Ultra fly SU-27 Questions and tips

[dblnaknak]

I just opened my box and realized that the instructions suck. 1st question-is the clear bottle the glue? 2nd-where do you install the speed controller so it stays cool? I cant find a gws mega mount, so will a himaxx 2025-4200 provide enough power for this large plane, also what gearing should I use. Any help is good help.

[David Hipperson]

Haven't tried the SU-27 yet but sounds like the instructions are the same quality as the F-16, in other words useless. You can make sense of them but go through them several times and if you are not experienced think three times and then glue. Much as the Ultrafly glue is not bad (yep! stuff in the clear bottle) I'd recommend epoxy for the high stress areas such as main fuselage joints and wing joining etc. If you do, then pierce the mating faces with a sharp pencil (just poke the tip 6mm into the foam) then spread epoxy onto both faces working it down into those holes. A pop stick is good for this. Then join the faces. 1" wide making tape is excellent for holding the glued items together - peel off carefully afterwards. The really important thing is to get the two wings aligned not only with the fuselage but also with each other. Use a slow setting epoxy such as 30 minute and take your time to eyeball from both back and front. If the 27 is the same as the F-16 then weight the fuselage down on a flat level table top and make up either two identical wooden blocks (balsa is fine) or even two identical card formers to support the wing tips while the root joint sets. Do some dummy runs and you'll get the idea.
Have flown my F-16 on the original motor and on the Himark 2015-5400 on the 4.5:1 gear and it's fine either way so your Himark should be OK other than extra weight at the tail. You may need some ballast in the nose. Also if like the F-16 treat the CG with care as Ultrafly have it fairly well back and a few mm further forward does not hurt especially on those first flights.

[dblnaknak]

can anyone tell me where the installed the speed control. Also which wires do you extend.

[Big Zagi]

Hello, I have lengthened the wires from the speed control and put it forward in the receiver comparment. I have vented it and put as much forward as possible to balance. I like David's idea of using the holes and slow epoxy for the wing alignment attachment. I'm using a Zagi pusher motor which bolts up to the stick mount to start. I may go brushless w/3s2p 2100 lipo.

Your comment about the instructions is true, but it is not difficult to assemble. How about the plastic skid pan? Very heavy, but I would worry about landing even in the grass without it.

[David Hipperson]

On the F-16 (sorry to refer back to that in this thread) I glued the foam belly onto the upper fuselage after setting everything up. Square access hatches were cut through this foam belly so that I could get to the servos, aileron adjustments etc. Then four small 6 X 6 patches of 3mm ply were epoxied into the foam two at the front and two at the rear and the whole plastic belly pan became a removable hatch cover with small screws going into those plywood squares. Also a 10 X 10 X 30mm pine block was epoxied flush into the foam belly pan with a screw in hook for bungee launches. This works well but the hook has to be removed to take off plastic belly.
Don't know what the Sukhoi is like but a couple of appropriately placed holes to get air over the ESC isn't a bad idea either. Extend the wires from the ESC to the motor not the wire to the battery.

[Holtenbacker]

My SU-27 arrived via Tower-Reno this afternoon.
Looked at the instructions and they kept talking about my lunch. :D
I don't like to fly on an empty stomach. :)
I decided to look here for any suggestions or mods that work?
I'll be using an available Himax 2025-4200 & CC-25.

[dblnaknak]

I thought about using the himaxx, but I figure it might be a little under powered. I am waiting for the GWS stick mount for the MEGA 6 turn.

[Suntzu]

Im starting my build this week. I have the included little brushless unit. Id love to see a thread on construction and tips as the instructions are a bit sparse...

[David Hipperson]

I agree that the instructions can be irritating but you'll get the idea if you read three times, try the part twice and then glue. Do your best to think your way through each phase and if you can try to look ahead for any prospective problems. To be fair to Ultrafly there are not likely to be many as the product is good but they make too many assumptions about what we know as buyer/constructors. Incidentally though the glue supplied is very good you'll find that both 5 min and 30 min epoxy can come in handy. Also, although these seem to be a very quick build be prepared to glue and wait. You'll find it's worth it.
One thing that does concern me a bit is the power that is being put into this type of model. In this and other similar threads the power levels are being increased to very high levels. Whether this is wise seems to be a moot point. As an example, we are still looking at models where hinges are glued into relatively soft foam and flutter is not an impossibility. The supplied brushless units are quite powerful and provide great performance but I'm inclined to think that going further could create problems. I hope I'm wrong.

[Holtenbacker]

I thought about using the himaxx, but I figure it might be a little under powered. I am waiting for the GWS stick mount for the MEGA 6 turn.
The 2025 will put out @ 13-15A, anywhere from 26-36 oz thrust.
The SU-27 is supposed to be 21 oz ready.
You were probably thinking of the 2015.