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  1. #1

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    Eflite Rhapsody glow

    I'm looking at converting an Eflite Rhapsody biplane to glow using either a Saito 40 or Saito 50. The 40 is a lot lighter than the 50 so I will probably go with the 40. Has anyone converted one of these biplanes. They look fairly strong.

    The weight of the Power 25 plus battery plus ESC is 7oz + 13oz + 2oz = 22oz.
    The weight of the Saito 50 is 17oz. Servo is 0.5 oz. Tank plus nitro is 6oz (assuming 1oz fuel weighs an ounce). Receiver battery is 4oz - total of 27.5oz - 5.5oz more. More weight up front so the receiver battery would have to go way back.

    The Saito 40 is 5oz lighter which will be lighter than the electric setup especially is I use a 4oz tank.

    The other conversion that I have been considering is the Eflite P51 32e with a YS63. I have several YSs laying around. Ran one up tonight - it really pulls.

    John Gray

  2. #2

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    RE: Eflite Rhapsody glow

    I picked up the Rhapsody ARF today. The firewall looks pretty strong as does the fuselage where it connects to the firewall. The Saito will push the prop further forward than the electric motor so I will move the cowl further forward also.
    The picture shows the Saito 40 and the fuselage getting to know each other!
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    John Gray

  3. #3

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    RE: Eflite Rhapsody glow

    The shows the engine mount mounted using the existing blind nuts that would normally be used to mount the Power 25 - I realize I need to cover the firewall with ply but I am thinking of using the existing blind nuts. Currently they move in and out in a X that allows different motors (Power 25 or Power 32) to be mounted. It just so happens that the SIG engine mount that I have has holes that line up in such a way that the Saito is positioned just about right.
    The battery compartment has tons of room for a fuel tank. I am thinking of starting with a 4oz tank because I don't want too much weight forward of the CG because the Saito is 50% heavier than the intended electric.
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    John Gray

  4. #4

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    RE: Eflite Rhapsody glow

    OK - so now I could use some help. If I mount the motor inverted then the fuel line out of the tank is a good 20mm above the center of the carb - the Saito instructions say to keep the tank 5mm below - I have never paid much attention to this type of thing before because with planes design for glow the tank and carb align. I am assuming the carb being below the fuel line will cause fuel to drain from the tank when it is just sitting. Maybe I should mount the motor sideways - or perhaps run the fuel line down below the carb and then back up - kind of like the ubend in a sink. Any ideas?
    John Gray

  5. #5
    apwachholz's Avatar
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    RE: Eflite Rhapsody glow

    @jg95762
     
    Personally I've not run into issues with mounting my fuel tank above the carburetor of either my O.S. .91 4-stroke engine or my Saito .62 4-stroke. Currently in my Hangar 9 Piper Cub I'm running my Saito .62 at 90 degrees  just fine (3 or 9 o'clock depending on your vantage point) and my tank sits 10mm+ above the carb. I've been running it that way for 3 years and never had any issues. As a mater of fact, it's my best running engine save for my O.S. .25SF.

    Anyone else have any input on his question?

  6. #6

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    RE: Eflite Rhapsody glow

    Thanks. I figure the best approach is to mount the Saito and run it to see what happens. I figure if I run it, idle it, hold it upright, and inverted I should see if it has any problems. The engine fits pretty well. I will add 1/16 ply to the back and front of the firewall once I am done experimenting and know which way up, down, or sideways I am going to mount the engine. The wood of the firewall (lite ply I think) is pretty soft.
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    John Gray

  7. #7
    apwachholz's Avatar
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    RE: Eflite Rhapsody glow

    @jg95762

    Not to derail the conversation but, I've never fully understood the reasoning for holding an airplane upright or upside-down to test if the engine will run correctly (not to mention that it also seems very dangerous). Ultimately it depends if your tank is getting enough pressure to properly feed the engine; right-side-up or not. I've done all my break-in and tuning with the airplane level and not once ran into issues (I own a .91 Decathlon which is inverted all the time). Then again, that's just me….

  8. #8

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    RE: Eflite Rhapsody glow

    You may have a point but I have seen many others do it. I have had problems in the past - with 2 strokes - that wont run right when held upright. I tried it tonight and the engine ran great. Bunches of smoke and lots of power. Also it did no siphon fuel. So now I can move on to strengthening the firewall.
    John Gray

  9. #9
    apwachholz's Avatar
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    RE: Eflite Rhapsody glow

    @jg95762[/b]
    As you were talking about the engine run in / testing / etc. I was curious and posted a question on another forum about engines. You might want to check out the response if it helps out:

    http://www.rcuniverse.com/forum/m_10...m.htm#10816670

    Hope to read/see more on the progress of your bird!

  10. #10

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    RE: Eflite Rhapsody glow

    Good information - makes sense. Thanks. The people I have seen doing this are those that I race small pylon racers with - with OS25fx engines - we try to tune them to the edge to get the most out of them so holding them vertical is a way to tell if they are too lean. We race over several hours and often the temperatue changes a lot. I am supposed to race tomorrow - this gives me a bit more information to go with.

    John Gray

  11. #11

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    RE: Eflite Rhapsody glow

    These pictures show the progress so far.

    I removed the back of the existing firewall to get the nuts that were inside the firewall - they were not quite in the right spot to line up with my motor mount. I then put ply on the front and back of the firewall and used 3mm blind nuts.

    Used 3/32nd ply to a front firewall and back firewall plus two formers and two doublers and the throttle servo tray. Used 3/32nd because I had a big sheet of it!

    The intention of the formers and the doublers is to make the middle part of the plane a lot stiffer. I figure that with a heavier engine (11oz versus 7oz) and the receiver battery towards the back then there is more stress in the middle. A bad landing could cause cracks.

    Cut the 3/32nd with xacto knife to minimize the amount of sanding and to get very tight fit.

    The throttle servo is a Hitec HS65 mounted upside down - had to be careful with the placement to clear the lower wing center section which is why I used this type of connector to the servo arm. Used 15 minute epoxy on the fireway and CA elsewhere. Used thinned epoxy to fuel proof the firewall.

    Had to cut the engine mount slightly and allow the engine throttle arm go into the firewall to allow the engine to be positioned as far back as possible - it is still close to an inch further forward than the Power 25 would be. This will cause me to have to mount the cowl with spacers and to put the battery way back to get the CG in the right spot. So far so good.

    What is the trick to be able to upload multiple images - I keep getting an error.
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    John Gray

  12. #12

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    RE: Eflite Rhapsody glow

    This photo shows the 4oz Hayes tank installed. Also the blocks for mounting the cowl which mounts almost 3/4 inch forward of stock because the Saito sticks out further forward. I made the blocks from two pieces of 3/8 bass wood glued together and then drilled and tapped (the wood) for a 6-32 screw. Then used a piece of 3/4 inch triangle stock to make them stronger. You can also see the cowl which has been cut to let the Saito stick out. Cutting the cowl means you have 3 mounting tabs rather than four - so I used 5 minute epoxy mixed with micro balloons to strengthen the bond between each tab and the cowl. So far so good.
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    John Gray

  13. #13

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    RE: Eflite Rhapsody glow

    I finished the build yesterday. It took just ten days! These E-Flite ARFs are so complete with the hinges and control horns already installed and bolt on tails.
    I will post a couple of pictures soon.

    Switch:The final few modifications included adding the switch at the bottom of the fuselage just behind the wing in the what was the vent hole. I used a piece of 1/32nd ply that was slightly larger than the hole and premounted the switch to the piece of ply (after covering the ply with ultracoat) and then removed covering from aound the vent hole and used thick CA to glue the ply with the switch installed into place. I then fished the switch wires up through the cutout between the elevator servo and rudder servo.

    Battery:I thought I would have to put the battery in the fuselage behind the wing but was totally wrong. Once I got the plane together I found I had to put the battery up next to the fuel tank to get the CG at the forward end of the range in the instructions.
    I used a 5 cell AAA battery, 1000mah. The AAA are about 2 ounces lighter than the AA packs.

    Wheels:
    I used Dubro lightweight wheels to save 1.5 ounce over the stock wheels which were really heavy.

    Hatch
    I probably overengineered my modifications to the battery hatch but I had visions of it vibrating loose! I CA a piece of 3/8 bass wood behind the front former of the hatch and drilled through the firewall through the former and through the bassword with a 3/8 drill bit so that I could install two 3/8 dowels. The dowels are outside the little tabs that are already in the former. My concern with the tabs is that they are very short and might not hold if there were a lot of vibration.

    I also installed a piece of 3/8 basswood vertically inside the fuse so that I could drill through the side of the hatch and put a 6-32 nylon screw through into a threaded hole in the basswood. I did this because I thought the magnets might not hold the rear end of the hatch down. Probably unnecessary but it will give me peace of mind.

    Cowl
    I used 6-32 screws with spring washers and flat washers to install the cowl into the blocks that you can see in the last posting. My idea is that the spring washers will stop the screws from vibrating loose.

    Covering
    Because the tail section is bolted on rather than glued I was concerned that glow fuel slime would get into the joints that are left between the tail section and the fuse so I covered the joints. This makes for a cleaner look anyway.
    I may glue the wings on permanently and do the same thing to cover the gaps. It turned out that I had matching blue and white ultracoat on hand.

    I ran the Saito up and it sounds great. Had to fiddle with the throttle travel and subtrim a bunch to get a reasonable throttle curve but that was about it.

    I checked the CG again and everything looks good. Now I have to wait for a calm day to maiden. Think I will show it to the folks at the LHS first - they were curious.

    Not sure what my next project will be. If this one flys well maybe another bipe!
    John Gray

  14. #14

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    RE: Eflite Rhapsody glow

    I finally got around to flying the Rhapsody today.

    The one change I did make since my last post was to add a Perry pump. I had not used one of these before and thought it would guarantee fuel delivery given the inverted motor mount and fuel tank being considerably above the carb. The pump installs onto the back of the crankcase and need just a little trimming and dremeling to get it to mount. Seems to work well - it weighs a bit over 1 ounce so I moved the receiver battery back a little to keep the CG in the right spot.
    With the Perry pump there is no need to connect the pressure line from the tank to the muffer so I can now put on a straight pipe instead of the muffler - I have one on order - hopefully it will give it a bit more of a scale like sound.

    It flew really well. Took off in about 10 feet - a lot of lift generated by two wings I guess. It is certainly not overpowered (like most of my planes) but has enough power. It looks pretty in the air. Tracks really well. Lands extremely easily.

    Fun plane to build and to fly.


    John Gray


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