Marc Humphries

Posted by eric loakes on 17/08/2010 12:57:58: I miss flying my Funcub;it's so relaxing.   But as I reported ealier, my Instructor does not want me to fly it whilst I'm training with an I/C model.  Especially as I'm getting close to my "A" test.    The field I'm training in has obstructions, such as hedges and trees, which have to be negotated.     With the Funcub I'm able to stay within the confines of the Field.  Eric.   Do what?  Being told not to fly one of your planes?  Never heard of that before...   I'll add that to my growing list of "Why I seldom fly at a club".

 David's right - still catches me out even now.

Steve,   Everyone who says get brushless EG, or convert yours to brushless is ultimately right.   BUT...   I've had a stock brushed EG for three years.  If you want to go gliding and catch thermals - you need nothing more. So what if the climb, to say 200 metres, takes a minute or two?  What advantage will getting there in 30 seconds have in the context of a 40 minute thermal soaring flight?   I use a 2200 2S LiPo and in still evening air regularly get flightsover 45 minute . When there's lift about - you will be more worried about getting the thing down than how quickly it got to launch height.  Have a look at this thread here for some of my EG exploits.   Enjoy EG for what it is - a glider with motor assisted launch.  If you want "hotliner" or  "warmliner" performance - there are other models on the market - Blizzard, Blaze etc.   CheersEdited By Marc Humphries on 23/08/2010 11:36:00

Mmmm...   All of this is very interesting - and reminds me why I very seldom fly with a club these days.

On two occasions this month I have been blown away by the generosity of two forum members.   My first plea was for a Formosa canopy.  Lee Smalley very kindly scrambled around his wokshop and sent me one free of charge and refused to even let me refund his postage.   Second up was Brain Lambert.  I had a real anorak moment and wanted to get hold of a 2007 BBC 4 programme "Marcus Brigstocke's Trophy People" where he spent the weekend with F3A flyers at the Nats.  Next day a DVD copy from Brain's hard disk arrived - complete with jewel case and colour printed label.  Once again, Brian did not accept my offer of a blank DVD and postage refund.   Thanks guys - you are real diamonds!

There's a video here - scroll to the bottom of the page.   Certainly doesn't look sluggish...

@David I agree - they fiddle just for the sake of it!  They put 600 W motors in glass covered Formosas - why?   Remember, a twin engine bomber is not going to tear around the sky like a P38.  My experience with twins (not scale) is that 70 - 80 watts per pound is fine and gives a good scale like peformance.  To give some calibration - a brushed Twinstar with a 7 cell NiMh gives around 50 Watts per pound.   Even the huge Boeing B-50 that TN designed works out around these figures - or even less.   As Lord Percy would say, "Fly the thing Edmund and be damned with it!"

Brian!  What can I say!   Just as I was giving up all hope...   Marc

Hi folks.   Missed the original transmission and the 4 repeats (last on was in 2009).   Did anyone record it on hard disk or  DVD?  If so - I'm looking to pay for a copy.  Will provide the DVD and pay for postage.   CheersEdited By Marc Humphries on 16/08/2010 23:28:02

Thing is with an EDF you will not have the ability to play around with the prop size (and to some extent the motor kV) to adjust the current at full throttle.  So upping to 4S will increase the current - so you will get less flight time from both the 2200 size and especially 1800s.  You will get more performance - but you will also increase the current consumption.   The argument for increasing the pack size comes into it's own for much larger power set ups - say over  750 - 1,000 watts.  Here, 6S or 8S packs enable current consumption to be a sensible 40 - 50 A, but this can still deliver up to 1.5kW. With a prop driven aircraft, you have much more flexibility with the motor and prop combinations to achieve this.   Marc  

Freshly charged - an 8 cell pack will show over 12 volts with no load.   Under load - you should be looking at 8 - 9 volts or so.  Current should be around 10 Amps max.   See what reading you get with your Fluke and clamp meter.Edited By Marc Humphries on 10/08/2010 18:59:57

Depending on use and abuse - brushed motors suffer from armature and brush wear.  How many flying hours has it had?   Is it geared or direct drive? 9.6v through a 380 (rated at 6.0v or 7.2v) eventually takes it toll.   Alternatively - your battery may be playing up.  Check it out under load on a Watt Meter if you have one.   Cheers

Hi RW,   Here's my experience - based on the Formosa and not a GWS warbird.   I initially used the stock 350 geared motor with 800mAh and 1000Mah 2S LiPos with the stock prop.  Performance was good - but gentle.  It could loop from level flight, but vertical perfromance was limited, and the model had to be flown in calm conditions.  I think you will find that a 2S LiPo will give a better performance than a 7 cell NiMh, because as you say the voltage holds up better under load.   I then put in the brushless motor with a 7 x 6 prop - with the same 2S LiPos.  Performance was more sprightly and surprisingly long at around 9 minutes or so.   BUT...   If you can squeeze in a 3S - even if it is only 1000 mAh - then you will be rewarded with excellent performance.  I use 1500 Zippy packs, which gives the combo around 160 Watts with a 7 x 6 prop and up to 15 mins duration with mixed throttle flying.  I can normally get three vertical rolls from this set up and is good in winds up to 15 mph.   On calm days - I squeeze in a 2200 2S LiPo from my Easy Glider and can fly for ages - but not with the same zip.   Regards,   Marc

Howdy.   Try this from BRC. BRC Combo   I use this in a GWS Formosa with great results - I like the fact you can still use the stick mount.  Gives about 160 watts on a decent 3S LiPo with a 7 x 6 prop.   Marc

Jeez - appaling spelling on the thread title.   Should be "four" and "NiMh"...

Dropped my fresh of the charger 3300 NiMh pack onto the garage floor last night.   Landed on the edge of one of the cells- instant smoke, mild glowing etc.  At least only one cell fried...   Oh well, this has accelerated my purchase of a couple of  kick ass capacity LiPo packs for my brushless TwinStar conversion.Edited By Marc Humphries on 09/08/2010 10:38:57

I would love to write an article about the whole supply chain and value stream of how ARTFs are put together.  Think BBC3 "Blood Sweat and Luxuries" - but for model planes.   As a business consultant I'm only to aware of off-shoring and global sourcing and that it's been a game changer for our pursuit of flying toy aeroplanes.   What do you think?  Any interest?  Will the Ashbys cough up a ticket to China and Vietnam?

Christian,   As a serving officer - don't you have a batman do that sort of thing?  

@Christian I know exactly what you mean.  A Sleek Streak was what I aspired to.  Someone at school then got one of those plastic ready made control line planes made by Cox.  He was treated like royalty from half the kids - while the other half wanted to beat him up!  Such is life...  Are you a Premier League football star? How else are you earning £60,000 per week. @Bob Five to ten years ago I would have agreed with you.  In the centre of Northampton is a very large park called The Racecourse.  As kids in the 70s we'd go along on a Sunday morning and watch the 15 or so local club fliers.  Amongst the local league football games, large 60 powered planes would take off and beat up the sky.  Can you imagine that now? But for me, electric power has changed everything.  I am lucky to have several playing fields and an agreement with a tenant farmer who farms council owned land all within a three minute drive.  It has transformed my flying. Edited By Marc Humphries on 06/08/2010 09:54:59 Edited By Marc Humphries on 06/08/2010 09:55:49

Gonzo,   It does probably use RPI - as this gives a more consistent and validated result.   Interesting your comparing BT Technical Officer salaries and your bench mark.  Dangerous - as we all new we were overpaid - I was one for 10 years before I was promoted and then left the company after 16 years.  I remember getting pay rises of over 20% in the late 70s and early 80s.  Compare and contrast  with the fortunes of others.   Anyways - we could argue about the actual numbers the calculator turns up.  What it does prove beyond any doubt is that aero modelling now has never been more affordable.   Cheers,   Marc

I obviously have too much time on my hands - but the 50th anniversary edition with its collection of adverts through the ages got me thinking what the real cost of these items would be in today's terms.   Found this neat inflation calculator on the web that is very easy to use and gives some interesting results:   1975 Futaba standard servo £11.  2010 equivalent £84!   1965 RCS 10 channel Tx and Rx £68. 2010 equivalent £1,103   1970 KK Elmira glider kit  £6 19s 6d.  2010 equivalent £120   I guess some values survive better.  The Elmira glider kit would still be reasonable value for money if now laser cut (compare with DB models stuff).   The RCS combo was cutting edge - so not so far away from a high spec Tx these days - but think of the huge gulf in terms of capability and functionality.   But wow!  That servo price!  No wonder we only ever had four of them that were transferred between models.  What is now a near consumable item was a significant investment.  One last one - as it's due to make a comeback:   1975 Gangster 63 kit £22.95.  2010 equivalent £175.80.   Let's see what price the ARTF version hits the shops at.Edited By Marc Humphries on 05/08/2010 10:38:07

...Oh - you can also download a simulator as well!

Me?  Started life as a telephone engineer (technician?) with PO Telephones.  Did HND and Degree in electronics and telephony.   "A ops B, B ops C - then the switch goes ro-tary"   Unless you worked on Strowger exchanges - the last line will mean jack to you...   Moved into learning and development, e-learning, multimedia and now business consultancy.  Thing is though, once an engineer - always an engineer.  I bore the pants off my colleagues with business and human science degree backgrounds when I talk about how things work.   My soap box rant is about people using terms like "Amperage" when they mean "Current" - and the general trend to state opinions as facts on many forum posts...

Steady on Ackers - that soap box is wobbling...

Found a great presentation Albatross and Dynamic Soaring that explains everything you wanted to know about Dynamic Soaring but just couldn't be bothered to, well, find out.   This always sparks debate when Andy Ellison updates us about the latest DS glider world record and usually results in total confusion.   Enjoy!