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Su-17 Fitter - in flight test at HOTMAC

  • 08/05/2021 5:51 PM
    Reply # 10808057 on 10784197

    Thanks for the nice comments, Steve! I hope to bring the model out tomorrow again (Friday).

    Thanks Al - and I agree - building is half of the hobby for me. I have never built a bipe before - and I eventually want to do that. Most likely a WW1 type. Looking forward to seeing yours at the field!!  

    Ron S.

  • 08/01/2021 8:41 AM
    Reply # 10787460 on 10784197

    Fabulous. I am so glad to see other member that scratch builds.

    I don't have CAD , a lathe or a 3D printer so it is interesting to see what can be done with those tools. I will post an updated photo of my Nieuport build in the hope that we can encourage more people to build their own model.

    Alan Y

  • 07/31/2021 7:52 AM
    Reply # 10785970 on 10784197

    Awesome job Ron! I was fortunate enough to watch your flights on the SU-17 recently and it was beautiful! Very well built!

  • 07/30/2021 9:22 AM
    Reply # 10784361 on 10784197

    So currently ,we are now up to flight 6, and things are slowly getting sorted out, and flights are getting better. Most recent issues I run into, is that the pilot is still learning the model... I'm adding pylons and more surface detail, and am hoping for more decent weather to get more test flights. I'd like to try more maneuvers like half cuban eights, as another test for wing strength - but given the altitude restrictions for now, I guess that'll have to wait. Last pic is the status of the model after flight 5.

    1 file
  • 07/30/2021 9:16 AM
    Reply # 10784340 on 10784197

    I had all control surfaces operating and CG had been worked out by March 2021. The model came out a bit heavier than I had hoped. By the time of first flight in April 2021, the model weighed about 49 lbs dry, with 8-9 ounces of lead in the nose. I'll still need to add pylons, stores, and much more surface detail, and a bit more cockpit detail. But the pilot was in! That was the main thing.

    So in April we did first flight on the model. The model may have been a tad tail heavy, but it was flyable. I was mostly flying slower than I should have - I did not want to learn too quickly if the wing pivot mechanism was sufficient or not. The plan was to fly the model 5-6 flights before even thinking about sweeping the wings in flight. Try to do the (hopefully) simpler and more necessary things first, then expand the envelope later.

    I landed the model, a bit fast, and it rolled into the grass at the end of the runway. I used short screws on the MLG, and managed to pull one of the main landing gear units out of the wing. Done for the day, but it flew. :-)

    2 files
  • 07/30/2021 9:05 AM
    Reply # 10784302 on 10784197

    By mid 2020, I was hoping I could get a flight on the model before the end of the year. The model had not been painted yet though. Flying in primer would have been okay, but I was still bouncing between sanding primed surfaces, doing servo installs, no canopy, no tires (at that time), and no model programming with the transmitter.

    So I decided I would start with the paint, and that would give me the time inbetween, to finish up the radio installs, and other mechanical issues (final install and adjustments of the landing gear, etc).

    I was not having best of luck with acquiring documentation on the model either. My initial plan was to model one of the Polish aircraft that was still flying, but with limited time to chase down contacts, plus language difference, I decided to settle on a Russian scheme. I won't have the best documentation, but I'll have enough to get the model flying for 2021. A "super scale" version would have to wait till later. And, if this project ends horribly, I won't have spent all the extra time in super detail, into something that does not come to fruition.

    I decided on a scheme that was flown in Templin Germany, at a Soviet operated base, where they operated 30-40 Su-17s. The entire regiment pulled out in 1994 or 1995, when most of these aircraft were flown back to Russia, where they were put in a mostly "permanent" storage. This airplane will be Yellow 27, with the sharkmouth.  :-)

    Major colors were done by December 2020.

    3 files
  • 07/30/2021 8:48 AM
    Reply # 10784271 on 10784197

    After most of the molds were finished, making parts actually started. I also worked out details on how I thought the swing wing mechanism should work. In the end, I have the outboard wings pivoting about a pair of tapered bearings. The full scale aircraft did it a bit differently, and I may have done things differently if I had known this in time. My scheme is similar to how they did it on the F-14 Tomcat, and F-111. Those were successful projects, so it should be good enough for mine!

    I'm using linear servo actuators from Servo City, to sweep the wing fwd/aft, about the tapered bearing pair. The outboard wing I have designed so it "plugs" into a large aluminum arm - and it is this arm that is swept fwd/aft by the actuator.

    Due to some tolerance issues, the outboard wing on this first prototype does not plug in as easily as hoped/planned. I've come up with a couple ideas that might remedy this on aircraft 2.

    4 files
  • 07/30/2021 8:35 AM
    Reply # 10784236 on 10784197

    The main landing gear was a difficult task on this model, for me. It's a bit complex, and is not a simple retraction - atleast relative to what I've built before. I was able to make some simplifications so I could use a commercially available retract unit, then add a strut that allows for pivoting of the strut about the retract unit as the gear comes up. Then, another strut is used to tuck the wheel closer to the strut as the landing gear comes up.

    I machined as many of the parts I could on my rather small lathe. The rest of the milled parts, I don't have a mill so I had other companies do that work for me.

    I could not find hobby tires anywhere near the size/shape I needed, so I ended up cast my own - which was always something I've wanted to try.

    5 files
  • 07/30/2021 8:24 AM
    Reply # 10784227 on 10784197

    I started this project in 2017. I started collecting as much information as I could from acquiring books, and getting anything I could find on the internet. From 3-views I was able to collect, I modeled up the airplane with cad software, so I can see where I'll eventually run into issues, and so I can get a handle on scale. I eventually settled on 1/6 scale. There are also a lot of functions on the full scale aircraft - I was going to attempt to model as many as I can as functional (the swing wing mechanism, slats, pairs of flaps, etc.)

    The basic model was intended on being all fiberglass/carbon, which means I'll need to make a master plug of everything, then make molds off of that, so I can make flyable parts.

    Enclosed pic of the plug hardware (the airplane parts in dark gray) took about a year to get to the stage shown (July 2018) The cad model I continuously update as I build, and modify.

    Molds took another year, plus a lot of epoxy resin and glass cloth. I have one pic here of the first fuselage half popped out of one of the fuselage side molds, which was late 2019. All this hardware that never gets flown, takes up a LOT of space...

    4 files
  • 07/30/2021 8:02 AM
    Message # 10784197

    Hi guys,

    Of course this is my first post. I have some time here before my eye doc appointment, so lets see if I can post something... 

    I have scratch built an Su-17M4 Fitter. It is a Soviet swing-wing attack jet that flew in the 70/80/90s, and a few more countries are still flying export versions. Here are a couple pics of the full scale airplane.

    3 files


Mailing Address:

HOTMAC

P.O. Box 8815

Waco, Texas 76714


Physical Address:

HOTMAC

3400 Over Flow Road

Waco, Texas  76712

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