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Feb 18, 2016, 05:51 AM
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Andy, thanks for the wx link - I normally fly at Butser - South Downs just off of the A3 about one hour away. On reflection I think I will use tape to secure the nose , makes sense not to use the bolts.
Roger
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Feb 18, 2016, 06:04 AM
Reap the wild wind
headlessagain's Avatar
Unless you are running a motor up front Now, that would be eventful!
Andy
Feb 20, 2016, 10:39 AM
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headlessagain's Avatar
Had another couple of flights with the Zulu yesterday.The extra 30g of nose weight has brought the c of g forward to around 86mm. It was a steady 20 mph gusting over 25 and I nearly called abort to my brother who was on launch duties. In the end I thought, "what the heck" so off it went. A complete non event as far as drama was concerned although I did need to add some up trim to compensate for the more forward c of g. It cut through the wind and back side turbulant air with ease and both landings were easy. I did need to go around a few times. Still getting use to the glide.
Overall I think it flys better with the more forward c of g. Make no mistake, point it's nose down and it really picks up speed (it's no NCFM Bluto or M60) but it pulls up cleanly with none of the previous nervousness.
Can't wait to try this in lighter conditions when it's clean lines and light weight should mean it will perform well.
No video I'm afraid as my Mobius's battery went flat 30 secs into the flight.
Andy
Last edited by headlessagain; Feb 20, 2016 at 12:01 PM.
Feb 20, 2016, 11:38 AM
Registered User
Andy, just shows that fortune does favour the brave, amazing it flew so well in that wind. I have been considering making provision for ballast but your thread seems to show it would be unnecessary. With the new forward c.of.g that you have it may not perform so well in light airs - no doubt we shall both find out - still not flown my Zulu but Tues/Wed could be good. I have sprayed the underside white with black wing tips and centre section to improve visibility.
Roger
Feb 20, 2016, 12:00 PM
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headlessagain's Avatar
I did add some black and red stripes underneath but I'll also add some white as well.
I'm sure it will cope in higher winds as penetration wasn't a problem. It could be flown well behind the slope and and still be flown back over for a fly around. That's not something my Zagi and Spectre like to do unless you keep the speed up. The Zulu flew much more like a conventional glider and remained very stable at all times.
Hope your maiden goes well. Video if you can.
Andy
Feb 20, 2016, 05:14 PM
Registered User
Quote:
Originally Posted by headlessagain
Quote:
Originally Posted by rogeraitch
On reflection I think I will use tape to secure the nose , makes sense not to use the bolts.
Roger
Unless you are running a motor up front Now, that would be eventful! Andy
Interesting...
After reading the above, I abandoned my idea of using tape only to secure the motorised nose on my repaired Zulu.
However, after reinstalling the nose bolts (which should really be nylon), I'm having second thoughts again.
See, I noticed the damage following my nose-down-at-high-speed crash was mainly to the carbon fuse immediately aft of the nose bolts (ie: not in front of them). This happened because the force on the nose was directed towards the tail.
I'm thinking that if the nose was secured only by tape, then the damage to the fuse aft of the nose bolts wouldn't have happened. (The nose would simply split down the seam .. but this is relatively easy to repair, compared with restoring the carbon fuse aft of the bolts).

I'm not sure, but I reckon it'd take a lot more thrust than the motor/prop combination can achieve, to break a tape seal coupliing the nose to the fuse(?) ... and I think the bolts should definitely not be of (the supplied) steel kind.

Just food for thought, I guess ...
Feb 20, 2016, 05:21 PM
Registered User
Quote:
Originally Posted by rogeraitch
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 .
Mine has the same flaw.
The issue I found here, is that one of the control surfaces makes contact with the fuse before it reaches its maximum deflection. I found I had to grind some of the inboard end of the flap surface away, when I was going for maximum deflection, (down elevator/aileron), in order to provide the necessary clearance.
This opens up a gap between the wing and the end of the flap .. which sort of spoils the look (and increases drag).

Cheers
Feb 21, 2016, 02:00 AM
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headlessagain's Avatar
I'm sure a couple of wraps of electrical tape would hold up to the tug of a 100-200 watt motor. However, the nose cone is prevented from coming too far back by a flange so even if taped on could still potentially transfer the impact forces back through the rest of the fuselage.
I went for nylon wing bolts and added a ply plate under the wing saddle as well as the vertical ply bulkhead extending to the tip of the nose cone. I still think that the fuse needs some bracing under the wing area as I could feel the fuse flexing just holding onto it as I steadied it for a solo hand launch. I'll see if I can introduce a ply dics through the bottom hatch. Once in I should be able to rotate it in place. I even considered using the expanding foam to fill the fuselage aft of the bottom hatch but decided that the extra weight and risk of distortion wasn't worth the additional strength that this would bring.
Andy
Feb 24, 2016, 01:24 PM
Registered User
Went to Butser slope today (South England near Petersfield) wind was NE 5 mph as forecast - I nearly didn't go - in fact I was alone - so sorry Headless - no video. After an hour the wind got up just a little, not enough to hand launch from the slope but I hurled my discus launched lightweight up about 100 feet and at that height it stayed up and I had a good flight. after another hour the wind edged up to 8 mph so I gave the Zulu a fast launch. No trim problems, it went straight out of my hand and started to climb! So it will fly well at low wind speeds - keeps its energy well - this is a very slippery wing.
loops and rolls were good and then........the dreaded dive test! I did three to confirm results and all were the same - gently recovers from the dive without control imput. I did three landings in total and found that steep turns from side to side levelling close to the ground suit my flying and work for me. So I am very happy with this glider - I agree it needs some "beefing up". C of G for me will stay at 85mm back from the LE. Does anyone know why the price in UK has doubled in the last week?
Roger
Feb 24, 2016, 02:01 PM
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headlessagain's Avatar
Good to read that the maiden went well and that it fly's in light conditions.
For solo video recording I just velcro my Mobius A lens camera onto an EPP wedge glued on my baseball hat peak. The picture shows a similar set up to mine. I also shoot static video footage using a Kodak Playful mounted on a selfie stick with a solar light spike at it's base
The price hike is just HK putting the price back up to the normal price. Yeah, I don't think it's worth the full asking price either but at the 85 I paid I couldn't resist
Feb 24, 2016, 03:08 PM
Registered User
I've also been out for a few more sloping sessions in a stiff seabreeze with my rebuilt Zulu. Its interesting. This plane has a lot of lessons in store for me. I've only ever flown one other wing which was a thrown together home built conglomeration (which is also a lot of fun in lighter winds). The Zulu is a different beastie from this .. altogether.

I think I've discovered what caused my original crash. I'm pretty sure the 124g 3S 1500mah battery I'm using, (for powering the motor), moved forwards in mid flight following a series of aerobatic manoeuvres. This would have shifted the CoG forwards by maybe more than 10mm, which then caused the terminal irrecoverable dive. See, also on the first flight, following the rebuild, I noticed that the battery went into the nose a little more than it should have. I just thought it was me, so I went ahead and launched anyway. Holy smokes! I was lucky to scramble out of that one! I now know what happens with a too forward CoG on a wing!

As a result of these two past experiences, I think this plane is extremely sensitive to CoG changes .. like pls/minus a couple of mm! If its not just right, it has a tendency to 'lock into' a stable dive position and even the large control surfaces, (and largish throws), are incapable of pulling it up. I think this apparent 'lock-in' (stable) position might also be a function of air speed over the wing, also(?)

I'm wondering whether or not other folk might have encountered these characteristics yet .. or is it just my lousy engineering (in restraining the battery) or maybe, just lousy flying skills?
(The condition seems to be consistently brought on by steep dives).

Cheers
Feb 24, 2016, 04:16 PM
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headlessagain's Avatar
A lot of plank style wings are very pitch sensitive to c of g position whereas a swept wing will fly ok within a wider range. There's is still a sweet spot but it's not as critical. Now, the Zulu is a somewhere between the two with it's swept leading edge and straight trailing edge but probably closer to a plank than say, a Zagi.
I'm perfectly happy with mine at 85mm especially as I know it will fly well in 25+ mph and Roger is happy with it in light lift. It wouldn't be the first time that HK have stated the incorrect c of g
It a bit of a concern that your lipo pack is shifting but at least it wasn't rearwards. I never like trying to fly a windblown paper bag I usually find that velcro is all my packs ever need and my models range from 3D models and 100 mph ones
Andy
Feb 24, 2016, 05:47 PM
Registered User
Hmm .. I think I really need to redesign my nose arrangement. I'm using (mostly) the battery weight to maintain the correct CoG. I did this to keep the whole thing on the lighter side of the weight scale .. rather than having two separate weights .. ie: one for balance and the other as ballast.

At the moment, I'm loading the battery from the belly hatch and sliding it forward into the nose until it comes up against a foam block I installed just behind the motor. (The foam block moved .. causing my crash, I think). If I try and use velco on the battery, its almost impossible to get it out again without removing the entire nose cone.
I've had to stick my antenna out of a hole in fuselage, just aft of the belly hatch, because there's no room for the Rx in the kevlar nose cone. (The battery and the the esc are in there ..).
Feb 25, 2016, 02:56 AM
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headlessagain's Avatar
HK seem happy to leave the how of the electronics installation up to the punter. There is no suggestion of how to mount any of the gear apart from the RX being sited in the radio friendly kevlar nose cone. If it hadn't been for some ideas over on a german thread I might have had a bit more head scratching before tackling my build.
There is a video by Christian Repey of him flying his powered Zulu so you could ask him to post pictures of his set up here
Zulu Hobbyking first flight short version (3 min 55 sec)

If you like the style of plant wings then have a look here
http://www.wing-tips.at/Portraet/Modelle/modelle.htm
Andy
Last edited by headlessagain; Feb 25, 2016 at 03:14 AM.
Feb 27, 2016, 02:20 AM
Registered User
Hi Andy!

HK's Zulu was on sale again and after reading this thread I couldn't resist to buy one

Now I will finish "the build" of this wing based on your recommendations:

- nylon screws to fix the wing
- thicker wing saddle - layer of glass cloth
- ply wood plate and disc to install the equipment
- lead for the CG which seem to be around 85mm from the leading edge (!?)

I guess that's it!?

www.wing-tips.at is an excellent recommendation - I also own a Zorro Light and a Chinook!

Juergen


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