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Member postings for Robert Welford

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

Thread: Fuel Agitation
08/11/2019 10:16:37

Most felt clunks are used with petrol engines and turbines. The YS variant was smaller - unfortunately YS bits are now difficult to source within the UK.

Alan, you'll have to see what will fit through the opening of your fuel tank. Sintered clunks will also eliminate the effects of bubbles. Search online and you should find what you are looking for.

07/11/2019 22:35:06

I've experienced issues with YS engines due to bubbles in the fuel supply. The solution is to use a felt covered clunk.

Hope this helps.

Thread: Crashed my Spitfire now i will repair it
27/09/2019 12:05:13

Nice repair Stephen. I agree with Eng. Dr. if you use new parts and splice in new wood where needed any weight increase will be very modest.

Edited By Robert Welford on 27/09/2019 12:06:46

Edited By Robert Welford on 27/09/2019 12:07:14

Thread: Ripmax Phase 5e
13/09/2019 22:57:16
Posted by Peter G Simpson on 09/09/2019 11:05:20:

The final observation is the tailplane. The instructions seem to imply that you simply slide the tailplane halves onto their piano wire mounting and use the friction of the piano wire to prevent them from parting company from the fuselage. I wasn't happy with this so put a spot of glue on the wire joiner to hold the tailplane halves in place.

The usual way of achieving this with an all moving tailplane is to put a slight bend in the end of the secondary tailplane joiner not the pivot wire.

Thread: Aileron Thickness
13/09/2019 22:53:03
Posted by Capt Kremen on 13/09/2019 17:35:07:

Interesting replies.

I have a American flight school book, ("Airplane & Radio Setup" by David A.Scott), which states do not 'bevel' ailerons but 'round' them. Also ... make the ailerons thicker. Author Mr Scott, who runs a long established R/C flight school and is also a qualified full-size display pilot, describes the advantages/theory of these actions. i.e, re-energize (US spelling LOL!) the airflow over the ailerons to maximise control authority and generate a linear control response. Also ... his 'Rule of Thumb' quote" Raise the aileron, elevator and rudder approx 1/16" each side - 3/32 to 1/8" thicker overall"

You can check out his Flight School books and download illustrated sample pages.

My 'flying field' experience, seal the gaps first and foremost, all the other ideas???? maybe/maybe not, my skills can't deduce any discernible improvement (or degradation!).

I suspect the reason for making the thickness of the control surfaces thicker than the adjacent part of wing or tail is to trip the airflow and control the point at which the airflow becomes turbulent. This will give predictable transition to turbulent flow and give better control response and possibly reduce drag.

High performance full-size gliders trigger the the transition point just in from of the flaps and ailerons either by the use of zig-zag turbulator tape, or by using blown air holes. In this case the objective is to reduce drag.

Thread: Prop failure
14/08/2019 12:09:41
Posted by Jon - Laser Engines on 14/08/2019 11:58:07:

I have made numerous sandpaper washers and they work really well. I used 240 and 400 grit so far, both worked fine.

Thanks Jon. I will go this route.

14/08/2019 11:48:59
Posted by Ronaldo on 14/08/2019 10:54:33:

On the subject mentioned earlier of the ali spinner drifting on the back plate and the 'cut out' edge fouling and digging into the prop hub, I've had this happen with and without using a starter. Now I 'peg' the back plate by drilling and tapping into the edge where the spinner edge sits in the groove, and fitting a m3 x 5mm grub screw, securing with a drop of thin cyano. I then fit and line up the spinner and prop against the back plate to give good clearance so as not to touch the prop hub, then file a notch in the spinner back edge/rim to fit over the grub screw. Never moves now, even when using heavy duty starter.

I've just starting flying a Toni Clark (TC) CAP21 with a Zenoah 62. I'm using a carbon propeller together with a TC spinner. The spinner is epoxy grp with a nylon back plate. I notice after running the propeller rotates slightly relative to the spinner. The engine is hand started. I tighten up the single prop bolt as tight as I can, but the problem is that the surfaces of the propeller and spinner backplate are smooth. The Zenoah's prop driver is serrated.

I thought of making a double sided washer from 120 grit glass paper placed between propeller and spinner backplate. Anyone any other suggestions?

05/08/2019 12:53:53

Jon, what engine is the propeller/spinner off? 20x10 wood - I assume not a Laser 4 stroke.

Thread: Wot 4 Squared
23/07/2019 09:16:45
Posted by Concorde Speedbird on 22/07/2019 22:08:02:

Bit of a delay, I've been fairly busy doing quite a bit of this


Jacob, where are you paragliding? Is it Snowdonia?

Thread: Multiplex Dual Receivers
17/07/2019 20:51:21

Peter, I've sent you a message. Robert

Thread: C of G Question
02/07/2019 20:14:05

Assuming normal tailplane area and tail moment 30% of mean wing chord is a good starting point for CofG.

See recent "CofG" thread for in-flight testing for appropriate CofG position.

Thread: CofG
14/06/2019 14:10:44

Yes I agree it sounds like the CofG is nose heavy - too far forward

To assess the CofG position for powered aircraft: trim for level flight; pull into 45 degree upline; roll to inverted and observe the trajectory. Aircraft should gently descend whilst inverted.

If the (inverted) aircraft pulls down => CofG too far forward

If the (inverted) aircraft pulls up => CofG too far back

If the aircraft trajectory stays constant at 45 degree upline => CofG maybe ok for 3D, but still too far back for general aerobatic flying.

For gliders dive (in trim state) in a 45 degree downline and see what happens.

Thread: David Vaughan P-51B
08/05/2019 11:38:42

Richard, do you now own David's original P-51B model?

I remember reading the original build article in RCM & E. The model was and still is a masterpiece.

Thread: Curare Plan
27/04/2019 16:48:28

Thank you CP for the pointer to the Curare CAD plan.

I currently fly a Schweighofer version of the Curare, but I'm also interested in building one based on the MK plan.

Thread: New Drone/Aerodrome Regulations - Is your club at risk?
17/04/2019 14:14:43
Posted by Piers Bowlan on 17/04/2019 13:29:36

Robert, an airband radio seems like a very practical and sensible safety aid to alert flyers to the presence of full size aircraft joining the Old Wardon circuit. Maybe a case of 'Not invented here syndrome', as far as your committee is concerned. An active aerodrome - why wouldn't you want to know who is in the circuit apart from model aircraft?!

To operate an airband transceiver you need an RT licence, but not an airband receiver. They cost from less than £100. Yes - agreed it's a no brainer.

17/04/2019 11:31:15

David, if you were asked to release the data to a 3rd party would you and possibly incriminate yourself?

17/04/2019 11:26:49

Piers - yes the 400 ft height club rule is unenforceable, but it won't stop the OW "Safety Police" from claiming you are flying too high. I been criticised in the past for flying too far away!

Like Martin I have instrumented a few models with altimeter telemetry (via my Multiplex radio) to see how low 400 ft is particularly when flying aerobatics.

The real problem is that we operate on an active airfield. The procedure is that models are required to land as soon as full-size aircraft commit to an overhead join. On occasions aircraft have come in directly on finals and haven't been spotted, so the most dangerous height band is 0 to 200 ft.

I have suggested that we operate airband receivers on the Old Warden frequency to enhance our situational awareness of traffic intending to land. The committee didn't like that as an idea.

Edited By Robert Welford on 17/04/2019 11:32:31

16/04/2019 23:21:49

I agree Martin. I'm involved in other clubs; another model club and a full-size gliding club and both are run very democratically with important issues communicated and discussed with the membership.

I would have thought a 400 ft height rule was a sufficiently important issue that needed to be discussed with the membership.

I'm am member because Old Warden airfield is a great place to fly. Going forward how we resolve this and other issues requires further consideration.

Edited By Robert Welford on 16/04/2019 23:22:44

16/04/2019 20:41:08

Sadly we are "not out of the woods" yet.sad

Despite the latest amended CAA Exemption allowing normal height limits (none for < 7kg, 400 ft >7kg) for Old Warden Model Aircraft Club, the club committee have decided to retain the 400 ft height limit that was introduced with CAP 1763 on 13 March 19.

The committee have refused to provide any justification for their decision and before you ask it isn't the Shuttleworth Trust who are insisting on a height limit.

The only upside is that if anyone were to fly higher than 400 ft for < 7kg (inadvertently) they are no longer in breach of the CAP 1763, but only of the club rule. In addition, model flying events are now free to have no height limit. smiley


Edited By Robert Welford on 16/04/2019 21:05:36

10/04/2019 18:18:47
Posted by Andy Symons - BMFA on 10/04/2019 17:37:42:


Thank you Andy and your colleagues for resolving this issue with the CAA. This means that model events and club flying at Old Warden may no longer be affected by the FRZ 400 ft height limit


Edited By Robert Welford on 10/04/2019 18:19:21

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