Recent Posts

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Sorry Al, if you would like to be CD for the day it could return to the 6th.
How's the Italian Citrin going  :)
Adrian
2
Bugger,
I had just booked my flights to Cyprus (grandkids to visit), nicley avoiding the 7th, so we leave on the 9th and return on the 14th.


and I would have flown REALLY well.


enjoy the comp


Al.
3
General Pattern Discussion / Re: Turbulator tape
« Last Post by Keith Jackson on Today at 10:32:15 am »
Hi Chaps,


The main interest I have is the same as Malcolm; to try to get the model to behave more predictably in turbulent air without having to resort to flying fast. I’m not sure if the turbulator tape will help; certainly the wing fences make a big difference in approaching the stall for spins. Yet to try these on the tailplanes yet but there are enough in use to suggest it does make a difference. Even BJ is taking this seriously as he’s releasing a wing/tail pack in 1mm carbon.


Keith

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Competition News / Hurley - National League - 13th October 2019
« Last Post by Adrian Harrison on Today at 09:17:54 am »

Due to unavoidable CD and judging commitments the final National League competition of the season will now take place on Sunday 13th October.
This is an unavoidable date change which I apologise for but hopefully those pilots who have already entered can make the date change,
Please let me know if this is a problem

This competition is open to all BMFA members holding a 'A'certificate.
All GBRCAA schedules and the FAI P19 + Masters A20  schedules will be flown.
Pilots briefing 8.45am first flight 9.00am.


FAI P19                                       
                                                                                     
Ross Donovan
Steve Burgess
Thomas David
Peter Jenkins
Dan Workman
Adrian Harrison



Masters

Greg Butterworth
Andy Shutt



Intermediate 

Mick Broad


Clubman

Dennis Lambe



Judges -  Bob Ailles.
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Ashbourne National League Competition Sunday 22nd August

All schedules will be flown and points gained will contribute to the National League standings.

Entries are welcomed from all BMFA members holding a current A certificate.

Entries particularly welcome from Clubman and Intermediate pilots

FAI P19

Keith Jackson
Thomas David
Adrian Harrison
Dan Workman
Gerhard Fehringer

Masters

Andy Shutt
Greg Butterworth
John Mattingley



Depending upon the number of entries received there will be a minimum of 3 maybe 4 rounds flown.
Gates to the site will be open at 8.00am and then locked at 9.00am
Pilots briefing 9.15 -  First flight (electric) 9.30
A reserve list will be in operation if /when16 entries are received.

Airfield directions;
The entrance to the airfield is found on the East side of the town, off the A52 Derby road.
From the East (Derby), as you approach Ashbourne on the A52 you come to a crossroads for Osmaston (left) and Bradley (right), Lady Hole Lane. Turn onto Lady Hole lane and approximately 400yds past the first entrance on the left is the entrance to the airfield.
From the West (Leek), continue through Ashbourne following the signs for A52 Derby, do not follow AIRFIELD INDUSTRIAL ESTATE signs, again you will  approach a crossroads, turn left onto Lady Hole Lane.
PLEASE NOTE when entering the airfield please stay on the main runway and proceed to the factory directly in front of you. Turn right and following the dirt track to the green hut.

CD Adrian Harrison
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Competition News / Re: Ashbourne event 22/09
« Last Post by Adrian Harrison on Today at 08:53:49 am »

Yes it is and yes it is just complete an entry form in the normal way.
Who am I responding to please?
Adrian.
7
For Sale and Wanted / Contra prop set
« Last Post by Ian Mould (Mouldy) on Today at 07:32:44 am »
Mejzlik contra prop set. 22 x 18 EL F and 22 x 20 PEL R.


£100 +p+p


Can bring to the Nationals
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General Pattern Discussion / Re: Turbulator tape
« Last Post by Mike Wood on Today at 07:13:26 am »
Malcolm

Completely agree with you about "locked in" models and how "identical" models can be different.

We often hear about flying "on rails" but I think the differences are more subtle. Relatively speaking
they all fly on rails compared to other types of aircraft.

Perhaps a little like identical shopping trolleys, some are more wilful than others when trying to go in
a straight line.

Peter, nice post!

Mike
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General Pattern Discussion / Re: Turbulator tape
« Last Post by Malcolm Harris on Today at 06:48:04 am »
Hi Peter,
I think you have to consider exactly why we are interested in adding turbulator tapes.


The free flight guys are interested in making their models stay up longer presumably by improving the lift/drag ratio.


I was interested in something else entirely which was to try and make an unpredictable model “lock”. I don’t know how to describe that phenomenon but anybody who has flown dozens of models will know the ones that do and those that don’t. The nearest I can come to a description is that the model feels like it’s flying in sticky air. So the purpose of adding turbulation was exactly to cause more drag and hopefully create the “sticky” feeling.


I apologise for being so unscientific in the above description but until someone can tell me how to define this elusive quality I don’t know how to be any more precise.


Incidentally, old hands will confirm that identical models with identical setups (cg, throws, incidences, thrust lines) can feel totally different in the air. This phenomenon has always been the most puzzling to me in nearly 40 years of aerobatic flying.


Malcolm
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General Pattern Discussion / Re: Turbulator tape
« Last Post by Peter Jenkins on Today at 12:36:21 am »
Hi Keith, the purpose of the turbulator is to trigger the transition from laminar to turbulent flow.  Since laminar flow tends to detach in an adverse pressure gradient i.e. the flow speed is reducing, it is usual to site such devices close to the leading edge than max thickness.  At max thickness, if the Reynolds number is around 700,000, then you are more likely to achieve flow separation than encourage the airflow to stay attached.  If you look at where the FF boys put their turbulators (10-15 % back from the LE, that should have a beneficial effect.  But, it all depends. Stick some string down with cellotape and experiment with different thickness of string starting with the thinnest you can find.  If you can arrange for a test in a smoke tunnel you will see what effect varying string thickness has on the boundary layer.  Unless you have access to some powerful computational fluid dynamics software, it's "how thick should the piece of string be and where's the optimum place for it?"  I'm pretty certain that at the Reynolds numbers we operate at, mid thickness is unlikely to be the optimum position.
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