48″ Red Eagle Happy EPP 3D Plane

I really enjoy my smaller scratch built 32″ Yak 55 as it really can’t be beat in the price vs performance category. If you haven’t built one yet just read the following link and get going!  ( Yak 55 32″ EPP Build Guide, Videos, Free plans ) Some other fantastic epp planes are made from Tech One Hobby and Skywing.

Now On To The New Plane. The 48″ Red Eagle Happy EPP plane was purchased through Hobby King (HKing) and is called EPP-3D unbreakable EPP foam model Kit on their site. It was previously available through an importer in the USA and was called Red Eagle Happy. With the introduction of HKing’s new USA warehouse they are now stocking larger size items that were previously not cost effective to ship internationally. So I made my purchase through the USA warehouse and I already had the motor and other parts to outfit the new plane.

Before the build I read the owners posts on RCgroups forum which point out some failures of the manufacture that need to be corrected and also some ideas on the build. The main modification that needed to be addressed was the tail feathers. Specifically the elevator did not have enough clearance to move freely since the horizontal stabilizer was installed to far forward. It was a fairly easy fix which necessitated new holes be drilled further back in the aluminum bracket that allows the stabilizer and elevator to be moved further back towards the tail. I also choose to mount the servos for the elevator and rudder a little differently that allowed for a better angle with the linkages. My servo placement isn’t necessary and would probably work just as well if you installed normally, plus the plane would be lighter. The build was completed and the weight of the plane came out a lot heavier than I liked but I have plenty of power with the setup.

Build Parts (after flying this is a heavy setup, would’ve built lighter)

pdf instructions

Turnigy Watt Meter results

35-48 Monster Power 950kv  / 3s 30-40c 2200mah / 12x6apc
51.80 a

35-48 Monster Power 950kv /  3s 2100 35c / 13×6.5 APC

(I’m NOT using this setup below this is strictly a bench test) :

3548 Monster Power 950kv /  4s 40-50c 2200mah turnigy /  12×6 apc
1104.5 watts

I haven’t had the chance to maiden the plane yet and the battery positioned isn’t set yet permanently but I’ll update this post with new information shortly.


Maiden went well!

Got up early in the morning and headed out while the wind was calm. Even with the plane being a lot heavier than I would’ve liked it is very floaty. I only had the chance to fly 2 batteries with about 7-8 mins on a 2200mah 3s lipo.

Hovers with ease on this setup and there isn’t a need to prop up to a 13″. I may try a 13″ prop in the future just for the heck of it and like always will add results here. The throws on the control surfaces were tremendous using the curved carbon fiber servo arms. The elevator had to be dialed down big time as well as the ailerons. The rudder was left at maximum with no exponential programmed to it either. I have 30% expo on the ailerons and elevator. I will dial back the elevator expo to allow for my own preference of faster response. The plane is a axial roll demon even with the larger aileron control throws and surface.  Knife edged a little, very easy, again very floaty. Flat spin was just as easy. Flies a lot like my EPP Yak 32″ just a little slower in doing maneuvers . I need to further work on the trimming and battery position. The pic below was nose heavy when testing inverted, power on with a slight up angle the nose was dropping pretty quick. This was surprising as my finger balance test had me thinking that I had a tail heavy plane. So the battery now in placed further back towards the leading edge of the wing.

Landing After First Flight(batt to far forward)

Upon arriving back home I cut out the zip tie landing gear support in an effort to reinforce the landing gear. The gear has a tendency to twist on landing and the wheel was toeing in. I added 2 pieces of Basswood and then drilled out the Plexiglas holes to allow for thicker zip ties. This was all put back together with a coat of White Gorilla Glue. Feels a lot more solid and should hold up to landings much better.

Landing Gear Reinforcement

While in a low knife edge I hit a fence and the fuselage was bent. I straightened it out pretty well but the carbon spars were not even. I should’ve been more careful but I cracked one of the carbon fiber spars. Wasn’t able to repair it so I then set out to find a replacement. In the meantime since the foam is EPP so I took care of the cosmetic small tears in the foam with Welder Glue which I always us for my other EPP plane. I used my digital calipers due to determine the Outside Diameter (od) of the carbon fiber spar which was 8mm. I found what I believed to be a good price and similar spar at hobby lobby and picked up a couple as well as some other parts waited for delivery. The new replacement spar is a little less thick in the inside diameter but should work.

Carbon Fiber Tube 8.0 X 7.0 x 1000 mm

Once the carbon fiber tube arrived I tested it for rigidity and felt that it was certainly enough to work as a wing spar.  I installed the spar with new metal washers and placed a good amount of thick CA glue on it and the washers and installed on plane straight while hitting it with ca accelerator. The wings are straight and level and test flights were completed and the plane is back in the lineup. The aluminum that is installed in the fuselage is a little dented from the re-bending and I can see this getting to a fatigue point rather easily if I have to do it again.



June 2011 Pics and video below


Update – Elevator Snapped, Balsa and EPP layer seperation

I wish I would’ve taken a picture of the problem but the balsa pulled away from the epp foam. In addition the foam layers also pulled away from themselves causing complete loss of the elevator while in flight. It thankfully wasn’t a hard crash but it did break the motor mount completely off, prop snapped and bent the airframe.

Fixed with white Gorilla Glue.

4 thoughts on “48″ Red Eagle Happy EPP 3D Plane

  1. Richard Parker

    Good info,

    Mine just arrived, plan to build this holiday weekend and maiden. Thank’s for the heads up for the tail wing look’s like we will be flying simialr power plant I may upgrade from the get go. Plan on 950 kv 60amp esc 13×6 prop I am going to make my own aluminum landing gear, bolt thru the aluminum stabelizer let you know how it flie’s, thank’s. grass field at our club, Buckingham rc flyer’s Florida.

  2. Jasonweb Post author

    Hope your build went well and your flying the heck out of the Red Eagle. Winds have been crazy over here in California this whole year so my Red Eagle has seen limited time in the air. Hope Florida is treating you better and allows for more flight time with your planes!

  3. Batman6583

    I just bought it the other day. It is being shipped as we speak. I can’t wait to see it. Richard, Hope your build went well. Dania Florida here, Winds have also been crazy over here jasonweb I have all the accessories now and just can’t wait for 6-16-11

    ESC Towerpro h40a
    MonsterPower 10 (1100kv) 375 watt
    Four Hobby King 15158A Digital BB/Coreless Mini Servo 25 gr.
    11.1v 2200mah 35C EZ FLITE Lipo Battery

    I plan on strengthened the wing carbon rods by epoxying smaller rods inside so they are no longer hollow.

    I also plan on strengthened the rectangular aluminum fuselage tube, by installing a carbon rod down the inside of this tube, epoxied in.

    can someone tell me what size carbon rods I will need


  4. Jasonweb Post author

    Hey Batman6583!

    The inside diameter of the carbon wing spar was smaller than the replacement I purchased (7mm). I cannot recall the exact measurement. The (2) wing spars included are hollow and very strong and shouldn’t have to be reinforced with solid carbon rods placed into them. My balsa 3d planes also have the carbon tubes for a wing spar and they experience higher loads on the wings.

    If you install a carbon rod down the aluminum, and you happen to tweak the fuselage a little bit by bending it, it will be difficult to flex it back in the other direction due to the installed carbon. Will the carbon tube prevent the fuselage from flexing at all in a crash? Not sure, but in the unlikely event you need to straighten the fuselage a little it will hinder the bend angle needed. I would just fly it as it is and if you damage the Happy to the point were the aluminum tube is crushed bend it back and at that point perhaps install the carbon.

    I hope the build goes well and also the maiden. If you decide to build with the carbon reinforcements I’d like to hear how it went and your experience with it.


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