MattyB

The BMFA will not be recognised by newcomers as a governing authority (whether they are or they aren't), and the CAA have stated publically they do not investigate or enforce anything to do with drones. As a result to have any influence with Joe Public I suspect any note would have to be signed by the Police, a group whose purpose and role is understood by all. The chance of that happening though must be near to zero... On the two occasions I have tried to engage law enforcement to address illegal drone flying the officers in question have had no real knowledge of the law with respect to SUAS, nor any conspicuous desire to enforce it. I suspect this is part of the reason the current EASA proposals aim to make most flying legal only in predetermined places, that way any officer can quickly and simply identify if a drone is being operated illegally simply by location. Edited By MattyB on 19/04/2017 02:09:54

The above explains why you do not see many low Kv small motors - they are harder to make with very thin wire and can't carry enough current to be useful on lower cell counts (no-one wants to run 6S on an indoor F3P model!). The reason bigger motors tend to have lower Kv is I guess more about limiting max currents and RPMs - it's much more efficient to minimise I squared R losses (heat) in your motor and battery by operating at higher voltages and lower currents. An added bonus is that it's easier to engineer a heavier motor to drive a larger prop if it's turning that prop more slowly. This is important to the budget manufacturers who can produce more affordable large motors that don't require the absolute best quality bearings etc. Edited By MattyB on 19/04/2017 01:50:34

Posted by Erfolg on 18/04/2017 22:45:01: Intuitively we all seem to favour a 4S set up for this project. As I have written previously, others have put forward sound practical reasons, some based on availability of equipment, some relating to specific apects of current flow. Yet other than a universal gut feel, non of us has put forward a technical reason relating to motor design. It does seem that a 3s motor could produce something like the power i am looking for, albeit with a rather bulky, hence heavy motor. Although the all up weight of a 3s motor and Lipo could be similar to a 4s set up. We all would say a 6s set up on an indoor model, will not work very well. We all will say that a 2s set up on a 20kg model does not compute. All I am looking to establish, what is it about motor design and voltage, that pushes our decision making one way or the other. This article may help you Erf. I think the key thing to understand here is the relationship between the number of winds (turns) on the motor, Kv and how the two affect the ability to carry current because of the wire gauges used... "In summary, a low KV motor has more winds of thinner wire - it will carry more volts at less amps, produce higher torque and swing a bigger prop. That may sound confusing, but compare it with a high KV motor which has less winds of thicker wire which will carry more amps at less volts and spin a smaller prop at high revs." Edited By MattyB on 19/04/2017 01:38:05

Posted by Chris Walby on 18/04/2017 12:46:11: ...With high KV motors dropping prop size (pitch or diameter) is generally not an issue, but extracting high powers out of low KV motors leads into all sorts if problems....don't ask about trying to get 1200w out of a 370KV motor as the prop looks like its fallen off a wind turbine! Not needed for your application....but two 3S packs in series will give you 6S if its performance you are after. If you have a motor of Kv of lower than ~600 you are going to be looking at 5S at least, more normally 6S (IMO 5S is never a good choice as there is a smaller selection of batteries available, and to use smaller packs in series will require a mix of 2S and 3S batteries). For example on my Miss Wind I use the stock setup to generate 1100-1200W - a 470Kv motor on 6S and a 16x10 or 16x12, pulling (from memory) 55-60A. Try to generate that much power on 4S and you would require a ginormous prop, as well as pulling currents that would require a much larger ESC and be generate much higher heat in your batteries, shortening their life. Posted by Chris Walby on 18/04/2017 12:46:11: If you have some 4S packs, work with them, pick a 500 to 1000 KV motor & follow the advice from the others about prop size if the motor manufacture does not give a guide size.... Lastly use a power meter just to check current/power at full throttle to make sure you are not exceeding motor/ESC maximums This is very good advice - go with it!

It's all in the manual here...

We ran up Dad's new toy in his garden this afternoon, a Roto 85 FSI inline twin with my daughter on the sticks - sorry for the wobbly camera work, she was quite excited as you can hear...!     After just over an hour of total running it is hitting ~5700 rpm on 25x10 Fiela prop, making a calculated 5.7hp. It throttles like a dream with no overheating problems on the bench - it even runs nicely on one cylinder if you cut power to one of the ignition units! Obviously the challenge will be keeping it cool in the cowl of the Topflite P-51 it's destined for, but we think that is achieveable, With other ongoing projects though it is unlikely to maiden this year. Edited By MattyB on 14/04/2017 22:23:41

All my larger planes have voltage telemetry, I use multiple timers and I have a fairly consistent flying style with each plane, so yes my batteries do almost always come down between 3.75-3.85V/cell on all but the coldest days. Even if they don't I always stick them on a storage and balance programme on my discharge rig when arriving home anyway. That means they are always going to be starting from a very consistent starting point for parallel charging, though I still always double check cell voltages before initiating the charge. If any are too low for paralleling they get a few mins on the charger individually to even them up ready to go parallel. Many would consider this overly fastidious, but if you have a high powered dual output charger and a decent discharge rig it is no hassle at all. I can charge everything I need for an afternoons flying in less than an hour and have everything back at storage 30 mins after arriving home even with my biggest 6S batteries; as a result my packs seem to last far longer than people I know who a less rigorous routine. YMMV. Edited By MattyB on 13/04/2017 20:14:17

Posted by Bryan Anderson 1 on 13/04/2017 14:51:52: I wish you luck but it is not a good idea to connect balance plugs in parallel. If you have a bad cell or one more discharged that one in parallel with it then the current that flows to try to instantaneously balance them can burn out the tracks on the circuit board and/or the balance wires. I would not do this. Parallel charge without using the balance connectors and do separate balance charges every so often instead. Sorry, but I totally disagree. Crucial safety features within modern chargers rely on being able to see the voltages through the balance plug, and you are far more likely to end up with a pack or packs with unbalanced cells, one or more of which could be over 4.2V/cell. There is far more to lose by not connecting the balance lead than there is to gain. All that is required is to check the cell voltages of all the packs you intend to parallel charge first to validate they are all at roughly the same SOC (within ~0.1V/cell of each other); it takes a few seconds. If they are equal you are good to go. I and many others have done thosands of chages this way without issue. If it is so dangerous, why do the parallel boards come with balance plugs ports at all? Edited By MattyB on 13/04/2017 17:39:21

Posted by Bob Cotsford on 13/04/2017 10:52:19: "Basically we are at an inflection point - what we have known as "the hobby" is going to change massively in the next 10-15 years in terms of the participants, the types of craft they fly and for what purpose. Fighting or lamenting this is IMO pointless - it will happen over time whether you like it or not, so it's probably best to just immerse yourself in the bit of the hobby you enjoy and dabble in something new occasionally too; you never know, you might like it..." Seems to me we've been at 'an inflection point' for as long as I can remember and the hobby has been changing constantly for at least the last 50 years. Carrier wave, super-het., reeds, proportional, silencers - 40 years ago companies such as Jim Davies were flogging pre-built models, early ARTFs! Agreed, but I would argue the combination of huge technological change, potentially significant regulatory change and a major demographic change on the horizon amongst the traditional modelling community is an unprecedented combination.

Yes, I believe traditional balsa building is to all intents and purposes dead and will never come back, not even if the cost of ARTFs rise. The stark reality is that the majority of traditional builders are in the older demographic, and many are either deciding they prefer the simplicity of ARTFs or are giving up the hobby, especially with additional legislation potentially looming. Younger people like myself simply don't have the time and space to build with young families and busy jobs, and there are lots of alternative ways to spend the small amount of free time we do have that have lower barriers to entry (and I say this as someone who learnt to build with my Dad and still enjoy it). Flying fields are more difficult to get and keep and local shops that can supply the materials to build are thin on the ground. Finally (love em or loathe em) there are compelling alternative options to the traditional stick and tissue planes that weren't around 5 years ago (especially the compact, affordable FPV multirotors) - they require less space to fly and are more exciting to a younger generation. It is not all doom and gloom though. Building / construction is still happening, it is just not being done in balsa. Electric powered foamboard and depron planes are getting pretty popular, and there is a huge amount of home brewed innovation going on in multirotors, especially the racers and micro FPV platforms. 3D printing and open source software is also revolutionising the level of tech that can be put in modellers hands at very low price points. You can even have a "kit" laser cut to order from your own plan if you want; that feels like the most promising pathway for traditional builders to me moving fwd. Basically we are at an inflection point - what we have known as "the hobby" is going to change massively in the next 10-15 years in terms of the participants, the types of craft they fly and for what purpose. Fighting or lamenting this is IMO pointless - it will happen over time whether you like it or not, so it's probably best to just immerse yourself in the bit of the hobby you enjoy and dabble in something new occasionally too; you never know, you might like it...! Edited By MattyB on 13/04/2017 10:48:41

Agree with everything posted above. It used to be that buying a Horizon Hobby product meant you paid more but if something went wrong exemplary service was available to sort the issue. Now though that seems to be disappearing as they have recently closed their UK service/support, plus prices seem to be going even higher too. Pretty much any other brand would be a better choice at this point!

Posted by David Tayler on 11/04/2017 08:59:44: Thank you all for very useful comments. Derek is reviewing the HT lead,which he admits was a bit iffy, and I am making some inductors on ferrite beads to go in the aeleron leads.The size of the servos is under review although the plane has flown well for a few years on the 9g servos,I guess that my friend Derek flies it gently in a scale manner.I will post the outcome to the forum when we have sorted it. Many Thanks,David What size and weight is the model, and what engine does it use? This will help us to recommend the right servos, at the moment everyone is having to guess because we don't know these parameters.

Putting aside the fact that no micro plastic geared servo is the correct choice for a petrol powered Tiger Moth, two additional points for the OP: As per other posters above, the "jumping" behaviour you describe is most likely ignition related. Check the connection at the ignition unit and the particularly at the plug cap to ensure RF emissions from the ignition are minimised. HS-81s are plain bearing servos. That means they start off accurate enough, but in a relatively short amount of time get sloppy and start to double centre. This is an effect I have seen on all the 81s I have used in slope soarers, so I suspect the effect will be exacerbated by the vibration of an IC engine, especially a petrol single cylinder.

Posted by Steve J on 10/04/2017 19:43:35: Posted by MattyB on 10/04/2017 16:17:43: I have no idea whether they are true or not, but there have been rumours circulating for a while that HH have money troubles. Source? Hopefully not rcmodelreviews again. Nothing with any decent provenance, just rumours on RCGroups, hence why I stated "I have no idea whether they are true or not". I did talk to a model trader recently though who will remain nameless; he deals (maybe now that should be dealt...) with HH regularly. When I asked him about the company he simply shook his head and remained silent. PS - Congratulations on your promotion to forum moderator. Will you be giving warnings and points for those whose sources you don't agree with in future? Edited By MattyB on 11/04/2017 00:21:09

Posted by Steve Houghton 1 on 10/04/2017 16:17:21: I think this is a " how long is a piece of string" question. I have gliders, up to 3m that are rudder/elevator only, (Bird of Time), and I have never had any issues with not having flaps or spoilers. You just need to allow for a long approach on landing. I also have a 3m F5J full house model, and in still air, even with full crow, it can be a handful to get onto the deck as there can be little wind resistance on the flaps/ailerons to slow it down. And then I find I can sometimes get caught in ground effect, so it still just wants to keep going on forever. Of course, if you have a bit of a breeze against it, that helps greatly. The models the OP is looking at are a lot more like your F5J than they are a lightly loaded, comparatively draggy old timer like a BoT.

Posted by Justin K. on 10/04/2017 16:44:55: Posted by MattyB on 10/04/2017 16:17:43: Posted by Devcon1 on 10/04/2017 12:39:31: It read a bit like this one a while back. Do I see dark clouds looming over the Horizon ? I have no idea whether they are true or not, but there have been rumours circulating for a while that HH have money troubles. Certainly these changes look to be an effort to cut costs; they will probably be successful in that respect, but the prospect for sales is less clear. I struggle to believe any potential buyer would be enthused to move to Spektrum or buy into HH products in general once they were aware of these changes. Do you mean buyer of equipment or a company buyout Matt? Sorry, lazy words. I meant a customer purchasing their products. I have seen no information suggesting there is a sale of the company is in the offing. Edited By MattyB on 10/04/2017 17:51:41

Posted by Devcon1 on 10/04/2017 12:39:31: It read a bit like this one a while back. Do I see dark clouds looming over the Horizon ? I have no idea whether they are true or not, but there have been rumours circulating for a while that HH have money troubles. Certainly these changes look to be an effort to cut costs; they will probably be successful in that respect, but the prospect for sales is less clear. I struggle to believe any potential buyer would be enthused to move to Spektrum or buy into HH products in general once they were aware of these changes.

Clever stuff, but all that sewing is not particularly enticing... I could see a market for these as an affordable PNP/BNF offering though by one of the "big box" manufacturers. They would be very attractive if set up as a slow and stable FPV platform with a pan an tilt system, though I suppose camera stability might be an issue.

Just checked, must be a Flash website... Works fine on a PC, here's the relevant page (Radian Pro SPM download from the button in the middle; don't ask me how to get it on your radio though, I don't use Spek).

He has posted a demo SPM file somewhere too, but it no longer seems to be on RCGroups. Try the Spek downloads website maybe (though the buttons seem dead on iOS devices).

Hmm, ok. Not an ideal radio for sailplanes, but with the update they added in 2013 a passable if slightly compromised setup is possible. These resources should help: DX8 sailplane programming thread, RCGroups (use "Search this thread" function to find answers to specific questions) Sherman Knight's (HH pilot) sailplane setup guide v2 Sailplane setup walk through Edited By MattyB on 09/04/2017 19:40:59

Post deleted, looks like you got there... Edited By MattyB on 09/04/2017 18:22:15

Good decision. What radio do you have Steve? We may be able to help you with a suitable 4 servo wing setup. If you have an OpenTX based set (9X, 9XR, Taranis or Horus) I highly recommend Mike Shellim's setups; he has one that is dedicated for e-soaring use and is fully documented.

Piers makes a good point. I am comfortable with thermal models up to ~2m having no braking mechanism (spoilerons are generally enough to get you out of a boomer), but would not want to go above that size without at least spoilers and ideally crow. With skill and experience it's possible to escape even with only r/e control, but if you are new to big gliders having that additional ability to increase your descent rate dramatically without overstressing the airframe may enable you to avoid a total loss. Edited By MattyB on 08/04/2017 20:17:30

What radio do you have? If it is capable of driving a full house 4 servo wing setup (i.e. flaps, crow brakes, snap-flap and quattro flap) I would recommend you go for the flapped version. Yes it will be more complex to setup initially, but it gives you loads more options to improve performance and land on the spot. It will also help teach you the true capabilities of your radio which may help improve your setups on other models.