This post comes as a result of questions in this post regarding “elevated tail solutions/photos/tips wanted:”
In order to create enough space for a scale cockpit, we must be a wee bit creative in relocating the servos, receiver, battery, etc., from "the front area" to another place or places. As noted in several places here on RR, the pod and boom configurations need weight upfront for p[roper weight and balance, and all the electronics help in this. In scale that "forward moment" is the scale cockpit, "mini-pilots," etc. One option that readily creates more opportunities for doing this is converting to CCPM or something like it.
James (AGRAV8) has some pictures in his gallery showing how he created more room "upfront." He placed his servos on the side of the frames. But the cobra fuselage is so narrow, one is challenged enough just to enclose the main gear with the fuselage, much less stick servos out there. Based on my telephone discussions with him, I toyed with other configurations but kept coming back to this one. Thanks again James for your insights!
I cut a length of one (1) inch square stock aluminum. I then drew the outside dimensions of the Futaba 9202 servos on the new servo holder, and cut them out. I placed some plastic spacers under the servo attachment pads to insure that the servo bases do not contact the aluminum square stock. The servos are placed with the servo output shafts toward each other in the middle. The distance between the two servo output shafts then becomes the distance which is split, with one half of the distance going to one linkage making it slightly above center, and the other half of the distance going to the other linkage making it slightly below the exact center. The goal here is to insure that the two linkages are equal in length. The third CCPM servo (elevator) is mounted in the frame as originally intended. I learned from someone here on RR that a screw may be placed in the elevator swing arm linkage to stop it from swinging forward and backward. (I have searched for the post to give this person credit for his work, but I have not been able to locate his post!) I had reservations about how this would work, but when I finished it all, and began to program my radio, all those reservations went away immediately. This REALLY works well for scale! I am no sure how strong this would be for those doing Extreme 3D, but this is scale, and therefore should be more tame. An additional hole is drilled in the aluminum stock for the servo wires and connectors to come through. (I combined this with the two mounting capscrew access holes, to make one weird shaped hole that makeseverything easily accessible.) I beveled and sanded the hole so not to create a sharp edge to cut into the servo wire insulation. I think a really good idea would be to install a rubber grommet(s) here… and that is on my to-do later list.
One should use a zinc chromate primer, and then a color-coat such as a black enamel to coat the aluminum tube, both inside and out. I did not paint the exterior side that would mate with the front plate (please read the reason why below).
The aluminum tube is attached to the front plate of the frame (MA0827-10) using M3 x12mm bolts and lock nuts. For insuring frame strength, I drilled over-sized holes over the top two upper mounting capscrews in the frame and therefore did NOT use them to attach the aluminum square stock to the frame. These top bolts are accessed by drilling holes in the tube across from where you will locate them. For the bottom top two, I took advantage of these capscrews, incorporating them in this mounting. I drilled and fastened the square tube with M3x10mm bolts and lock nuts as shown in the picture. If you are still concerned (like me) that you need some more structural muscle in this attachment, add some JB Weld to the mix! I did NOT paint the side that faces the frame, and instead, rough sanded that part and also the front plate where they would touch each other. I then mixed the JB WELD and glued 'em together while tightening these two capscrews down. I do NOT ever plan on separating these two components, so I went for it! If I have to, I will order another front plate from Rick's! No inflight failures are expected! You may wish to install two more capscrews in the bottom instead of making it a permanent part of the front plate. That is obviously your call.
The throttle servo is attached to the lower radio plate, using a plastic servo housing from Tower Hobbies. The tail rotor servo is in the tailboom, also using the plastic servo housing. The Curtek lighting panel is also in the tailboom.
I used the throttle servo and the front radio plate lower support (Part MA0578-1) to sandwhich the receiver and foam jacket. The battery is attached under the tray. I cut a small 2 inch length of one (1) inch aluminum angle to make an "L" shaped tray to hold the GY401 gyro. This small tray is attached to the "front" of this front support (Part MA0578-1) with two (2) M3x10mm capscrews and locknuts. The nose turret is operated by a servo that is mounted in the nose of the fuselage.
I have also modified a NEXUS for the Kalt cobra in a similar manner. I will share this if anyone needs ideas. (Huge thanks again to Emile [CopterDoctor] for his insights on that installation.)
We now have enough room "in front and above" to create a tray that holds the scale cockpit. I apologize for how long this post is! I hope this helps!