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Old Aug 03, 2011, 11:54 PM
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Mini-Review
UMX Sbach

I just had to add one of these to the hangar.

The Sbach flies much differently than the Beast, as one would expect. Similar to a more aerodynamic Sukhoi XP on steroids - but much, much smoother in the air, and with razor-sharp tracking & more precise controls. It flies much 'bigger' than it is. Even bigger than the Beast. More like a 40-size plane than a UM. In stock trim, it has unlimited vertical. It is a very capable aerobatic machine, that can perform any pattern maneuver in the book. With the SFGs, it can also perform most 3D maneuvers - however hovering is not its strong suit. With the CG at the sweet spot, it has no bad habits. Bring her in hot, or raise the nose & bring her in slow. Without the SFGs, she lands a bit hotter than the XP or Beast. With the SFGs, she can slow to a crawl & remain fully controllable - with no wing-rock at all.

The airframe really comes alive with a Hyperion 180 or 240 mAh 2s pack & a GWS 5030 prop. In my opinion, the 5043 is a bit too much for this motor. At my elevation, it's just barely faster than the 5030, and vertical performance & flight-time are far poorer. Plus, the motor was too hot to touch after a 30-sec static RPM test. With the 5030, the motor was barely warm after a 30-sec static test. Others who have used the 5043 say that it doesn't run hot in flight, however. At higher altitudes, the 5043 may prove to be the best choice.

This is another UM that has a marginal CG. Some samples are a bit nose-heavy with the pack all the way back, while others are not. Mine was sligthly nose-heavy, even with my 11.4g Hyperion 180 2s pack all the way to the rear of the battery tray. To move the CG to the sweet spot with the Hyp 180 2s, I had to add 0.7g of tail ballast. The sweet spot on mine seems to be 37-38mm aft from the LE, as measured from the wing root. It is still just a tad nose-heavy (36mm CG) with my homebrew Hyp 240 2s packs.

Here's my maiden flight:

Eflite UMX Sbach 342 maiden flight (17 min 19 sec)


And here's my performance demo flight, with the 5030 and my homebrew Hyperion 180 & 240 nmAh 2s packs:

UMX Sbach performance demo (15 min 52 sec)


Stay tuned for more info - including static RPM testing, Doppler speed run results, and more.


EDIT 09/04/11:

I am now using 1g of tail ballast, which allows me to move the CG slightly aft from the neutral point with my 14.6g homebrew Hyp 240 2s packs.

I have now flown with both sets of SFGs. The smaller set transforms the plane! High-alpha flight is trainer-easy. She is so stable in harrier, one can simply haul the stick back & 'drive around' on the rudder, controlling altitude solely with throttle. Harrier landings are so easy, a caveman could do 'em! KE harriers & KE loops are effortless. With the large SFGs, I didn't even need full rudder for KE loops. I did notice a bit of roll-coupling at higher rudder deflections, though. Here are a couple videos with the SFGs:

Having fun at the park in the wind. High alpha, harrier landings, and general goofing around:

Fun with the UMX Sbach + SFGs in the wind (7 min 52 sec)


An ideal flying day at the field. Small & large SFGs. High-alpha, harrier landings, KE, KE loops, and general goofing around:

UMX Sbach with SFGs - high-alpha, KE, KE loops, harrier landings, etc. (9 min 7 sec)


EDIT 09/17/11:

Here's some static RPM data using the stock 180 mAh & my homebrew Hyp 180 & 240 mAh 2s packs. RPM taken under natural light with a calibrated optical tach, 30 sec into each run on a freshly-charged pack:

Elevation: 910 ft AMSL
Temp: 70 F

-------- Eflite 180 - Hyp 180 - Hyp 240 - Thrust (g)* - Speed (MPH)**

Eflite V3 --- 9,570 ---- 10,400 -- 10,560 --- 80/96/99 ---- 24.9/27.1/27.5
Eflite V4 --- 9,510 ---- 10,380 -- 10,530 --- 79/95/98 ---- 24.7/26.8/27.4
GWS 5030 - 9,960 ---- 10,860 -- 11,000 -- 96/115/118 --- 28.3/30.8/31.3
GWS 5043 - 7,900 ----- 8,540 --- 8,880 --- 84/99/108 --- 32.2/34.8/36.2

*Calculated using the GWS prop spreadsheet
**Calculated pitch-speed. Prop slippage and in-flight unloading not taken into account.

Joel
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Last edited by turboparker; Sep 17, 2011 at 05:21 PM. Reason: Added static RPM data
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Old Sep 13, 2011, 07:25 PM
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Looks good! Just don't know if I really want to shell out for one, though.
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Old Sep 16, 2011, 08:34 AM
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Thanks for the videos TP.. Looks like it's a lot of fun to fly!
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Old Sep 17, 2011, 12:24 PM
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East Bethel, MN USA
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Bryan,

Thanks! She flies even better than she looks! If you're comfortable flying high-performance pattern ships, you will absolutely love the Sbach. She flies straight as an arrow, and goes exactly where you tell her to go - with no coupling at all.

BC,

You're welcome! Yeah - she's a blast to fly! She definitely has the widest flight envelope of all the aerobatic UM ships. With the SFGs, she can slow to a crawl & remain perfectly controllable, and she can do all sorts of 3D. Take 'em off, and she turns into a pattern ship. She can also handle 10-15 MPH winds - provided the pilot has the skills.

Joel
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Last edited by turboparker; Sep 27, 2011 at 08:17 PM. Reason: Syntax error
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Old Sep 27, 2011, 07:44 AM
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Hey Joel,

Thanks for your feedback on this...how would you say the Sbach handles the wind in comparision to the beast?

Also, whats the difference between the two different SFG's that are provided?
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Old Sep 27, 2011, 08:31 PM
Gopher huntin' stick jockey
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East Bethel, MN USA
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Quote:
Originally Posted by Brooklynstar23 View Post
Hey Joel,

Thanks for your feedback on this...how would you say the Sbach handles the wind in comparision to the beast?

Also, whats the difference between the two different SFG's that are provided?
Brooklynstar,

You're welcome! Glad I could be of help.

Which is better in the wind? That's a tough one. They both handle the wind way better than any of the other micros - with the Sukhoi XP close behind. In a headwind, it's easy to 'hover-land' either one. The Sbach penetrates the wind better than the Beast, but the Beast tends to stay planted on the runway better than the Sbach.

Regarding the two sets of SFGs - it's a matter of preference. The larger set just provides more side-area. I prefer the smaller set, as I noticed a bit of roll-coupling when I used the larger set.

Joel
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Old Sep 28, 2011, 12:33 PM
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Thanks for the insight Joel.

Is a con of an SFG usually roll coupling? On my new scratch build DS wing I have small wiglets on. Was actually wondering thing morning what it would do if I put larger ones on?
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Old Sep 28, 2011, 09:42 PM
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East Bethel, MN USA
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BC,

Typically, SFGs do not cause roll-coupling. At very high rudder deflections, my two Sbachs have a bit of roll-coupling without them. Not sure why the larger SFGs seem to magnify the effect. The biggest con of using SFGs is that they make it difficult or impossible to side-slip or crosswind-crab, which rules out crosswind landings.

Joel
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Old Jan 03, 2012, 06:29 PM
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Do you know how to do a harrier with this plane?
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Old Jan 04, 2012, 12:07 AM
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Quote:
Originally Posted by Luke98 View Post
Do you know how to do a harrier with this plane?
Luke,

Check out the videos I posted. I do quite a bit of high-alpha flying with the SFGs on.

Joel
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Old Jan 04, 2012, 05:31 AM
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Did you try a 6030 on it?
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Old Jan 04, 2012, 01:55 PM
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Quote:
Originally Posted by BryanEW710 View Post
Did you try a 6030 on it?
Bryan,

Based on 5030 & 5043 flight-reports & static RPM data, the 6030 would be too much prop for the stock setup. Plus - ground-clearance would be a problem. Given the above, I saw no reason to test it. The HT's 5.5x2 prop & the Gee Bee's 5.25x3.5 prop may be interesting options, however. If I remember correctly, someone also reported having good luck indoors with the GWS 5x3x3. Although I have no trouble flying WOT circuits indoors in the space of a soccer court on the 5030 + Hyp packs, I spend most of my time @ 50% throttle or less. A prop that fully-absorbs the motor's torque at a lower airspeed would be desirable when flying indoors, however ROG takeoffs from the AstroTurf at our indoor site would likely be impossible with the 6030. The HT's 5.5x2 or the GWS 5x3x3 would likely be better candidates for indoor flying.

When it comes to flying the Sbach outdoors - I'd actually like a bit more speed than what I'm getting with the 5030 + Hyp packs. I plan to install the 3000Kv motor & re-prop accordingly.

Joel
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Old Jan 04, 2012, 02:05 PM
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Quote:
Originally Posted by turboparker View Post
Bryan,

Based on 5030 & 5043 flight-reports & static RPM data, the 6030 would be too much prop for the stock setup. Plus - ground-clearance would be a problem. Given the above, I saw no reason to test it. The HT's 5.5x2 prop & the Gee Bee's 5.25x3.5 prop may be interesting options, however. If I remember correctly, someone also reported having good luck indoors with the GWS 5x3x3. Although I have no trouble flying WOT circuits indoors in the space of a soccer court on the 5030 + Hyp packs, I spend most of my time @ 50% throttle or less. A prop that fully-absorbs the motor's torque at a lower airspeed would be desirable when flying indoors, however ROG takeoffs from the AstroTurf at our indoor site would likely be impossible with the 6030. The HT's 5.5x2 or the GWS 5x3x3 would likely be better candidates for indoor flying.

When it comes to flying the Sbach outdoors - I'd actually like a bit more speed than what I'm getting with the 5030 + Hyp packs. I plan to install the 3000Kv motor & re-prop accordingly.

Joel
Gotcha. I suspect that I'd need to re-motor and -prop this bird to fly the way I prefer to fly (low and slow). Speed is not the name of my game
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Old Jan 04, 2012, 03:32 PM
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Originally Posted by BryanEW710 View Post
Gotcha. I suspect that I'd need to re-motor and -prop this bird to fly the way I prefer to fly (low and slow). Speed is not the name of my game
Bryan,

Maybe a month or so back, someone on the Sbach thread installed the V1 Beast's 2300Kv motor just for that purpose, and reported good results. You may want to search the Sbach thread. The HT's 5.5x2 prop aught to be a real stump-puller on the 2300Kv motor, and should be be great for slow-flying. Loading should be relatively light, given that the HT uses the same prop on the 2500Kv motor. The 5x3x3 should also work well for slow-flight. If I remember correctly, the person who reported favorable results with the 2300Kv motor also had good luck with the 5x3x3.

BTW - I also enjoy flying low & slow, but I have other 'tools in the toolbox' for that - such as the B3D, Mossie, J3, and Champ. Although the Sbach can fly quite slowly, it seems to be much happier when flying 'up on the wing'. Currently, the B3D is my go-to plane when I want to fly low & slow with an aerobatic ship. The Champ is my go-to plane for serious low & slow flying. There's something about a Champ or Cub flying just above stall....only a wingspan or two high, that makes me grin from ear-to-ear!

Good luck with the swapping & let me know how it works out!

Joel
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Old Jan 04, 2012, 03:38 PM
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I'm still trying to talk myself into the Sbach. I enjoy my stock Su-26XP, but also have a pair of Common Sense Yak-54EP's that I enjoy hovering and harrier-ing. I'm really only wanting to buy the Sbach if it can be made to fly like one of the bigger planes (the XP, of course, doesn't really like high-alpha in the way that the larger planes do). In other words, there's no reason to move to the Sbach if it's going to essentially be a larger, faster, and heavier XP, you know?
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