Twin edf SU-27

Captain Jay

Elite member
Im happy to announce that we have a successful maiden! I finished the build today by adding the tail and the leading edge extensions. I also added these extra intakes on the front, the real su-27 and most of the derived versions of it had these foldable intake grills to prevent stuff from getting sucked in on taxing, so sure enough Im using those as my advantage. Static thrust got increased by 200g. I planned to use 4 4s drone batteries at once since I have a lot of them but I kinda messed up the cg so Im using only 3. At least the wing loading is lower. Should have placed the fans 50 mm or so further back. Anyways, it flew really beautifully, feels really gentle in the air and it has a lot of power. A bummer it has only a flight time of about 2-2,5 minutes. I was supposed to fly two flights but unfortunately on the landing one of the pushrods got ripped out by the grass. Really easy fix though. Now the next step is to throw some paint and decals on this thing.

Oh and btw those mosquitoes really sucked...



Here are some numbers:
mass 1950g
thrust static 2350g at 120a about
wingspan:1010 mm (scale 1:14,5)
length: 1450 mm
edfs:12 blade
Batteries: 3x 4s 1,4ah 45c
esc: 2x hobbywing 80a
Servos: 2x emax es09md

Man, you are really good at this designing and building stuff. Great work!!! That thing flys so well!!!
 

The Hangar

Fly harder!
Mentor
Im happy to announce that we have a successful maiden! I finished the build today by adding the tail and the leading edge extensions. I also added these extra intakes on the front, the real su-27 and most of the derived versions of it had these foldable intake grills to prevent stuff from getting sucked in on taxing, so sure enough Im using those as my advantage. Static thrust got increased by 200g. I planned to use 4 4s drone batteries at once since I have a lot of them but I kinda messed up the cg so Im using only 3. At least the wing loading is lower. Should have placed the fans 50 mm or so further back. Anyways, it flew really beautifully, feels really gentle in the air and it has a lot of power. A bummer it has only a flight time of about 2-2,5 minutes. I was supposed to fly two flights but unfortunately on the landing one of the pushrods got ripped out by the grass. Really easy fix though. Now the next step is to throw some paint and decals on this thing.

Oh and btw those mosquitoes really sucked...



Here are some numbers:
mass 1950g
thrust static 2350g at 120a about
wingspan:1010 mm (scale 1:14,5)
length: 1450 mm
edfs:12 blade
Batteries: 3x 4s 1,4ah 45c
esc: 2x hobbywing 80a
Servos: 2x emax es09md
Absolutely beautiful maiden! I can't wait to build one!
 

Captain Jay

Elite member
I have done some great progress, only the tail and the leading edge extensions are missing. There are some 3d printed parts like the custom fan intake ramps, missile rails, tailcone and the stabilator- and servomounts. If everything goes well there will be a maiden tomorrow, the weather should be perfect like it has been lately. Its getting serious now!
Interesting, I see 3D printed parts. Perfect!!
 

Flitedesign 3d

Elite member
Its all painted now and I just finished adding the decals, Im using this $12 drag knife on my cnc platform, its amazing how nice decals one can make with such cheap accessory. When cutting with this incredibly small knife the cutting height must be perfect and the surface must be milled flat. Im using a hobby cutting mat on a face milled board and a 45 degree blade, have had good results with them. I went with the Russian knights colors, I like it and its much easier to paint than the camouflage ones which I also do like. Now its time to fly this thing a lot, first I need to get used to this new airframe and then gotta find the limits! I will cut together a montage ish video once I have enough footage. Here are some pictures of the finished su-27 and the whole family.
 

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Captain Jay

Elite member
Its all painted now and I just finished adding the decals, Im using this $12 drag knife on my cnc platform, its amazing how nice decals one can make with such cheap accessory. When cutting with this incredibly small knife the cutting height must be perfect and the surface must be milled flat. Im using a hobby cutting mat on a face milled board and a 45 degree blade, have had good results with them. I went with the Russian knights colors, I like it and its much easier to paint than the camouflage ones which I also do like. Now its time to fly this thing a lot, first I need to get used to this new airframe and then gotta find the limits! I will cut together a montage ish video once I have enough footage. Here are some pictures of the finished su-27 and the whole family.
Them jets look great. The SU is very nice...
 

The Hangar

Fly harder!
Mentor
Its all painted now and I just finished adding the decals, Im using this $12 drag knife on my cnc platform, its amazing how nice decals one can make with such cheap accessory. When cutting with this incredibly small knife the cutting height must be perfect and the surface must be milled flat. Im using a hobby cutting mat on a face milled board and a 45 degree blade, have had good results with them. I went with the Russian knights colors, I like it and its much easier to paint than the camouflage ones which I also do like. Now its time to fly this thing a lot, first I need to get used to this new airframe and then gotta find the limits! I will cut together a montage ish video once I have enough footage. Here are some pictures of the finished su-27 and the whole family.
Beautiful work!
 

The Hangar

Fly harder!
Mentor
Thanks, making these jets, especially the twins are really time consuming projects so it makes me particularly happy if they succeed.
@Skytalon Canards yes, I have some fun plans in my mind for further development of this jet, its such a performer, I have 5 flights on it now.
Glad to hear, I'm eager to build one if you put out plans!
 

Flitedesign 3d

Elite member

Here is a video of the su-27 in action, it truly is a fun jet to fly, I even almost crashed it once, Im glad I didnt. Btw would you prefer to see cut videos like this where I have cut some of the more boring parts out or uncut videos instead? Let me know!

Also, some of you have asked for plans, I have thought about it. The current version is far from being perfect and after seeing the flight performance I definitely want to develop a further version of this one, maybe a su-30? This will be a project for another time though, maybe next summer, because it means I need to scrap the current one for the electronics and Im not willing to do it yet. Also I got a tomcat to finish this summer. This is why I have decided to release the current plans as “alpha version” for the potential people that want to make one. Just give me one more week to fix some of the bugs I found along the way and I will release them.
 

Oldrover TJ

Active member
Oh man, I'm so excited! For the plans and future plans. She flies great.

I guess I have some jets to fly too aggressively this week to get ready.

edit:
As for the videos I liked seeing the edited version. On the other hand I get more of a feel about how the plane performs when the video it unedited.
 
Last edited:

dehager

Well-known member
Congratulations, she flies great!!!
What material did you use for your printed parts and how have the parts held up?
 

Flitedesign 3d

Elite member
What material did you use for your printed parts and how have the parts held up?

Generally I prefer to use petg due to its greater ductility, toughness and temperature resistance compared to pla, but for this application pla is definitely good enough. When talking about foam board airplanes the mechanical properties of 3d printed plastic will rarely the limiting factor. The stabilator- and servo mount is the only structural part and I printed that with 4 perimeters I think, its definitely strong enough. Parts like the intake ducts I printed with one perimeter and 5% infill to save weight and they are well strong enough for what they are designed for. I will include a list of the key parameters in the plans.

@Oldrover TJ Im using 2750kv fans, its the 4s version and I recommend anyone sticking to 4s instead of 6 if making a hand launch jet. Since Im already pushing the limits of my batteries 6s would require roughly 50% more batteries by weight after which you might want to add a cf wingspar due to the additional forces on the wings when pulling G's. 6s mainly results in higher wing loading, higher speed and a larger coss-sectional area in the duct to make use of the power.
 

Captain Jay

Elite member

Here is a video of the su-27 in action, it truly is a fun jet to fly, I even almost crashed it once, Im glad I didnt. Btw would you prefer to see cut videos like this where I have cut some of the more boring parts out or uncut videos instead? Let me know!

Also, some of you have asked for plans, I have thought about it. The current version is far from being perfect and after seeing the flight performance I definitely want to develop a further version of this one, maybe a su-30? This will be a project for another time though, maybe next summer, because it means I need to scrap the current one for the electronics and Im not willing to do it yet. Also I got a tomcat to finish this summer. This is why I have decided to release the current plans as “alpha version” for the potential people that want to make one. Just give me one more week to fix some of the bugs I found along the way and I will release them.
That was a nice flight. The Su performes great. Haha almost ate some bushes on the extra video part at the end. Glad it has the power to pull out of trouble. Many jets don't. It has a very big woooosh sound when it goes by. Very cool!!