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Member postings for Cuban8

Here is a list of all the postings Cuban8 has made in our forums. Click on a thread name to jump to the thread.

Thread: Prop size and efficiency
19/08/2019 15:09:57

You can really tie yourself up in knots with this, so I like to keep things fairly simple but with an eye to the fact that the subject is far from simple!

Through trial and error (but with test equipment -wattmeter and electronic fishing scales) I have found that for sport type or club aerobatic 'planes, initially designing for a prop towards the larger size range of what's practical is a good place to start. I then aim for suitable static thrust/rpm/current/voltage depending on what I'm after and select components to suit. The APC website gives useful prop info and there's some excellent performance preditor websites where prop size and RPM can be plugged in to give expected static thrust and power figures. Given all the possible variables, they're usually good to better than 15% of real world performance - which isn't bad and gives a bit of 'tweaking room'.

Cell count/motor Kv/ power can then be juggled around to match what your after or what's parts are available from suppliers.




Edited By Cuban8 on 19/08/2019 15:19:06

19/08/2019 10:12:11

Interesting data - I can only comment that when designing an electric installation and taking into account the model and its expected performance envelope, I always start with the largest diameter propeller that will give adequate ground clearance for a conventional tractor arrangement. Compromises may need to made for pushers. Another benefit is that the model will be much quieter with a larger and slower prop.

Thread: Revolver Pusher type Autogyro trainer
17/08/2019 06:27:44

Very encouraging, many thanks.yes

16/08/2019 16:25:57

Just had a cuppa to go over this and I think I made a mistake first time round with transposing the GC string position. I'm using a separate plumb line secured from the same point as the string that's suspending the model and for the second setting I didn't align it correctly with the string supporting the model from the nose leg. This time my CG is about 15mm below the thrust line, so much better. How close do I need to get it? Should I trim the prop to allow me to lower the motor?

Learning something new every day with Autogyros................

16/08/2019 15:39:44

Everything going quite well, model fully assembled and all gear/battery in place. Carried out the hang check and it worked out right down the middle of the suggested range at a tad over 16 degrees. Followed the article's instructions and moved on to the vertical CG (suspended from the nose wheel leg) and marked on the airframe as instructed.

Previously, the motor was temporarily fixed to give 10mm prop clearance to the tail boom (9x6 two blader) and the thrust line is a good 25mm above the rearward projected CG position. - blue dot in yellow square. Seems excessive given Richard's remarks about importance of thrust line and CG setting in the mag article.

Not sure how to proceed.sad20190816_151530.jpg

Thread: AR620 Power up issue
16/08/2019 07:27:13

Diagram is exactly as I expected & looks fine. Where you say 'signal wire only' presumably you mean the +ve ESC BEC supply is disconnected, leaving you with two conductors in the plug i.e signal and 0V into the throttle port (from which the RX would usually get its power from a BEC/ESC). Common ground running through the components, so shouldn't matter.

Have you tried removing the external BEC supply from the RX's battery port and supplying the RX via a spare servo port instead? These are normally all part of a single 'bus' common to all the servo connectors at the side of the RX, but there's something strange about the 620.



Edited By Cuban8 on 16/08/2019 07:40:33

15/08/2019 17:17:35

Just checking.....

1 Does the 620 work as it should when just powered from the separate CC BEC and Lipo?

2 Does it work correctly when powered from the Lipo/ ESC BEC but without the safety switch?

3 Does it work correctly when all connected up but without the RX connection to the ESC?

If the BEC is powered from the input of the safety switch i.e. in parallel with it - can't see how the BEC's Lipo supply would be affected.

Something funny going on here.............bit like one of those IQ test questionswinklaugh

Any chance of a photo of the wiring? Gotta be something simple.


Edited By Cuban8 on 15/08/2019 17:33:04

Thread: Drones in the news - again...
15/08/2019 10:54:41

I suppose the 2 mile restriction zone was imposed to emphasise the necessity to have no UAVs operating at or close to the event, but as has been said, existing restrictions covering UAVs at events/congested areas etc etc would have curtailed any flying anyway. I wonder if any other drones were flown but not apprehended - anything appeared on YouTube?

15/08/2019 10:09:12

Goes to show and should be quite clear to any reasonable person that the current laws covering UAVs are effective when enforced, and given the exposure via the news media and official sources, very few people will have an excuse claiming "we didn't know the law". Unfortunately, legislation and rules encompassing even the most draconian restrictions will never stop those hell bent on doing their own thing. The sensible and law abiding majority losing out to the minority lunatic fringe once again.

Makes registration and all the rest of it a complete and utter waste of time and money.

Thread: 4 stroking a Merco...
14/08/2019 11:17:28

Don't be put off by the few problems some have encountered on BMFA Classifieds. Buying second hand is always a risk, but providing you take reasonable precautions, (biggest is always use full PayPal and NEVER PayPal Gift) trust your instinct and preferably have a talk with any prospective seller - you can then filter out the idiots selling junk.

Took me six months, but I bagged a NIB OS120FS (unpumped version) for £220 delivered.

I'm afraid swap meets can also be very risky, some good honest bargains are about, but equally, a hell of a lot of what's offered would be better off in a skip. Caveat emptor and all that.


Edited By Cuban8 on 14/08/2019 11:21:26

Thread: Commons Science and Technology Committee Enquiry on Drones
13/08/2019 16:29:18

I have absolutely no doubt that the BMFA officers who have been in at the sharp end of this are giving their all and will continue to do so with the best of intentions for a positive and just outcome for BMFA members and model flying in general.. As has been said, it's gone quiet of late, so 'no news is good news' or 'the lull before the storm' - take your pick.

Thread: Laser cut kit, how many of you sand off the brown laser scorching before gluing?
13/08/2019 15:50:56

On small parts or thinner sheet, I just wipe over the burnt surface with my thumb or finger to take off any loose excess and then glue as normal from there. I might wipe over with fine sand paper if the part is more substantial say 1/4 sheet. Experiments with scrap would suggest that even this is not really neccessary, makes me feel better to do it though. I don't use Aliphatic so can't comment on that adhesive, but no issues with cyano or PVA.

Thread: Commons Science and Technology Committee Enquiry on Drones
13/08/2019 12:01:36

I think we're some way off civil disobedience or shutting down government buildings. Not a path I'd like to see us take and one which will not happen anyway. Social media is a very powerful tool, but since BMFA's acceptance of drones on all of our behalfs, rather than leaving them to come under the remit of their own specialist body, there'd need to be quite a bit of back-pedaling - not going to happen - so much for the 'drone dividend' that has been much trumpeted as a saviour of the hobby. More like a poison chalice.

Like you, Michael, this fiasco has really got to me and needs to be pushed back to a review of its legality and fitness for purpose as it affects us, if it's finally pushed through unamended by rational discussion. Still a couple of months to go before D (drone wink) day, maybe BMFA can pull something out of the bag from their talks.

13/08/2019 09:18:56

The test and fee are a total red herring as far as we're concerned - don't forget that the free for all use of drones has prompted this, not hitherto, any urgent requirement for additional regulations on model flying. All model flying should have been given a blanket exemption whilst the effectiveness of drone registration etc is proven - which it never will be given the certainty of the regs being ignored by the majority of its target group and unenforceable anyway. The fantasy of having your consumer goods delivered by drone will also remain in the realms of the publicity stunt, so another nail in the coffin of regulation from that standpoint.

It's a rotten set of proposals set out by people who should know better. As for the £16.50 that so many are apparently happy to stump up - perhaps better use of resources will be to fund a legal review, or whatever would be most appropriate for our be properly explored, so the government's case for our regulation as proposed can be properly tested.




Edited By Cuban8 on 13/08/2019 09:31:28

12/08/2019 22:53:37

So the consensus is that we simply roll over and allow this travesty to take root?

12/08/2019 21:47:32

Perhaps a pertinent question is to ask whether BMFA's remit and/or scope includes litgitimising a quite useless piece of legislation that is in the process of being foisted, unjustly, on its members........,and in the full knowledge that what is being put into place will do nothing to solve 'the drone problem' either real or imagined.

If this nonsense does actually come to pass, presumably BMFA will only be interested in whether its members are operating legally for the purpose of validating members' insurance cover. Might BMFA clubs be delegated to check their members' registration status and subsequently declare conformity? How would anyone know whether a member was registered or not if they chose not to say or indeed lied about registering? Sounds like it could be a real can of worms.

Thread: CRRC 26cc - Plane suggestions
12/08/2019 11:41:04

Choice of model is only part of the equation, with reasonably priced glow motors now becoming increasingly unobtainable with the demise of ASP et al, the petrol option is one that many of the chaps I fly with are looking much more closely at. Not everyone wishes or has the wherewithal to pay the prices of the petrol four strokes that are around (as nice as they are) so something around the 1.20-1.80 glow equivalent and around the £250 or less mark would fit the bill, to say nothing of cleanliness and economy with petrol.

Noise is the big problem with inexpensive 'gas' motors and is still not addressed by the makers of these engines. The add-on silencer article in the current magazine is interesting and one of my flying buddies has ordered a couple of the silencers to see what can be done. Another has modified a DLE 20 silencer with the pot scourer trick and I have to say the engine is well acceptable. and actually has quite a pleasant tone to it.

I have some other ideas that might increase the effectiveness of the noisy standard petrol silencers and will share if anything comes of it.


Edited By Cuban8 on 12/08/2019 11:42:31

Thread: Silver Spitfire
11/08/2019 11:19:02

I've been trying to closely follow the Spit's progress, but their website and publicity seems very lacking in real time info.

Edited By Cuban8 on 11/08/2019 11:20:34

Thread: Electric Cars.
11/08/2019 11:14:04

I was up in Derbyshire when the lights when out for half an hour or so. I have a feeling that there's more to this than what's being served up as an extremely rare event blah, blah, blah.

Just two stations go down at a time where demand is nowhere near its maximum and the grid partly falls over putting millions without power albeit for a short time.

Thread: Interesting reply from email to Richard Moriarty, CAA
07/08/2019 16:38:11

I've made up my mind to never interfere with foolish / illegal drone users in public, any more than I'd be inclined to flag down a motorist who was contravening road law. In our situation, If the powers that be generate a load of tosh and then can't enforce it, that's their problem.

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