SU-27 Build Guidance and Pictures

[Flitedesign 3d]

This is the build assistance thread for the SU-27. If you want to give this jet a try this is the place you can share your journey and ask for help.

Plans for the SU-27 here: https://forum.flitetest.com/index.php?resources/sukhoi-su-27.239/

Development thread: https://forum.flitetest.com/index.php?threads/twin-edf-su-27.67480/

 

[Flitedesign 3d]

Second batch of pictures due to the limit of 100 files

 

[christ98406]

thank you

 

[Oldrover TJ]

2 counter rotating 4s EDFs on order!

 

[xinyue722]

Thank you. I really appreciate your generosity.

 

[Oldrover TJ]

OK So I'm kinda stuck on the 3D printing stuff. I thought I had a guy who was able to print the parts for me but his printer melted so that was a bust.

I'm considering just buying a printer and being done with it.

 

[Oldrover TJ]

Look what showed up today!

 

[The Hangar]

Alright, I’m looking at what parts to order. Currently I have two 70mm 6 blade fans, but they aren’t very powerful and I’m worried they wouldn’t be able to fly the su-27. I’m looking into getting another pair, and I can either get 4s edf’s (1500g of thrust each) or 6s fans (2200g of thrust each.) I’m leaning towards the 6s fans since they have considerably more thrust and I have several 5000 6s packs that I could use. The only potential problem would be weight, but I’m guessing it would be fine. Any thoughts?

 

[Oldrover TJ]

I've been told a 6s setup might be too heavy for the airframe without significant carbon reinforcement. Based upon the build so far, it seems the brilliance of this design is the low wing loading and light construction, at least for an EDF. I think a 6s battery would at minimum require wing spars and a reinforce nose to handle the battery weight. The 3d printed parts also might need to be beefed up. They seem rather unsupported to handle 6s thrust and speed.

I think it was only 80 bucks for the freewing Fans. I didn't have any spare ESCs laying around so that added to the cost.

For me the issue is learning about 3D printing and getting a part that isn't just a pile of scrap.

This is my new favorite plane. It my even top my old eflite beast!

 

[The Hangar]

I've been told a 6s setup might be too heavy for the airframe without significant carbon reinforcement. Based upon the build so far, it seems the brilliance of this design is the low wing loading and light construction, at least for an EDF. I think a 6s battery would at minimum require wing spars and a reinforce nose to handle the battery weight. The 3d printed parts also might need to be beefed up. They seem rather unsupported to handle 6s thrust and speed.

I think it was only 80 bucks for the freewing Fans. I didn't have any spare ESCs laying around so that added to the cost.

For me the issue is learning about 3D printing and getting a part that isn't just a pile of scrap.

This is my new favorite plane. It my even top my old eflite beast!

If it can top the beast that’s impressive! I may give it a go with the 4s fans I currently have then. My guess is that they put out about 1200 grams of thrust each. I used one in my x-29 and it worked, but there wasn’t a lot of extra power to spare. If it’s underpowered, I can always build another, right?

 

[cyclone3350]

This is the build assistance thread for the SU-27. If you want to give this jet a try this is the place you can share your journey and ask for help.

Plans for the SU-27 here: https://forum.flitetest.com/index.php?resources/sukhoi-su-27.239/

Development thread: https://forum.flitetest.com/index.php?threads/twin-edf-su-27.67480/

I am not sure which impressed the most. The way the final project came out or the way it was designed and how it went together. Saw the video. I have a pair 1950kv FMS 6s 70"s for my F-5 project and I hope they sound like this one.

 

[Oldrover TJ]

I really miss 3D flying but I just don't have the time to practice. It's been almost a decade since I was really able to thrash her.

The X29 is a heavy plane. It's got terrible airflow to the EDF and a ton of drag for what it is. Compared to the L39 I was amazed at how fast a 4s setup could be.

At least it's an enjoyable build! Nothing is particularly difficult to shape or cut out other than the main fuse plate.

 

[jfaleo1]

I've been told a 6s setup might be too heavy for the airframe without significant carbon reinforcement. Based upon the build so far, it seems the brilliance of this design is the low wing loading and light construction, at least for an EDF.

Yup reinforced spars The weight of that 6S battery does not go well with the foam spars even with an added wood dowel. I am short a 6s battery, 80A ESC and my L-39 because I did not us aluminum or carbon fiber in the spars. This design does however lend itself to being beefed up as I have been seeing it.

 

[Flitedesign 3d]

The weight or wing loading alone is not the issue, it depends on what you are trying to build. These jets fly with significantly higher wing loading too but it makes them difficult to land and almost impossible to hand launch so you need landing gear. Most of the commercial edf jets have a very high wing loading and they run on a higher voltage and they have landing gear. As for the shape and size the SU-27 is really close to Ben's F-18 and it flew at about 4000g if I remember correctly.

The reason why I prefer 4s over 6s is because its just simpler, lighter and cheaper. Sure the construction should be a bit more rigid on 6s but after all the wings need to be only as rigid as how aggressively you want to fly... Overbuilding is also a common mistake that I have experienced too many times. Also even if a 6s fan has a higher static thrust, it is not equal to the thrust of the jet. Mass flow rate or thrust in this case is proportional to the airspeed in the duct, but the power required increases dramatically as the airspeed increases. This is why you might want to consider cheat inlets if you go with 6s, to make use of the power. I have not any experience in what I just said, just what I'm thinking.

@The Hangar I think the 4s fans will get the plane in the air but probably won't perform as good. If you go with 6s and 5Ah battery it will probably end up about 500g heavier as mine which is not that dramatic if you are comfortable hand launching it.

@Oldrover TJ Have you started the build? If so please share it here, I'm curious to see

 

[Oldrover TJ]

I will when I have good pictures to show. Right now it's been a lot of plans cutting and figuring out how to use a 3d printer. But I did get some more foam

 

[Oldrover TJ]

Ok so update time! I have the plans made and cut out.


I did some laying out with the plans so I knew more or less what needed to go where and that I wasn't missing any thing.

I glued those pieces after the bottom plate. It was a little unclear which way they were supposed to go. I'm really bad at the whole A/B fold thing. That main plate was a lot to cut out though.

I had to think about this bit, former F4 needs to be in place before F3C.

So far so good I think. Still a lot of work ahead. My build isn't nearly so clean but that's probably error due to cutting plans and parts by hand and using actual dollartree foam. I doubt it will make that much difference in the end.

 

[Flitedesign 3d]

So far so good I think

So far so good indeed. How is the readi board compared to ft foam?

The a/b indicating is definitely too unclear when its not obvious which piece is the stationary piece about which the other piece folds. That's why I kinda switched over to just indicate the pivoting line with an arrow.

I realized this too late in the designing phase but the main plate is actually completely unnecessary, the engine pieces might as well attach to the wing bottom directly. This will be changed in the upcoming model.

The two skin pieces hanging off the base and the f7s belly skin are a bit challenging to bend and its recommended to glue them in 2-3 steps. Also don't worry if the seam between the base and f4s/f5s is not clean, it will be hidden by the leading edge extensions.

Remember to add the velcros before closing the bottom skins, you also need to make cutouts to the spar for the velcros, I forgot that in the plans.

 

[Oldrover TJ]

So far so good indeed. How is the readi board compared to ft foam?

I haven't worked with the new FT foams. The issues with the readi board that I've noticed are inconsistency in the thickness and slight waviness. It's almost like the foam has a grain.

Look what I got! hopefully I can get some good prints now.

I know it's been a while since I've been able to work on this plane. I'm hoping I'll be able to get some more done this weekend.

 

[Oldrover TJ]

OK time for a long overdue update. Sometimes I stretch these projects longer than I should. I've made some good progress and I've taken a few pictures.

Last I left off I had to 3d print all the plastic parts. That's all done now. I think when I inevitably make another plane I'll get some light weight PLA for the non structural parts. I also want to look into printing the canopy, since I'm pretty much incapable of making a nice looking one from foamboard.

And of course I need to have missiles. My friend found this model of an R-27 missile. I think it's gonna give this jet the extra touch...

Here's a rough layout of all the parts. I'm still trying to get a feel for how best to assemble everything and make it look good. I found that making things in larger groups seemed to work for me. I ended up cutting off and replacing the nose. I made the nose a few months ago and I guess I was really tired when I was working on it because it just looked awful. So I cut it off and replaced it. I'm much happier with it now.

I'm laying out the electronics and routing some of the wires through the fuselage before making the engine nacelle mounts. I was able to add the ESCs after assembling the wing. I actually ended up making two wings. The first one, I didn't align the upper skins well enough and the slots for the turtle deck were to wide.

I have really enjoyed this build. So far this is the most fun I've had building a plane. I just love the looks. Next is the big challenge of the engine mounts. That is a very complex piece due to the geometry changes. Fortunately I printed the lower intake ducts and that should help, though I'm not sure which is the left and which is right. I also need to make the thrust tubes and get the hardware for mounting the stabilators. I'll have more time to work on it in the upcoming weeks.

10/10 would recommend!

 

[Flitedesign 3d]

OK time for a long overdue update. Sometimes I stretch these projects longer than I should. I've made some good progress and I've taken a few pictures.
View attachment 225736 Last I left off I had to 3d print all the plastic parts. That's all done now. I think when I inevitably make another plane I'll get some light weight PLA for the non structural parts. I also want to look into printing the canopy, since I'm pretty much incapable of making a nice looking one from foamboard.
View attachment 225737 And of course I need to have missiles. My friend found this model of an R-27 missile. I think it's gonna give this jet the extra touch...
View attachment 225738 Here's a rough layout of all the parts. I'm still trying to get a feel for how best to assemble everything and make it look good. I found that making things in larger groups seemed to work for me. I ended up cutting off and replacing the nose. I made the nose a few months ago and I guess I was really tired when I was working on it because it just looked awful. So I cut it off and replaced it. I'm much happier with it now.
View attachment 225739 View attachment 225741 I'm laying out the electronics and routing some of the wires through the fuselage before making the engine nacelle mounts. I was able to add the ESCs after assembling the wing. I actually ended up making two wings. The first one, I didn't align the upper skins well enough and the slots for the turtle deck were to wide.
View attachment 225742
View attachment 225743
I have really enjoyed this build. So far this is the most fun I've had building a plane. I just love the looks. Next is the big challenge of the engine mounts. That is a very complex piece due to the geometry changes. Fortunately I printed the lower intake ducts and that should help, though I'm not sure which is the left and which is right. I also need to make the thrust tubes and get the hardware for mounting the stabilators. I'll have more time to work on it in the upcoming weeks.

10/10 would recommend!

Glad to hear you're enjoying the build, for the printed intake ducts, one side of it is significantly higher than the other, that higher side goes towards the center and the lower side goes towards the outside of the plane. Printing the canopy is a great idea to make life easier, I made it from foam to save some extra grams. I quickly modified the existing canopy to a 3d printable version, here are the files. Also those missiles look very nice, they give a nice touch to the plane