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Old Feb 10, 2015, 08:44 PM
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Value Hobby P-51D 64.8" (1646mm) Build and Modifications Thread

Team,

The P-51D "Marie" was flown in World War 2 by Maj. Fred Ohr of Boise, Idaho. Fred Ohr was born to Korean parents in 1919 and his WW2 service extended from 1938 to 1944. After the war Maj. Ohr became a dentist and is, at the age of 95, still living in the State of Idaho.

Value Hobby in Illinois has created and is selling this 65" (64.8") model of Maj. Ohr's P-51D for $139.99. The plane is all balsa and plywood construction with a fiberglass cowling and plastic formed canopy. The plane is set up for electric components but appears to be able to handle gas or glow. The P-51 is covered and painted nicely and comes equipped with a top hatch for easy access for the placement of batteries, mechanical retracts, working flaps as well as working ailerons, rudder and elevator.

Like many ARF's out today everything is not perfect and this discussion will present the building of the plane and highlight the modifications that we found necessary for smoother operation.

The plane's owner, Mark, and I are from Wilmington, DE and fly with First State RC Club outside of the town of New Castle, DE. This is the second Value Hobby P-51D that Mark has owned. Most of the modifications that we are posting about now were made to the first plane. The first plane was a "write-off" in a crash that was, happily, not related to a failure of the airframe.

The first modification to the plane is to the wings and re-working the retract pockets for the E-Flite electric retracts. The main reason for this mod is to strengthen the rails that support the retract pivot point and to relocate the curved cutout to receive the struts spring circle. During the construction of the first plane Mark and I found that the mechanical retracts just didn't function well. Mark has had great success with these electric retracts in other planes and thought we could fit them nicely into the P-51. The mod was easy and quick on the second plane after all the thought spent on the first. Being a great success on the first plane the modification was a must.

The attached pictures of the plane are from the Value Hobby website. I will locate and post pictures of plane #1 in a later post.

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Old Feb 11, 2015, 11:40 AM
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Value Hobby P-51D Retract Pocket Modifications

Team,

Like I said in my first post the construction of the P-51D is a pretty good model right out of the box, but there a few aspects that need attention. One of these is the plane's retract pocket. We found that the, included, mechanical retracts were difficult to make function properly so we opted for the E-Flite electric retracts from Horizon Hobby instead. It would have been nice if the electric retracts were a "bolt in" swap but they weren't. The spring circle on the strut is lower towards the wheels so that meant replacing one rail to begin with. Cutting in a new arc or extending the existing one would have weakened the rail altogether. So, off the local hobby shop for a small piece of 3/8" plywood to make new rails.

The existing rails are made from 9mm plywood so the 3/8" material we can get in the USA is close enough. I made new rails 103mm long, 15mm wide and 3/8" thick. Before mounting the new rails we added plywood to support and secure the rails. I should point out that the original rails are glued to 2mm wing ribs at each end and covered with 2mm sheathing. This construction might be okay for greased landing on a blacktop runway but probably won't hold up for very long on a rough grass field.

We will let the attached pictures do the rest of the talking.

Because this post is so large I will add the picture descriptions later.

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Old Feb 11, 2015, 06:49 PM
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Value Hobby P-51D 64.8" (1646mm) Build and Modifications Thread

Team,

Mark sent me pictures of the first plane taking off and flying last summer.

Radio: Spektrum with 7000 receiver
Motor: Firepower 80 450kv from Heads Up RC
ESC: Castle Creations Talon 90
Prop: 15x10
Servos: Tower Pro Digital
Telemetry: Spektrum with Speed Probe (top speed 85mph)


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Old Feb 12, 2015, 05:12 PM
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This plane is really a joy to fly and with the retract modifications, it is a sure winner. Ralph has really made these models bullet proof with the various modifications and wood work.
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Old Feb 12, 2015, 05:16 PM
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Old Feb 13, 2015, 11:12 AM
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Value Hobby P-51D 64.8" Build and Modifications Thread

Team,

I should be very clear that my methods are just that "mine" and not necessarily the quickest or best. We are not associated with the manufacturer or seller in any way. Mark and I have looked at this model and found that, for the price, it was well worth the time and energy to make it perform better and be more serviceable. If anyone has ideas that would help a prospective buyer this would be the place for your comments and advice.

This will be a small post showing cutting in the servo cover plates. I've always felt that cutting the covering short of the opening and turning the covering into the opening was better than cutting at the opening and hoping that the covering stayed in place in flight. I am aware that this method is not practical in every situation and we didn't use it when we modified the retract pockets.

This P-51 D is equipped with two servo bays for each wing, one for the aileron and one for the flap. Although I have never flown this plane; Mark tells me it is "slippery" and does require the use of the flaps on take-off and landing.

I hope the pictures can tell the story.

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Old Feb 22, 2015, 06:25 PM
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Team,

The next step is to spray the entire plane with at dull or matt finish. Since it is cold here in Delaware now we will wait for warmer weather to pick up the build process. After the paint is dry we will begin again with the joining of the wing halves and fitting the wings to the fuse. We have found with the first plane and this one that the dowels that hold on the leading edge of the wing to the fuse don't line up with the pre-drilled holes for this purpose. The process isn't hard and just needs some attention to detail.

From there we will complete the fuse and get the P-51D in the air.

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Old May 23, 2015, 07:05 AM
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Value Hobby P-51D 64.8" Build and Modifications Thread

The dull coat paint has been applied and it looks good; the weathered effect is important for a proper appearance of warplanes. let's face it, this plane were put through a lot of stress during their service time.

Now on to the assembly of the wing. We set the CA hinges in the ailerons and flaps, installed the servos, installed the control horns, ran the servo wires, installed the electric retracts, and glued the wing panels together.

We did not show pictures of the gluing of the wing panels as it was straightforward and easy. Both wing panels are set with the proper dihedral and a strong plywood joiner is inserted into both panels prior to gluing. We strongly suggest that you dry fit the joiner into both panels and mate the panels together completely before gluing. Once you are satisfied that the wing panels will go together completely, disassemble and start the process over again using 30 minute epoxy. Make sure that the epoxy is applied to all surfaces. We have found that it is best a two man process because it is difficult to hold the wings together and wipe the excess glue that will escape the joined sections.

The rest of the wing assembly was easy and no issues were encountered.

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Old Today, 06:36 AM
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Value Hobby P-51D 64.8" Build and Modifications Thread

Team,

We are finally wrapping up the build on the P-51D by Value Hobby. After the modifications to the wing the rest of the build is pretty straight forward. We did modify the electric motor extension box but that was adding material for strength and no cutting or removal of existing wood was necessary.

This post shows the installation of the tail surfaces, the mounting the electric motor and extension and box and the tail wheel assembly.

There will be one more post showing the finished plane shortly.

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