MattyB
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Posts posted by MattyB
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Posted by flight1 on 09/05/2017 18:12:51:
The problem you might have is you are using a 4 cell battery pack and the plane requires a 6s battery, you could always use two 3s packs in parallel to get the 6 s as its far more cost effective
Errr no, that's wrong on two counts....
- There is no way of knowing from the OP if the model is intended for 6S operation - he has not included enough detail. Throwing a 6S battery at it without understanding the specs of the powertrain is likely to end in tears. If his current drain is already high it is only going to get (dramatically) higher on 6S with the same prop.
- 2x 3S packs in parallel is still a 3S pack, but with twice the capacity i.e. 2x 3S 2200 in parallel = 1x 3s 4400. To get a 6S pack you would need to connect them in series, but they then still have the same capacity as labelled i.e. 2x 3S 2200s in series = 1x 6S 2200.
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Posted by ericrw on 09/05/2017 18:00:17:
My FMS Mustang flies with a four bladed 16x6 prop and a wingspan of 1600mm. However, there is a huge drain on the 4 cell 3700 battery. To overcome this problem, I have been advised to use a two bladed or a three bladed prop. Could anyone on the forum, advise me of what size to go for with either a two or three bladed prop ? Appreciate any advise !!
FMS do not make a 1600mm Mustang to my knowledge - lots of 1400s and definitely some 1700s (though I am not sure they are still available), but no 1600s. That means it may be a Starmax, or you may have the span wrong in your OP.
Either way we need more precise details of model and motor specs (especially the Kv) to make a recommendation. However it is now pretty standard to re-motor and change the prop on the 1400mm foamie warbirds for 6S operation; they are all a bit undercooked on 4S. If you go to RCGroups and search there on "6S [manufacturer name] mustang conversion" you should get lots of hits recommending powertrain components.
Posted by ericrw on 10/05/2017 09:16:12:I`ll try two 3cell batteries; but is it possible that faulty ESC could have an effect on the power drain ?
It is highly unlikely the ESC has anything to do with your problem - remember it is the motor and prop specs that define the current draw, not the ESC.
Do not go 6S (2x 3S in series) without doing some calculations and understanding what the current draw will be first; if you do your current will increase dramatically (probably around 2x given the dramatic increase in voltage) and it is almost certain you will cook the ESC and probably the motor too. You have to apply science and maths not guesswork if you don't want to fry components - time to do some reading on how electric powertrains work.
Edited By MattyB on 10/05/2017 10:54:14
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You want big, fine pitch props for 3D where thrust is more important than speed. Without specs on the model though (span, weight etc) it is impossible for us to recommend a motor.
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Posted by Steve J on 09/05/2017 18:41:27:
@MattyB Open class subcategory A3 means that you don't have to be a member of an association or club to fly models below 400ft. All that you have to do is register, do some online training, an online test and fly away from uninvolved third parties (UAS.OPEN.60).
Right, but how do I do that at 99% of slope sites? These locations are public access; they have to be for us to get there to use them. That means there is always a decent chance of the public turning up; indeed many of the best slope sites are well known viewing points, and therefore destinations for walkers and the general public.
My home slope at Ivinghoe is a good example - it will undoubtedly need an OA as there are hundreds of walkers a day in good weather. That should not be an issue for us given we have a longstanding club with a good safety record, but many other well loved slope sites do not have a club overseeing them. What of them? Are we back at the idea I floated a few months ago of a UK wide soaring association to document and oversee these sites (link)?
Edited By MattyB on 09/05/2017 19:38:30
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Posted by Steve J on 09/05/2017 16:10:23:Posted by Biggles' Elder Brother - Moderator on 09/05/2017 13:13:58:
EASA's plan to achieve this (whilst still allowing model flying) is to concentrate all model flying at a relatively small number of well documented sites.
Citation needed.
Steve
Having read the document most of the way through now I concede I can't honestly tell what their intention is.
Ostensibly safety is a priority, but being cynically minded I started from a position similar to BEB's that this is mostly about freeing up airspace below 500ft for commercial gain and increased tax revenues. If EASA were to do that in line with Amazon's vision I am quite sure we would be limited only to defined sites, which could effectively mean the end of legal slope soaring in locations where there is no resident club or "official" history of RC usage. Even so, I can see that (even if that is the intention) there is potential to escape some of the most onerous requirements depending on how the document is implemented within a member state.
As currently worded it all seems to hinge on who the competent authority is (i.e. the CAA or BMFA) and the exact nature of the powers they can delegate/operational authorisations they can grant to clubs or associations. For example:
- If the competent authority is the CAA, can they grant OAs to BMFA/LMA members as a group (club and country members), or only specific clubs in defined locations?
- What requirements can be negotiated out under and OA, and what can't? Registration - presumably not? Height limit - presumably yes, but under what conditions?
I guess we will find out over time, but it seems like this is very high level stuff and there is a long way to go before sufficient detail is added to enable us to understand the end state. It does look slightly better than draft 1, but my underlying concern remains that big players like Google and Amazon lobby hard to reduce or eliminate the powers of CAs to delegate authority and implement this differently across individual countries. If that occurs the very small number of modellers EU wide (from an electoral standpoint at least) stand little chance of coming out on the winning side against the big money.
Edited By MattyB on 09/05/2017 18:06:27
Edited By MattyB on 09/05/2017 18:10:13
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Google and ye shall find...
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I am a little surprised there is nothing on the BMFA news pages regarding this latest document from EASA. Given they have been intimately involved in its creation I would have thought a communication would have been ready to go up the moment it came out? I am very interested to hear whether it will publicised as major improvement or a disappointment compared to v1 that they were not very complimentary about...
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Maybe you need to ballast it for high winds like a sloper...
PS - When converting 109lbs to kg (yup, I'm a child of the metric age) Google helpfully informed me that this model r model weighs exactly the same as one of the worlds most untalented celebrities...!
Edited By MattyB on 08/05/2017 23:11:41
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On a different topic I was quite surprised how much this model got thrown about in the wind considering it's large size. I guess it is probably quite lightly loaded and obviously it's very draggy with a lot of front and side area. Certainly looked a bit of a handful on landing, especially the second flight.
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Posted by ERIC CLAPHAM on 08/05/2017 13:28:57:
Finale - A free plan in the April.88 Radio Modeller by Mike Freeman. The control movements are given as (both pitch and roll) 3/8 -5/8" at the wing root trailing edge. Original weight 18oz. C.G. at 2.75" from the root L.E. i.e. about 0.35" in front of the wing pivot. He had another more orthodox layout plan but still with wing twist, as a
Interesting. I would say 5/8" aileron movement would really be a lot for a model like this - you may want to set up dual or variable rates on pot (if your TX can do that) to give you a better chance of success. Another alternative is to "fly" the model in your hand on the slope edge whilst having someone else move the controls to get a feeling for how much effect they are having.
Edited By MattyB on 08/05/2017 17:55:09
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Yes, HS81s are IMO not a good choice - the plain bearing develops slop over the flights and eventually they all double centre. The 85s do not suffer this, though to be honest any decent mini with a ball bearing on the output shaft should be fine.
Edited By MattyB on 08/05/2017 17:44:41
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Edited By MattyB on 08/05/2017 17:41:02
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Definitely 1 per wing is preferable, but 9g nylon gear servos are two small IMO for an IC of this size - the gear area just isn't big enough to cope with the vibration over long periods. Fit a bigger (15-25g) metal geared alternative and you will be fine - HS85MG or similar should be fine.
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No idea what it is, but assuming it's a pitcheron (which looks the case from the pic) it will need as much pitch movement as you can get, and very little roll - 5mm or so should be fine.
Edited By MattyB on 07/05/2017 16:19:16
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Posted by Simon Chaddock on 06/05/2017 11:29:15:
I really don't follow the logic on how generating a lower wattage by using a lower kV motor can increase the stress on a battery.
Surely less watts means less amps and its amps that stresses a battery.
Sorry, my original post was not that clear I admit. What I was trying to say was that the only other option if he doesn't change the motor is to go 3S and prop up to get the desired wattage. That should work, but pulling 600W out of a 3S setup is going to mean drawing 55-60A from his packs, a substantial increase in current draw over his existing 4S setup even though the maximum wattage on 3S will be lower.
Edited By MattyB on 06/05/2017 14:11:21
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Posted by Steve J on 06/05/2017 09:28:09:Posted by Andy Symons - BMFA on 05/05/2017 11:37:52:
Day pass for flying is £6.
Has the BMFA published an estimate for the annual running costs of the NFC? I am curious as to how many £6 day passes it would take to cover it.
Steve
No, but based on the limited figures they have released it is possible to make an estimate. Some rough calculations I posted in the main NFC thread...
- The BMFA are investing £335k within the first four year term of the lease (figures in this presentation). Lease costs are £18k in year 1, £27.4k year 2 onwards.
- You can probably add at least another £20-25k per annum to that for grass cutting, security, amenity charges etc (that is the only key figure they have missed out of their deck), so to stand still the project will have to generate revenues of ~£45-50k per annum at a minimum to be self funding. More than that will be needed if the proposed additional facilities are to be added.
Edited By MattyB on 06/05/2017 13:47:19
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You are unlikely have any short term problems limiting max throttle via an endpoint, but depending on the type of ESC you could cause an early death to the FETS which are working harder at part throttle than full. Adding an extra heat sink to improve cooling might help with that though.
Ultimately you'd improve the whole setup with a lower Kv motor of the same size and weight - you could then turn bigger props that give more thrust at lower rpm, reducing noise and probably increasing duration too. Your only other option is to try 3S and bigger props, but you may need a larger esc and will be stressing your batteries more to generate a lower wattage.
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The requirements to be a competent authority appear significant and complex (registration of operators and UAs, audit and oversight of operators, granting and oversight of the operational authorisations etc.). That is far more than the BMFA and LMA do now to oversee their members. IMO they will need a fair bit more manpower and far more advanced IT systems to do the job. Meeting those requirements is not going to be cheap or simple for the BMFA.
Also worrying are the additional requirements on clubs to provide training and oversight of members. It is hard enough to get volunteers for committee positions as it is without all this red tape and a potential threat of being held liable if your paperwork or oversight procedures are deemed insufficient. This could really affect (legal) participation the hobby very significantly.
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Nobody at the BMFA has stated that to my knowledge Phil. It is nowhere near big enough to run the power Nationals in their current format, but if they were prepared to split up the disciplines over a number of w/es it could be made to work if Barkston was unavailable. Would it attract the same audience if that was the case though?
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Hmmm, plenty of nasties still in there - looks like registration of operators and models for the vast majority of us, 120m height limitations and the addition of technical height limiters and geofencing in certain situations.
I've not been able to get to the bit where exceptions granted by overseeing authorities are detailed. However it's obvious that (as many suspected) users of public sites are going to have major issues unless their model is below 250g. Slope soaring in particular looks difficult to do legally given the expectation (pg15) that traditional models >250g can only be flown "...in an area where it is reasonably expected that no uninvolved person will be present". In addition privately built models in without all the fancy tech can only be flown "a safe distance from the boundaries of congested areas of cities, towns or settlements, or aerodromes" . Fly anywhere near an uninvolved person with a model between 900g and 4kg and you need geofencing - how the heck does that work on an unpowered glider!
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Posted by John F on 05/05/2017 15:06:01:
You said this, Matty, with regards to the initial efforts too! Can we not turn it into yet another MattyB opposition thread with yet more predictions of doom and gloom?
Many people are perfectly happy with what they are doing and are quite happy to support this.
Alternative viewpoint... Can we not turn it into yet another blind optimism thread with yet more predictions of a green and pleasant land despite the fact there is no funding plan beyond the use of £335k of reserves (60% of the Dev fund) to complete phase 1?
Many people are uncertain about the financials and uncomfortable with how the project was given the green light. They are unlikely to support the significant fund raising efforts needed until they see a clear plan for phase 2 and beyond from the BMFA showing how the money will be raised to turn it into a true NFC.
Seriously, last time I looked this is a free country. If you believe my post is against the CoC, please go ahead and report it. If not, leave it to the moderators.
Edited By MattyB on 05/05/2017 16:36:39
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As long as the charger is firmware upgradeable for other new battery chemistries I would not worry about it. Personally I have seen no reason to move to the LiHV batteries as unless you are involved in very demanding e-flight disciplines their benefits are negligible; there are likely to be negatives as well (charging to higher voltages must increase the speed of anode degradation, causing earlier capacity loss and higher IR).
elevator unresponsive
in All Things Model Flying
Posted
"ain't designed for power dives"
That would be my take on a foamy. At high speed it only takes the tail plane to flex under the load of the deflected elevator and the net result is no 'elevator' effect at all or even control reversal.
That is somewhat of a sweeping statement - sure there are some floppy foamies, but models like the EFX, EFXtra, Roc Hobby pylon series and the Mpx Dogfighter are well reinforced and good to >100mph in stock form, more with a few mods. Horses for courses.
My gut feel is that the OPs issue in this instance is most likely to be CG related, but if worried about flex check the linkage run thoroughly, upgrade the servo ff needed, check the elevator horn is solid and reinforce the elevator itself with a few pieces of inset carbon strip and CA.
Edited By MattyB on 10/05/2017 11:32:35