passenger lounge at the rear of the plane.

The weight varies from airplane to airplane. I think that it's around 660 lbs on tanker 62.We now carry spare tires.tools,parts and other supplies that are carefully weighed in place with the fuselage stations noted (in inches from the bulkhead forward of the cockpit) to be sure that we get it right.

The mechanics changed things around in T-62 this year after doing a new weight and balance and I think that they got the CG slightly too far forward. At least it felt that way on take-offs and landings.There's a heavy box that we can move fore and aft over several feet to easily adjust the CG, but it wasn't bad enough to adjust, although I thought about moving it a couple of feet aft to see if I was right, but the season ended before I got around to moving it.

References

A wikipedia entry on an aircrafts center of gravity and the related concept of weight and balance may be found here. A somewhat more technical publication (cited above) called the Aircraft Weight and Balance Handbook (2007) is published by the FAA and freely available on the web, Much of it is written for A&P mechanics and other aviation experts. But the first chapter or two have an overview that I could follow as well as a glossary.