Kit Davidson

Still waiting for my subscription copy.........

Hi Dan, In my other life I make double bow Windsor chairs www.welshwindsors.com I use steam for this. But beware, think of wood being a bundle of laminated tubes full of residual moisture. The steam is used to heat this moisture and make the polymers more pliable. If my wood is kiln dried, steam bending always fails. The steam does not make the wood wetter, it is just the medium to surround the wood with sufficient heat. Balsa is very dry. Try putting the balsa pieces into hot water. I also use soaking like this for smaller chair pieces. You can also try scoring the balsa on the outside surface with a scalpel. The scores should go with the grain (I have assumed that you are running the grain from fore to aft on your model) if you have not done that, it could be the reason your balsa is cracking. But back to the scoring; don't cut right through but half way. Your balsa will now bend. The scores may be filled with surface filler because they will gape insignificantly as the wood is bent around the frames. You are going to cover the fuselage anyway. I hope this helps.

Hi Tony, The leftward flight took me by surprise too. As soon as I had placed a washer under the left (from aft) arm of the cruciform mount and another under the upper arm to get some downward thrust, my Zulu flew perfectly.

@import url(/CuteEditor_Files/public_forums.css); @import url(/CuteEditor_Files/public_forums.css); Hi Fellas,   I have just posted a review of my Super Tiger Moth build on this site.    I have a query about the undercarriage. I note that Dave Cooper modified his to allow more shock absorption. Mine came out of the box without a central bolt to connect each leg by cross-bracing. There was a suitable short bolt and domed nut left over in one of the bags. I worked out that the cross-bracing had no effect without it, except visually. If I fitted the bolt, the undercarriage seemed very rigid. I flew without it but bounced on landing. I don't know whether to fit the bolt or not. Leaving it out allows the legs to momentarily splay and spring back. You have been flying yours for longer Dave. What do you recommend? Is your modification the definitive answer? @import url(/CuteEditor_Files/public_forums.css);@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);Edited By Tim Mackey - Administrator on 12/06/2011 18:45:47

I have looked all over this forum ......but am I the only subscriber who has a July 2011 copy with a Fournier plan that has sheet 1 printed on both sides of the plan?   I think I am going to need the wing. @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Thanks Joe - I have resorted to experimenting because there are losses. Probably the most valid of these is the masking effect of the large frontal area of the Zulu. If I had more time I could work out the effective area of the 10 inch propeller disc that is not obstructed and can produce clean thrust. My experiments so far show that a 10 x 5 prop is not enough to get my Zulu off the deck. I have not weighed my model and I did use Solartex. However I think I can improve upon an 11 x 5.5 which was adequate. I am going for a larger diameter next. If I crash - I crash. It didn't deter Hanna Reitsch! @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css); At last I had a completely successful test flight with my Zulu. I took the aircraft to Fairbourne on the Mid-Wales Coast yesterday. Its easy to find your own 100 acre expanse of hard sand when the tide is out. There was no wind and I could take-off in any direction. Minnie the Minx took off like a scale model. It looped, rolled and generally disported itself to my almost entire satisfaction. Almost? I wasn't able to move back to half throttle without losing altitude. I am new to electric flight and I probably have not got the power train dovetailed together well enough. This time I was using an 11 x 5.5 propeller. Earlier I had tried a 10 x 5 and there was barely enough power to get airborne. There is still time to experiment and I might try an 11 inch propeller with more pitch now that I am more confident in what is going to happen after rotation.. My motor can produce 243 watts, so on the 50 watts per lb maxim, there should be enough power for a 2.5 lb model. The makers recommend up to a 12 x 6 propeller. I might try that too. Such fun!  I have 40 per cent exponential on everything and I have limited the range of the flying controls. My earlier flights were twitchy, perhaps because of my inexperience but also perhaps because of the close coupled elevator to the C of G. I have coupled 10 per cent rudder to the ailerons. There is no video of the test flight. I am sorry but you already know that my wife and cameras don't mix. Nevertheless, I flew until just before sunset and I have attached this photograph of the beach car park taken just as the Barmouth train crossed the Maddwych Estuary.  Come and fly in Wales!   @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);Edited By Kit Davidson on 02/01/2011 21:10:28

Nice one Bryan. I forgot to mention in my massive missive that I took and accepted the same advice. The ZULU attracted a lot of interest and admiration but the undercarriage business was an unanimous opinion. My undercarriage is now bent well forwards like yours.   The UK tour is over and the World Champions returned battered, bruised and under a substance abuse cloud. What price the Springboks now? I think Jan de Villiers needs a bit of bending too.  @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Yo Joe!  I cannot give advice, only the results of my experience so far. This is what I know about propellers. Relatively:  1. Propellers accelerate a large mass of air to a slow velocity. 2. Gas turbines accelerate a small mass of air to a great velocity. For a given power setting:  3.  The greater the propeller diameter, the greater the mass of air accelerated. 4. The greater the pitch of the propeller, the greater the distance advanced. 5. Smaller pitch propellers accelerate the aircraft quickly to a limited top velocity. 6. Larger pitch propellers accelerate the aircraft more slowly to a higher top velocity.   I am following Lindsay's design recommendation because as a newly qualified pilot with the reactions of a striking tortoise, I had my fingers burnt when I fitted an 11 by 7 propeller to the motor you have now also bought. I have tried twice since then to successfully test fly my Zulu but for reasons too embarrassing to mention, I kept nosing over on take-off and damaging propellers on the asphalt. Nothing daunted I cropped the propeller with scissors and tried again. By now I was suffering from frontal masking as described in my posting of 23 November. With reduced propeller diameter and power my Zulu hardly lifted off the deck and stuffed in on its nose. My wing retaining bolt sheared as designed but the torque transmitted to the wing half- section atop the windscreen broke frame 3 at its thinnest points just below the wing. The repairs are easy but I will have to get a new wing retaining bolt from somewhere before I can fly again. I am so new at this game I do not have enough spares at hand yet.   Other problems I suffer are connected with the battery tray. It has broken free in relatively minor nose-overs and decelerations several times. It cannot restrain the mass of the 3 cell lipo. Similarly the motor has ripped itself away from 1 bulkhead twice as the propeller grounds. I plan to make my battery tray access hatch much bigger so that I can reinforce both areas.     @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css); Thank you Tim for this prompt response. The fuselage is already jammed with stuff for the undercarriage and airbrakes. But I think I have identified the problem. I have copied below a query I have sent to J P Perkins:    I have taken delivery of a new Power Pod from Sussex Model Centre. A 11.1v 3 cell lipo was recommended. The diagram instructions certainly show what appears to be a 3 cell lipo. But a 3 cell lipo 2180mAh battery is far too big to fit into the fairing cavity beneath the ducted fan. A 2 cell 1800mAh is also too big.

I have just received a power pod for my Discus Mk2. It is beautifully made and comes with fixings. The void in the fairing beneath the ducted fan is designed for a the battery and an interlocking ply fixing thingy which attaches the pod at its rear to the fuselage but also acts a shelf for the battery end.   The motor recommended for the pod by the Sussex Model Centre is a  GW/EDF-64D from the Chinese GWS company. It clearly needs a 3 cell lipo @ 11.1 volts (also supplied by Sussex MC) But the battery will not fit in the void even without the plywood fixing thingy. The battery drawn in the Chinese diagram only instructions looks like a 3 cell lipo.   A table on the  the Ducted Fan box,  says the thrust from a 2 cell lipo @ 7.4 volts is 212g (7.48oz). Thrust from a 3 cell lipo is 212g (14.46oz) .    With the mechanism for airbrakes and tow release already in the fuselage, there is no room for a 3 cell lipo in there.   Does any forum member have any experience of this power pod? Should I be using a 2 cell lipo and not the 3 cell supplied by SMC? I think it might be a tight fit but I am not sure that only 7.48 oz of thrust will be enough for take off.    I want to do it this way because I don't yet have the confidence to throw such a beautiful glider off the cliff.  @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

I have completed my second test flight. It was less successful than the first. Most of the failure was my own fault. I relate what went wrong here for the benefit of any other new builders approaching the same stage.   It was fine and sunny this morning with a wind of about 6mph. Conditions were perfect. Minnie the Zulu had new larger wheels, new ailerons and the propeller was biased to the right with 2 washers (1.2mm) under the port cruciform engine mount. I had also biased the propeller downwards by placing one washer underneath the upper cruciform arm. (0.6mm). (My cruciform mount is fitted in the crucifix orientation, not the X ) One of my chums had remarked that the 10 x 5 propeller was largely masked by the large frontal section of the aircraft. I listened but for reasons not entirely known to myself I fitted an 11 x 7 propeller. I still had not fitted a finstrake.   Time for take-off. Minnie shot off and unstuck at less than half throttle, There was no veer to port this time and I was able to control the bank. But I could only liken it to a Sea Harrier leaving the ramp of HMS INVINCIBLE. It was as much supported by thrust as lift from the wing. I could have done some prop-hanging if only I knew how! Relatively small changes in throttle position produced alarming aircraft attitude shifts. I was nervous. I decided that discretion was the better part of something I can't remember and decided to put it down where it was, over a freshly harrowed field. In glide without any thrust effect the Zulu behaved itself. But it came to a sudden stop on landing in soft earth.   I picked up the undamaged aircraft and took it back to change  to a 10 x 5 propeller. When I was connecting up the battery again, I saw that the heavy 3s Lipo had torn the battery tray away from its mountings. The glue joints had not failed but the balsa had sheared along its grain. My battery tray was not hard up behind Frame One as per the plan but had space to move 5mm forward in the deceleration on landing.    I now think my first test flight problems were caused by uncorrected thrust and not an aileron problem. After repairing the battery tray and its mountings, I plan to fit a sensible propeller and remove one of the right motor bias washers. The new 70mm wheels were much better on take-off from the rough surface than the original 50mm wheels. They look right too.   I am learning every day!    @import url(/CuteEditor_Files/public_forums.css);@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

@import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css); @import url(/CuteEditor_Files/public_forums.css); Lindsay,   Good advice! "Modified by Kit Davidson" was not such a good idea after all. The finstrake will help directional stability. It is probably more than the cosmetic touch I thought. I will restore it. Similarly, one of my friends who turned up and saw my Zulu fly, was surprised that there was no bias on the thrust. On full power Minnie seemed to climb at an impressive attitude and I needed to hold it down with by throttling back if I remember. I am now going to try a little right and downward thrust bias as well as new ailerons and bigger wheels.   I have no wing warps and the short couple commented on by  Jet and one of my club members did not present any problems for even me, flying with Welsh green P plates.   I am still reliving my short test flight with pleasure. Dare I say it? The wing incidence from the plan must be spot on!   Kit  @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);Edited By Kit Davidson on 20/11/2010 12:54:07

Well, I have completed my test flight this morning and it was successful - ish! Even with that qualification I was pleased. A couple of taxi tests and it was time to go for it. I heaved back on the elevator and up she went. Minnie the Minx immediately banked to port and flew over the clubhouse and the member's car park. I was the first there this morning - so no bother. I was feverishly applying starboard aileron and correcting the trim with my other hand. The Minx flew for about 5 minutes, always wanting to bank to port and turning to starboard with marked reluctance. She flew comfortably on half throttle. But I had run out of starboard trim on my transmitter.   Time to land. With starboard stick applied, I throttled back and otherwise left the aircraft alone. It came in for a perfect 3 pointer on the grass but stumbled because the grass was a tad long and the wheels were smallish.   I should say that I was always cautious about my ailerons, which I had made on a belt sander.. It was difficult holding the light thin balsa on the big belt without taking the tips of my fingers off. I knew that their profiles were not perfect and rigging the aircraft was difficult. Time for another flight. I lengthened the push/pull rod on the starboard aileron and shortened the same on the port. When I next took off, I crashed. The Minx banked to port again and came down on prop and port wing from about 10 feet. The motor was ripped from its mounting but otherwise there was no other damage. It bounced well!   I have less than half an hours work for the repair and perhaps another couple making and fitting new ailerons. I went straight from the airfield 35 miles to the nearest model shop to buy stock section balsa. It was only my impatience that stopped me from doing that properly during the build.   It flies! But please take my word for it. Unfortunately I enlisted my wife to video the event. With a video camera, she's about as much use as a one-legged man at a bum-kicking contest. Nevertheless for what its worth you can see it here: http://www.youtube.com/watch?v=3EMcx87gNvg&feature=youtube_gdata         @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css); @import url(/CuteEditor_Files/public_forums.css);Edited By Biggles' Elder Brother - Moderator on 19/11/2010 23:00:44

Joe - It wouldn't be fun if it was easy! I am taking pride in coming home from the slope with fewer models in binbags. Take a look at this: http://www.youtube.com/watch?v=MvNd6vmSCcc   Smart!   Kit  @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Joe, I have delayed replying in case Lindsay replied first and because I am having a job remembering. (I am 65, played too much rugby without a helmet and can't even remember what I did yesterday) However I have looked again at the plan and do remember that it was a bit confusing. It says on the plan to cut 16 ribs but you are right there are 18. Also there is another leading edge rib named 1A that one is invited to cut but is not otherwise marked on the plan with its part No. The 17th and 18th ribs are the centre ribs - one to each half wing. Note that these are made from 3mm material. I used balsa.  Its coming back to me! I made the half wings up with 8 x 1.5mm balsa ribs and one x 3mm balsa rib. I then cut the centre 3mm rib to fit the spar. I fitted rib 1A (3mm balsa) afterwards.   The 6mm "rib" that you can see confusingly on the plan lying immediately outboard and at an angle to the centre ribs is the wing support and part of the fuselage.    I didn't worry about an angle to accommodate the dihedral on the centre rib. The spar takes care of the dihedral and the difference between 90 degrees on a properly set rib and the small angle required to offset the centrer rib from normal is less than building tolerance on all the other ribs. Epoxy glue filled any accidental gap.   I cut my ribs in 2 batches of 8 and one batch of 2 (centre ribs) with a scroll saw.    I hope this helps.   Kit     @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);

Watcha Ian!   I did a Google search for the cartoon I wanted. I used the crop tool in Google's free Picasa software. I inserted, copied and pasted in Microsoft Word. I printed the resulting images at varying sizes on special decal paper available in the model shop or by mail order. I did the final editing with scissors.   Inkjet printing needs waterproofing or fuel proofing. I use Artists Fixative but clear matt varnish or similar would do the same.    Kit  @import url(http://www.modelflying.co.uk/CuteEditor_Files/Style/SyntaxHighlighter.css);@import url(/CuteEditor_Files/public_forums.css);