Hardware installation should always be considered as early as possible in a design. This is exactly why I wait until it's too late. Honestly deciding way up front takes a lot of work. In fact in foam building I'd argue that actual construction takes the least amount of time. What bogs you down is the decision factor. Again CAD can help with this, but sometimes things will creep in. For this model I decided to keep things as simple as possible. A direct mount for each control surface is has got to be the easiest way of making them move by remote. One disadvantage to this method is that there will not be any leverage from any type of control horn linkage, given the size, and my ability to actually make slop free linkages, I will settle with the 1:1 ratio.
I have yet to see any detrimental performance from installing the servos right into the stabilizer, wing, or rudder. On absolute precision flying planes this type of mount induces unnecessary drag, and could also cause some unbalancing issues. Applied to small scale RC aircraft, like this P51, these effects are very difficult to even measure. There is the craftsmanship factor, but I am willing to sacrifice some scale to speed along construction. This makes for somewhat of a cheesy ground model, but in the air I challenge you to spot them. By no means however would I ever criticize one if they took a more elaborate, more scale, approach.
To mount, again I choose hot glue. It hasn't failed me yet, at least in flight. On the ground I've bonked rudders many times, breaking the bond, cleanly, so it's always easy to fix. Just remember to inspect everything before each flight. Hinge installation can easily be done as shown below.
A battery hatch was added, re-enforced by the same profile templates used earlier in the design. The idea here is that the battery, ideally, will sit at the COG so that any weight can be used. This is often difficult, so try to do the folowing:
- Mount the battery on the thrust line
- Use the weight of the battery to adjust the COG
- Be aware a diffrent battery may change the COG
The motor is mounted by making a spring sandwich. The spring is a small piece of EPP foam sandwiched between a piece of plastic and the motor. This assembly is then glued directly to the firewall. The thrust angle is then adjusted by turning the screws.
This mount works because the motor only pulls on the screws. The screws control the angle of thrust, and in the event of a sudden stop, the EPP will give possibly, and most proabably, saving the motors shaft.
Painting, the ultimate mask
I believe the biggest secrete in how I make my models is how I finish them. Seams are hidded with this special ingreadent called masking tape, sometimes even duct tape has been used to mask lines on cowles and protect underbellies. As long as the paint will stick to whatever you are putting on, feel free to use it. Now this doesn't look the best. It would never pass on a smooth sleek body, like an Extra 300, but for a tough looking war fighter, this is exactly what I want. For this plane to really shine, it needs to look used. Take a look at all the scale models out there. The seperation factor from good looking to impressive is alway in the finsih. High gloss on sports cars, rough rusty finish on tanks. Smear oil on the nose, mud up the flaps, put some boot marks on the wings. You will impress yourself.
I learned early on, silver needs a primer coat. Black works best, so a black primer was give to this Mustang. Admit it, it does look kinda neat all in black.
Next a plane-o silver was applied, actually I mixed a pearl white with a few drops of black to make silver. A large white Delta Cremacoat I bought for mixing was picked up accidently as a pearl coat. I was going to take it back when I realized it could be used for all sorts of metals.
Pretty disgusting at this point I think. In fact I was wondering if maybe I should just repaint the whole thing green as currently this silver shows all the flaws. I'm glad I didn't now, but I was worried.