P-51B Mustang Shangri-La

An update as I've gotten this model fully built and flown a first flight yesterday. I built this using Hobby-Lobby's suggested ERC 300 motor, HS-55 Servos, ERC 35A ESC and for now, Power Wing 1600mah 2s batteries. I gave a poor review since the motor bolt up wasn't a "direct bolt on" as advertised, but it's easily doable, just not a direct deal for anyone who is expecting to not have to do anything but screw the screws in. The way it is you could go with three screws, but I don't trust my flying or landing that much. Four is better insurance. I glued in a piece of the provided cut-out for the fire wall.

The build went easy except the model is very fragile, so when handling it as it's being built it got a few nicks and dings. Very important to be Careful! I went with a 35A ESC since the 25A was out of stock. The set up of the model went good except for the instructions being a little vague here and there. I relied heavily on www.rcgroups.com "Alfa Appreciation Thread". Lotsa knowledge and helpful fellows there.

Flying the Mustang was fun the one chance I've had so far. With the ERC300 motor it's got plenty of power, flies in a very scale manner. Slow speed flying is possible. I put in about 1-2mm of up on both ailerons as the instructions said, but I don't think it's really needed to make smooth slow flight, or landings. With the 1600 2s I got around 12 or so minutes without the ESC cutting out. On 2s batteries it's not overpowered, so if you're looking for stupid speed, go for a bigger motor, or possibly a 3s battery. I will try one some time soon. It's nice to have the extra power to get yourself out of trouble in needed, though it can get you into trouble too.
This plane will climb a lot with more than half throttle, and like crazy with full throttle. I mixed in a bit of throttle to elevator on my DX6i and it was fine. I read that lotsa guys put a small washer to shim the motor on the top screw to help.
Over all I'm very happy the way things have turned out. The fit and finish of the Alfa birds is top notch, if a little fragile. Any issues or questions I had were quickly answered by Hobby-Lobby so thumbs up to them.
I will probably buy another Alfa from them soon.

Hobby Lobby gets a 1-star so far. I just bought this plane as it was on sale and a nostalgic looker in my eyes. I liked the "direct bolt in" statement for the ERC BL300 motor but it's not as advertised. At all. You could go with the 400 motor but in the instructions on how to mount the bigger motor they assume that the provided coupon of ply to use is bigger. On the plane they used to demonstrate it is, but not the P-51 B.
More to come as I assemble this plane...

P-51B Mustang by Alfa Models Product Review
By Delfin C. Perena (delperena@yahoo.com)

INTRODUCTION

Renowned for its WW2 (world war 2) air supremacy in the European Theater, the North American Aviation P-51 Mustangs found homes in some third world countries after the war. Through the American generosity, the Republic of the Philippines was among the recipients. With the Mustang, the (PAF) Philippine Air Force accelerated its development and re-building process.

PAF Mustangs saw post-WW2 combat actions in support of the Philippine Military ground troops against insurrections.

More significantly was the graceful display of aerobatic prowess of the PAF Blue Diamonds Aerobatic Team in the sky over Manila at air shows. While they awed the crowd, to most boys and young men, the Mustang became an icon to dream on. Very few made it to become fighter pilots. However, most maintained that dream, hoping that someday ……..

That someday is now for most of us in the fading years of our lives. Radio controlled model aircraft re-invigorates that youthful passion. It is not a dream anymore. Hobby Lobby with the Alfa Models P-51B offers realism in a very affordable way but great fun nonetheless.

THE KIT

The hollow molded foam kit consists of: A fully assembled fuselage with vertical stabilizer, horizontal stabilizer/hinged-elevator with attached pushrod and firewall/motor-mount; one-piece wing with hinged ailerons and attached pushrods with mounting space for one servo; two-piece spinner; laser-cut plywood tray for radio receiver, battery and elevator servo; a plastic-mold for a military pilot, decals, instruction manual and a graphic assembly illustration.

The major attractions are its small size (33-1/2” wingspan) and its lightweight. It is suitable for park flying and hand-launching. The Mustang’s hardened surface provides durability for landing on rough terrain. Its light weight and sleek design exude a good speed range that allows pylon-type flying as well as low-and-slow flight maneuvers.

ADDITIONAL ITEMS REQUIRED

It is very critical to define a target weight of less than the specified 16 ounces flying weight. Prudent choice of components is essential to optimize weight/performance/reliability.

Digital micro-metal-gear servos provide good response, true-centering and handle undue mechanical stresses during high-speed maneuvers and rough landings.

Motor/propeller/esc/battery were selected and tested to achieve good thrust, medium speed, low current drain with careful thermal management.

Receiver is of the 2.4 GHz type.

Initial weight estimates is less than 15 ounces.

DRY FIT

The cowling and firewall/motor mount centerlines do not match. There is an offset of 0.287”. Modification has to be made. Photographs of the before-and-after were taken.

The recommended aileron servo mount appears to be weak. A sleeve was constructed to provide lateral support and ease of removal. The aileron pushrods adjustment was transferred to the control horns from the servo arm. This is much more convenient and practical.

The latch component attached to the fuselage detached after a few in-out operations. Not surprising as it is merely glued to foam with a small contact surface.

The nose was twist-tested for possible vibration. There was a significant movement.

Paint, evident on the pushrods, required sanding and lubricant to minimize friction.

ASSEMBLY

After the corrections and modifications, assembly was relatively easy and straightforward. One puzzle is the call to install an assembled and painted pilot through a hole form underneath the cockpit. There was no pilot nor a cockpit hole. There was a plastic piece that appeared to be a mold. Out of modeling clay, a pilot was molded. However, to conserve weight, the pilot remained out of the plane.

THE MAIDEN FLIGHT

So I can take photographs, the club test pilot maidened the P-51B Mustang. Immediately, the front part of the spinner separated (captured by the camera). On landing the firewall/motor-mount/motor combo unglued from the nose. Surprisingly, other than a broken propeller, there was no other damage.

The nose is of thin foam material and the gluing contact surface is suspect. Three (3) blocks of 3/8” x 3/8” x 1-1/2” spruce with one layer of ¾” fiberglass were applied to the inside of the nose. Subsequent twist-test yielded a stiff nose section.

Right and down thrust-line offsets were also applied to correct for severe pitch-up attitude on throttle application.

SECOND MAIDEN FLIGHT

The all-up-flying weight (AUW) with 1050 mAh, 3S battery was 13.56 ounces prior to the repair and modifications. Subsequent AUW is 14.4 ounces, still below the target weight of 15 ounces.

The second maiden flight, which I did myself, was very uneventful. Trims were not required and the flight performance was very good with a broad speed range. More familiarization flights will be made before wild aerobatic maneuvers are performed.

LIKES

It is a Mustang.

Easy to hand-launch.

Small and lightweight with good flight characteristics.

In spite of corrective modifications made, it is still an easy build.

Reasonable cost.

DISLIKES

Poor firewall/motor-mount structure and fuselage attachment.

Weak aileron servo mount and control rod adjustment.

Good true-scale pictorials will help in scale decal application.

The missing pilot.

CONCLUSION

Definitely the Alfa Models P-51B Mustang is a fun plane with nostalgic touch and flavor. While relatively, an easy build, it is more suitable for the experienced intermediate pilot/modeler. Hopefully, the cowling-firewall centerline mismatch is unique to my case. Otherwise, it could frustrate the less technically inclined.

Hand-launching is easy. Just hold by the cockpit above the center-of-gravity. Apply enough throttle to feel like the plane wants to go. A mild swing with the arm, let go. With my mode-2 transmitter, my left hand is on the plane. Throttle adjustment is with my right. Subsequently, when ready for release, my right hand moves to the right stick. Please note that excessive throttle input introduces too much power and probable unwieldy torque roll.

PHOTOGRAPHS

The build and the first maiden flight were covered with high-resolution photographs.

I simply love the Alfa war birds and they now makeup a significant portion of my fleet. This Mustang from Alfa is my most recent addition. I just could not resist the sale!

While there are many Mustangs in the modeling world not too many "B" models exist - and I love them. This B model is a thing of beauty and as good as it looks, it flies even better.

With the Alfa war bird line you get both a fine looking scale ship and a plane with excellent flight performance. It flies just like it was attached to rails. The flying characteristics closely follow the other Alfa models.

Hits:
Excellent looks
Prefabrication nearly 100% -- no hinges horns or pushrods to install
Stellar flight performance
Fast assembly
Light weight
Complete hardware kit

Misses:
Canopy/battery hatch replacement can be a bit difficult

The Alfa Mustang is priced right and the recommended power system gives all the motivation you would want or need. I highly recommend it!