MikeFreas

Like the title says I have a question on actuating my bomb doors. My goal is to use one servo for both. As you can see from the pictures I have moved all flight control servos out of the center of the bird to make room for a camera and other fun stuff. I have a good HiTech retract servo and several standard servos to work with. I have been racking my brain on how to get both of them working together on one servo and open wide enough to get good pictures. Any advice would be great.

MinnFlyer

My Feedback: (4)

Why the massive blocks of wood? Won't they limit your drop?

Do you want it where you can open and close the doors during flight? Or just open in flight and manually close on the ground?

rryman

My Feedback: (2)

I used flex cable on each of mine and used one servo to do them. I can send pics of it when I get home if you're interested. It works really well.
Randy

BasinBum

My Feedback: (2)

Here's my Kadet Senior that will aslo have 19 LED's, no dihedral, barn door aileron's, bolt on wing's yadda yadda yadda........

This is my first attempt at the removable bombay. I want to just put on a hatch for when it's not in use. I think I need thicker ply for the doors but so far the biggest problem is the offset of the servo. It's centered when closed but the doors won't open evenly. Perhaps a linear servo dead center is the answer, you can converst a standard servo pretty cheap. If I mounted the servo at the bottom near the doors I could use a round servo arm and set it up like retracts which is another possibility.

brownknows

I used a single retract servo at the front of the bomb bay. The servo sits so that the output shaft is runs parallel to the fuselage. I fixed a large control horn to the front edges of each door and have a steel rod extending up from these horns. The servo has a custom arm that I made that is approx 2 inches long (for my doors you need 4 inches of travel to fully open them). When the doors are closed, the servo arm points up, when it opens, it rotates 180 degrees down. The benefit of this arrangement is that when the doors are closed, there is no load on the servo motor, as the arm and servo body supports all of the weight of whatever is in the bomb bay (obviously the servo must be mounted very strongly). Here is my poor attempt at a picture of this arrangement... (looking from the rear of the bomb bay toward the front. Servo arm swings clockwise.)

BTW, do all of this at the front of the bomb bay to avoid having your cargo tangle up in the mechanism during release.

MikeFreas

I plan on shaving those down after I figure everything out. It was the only stock I had on hand to reinforce the ply. These doors are not going to hold any weight other than small things. I'm going to have some time off next week to play with it.

rryman

My Feedback: (2)

I built in the bombay on my first Senior Tele, but made an external one for the second one that I can just strap on with rubber bands, then remove it when I don't want to carry around the extra weight.
Randy

watchmego4it

My Feedback: (144)

I've had mine mounted for a while. I haven't been able to get full throw out of it but it seems to work very well. I'm now come up with sidewinders for my Sig Kadet. I've used two micro servos with a micro toggle switch. Thus breaking the ground lead on 3 volts to a #8 glow plug. The trick is to use a larger guage wire to make up for the voltage drop. AA batteries have just enough amps to push 3volt 3 foot on about a 18ga wire. So far it has worked great until I've ran out of supplies. My older flight buddies that have served overseas love it. Keeps me thinking of something new. The moderator says I can't talk about selling or shipping bottle rockets so I'll keep the opinion only.
On another note I'd like to ask an opinion. They banned the little dinky moon traveler sky rockets in some states but you can still buy a mortar cannon that's reloadable and could single handedly burn down a house or buisness. Some of them will set off your car alarm and it's way up there when it explodes. Where's the common sense in that. Smaller is worst? It's like [b]comparing a pea shooter to a 21 inch cannon. Sometimes you think lawmakers are just getting bored and looking for something new to make illegal these days....... [:-]


I still have all my fingers due to using common sense. How many do you have?? Jacob 12:24

MikeFreas

Well it took two nights in the garage to get it to work but I have operational bomb bay doors. My first design didn't end up working because the hinge point still wanted to rotate with the longer servo arm. I started over with a larger servo wheel and by adjusting the linkage attachment point I got it to work. I'm sure there is a better way to do this but I can't figure it out right now.

BasinBum

My Feedback: (2)

Is that servo arm gonna clear the wing bolt when it comes throught the blind nut? You may want to cut it down and make sure. Other than that, nice job on getting it to work.

rryman

My Feedback: (2)

Since this is a bombay door thread, here's how I did my first one. I had the same problem of figuring out how to get them to work together. This worked fairly well.
Randy

N1EDM

My Feedback: (2)

Clever idea to use those cables, Randy. All these ideas look good, but I think that the cables are definitely 'outside the box' thinking.

Bob

MikeFreas

The servo clears the wing hold down bolts just fine. I had the wing on it last night to make sure that and the camera cleared everything.

winger1955

My Feedback: (25)

Mike,

Sorry to change the subject, but do you have any additional pictures of your wing hold down method?

Thanks

MikeFreas

What part do you need pictures of? I could take some pictures tonight for you and post them here for everyone.

winger1955

My Feedback: (25)

Some close ups of the wing rib attachment area and the fuselage attachment area. Since my TM is already built, I will be retrofitting this feature.

Thanks

MikeFreas

Ok. I will get some pictures at some point tonight and post them.

MikeFreas

Here are the pictures. It's kind of hard to tell because the wing is covered. I sandwiched a piece of heavy ply cut in the shape of a wing rib between the wing halves. I cut large slots in the rib to allow the joiner pieces to slide through so there is no way it's coming apart. If you notice an also got rid of the dihedral by cutting new pieces from spruce and heavy ply. I also reinforced the forward bulkhead with heavy ply and cut a slot for the hold tap to fit. In the rear I used a piece of spruce and reinforced it with triangle pieces on the under side. All of the pieces were glued with 30 min epoxy. I don't think I will have any problems with this set up.