Hangar 9 E-conversions: P-47, F4U Corsair & F6F Hellcat

Dec 07, 2011 1 Comment by

I have had the good fortune to assemble many  Hangar 9 models and have found that they have enough scale details to satisfy any pilot without compromising the performance of the airframe. They are also some of the easiest planes to do e-conversions on because the airframe is light for its size and allows for a great deal of room inside the fuselage for installing all the equipment required. 

I have included at the bottom,  step by step instructions on designing and building inexpensive motor mounts for  e-conversions as well has a great way to create battery hatches. Hope you find the information helpful. If you come up with a better idea for either I’d love to hear from you. 

First up: P 47 Thunder Bolt (The Jug)    One of my personal favorites!

   If your just getting started with WAR BIRDS this is a must have plane. Smooth flight performance, with no bad tendencies. Just the usual poor ground handling associated with most tail dagger’s. Roll outs are easy to control and the lift off is very scale. On a whim, I modified the landing gear doors and incorporated functional inner gear doors for realism. The gear doors that come with the plane are flat and the fit is not al that scale. If you don’t want to bother making new doors as I did, the simple solution for a better fit is to laminate a shaped and fitted sheet of 1/64 light plywood to the inner surface of the gear doors supplied with your model using Medium CA glue . As you glue the pieces together create a slight bow in the middle of the gear door. Hold the pieces together till dry. This will insure a flush fit between  the gear doors and the surface of the bottom of the wing once the landing gear are retracted. I don’t care much for the wheel wells supplied with most ARF’s. I chose not to install them on my model. Rather, I painted the inner wheel wells  gray instead. The advantage here is accessibility to make adjustments to the main gear and retract control rods  after a bad or rough landing. It also looks more scale than plastic wheel wells.  With the landing gear retracted you have a very smooth aerodynamic lower wing surface that creates considerably less drag.                                                                       

 

 Lets take a moment here and talk about power options for this model.

The recommended engine range for this plane is in the 60-120.  Hangar 9 says this model should weigh approximately 8 1/2  to 9 pounds ready to fly. While this  may hold true for a glow set up. Those of us that have done a few e-conversions know. A large battery like the type needed for this model can greatly affect the final weight by many ounces. I chose to use an E-fllite power 60 bl out runner motor for this e-conversion. E-flite recommends a  Castle Creations 80 amp ESC for their 60 bl out runner motor. Castle creation recommends not using the built in BEC  above 5 cell Li-Po. A separate BEC (battery eliminator circuit) was installed. This model was assembled many years earlier and availability of larger motors and higher cell count ESC’s was limited. The 60 bl  motor claims to have 1200-1400 watts of power depending on the battery cell count, discharge rates as well as the ESC’s efficiency. The 60 bl is rated between 5 and 7 cell Li-Po. Finding a ESC rated at seven cells Li-Po was a bit cost prohibitive. Not to mention the  availability of seven cell batteries is still a challenge. Six cell Li-Po batteries had become readily available so that had to suffice for the time. With the system installed I attached a Watt’s Up  meter and checked my watts out put power. I was somewhat disappointed to find I only had 950 watts thrust for this model. That amount is sufficient to fly with but doesn’t offer much more than that. My plane weighed 9 pound 10 ounces so I was a little short of the one to one power to weight ratio I’d hoped for.

FYI: For those new to electrics and who are uncertain of  how much power you need. Here’s a hint. If possible the minimum watts per pound is 100 for decent performance. E-flite’s web site is a great source for obtaining motor out put info. Just keep in mind. you should always have a margin of additional power for those emergency situations.

 See information below for power recommendations:

E-flite indicates that  50-70 watts per pound is a minimum power level for lightly loaded park flyer’s.

70-90 watts power per pound for trainers and slow flyer’s

90-110 watts per pound for sport acrobatic and so on.

My recommendation is to start at a minimum of  90 watts per pound on any plane.

Consider the air frame design attributes and the altitude you will be flying at.  These elements are  key to a successful e-conversion.

I fly at 7,000 feet. The lower density of the altitude greatly affects the performance of any aircraft regardless of the motor or engine you select. Keep this in mind:  

MORE POWER IS BETTER THAN NOT ENOUGH POWER 

With everything installed and tested, and tested and tested. Did I mention I tested everything.  A must if you care about your plane and the money invested. Also you owe it to yourself and the other pilots to make sure your plane operates safely. 

Off to the flying field for the maiden.

Everything worked beautifully and the plane took to the sky with no issues. As I expected,  power was somewhat lacking and not much additional power for those oh so awesome low fly buys. I had enough power for take offs and decent acrobatics but not much else. I just hated it when the glow guys flying the same plane lapped me time and again. 

After a few years of this I decided it was time for a change. Through some careful trading I managed to get a hold of a Castle Creations Ice 75 amp ESC. Now I could step up to a seven cell Li-Po system an hopefully get all the power my motor promised. I series a 4 cell and a 3 cell Li-Po batteries of the same mah and discharge rates together. Making sure your batteries are matched is critical by the way. With the seven cell battery power system my out put watts power rating was almost 1300  watts. Sweet, almost a 25% increase in performance. This was reflected in roll out for take offs. Shortened the distance needed to take off by half. What a difference in the air. Snap rolls are lightning fast as compared to the previous set up and almost unlimited vertical climb outs. No ones passing my plane now.

Incidentally; yes you could go to a E-flite 90 or the 110 bl out runners available but you don’t gain much after you consider the additional weight of the larger motor and heavier batter packs. These motor require higher cell counts of 8-9. Then to the expense of the higher cell count ESC comes into play.

 All in all this is a good set up for this size air frame and I don’t feel the need to change a thing.

 To further simplify things, the following to airplanes have the same power systems as the P 47 above. There I just saved you a great deal of repetitive reading.

 Hangar 9 Corsair 

The name says it all. Sort of rolls off the tongue: Coorrssaaiirr. Ya, you know what I mean.

Anyone in love with War birds will sooner or later have a Corsair. What’s not to love?

From the unique wing design, to the aggressive Stance. The Corsair is one of  Wold War II’s

truly remarkable airplanes. The original plane was powerful and agile. Just flat-out cool looking.

 Hangar 9 has done a great job with their 60 size rendering of this aircraft. 

The tracking is reasonable for a tail dragger. Lift offs are very scale, landings smooth. Just be ready to apply a little up elevator to avoid nose over on landing roll out.The flight performance is smooth and predictable. 

All in all the Hangar 9 Corsair 60 is a joy to fly. 

A few modifications have been done to this Corsair. Mostly centered around the e-conversion. I should mention, all my airplanes have an access hatch for ease of battery installation, removal and adjustments. This plane is no exception.

The hatch was installed on the top of the fuselage just in front of the canopy.  This was the best location available with the least amount of impact on the structural integrity of the fuse. The hatch was cut using the method descibed below so I won’t waste time on an explanation of the process here. Notice I added the white lines. This was done to lessen the visual impact of the hatch on the overall appearance of the plane. 

 The hatch allows more that ample  room to install and retreave the battery packs.  I used two batteries, a 3 cell and a 4 cell 4000 mah 30 C Li-Po’s fpurchased from  Hobby King. The batteries are series together to create the 7 cell system. This set up provides more then enough power. Roll-outs are very short and thepower system supplies all the torque you could want. 

Of course you could opt for more power and install a  90 bl  or 110 lb out runner  motor in  this model as well.  The trade-off as always is  greater weight which translates to  higher wing loading.Also faster landing and take off speeds may be required to maintain stability of the aircraft. Then to the added expense of the ESC required for higher cell counts combined with the cost of  larger cell count batteries could be a major deterrent. 

Consider carefully. 

 The Corsair fly’s very scale with this set up at 7,000 feet here in Colorado Springs. It should be awesome at lower elevations.  

LIGHTER IS ALWAYS BETTER 

Hangar 9 has done a great job with this airplane and anyone with a little under wing experience should have few problems. One thing should be mentioned: On early versions of this plane. Hangar 9 indicated in the build manual;  the proper C of G is located at 5-in behind the leading edge of the wing. As notated on page 49 of the assembly manual. I strongly encourage you to balance the model  between 4- 4 1/2-in behind the leading edge. Preferably 4-in for your maiden. Better nose heavy than tail heavy. At 5-in your plane will be tail heavy and very difficult to control, if controllable at all.. If you want to check the proper C of G for this airplane using an independant source there are countless C of G calculators available on-line. Try the site below and if you like it save to you favorites. It’s very accurate and takes in more detail than some other C of G calculators out there.

http://www.geistware.com/rcmodeling/cg_super_calc.htm 

 One final note: If you choose to use a C of G calculator: when measuring the outer wing cord, ignore the contoured portion of the wing tip and use the longest straight line that can be measured.

 Hangar 9 Hellcat

 

 What a great plane. Awesome looks and really fun to fly. This model brings all the best that I have come to expect from Hangar 9 model planes. Lots of room inside the fuselage for any electric and/or pneumatic components. If modifications are needed as in the case of an e-conversion. The volume inside the fuse makes this easy. 

Roll outs are straight with solid ground handling. Take offs are very stable with no bad tendencies. When it’s time for a landing. This plane is very smooth, all be it a little faster than some of the other Warbirds in this 60 size segment. I wouldn’t recommend this plane untill you have a good deal of under wing experience. The wing loading is a little high and this requires more experience on the part of the pilot. As with most Warbirds, a nose over tendency exists. Be ready to apply a little up elevator after touch downs. Keep applying the elevator until the plane is at a complete stop. You should have no problems.

 As with the Corsair above. The only modification made was the installation of a battery hatch and battery retainer tray. Eventually I’ll get around to main landing gear and inner gear doors. But for now I just enjoy flying this model.

 When doing e-conversions, it’s often best to assume the high voltage battery(s) and flight battery need to be as far forward as possible. Allow for  larger battery configuration when designing the modification to your model. You can always reduce the size of the battery tray using fill material if the battery is loose. Notice in the photo above.  The battery tray is located forward and a downward angle. This allows for easy installation and removal of your battery(s). Further, it reduces the need for a larger opening. By placing the battery tray at an angle. The battery is less likely to shift backward during flight. There are no straps used to secure the battery. The tray is a snug fit and a piece of gray foam is used to creat friction and tension. 

On this model the hatch was cut out and reused, unlike the two models above. On the Jug and the Corsair, new hatches were fabricated. I guess I must be getting better at this.

 

The following are instructions for modifications mentioned above.

This information was provided in a previous blog and forwarded her for the convenience of the reader. Not all references and descriptions directly relate to the planes featured above.

 Hatch Modifications

                                                                            Step One: 

Invert the fuse on you work table. Put a small t-pin from the inside of the fuse through the balsa sheeting next to the ply former. Place two additional t-pins approximately 2″ from the center pin to both sides. Do this for the front and rear formers. Turn the fuse right side up.Use the protruding ends of the pins as a guide and run a piece of  low tack tape between the pins. Make sure the tape is in the inside of the pins relative to the hatch opening to be cut. Do this for front and rear formers. Your mustang comes with black covering on the top of the fuse. Use the black covering as a guide for the side cuts. Using tape along these cuts can help keep you hand steady and your cut straight. Remove all the pins and you will have a pattern to cut out your hatch.

                                                                           Step Two: 

Be careful and go slow. Don’t be overly concerned about saving the cut out piece this time. more than likely you’ll need to sand the opening after you make you cuts. If you can reuse the cut out section that’s great. Remember there is a stringer that will need to be cut through at the center, so again go slow and take your time. If all went well you should have a nice opening in the top of your new model. The opening may have slight over hangs of  the formers. That means you did it right. Take a razor blade and put a cut at each corner of the opening. Pull back the covering slightly and sand your opening. Fold the covering over the edge and iron back in place. If you made a perfect cut or are satisfied with the opening and were able to save the piece you removed. the above step is not necessary.

                                                                          Step Three: 

You are now going to create end formers for your hatch. Size two end formers out of 3/32 balsa so that the fit flush with the fuse formers inside your new opening, Make sure the grain is horizontal and that the end formers rise above and drop below the opening so you can sand to shape later. One at a time hold the end formers in place and trace the shape of the respective formers onto the end former material. Mark each former front and rear as well as inside and outside to keep them referenced correctly. Mark the center of each end former and verify the fit. Each end former should fit and line up with the shape of the fuse formers. Make sure that the formers are below the sheeting used on the model such that when the hatch is sheeted it will be flush with the surrounding surface. Cut a notch in the center of each former to allow a 1/4 by 1/4 balsa stringer to be installed between the end formers. Place clear kitchen wrap at each end of the hatch opening so no glue will contact the surface of your model. Pin the end formers in their respective positions and fit the 1/4 by 1/4 balsa center stringer in place. If satisfied with the fit, glue the stringer to the end caps.

Cut two side stringer from  1/4 by 1/4 stock. These stringers will cut to fit t up against each end former at the bottom corners. Insure the fit is snug then glue in place. For those using new material, remove the hatch structure to verify it isn’t glued or bound in place. From 3/32 stock cut a section of material slightly lager than the hatch structure to allow for sanding and adjustments. The grain should be directed fore  and aft to allow for ease of bending. Place your hatch structure on you build surface and note whether it sits flat on the surface. If it is not flat do not make adjustments. This is the shape of you opening and the hatch is a custom fit so live with it. Instead shim were needed so you can apply light pressure without distorting the shape. Take your previously cut 3/32 sheeting and spray both sides with Windex or some other Alcohol based cleaner. This will allow the material to bend more easily. Once satisfied that the material is a good fit glue the 3/32 balsa to you structure

  Note: If you are using the cut out section do not install it yet. Remove the covering and discard.  Wait till you have your side stringer installed then text fit before gluing. Remove the structure to insure it is not glued in place and that it is not binding, then reinsert in the opening. Make any adjustment to the strings ie. sanding etc… then glue you cover in place. 

                                                                          Step Four: 

Some sanding will need to be done for a tight smooth fit. Test fit often while sanding. Finish sand with 220 grit. Before applying the covering you need to decide how the hatch will be secured in place. Decision time. Will you use hinges to attach your new hatch or would you prefer magnets. It’s up to you. If you choose magnets, some addition material will need to be added to the inside of the hatch for placement of the magnets. Should you select the hinge method I recommend plastic style that can be purchased at your local hobby store. Use Epoxy to secure the hinges in place. One other option exists. You may choose to install a dowel in the front of you hatch and a locking pin in the rear. However some additional adjustments will be required to prevent binding during removal and installation of the hatch. At this point I would recommend one of the aforementioned methods.

By the way, use Rare Earth magnets also available at the local hobby store. They are stronger and smaller than conventional magnet available at the local hardware store. Apply your  covering of choice prior to hinging and at any time if using magnets. That’s it, you now have a custom access hatch to make battery installation and removal possible. Fly, charge and fly again with no fuss. This drive the glow guys nuts. You just plug and play. You never have to disassemble your model other than possibly for transport. 

                                                                          Step Five: 

Make sure your battery will fit through the opening and will slide forward all the way to the firewall. If you purchased the battery and tested fitted after cutting hatch opening, there should be no problem. Place a thick piece of foam inside and in front of the battery location to insure no damage from rough surfaces  will come in contact with your battery. Create a battery tray from scrap and glue the tray inside the fuse. Make sure the battery tray will allow the battery to slide far enough down for the hatch cover to be installed flush with the fuse. If you like, epoxy Velcro straps to secure your battery after determining the proper battery location in the fuse. If this is done correctly, the battery can be moved forward or backward to obtain proper C o G.

Just so you know; when I did this modification for the fist time it  took about three to four hours. The next time you do this it won’t take you the three to four hours you just spent.  I can  do this type of modification in about an hour, so hang in there. You can too. 

Installing your motor and ESC: 

                                                                           Step One:

 

The best way to start is by placing the cowl on the fuse in the approximate location where it will later be permanently installed. Don’t fuss too much. You will have the ability to make adjustments later. Slide the cowl on the fuse. Place a piece of tape slightly under the cowl on the fuse at the top, bottom and both sides. Mark where the edge of the cowl overlaps the fuse on each piece of tape with a pen or sharp marker. These are your reference points for test fitting after the motor and mount are installed. With the cowl still in place and at your reference points, measure the distance from the firewall to the forward most end of the cowl. This should be approximately 4 1/8 to 4 1/4 inches. Remove the cowl and set it aside.

                                                                           Step Two: 

Install the mounting hardware on your E-flite 46 BL out runner motor. Install the prop adapter on the shaft with the collar on. Place the motor on a flat surface with the mount flush with the surface. You will have to let the shaft overhangs the edge of the flat surface for this procedure. Measure the distance from the flat surface to the forward most location of the prop adapter collar.One you have the measurement. you need to subtract it from the overall measurement of the firewall to the front of the cowl. This will provide the total length of your motor mount. Example Total measurement from the fire wall to the cowl : 4 1/4 minus the length of the motor with adapter 2 1/8 = 2 1/8 long motor mount. Your numbers may very but you get the point. Note: Before building the mount trace the fire wall shape on a scrap piece of paper so you have a reference as to the maximum size of your motor mount one attached to the firewall. Remember the mount must fit inside the cowl and be offset  to allow the motor position to line up in center in the forward opening of the cowl.

                                                                            Step Three: 

There are a few options as to what type of mount may be used. Metal motor mounts are available from several manufactures. In this section I will assume you’re making your own mount. From a sheet of 1/4 inch lite plywood cut two side pieces per your length measurement (approx. 2 1/4″ long and 2 1/4″ high) These are your right and left side pieces. From the same plywood sheet cut two pieces at the length of your measurement (approx.2 1/4″ by 2 3/4″). These are the top and bottom of your motor mount.

 

 

                                                                         Step Four: 

Place all four pieces on edge on your flat surface so that they stand 2 1/4 ” high. Over lap the side pieces with the top and bottom pieces.. If all pieces are roughly the same height then mix some 5 minute epoxy for gluing the pieces together. Note: they don’t have to be perfect at this point, just as long as the matting surfaces are flush between the top and sides and the mount is reasonably square. Apply  epoxy to the matting surfaces and clamp in place. Try to keep it square After the epoxy is set sand the front and back of the mount surfaces flush. Next you need to make the front and rear mounting surfaces. Place you mount on the lite plywood sheet used previously and trace the mount shape on the inside of you mount frame. Mark as front. Do the same for the rear piece. When cutting out both the front and rear pieces stay outside the lines. It’s easier to do a little sanding for a snug fit. If you cut on the line or inside the line you piece will be loose or not usable. Once satisfied with the fit of the front and rear mounting plates move on to the next step.

                                                                            Step Five: 

Place each mounting plate on you build surface. Draw a diagonal line from each corner creating an X pattern on the surface of the plate. Drill a 3/4″ hole in the center of the front plate to allow the shaft of the motor to fit through. Center the motor on the place and mark where the mount hole are. Drill the mount hole over-size so your blind nuts collars will fit snug. Install blind nuts in the holes and tighten the motor in place to set the blind nuts. Carefully remove the mounter without disturbing the blind nuts. Apply a small amount of epoxy to each blind nut careful not to get any epoxy on the nuts.

Place the rear mount plate on your build surface. Drill 4 holes on the X line approximately 1/4″ from the corners. Make these holes so you can push the screws to be used through to holes but not to loose. I recommend size 8 by 1/2 metal screws for this application. You may wish to trim the screws after you have done an initial attachment to the fuse to avoid the screws coming in contact with the battery.

Epoxy front mounting plate in your mount. Do not epoxy the rear plate at this time. Place the rear plate inside you mount temporarily.

                                                                            Step Six: 

Most models come with the right thrust angle built-in but you will need to create a down thrust angle between the mount and the motor. Mount the motor to the motor mount wires facing down.Placing two small washers as a spacer between the back of the  mount supplied with the motor and the motor mount you just created at the top two screw locations. You now have a down thrust angle to start from. Some adjustments may be needed after initial flight. This must be done before you align the motor and cowl to insure proper center position of the motor relative to the cowl opening. Stand the fuselage on its tail with the firewall facing up toward you and stabilize the fuse in place.Place the motor mount with motor still attached on the firewall. Slide the cowl over the motor and align on the tape marks on the fuselage you made previously. Verify that the motor protrudes the desired amount for prop  and spinner clearance if a spinner is to be used. The best way to get a great alignment is to place the spinner back plate on the prop adapter  with the cowl in place. Make adjustments to the motor position using the spinner plate as a guide. When satisfied, carefully remove the spinner plate and the cowl. Do not disturb the motor. With the cowl off trace around the motor mount  marking it’s position on the firewall. Using a 90 degree pick tool mark the mounting  holes on the firewall by placing the pick tool through each pre-drilled mounting hole.

                                                                          Step Seven: 

Lift the mount from the firewall and remove the back plate of the mount. Verify the marks on the firewall line up with the holes in the back plate. Drill undersized holes at each of the marks. Mount your back plate to the firewall with the # 8 screws recommended and trimmed to the proper length. Slide the mount over the back plate, reinstall cowl and spinner back plate to verify proper alignment. If satisfied remove cowl and spinner plate and attach the mount. At this pint you may with to permanently install the mount or may elect to make the mount removable.  To permanently install simply epoxy the mount to the backing plate. To make your mount removable simply drill holes through the sides and into the back mount plate  with the mount resting on your build bench prior to mounting the backing plate to the firewall. Mount the back plate to the firewall then attach the rest of the mount to the back plate with screws  through the holes you just drilled.

You may choose to add gussets’ to this structure to increase strength, but it’s really not necessary if you used good plywood. You can also epoxy the back mounting plate in place, but again not necessary.

                                                                              Step Eight: 

Mounting the ESC is very easy. Drill a 3/4″ hole in the firewall just below the motor mount to allow the wiring to pass through. This creates ventilation for cooling the ESC and battery. Locate the ESC on any flat surface  and attach using Velcro. Make sure the Deans plug  end of the ECS is easy to reach through the hatch opening.  Insure the wire to the receiver will reach.  Make a hole in the bottom of the fuse to improve ventilation if you so desire.

                              Have fun and let me know if this helped.

 

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About the author

Romi Lucas has been building and flying model airplanes since 1971. Electric conversions are his specialty. He enjoys designing, building and flying unique and rare model aircraft. When he isn't building or flying, Romi meets with junior ROTC officers and students at local high schools to promote youth involvement with the hobby.

One Response to “Hangar 9 E-conversions: P-47, F4U Corsair & F6F Hellcat”

  1. Pat says:

    Great article ..Thanks..& TRIPPLE thanks for the link “C of G calculators ” A VERY nice tool..and i tested it..came out Spot on. Just wanted to say Thank you!

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