Simon Chaddock

Futura57 My Skyray is not trying for speed but for the more difficult target of the "appearance" of a scale speed. For a human on the ground it is the perceived angular change for a plane to travel is length. The further away and smaller it is the slower it appears. Our models are small to start with so they have to fly slowly even when they are close by! For a given airframe its flying speed is directly proportional to its weight. Slower means lighter. However the wind is not scale so it does make such planes "calm weather only" flyers.

Truly calm this morning so I took the opportunity to maiden the much rebuilt Depron EDF Douglas Skyray. 36" span but with loads of wing area coupled with a meagre 20 oz (554g) all up giving it a glider type wing loading Slow and docile but quite an eventful flight nevertheless. https://www.youtube.com/watch?v=fNv_YloJanY&t=16s It does not use a commercial EDF but a Emax 2205 drone motor driving a 3x4.5 3 blade prop within a 3d printed mounting.. The Skyray uses a 1300mAh 4s LiPo. Another to add to my collection of "silly" planes 😉

JamieM You do need to be careful with any charger you choose. The Apprentice STOL uses a particular small LiPo battery that must be charged by a smart charger. It only has one lead. The "smart" in the charger automatically takes care of charging the LIPo safely. A more conventional and bigger LiPo has two set of leads. A main lead that is used to both power the plane and for charging. There is in addition a "balance" lead that has connections to each cell in the battery. For charging both leads are plugged into the charger so it can charge and at the same time monitor how the charge is going in each cell and adjust the individual cell charge so all the cells are brought up to exactly the same full level then charging stops automatically. A LiPo must never be over charged. On this basis I would recommend you get your Apprentice STOL flying using the as provided charger as it is rather specialised to the application. Nothing wrong with buying more identical batteries to use to get more flying time. However if and when you want to move onto larger planes the batteries and the charger will be different and more "universal" in their application. The important thing is to ask for advice from a site like this on your next plane and the charger and batteries it might use. At the same time you will be advised on how applicable it might be for the plane after that!

Yes indeed If the X-3 was a delta I would have less concern about the ability to keep the nose high during the flare, deltas do it it easily in combination with the ground effect, but the X-3 is very different. I would expect it will not have the elevator authority or the thrust to weight to be able to hold an exaggerated AoA. With a full length nose I suspect the actual landing will have to be a compromise between the speed needed to keep the nose even slightly above horizontal and the risk of damage to nose from the resulting long(ish) grass ground run.

Moving on I have started the fuselage tail section. It has a rather rapidly changing shape so it has been built as a half shell over the plan. Tapered, twisted and formed planks so rather slow going. Once lifted the other side of the formers are added and the planking has to start all over again. The one piece tail plane (less elevators) is slotted through the tail. The fin and fixed rudder is slotted in vertically to rest on the tail plane. It is then they are glued into position. The tail temporarily taped onto the centre fuselage to see what it looks like Note the LW-PLA printed tail cone and the hard balsa reinforcing embedded into the tail plane. The buried elevator servo and elevators next. The ridiculously long (delicate?) nose and the side area it creates suggest that for the initial flights it would be sensible to use a "stub" nose that terminates just ahead of the cockpit. In fact truncated like this the proportions of the X-3 start to look almost normal apart that tiny area wing!

FB3 Just a word of caution, The gyro reacts fast (much faster than a human can) but has limited authority. So do not expect the gyro to completely stop a really big disturbance. In such circumstances the gyro will hopefully slow things down enough to give the human time to put in an appropriate more powerful powerful correction vvvvvvvvvvvvvvvvvvvvvvccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc nnnnnnnnnnnnnnnnnnnnnnbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb. I use Lemon gyro receivers on my really light weight slow flying foam planes. The result maxes a twitchy plane quite relaxing. It also allows but only up to a point for such to fly in what might otherwise be considered unsuitable conditions.

Hoochykins You asked if the motor you had chosen would be over powering the Easy Pidgeon? It is a huge 450Watt motor so the answer is a most a definite yes. Particularly after the comment made by JD 8 that "120Watts was plenty". You may decide you need its 177g weight for balance but honestly you would do better with a much smaller lighter motor and then add some lead! At least you can remove lead if you find the correct balance can be achieved by relocating other components.

Hoochykins Just an observationt but "throttle on a switch" is rather a brushed motor/NiMH feature. The power output was so low and the inertia of the brushed motor was such that instant switching on was not a significant problem however switch on a Brushless/LiPo to instant full power can be. The instant torque generated can effect the plane unless the speed controller can be programmed to allow it. A plane speed controller is designed to give an infinitely variable throttle. It is a pity not to use such a feature. I have owned designed hand launched powered gliders that really only use full power to "show off" what it can do. According to the manual the 1.7 m Easy Pigeon used a 540 (36mm dia) motor driving a 7x4.5 prop powered by a 5 cell (6V) 1500 or 1700 mAh NiMH pack. From my own experience with my first Brushless/LiPo conversion this tiny Emax 2812 40g motor (its just 28mm dia and with rear leads) in its 1500Kv version will happily drive a 7x6 on a 3s 1500 mAh LiPo producing more thrust than the 540 ever did. The 1200kV version will happily drive a 10" prop using similar amps but generating a bit more thrust. By far the bigger issue is not obtaining the necessary thrust but the huge reduction in weight that results from Brushless/LiPo . The motor is only 1/3 the weight and even a 2s 1500 mAh (8V) LiPo is about half the weight of the same 1500 mAh 6V NIMH. You may have to consider carefully the size and position of the LiPo needs to be placed to retain the correct centre of gravity. Also don't forget a LiPo is a "high energy" battery and absolutely must use a dedicated LiPo charger for safety. As Frank D points out don't rush at it There is a lot to learn about how to make best use of the "modern" technology to satisfy you own interests. I never intended to build a "collection" but of course I did! No kits all own design and build.

Dave That is a spectacular and almost beautiful wing in line with "Wood is good". Except and perhaps to be a bit controversial it does rely pretty heavily on a non wood material for its strength! My own vision is to "Use a material best suited to the application and then use just enough of it to meet the duty required". It has to be a "vision" as its almost impossible to achieve without resources I do not have access to or can afford. About the best I can do is follow the adage "Try, Break, Improve, Repeat"!

When I built my small RC Pup it was this picture that demonstrated just how frighteningly delicate the full size was bearing in mind the Le Rhone rotary accounted for 34% of the plane's empty weight.

Just to be sure I load tested the wing using my crude support it by the wing tips to load the wing root the equivalent to pulling 4g. With the fight battery resting on the fuselage and with the EDF and ESC already built in that accounts for all the heavy bits with no noticeable wing bend . In total it weighed 356g The nose and tail section will all Depron structures and will add about 60g. This test seems to show the wing will be adequately strong it proves to be able to fly! The centre fuselage is now fully planked. I will leave the wing uninstalled and move onto the tail section. This will of course include the elevator servo. Its wire will have to be run through the now fully planked centre section.😟 Just as well I built in a servo plug tube that runs through all the formers to the battery compartment.

Nice picture! I did not know the cockpit entry was from the underside. What intrigued me more was what were the two planes in the distance? Looks like a F102. The white one the Bell X5?

I could easily increase the wing area but point of this build is to try and emulate what looked absolutely ridiculous 1952. I suspect "fuselage lift" will become significant but I won't be in any way disappointed if it simply cannot be made to fly. However if that proves to be the case it might be interesting to see how much more area is required before it will.

The middle 103mm of the wing chord fed through the fuselage. It is full span but looks plainly ridiculous on such a large structure.r The swept wing spar is a veneer/Depron/veneer structure with carbon tow glued glued over the centre join. One advantage of the very modest span is even the scale thin wing should be adequately strong enough. I can only hope when the full chord if the wing is built up it will look a bit more realistic but I doubt it!

Wow! Are you really planning that rivet detail? As I was using high revving Scalextric 12V motors they had to be geared. They already had small pinions fitted so I took a guess at the overall ratio to turn the 8 inch scale props. I was fortunate that my Dad was a true model engineer so he cut me a pair from a high strength aluminium and turned up the appropriate hubs, Steel shaft inner with ally tube outer. The steel inner ran in a brass bearing at the motor mount, The outer ran in a split plastic bearing right behind the props. The result was quite a neat contra prop setup. Of course only a tiny power output by RC standards, about 50W in total, but it did mean I could carve my own "inserted blade" props from medium hard balsa. The only disadvantage was that the high revving straight cut gears coupled with a "sounding box" hollow wood airframe meant it sounded like a turbo prop in the air. In principle at least a "beefed up" version could create contra props using unmodified brushless motors.

A very impressive build. I note you have included the fabric covered rudder. The only such material used on the whole plane! It is remarkable that the modest Martin Baker organisation managed to produce such a remarkable and practical fighter. Given it was only ever experimental and flown by test pilots it does seem a pity that it was not kept but ended it days as a target on a firing range. What prop will it have? It does look much better with scale diameter three bladers. 😉 Indoor, electric and control line. 24" span it weighs 4.5 oz (128g). Built 55 years ago. I still have it but now firmly retired.

Started to think about the wing structure. The original used a very thin supersonic section with a sharp leading edge. As will need all the aerodynamic lift I can get my intention is to retain a scale "thin" wing, 12mm thick at the root but use a more conventional flat bottom section with a radiused leading edge to hopefully to be able maintain control at larger angles of attack. As a belly lander it really will need to land nose high. The middle 103mm of the wing chord which includes the spar will have to be fed in between formers 4 & 5. Once the wing is secured in position the leading and trailing edges can then be "made up" to the full 230 mm root chord. As slow speed control will be important I may have to increase the area of the elevator and ailerons Undecided whether a rudder is worth the extra servo weight. I did say the X3 was likely to take some time. 😉

I would certainly set about reducing the charge to "storage". I fear if the inactive period with a high charge level has caused any reduction in capacity the damage is already done. However if you reduce them to a true storage any damage will stop. When you do want to use them at least all the cells will start from a known level so you will get a good idea from the charger how many mAh has been put it. "Storage" normally represents between 35% to 40% charge so you should see a full charge put in a good 60%. Much less than that and you have to recognise the flight duration could be compromised. In any case after such a long period of non use it would be wise to only gradually extend the flight times monitoring carefully the state of the cells after each flight. I hope this helps..

After many hours the planking on the centre section is nearly complete. The only bits left open are where the one piece wing will slide through. At this point the slim chance that this project succeeding is brought in to focus by sitting it on the plan for the wings. There is about 2' to be added on the rear and about the same on the front No matter how light the complete fuselage might be that is a seriously small wing area, let alone achieve a hand launch! I suppose it is a case of "Nil desperandum" and carry on regardless.

toto The important issue is how long the batteries have been sitting above say 50% charge. "Storage" means what it says both for safety (less energy in the battery) and getting the maximum life out of the cells. A charger will/should "balance" discharge so all cells are brought to the same "storage" voltage likely to within 0.01V. It is actually using a LiPo at a high discharge rate that shortens its life the most but dropping the cells to an accurate storage level, particularly if the "no use" period is unknown costs nothing but time but as stated a fully charged big capacity 6s may be best discharged first. . If the battery is at say 40% from use it will not take a charger long to bring all the cells to the storage level. I know if I have worked a battery hard my charger set on "storage" automatically brings the cells up to the storage voltage.

PDB The planks are all 3mm Depron as are the formers. Over the flatter areas each plank is a generous 28 mm wide. At the more complex shapes each plank will be no more than half that width They will also be shaped, the edges bevelled and the plank hand formed twisted as required so it lies as a good fit in its natural state. That way the loads to make it fit "snugly" are within holding power of the pins. When the skin is complete and after a light sand the pin holes are small enough to be completely filled by a light "wash" coat of thinned lightweight filler. The X3 was white overall so it will only take a light coat of white paint over the white Depron. Resulting visibility as an RC plane? Terrible! Unless over head or very low against the greenery!

Planking underway, the simpler almost flat areas first primarily to give the formers some rigidity. You need a lot of pins! This the underside. The really complex bits are when there are rapid changes of shape leading to the inlets and exhausts. It requires individually shape and twisted planks to get a good join to its neighbour. Overall it is rather a time consuming process as you can only do so many planks and then you have to let the glue hardenm

The EDF & Inlet formers made and fitted. They are the easy ones! After good few hours over a period of two days the full set of fuselage centre section formers. Delicate but can be safely handled. One advantage of working in Depron is each former can be easily "adjusted" by sanding or adding pieces so the profile of each former follows smoothly on from it neighbour on either side. It need plenty of "eyeball" and imagination to ensure the ultimate shape will come out close to that of the plastic kit Now to start planking but keeping in mind the how and when the wing and the "permanent" electrics need to be installed. The battery hatch will be cut out once the battery position is determined and that won't be able to happen for quite some time.

Most folding props are designed to be used in glider types that have a relatively small nose profile. . You would have to make sure the blade folding hinge line was outside the diameter of the spinner. Then as J D 8 points out how well will a folding prop cope with the Spitfires nose profile.

Jonathan Electric motors are fully reversible so electric props tend to made in CW and CCW. Just make sure the rotation of the prop matches your side thrust.