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Feb 16, 2016, 04:05 AM
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headlessagain's Avatar

Slope maiden


Managed 3 hours of slope flying yesterday at Bratton Camp (next to Westbury White Horse,Wilts)as the conditions were ideal for the slope - average 20 mph northerlies and sunshine
After a quickie woth my trusty Zagi I concluded that lift was more than adequate so it was time to committ the Zulu to flight. Doug my fb did the honours and off she went.
I'd put in a few clicks of up trim but needed to dial this out as she was constantly nosing up as she went out over the slope into wind. After a minute or so I switched to high roll and mid pitch rates and started having some fun with it. I did feel that the dive steepened up a little when pushing the nose down so I reckon I could add a bit of nose weight to move the c of g forward. Maiden was done on the stock recommended c of g.
Overall I'm pleased with the model. It's very aerobatic and with it's thin section should penetrate well in windier conditions. The main problem is getting it to land. I went around several times before eventually bringing her down. It's not a model that I would want to force down as the fuselage and nose is thin
HobbyKing composite Zulu flying wing - maiden flight (5 min 31 sec)

Andy
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Feb 16, 2016, 12:01 PM
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Nice maiden flight Andy. Have you any provision for ballast?
Feb 16, 2016, 12:46 PM
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Thanks. No ballast provision at the moment. I just have 100g of sheet lead sheet cut to the shape of the internal ply plate and bolted in place. I could secure some lead under the wing seat but I think she is more of a lightish wind model which for me is under 25-30 mph. I wouldn't want to come in hot with lots of ballast onboard as I'm not sure how the fuselage would cope. It's quite a bit thinner than my other molded ships. I've a EPP-Modelle Pluto (NCFM mk 1 Bluto copy) and a Zackspeed on the bench for when it's windy which will both have 400g ballast capacity. Shouldn't be an issue for them as my smaller Wisel can happily carry 248g even if only 20 mph winds. It does let it fly in a 50 + mph blow
Andy
Feb 16, 2016, 04:02 PM
Registered User
Hi headlessagain;
Nice footage .. looks like one of those magical sloping days! That footage may well be a 'first' as far as this plane is concerned, too. Glad all went well ..

I noticed the tendency to come out of the roll with its nose pointed very much down .. this is the same with mine. Did you try a dive test? Also just wondering how much aileron deflection you have set on hi-rates to achieve those rolls?

I agree its pretty tricky to slow down for landings, too. I've been wishing for flaps but I think the only engineering answer might be built-in speed brakes (but this is way too much effort compared with 'waffling'-type pre-landing speed-killing manoeuvres, methinks).

My last flight at the field ended up with a disaster! I'm still not entirely sure about what caused it ... it may have been a faulty Tx battery connection or loss of Rx signal (perhaps caused by the carbon fuse/my ad-hoc antenna mounting arrangement). Either way, it seemed to not be responsive to any up elevator or aileron input and she ploughed in at high speed. I've just spent the last couple of weeks attempting to repair it. She's ready for flight again now .. (but pretty ugly). Snapped the nose off at the fuse junction, too.

Just for the record, the wing gets its strength almost entirely from the epoxy/kevlar/carbon skin covering. This covering separated from the foam core in my crash, resulting in floppy wing around the wing saddle. I had to create a series of holes in the skin and inject urethane glue into the holes to rebond it to the core. This seems to have restored it back to its orginal strength/stiffness. Will find out shortly ...

Cheers
Feb 16, 2016, 04:35 PM
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Thanks and yes, it was a perfect afternoon at the slope. Although, at only 5 deg C plus the wind chill, it wasn't exactly warm. Good job I had plenty of layers on and my lined fishing trousers meant that only my feet got cold.
I launched the model with some reflex but had to dial this out as it kept nosing up. Whilst on low elevator rates I did point it's nose down and thought I detected some tucking. It did pull up after a brief hesitation but I then upped the rates to give me some more elevator authority. It might just be me knowing that it's happened to other Zulu pilots.
The inverted seemed fairly neutral but I do prefer a bit of forward stick so a little nose weight wouldn't hurt. Most of the rolls were run on 100% aileron rates and I wonder if the drag of those large control surfaces created drag that was sufficient to kill airspeed enough to drop the nose. I set all my models up with the control linkages on the highest servo arm hole and lowest (only one choice)on the control horn. I then rate down in my DX8 and add expo proportional to the rates.
One advantage of running the powered version would be to apply just enough power to spin the prop slowly. This will create drag and slow the model down. It won't be retro fitted to mine so I'll just have to get used to the glide ratio and bring her in lower than I'd normally do. Crow braking does spoil one.
Re your repairs. Have you considered covering the wing with laminating film? I use 75 micron as it stiffens up foam models and protects them from hanger rash and my landing style. I bought a 100m roll locally for 18 and I expect it will last me for years. You can sometimes obtain end of rolls for peanuts. I've junked the steel wing bolts in favour of nylon ones on the basis that these will shear instead of rip the wing or fuselage in the event of a heavy arrival. It's saved my Flying Fish on a few occasions and that's got a much thicker fuse than the Zulu.
Hope your repairs hold up and the re-maiden goes well.
Andy
Last edited by headlessagain; Feb 17, 2016 at 08:26 AM.
Feb 16, 2016, 06:14 PM
Registered User
Hmm .. re: control surface drag .. you might be right 'bout that(?) .. Sometimes, at lower speeds, it seems like the only reason the plane will roll at all is because of that flap input. I guess what I'm trying to say here is that I get the feeling that the wing area majorly opposes any roll initiated by the aileron input. In yet other words; there doesn't seem to be much assist from angular momentum to keep the roll going (when compared with some of my other slopers). It seems that the expected momentum build-up is instantly squashed by the wing dynamics(??)

Hadn't thought of using the motor to slow it down for landing! (I'm not sure I'm a good enough lander to play around with that, whilst there are other things ta deal with! )

Re:laminating ... sounds like a good idea .. I'll have to snoop around and see if I can get my hands on some lamination materials ..

Re: wing bolts: I couldn't buy any just the right length .. so I ended up making some on my lathe! After the crash however, I noticed that there is actually a hollow rod running thru the wing which supports the entire bolt shaft. (Ie: not just the top and bottom layers of carbon sheet). I think this changes my thinking about hoping the bolts will shear before the wing ... in case of 'overload'. In fact, all of my wing damage was around the saddle. area Even the carbon saddle cracked. The foam/kevlar adjoining the carbon saddle also tore in several place (close to the fuse). This tells me that it still preferred to destroy the wing, rather than shear the nylon bolts I made.

Cheers
Feb 17, 2016, 01:49 AM
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Re use of the motor to slow the model. Practice at height by just adding enough power to spin the prop and see how the model reacts. There shouldn't be any pitch change unlike when using flaps,spoilerons or crow braking. I tend to have my thumb on the throttle channel on powered gliders when coming in as sometimes they need a blip of throttle to steady them through an rotar . Just remember to kill the power just before impact.
Not sure where you are based but laminating film is known as new stuff in the states and there are a number of threads & videos on it's application. On bought mine from a commercial print supplier but could probably have gone to a company who offer print services for some offcuts
An old trick is to partially cut through the wing bolts to create a weak point. The trick is to not to go too far so that normal flight loads don't lead to premature wing separation.
The results of such a separation can be devasting This scratch built model didn't have bolted on wings but instead the glue joint separated as it wasn't up to coping with 600 watts of motor
Funbat Maxi terminal crash (2 min 6 sec)

Andy
Last edited by headlessagain; Feb 17, 2016 at 08:27 AM.
Feb 17, 2016, 02:27 AM
Registered User
Your commentary on that footage almost deserves an academy award for best comedy commentary!
I had a smile on my face all the way through it!
A hidden talent there ... methinks!?!

Cheers
Feb 17, 2016, 03:55 AM
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I was remarkably restrained. Call it English reserve.
I usually utter Flipping Unplanned Crash Kitting or Best Unearth Gorilla Glue, Essential Repairs. Instead I uttered Should Have Installed Thoroughly
The lipo didn't think it was very funny though
Andy
Last edited by headlessagain; Feb 17, 2016 at 04:02 AM.
Feb 17, 2016, 07:42 AM
Registered User

Hobbyking Zulu


eceived my Zulu from the UK site yesterday midday 24 hours later I am ready to test glide at our flat field - but being England it is raining! I must say a big thanks to the guys who have given such good advice on this forum, it is what makes our hobby great. My Zulu is for slope only, it weighs 586 grms ready to go. My c of g is at 85mm back from the LE. and all tx settings are as you guys have recommended. I am generally happy with the quality, it is not up to Euro standards but their mouldies cost 4 to 5 times as much. I paid 98 UK pounds and this included two installed servos with very good quality push rods and connectors. My only gripe is that the wing mounting holes are both about 3-4mm. off centre - it probably will not affect the flying but it looks wrong and is annoying . I was interested in the reference to the DH 108 Swallow and its tendency to porpoise. All three prototypes crashed with the loss of the three pilots - very sad. It is a lovely looking design and one I will model one day. I think the control problems were linked to the Mach no. - we should not have those problems unless we go very extreme DS ing Cheers all
Feb 17, 2016, 08:41 AM
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headlessagain's Avatar
Agreed, it's not up to the high end European stuff or even some stuff now coming out of China.
I bought my kit when HK had their Cyber sale but I don't think I would have paid the full asking price.
I must admit to not doing a glide test. I just got my fb to chuck it off the 225m slope into the abyss. It's a great slope with only one issue. You fly from the main slope edge but below there is a ditch and final lip. Get too slow to the slope edge and you can't see the model. I blame those Iron Age chaps who undertook this bit of DIY
Good luck with your maiden. Hopefully you can video it so mines not the only Zulu slope video on YT
Andy
Feb 17, 2016, 10:47 AM
Registered User
Be interested to hear how it performs with your cg at 85mm Rogeraitch.
Last edited by bladexxl; Feb 17, 2016 at 11:33 AM.
Feb 17, 2016, 10:58 AM
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headlessagain's Avatar
Added 30g of lead at the front and it now balances nearer to Rogeraitch's. By the way Rogeraitch, what electronics are you running and how did you mount? Those nice HK people don't feel it's neccessary to provide any internal ply in the kit version
Andy
Feb 18, 2016, 03:25 AM
Registered User

Zulu


I noticed that rc_ryder and headless were unhappy about the wingtip fixings - my kit had alloy studs fitted to the wingtips and holes drilled in the wings, so perhaps hobbyking have been paying attention to criticism. I was impressed by headless use of a ply keel to strengthen the nose area, however in my kit was an unlabelled piece of blue foam not being used to protect anything so as it is the same size as the nose cone I am shaping it to fit snugly inside the nose with suitable cut outs for the battery/receiver. I hope that this will spread the load of any unplanned arrival. It will not be as sturdy as headless ply reinforcement but my battery does not fit well with the "keel" method. Bladexxl I will certainly let you know how the model performs at my 85mm c of g just as soon as it stops raining. Headless I am using a 6 channel Lemon rx which is so light it will not register on my scales. It has nice long twin aerials, a facility for satellite, a failsafe and a data plug. I get mine from root729.com in Essex - a really good dealer. My battery is a four cell 2100 mah nimh, no switch direct plug via underside hatch, should last all day and not much lead needed. I will try to video a flight - must get my young grand daughter to show me how! Happy sloping!
Feb 18, 2016, 05:41 AM
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headlessagain's Avatar
I did have the 4 loose studs with flanges. The studs are a nice fit in the wing but the carbon wing tips aren't slotted or drilled to take them. Tape works perfectly well on the slope but I think I'll swap the masking tape for black or white electrical tape
I'm running a lighter set up on mine. I'm using two TowerPro metal gear servos, a 2s 450 mAh lipo connected to a Lemon 6 channel DSMX Diversity rx (sounds like the same one as yours but bought mine direct from Lemon) via a Turnigy 3A UBEC with Low Voltage Buzzer set to 6.1volts. The battery and 130g of lead fits one side and the rx (at the front)and UBEC the other side. I just use tape to hold nose cone on. Quicker than fiddling with the screws and more give if I nose in.
Looks like you might get some decent slope conditions over the next few days
http://www.xcweather.co.uk/forecast/wokingham
Andy


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