Model Boat Mayhem
Mess Deck: General Section => Other Hobbies and Interests => Topic started by: Andy M on January 12, 2020, 07:51:11 pm
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As my Sea Knight is mostly finished and I can return to do more work on it any time, I have already started my new project, another quadcopter powered helicopter, anybody got any idea what it is?
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Long round section tail boom! Could be a Russian Mil 8?
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Nope. I was going to do a cobra, but again, finding decent drawings was a problem. I was worried about rolling 1/32 balsa on a tight tube like this but it turned out not bad, I did the sheeting in two parts. Superglue to do the first bit of each and woodglue and pins to close it up. And well wetted balsa of course.
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Mil 8 looks nice right enough, need to add it to my list. Hoping to do a cobra as soon as I find decent drawings, at 1/19 scale to match the seaknight, it is about the same length. Also thought about doing skycrane at same scale, it comes out at 45 inches compared to 28 inch for seaknight, getting it within my weight limits would be a challenge tho. I built a skycrane for walkera 5#8 co ax helicopter, it flew but the rotor wash made the body wobble a bit. Sold to someone in germany. I have the video of it on my youtube channel. It ended up within my weight limit for the heli. The skycrane is pretty spindly so might manage 45 inch version within weight limit for my quad setup. The never ending build list. :-)
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Some amongst you may be wondering why I started building the tailboom first, main reason was that I wasnt that confident of managing to get 1/32 balsa round the thin end of the boom,which is 18mm diameter, without the balsa splitting. The rest of the helicopter body is even more challenging, with compound curves everywhere. So I picked the eaaier option. It also spurs me on to do the rest of the working out on how I am going to build the fuselage. I have got decent drawings this time and a reasonable bodyshell to copy from a cheap co ax heli, it ate one of its motors after about 10mins of first flying it, after buying 2 more sets of motors, I found out that 10mins is actually the longest I got from a motor! Ah well the bodyshell is good, my balsa one is going to be 3 times the size at 3 feet, so scaling up is easy. Building as light as I can, I hope to have the weight of the bare bodyshell with no motors, receiver or battery around the 200g mark. A bit of a challenge but I have managed to build the tailboom, horizontal stabilisers and fin at 20g. I have still to refine the sanding, which will take a small amount off this, then painting will put more on. Its promising. Undercarriage and glazing will add a fair bit, more paint. I need to keep it really light from the start as there are so many bits I cant lose weight on, I already made my first mistake with the tailboom, its formers are 2 layers of 1/32 glued together with grain running 90 degrees to each other forming superlight ply that you can cut into without it flaking off. There are seven formers, I was going to cut lightening holes in the inside 5, leaving end ones solid for gluing........I forgot, it was only after I had cut all my slots and glued the stringers in, ready for sheeting, but much too late for holes. Ah well. I am trying to design my fuselage as light as possible to compensate a bit for my error, I hope to use 1/32 balsa for as much of the structure as I possibly can, while being strong enough for a heavy landing.
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Here is my tailboom assembled. Anyone know what it is yet?
I have cut out all my body formers/bulkheads/frames, I have just to sand the edges to their finished shape and cut slots for stringers (longerons?) I have still to work out some of the parts to join all these together accurately, I am making it up as I go along so I will get these figured out soon.
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Looks like one of the umpteen Bell Jet Ranger derivatives.
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Correct. And its a complex shaped beastie to try and reproduce. Years ago I had a morley Mx ranger, flew it several times but never felt that comfortable with it as it was a major investment of time and money, so all flying was tense. This is my easy flying version. (If I get my weight within limits)
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More progress, formers cut out, still have some more work to be done, then I can start on cutting slots for stringers, maybe get some assembly done soon. Hopefully. Still working it out as I go along, next thing to think about is attaching my motors securely. The seaknight method worked well. Tight sliding fit with 3/16 balsa horizontal above and below 5mm square carbon motor tubes and 1/16 hard balsa going vertical front and back. It loosened off as I flew it a bit. Two tubes had moved out 10mm so a spot of Uhu glue where they meet the fuselage cured that and could still be pulled out easily if I want to. Anyway, I am thinking of the stucture around the motor mounts, the 'doghouse' (apparently) where the fullsize hides its powerplant and rotor drive system, this is is going to be a challenge to keep light, as it has to be strong too, and very well attached to the rest of my bodyshell. I am hoping to fit my control board in here and also my battery, which has to be easily accessible. Going well so far. I have two main formers in my bodyshell design, each one is a skid attachment point, so I figured they need to be strong. They are each made from two formers made from my doubled up 1/32 balsa superlight ply, separated by 1/32 strips, with a 1/8 sheet piece to take the skids at the bottom. I will put on photos that should explain them better.
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Rear skid former and the ones that go behind it. I have still to make the front one, it gets built at an angle though. Will tackle that tonight. I am pleased with progress so far. Should get to some construction soon. I usually do lots of test builds without glue to make sure every part is right before it gets glued. Still loads to do.
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Front skid former, the angled one, is built and sanded, still got 1/8 skid support plate to make and glue in place. I made a cardboard template to get angle correct. Also did a trial fit of rear formers onto my rear keel bit.
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Also shown in above photo is the start of the nose section, I will be having a go at moulding a clear nose section using my home made vacuum former. It did a good job of my mini, beetle and capri bodyshells. Due to the shape, I am going to mould it in two halves.
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Also of note in the photo is my trusty Spiralux fret saw, 0.5mm blade is amazing for accurate parts, ,if you steer the wood through it carefully. I have cut 1/4 inch birch ply on it, but it takes ages. On thinner ply and balsa it comes into its own. It cost me £80 about 25-30 years ago, but has been worth every penny, I have cut out parts for over 100 rc planes, about 20 boats, a pteranodon, a jackdaw, a sea eagle and several rc car bodies . I would highly recommend it to other modellers, but I dont think they are still available.
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Made up some of my 1/32 doubled up superlight balsa ply for my doghouse formers, woodglued, so I have to wait till they are dry before cutting them out. Also started building up my nose section moulds, using up scraps where possible. I had some 1/2 x 1 inch balsa I got in a pack. Too heavy for flying but perfect for this job. Long way to go before I can start carving and sanding. Times like this I wish I had bought some 4x2 balsa planks.
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My homemade vacuum table and some of the bodyshells I have produced so far. I am pleased with the results but they dont always turn out good, I heat the plastic in front of my shed stove so temperature is a variable, but experience helps judge the right moment to get it onto the vacuum table. The jetranger front end will be my biggest moulded item so far.
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A 'few' more bodyshells. I got a bit carried away. My friends took a few off my hands. Notice the extra bit where the plastic pulled in with a crease on the front wheel arch, superglue from inside, a patch of kitchen roll and a bit more superglue makes it strong enough to trim off the extra bit and sand flush. Didnt need to add filler as the superglue had filled the tiny gap.
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After using up a lot of my balsa collection, full 36 inch sheets and an assortment of scrap bits, I have built these, still have a lot of carving and sanding to do before I can try moulding from them. I really need to build the main frame of the heli soon, then I can sand my cockpit/nose moulds to their exact size.
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A good bit more progress, starting to look more like a jetranger. It's shape is showing me how difficult it is going to be to cover it with its 1/32 balsa skin. It is going to be done as a lot of differently shaped panels, some quite big, some just spanning one 'square', but they are not square. They will meet on my bulkheads, 2 layers of 1/32, so I will only have 1/32 on each side to fix my panels to. The fuselage is already quite strong, I am thinking of taking a bit out the insides of some of the files. I didn't want them to be weak tho, especially for sanding the frame, I have broken lots of bits on this and the sea knight might, while holding the fragile frames. Once the skins are glued on, the whole thing becomes more robust. I have added quite a lot of wood since the photo of it on the scales, it was 65.8g. I will be removing some more balsa before I put the skins on. Don't know if I am on track for my weight limit
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Due to the complexity, why not do as the fly boys do and skin it in tissue and dope, even A4 photocopy paper would be more pliable
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I notice the topic has been split, but wrongly named, its actually a bell 206 jetranger. I was going to ask Martin to change the title to quad copter helicopter bodyshell builds or something.
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The 1/32 balsa is the best weight to strength material I have. The sheets are 4 inch by 18 and weigh 6 to 8 g. I have used 12 sheets so far, fair bit of that has gone into my scraps box. The formers used up a lot. As the weight is only 60 odd grams, I have probably only got about 8 full sheets in the airframe, and a few bits of 1/16,1/8, 3/16 and 1/4. I had hoped to get it all made from 1/32 but some bits needed bigger sizes. I have made more lightening holes but don't want to go too wild. The tailboom will have a lot of leverage on the structure at the rear of the fuselage, especially in a heavy landing. I may try to shave some balsa off the inside of the frame before I put the skins on, it will all help.
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I have to say that I do intend building a cobra, but not yet, I need good drawings to start with. I am enjoying the jetranger build so far, skinning it will be a challenge. The good thing about the balsa as skins is that it is quite robust when finished, and doesn't say between bays like tissue would.
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Opps! Fixed!
Martin :embarrassed:
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Thanks Martin. I hope to do a few builds using these quadcopters as donors. I will start a new topic when the next one starts.
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More progress, nearly there with the nose section mould. It has taken a lot of sanding to get to this stage, I have to take a break from sanding for a while, my hands keep cramping up. I can get on with skinning the fuselage and making my landing gear. The nose section is close to being ready. I have marked out areas on my frame that I am going to remove, some can be done after sheeting but some need removed before sheeting goes on
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Quite noticeable on the nose is the patch I had to put in, I was sure I had made the walls thick enough, but I was wrong. No matter what I do, it will probably show up on my finished moulding.... Ah well, I can live with it, I am not doing another another one. Quite happy with how it's looking so far, I may decide the nose is finished, get my shed stove fired up and try a moulding. I have one bit of plastic that is a suitable size, but it's pretty thin, I am hoping it will get more strength once its the right shape.
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Plenty of room for control board and battery. Actually enough for 3 batteries. Other pics show extra window framing to support sheeting and a comparison with Seaknight.
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Fuselage sheeting was a challenge as I thought it would be, trying to get joins halfway on a 1/16 former has to be pretty accurate. Where the panel edges touch, it has to be less than 1/32 height difference, or it won't sand flush. I managed it though, hopefully with some sanding allowance. It didn't need much filling, most of the stuff in the photos will get sanded off. Well happy with how it's turning out. I still have more to do on my nose section mould, and sanding on the fuselage. Right side windows have been trimmed and sanded, left ones still to be done.
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Moulding time. I actually had the mould about 70% towards being usable but the edges hadn't pulled in right. The windscreen and nose looked really good. I tried reheating the plastic and remoulded it. It turned out as shown in the photo. Ah well. I need to make my frame bigger and get more plastic. It showed me that it's going to look good once I get a decent mould of it. And a rough weight of my nose section. 13g. The heavy duty balsa nose mould weighs in at a hefty 100+ grams!
I had the nose mould taped onto the heli body for a look and I decided to weigh it. Just over 200g, so the nose mould weighs nearly as much as the fuselage and tailboom. But...... with all the rotors, control board, battery and my knitting needle and marshmallow stick undercarriage (28g!) the total weight is still 25g under the Seaknight. It still has to be painted, but with a moulded nose coming in under 20g it will be about 100g lighter, unpainted and no dashboard/nose support. It will all add more weight but I know I have a bit in reserve. I will maybe get my radio area finished off and get a test flight soon.
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Have you thought of using that 1-2mm thick "styrofoam" type sheet the micro aircraft guys use. Can't remember the name but it's similar to the horrid non-disposable foam trays you used to get at supermarkets?
It's fascinating watching the build anyway. Reminds me of a competition I did at uni to build a boat from paper only. 10g max weight, to hold as much weight as possible before sinking. I still have it in my folks loft after best part of 25 years now!
Rich
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Hi Andy,
Not to steal glory but I found an old pic of my old paper model. A foot long. 10g total (NB all entries were varnished after, of course-paper is not waterproof!). In case it povides any inspiration. I'm trying to find the result (I know the paper of the results is in my folks loft with the model). I'm not sure if it held as much as 1.8kg now -just shows how much a little basic engineering can do. No doubt though if you crash it would just crumple an entirely paper effort I guess LoL!
....PS I got a special commendation for this, my Professors thought I was a crack-pot: I remember going round the Uni offices and stealing paper to take to the chemistry lab to measure just how much a single sheet of paper weighed. It was rdiculous, I ended up finding 2 or 3 sheets of something so thin! Very thin CA glue to stick it all. I had extra tube stiffeners in places but had to cut them all out to get back to 10g.
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That's the reason I like this forum, lots of different ideas, I can see how much work went into it. I did think about paper but to get the strength over gaps of 1/32 balsa, the paper was heavier. And my shed is quite damp this time of year. I am really enjoying my 1/32 balsa builds. This one is entirely balsa, the Seaknight had a few bits of 1/8 liteply, which are heavy, but worth it as they are in the nose. My Jetranger nose is proving to be a problem, see photos.........
As my last bit of clear plastic sheet failed to mould nicely, I thought I would practice on some white sheets I had. It proved that I would just have wasted 5 sheets of clear stuff.
Anyone good at vacuum moulding clear plastic? I would pay of course. I have tried and failed, its me, my machine or the plastic or my stove?
The rest of my jetranger has turned out better than I hoped, not having a clear cockpit is going to spoil the whole look. I have managed to get the nose mould down to under 80g (from 98!) still pretty hefty and definitely not clear.
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:o
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A bit more fuselage sanding and some balsa exhausts. Think I have sanded enough of the 1/32, looks and feels pretty thin in places, it was thin to start with! The hefty nose mould, 98 grams to start with, now under 80. It was never intended to fly, but I may use it for some test flights till I get round the cockpit problem. I think I could get another few grams out of it and still be strong enough to use as a mould. It is still under the weight range the quad can handle. So far, not painted the fuselage yet, think that will add a fair bit.
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It looks like you need to raise the plug off of the base so that the crinkling is below the moulded area. You can then trim to the needed size.
Jim
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I did have a post typed up with pics attached but there was an error, so here are the pics. 12 grams of paint so far. One coat so far.
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I will try raising my mould, next time the fire is on. I am a bit disappointed with results I have had, but its showed me where my mould needs tidied up.
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A couple of coats of matt black on my landing gear and it looks nice. I am making mounting blocks for the front crossmember. The rear crossmember I have also taken care of. Also decided to spend a few hours heating and pulling the best of my failed nose cones around the mould, pinning and taping to stop it all wrinkling up as I heated and pulled next bit. Took a while, but managed it with only small gaps shown. Also did same with thicker clear sheet and ended up with nice lower windows. Just the windscreen(s) to do, hopefully I can manage that.
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I have to say that the half decent looking failed mould a few posts above, I tried reheating it and it ended up as the one with big hole in the nose. So it was next best one, bottom right in group photo, which looked unsaveable but persistence saved the day. As long as my windscreen goes as well.
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Same technique, very tight on my plastic size, turned out well, I have to attach the windows to the white plastic, which has proven to be hard to glue. I will try contact adhesive on a set of offcuts, I know superglue just peels off it. I might try double sided tape if all else fails. I have to make up a support/attachment frame. The mould was oversized with a view to trimming to perfect fit later. This means my windscreen will have a section (3/16) taken out of the middle of it. I will have a windscreen centre support as part of my frame. Going well tho, I was a bit discouraged last night after so many moulding fails.
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Found that uhu glue seems to be working so I glued windscreen to nose section, I will be attaching the lower windows once it sets up solid. I need to get my mounting frame made up soon. It will need to fit nice to stiffen up the nose, the white plastic is flimsy, bit like the plastic used for strips of pills. At least I can take measurements from the mould.
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Got one lower window glued in, stuck to the mould, pig to get off etc. I also removed landing skids from quad motor pods as no longer required. They weigh nearly 3g, that's a 9 x 4 inch bit of 1/32 balsa's worth! Last photo shows it before it's first flight, complete with 80g nose mould and my new cockpit. Handled it fine but will be better once my nose is finished. Will be interesting to see how much it weighs when it's all mounted on the frame.
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Last lower window glued in. Didnt stick as much as first one. I have made a start on the frame. I don't know whether to incorporate a dash board? Maybe do that as a project later.
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My frame, and my windscreen halves. One has been trimmed to correct size, other one will get final trimming once first one is glued to the frame. Hopefully get a chance to do that soon.
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Final version of my frame and a photo of the frame and windscreen and nose etc taped onto it and on the scales. Still a few bits to do on it at this stage, is was far from perfect to start with. I am thinking it should end up a bit under 35g. Saved 45g over the balsa version and it's got clear windows. This project has presented lots of challenges, but I think it definitely looks like a jetranger, it flew OK yesterday with wood nose and plastic nose on it too, about 95g so with 60g less the flying time should be longer.
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Managed to get the nose to the painting stage, definitely looks better now it matches the fuselage. I can't wait to see it on the fuselage, didn't want to risk it while it's tacky, knowing my luck I would drop it. I have still to give the fuselage a second coat. Should brighten it up a bit.
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Couldn't resist trying it on the fuselage, it was still tacky but I only handled it by the windows. I think the fuselage needs another coat of paint. It's all added weight tho.....
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I was just thinking that as my model is about 1/10 scale, my 1/32 (0.8mm) skin would be like having 8mm balsa skin on the full size heli. Don't know if I would be leaning on the doors. Probably be pretty strong in reality, just not confidence inspiring. I have crashed a few model planes in my time and 6mm balsa takes some impact.
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This photo shows just how thin it is. Taken after a flight in my living room while wife was out shopping. She worries about the ornaments, but mostly the telly I think. Anyway, I never thought I would confidently fly a 3 foot jetranger in the living room. Decent flight time too, never thought to time it. I have 4 batteries anyway. No shortage of power. Was hoping to have outdoor flight today but its been windy and hailstones and snow for good measure. Definitely needs another coat of paint, or just stay with faded, patchy look?
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I decided it needed a tail rotor to finish off the tail area. It's definitely not heavy, under 2g with the shaft. The whole tailboom, fins and tail rotor are under 25g. I think it looks quite good. I might try a main rotor but don't know if I will have it on during flight, don't want a boom strike when I don't actually need a main rotor, would look good, I have had freewheeling rotors on my stubby sky crane quad body
they looked good when it was flying, took your eyes off the quad rotors. Also pained my exhausts gold over the silver.
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You never know - someone may come out with a full scale version of this some day, though it is an old concept, since if you watch the classic series thunderbirds they had jet versions (in the military walker episode).
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Here is some video of it flying, and the result of a slight crash, the tailboom was only damage, fixed in 2 minutes, just to wait on glue drying
Video here. https://youtu.be/5qzB2LgUZjU
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Thunderbirds helijet. Looks perfect for quad powering, anyone else fancy doing one? I already have a list of projects using these quadcopters.
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If you watched the video of the jetranger flying, twice it tips back and looks like its going to reverse into the ground, I saved it both times or it would have. I have been wondering what could cause this, I wondered if it was pendulum action of tail boom as I pulled back slightly to slow down. It is slightly tail heavy now I have the cockpit down to 30g. I wondered if it was because the horizontal fins are entering the downwash from rear rotors and being forced down. I flew it after I snapped the tailboom off, actually looked pretty good, never did the tail slide thing either. I will try it without the fins, they just slide onto a 1/16 balsa joiner, I have snapped 3 of them already, none from flying, all hanger rash. My tail rotor doesn't seem to want to freewheel like I thought it would, I did think about motorising it off my spare channel, but I never made provision for that when I was building it. Looks good when it's parked. I also wondered if my quad rotors are too close fore and aft, the Seaknight has same width over rotors but lots more length. Seaknight is 17. 5 inches, jetranger is only 9. Its a short pitching moment compared to the Seaknight. I suppose everything has its own traits. Still well happy with it, even with its funny habits, I am still amazed by how light it feels, the last jetranger I had was Morley mx ranger, weighing in at a hefty 8lbs plus. It needed a 45 engine to get airborne, mine is 3/4 the size and gets airborne on four small motors and a 7.4v 850mah battery! For about same length of time. In the living room.
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Just to prove it does fly in our living room. Not getting too adventurous though. Definitely no shortage of power.
https://youtu.be/N9UfYD933PE
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Jetranger has had a 2nd coat of paint on the fuselage, wishing I hadn't done my markings in pen. A lot of my working lines are still visible, but getting more faint. Still got to get another coat on the nose section. I flew the jetranger on Thursday, taking care to make the transition from flying forward to slowing down as smoothly as I could, I managed to avoid provoking the dreaded tail slide. I can tell the fore and aft control is increased due to the quad power units being closer together. It also has less leverage to recover from forward and back movements especially with the long pendulum of the tailboom. Now that I know how to avoid it, should be fine from now on. Hopefully.
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Having decided that at least part of the handling quirks are down to the fact its a bit tail heavy, even though the actual boom and fins are around 1 ounce, the tail rotor added a bit, I forgot to weigh it but its more weight really far back. When I flew it with wooden mould on front, it crept forward, now with my lightweight nose, it more than creeps backwards. I think I am going to add some cockpit detailing to put some weight up front, I have more than enough power left. It will be pretty basic, I am going to fix the perspective of this photo on photoshop, get it printed,stuck to a 1/32 console and hey presto, a nice light instrument panel. Maybe some front seats too. Nice foam carving exercise. If it's still not heavy enough to balance the tail, I was thinking I might have to move the battery forward into where the rotor comes out of on full size.
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I made a start on the cockpit detailing, I hadn't noticed the big pillar just behind the front seats until I started researching the jet ranger, I have even been in one twice, there is also a a sort of half bulkhead that the backs of the seats attach to. I have already made and fitted the pillar, made the bulkhead and got foam blanks cut out for my seats. I was going to do them from balsa but decided hollow non load bearing foam will be light enough. I am leaving the bulkhead and seats unglued until I am sure I don't need in the back seat area, for pillar painting. I am probably only going to do front seats. I also made a start on my rotor blades, 8g for the skins, before I started adding bits. I have 1/32 bottom skin with 1/8 x 3/16 glued along front edge, 1/16 tiny ribs blended to chamfered lower skin trailing edge. This has been sanded to 0.4mm (1/64) approx. Also added were crossgrain 1/8 softish sheet tips and 1/8 hard balsa root block. The top skins have been glued on with pva. The top sheeting trailing edge overlaps bottom one bringing thickness to 3/32. Pinned to the board with 100 pins, no idea how strong they will be once they are dry, I might end up having to remove them for flight, will give it a try anyway once they are finished.
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Bulkhead sat in position against pillar, foam seat blanks ready for carving and a pair of blade blanks, still to be sanded etc. I need to make up a rotor head as well.
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8.2g blade blank sanded down to 7.6g, I thought they were both the same weight as they were made from 2 balsa sheets the same weight. Anyway, the other one is 6.2g! So I need to add 1.5 g to it. Or I should really wait till I have made the rotor head and balance it then, this will probably be 1.5g of solder and a hole drilled up the end of the blade. I haven't weighed out the solder to see how long it will be. The seats are 3g for the pair unshaped, bulkhead is 1g, I might cut holes in it behind the seats. I reckon the pillar is another gram. Not started on instrument panel yet. Rotor head will add a fair bit. I am considering sacrificing my walker a 5#8 coaxial helicopter to provide my rotor shaft. It had a long service, well over 1000 flights. I tried it about 6 months ago and it wasn't flying right, kept flipping back and to the side. So it's probably going to get stripped. The jet ranger needs a rotor, even if it only gets used for display purposes, I will try it in the air if I get it light enough, but even if I can get it turning on the ground, I will be well happy. It will be weight in front of my quad rotor centre, just don't know how much yet. Blades will be 15+ as they aren't painted yet. So it's goodnight for the walkera. Its rotor shaft is going to be perfect, just need to add some structure to my airframe to hold it firmly. Will get into some dismantling later. Photos show how thin my outer skins are and a few pics with the sea Knight.
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Found this on Facebook Andy! {-)
(https://www.modelboatmayhemimages.co.uk/images/2020/02/12/84723630_169272314492281_8471382400729874432_n.jpg) (https://www.modelboatmayhemimages.co.uk/image/ZioD9)
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That's brilliant. It is definitely recognisable as a piasecki h21 flying banana. It probably weighs more than my jet ranger.
Here is a full battery flight in my living room when the wife popped out. I bump into the dogs bed at one point. Also close enough to furniture to have caught the rotors if it had been a normal helicopter..... I love it. Hopefully get a chance to work on interior and rotor head later on.
Nearly 6 minute flight on 7.4v 850mah battery here. https://youtu.be/CK0xhH-EZNw (https://youtu.be/CK0xhH-EZNw)
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Having been kindly given a bigger set of ditigal scales by my mum, I have now weighed the jetanger accurately. All up ready to fly, including standard 7.4v 850 mah battery at 46g it weighs 365g! Quad parts and battery add up to 167g. This means my airframe weighs 198g, with skids, cockpit assembly and fake tail rotor. Can't remember how much those bits are exactly, think it was 30g each for skids and cockpit and under 5 for tail rotor. Puts my actual balsa fuselage in about the 135g mark. About 45g per foot. It is so much lighter than it looks. Really enjoying flying it and still having projects to do on it, not many helicopters you can fly before you have finished building the main rotor....... Photo shows my almost finished rotor blades and the tool I used to cut 1/64 ply reinforcement discs I am gluing to my blades. Hope to start on rotor head drawing later. The drumstick is for poking the discs out of my cutter.
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I forgot to say that for cutting the discs, I used the cutter in a cordless drill, gives a nicer cut.
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Here is the shaft I am going to use, stripped from walker 5#8. I don't know if I am going to use the other bits until I start properly on the rotor head. It is ballraced, so it's got the best chance of actually spinning.
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Blades finish sanded, spray painted matt black. Black paint had soaked through the wood, under the tape. Tape was rubbed down but wood is really absorbent. First coat of yellow on tips. Need to get stuck into doing my rotor head soon.
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Another coat of yellow on the tips helps, maybe one more to do. Rotorhead and blades are nearly complete, quite heavy at 30g but it's quite a big structure. Rotorhead is 1/4 hard balsa with 1/16 ply top and bottom, balsa details. I had to add 1.3g steel rod in the tip of the lighter blade. Managed to break through the surface when I was drilling the hole for it....... I am a bit worried about running the rotor system on the heli, don't want to slice my tailboom off. The blades are only 8g each but still a bit of momentum once you spin them. I will proceed cautiously, flying with it will be interesting, don't think it would handle forward flight too well, a huge mix of aerodynamic forces on a superlight structure. If it works for hovering I will be happy. If it even just spins in the downdraught when it's on the ground , that would do as well. I need to open up my top sheeting for the rotor mast and see what I can attach my structure to. It's all pretty light up there but there are bulkheads I can attach to.
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Here is the rotorhead with detailing and a bit of paint. Looks good enough for my purposes and I didn't want to add any more weight. I still have control rods and base to add but the rotor system is within the 50g that I have available, might even manage enough leftover to carry my seats, bulkhead and my planned instrument panel, which I haven't got round to yet. Cutting out the areas behind the seats on the bulkhead took 0.3g off. Tiny amounts, but worth removing it. I am also going to hollow the back and bottom of the seats. Be interesting to see how much they come out at. They were 3g for the pair, unshaped. They have been shaped and a coat of paint added, one more to go. I am hoping they will still be around 3g painted and hollowed.Last photos show the magnet and kebab stick breakaway system on my tail fin. It's been knocked off about 50 times so far, so it's doing its job. The horizontal stabilisers have a 1/16 soft balsa joiner, which breaks easily, none when I have been flying/crashing but I have snapped 3 of them in my workshop. I flew it outside yesterday for 4 full battery flights, it still did the tailslide thing, a few times hitting the ground quite heavily, but no damage. I am getting better at avoiding the tailslide but I still get adventurous. Had 2 living room flights today, narrowly missing wife's vase of flowers while practising a table landing. It is very stable apart from me having to hold a bit of forward on all the time. Extremely slow movements are possible (even if they are not visible in my videos, lol) Once I get my balance point forward a bit it should be perfect. Loving it so far, just wish my living room was bit bigger! Ha ha.
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Rotor system freewheel test video here https://youtu.be/7y8xNtBdJ20
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Here are my seats, weight over 2g each so a bit of hollowing on the back and under seat. 1.7g each, so bit more hollowing gets the pair down to under. 3.14g good enough for me, nearly broke through a couple of times so that's enough. Last photo is my rotor system weighing in at over 30g. Only got to attach it now. And make sure it is removable.
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I was quite impressed with the way the rotor freewheels, I am pretty sure it will spin with the air getting sucked down towards the quad props. I always hope for the best, but can cope with just having it for display if it doesnt work or looks like its going to slice my tailboom off. I hope to get that mounted over the weekend, I dont think I will test it indoors though, especially now I am used to flying it without it, I will need to stay a bit further away from things now
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I couldnt resist, and in the interests of structural testing of my rotor system in regards to it coming apart and detroying my jetranger, I have now tested my rotor system in a cordless drill, to rpms far in excess of what I expect it to be freewheeling at. I only went to 3/4 throttle on speed 2 but it was fast enough for one hand. Pretty sure it would have taken the rest. I have to say that my main rotor shaft is just a really tight fit in the rotor head, another reason to be backing off when I did, according to drill, its full speed is 1400rpm. I was probably at about 1000, with something that weighs 30 odd grams, quite amazed it held up, the right material in the right places. I had thought my fake balance weights on top might have flown off but they stayed put. Having now tested it, I need to see if I can actually fit it. I have restricted my access a bit inside by adding the central pillar. I might have to cut that back out to let me inside the fuselage to add structure for bottom end of the rotor bearing block. I should manage the top bit from outside, still have to make up a set of dummy control rods and the gaiter and link thing that goes on shaft just inside rotor opening. I just keep getting a nagging thought in the back of my head, saying, why are you adding the possibility of a tailboom strike to a helicopter that doesnt have that possibility. I dont know really, I just want to see it flying with a proper rotor disc showing its yellow tips, even if it just trundles round, will be good for some photos. Next bit of testing I am really looking forward to is trying it on the fuselage with the quad motors sucking air through it, I might try a temporary setup to see if it will turn, before I cut holes in my nice fuselage. I may just have two cross bits of 1/8 balsa with holes if the rotor system is just for static use.
Cordless drill test video here. https://youtu.be/w-z4pF8FZgI
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Well that has decided that for me, I have clamped rotor bearing to bit of wood and taped a quadcopter underneath, as it would be on jetranger. Ran quadcopter up to full speed, not a sausage, the rotor never moved. I tried helping it by spinning it but it just slowed down. Ah well, static display it is then. Couple of bits of balsa to hold it. I was worried about it chopping my tail off anyway.
Ok so that doesnt figure into my flying weight anymore, so my cockpit detailing can be bit heavier/more detailed. Might even manage a pilot, foam, rough hewn with angular, granular kind of appearance. Lol.
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Noticed there is so angle of attack on the blades, so they wont rotate with the flow of air until it is in the air and dips forward or back, the angle would also have to be quite big as well, as a little wont have enough of an effect. just my thought :D
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There is a small amount, around 3 degrees.I have built autogyros in the past, so I know 3 degrees isnt much, I did hope that all the downward airflow would do the trick. To be honest, I was worried about carrying it about on my heli due to aerodynamic forces through my fairly flimsy rotor system. I will finish it for static display, its a bit late to change blade angle now anyway. I will finish off my cockpit and that should help with the tail heaviness. Apart from that, I think I have ended up with a nice model that turned out a bit lighter than I had hoped.
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I decided to try the jetranger with an extra battery as ballast in the nose section. It weighs 46g, so its still close to what i thought was my weight limit, it cured the tail heaviness, but looked as if it was struggling with the extra weight. So I removed it and my decent performance returned immediately. I know it sounds obvious to use the transmitter trims to try and stop it creeping backwards but I was hoping to be able to balance it properly to avoid adding trim and having rear motors running hotter, as they have gained a reputation for burning out from what I have read online. I have not had any burn out in normal use, I have a standard quad that I use for excersising the dog, it has had at least 2 batteries worth of flying almost every day since october. Some days I take it flying after the dog is worn out so it has a lot of time on the motors. The dog has killed 2 motors on it, biting the quad, but I dont count them as its not normal flying loads. The jetranger has had about 60 flights now, probably more on the seaknight so far, no motor burnouts. I did oil the motor shafts and the propshafts, then the motors were run in gently with no propshafts fitted, which seems to have eliminated burnouts from the start. I am loading my motors up way beyond the standard bodyshell with no visible effect. My radio/battery compartment has mesh on sides and top and holes in its floor and it still gets pretty warm, mostly from the battery, but its not excessive, just a warm painty smell. Lol. So as I was writing this, I decided to try adjusting the trim forwards. I thought I would have to put loads on but lo and behold (why didnt I try this earlier?) 3 clicks of trim was all it took to stop it creeping back. I am still going to do some lightweight cockpit detailing which might mean it only needs one or 2 clicks of trim, but I just wished I had tried it earlier. Ah well, it has honed my flight skills a bit more. I havent flown it outside like that, it may still have a pendulum effect from the tail boom, which I think is also affected by rotors being too close, I didnt really have an option, there wasnt enough width for the rear motor beams to be supported properly. I may still do a 4 foot version. Just to see if it did handle better with rotors a few inches further back, at a bigger scale, I would have more width to move it back further still, bearing in mind that at the moment, the jetranger rotor spacing is 9 inches, front to back, the seaknight is 17 odd. It doesnt display the same tendency to tail slide. I was thinking also of taking my tailrotor off as its not doing anything but adding to the tail heaviness, I would like to try a clear plastic but painted to look as if its spinning kind of idea. I tried it before on a walkera co axial heli, looked better than a bare tailboom but needed refinement. Lol. I sanded a disc of plastic by spinning it and scratching it up a bit then some diluted yellow paint for 'tips'
It was meant to be seen from a distance and it is definitely much better that way! I have a video on youtube where I spin the jetranger tailrotor up with a compressor, it looks good, the video should help me with getting a plastic disc to look reasonable. I would still like to spin the tailrotor but I hadnt planned for that, I thought it would freewheel in disturbed air, another ah well. I am still finding it amazing that I can fly a 3 ft jetranger in my living room,and precisely, I am getting better with it now, quite a bit of practice indoors recently, well, when the wife is out. I need to finish the cockpit off, still thinking about a carved pilot, he is going to be the hollow man. Lol.
Having written about flying indoors, I had a chance to get a couple of flights outside when the wind and snow/rain stopped fot 15 minutes, still does the tailslide thing, knocking my tailfin off a few times before I just went without it, a noticeable improvement, I even tried provoking it, I am either comfortable with it or just mad to try that, but I know its pretty tough. I think my tailrotor is heavier than the fin, I will try and see if I can get it off without damaging anything. Help with the tailslide thing. Gradual refinements are part of the fun. Broke one of my marshmallow stick skids, right where I knew it would break if it was going to. Superglue, fixed, but probably not same strength. Not bad for damage from 60 odd flights, and the snapped off tailboom a while ago.
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That's surely official then, I don't write the longest posts! Think you might have to break that up a bit.
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I didnt realise I had written as much as that till I pasted it in there. Lol. Anyway, I got my tailrotor off without damage and was surprised to find out that the fin is much heavier than the tail rotor.
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Broke my landing skid again today, I tried flying the Jetranger in a bit of wind today, but it doesnt like it, its fine going into wind and tracking side to side, but as soon as you try to turn it round it does funny stuff trying to spin the tail into the wind. Bearing in mind that its only speed difference on a set of props that turns it, incredible really, especially in a fair wind. I got turned round eventually and headed downwind a bit and tried to turn, tailslide to the ground and rolled onto its back, only damage is tailskid though, so not bad. I love the durability of these models, I just know if I had done that with a 'proper' helicopter, I would have broken blades, bent shafts and probably ripped the tailboom off too. Also, being scottish, I like the fact my transmitter, receiver/speed controller/multi gyro unit, motors, gearboxes, props, battery and charger all adds up to £12!!! I havent managed to find any as cheap as this again, still, even at twice that price I think I would still buy them. I have paid more than 24 quid for a hitec micro servo back in the day, I actually bought 2, fair bit out of my wages then. I am getting through my stock of quads though. Lol. You even get a rubbery bodyshell you can paint up. This is first gloss coat over white spray primer.
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Bit more done on interior, wife chose colour scheme inside. Got a lot of bits I want to add in the cockpit, should be a nice sub-build, even though you dont really notice as its flying about.
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Seats painted, floor glued in. Centre console part made. I was wondering what I could make the collective pitch levers from, then thought I would try making dowels from balsa using my tx aerial cutters, what a job they did, i burst through the side of balsa at the end but I have enough for my levers, slightly thicker sections are for handle/throttle. The aerial sections dont even need any sharpening, they work straight away. And its recycling. I should really try them on plastic kit type material. I think if you went slow and gentle in plastic to avoid melting they would work. Just think, perfect portholes! I have used mine a lot now, from perfect holes to nibbling little bits of foam out of my seaknight bits. Another one of these 'why didnt I think of that before' moments. Anyway, I hope to get more work done on my interior later.
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While waiting for my giant wasp to dry, I decided to paint my jetranger interior, which dried quick enough to be able to tack glue my seats in with copydex, which is still fine after 10+ years! I know one seat is squint, I fixed it after the photo, I still have bits of the interior to paint, I will need to make an angled brush for some bits, just the front at the moment. I cant really afford any more weight in the back for rear seats, but it would finish it off. I have glued my centre console in, next job is the instrument console. I want to do a foam pilot too, probably in the 10-15g range? Will see what weight it turns to be. Foam carving is quite enjoyable, I did several drivers for our rc minis/beetles. This is a bit bigger scale, 1/10, so less fiddly.
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I am still undecided about doing the rear seats, I could probably manage them and a top bit of bulkhead at around 10g painted? Its still behind the centre line, so critical really.
I have come to the conclusion that at least some of the flying problems are caused by the control board being a bit far back, I need to do some measuring and see if there is a way I can move it forward, even a bit to see if that helps any, if not, I will have removed some more balsa. :}
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Another problem with the rear seat idea.........I need to install them through the rear windows. Bit of a challenge in itself.
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While taking a rest from producing giant wasps leg parts, I decided to see if I could actually manage to move my jetranger's contol board forward to bring its centre closer to the center of the front and rear props...... Some balsa removal, as much as I dared, and still not that visible through the intakes and then a try sliding it forward into my newly created area, and lo and behold..... Its close to being bang on centre, few mm at the most, an inch forward has to help, I am certain, might still get the pendulum tailboom effect, though. I am hoping my cockpit detailing will help that, its all extra weight up front. I probably will make seats and bulkhead for rear, it will actually all be just in front of my centre line/centre of gravity, not behind as I was thinking? Getting it all in the windows is going to be fun. Its definately a bit late for doing a floor like the front, and the seat will probably have to be separate back and seat bits, the front one's L shape was easy to work with, but window is not big enough to get that shape through.
Anyway, I am waiting till the wind stops outside so I can try a test flight and see what difference there is from moving the board . Must be some, it was good bit out. Towards the end that was misbehaving. That and the cockpit detailing should have the beast tamed a bit. I am amazed at some of the heavy 'arrivals' its has coped with, for such a light structure. Even with its handling faults, uneven panelling (caused by trying to replicate compound curves with balsa that only curves in one direction) and fairly delicate skids, I really like the jetranger, years ago, I was saving up for a kyosho electric jetranger, somewhat smaller than mine, but it was close to £200 and I still needed to buy micro servos as well, they were £25 back then, motorbike parts took the funds and I never got it. But now, I think I have an even better one, for an outlay of about £30? Including all radio, motors and battery. There are a good few hours of work in it, but I enjoyed all of them. The kyosho one had no chance of getting a cockpit, it was stuffed with gear in there. Their body moulding never looked that good either...... not that defined. My ones radio etc is all up top, leaving a big empty cabin. Maybe get some sketches done for a foam pilot blank.
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Wow, what a difference. I flew the jetranger in the living room and it is transformed, no more signs of it tailsliding and there doesnt seem to be much pendulum effect from tailboom either. I was giving it extreme movements and it was doing what I was telling it with no signs of anything bad. Perfect,
Short test video here
https://youtu.be/unnP4I-xP40
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After long deliberation, I am not going to do rear seats, the front seats etc have added 5g and I haven't made the instrument console yet, I can notice the difference in performance easily, the punchy climb out is a bit reduced now. Still plenty but definitely loading it closer to limit. The battery gets quite warm after a flight. Settle for what I've got so far.
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I had a flight with this today, it has had well over a hundred flights so far, I am still impressed with how it turned out and how much more comfortable I am flying this rather than a 'proper' helicopter. Every time I pick it up, I am amazed how light it is for its size. A 3 foot long jetranger that weighs 325g, my morley mx ranger was only a foot longer and it weighed about 4kg! And how cheap it was to build it. Around £30.
It does warm it's battery up quite a bit, but doesnt seem to do any harm. I have plenty of spare batteries for it anyway.
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I have been having a good few flights with the Jetranger, it isnt a true helicopter, but so far, I am actually preferring it to the real heli's I have had.
My Morley MX Ranger was over 8 pounds and with its 4 foot rotor span it was well into the 'dangerous' category.
It also suffered damage easily... While it was on the ground, a little rise in revs as the fuel ran out was enough to flip it on its side.... Bent mainshaft, cracked blades etc and a helluva fright.
My new one is 3/4 the size of the morley and I can fly it indoors if I want (my wife isnt here just now, or that just wouldnt be happening)
If it does tip over, it doesnt seem to damage it, so far, its only real weak point is one of the skids, they are bamboo and drilled to take the undercarriage legs, this creates weakness, I have repaired it a few times but may have to visit my mum and see what she has in her knitting needle collection, I cant find bamboo sticks that size anymore or I might have tried again with fresh ones.
Even though I made it, it still surprises me just how light the jetranger feels, even when the battery is in, it still feels like it should be much heavier than it is.
During construction, I never had a scale that would accurately weigh the whole thing, as soon as it got over 100g, I had no real idea of its weight.
I now have a better set of scales that read up to 5kg, that will cover nearly all my model weighing requirements.
So.... Final weight, ready to fly....
370g. It is 322g without the battery, it turned out my cheap kitchen scale estimate in the last post was only 3g out... It is good to know exactly though.....
Maybe not as light as it feels, but it is 3 feet long.
It works out at about 10g per inch, and that is including electronics, battery, carbon rods and motors, gearboxes, props, knitting needle and bamboo landing gear etc, etc.
I did fancy doing a 4 foot version but if it was much over the weight of the 3 foot one, I dont think it would fly as well. As it is, it can power out of a fairly rapid descent so I dont want to risk anything heavier.
I just need to fly it closer to make it look bigger😁
One more major advantage... It cost so much less. The whole quadcopter, charger, battery, and control was £12 and there is about 12 to 15 of balsa.
I am still glad I bought a good few of the quadcopters when I had the chance. They are the cheapest way I have managed to get something flying with radio control.
And you can do it indoors if it is raining.
Does stirr up the doghairs a bit though.....
The morley jetranger had £250 JR radio in it and a £70 gyro, the heli and engine were another £400 odd. And that was about 30 years ago, I have had motorbikes that cost less than that.
I know my jetranger isnt a 'proper' helicopter, I can live with that, I managed to get the shape not bad, considering it is made from flat balsawood.
It doesnt pump out castor oil, but it is still pretty loud, compared to running just a bare frame quadcopter, the fuselage amplifies the sound a bit.
I still have 2 'spare' quadcopter setups, and some 1/32 and 1/16 balsa, so I may be doing another quadcopter body at some point, I still fancy another Sikorski skycrane, I thought about doing it to same scale as my vertol/seaknight, but it would be a fair bit bigger, so I would have to go (even more) extra light construction. Especially if I wanted to keep my power reserve.
I do have vector 'board' at 0.2mm thick that I thought about using for non stressed areas, it is pretty flimsy stuff. I will find a use for it eventually😁
I have a lot of projects and potential future projects in my head just now, deciding which one to concentrate on is the difficult bit, and making best use of materials I have, rather than buying more.
I have spent a fair bit on my modelling recently, I do feel a bit guilty about it but building my pair of Javelin speedboats has helped keep my spirits up at a very difficult time.
I am on economy mode now, I still have enough for a couple of boats and another quadcopter creation, I have done a jetranger, a seaknight and a giant wasp so far......
Any suggestions for the next one?
The Javelin is for size comparison.
The jetranger would need to be a bit bigger to be action man sized.
I cant believe how far my pot of yellow paint has gone.... Lol.
Off the top of my head, it has done a Jetranger, 23cm cabin cruiser, 18.5cm tug, mini size vic smeed Rorqual, a Lesro Javelin and 2 different sizes of giant wasp, and thats just the radio controlled things.
The original 5 litre pot also did my full size minimost boat! The rest were painted from what was left over.
Thats what I call coverage.
I need to get all my yellow models out in the garden for a photo.
Sadly, my minimost rotted away. Models are a bit easier to store. 😁