Danny Fenton Posted October 3, 2016 Share Posted October 3, 2016 Yep that one looks better suited, you are still at the high end of the KV and will end up with a smaller faster spinning prop. Many would suggest this route however, I just like slow big quiet props, but with it does bring additional torque Cheers Danny Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 3, 2016 Author Share Posted October 3, 2016 Thanks Danny. It looks like I'm safe to stick with the one I have then. What a brilliant forum this is. Cheers John Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 3, 2016 Author Share Posted October 3, 2016 H all, After that diversion, back to some building. Next the wing. There is no doubt that this is where the major part of the work lies. The wing is in 3 panels, there are 4 split flaps, ailerons, all with internal linkages plus retracts. So quite a lot to do. The wing has a very thick section (about 18% I think), it must have been the thickest wing of any WW2 fighter. Anyway, it means that we will end up with a very strong & stiff wing with lots of lift. I'm sure that if you wanted to simplify the build the flaps could be omitted , but , "Hey we're making a scale model". The basic structure is quite straightforward. All the parts are very accurately drawn & the wing ribs include jigging tabs so a straight , true wing is guaranteed. If a part does not fit then your'e doing something wrong. The ailerons are hinged on a wire that passes from root to tip & is supported I a brass tube bearing at each end. Having the basic fuselage to hand together with the wing means that the wing fixing can be sorted out now. No problems so far then. Cheers John Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 6, 2016 Author Share Posted October 6, 2016 Hi all, The flaps are simple enough. Just cut from .8mm ply. Ribs are from the same stuff cyanoed in place. The hinges are Robart pin type hinges with pockets to fit the hinges to the wing. This means that the hinges can be detachable, at least for now. I was hoping to retain this ability on the finished wing but because there is no access to the flap clevises from below this will not be possible. For now all that can be done is to ensure that each flap fits the wing & opens /closes fully. Linkages will come later after the wing panels are joined. That's another story. Will have a look at the retracts next time. Cheers John Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 9, 2016 Author Share Posted October 9, 2016 Hi all, Right then, let's have a look at the retracts. Let me say straight away that this is a first for me. Not done retracts before. Still the thought of a Hurricane flying around with the U/C down was a big NO. The full size U/C does not look exactly simple so there was a good deal of head scratching & it was very much a case of making haste slowly. Having seen many models where the under carriage either retracts into the wrong place or ends up sticking out a bit I knew that there would be pitfalls. One of the reasons for building the BT design is having the confidence that he would have it sorted. Anyway, the first thing is to understand the geometry. If you Google; "how to install retractable landing gear" you will find a very good article that explains , very clearly, all about Pintle Angles. The plan does not show any particular type of retracts but shows a typical position for the bearers. You are told that if the angles on the plan are followed than the wheels will be correct when up & down. Next time I'll try to show 'how I done it'. Cheers John. Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 11, 2016 Author Share Posted October 11, 2016 Hi all, For simplicity I decided from the start to use electric retracts. The LMS showed me some very nice units at not very nice prices. In the end I bought some from Whites for a very reasonable £17 each that I had seen at a show. They seem OK , time will tell if they stand up to the racket. I also acquired, from a swap meet, a pair of sprung oleo legs. These came as part of a pair of twist & turn Unitract pneumatic units. 5mm wire joiner was also needed to link the retracts to the Oleos. I wanted a wire leg with a coil Spring & eventually found a pair of Eflight legs. For the time being, however, I used a straight leg from B&Q mild steel in order to check the alignment. Mounts for the retracts were glued up from hard wood bearers with a a balsa spacer, drilled for bolts & the ends angled to fit the rake angle on the plan view. Balsa wedges were glued to the leading edges of the mounts to achieve the required side rake angle. The mounts could then be placed on the plan & the wing center section lowered into place. Check that the mounts were let deep enough into the wing ribs & using a dummy wire leg, that the retracted angle was OK. The outer wing panels could then be offered up & the outer corners of the mount chamfered to fit the lower wing profile. After much cutting & fitting (trial & error) the mounts were finally glued into the center section. The later photo shows the mounts in place & also the outer panels also glued . Flaps & hinges can also be seen. Observant viewers might spot a 'deliberate mistake'. Nothing too serious. Cheers John Quote Link to comment Share on other sites More sharing options...
adrian smith 4 Posted October 11, 2016 Share Posted October 11, 2016 The angles for virtually all "warbirds" is either less than 90 degrees or more! however there are articles on this mounting problem on this site. the only thing I will say is, when balancing the finished model, have the retracts up in the wing as many retracts when retracted move weight behind the balance point. also this also gives a forward balance when the wheels are down making for a more stable arrangement when taking off or landing. On your mention of this being probably the thickest wing on a warbird... I think the typhoon1b was deeper.(I could be wrong, if I am, I'm sure someone with greater knowledge will correct me). Quote Link to comment Share on other sites More sharing options...
adrian smith 4 Posted October 11, 2016 Share Posted October 11, 2016 Hi John, the full "retract travel for a hurricane is 95.5 degrees this allows for the forward angle when measured along the chord line looking side on and ensures that the wheels lay flat when in the wheel wells. Unitract ltd have info on this point and also sell the correct retracts for the hurricane. Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 11, 2016 Author Share Posted October 11, 2016 Hi Adrian Yes you are probably right about the Typhoon. Don't doubt the retract angles either. My retracts were not unitract prices though. Proof of the pudding. Cheers john Quote Link to comment Share on other sites More sharing options...
Nigel Day Posted October 12, 2016 Share Posted October 12, 2016 Looking really good John. Lots of elements I can learn from. Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 15, 2016 Author Share Posted October 15, 2016 Hi all, Just a few more words about the U/C. I've not tried to fit doors yet but so far it does'nt seem too bad. I wanted to fit sprung oleos so I was pleased to find a pair that looked as if they would do at a swap meet. A pair of eflight legs with a coil was also bought. I thought that I would be able to shorten the oleos a little if necessary. This proved to be impossible because there was insufficient material to allow another hole to be drilled & tapped. So 2 small compromises were necessary: the corner of the mounting u/c mounting flange had to be cut away slightly & because the legs were now slightly too long the wheels are a little bit undersized. All this could have been avoided if I had all the bits to hand before the u/c mounts were glued in place. Still, to make a virtue out of a necessity, it does give a bit more space in the wheel wells & the error will be hidden behind the wheel doors. Next time; joining the wing panels, bell cranks & linkages, skinning the wings. Cheers John. Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 17, 2016 Author Share Posted October 17, 2016 Hi all Joining the wing panels. I needed my extra long building board for this. The ailerons had been previously fitted, also the flaps had been hinged & of course the U/C mounts were in place. So we start with a careful check to see that all the ribs are flush & that the spars & ribs join neatly & with no gaps. Have a dry dummy run first with no glue & get the spring clamps & wing tip packing sorted out. The center section sits flat on the board on its rib tabs, a packing block is needed under the root rib tabs. I think I used gorilla glue on the ribs. The flap & aileron servos can be fitted & then all the bellcranks &wire links. Some care is needed to ensure that the flaps open & close in sync. Others might choose to use multiple servos but I stuck with the plan. The wing rib tabs have ensure that the panels have been built without warps. Until the wing s are sheeted,though, they remain very flexible. Balsa stand offs are tack glued to the front of the leading edge & the rear face of the rear spar. The wing can now be supported either side up while the bottom & top surfaces are sheeted. Rather than but the sheet over the joining rib I cut long splices over the center of the wing. The area above the flaps has been left open for now to provide access to the flap clevises. I had hoped that the flaps could be removable but it is looking unlikely because I can't get to the clevises from below & probably the wing underside will need to be finished & possibly painted with the flaps fitted before the upper skin can be finished. Leading edge can be fitted & shaped now. That's about it for now. Next back to the fuselage. Cheers John. Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 22, 2016 Author Share Posted October 22, 2016 Hi all Last time we looked at the fuselage the basic structure had just been completed. All straightforward stuff. Next job was to make up a steerable tailwheel. I couldn't think of a way to make a really scale u/c so a simplified unit was made up using 1/4' x 1/16' brass & a wheel collet. It's a bit more convincing than a bit of bent piano wire Next a start was made on the fuselage stringers. I began with the underside . The formers were glued in place & then the stringers were added, starting with the center stringer & then adding one on each side in turn. The stringers were stripped from a sheet of hard 1/16' balsa. Slots can be cut with a thin file in the formers one at a time. Check that the stringer is straight & glue in. Repeat for the next pair until finished. It takes time. Cheers John. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted October 22, 2016 Share Posted October 22, 2016 Looks Great John, though the weight at the tail might be a problem later..... Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 23, 2016 Author Share Posted October 23, 2016 Hi all For some reason one of the photos failed to upload on the last post. Danny I 'm hoping that the weight is not too much of an issue though it is a tad hefty. I did take off the corners & thin it slightly. Here is a more recent photo . Cheers John. Quote Link to comment Share on other sites More sharing options...
John Timmis Posted October 31, 2016 Author Share Posted October 31, 2016 Hi all, On with the fuselage. I forgot to mention gluing the tail pane seatings in position. After that the top fuselage can be built up with formers & stringers in the same way as the bottom. Then the "dog house" can be added. Next the front fuselage side formers are added & then the lower fuselage side sheeting. Next the front fuselage had to be shaped to fit the fibreglass cowling. The cowling is a nice substantial moulding. A hole was drilled for the motor spindle & then the cowl could be offered to the fuselage. Quite a bit of material had to be removed in order to achieve a good fit. I have a 10" disk sander which makes short work of this kind of job. This is a home made machine & is one of the most used machines in my workshop. It consists simply of a 10" plywood disc fixed onto the end of a old washing machine spindle. 80 grit abrasive paper is fixed to the disc with double sided tape. The hole in the front of the cowl was enlarged to about 70mm & a ply disc was cut so that the cowl could be clamped to the fuselage. The plan is that the cowl will be glued to the fuselage with the top part removable for fitting the battery. It's beginning to look like a hurricane. Cheers for now. John Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted October 31, 2016 Share Posted October 31, 2016 It certainly does John, you're doing a fantastic job there. To look right a Hurricane has got to be spot on, some "scale" efforts just don't look right. This one is clearly going to cut the mustard. Quote Link to comment Share on other sites More sharing options...
John Timmis Posted November 7, 2016 Author Share Posted November 7, 2016 Hi all Colin, thanks for the comment, glad that you like it. It's reached that rewarding stage now where all the hard work has been done in & each additional thing just makes it look better. Now that both the cowling & the wing could be attached to the fuselage the next job to tackle was the wing fairing.this is quite a prominent feature on the Hurricane. I like the way that BT has done this part of the design. Most of the fairing is built onto the wing rather than the fuselage. I've not seen it done like that before but it works really well. The front lower fairing was done first. Instructions on the plan simply say "make wing fairing from thick sheet & hollow out" . The side profile was traced & then 3 pieces were cut from 1/2 ' sheet . These were glued with more sheet & some triangle to form a sort of E shape to make the basis of the failring. So glue this onto the wing together with some thick triangular pieces on the leading edge & basicly you have a fairing. Attack it with the round sanding blocks & the jobs done. After this continue with the wing top fairing. All quite straightforward & very satisfying. Cheers john. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted November 7, 2016 Share Posted November 7, 2016 looks great John Cheers Danny Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted November 7, 2016 Share Posted November 7, 2016 Posted by adrian smith 4 on 11/10/2016 11:34:08: The angles for virtually all "warbirds" is either less than 90 degrees or more! however there are articles on this mounting problem on this site. the only thing I will say is, when balancing the finished model, have the retracts up in the wing as many retracts when retracted move weight behind the balance point. also this also gives a forward balance when the wheels are down making for a more stable arrangement when taking off or landing. On your mention of this being probably the thickest wing on a warbird... I think the typhoon1b was deeper.(I could be wrong, if I am, I'm sure someone with greater knowledge will correct me). Brian recomends setting the C of G with the gear down, I think he has taken into account the change as they retract. Cheers Danny Quote Link to comment Share on other sites More sharing options...
John Timmis Posted November 12, 2016 Author Share Posted November 12, 2016 Hi all, Danny , thanks for the tip re the undercarriage. I'm jumping out of sequence here with a couple of photos taken just a few minutes ago. So this is where it stands today. The reason for this is because I'm hoping to get some advice & opinions. The construction is now almost finished So this morning I put it all together, including prop,spinner , esc, battery & anything else I could think of & slung it up to check the cg position. As might be expected, it looks as if it will be a bit tail heavy. The whole thing , with a 6s lipo, weighed 8lb 11oz. But it is tail heavy, & not even covered yet. So it will need some nose weight. The battery bay is enormous & would easily accept a second 6s Lipo. This would bring the weight up to 10lb. I'm planning to finish with glass on the wing & doped nylon on the rest. BTs prototype weighed 10lb 2oz ready to fly but without fuel. So, the question is : " What is an acceptable all up weight?" Anybody who has built one please comment. The battery bay can be configured later. 2 batteries might be too much ???. I need to buy some new lipos anyway, any suggestions? Cheer John Quote Link to comment Share on other sites More sharing options...
Geoff S Posted November 12, 2016 Share Posted November 12, 2016 It looks absolutely stunning, John. It almost seems a shame to cover all that beautiful woodwork. The only suggestion I'm even remotely qualified to make is to delay buying any batteries until the very last minute when you'll be able to judge accurately just how much nose weight you'll need. Better to have an energy source in the front than lead. I've done several electric conversions now and every time they've needed as much weight up front as possible and this seems to be no exception. Geoff Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted November 12, 2016 Share Posted November 12, 2016 Hi John i have 6S2P A123 in mine so the equivalent of a 5S 4600. I also have a 1lb of sound system. Mine is around 11.5 lbs and I pride myself on building light i have heard of them often being heavier. Nose weight is the killer....but if you under 14lbs it will probably be okay Quote Link to comment Share on other sites More sharing options...
John Timmis Posted November 23, 2016 Author Share Posted November 23, 2016 Hi Geoff & Danny, thanks for the replies & the advice. Just what I needed to hear. I quite fancy the sound of a merlin up front.I think I could squeeze a 4" speaker into the bottom of the cowl underneath the battery. Does this sound about right? What is a recommended system? Getting back to the fuselage. The tailwheel & the control snakes were installed & then the stringers could be finished off on the fuselage sides. The decking for the forward fuselage has been built up as a separate removable item. It will, of course, be glued in place later but at the moment it gives better access to the cockpit & battery bay to leave it off. I intend to do just enough cockpit detail to take away the bare look & perhaps convince a casual observer. Cheers John Quote Link to comment Share on other sites More sharing options...
barry knight Posted December 9, 2016 Share Posted December 9, 2016 What a stunning build. Great work. I be you will e terrified to maiden this!!!! I am just about to maiden an RV4 that I designed and built.... Its on Own design blogs if your interested. I love the detail in this build. Especially the stringers on the fuse. they will look incredible through solar tex or equivelent I think. Loving the build. Quote Link to comment Share on other sites More sharing options...
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