Peter Jenkins

With the wing firmly bolted in place, it was time to check tail and wing incidences. The engine is set at 0 deg to datum so it was a matter to levelling the fuselage top and then measuring wing incidence. As luck would have it, the wing came in at 0 deg! How lucky was that! With the model turned right way up and the fuselage packed up to set the wing at 0 deg, I then adjusted the tailplane mount to get that to 0 deg and also to confirm that with the fin jammed between the fuselage and rudder post, that the tailplane was still at right angles to it. The final check was to adjust the distance between the wing tip and the tailplane/elevator join so that the tailplane was centred in that way and then to mark this position on the tailplane and fuselage. Incidentally, you can now see the extent of the fibre glass bandaging on the wing as well as the ply reinforcement on the outside of the fuselage.

Posted by john stones 1 on 24/01/2019 22:06:41: Silence is deafening on this I see, had it been an M/R we would be on page 20 by now, BMFA would be being lambasted for not distancing us from "them". +1

The next job was one I had been dreading! Drilling the hole for the wing dowel in the bulkhead. After careful measurement – several times – I eventually was happy with the position and applied the drill. The large wing opening and difference in height between the front and rear of the wing bay allowed me to put the electric drill into the gap and drill at right angles. The wing then slid into place. Phew! I could now use my Dead Centre to mark through the wing bolt brackets from above the wing and then drilled the bolt holes. Thankfully, I got it right – well, almost! After a little relieving of the holes, the bolts went in. The next job was to tighten up the wing bolts and check for fit. – before final easing and being able to tighten fully the bolts.

Nigel R, thank you for your suggestion. However, what the photo doesn't show is that the elevator is cut out of fairly stiff balsa. On a twist test, appropriate to the amount of aerodynamic force to be expected, it performed as well as a wire saddle. Added to which, I am happy to accept that Mick Reeves knows a thing or two about what constitutes adequate strength. This will be used for precision aerobatics and not 3D so I am quite content with the strength of the elevator. I am using Dubro large horns that have good surface area for both the horn and the back plate so, again, I am confident that my solution will be perfectly adequate. You are free to disagree of course!

That will concentrate a few minds!

It was now appropriate to check the wing fuselage join and the wing/tailplane incidences. First, I had to glue on the reinforcing ply pieces on the rear undersurface of the wing for the wing bolts. Having checked that I could still access the retaining nuts for the wing bolt brackets, I glued the fuselage bottom in place. As you will see, this left the necessary access to which I’ve just referred. I then lined up the wing bolt brackets, marked the bolt holes and drilled them. An earlier purchase, a set of locking forceps, now came into their own to hold the nylock nuts in place while I screwed the bolts home. Note the mark for fuselage centre line which I will use to line up with wing centre line.

Tailplane and elevator showing hinge point placement. Note that the elevator is a one piece item. This meant that I had to glue the tailplane in place with the elevator hinged. That triggered the thought that would need to cover the tailplane and elevator and at least the rear of the fuselage adjacent to the tailplane before gluing them together to avoid an awkward covering job.

I finally found my David razor plane coming into its own for shaping the fuselage top decking! Only had it for 10 years! Final shaping would have to wait until I had the tailplane ready to mount. And so onto the tailplane. Construction is quite straightforward. Just glue the 3 bits that make it together and round off the LE and tips. I had read a report on a Gangster build that said the elevator and rudder had been increased in size. The existing elevator and rudder did look a little on the small size so I cut some slightly larger surfaces from my stock of balsa. The David plane was a great help in shaping both the elevator and rudder in short order. I finished off with my trusty Perma Grit sander on the medium setting and finished off with 600 wet and dry. The ailerons called for Robart pin hinges so I thought I’d use them all round. The Robart pin hinge drill jig made drilling the holes in the centre of the fixed and moving surfaces very easy. I did that before chamfering the edges – another job made easy with the David plane. The fin and rudder mirror the tailplane and elevator for construction so I won’t bother telling you about them.

Signed but I think it should be restricted to those who are under financial stress. Many 75+ will have sufficient income not to need this help. Why give public money to those who don't need it?

Started building flying models in 1963 - KK Hurricane! Of course, it didn't fly! Then bought Peter Chinn's all about Model Aircraft and found out that when you dope tissue you stick in on first! That explains the wrinkly Hurricane! Then Mercury Magpie (flew well). Various other free plans from Model Aircraft Mag. Joined the Wings Club - still got the enamel badge somewhere. Big step was buying a Mills 75 in 1965 (still got it) but sadly it must have been a Friday afternoon job as the compression stop had been put in one turn too early! It would run, just, but the model it was in, Veron Provost control liner, never moved! Then a Wenmac trainer - ready to fly plastic C/L job. The Wenmac Hotshot was a great engine. Easy starter on the front really worked and the power was amazing! Took many years to get to fly more than 3/4 of a circuit by which stage all the plastic pins holding the fuselage in alignment had broken off. Then Phantom Mite - good. Then Early Bird combat wing with PAW 249! Amazing setup. Learned to fly aerobatics and the EB was tough! Then into building MacGregor radios - never worked. Bought RCS single channel with Elmic Compact escapement in a slope soarer (daft as I couldn't reach a slope so just towed it up). OK but eventually totalled. Then buiilt a Quantum 6 proportional Tx, Rx and 1 servo amp (they PCB was so small I gave up and bought the other 3). Build own design trainer with OS 30 RC but it never flew as the range on the Quantum 6 was about 20 yrds despite taking it in to Remcon twice - It's all working fine mate! Bought a Futaba M series - beautiful - still got it but never used it. Stopped when I went to university and found a full size gliding club there. Then after getting a Silver C took a PPL conversion course and keeping that PPL going precluded model aircraft expenditure. Brief return to C/L to give my 2 sons a feel for it - no joy - they were more interested in rugby, hockey and cricket. Eventually, returned to hobby in 2002 and into R/C with Futaba - wow what a change from the old days. Never really had the time to take flying seriously till I retired. Got my B went into competing in aerobatics (F3A) and have learned more since doing that than in my entire modelling career up till then - and still learning. Getting back to building now rather than just buying ARTFs but not for the 2 mtr aerobats! One good thing with getting a B and going into aerobatics is that it has reduced my crashery considerably. Does mean the hangar is a bit full. There has only been one 2 mtr totalled when the brain fogged - so far!

Once the basic fuselage was dry, I had to turn it upright and then I added the remaining 3 formers and drew the fuselage together to join on a stern post to which the fin gets glued. This was a slightly tricky job as the wood in the 2 fuselage sides was of different stiffness so required additional clamps to hold everything so that it was not just square but also symmetric in shape. Once the glue had dried, it was time to fit the sloping fuselage side. This was when the last former proved to have an error in shape. This meant having to build it up with scrap balsa in order to make good the error. Gangster 21 and 22 At this point in proceedings, I re-read the instructions regarding the CG position. It turned out that the prototype Gangster, while being a delight to fly, would not stall or spin. MR put about 4 ozs of lead in the tail and that cured the problem. The original CG of 3.5 in back from the LE was amended to 4.5 to 5 in aft. As I was going to be using a 2 stroke as opposed to the prototypes 4 stroke, albeit with a pipe, I reckoned that having the rudder and elevator servos mounted in the tail would be a better way of getting weight aft. So, I made 2 cut outs and reinforced these with ply for the rudder and elevator servos. You can see the addition of scrap balsa to allow the second sloping fuselage side to be fitted here. Gangster 25 Having sanded the two sloping sides flush with the formers, I was able to glue on the fuselage top, which was a fairly thick piece of balsa. Gangster 26 and 27

That's what post start engine/motor checks are so valuable. For an IC it is obvious when the engine is running backwards because the exhaust goes the wrong way. Holding an electric and powering up is good and you can also check your failsafe is working correctly, You do check your failsafe before every flying session for every model you intend to fly don't you? It is a requirement of the ANO that the pilot in command must be satisfied that the flight can be completed safely before taking off. However, we've all been there. The important thing is to learn from experience and don't let it catch you out again.

Jonathan, a couple of things I forgot to mention in my earlier post, First, always check how much the charger puts back into your pack. That is the only reliable way of determining how much you took out of it. I usually find that while my LiPo checker says 14% remaining, I actually only get around 3,300 mah into a 5000 mah capacity pack. That way, you will be able to "calibrate" what your remaining voltage is telling you and also what your LiPo checker actually means when it says, in my case, 14% remaining. Clearly there is just over 30% remaining. Second, check the internal resistance of new packs. Keep checking them every time you charge. With a parallel charge for 2 packs, I see readings from around 7 milli ohms up to 30 milli ohms. I find that it is not worth using the pack for serious flying if the IR goes above around 30 milli ohms. If you are charging a single pack, then double those figures since the resistance of two 10 m ohm resistors in parallel is 5 m ohm. With 3 or more then the solution is in the equation 1/R = !/R1 + 1/R2 + 1/R3 etc.

I agree that parallel charging is the way to go. I fly with 2 x 5S packs in series to give 10S but charge them in parallel and that takes an hour or less. I normally set the charger to stop at 95% capacity to maximise life and do not charge at more than 1C. Remember for parallel charging you should set 2C as the charging current as it halves to fill the packs. If the packs are not at exactly the same voltage the stabilise very quickly once you have connected them. Connect with the main leads first and then the balance leads. I find that the percentage capacity is a bit of a guess as with my LiPo checker it reads 14% with anything between 3.65 and 3.75 v/cell. I try not to go lower than 3.7 v/cell. I would trust v/cell more than percentage remaining by the way. On this regime, my oldest pack is sitting at 80 cycles and is only slightly puffed. There are a bunch at around 50 cycles that are not puffed at all but are a different make. A LiPo is dead if you drop below 3 v/cell and your charger probably won't be interested if it sees that voltage. My charger puts the cells at 3.85 v/cell on storage mode. However, I don't think leaving them at 3.7 v/cell causes a problem. I rarely leave batteries fully charged for more than a day. I charge the night before. I have 2 high capacity chargers and can charge 8 10S packs in 2 hours splitting them into 2 x 5S packs and parallel charging them. Occasionally, I charge each pack separately to make sure that the cell balancing is on a per pack basis as opposed to 2 packs as for parallel charging.