Big Su 34

[19000rpm]

I've always been a fan of the big, twin, 64mm Freewing Su34 since it came out a couple of seasons ago. Well, Banana Hobby had an ARF for just $169 bucks. They had me cold.

The plane arrived yesterday in near pristine condition needing only the 7ch radio and a 3200 4S to complete. The paint job is very good.

This was one of the first, 3D capable, production EDF's. Flips, flat spins, inverted flat spins, tumbles, etc. are possible. It may even hover. If not; power upgrades will make it hover capable.



As with the entire Freewing line; this plane is a snap to put together. Fit is always good and the reliability of the electronics: excellent. I won't bore you with the details.

Notes:

I always add an external 4-5A BEC to these types (high number of servos) when one isn't supplied with the model.

The only design flaw, as far as I'm concerned, is that the EDFs are not removable with out foam surgery. Freewing has corrected that on the subsequent models in the line.

Some departure of accuracy, from full size, are the non functional canards and lack of a full flying horizontal stab. Both of those could be easily done and I may look into that later on.

The Su 34 has mechanical retracts, as do some of the other freewing models. I haven't been a big fan of those. Although, I've found increasing the retract servo throw, about 30%, after they are mechanically tight, increases the no-fold reliability tremendously. There are always servoless electric retracts as an upgrade.

I'll report in with details as the come up.

[19000rpm]

I ordered the HK servoless retracts. Two sets: one for the Su34 and one for the F35. Both come the same plastic mechanical retracts.

The F35's nose wheel mechanical retract only stays extended if I set it down like a falling leaf. Which I can do about half the time. The other 50% are chin scrapers. The mains are more reliable. They didn't have my confidence for lasting very long though.

The Su34 remains partially built until the retracts arrive.

I anticipate this is going to be a nice flying plane. Good 3D and decent speed. I'll likely upgrade the 64mm fans with CS10 blade 70mm fans at some point. That should pretty much guarantee a good hover!

[19000rpm]

The etracts have arrived and have been installed. The process took a little time to get right, the nose retract in particular because of the nose steering, but not anything that an average builder can't manage.

I didn't take any photos of the project, but I did document the F35 conversion for another forum. Let me know if there is any interest and I'll post those photos.

For now I wait on the weather for a taxi test and maiden.

[Doozer]

post 'em up. I don't think I'll ever own one but I like looking at others handy-work. Very cool looking plane.

[19000rpm]

Well, Tomorrow looks like the day for the maiden. I'm looking forward to this a lot.

As far as the F-35 etracts go: I flew the plane 3 times and every time I flew it the nose gear hung up. I couldn't seem to duplicate it on the ground. When it hung up, about half way, in the air I was flying it in every way to get it loose. Right side up, upside down, vertical, knife edge. Toggling the switch like crazy. Nada. The first time I decided to land it in the grass. I expected the nose gear to fold but it didn't. Picked it up, cycled the gear and it retracted. Turned the plane upside down and it retracted. Put in another pack. Repeat. Cripes! Put in third battery. Repeat except this time it finally lowered all the way for the landing.

I'm pulling the gear and putting some compressed air though the mechanism to see if there might be a small piece of crud stuck in the somewhere. I hope this doesn't happen with the Su34 tomorrow...

[19000rpm]

Here's how the etracts were installed on both the Su34 and F35.

Remove stock retract and servo. Remove foam as required for etract.



Etract. Mark strut to cut to proper length for new landing gear set up.



Struts, oleo, gear and wheel prior to cutting.



Steering arm using etract steering arm and stock steering arm mated.



Another view of steering arm. Note aluminum tape wrapped around strut to increase diameter to match oleo.



etract assembled with gear.



etract retracted.



etract extended.

After further inspection of my stuck retract on the F35 I discovered it was stripped. Carp! Ordered a new one. The Su34 version working fine.

[19000rpm]

The Maiden:

Here's a few shots before I put her in the air the first time.





Location: HS Running Track; 10 AM
Usually I do a taxi test and range check on a day prior to the maiden. I usually uncover an issue or two. Today I rolled it all into one session. With decent weather coming to an end soon I need to make the most of the flying days left that require a good airstrip. And, since I uncovered no issues, I was good to go. Wind NNW 5-10.

Slight trepidation
Putting in the etracts I ended up with a slightly different height off the ground from stock, but the angle of attack, sitting on the ground, was about the same. I was a bit concerned that the difference in stance may keep the plane in ground effect too long, making for late rotation. I could run out of room. Visions of going off into the weeds at 80 mph and the etracts ripping off crept into my mind's eye.

Full Throttle
I slowly advanced the throttles and soon was at full tilt with both 64mm fans screaming, blowing dust and debris off the track.

I pulled slowly back on the stick and she rotated smoothly into the air in a few hundred feet. No trip into the weeds. No big jump like I've seen on some Su34 vids. Sweet!

But how will it fly?
After climb out to 3 mistakes high; we made one gentle turn and I flipped the retract switch. They worked! No hang up on the nose like the F35. A victory roll to celebrate!

I pulled the throttle back to 3/4 and made a circuit checking the trim and reaction to stick input. The elevator needed too much up trim. Made a mental note to move the battery back a little. Maybe add some ballast.

The response to aileron and rudder were crisp. I did a few more rolls and coordinated turns. It was time to trip the TV switch.

Intruder Alert!!
About this time I noticed some other citizen had the temerity to be using "my airstrip" like it was a place that could be used for the purpose of running. The Nerve!!

Back to business
I flipped the TV switch. Full up elevator and she flipped almost within her length. Perfect! Now for full rudder with a touch of elevator. A nice flat spin. Let go of the sticks and she straightened herself out.

I made a few full throttle low passes. No barn burner, but fast enough to not be a slouch and slow enough to appreciate her beauty. Went inverted once and then put the wheels down for an inspection pass. Wheels locked full down. Good for final approach.

How will we do with the landing?
I lined her up, dipped between the trees and crabbed against the crosswind toward the tarmac. Then, I noticed runner boy on a collision course with my landing maneuver. Oh shucks, the battery is getting low. I better put her in the grass. Which I did.

Touch down was a two pointer, mains first, and a short roll out to settling on the nose wheel. Couldn't have been nicer. Runner boy gave me a wave. I guess he's not such a bad guy.

The kind of day we all live for
Well, there you have it. I had a great time and have nothing bad to report or any repairs that need done. Adjust the CG a bit. That's all. It doesn't get much better than that.

[Doozer]

I think I know that runner. He was the same one that came out of the blue and made me crash my Stinson. damn YOU!!!!

Great maiden story! Made me laugh ("intruder alert") Good lookin' plane. You need a helmet cam.

[19000rpm]

Just a quick update. I added rudders to the Su34. I wanted to improve low speed handling in gusting crosswinds. The TV takes too long to react and adds forward movement which I don't necessarily need on final. I haven't had a clear field (snow) to test it on yet.