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Official Freewing 90mm F-15C Eagle Thread

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  • Here are some pics for the LED and whistle mod. I'm a little concerned with air restriction negatively affecting thrust. I tried to smooth everything out with some foam filler. Does anyone happen to know any thrust values for the high performance version? I have a digital fish scale I could use to determine force, but without having done it beforehand, I don't have anything to compare it to. I talked to Wayne at MRC and he said I should be fine. What do you all think?

    Finishing touches on this bird will involve some weathering with the airbrush. I'll get more pics up when it's finished!









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    • I usually drill holes in the foam deep enough to seat the whistles all the way to their shoulder. How did you secure yours?

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      • Smooth is important ,especially coming out of the fan.

        I'd consider:
        Get stiff paper and make a fairing from back of the fan housing to the ID of the LEDs, harden the paper with thin CA Then thin stiff clear plastic from ID of the LED ring back to meet the foam efflux tube far back as you reasonably can, with holes for the whistles to stick in.

        I also suspect that plane violates the 80% to 85% FSA at the tailpipes rule.
        FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

        current planes from 1/2 oz to 22 lbs

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        • Originally posted by RCjetdude View Post
          I usually drill holes in the foam deep enough to seat the whistles all the way to their shoulder. How did you secure yours?
          I tested them at different heights. Started out seating them completely, but found the sound wasn't what I had wanted. Incrementally moved them up until I got the desired sound. I just used foam filler to secure, and attempted my best effort to keep the lines smooth. Hope this works.

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          • Originally posted by fhhuber View Post
            Smooth is important ,especially coming out of the fan.

            I'd consider:
            Get stiff paper and make a fairing from back of the fan housing to the ID of the LEDs, harden the paper with thin CA Then thin stiff clear plastic from ID of the LED ring back to meet the foam efflux tube far back as you reasonably can, with holes for the whistles to stick in.

            I also suspect that plane violates the 80% to 85% FSA at the tailpipes rule.
            I feel like I've complicated matters with this setup. I didn't realize they make smaller twin LED rings. Maybe I should've just looked into this. I could remove the exhaust nozzles and cut to fit and this would avoid any airflow complications. I'm a little paranoid to get this up now, even with the fairing modifications. Do I go back to the drawing board?

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            • Anyone with a stock setup willing to participate in a little experiment, preferably the high performance version? I have a digital fish scale I could film a few pulls and register the thrust in lbs. I could ship a small thumb drive with the files so you can attempt to replicate the same pulls and record with your phone and load back to the thumb drive. I'll pay for shipping both ways. Maybe a Starbucks card for your troubles?

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              • The difference will be in power needed for any given level flight steady airspeed with the higher speeds being affected more by the turbulated eflux (and by deviation from the desired total exit area)

                Some excess exit area is potentially good for takeoff, bad for top speed.
                Drag due to the ducting not being smooth is just that... drag. It slows the airflow making you need more power to move the same amount of air.

                So, even if its "really bad" It should still fly, just not as fast. and with lower duration when you aren't running WOT all the time because you need higher throttle for any given airspeed.

                The ring restriction isn't excessive for the fan. Its a bit close to the fan but with smoothing the flow shouldn't be much of an issue. Maybe a couple MPH top speed loss if you smooth the flow.

                A fish scale pull test vs one without the ring and whistles might not show much (using the same fan) because both will hit the fan stall due to excess rpm for available air intake.
                FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

                current planes from 1/2 oz to 22 lbs

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                • Thanks for the insight. The more I read and hear about, the more and more I realize there's just so much more to learn. I'm willing to sacrifice top end as I don't consider myself addicted to speed. I suppose once it's in the air and I notice significant instability, I will need to strip it down and get back to stock. Otherwise, if I can modify the surfaces to compensate, I'm okay with sacrificing a little speed despite paying for more of it. :Whew:

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                  • I have 2 admiral 40c 5000 4 cells that fit on the battery tray nicely with plenty of room to shift for cog. But first, I need to shorten the ail, elev, and rudder wires that go to the gyro, so that I don't have a lot of wire clutter in the aft section of the battery compartment. I'm anal about this with all my jets. The plane as received is a rats nest of wires. I want neat, organized cable ways.

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                    • I am the same way.

                      Before....

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                      After....

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                      Ahhh. All better.

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                      • yeah, I just went through my stinger 90. It was a rats nest too. So I procrastinated on this one a little, but I'm on it now.

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                        • I just did the radio install on an FMS 90mm Super Scorpion. It has a connector board with wires coming forward off the bottom of it located aft of the battery tray. The leads on the board are only about 4-5" long so to add a receiver would mean having to locate it behind the battery. I wanted to install an Admiral 6ch stabilization receiver and needed a horizontal, easily accessible location for it. The plane also does not have a removable battery tray which I have become spoiled on thanks to Freewings recent releases so I made my own removable tray and extended the leads from the board. This also allowed the leads coming off the bottom of the connector board to naturally run forward under the tray. The end result is a super clean radio installation.

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                          • Finally finished the afterburn light install. Just what I need, six more wires and controller inside this thing. Time for wire organization. Here goes another week.:Whew:

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                            • Great install. Is this the dual 64mm? I wish I would've done this over the single 90. We'll see how it flies, but maybe I'll configure it this way if the flight characteristics are affected. I imagine this will be far more esthetic. Might I suggest the aluminum tape trick to allow for greater effect through reflection?

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                              • Yes, which size rings did you order Phatbob ? BTW, great job !

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                                • Originally posted by purduephigam View Post
                                  Great install. Is this the dual 64mm? I wish I would've done this over the single 90. We'll see how it flies, but maybe I'll configure it this way if the flight characteristics are affected. I imagine this will be far more esthetic. Might I suggest the aluminum tape trick to allow for greater effect through reflection?
                                  Yes, the 64mm. I added ply hard points to make my nozzles removable. I will line the nozzles with chrome bare-metal. I did it with two of my f-16's.

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                                  • I'm not worthy! That's badass.... :Drooling:

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                                    • Finally got my wires organized. It took me my entire Saturday. I have the AB controller and BEC mounted under the airbrake. I'll install the cover under the brake tomorrow. Now to program my radio and balance her, then wait for spring.

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                                      • How are you guys setting up your radio mix for flap/airbrake?

                                        I'm using a DX9 set up with flap/aileron wing. I'm on a 3-position switch with the brake y-harnessed off the flaps.

                                        I see that the brake operates at position 1&3 of the switch but flap is at full 90 degrees at position 3.
                                        When I attempt flap servo position adjustment at switch position 3, I loose brake function. That tells me the brake servo is on/off only.

                                        Do some of you fly this way, or do I run brake on a separate channel mixed with flaps?

                                        I apologize if this was covered prior to me asking. I couldn't find my answer here.

                                        Thanks!!

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                                        • I have put my air brake on a separate channel and 2-position switch. That way I can try with and without it. Some use it some don't. Those that use it have it tied in with flaps and some separate it. I have heard it is quite effective. For me I tried to keep it simple although it is an extra switch. If I like how it feels with the brake open then I can always try to get it to work with the flaps later.

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