Martin 250 Turret

[PJ]

Is there a way to crank the turret around without power? Is there a locking pin or something that would prevent it from being hand cranked? Any pictures to illustrate this would be appreciated.
Thanks,
PJ

[Former Member]

PJ,

I'm not an expert on the Martin 250 upper turret but I do know that it has manual hand cranks. I would assume that the turret has some locking mechanism as well to keep the turret in the stowed position.

John

[Forgotten Field]

I believe the turret can be locked on the ring, but I'd have to look at it to figure it out. There are two manual cranks, one for elevation, one for azimuth. Below are photos of one of the cranks. They are connected by bicycle chain to gearing on the drive shafts of the turret. They are always in battery, but the crank handle has a small locking pin on the handle which will make it free wheel. You can just see it in the first photo, the small metal tabs at the point where the curved portion of the handle turns straight. You pull up on the little tab when the handle is in this position, and it hooks over another small tab on the large casting. I'm still training up on the turret and don't know everything about it yet- I have the manual but as I said in a few other posts, they are pretty complicated. I was really lucky to find three NOS handles, so I have one extra for anybody's project.

[Broken-Wrench]

PJ,

I'm not an expert on the Martin 250 upper turret but I do know that it has manual hand cranks. I would assume that the turret has some locking mechanism as well to keep the turret in the stowed position.

John

Speaking of turrets How did you come along getting your turret parts/ ammo cans from California?

[Former Member]

PJ,

I'm not an expert on the Martin 250 upper turret but I do know that it has manual hand cranks. I would assume that the turret has some locking mechanism as well to keep the turret in the stowed position.

John

Speaking of turrets How did you come along getting your turret parts/ ammo cans from California?

Believe it or not I was finally successful in receiving all the parts I originally paid for. I was kind of upset that it took over 2 1/2 months from the time I overnighted my payment until the time I finally received everything...but at least I received it. Judging from the numerous PM's I received it sounds as though a lot of folks have had a lot worse dealings with him over the years.

I've been shopping those ammo cans around to different people I know that would have the skills to repair and restore them. The original guy I had lined up bailed on me when he saw them and others have quoted me outragous prices of $5,000 or more to completely restore them. Some don't want the hassle and would rather tear the cans apart and use them as templates to make a brand new set. Unfortunately, that's when the costs start going through the roof. I have another guy looking at them tonight who runs a business making custom hotrod parts so we'll see if he has the courage to take this project on.

John

[Broken-Wrench]

Are they stainless or Aluminum? Stainless I would guess.

[Former Member]

Are they stainless or Aluminum? Stainless I would guess.

Correct...stainless.

John

[Dan K]

Is there a way to crank the turret around without power? Is there a locking pin or something that would prevent it from being hand cranked? Any pictures to illustrate this would be appreciated.
Thanks,
PJ

The link shows a photo of a Martin 250 I worked on many, many moons ago for the CAF in Wisconsin.

http://www.cafwi.org/caf_thumb/pv_07.jpg

If someone were seated in this photo you'd be looking at the back of his head. In the center of the casting (behind his head) you can see a small hole in the vertical lip of the casting. I'm going from memory here, but I believe there's another hole below that one on the horizontal part of the casting. That hole will line up with a hole in the lower frame (which is ultimately attached to the upper fuselage of said aircraft). A simple pin dropped into those two aligned holes is what keeps the Martin 250 from spinning around.

This turret was restored to operate as a display using the manual controls alone, and for a small donation one could sit in and operate it when displayed at local shows. The decision was made not to electrify due to the danger of having untrained fingers or other body parts hurt during operation. I also seem to recall reading from the manual that some of the electrical components--especially the amplidynes--didn't have particularly long lifespans.

[PJ]

Thanks to all. I will give a look and see if we can get the turret on the Harpoon to spin. I agree that the manual is confusing.
PJ

[Gunner]

Just make sure the seat latches are in good shape. They used to release on their own and dump you on the floor

[Dan K]

Just make sure the seat latches are in good shape. They used to release on their own and dump you on the floor

Good point. Another small mod would be to use slightly thicker wood for the seat. I recall the original being fairly warped from years of use, and your average 21st century gunner isn't getting any smaller.

[PJ]

That's correct. The seat unlatches to allow the gunner in and out, and has a strap that he uses to pull the seat uponce he is ready to sit. A cushion snaps to the wood.

[Dan K]

Just happened to see these...happy bidding.

http://cgi.ebay.com/Martin-250-turret-c ... dZViewItem

[planenutti]

Here is another Martin 250, the restorer was Col Ed Lucas, CAF. Based on the stamps on the lockout cams (not sure that is the right name) it came out of a Martin B-26. It is operational and has been to some air shows.

olddominionsquadron.org/turret.html

[Quest Master]

PJ- Here is a view of the control handles mounted on one of my M-250's:
http://www.questmasters.us/M250_Turret.html