Search found 37 matches

by Dave Cooper
January 16th, 2014, 4:04 pm
Forum: Technical Help required
Topic: High Temp Epoxy
Replies: 9
Views: 2224

Re: High Temp Epoxy

Hello Kate. I am currently building a carbon-fibre based racing sportscar (own design). We use machined dural 'bobbins' to accept the various threads in the chassis. These are bonded into the carbon panels using a high-specification adhesive. Where high temp's are involved, it's best to source the c...
by Dave Cooper
November 10th, 2013, 3:48 pm
Forum: Technical Help required
Topic: 1/4 Scale Wyvern Prop Blades
Replies: 4
Views: 1106

Re: 1/4 Scale Wyvern Prop Blades

Thanks Tinus. They look like they have the right sort of products / engineering expertise I'm looking for.

I've sent them an email enquiry to see if they can help...
Dave
by Dave Cooper
November 1st, 2013, 3:46 pm
Forum: Technical Help required
Topic: 1/4 Scale Wyvern Prop Blades
Replies: 4
Views: 1106

Re: 1/4 Scale Wyvern Prop Blades

Thanks Paul, I have spoken to Solo in the past and they seemed reluctant to move away from their standard offerings. They do make nice 'ground-adjustable' hubs though which is tempting ! I think I may well have to lay-up some blades to a standard design unless something else turns up. I'm a bit worr...
by Dave Cooper
November 1st, 2013, 10:05 am
Forum: Technical Help required
Topic: Melting lead for ballast
Replies: 8
Views: 1723

Re: Melting lead for ballast

Steve - glad to hear the safety side is up to scratch ! I wonder if there's any scope to move engine /cowl further forward a few mil's ? I had to do this recently on an electric conversion and found that around 4-5mm did the trick without spoiling the scale effect and better than carrying all that d...
by Dave Cooper
October 31st, 2013, 10:42 pm
Forum: Technical Help required
Topic: Melting lead for ballast
Replies: 8
Views: 1723

Re: Melting lead for ballast

Steve - just as a safety feature, make sure that there is no water / moisture etc. trapped in the bottom of the tin before putting the solid lead in. I use your method too, plus, I use some heat-protective gloves (same as for putting logs in the wood-burner). Lead splatter /burns can be nasty. Also,...
by Dave Cooper
October 30th, 2013, 9:22 pm
Forum: Technical Help required
Topic: 1/4 Scale Wyvern Prop Blades
Replies: 4
Views: 1106

1/4 Scale Wyvern Prop Blades

Does anyone know where I can find some large diameter prop blades ? The overall (scale) diameter is some 39". I need one tractor and one pusher blade set for the contra-rotating set-up (3 blades to each hub). Ideally, I would like ready-balanced 'carbon' blades but a good quality wood set would...
by Dave Cooper
July 8th, 2013, 3:32 pm
Forum: Technical Help required
Topic: Amps or Air for 1/4 scale Wyvern ?
Replies: 7
Views: 1386

Re: Amps or Air for 1/4 scale Wyvern ?

Thanks for the input on full-size Chris. Rob - I've had a look at my Tx and there's a rotary knob on it with a full 270 deg's of travel. I like the simplicity approach and I reckon that this knob could be accidentally nudged in flight without any ill-effects ie with wing-fold / unfold at the extreme...
by Dave Cooper
July 7th, 2013, 9:55 pm
Forum: Technical Help required
Topic: Amps or Air for 1/4 scale Wyvern ?
Replies: 7
Views: 1386

Re: Amps or Air for 1/4 scale Wyvern ?

Hi Rob - thanks for the reply, I guess the main problem with a pure transmitter-based interlock for the u/c 'down' switch position would be that the wings could still be folded during take-off and landing ? I had in mind some sort of oleo leg extension sensor to give the following control logic :- M...
by Dave Cooper
July 7th, 2013, 8:49 pm
Forum: Technical Help required
Topic: Amps or Air for 1/4 scale Wyvern ?
Replies: 7
Views: 1386

Amps or Air for 1/4 scale Wyvern ?

I wonder if more experienced members could advise on whether to use electric or pneumatic actuation / locking for my 1/4 scale Westland Wyvern. The various mechanisms are as follows :- Retractable Main gear Retractable and steerable tailwheel Double wing-fold (mid panel and tips) Power canopy open /...
by Dave Cooper
October 4th, 2012, 11:12 am
Forum: Your New Projects
Topic: 1:4 Scale Westland Wyvern
Replies: 10
Views: 4733

Re: 1:4 Scale Westland Wyvern

A quick update on progress : The Mk 1 gearbox contained a fatal flaw in the tooth design. This has now been identified, corrected and a quote received for a new design. The fault was actually a geometrical one (by me, not the supplier) and it involved the teeth spacing of the internal ring that reve...
by Dave Cooper
June 9th, 2012, 9:29 am
Forum: Your New Projects
Topic: 1:4 Scale Westland Wyvern
Replies: 10
Views: 4733

Re: 1:4 Scale Westland Wyvern

Thanks for the engineering contact David. As soon as I've finalised the design I'll make some detail working drawings and get in touch...
Dave C
by Dave Cooper
June 7th, 2012, 3:20 pm
Forum: Your New Projects
Topic: 1:4 Scale Westland Wyvern
Replies: 10
Views: 4733

Re: 1:4 Scale Westland Wyvern

This is a cut-away of the full-size pitch-change system - needless to say the 1/4 scale version will be somewhat simplified !
by Dave Cooper
June 2nd, 2012, 9:14 am
Forum: Jets
Topic: FlyEagle 1:4.5 Hawk
Replies: 6
Views: 3384

Re: FlyEagle 1:4.5 Hawk

Hi Keith I'm new to jets - did you find the cause of the flame-out ? I need to learn about these things ! ps also found the same handling quirk on my PC Flight Sim' - just added more "thrust-to-weight" so the lower throttle settings leave more rpm on. Don't know if this will work in 'real ...
by Dave Cooper
May 29th, 2012, 11:12 pm
Forum: Your New Projects
Topic: 1:4 Scale Westland Wyvern
Replies: 10
Views: 4733

Re: 1:4 Scale Westland Wyvern

The Mk 1 contra-gearbox is nearing the end of it's test life. The rear prop has been repaired twice and I have now consulted with a specialist gear manufacturer for some quotes and extra assistance with tooth profiles, gear ratios etc. Lessons learnt so far :- 1. Wooden mock-ups are great for gettin...
by Dave Cooper
May 12th, 2012, 10:56 am
Forum: Technical Help required
Topic: Washout with double wing-fold
Replies: 15
Views: 4879

Re: Washout with double wing-fold

Robin - thanks for demystifying this. I knew that the last 2 digits related to thickness but was not aware of the meaning of the others.

I will certainly look at, and study, the other programs and files that you mention...
Dave
by Dave Cooper
May 11th, 2012, 3:03 pm
Forum: Technical Help required
Topic: Washout with double wing-fold
Replies: 15
Views: 4879

Re: Washout with double wing-fold

Thanks Chris, Robin - I see that I shall have to make myself more aware of the contents of the LMA website ! Quick question : In the Public Domain Aerofoil listings (Abbott & Doenoff), it shows two sets of ordinates for the 65-212 section (which are quite different) and none for the 65-214...do ...
by Dave Cooper
May 10th, 2012, 10:21 pm
Forum: Technical Help required
Topic: Washout with double wing-fold
Replies: 15
Views: 4879

Re: Washout with double wing-fold

Hi Chris - the two NACA sections that you mention - were they for another Wyvern model or, the full-size perhaps ? (The gearbox info' is very useful. I also found this a while ago...it incorporates the reduction gear as well as the main prop drives and reversing gears. I also have a cutaway of the R...
by Dave Cooper
May 10th, 2012, 5:32 pm
Forum: Your New Projects
Topic: 1:4 Scale Westland Wyvern
Replies: 10
Views: 4733

Re: 1:4 Scale Westland Wyvern

Hello David Making a good recovery thanks, but, the workshop is still a bit too cold for serious build sessions. Still shaking the bugs out of the contra-box design but am now close to ordering the metal gearset from a specialist supplier. So far, I've only looked at the Wren 44 and Jetcat TP's. One...
by Dave Cooper
May 9th, 2012, 10:28 pm
Forum: Technical Help required
Topic: Washout with double wing-fold
Replies: 15
Views: 4879

Re: Washout with double wing-fold

Thanks for the tip on aero' washout Phil. I had considered this but, don't yet know enough about the selection criteria for the two different sections - root and tip. I'll have to start reading "Abbott & Doenoff" again ! On my Phoenix RC flight sim' there's a Bearcat (nearest I can fin...
by Dave Cooper
May 5th, 2012, 10:58 pm
Forum: Technical Help required
Topic: Washout with double wing-fold
Replies: 15
Views: 4879

Re: Washout with double wing-fold

Thanks for the replies so far - looking through my full-size tech file, the root incidence is set at +1degree. By visual estimation of a 3-view, the tip TE looks to be about 1 to 1.5 degrees above fuselage datum. So, I estimate about 2-2.5 degrees of overall washout. The test pilot's reports (Harald...

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