Official FMS 1500mm P-47D Razorback Thread

[davegee]

Man, that is looking great. Bob really makes the cockpit stand out. Going to be outstanding!
Best Regards, Rex

Thanks, Rex. Got the new continuous motion servo yesterday and will be experimenting with it and my printed canopy drive system to see if I can get it to work for me. As a backup, I'll be talking to the Canadian folks with their very professional linear servo that might just work for this, too. We'll see.

I don't remember if I told this story or not, but I read that when they first tried the powered canopies on the -25RE models, the windscreens were knocked clean off the airplane when they went to close the canopy! They eventually got it worked out!

Cheers

davegee

[Elbee]

davegee

Length of linear travel desired = 2.0”

Rotation of conventional servo in degrees = 120^o-160^o

Minimum radius of 360^o gear = 1.9”

Why?

Servo travel (example) = 120^o or 1/3 of 360^o

So through 120^o a round gear OD should measure 2” (6”=360^o)

For simplicity, cut a half circle or 180^o of the 6” gear in design

Circumference is p(r²) /2 where r=1.9”

Diameter = C/π = 6 / π = 6 / 3.14 = 1.90+ in

Design the rack longer by a a couple of teeth either way

Tooth size is whatever you decide, I choose 8 teeth per inch as I recall

There are gear STLs out there, I designed my own to see if I could

Yes, you could buy a linear servo with 2”+ travel, most are $70-$99 +/-

50mm travel = 2”+/- with various speeds

In any case, your canopy mounting/movement mechanism is the critical component

Best, LB

[davegee]

davegee

Length of linear travel desired = 2.0”

Rotation of conventional servo in degrees = 120^o-160^o

Minimum radius of 360^o gear = 1.9”

Why?

Servo travel (example) = 120^o or 1/3 of 360^o

So through 120^o a round gear OD should measure 2” (6”=360^o)

For simplicity, cut a half circle or 180^o of the 6” gear in design

Circumference is p(r²) /2 where r=1.9”

Diameter = C/π = 6 / π = 6 / 3.14 = 1.90+ in

Design the rack longer by a a couple of teeth either way

Tooth size is whatever you decide, I choose 8 teeth per inch as I recall

There are gear STLs out there, I designed my own to see if I could

Yes, you could buy a linear servo with 2”+ travel, most are $70-$99 +/-

50mm travel = 2”+/- with various speeds

In any case, your canopy mounting/movement mechanism is the critical component

Best, LB

Thanks, Elbee! I got a design pretty similar to yours on Thingiverse. It uses a continuous movement servo, and I just tried it with my servo tester. I think it shows promise to hook it into my receiver I'll be using on a channel that uses a rotary knob or reversible switch to get it to work. I'm still working out the required linear distance for travel open and closed, but I think the 2 inch travel estimate is accurate.

I just had a phone conversation with Actuonix out of Canada. They make professional linear servos for all sorts of uses, and some are small enough to be used on model airplanes, like canopies, for instance. I ordered one small unit to play with. It uses a moveable square metal tube that you can adjust the travel right on your radio, I guess other modelers use these too. I thought it would be worth it to give this a try, Might be workable for other model projects, too, someday. We'll see where it goes.

Thanks for your excellent piece addressing these units. I think I'll eventually find something that will work.

Cheers

davegee

[Elbee]

Precisely, I like their L12-Rs and will be using those on my F-14 project. Good choice.

[davegee]

Super! I just became aware of this company recently when researching linear servos online, which I don't know much about, but am learning. I think my biggest concern is that I have enough space in this relatively small airplane to mount the L12-R. I have the removable hatch/cockpit, and hope to mount the L12 behind the back wall where the pilot sits. I'll just have to play with it and figure a way to make it work. If done correctly, it looks like it would be a very smooth stroke pushing the canopy open and closed with the ability to set end points and rate of speed. Ian at Actuonix also told me that if the motor hits a stop, it won't get burned out or have a problem like that. When you reverse the switch, it simply returns back to where you command it.

They are working on shipping it to me now, so I'll be very happy when it shows up to go to work on it!

Cheers

davegee

[Elbee]

davegee

I had thought to change out my rack and pinion for one of these, but all is working great so if isn't broken, don't.....

Your research pays off with this company and don't forget to sign up for their you_tube channel, great information.

A little pricey, but oh so convenient and a lot of firepower in a small package.

How's shipping rates?

Best, LB

[f4u ausie]

U guys r amazing .. my mind boggles at your creativity. Awesome

[davegee]

davegee

I had thought to change out my rack and pinion for one of these, but all is working great so if isn't broken, don't.....

Your research pays off with this company and don't forget to sign up for their you_tube channel, great information.

A little pricey, but oh so convenient and a lot of firepower in a small package.

How's shipping rates?

Best, LB

I have been talking with Ian the past couple of weeks by email, and today by phone. It sounds to me like he is the head man, his son Mike does the informational videos on their products. There are complications shipping "internationally" although they are almost a stone's throw from Washington state in Canada but there is a high tariff on Canadian goods to the USA at the moment. Even so, Ian was able to negotiate the total out the door cost, including shipping via FedEx for about $90, which was fine with me. He is a big fan of RC and especially P-47s which I think piqued his interest when he found out what I wanted the servo for. We had a good laugh over things. I like the concept of their linear servos and could see them in future model projects. It seems to be very well designed and built. And the ones made for RC models are just icing on the cake!

I'll look into the you tube channel for information.

Cheers

Dave

[davegee]

Today I installed the E Flite bomb/drop tank in my oldest FMS 1.5M P-47D razorback, "I Wanted Wings." I am going to try and test the dropping of a foam drop tank from the belly location on the airplane. It works flawlessly for ground tests this afternoon, and I plan on installing similar units on my other P-47s. I already have installed and ground tested this unit in my new Hairless Joe that I am working on now. I have two other P-47s that I'll be installing the unit in soon.

I am impressed with this E Flite unit, seems to work great (on the ground.) If I fly tomorrow, or whenever I get to test it, that will be the "acid test" as to how it works. Danger Dan and I are also working on a printed STL design for a larger "flat" 150 gallon drop tank that is similar to another version they used in WWII. Once we have that design completed, I'll print it up and test fly it on these airplanes.

Below is an old tank being used as a test tank on this airplane, hopefully tomorrow. This is a OEM part that came with the FMS kit. It represents one of the 108 gallon "paper" tanks that saw extensive use during the war in Europe, especially for aircraft flying out of English bases, where these tanks were manufactured in WWII.

Update: Tried to fly this morning (Thursday), too windy crosswind. Will try again tomorrow. *sigh*

Cheers

Davegee

[davegee]

I had a successful drop tank release test on the EFlite mechanism yesterday. Dropped off just as I expected it would, began an end over end tumble and landed on the runway. I wasn't planning on that, but it is so light, that it wasn't damaged at all, not even a dent or chip.

Afterwards, I coated all the drop tanks I plan on using for the time being with Minwax PolyAcrylic with a brush. That seemed to harden them up some to avoid damage if they fall on a hard surface again, instead of the soft dirt and sage-filled surroundings.

I have now installed the E Flite mechanism on all three of my FMS P-47s and the new one, Hairless Joe, will use the drop tank release for some inflight pics later this spring or summer when it is done.

Here's a couple pics of the mechanism. For this plane, it is almost a "drop in" add-on, just had to remove the existing OEM drop tank retainers and drill a hole to feed the wire into the fuselage floor and receiver. I use the "I" button on my DX18 for easy finding without looking down at the transmitter while flying. I did have to clear out the foam just a little bit on the side to allow the spring-loaded release pin to be pulled back to attach the tanks.

Very happy with this after the first try, and will test it more next week with some other P-47s with the new mechanism. I'm hoping Danger Dan and I can jointly come up with the printed 150 gallon steel tank that was also used a bunch during this time period, especially on P-47s. it would fit using the same attachment as this foam "paper" tank, also used extensively back then.

Cheers

davegee