Richard Harris Posted November 1, 2012 Share Posted November 1, 2012 Peter, I am sure they will be fine at 20g , the heavier the blade is the longer it takes to get them to spin up(a bit of shim can be added in this case to to give a little negative incidence). As they get lighter then spin up becomes easier but more left trim is needed for level flight. Each model will be trimmed slightly different because of this. Rich Quote Link to comment Share on other sites More sharing options...
Erfolg Posted November 1, 2012 Share Posted November 1, 2012 I have been anticipating a RCM&E magazine plan for an autogyro for some time. I note you are using the head from HK, and I am know considering buying a head assembly. It seems convenient to buy the spare blades also, although I note contributors seem to make their own. So why not buy in ready made blades? So is there any good reason why I should be cautious in buying a HK set of head and blades as spares Quote Link to comment Share on other sites More sharing options...
Richard Harris Posted November 1, 2012 Share Posted November 1, 2012 Erfolg, I know a few who have used the head and blades to good effect, there is nothing wrong with the way they fly but they are a bit flimsey. They just don't create the lift needed to fly the FF slowly enough for my liking. If it were built 200 g lighter then there would not be a problem. Nothing wrong with cobbling up something of your own? I am sure Tom's Crane Fly could easily be scaled down or lightened in some way. Sat at work last night having my 3am tea break and my mind started wandering as it does. I do like David's round cowl and thought a MK IV version may well be in order. Make the front of the fuselage more rounded and eliminate the carbon tube boom but instead stretch the fuselage backwards adding stringers. If the fuselage sides and base were 3mm light balsa instead of 6mm thick the weight should be kept rougly the same.....what do you think? long and sleek looking! Rich always thinking dept... Quote Link to comment Share on other sites More sharing options...
Grasshopper Posted November 1, 2012 Share Posted November 1, 2012 Catastrophe !! Completed my set of blades all weighing 21g with fg plate mounted, CofG checked and marked and then disaster - I have done the curved cut and glued the plate at the 'wrong' end. Question is for Rich I think - can I use these and have them rotating clockwise rather than as intended? Peter Quote Link to comment Share on other sites More sharing options...
Foamie Dave Posted November 1, 2012 Share Posted November 1, 2012 Posted by Richard Harris on 01/11/2012 14:54:22: Erfolg, Sat at work last night having my 3am tea break and my mind started wandering as it does. I do like David's round cowl and thought a MK IV version may well be in order. Make the front of the fuselage more rounded and eliminate the carbon tube boom but instead stretch the fuselage backwards adding stringers. If the fuselage sides and base were 3mm light balsa instead of 6mm thick the weight should be kept rougly the same.....what do you think? long and sleek looking! Rich lol..great minds My plans turned up today (nice one Rich ) so started a few mock ups in advance. Mine was going to be an EPP foam fus but that gave me probs with boom twist. I decided to extend the Pod, encasing the boom then thought why not just stretch the fus and go radial cowled retro racer Quote Link to comment Share on other sites More sharing options...
BILL PETTIT Posted November 1, 2012 Share Posted November 1, 2012 I'm not Rich I do believe that the blades can rotate the other way just as long as the leading edge is the blunt side. But it's always good to get the advise of the master too! Bill Quote Link to comment Share on other sites More sharing options...
Richard Harris Posted November 1, 2012 Share Posted November 1, 2012 Sounds like a plan Dave Peter, Don't worry too much, you aren't the first to do it and most certainly wont be the last! I have done it several times and did fly them on a pod and boom model 3-4 years ago. I am bound to have a video of it flying somewhere as I recorded alot of the experiments. You will however have to trim it to suit clockwise rotation and you will find it will turn easier to the right rather than the left as with anti clockwise rotating blades. Off the top of my head I would suggest a touch of right roll trim may be required. But the easiest way I find to get a model pretty close to flying trim is to switch on the model (important) then put your transmitter down. Holding your model above your head tip it back and walk slowly into the wind until the blades start to autorotate (you may need to give them a help in hand to get them started). You will hear them whistle to which the model can be brought directly above your head more horizontal. You will be able to feel it pulling as the baldes whistle, lightly holding it you can feel it pull one way or the other. Tip the model so that the top of the blades face into wind and slow down to a safe speed. Trim to suit and try again until there is no bias to pull left or right, when this is acheived it will be pretty close to flying neutral in roll. Rich It seems most of us prefer to do left hand circuits so I can only guess this is the reason for the norm to be anti clockwise rotation. It's opposite for the real thing so may be a prop torque thing. Found the video, this was in July 2009 ! crumbs!! Pod and boom type model with clockwise rotating blades, please turn sound off as the autofocus can be heard and its bad! You have got nothing to worry about Edited By Richard Harris on 01/11/2012 19:04:45 Edited By Richard Harris on 01/11/2012 19:05:40 Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted November 2, 2012 Author Share Posted November 2, 2012 Thanks Rich, avidly reading all the tips here. A little update. I've spent the last few evenings decorating the model, I've added an ESC, powered everything up, set up the mix and added the tail boom and feathers. So here she is...... The next task is to add the amended blade head attachment and, like Peter, I need to go and get some light balsa with which to make up some blades so I should be able to get to the LMS tomorrow. I'm quite pleased so far Quote Link to comment Share on other sites More sharing options...
Foamie Dave Posted November 2, 2012 Share Posted November 2, 2012 V Tasty !! . Looks the business David Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted November 2, 2012 Share Posted November 2, 2012 good stuff david.......try and keep it in one piece for the G/acre's do..... ken anderson...ne..1 ...G/acres do dept... Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted November 2, 2012 Author Share Posted November 2, 2012 I'll certainly try Ken Quote Link to comment Share on other sites More sharing options...
Grasshopper Posted November 2, 2012 Share Posted November 2, 2012 Great Rich, I was dreading having to start again on the blades. They are drilled and fitted now and with some covering they will be complete. I plan to do some rotational tests tomorrow with luck and some wind to see how they whistle. The rest is pretty well complete with just sanding and covering to do so I hope to be flying in a week or so. Photos to follow. Peter Quote Link to comment Share on other sites More sharing options...
Richard Harris Posted November 2, 2012 Share Posted November 2, 2012 Posted by David Ashby - RCME on 02/11/2012 06:07:02: I'm quite pleased so far And so you should be David !! that is a cracking job on the decorating Rich Quote Link to comment Share on other sites More sharing options...
Terry Walters Posted November 2, 2012 Share Posted November 2, 2012 Very nice David - looks the business! Brave chap! Looking forward to the maiden! Terry Quote Link to comment Share on other sites More sharing options...
BILL PETTIT Posted November 2, 2012 Share Posted November 2, 2012 Very nice job indeed David Bill Quote Link to comment Share on other sites More sharing options...
Bob Bertram Posted November 4, 2012 Share Posted November 4, 2012 Hi Rich, PM sent re purchase of drawings. Cheers Bob Quote Link to comment Share on other sites More sharing options...
Bob Bertram Posted November 4, 2012 Share Posted November 4, 2012 Hi Rich, The link works now! Cheers Bob Quote Link to comment Share on other sites More sharing options...
Grasshopper Posted November 6, 2012 Share Posted November 6, 2012 Last gasp on my build - just finished the mould for a fibre glass nose cone having failed to come up with any ready-made alternative. I have covered the mast and when the cone is ready and painted will be able to complete the covering. I did a weigh-in the other evening and RTF with a couple of estimates (final covering and nose cone) mine comes out at 764g. This is with a 3S 1800 LiPO and with a 3S 1000, 690g. Any idea what yours will weigh David? Part of the reason for my lightness will be that I omitted the structure under the main fuselage floor as I have used an internal snake for the rudder and also I used 3mm balsa for the top sides as did David I believe. On with the resin mixing and the messy stuff now. Peter Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted November 6, 2012 Author Share Posted November 6, 2012 Hi Pete No, I've not had a weigh yet. I've been busy with other things in the last few days so only managed a few little bits here and there. I'm going to set up the two head push rods tonight hopefully and then I'll have no excuse other than to make the blades later in the week. I'll try and get it on the scales this week too. Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted November 7, 2012 Author Share Posted November 7, 2012 It's been a bit hectic over the last few days - with the Dec issue going to press yesterday so I've only done little bits. Added the head and soldered the push rods and test fitted them but then realised I couldn't find my spirit level! So I'll return to that soon. I found that I had really set the two servos too far apart so I've had to cut slots in the fus side so their movement isn't impeded. It doesn't look too bad I guess. Pete, I think I'll be looking at an AUW of around 720g (1.72lbs) without blades. So with blades that'll be pretty close to your own figure. That's with an 1800mAh 3S Li-Po pack that itself weighs 132g. Motor is an Overlander 2820 size and swinging a 12x6 prop I'm reading 260 watts and 24 amps. Edited By David Ashby - RCME on 07/11/2012 15:07:57 Quote Link to comment Share on other sites More sharing options...
Erfolg Posted November 7, 2012 Share Posted November 7, 2012 Pictures are worth a thousand words, as they say. Those pictures of the head are illiminating, with respect to how they should be arranged. Is the mounting plate obtained from HK, as well as the head? How about the blades? Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted November 7, 2012 Share Posted November 7, 2012 Following the thread with interest...... I might be teaching grandmothers to suck eggs here but I thought I'd mention that when I was flying helis many moons ago we often used wooden blades. To get a nice smooth finish we used to cover them with heatshrink tubing. This was simply slipped over the blade and a heatgun passed over the tube to shrink it into place. Simple & very effective. Lots of heatshrink tube sellers on ebay...... Also we used to add weight to the blades to help with autorotations & also to get the CoG of the blade forward a bit.....as we all know from BEBs articles on lift, a stable "wing" has the centre of lift behind the CoG. This weight was usually in the form of lead rod about 3mm diameter let into a slot near the LE of the blade & secured with (lots of!!) epoxy.... I'm not sure if any of this is relevant to autogyros but thought I'd offer it up anyway.... Quote Link to comment Share on other sites More sharing options...
Grasshopper Posted November 7, 2012 Share Posted November 7, 2012 David, yes our weights will be about the same as my finished, covered, balanced blade set weighs 75g. I have not covered the fus. yet and had noticed on photos that there was some 'after-fitting' round the 'cockpit' to accomodate the rods. Tonights job in fact! Erflog Head - HK, throw away the mounting plate supplied. Mount plate - cut from .8mm fibre glass sheet and balance carefully. Blades - make them up in balsa/spruce from Rich' instructions and his diagrams. Balance carefully for weight and CofG. The blades from HK for the HK head have been discussed in this thread. Bottom line is they work - but are not for the beginner/faint hearted. Peter Quote Link to comment Share on other sites More sharing options...
Richard Harris Posted November 7, 2012 Share Posted November 7, 2012 Steve, May try the heat shrink idea, will have to have a surf and see what sizes are available. The FF blade is indeed like your heli blades, the mount hole position is set back 2mm from the CG position. This aids spin up and helps with blade pitch sensitivity causing out of trackness, tracking just adds stress to the mechanics and airframe. Peter, I agree 100% make sure the blades are balanced well, if you can get the balance within 3 mm of each other along their span. Then balance each blade with each other and add some sort of weight until they match (I use balsaloc). When you can grab any 2 blades and blt them together like a see saw between vice jaws etc they should all be in perfect equilibrium. Also you will notice that the blades have an angle at the bottom, this aids spin up aswell by adding negative incidence when spinning up. As you can see from the photo below I have been busy making blades and also another FFII, just so you know I have weighed each blade and they range from 26 g- 33.5g so the tolerance is quite large. From experience I would expect the heavier blade to maybe have a bit of negative shim added to aid spin up but only a piece of sellotape under the mating surface around the TE of the inner blade. The best weather to test fly is when it is flat calm, the blades have to be able to spin up in 0 wind conditions as well as a gale. Wind can give you a false indications that there is more lift than there actually is, it happened to me not so long back with my FF and some 2 blades I was testing. Nice 7-10mph winds saw the blades spin up nice. Nice steady ROG into the wind. As soon as I turned down wind it was appartant there wasn't enough lift and just sank until splat! So my advise is be patient and wait for the right conditions. Rich Quote Link to comment Share on other sites More sharing options...
Tom Wright 2 Posted November 7, 2012 Share Posted November 7, 2012 Rich I have a length of heat shrink wide enough to accommodate up to 2.5" blade chord ,your welcome to it if you intend to try this method . It would add enormous strength but add around 2.5 oz to each blade which is a bit much I think, maybe a thinner walled option might be available. Tom. Quote Link to comment Share on other sites More sharing options...
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