The blue nosed P-51 used to be flown in formation with a friend's sport plane, later he commissioned me to build him a Mustang too, so I built the 2 yellow nosed models. We had some great formation flights with these. On a good day, we could keep them about 3 to 5 feet apart for a few circuits around the field.

The 2 yellow nosed airframes were about 95% finished when the photo was taken. Wiring for the nav lights is visible near the wing tip.
 

Fun Scale P-51 specifications:

Span:	51in.
Weight:	6 lbs. (dry)
Wing loading:	28.3 oz./sq. ft.
Engine:  Propeller:	O.S. 46sfp  2 bladed APC 11 x 7
Fuel capacity:  Flight time:	8oz.  10-15 minutes
Radio:	Futaba 7UAP
Functions:	Ailerons, elevator, rudder, throttle, landing gear, navigation lights

The original plans called for an upright engine with the cylinder head sticking out of the sleek P-51 cowling like a chimney, along with fixed gear and a simple straight taper leading edge. I modified the kit to address some aesthetic issues:

• The kit's wing was modified to include the Mustang's charactaristic double tapered leading edge. The wing structure was also modified to a stronger "D" tube structure.
• Mechanical retracts (servo driven) were added.
• Engine was inverted to preserve the clean look of the Mustang. The O.S. 46sf, performed just fine inverted. Starting the engine inverted was no problem (once in a rare while, hydralic lock would require venting the cylinder and starting the engine with the model turned upside down). With a pressure tap from the stock muffler feeding the fuel tank, priming the motor was a simple matter of blocking the muffler's exhaust opening and turning the prop over a few times.
• A fully sheeted tail assembly with a symetrical airfoil section replaced the stock kit's open frame, flat sectioned tail unit.
• The tail wheel was also moved forward to a more scale-like location.
• A home-made flasher circuit was made around the venerable 555 clock chip to drive the Mini-Mag light bulbs used in the wing tips, rudder trailing edge, and a couple of other non-scale locations.

Here's my friend's Mustang in a high-speed fly-by. Just to give you an idea, the blue nosed Mustang was clocked by a CHP's radar gun at 114 mph at the bottom of a shallow dive!

Low and slow.

Low speed flight characteristics of the Fun Scale Mustangs are very good due partly to the generouly cambered semi-symetrical airfoil, and a low wing loading. My models came out with a loading of 28 oz./sq. ft. which is higher than the design spec. of around 20 oz./sq. ft. and I wouldn't recommend going any higher with the weight. Slight up-elevator trim is needed at low speeds and when the landing gear are extended since gear extension shifts the C.G. slightly forward as well as introduces a larger drag force well below the C.G. Stalls are gentle, spins are easily entered and exited using normal techniques. Even at 28.3 oz./sq. ft., landing approaches are nice, slow, and stable, allowing 3-point landings with very short roll-outs.

High speed performance is is also very good. The APC 11x7 on the 46sfp is suited for higher speed and lower prop noise, but lower acceleration. Despite it's small size, this model can be flown quite smoothly in scale-like manuvers. With a .46, vertical performance is also good, alowing large, circular loops along with other vertical manuvers.

Engine out performance is great, again, due to the wing section and relatively low wing loading. Dead-stick energy management is a breeze. The blue nosed Mustang was eventually converted into a slope soarer by removing the engine, fuel tank and retracts, and then relocating the remaining gear to achive proper CG.

During a formation flight, my friend demolished the left wing panel of his P-51 when he failed monitor his altitude as we skimmed across a gradually rising hill. About 99% of the pieces were recovered and are shown in the box. The wing panel was rebuilt using all the recovered pieces and a few "filler" scraps.

Here's mine. The Mustang was about 200 feet out and lined up for a high speed fly-by, the idea was to level out at 3 feet, center field. Unfortunately when the model was still 100 feet out, the radio entered it's fail-safe mode locking all the control surfaces in their last position (in this case, neutral). As the plane descended towards 3 feet, I started to level out, this is when I realized that the radio had entered fail-safe mode. There was enough time to alert my friends and we all watched as she hit a dirt mound at around 80 mph, and skip back into the air, trailing dust and bits of dirt behind. Control was restored when the model skipped back into the air and I was able to make a wheels-up dead-stick landing out field. Apparently the initial impact had ripped the engine from it's aluminum mount (the mounting rails were sheared off) leaving the engine to dangle by the fuel lines. Other than the destroyed cowling and some minor dents in the under wing scoop, this was the only damage! Luckily the engine didn't fall off otherwise the balance would have been upset and the model rendered uncontrolable. The radio has since been sent back for a tune up and the plane repaired.

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last updated 07/07/2000