B25 Miss Mitchell first bomb drop since WW2-video

[turret nate]

The CAF Minnesota wing has completed the restoration of the bomb bay in B25J Miss Mitchell. A big thanks to Taigh Ramey for his help in teaching me how the system works. The last step is to integrate the Norden and intervelometer – right now the system is working on the “pickle” on the bomb release panel.

Here is the video: http://www.youtube.com/watch?v=FVWmnpnRRaY

I have some other videos on that youtube channel of Miss Mitchell's operating Bendix upper turret and Bell tail turret.

Maybe we can hook up with the Tora Tora Tora crew if they are in the midwest, and drop some dummy bombs combined with ground pyro?

[The Inspector]

[gary1954]

The CAF Minnesota wing has completed the restoration of the bomb bay in B25J Miss Mitchell. A big thanks to Taigh Ramey for his help in teaching me how the system works. The last step is to integrate the Norden and intervelometer – right now the system is working on the “pickle” on the bomb release panel.

Here is the video: http://www.youtube.com/watch?v=FVWmnpnRRaY

I have some other videos on that youtube channel of Miss Mitchell's operating Bendix upper turret and Bell tail turret.

Maybe we can hook up with the Tora Tora Tora crew if they are in the midwest, and drop some dummy bombs combined with ground pyro?

That is awesome!!

[SaxMan]

That is just too cool.

[Travisd80elcam]

This is awesome, but it makes me think that y'all need a farmers field to drop some dummy bombs in

Travis

[Taigh Ramey]

I am so proud of you! sniff sniff... I am glad I could have helped. Well done!

Now get her up in the air for a drop from altitude. Unfortunately those practice bombs are pretty spendy to drop so you should make a mold of a 100, 250 or 500 pound GP and cast them up from concrete like we are doing. They are a lot cheaper to drop.

When I was dropping from the Beech AT-11 many years ago I used the metal sand and water filled 100 pound Mk15's as they were cheap. I could use them for about 5 to 10 drops until they were too bent up to use again. The fins would get tweaked and they never flew as straight as the first time. The drop speed in the Beech was 160 mph. When we dropped from the B-25 the higher speed (200 mph) was too much and the sheet metal bombs were not so re-usable.

Here is a video of dropping from the B-25 Old Glory at Eagle Field: http://www.youtube.com/watch?v=ztPRk-Pejlc

You can see the bombs skipping along as they hit fairly flat at the low level. We actually took out a jack rabbit on this drop. It was found under the bomb. Probably didn't see it coming but if he did he probably just didn't believe what he was seeing! yes, the rabbit died...

Here is a video from the first Bomber Camp in the B-24 with the 250 pound concrete bombs. These burrowed in about 10 feet in nice perfectly round bore holes. The fins shredded off of course but the bombs could actually be used again if we had wanted. We drop at a different range now and the ground is real hard and the bombs turn to dust and just leave a dent in the ground.

http://www.youtube.com/watch?v=3ueUJPqWWbY

This year we are going to drop from the B-17 so come on out and sign up for bomber camp. I am running the Norden so if someone wants to receive some actual Norden dual instruction and drop 250 pound GP's from the nose of the B-17G then sign up for bomber camp at the end of May in Stockton.

Remember that the FAA says that if it is installed it should be operational and we certainly do not want any unsightly INOPERATIVE placards in our warbirds so, as conscientious mechanics, we are duty bound to make sure all of the turrets, bomb racks and radios operational!

Once again Well done Nate. You are really gonna love how the intervalometer works in the system. It is a hoot and also a real eye opener to how fast you can clear the bomb bay.

Keep up the good work!

Taigh

[turret nate]

Love that B24 video Taigh, great work. The ground video taken near that truck, with the noise from the inbound bombs is way cool. I found that video on Youtube a few years ago, it was actually what inspired me to get our bomb bay working.

I am glad you mentioned the dummy bomb thing. We were just talking about how we could do that, especially if we integrate drops into air shows. We may end up having to make alot of dummy bombs if it becomes popular. When you mold bombs out of concrete, I assume the tail is still sheet metal? Is there a commercial source for the rear section or are you making those?

The bay is spaced right now for twelve 100 pounders so we are planning on going with that set up.

[tom d. friedman]

I am so proud of you! sniff sniff... I am glad I could have helped. Well done!

Now get her up in the air for a drop from altitude. Unfortunately those practice bombs are pretty spendy to drop so you should make a mold of a 100, 250 or 500 pound GP and cast them up from concrete like we are doing. They are a lot cheaper to drop.

When I was dropping from the Beech AT-11 many years ago I used the metal sand and water filled 100 pound Mk15's as they were cheap. I could use them for about 5 to 10 drops until they were too bent up to use again. The fins would get tweaked and they never flew as straight as the first time. The drop speed in the Beech was 160 mph. When we dropped from the B-25 the higher speed (200 mph) was too much and the sheet metal bombs were not so re-usable.

Here is a video of dropping from the B-25 Old Glory at Eagle Field: http://www.youtube.com/watch?v=ztPRk-Pejlc

You can see the bombs skipping along as they hit fairly flat at the low level. We actually took out a jack rabbit on this drop. It was found under the bomb. Probably didn't see it coming but if he did he probably just didn't believe what he was seeing! yes, the rabbit died...




the old tall tale of the norden bombsight's bragged about ability should be changed from dropping a bomb in a pickle barrel to clobbering a jack rabbit!!







Here is a video from the first Bomber Camp in the B-24 with the 250 pound concrete bombs. These burrowed in about 10 feet in nice perfectly round bore holes. The fins shredded off of course but the bombs could actually be used again if we had wanted. We drop at a different range now and the ground is real hard and the bombs turn to dust and just leave a dent in the ground.

http://www.youtube.com/watch?v=3ueUJPqWWbY

This year we are going to drop from the B-17 so come on out and sign up for bomber camp. I am running the Norden so if someone wants to receive some actual Norden dual instruction and drop 250 pound GP's from the nose of the B-17G then sign up for bomber camp at the end of May in Stockton.

Remember that the FAA says that if it is installed it should be operational and we certainly do not want any unsightly INOPERATIVE placards in our warbirds so, as conscientious mechanics, we are duty bound to make sure all of the turrets, bomb racks and radios operational!

Once again Well done Nate. You are really gonna love how the intervalometer works in the system. It is a hoot and also a real eye opener to how fast you can clear the bomb bay.

Keep up the good work!

Taigh

[turret nate]

Taigh, I am hoping to get some more advice. I completed hooking up the intervelometer and norden today.

For the Intervelometer, the light activates and it begins to click down at the selected rate when (1) the pickle is pressed and held down or (2) the norden firing contacts close. However, as the unit clicks down no A4s release (I do have the selector set on TRAIN). What am I missing?

For the norden, I seems to have a seized rate and displacement knob. The outer knob is very stiff and hard to turn, while the inside knob moves fairly freely - moving one of the two index window/ firing fingers. Any thoughts?

Electrically, nothing appears to happen when STAB switch is turned on. Should something happen when that is on? When BS is turned on the gyros in the norden spin up. If the two fingers in the index window touch (one of which can be manually moved with the free inner rate/displacement knob) the first A4 will release in the bomb bay. This function does work regardless of the norden being powered.

The fingers don’t move on their own, as I have scene in a youtube video of a working norden. Also the release lever moves freely up and down, but the protruding cylinder that I think is supposed to hold it in battery appears seized.

I have browsed through the BIF but have not found any answers. I am hoping you can shed some light on some of these problems.

[rwdfresno]

When I was dropping from the Beech AT-11 many years ago I used the metal sand and water filled 100 pound Mk15's as they were cheap. I could use them for about 5 to 10 drops until they were too bent up to use again. The fins would get tweaked and they never flew as straight as the first time. The drop speed in the Beech was 160 mph. When we dropped from the B-25 the higher speed (200 mph) was too much and the sheet metal bombs were not so re-usable.

Taigh,

I remember sitting in the turret of your AT-11 when Tim was being the bombardier. I remember him dropping a practice bomb on the bomb bay doors and sand pouring out and blowing around. I also remember you not being so happy about that . It was great being a 12 year old around old airplanes. Tim was sure a character but he sure was talented. I think we still have some obliterated 100 pounders around. Lately we have had regular C130 cargo drops. It is pretty cool to watch.

[Hemiman]

Nice work!!!

[Brenden S]

Videos are good. Just need the bang now

[turret nate]

Here is a video showing some of the problems I am trying to fix.

http://www.youtube.com/watch?v=WH9HEFLn ... TDJqja3nIg

[Taigh Ramey]

Taigh,

I remember sitting in the turret of your AT-11 when Tim was being the bombardier. I remember him dropping a practice bomb on the bomb bay doors and sand pouring out and blowing around. I also remember you not being so happy about that . It was great being a 12 year old around old airplanes. Tim was sure a character but he sure was talented. I think we still have some obliterated 100 pounders around. Lately we have had regular C130 cargo drops. It is pretty cool to watch.

Ryan,

Too funny. I had forgotten about Tim dropping the bomb on the AT-11 bomb bay doors. He sure was talented and a fun guy to play with. I miss him and all the fun we should have had.

Nate,

Sorry for the slow response as I have been on a trip for a while now. I saw your video and I think you have some real problems going on. I have noticed that many Norden that have been in the nose of an aircraft for any period of time, especially where the public can play with it, it is likely to be in real bad shape. The Norden is a delicate piece of equipment and will not stand up to too much public attention or exposure. We keep the running sights in a display case or in storage and use a beater for general flying. If your museum has a good sight then you might want to try a different one or its time to learn about internal Norden maintenance.

A couple of observations:

Some sights and stabilizers were sold that were restored cosmetically. Sometimes you open them up and you may find that they are not so nice inside. I have seen stabilizers with the internal wiring cut out but the wiring from the input from the stabilizer through to the bomb sight was still good. I would open up the electrical panel with the switches and connectors on the stab and see how it looks. It's just 4 screws.

As soon as you turn on the stab switch the stab gyro should power up. When the servo switch is thrown then the servo/erection motor should spin up. Since both of these do not work I would suspect that they have been disconnected as often seen on the 'restored' stabs.

A word of caution here. The gyros in the sight and the stab have large counterweights that turn at high speed and have high precision bearings. It is important that they are in good shape because if the bearings are rusted or worn out then the gyro could become unstable. A small amount of good bearing oil is often needed to keep them lubricated since they probably haven't seen any oil in many decades. The manual actually has a time needed for the gyro to spool down once power was removed. The shorter time was indicative of bad bearings. Mostly you can tell by the sound of the bearings and you hear if they sound dry or kind of grindy. From what I could hear in the video your sight head gyro sounds good but I would recommend oiling the bearings.

the outer knob on the sight head that is real stiff is the displacement knob and drives, among other things, the optics through a real fine cable. This knob should be real smooth and be sure not to force anything as you might break or stretch the cable or do other damage. The sight is real delicate and if something does not work smoothly then it can be easily hurt. Open it up and see what is going on inside. The whole rate end can be removed carefully to see what is going on. Besides the screws around the circumference you need to remove the pin that connects the rack on the trail arm.

The top casting (the one that has the caging knob) comes off of the sight easily with removing the screws too. This will give you access to the gyro and optics. You will then be able to see the fine cable that comes from the rate end through the pivot bearings and around the pulleys to drive the mirror on the optics cradle.

The caging knob simply releases the gyro. The gyro in the sight head keeps the optics cradle stabilized and level to the ground. The two silver knobs on the end cap of the sight head are for leveling the gyro. These knobs are often stuck and need help to operate properly. They can be pushed in and rotated to adjust the gyro cardan an assembly to level the gyro with the two level bubbles on top of the gyro. These knobs should spring back freely and not touch the cardan. When your gyro is spooled up then uncage the gyro and try to adjust the cardan with the leveling knobs. You can also move the sight around and see that the optics and gyro stay level. There is usually enough slop in the sight mount that you can rock it enough to see the gyro move when uncaged.

The lever you mentioned is the firing trigger for the sight and is normally held in place with the plunger. Yes the plunger should be free to ratchet into place so it will also need some attention. The fine stainless steel wire that sticks out just forward of the trigger lever and plunger can be pushed forward slightly to release the trigger. This mechanism can be accessed by removing the whole housing (4 screws). Some oil should help to free it up.

When the contacts come together in the firing circuit as the sighting angle equals the dropping angle or when the indices come together a single pulse of electricity comes out of the sight to the bombardiers panel and to the intervalometer is selected. Normally the firing mechanism is armed with the trigger lever and the sighting angle is lower than the dropping angle. As the sighting angle meets the dropping angle the contacts come together and then snap away. In the video it looks like ou are coming at it with the rate knob and holding the contacts instead if it making and breaking contact like it normally should when it operates in the opposite direction. I am not sure but this could be messing up the intervalometer. The intervalometer should just get one firing pulse and it should instantly fire off and then each successive pulse should go out in equally spaced timing. It could be that instead of one pulse the intervalometer is getting a steady 28 volts which may be messing it up. The whole having to hold down the firing button says to me that something is wrong in the intervalometer. If you have another one try swapping it out. There is an electron tube inside the the intervalometer that usually needs to warm up. From the video it almost looks like it is getting power and having to warm up to then start working. Please be sure the power circuit is wired correctly and also be sure you have the correct type of intervalometer in use for the wiring diagram. There is one with larger pins for B-29's and other aircraft that needed larger capacity circuits and I am not sure if the pin outs may have been different between the two types. Also some intervalometers were modified by the navy for firing rockets so double check to be sure the wiring in and out is correct for our circuit.

Lots of things to check.

Great work Nate

[turret nate]

Great info Taigh, thank you for taking the time to write that detailed and informative reply.

One thing that was also pointed out is that the manual calls for setting the train about 2 minutes prior to drop – apparently to let the tubes warm up in the intervalometer, so I will try the procedure again with a proper warm up in case that is the issue. Also one of our members suspects the caps in that thing will need replacement.

This unit is the 3 pin cannon plug, and wired per the diagram in the B25 manual. I have recently learned there are not only the two type of plugs as you mentioned, but also the Seeburg versus the Mallory units. The Seeburg has no tubes and more relays inside. That is the one Timothypaul1964 demonstrates on his recent youtube video.

When BS power is shut off, the unit does keep spinning for a rather long time. I would guess 3-4 minutes at least. But I will do the oiling procedure nonetheless. You very well could be right about this Norden being intended for display only, I will do some research into the history of this one. This thing probably gets handled harshly on many of our history flights. We do instruct people not to touch the bomb equipment and turrets, but as you well know that one is difficult to enforce. Perhaps we should look into budgeting for a restored Norden and follow your lead.

Is it time consuming to swap the units around? I have not attempted to remove this one from the plane yet.

The mirror on ours does seem to be stuck in the forward position, so your comment about the wire for the mirror and optic cradle could well be the problem.

I see Jay at warbird parts has a reproduction copy of “Norden Bombsight Maintenance and Calibration.” I plan to order a copy and a new production eye piece, and bombsight data book to replace the aging original in the plane.