WMAC Group build - Impressivo

MikeSeale wrote:
I see in the instructions that you can go for the servo exits on top of the wing or underneath and see you've gone 'down under'. I think I'll do the same but wondered if there is a reason for this other than personal preference.

I assume going on top of the wing would be to protect the linkage and horn when landing, which I would think would be sensible when landing on grass.

flyingpete wrote: Blimey Jon that is blast from the past!! Last time I saw one of those was at Beaulieu in the mid 70's

Definately a piece of modelling history Pete, been reading up a bit on it, Hanno used it to win his first Worlds in 1977! So it would probably have been around the late 70's over here. When I started out in F3a in '86 I think, my old mate Phil Mitchell was flying one, covered in nylon and painted as I remember, it weighed a ton but still flew really well. The kit is really nice and it's going to turn out much lighter than the originals, should be fun

Jon said

I assume going on top of the wing would be to protect the linkage and horn when landing, which I would think would be sensible when landing on grass.

Just a thought provoked by the comments about getting the servos into the rather thin wing. How about putting them in the fuz and driving the elevons with torque rods just like we did in the old days of a single aileron servo?

I've not yet got my kit but looking at the pic of the model PhilC let us think he'd built it certainly looks a possibility. I suppose flutter could be a problem but as the elevons are not in the draft of a prop it should be ok if the torque rods are strong enough to resist twisting.

David

Hi Dave

I don't think torque rods would be a good idea in this type of model - Its a recipe for elevon flutter !

Haven't collected my kit yet but i can't imagine that the original 11mm x 23mm servo footprint can't be opened up to 12mm x 24mm of which there are many cost effective digital MG servos with 2g/cm torque available.

Got my kit and shortly after admiring the superbly machined parts my glue started to dribble from its nozzle resulting in a completed fuselage crutch assembly. However, i am holding off fixing the rear former R9 for the motor because mine has not arrived yet.

Q. Has somebody in the build group got both kit and motor and if so please advise if the Motor profile fits this bulkhead or would it be better to make one specific to our elected motor.

Motor bulkhead fits the motor perfectly...just glue it together and the motor will slot straight in when it arrives, Kevin.

Fitting 12mm servos will require a little modification. By the look of it, ply parts F19 and F20 create a 'frame' for a 9mm servo and then balsa parts F21, F22 and F23 closes the structure before covering. F20 is 1.5mm in from the profile of the ribs and it wouldn't take much to drop this part down to the rib profile which would give an additional 1.5mm for the servo thickness. The inside of balsa part F22 could then be sanded 1.5mm at one end to clear the servo. I'm not going to order any servos yet, but here are some options to ponder...

Savox 0255 = £16.45 Metal gear, 1BB, digital, 12mm

New power XL-17MB = £10.99 Metal gear, 1BB, digital, 11.6mm

Ripmax SD150 = £15.95 Plastic gear, no BB, analogue, 9.1mm

I've used all of the above in one model or another. The SD150's are currently driving the ailerons in my F5B model...the one that does 150mph+. Food for thought?

Mike

Anyone worked out the angle at which F9 (motor mount) is set in ralation to the datum line, and where is that? Visually, it looks like it is NOT at right angles to a line through the holes for the carbon rods, and shows an angle of upthrust.

Never built a pusher before. :S

Since the parts all interlock, you have no choice but to build it as designed and you will end up with the correct degree of up/down thrust. Any attempt to alter the way the parts fit together would be a big mistake, IMHO, because I'd assume that the designer has got it right.

BTW, Phil, you asked about a folding prop a while back...not worth considering on this model. A folding prop will be more expensive, less efficient and more likely to be out of balance. The only advantage a folding prop brings is that it won't break on landing, but I've not broken the fixed APC props yet, so do not consider it a problem that needs solving.

I can confirm that the parts are so accurate - everything fits like a glove - Just make sure that when you join the two previously laminated fuselage sides together, you fit the false floor F7 tight against bulkhead R4 - This will set the fuselage accurate.

I fabricated my fuselage sides using a contoured building board which made pulling the pre laminated fuselage sides together at the nose bulkhead a breeze. If other builders wish to make use of this its available. Its all jigged to locate the sides using the carbon dowels and forces you to make left & right handed sides - see photo.

Anyone taking progress photos to use later for an article?