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Old Mar 05, 2012, 05:28 PM
the anthropocebo effect
kcaldwel's Avatar
Joined Jan 2007
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e-Taborca first flight

It has fins, so I hope this is OK here.

I had a successful first flight on my LET Taborca:

http://www.letmodel.cz/gallery-taborca.htm

Mine is a bit older one than in the photos on the web page. We had some camera issues today, but hopefully there are a couple of shots coming. I'll try for some more photos tomorrow.

It was a bit windy this morning, and supposed to pick-up, but it seemed ok to give it a try. I had added 70 grams additional nose weight, on top of the 260g MVVS 5.6/960 Redliner motor (14x9 CF folder, 80A HK Plush ESC, 5A outboard sBEC), and the 6000mAh 3S Nanotech battery, just for insurance. I had eventually got all the flight modes programmed into my JR9303 (my first model on this Tx). It is a bit of a beast at 3.3m span, and 4.0kg ready to fly.

Anyway, it flew straight off a hand launch, and climbed out nicely. I kept it pretty straight for the first bit. It responded very nicely to the controls, and basically only needed a couple of clicks of up trim, probably due to the CG being slightly forward of the recommended spot. I shut the motor off at about 200m, and tried out the thermal and speed modes and full aft stick. Everything seemed perfect, and it flies much like a conventional big glider.

I stumbled into a nice thermal, and managed to climb out while feeling out the controls. An aggressive looking bald eagle joined in, but even though it is mating season, he just climbed up with me. Even with full aft stick it wouldn't drop a tip or stall, so the CG needs to go back a bit.

I did a bit of a dive test - confirmed nose heavy - and tried out the landing flaps. They slow it down and steepen the glide path quite nicely. It really scoots in speed mode too. I need some reflective tape on the leading edge. It tends to disappear with the small frontal area.

It was a bit turbulent down lower, but the Taborca handled it nicely. The landing flaps worked quite well, and it hand a smooth touch down right on our grass strip. One of the easiest first flight I've ever had, including a thermal climb. Considering it is a 4kg, 6 servo flying wing, I am very impressed.

It is going to be difficult to hand launch myself I think, just because of the weight and size. The climb rate is not blistering with the present set-up. It might make 200m in 30 seconds, I'll have to throw the altimeter and cut-off in it for tomorrow. It is at about 58A, 600+W at the moment. I might try a 15x9" prop, but I'm not sure I want to push the motor much harder than that.

It is a very nicely built model (obechi over white foam, fibreglass fuse and winglets), and it flies very well. I hope I can figure out how to hand launch it myself - it would make a very interesting ALES glider.

Kevin
Courtenay, BC
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Old Mar 05, 2012, 06:06 PM
Herk
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Old Mar 05, 2012, 06:27 PM
I don't like your altitude
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Congrats.Looks like you've backed a winner.
Stuart
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Old Mar 05, 2012, 09:34 PM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
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Of course you plane belongs here. I just mis-named the forum... my bad.

Your flight report reads like a novel ! Was it really that nice. Not only do I want your plane, but I also want the flying site and that eagle too.

I'd be interested to know the final wing loading. You might try launching with a bungee. It is a great way to definitely get airborne in a small space. Use a forward tow hook.

Kent
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Old Mar 05, 2012, 09:58 PM
the anthropocebo effect
kcaldwel's Avatar
Joined Jan 2007
3,467 Posts
It really was the easiest first flight I've had. I was a bit worried, because it is a big, heavy, complicated airplane. To make this sound even more unbelievable, I was given the Taborca by an incredibly nice guy. He had lost one because of flutter breaking a control rod, and decided he wasn't going to fly this one. I used M3 hardware, aluminum servo horns, big ball links, and JR digital servos to try and avoid that.

I am glad I landed when I did though. I had used my usual semi-sticky vinyl tape at the wing to pod junction, and one wing had worked it's way out a bit. The control connections are automatic with 9 pin D-subs, so if the wing had come out a bit farther, it could have been very bad. There are snaps that are supposed to hold the wing on, but perhaps the ones on this pod aren't quite right. I repaired the broken pod and I'm using it for the early flights at least, and saving the shiny new one for later.

We do have a great field: wide open, flat, snow capped mountains and a glacier to the west, lots of eagles, and trumpeter swans during the winter. It is a bit mushy now from the winter rains, and the runway is a bit rough, but it is very nice. And usually only two of us out flying.

The wing loading is 47.3g/decimetre^2, or about 15.5 oz./sq. ft. It weighs 4.0 kg (140.8 ounces), and has 84.5 sq. decimetres (9.1 sq. ft.) of wing area. It uses the MH45 airfoil. The winglets are very tall. Most of the specs are in here:

http://www.letmodel.cz/technical-data/taborca.pdf

I am still amazed at how easy it was, I never touched the trims until after I landed, when I added a few clicks of up because I had held a bit during the climb.
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Old Mar 05, 2012, 10:02 PM
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ohmite's Avatar
Eden NY
Joined Sep 2001
540 Posts
Kevin,
I've always admired the Taborca since reading of Jochen Haas's development in "On the Wing". He provided some good Excel spreadsheets at the time to help others design similar gliders.

Looking forward to seeing your pictures and video soon. Please keep us informed. Do you intend to do any flight testing to correlate its performance with prediction software or do you just intend to enjoy flying it?

Best Regards,
-Eric
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Old Mar 05, 2012, 10:23 PM
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Knoll53's Avatar
United States, CA, Marina
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Quote:
Originally Posted by kcaldwel View Post
The wing loading is 47.3g/decimetre^2, or about 15.5 oz./sq. ft. It weighs 4.0 kg (140.8 ounces), and has 84.5 sq. decimetres (9.1 sq. ft.) of wing area. It uses the MH45 airfoil.
This is really a great size and weight glider. It must fly with "authority". I've got the same airfoil on my Horten and there are no complaints. I hope we see some video some day.... and don't forget the eagle!

Kent
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Old Mar 06, 2012, 06:53 AM
Red Merle ALES
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United States, Mt, Helena
Joined Apr 2002
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Kevin,

Congratulations on the successful test flight! I've always liked the planform, taper and sweep of the Taborca. I'm awaiting your ALES test and the photos/videos.

Curtis
Montana
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Old Mar 06, 2012, 07:09 PM
the anthropocebo effect
kcaldwel's Avatar
Joined Jan 2007
3,467 Posts
I flew the Taborca for maybe an hour and a half today, all thermalling and fooling around. It thermals quite well, and I had several 30 minute flights from a 30 second motor run. I had to burn off altitude on a couple of occasions, because I was getting some frame losses. I'll have to do a bit better job of antenna placement than stuffing them in the back somewhere. I like that the FrSky system warns you real time.

The powered climb rate seems better than I thought yesterday. It is just a big airplane and doesn't get small real fast! I have some altimeter traces, so I'll see what it looks like. It was very active today, so decent measurements will need some early morning flights.

I'm photographically challenged, but Murray manged to get some pics with my point and shoot. He even got some video of my first self hand-launch (a bit exciting), and my worst landing. I'll figure out how to put those up tonight.

It would make an interesting ALES glider. It has great speed and a very good glide. The sink rate is a bit high, and the thermal turn diameter is a bit big for weak days, but I guess that might be expected for a 4kg (140 ounces) glider. For a strong day with wind like today, it is a very good glider to fly. I'm very impressed with the glide at speed. The landing control with the flaps is quite good for ALES style landings.

Hand launching went OK with a bit of wind today, and I'm now sure I can do it even in no wind. It is heavy, and has a big span, so it is harder to get it balanced, and it requires a good throw. You have to keep your hand clear of the flaps. It would certainly intimidate the other launchers in ALES!

I took out about 20g of the nose weight I had added, and I'm pretty happy with the CG there.

The Taborca is a very well designed and constructed glider. It looks very cool in the air, and is a lot of fun to fly. It is very responsive to the controls. It does nice loops too!

No eagle pics today, they were mostly at 4,000', or going that way pretty fast. You'll have to settle for my local pair from my front yard. They nest behind my house. The first red tails were back today though, so despite it being pretty cool today, spring must be on the way.

Kevin

Edit: I just measured the powered climb rate, and it looks like about 450m/min. It gets to 200m, with considerable ranging, in about 27 seconds. It's just so big, I originally thought it was only at about 150m, when it was actually at 200.

Not bad for a 4 kilo glider.
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Old Mar 06, 2012, 10:58 PM
the anthropocebo effect
kcaldwel's Avatar
Joined Jan 2007
3,467 Posts
Here is a poor (but at least short!) video of my first go at hand launching this 4 kilo beast myself. I threw it upwards a bit on the later launches, and I didn't get the descent. It is easier on the nerves that way!

First self hand-lauch of 3.3m span, 4kg flying wing Taborca e-glider (0 min 13 sec)


I'll use HD, and actually put a title on it if I do this again.

Kevin
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Old Mar 07, 2012, 12:33 AM
Carbon fiber is our friend
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United States, CA, Lodi
Joined Feb 2001
4,089 Posts
That looks great!
I had a couple flying wings I built for thermal back in the late 90's. They were prone to spinning on winch launches, which could sometimes be saved by stepping away from the pedal. If I didn't get off it, it usually crashed Otherwise they had excellent overall performance and I think ALES might be a good reason to resurrect them.

Thanks for sharing.
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Old Mar 07, 2012, 10:37 AM
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Knoll53's Avatar
United States, CA, Marina
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I like your videos and that is an amazing flying site. I am so so jealous.

If I haven't mentioned it already, a short bungee launch takes all of the worry out of launching these big ships. I use a doubled up high start tubing, maybe 20' long, pull in back to 20lbs and this will get my 5lb. Horten up at least 50'. Use a forward tow hook location. Lothar has posted some good videos of this technique with his big Colibri. My avatar is me leaning against the bungee, ready to launch.

Kent
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Old Mar 09, 2012, 01:49 PM
the anthropocebo effect
kcaldwel's Avatar
Joined Jan 2007
3,467 Posts
Here is my JR XP9303 (Heli) program that I have been using on the Taborca successfully. I do plan on revisiting this as I learn a bit more about programming the 9303. This was my first airplane with this Tx, and I'm pretty sure I can improve it.

It is a 5 flight mode set-up. I have a Launch mode, where it is in climb trim and the motor is active on the left stick. There are three flight modes: speed, cruise, and thermal, all with different flap settings. And a Land mode, that starts at the Thermal/slow flight setting, and the flaps are active on the left stick.

Note that the flaps go "backwards" from the normal convention. They deploy more as you move the stick from the bottom up (low throttle to high throttle). I have been setting up all my e-gliders like this, so that throttle off and flaps off are both with the stick at the bottom. I think this is the best way to do it, so that you don't suddenly end up with full throttle or full flap when moving the flight mode switch.

The Launch, Flight Mode, Land switch is on the upper left 3-position switch on my Heli Tx. The Speed, Cruise, Thermal modes are on the right 3-position switch. The launch and Land modes over-ride the Flight mode switch, so you can switch to Land or Launch modes with just the one switch.

The issues I have right now are the right flap slider is active, so I taped it off in the lowest position to avoid unwanted flap trim. And I do not have the rudder action programmed that is in the Taborca guide. It is basically a drag control - the outer two control surfaces go opposite ways to just make drag on one wing. I didn't think that was really much help for thermalling.

I am very used to using Flight Mode settings for my flaps from my DLG set-ups, even though they weren't called that on my old 8103, so this works well for me. If you use this program, make sure you understand what the switches are going to do before you fly.

I've attached a pdf version, and the original Excel version (zipped) so you can modify it or use it to record other airplanes.

Kevin

Edit: I better add which control surface is connected where. The channel assignments are different in Glider mode than Acro.

1 = left combi-flap (middle flap)
2 = right combi-flap
3 = right elevator (outboard flap)
4 = left elevator
5 = right flap (inboard flap)
6 = left flap
7 = motor
8 = sBEC
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Old Apr 23, 2012, 04:53 PM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
1,114 Posts
I have a non-powered version that I keep threatening to finish. So I am interested in your flight settings for your control surfaces.

Are your initial control surface settings the ones from the website? (I have attached the guide I downloaded from the website)

Your programming will be very helpful to me as I have the same radio, although I usually have my flaps set to come down when the throttle is pulled rather than pushed. On my powered sailplanes I set my motor up on the trainer switch so it is either full on or off. On the heli version it is really nice since the switch is at the back top position.

I am going to try this plane out as non-powered first, then if I don't like it I can convert it to electric since the fuselage is the same size and shape for both electric and non-electric versions.

Mark
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Old Apr 23, 2012, 04:55 PM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
1,114 Posts
Were you able to find the Robbe 2 servo mounts or did you mount your servos in the wings and use covers?

Marl
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