David Ramsden

I've heard back from Stan at Phoenix MP, definitely not one of his designs so it remains a mystery. David

Hi Wookman. Yes I agree it probably had a symmetrical or semi airfoil. It's very much like Stan's Virage design but the tail outline and airfoil are different. I have emailed Stan to see if he can throw any light on it.

Hello! I recently bought this fuselage (wings missing) from a DSSC club sale thinking it might be a Chris Foss design but it seems it's not one of his 'phase' designs. It has an all-flying tailplane, a very large rudder, a pronounced tail skid shape, a pine nose skid, and seems to be wired for ailerons and flaps. It's 118cm long. Sadly, the previous owner/builder is deceased. Any ideas? many thanks! David

Hi again. So, I finished the wing center-section, bottom-hinged the flaps with the covering film, and added gap cover tape I bought from Hyperflight. I had a couple of problems with the tape and Neil at Hyperflight very kindly gave me a refund. After a few attempts and a lot of fiddling I decided best thing to do was cut the tape down to 15mm leaving 10mm of adhesive and only 5mm of clear tape to cover the gap. I'm still not entirely happy with it but it's easy to peel off and re-do. Here's the result so far; flaps up; about 7 degrees down; about 15 degrees down, and all the way down which is about 80 degrees.

Great advice Simon. Point taken. Thanks. I noticed that Hyperflight also do one. https://www.hyperflight.co.uk/products.asp?code=F-RMXGT1&name=gap-seal-tape-20mm Might be better than Ripmax. I'm a bit incapacitated at the moment but when I've finished the flaps I'll post a pic. Have a great year. David

Thanks Simon, With my long thin solid balsa flaps I agree "trouble and effort to set it up is not really worth any minute performance gain". All posts considered, I think I'm going to go for a dead simple bottom hinge (as per the sketch at the top of the thread) and use a cover tape like this https://www.sussex-model-centre.co.uk/ripmax-gap-tape-20mm-5m (on the top) cut down so that it only just covers the <3mm gap that will open up at 10 degrees down-flap. If the tape is a bit 'soft/floppy' then cutting down the gap-cover to only a few mm should reduce the chance of it being sucked up into the reduced pressure over-wing air flow. I might just round-off the top edge of the flap very slightly so that if I go from full-down to full-up there's no danger of the top of the flap catching on the rear edge of the tape. Thanks everyone for the advise. Much appreciated. David

Hi Nick, Yes. Me too. That's the method I've used on all my ailerons and flaps but with film rather than tape. The ailerons on this model (photo at top of thread) are top hinged like that too. The reason I started this thread is because I don't need the flaps to go up (so top-hinging is not needed) and I want them to come down about 80 degrees (which top hinging wouldn't allow). That's why I'm looking at bottom hinging for the first time.

Thanks Simon, that certainly looks like the ultimate solution but how would I actually build/install "extended individual hinge mounts" and how many would I need on a flap that's about 400mm long? Please do you have any photos of hinge mounts like that? Thanks.

Thanks Don, Pat, and Simon, Pat, with your ABC flap/spolier setup, I'm surprised that in position B the model gained more (in lift) than it lost (in drag) but that actually makes me think that with the simple bottom-hinge setup I am thinking of (as per diagram at top of thread) the same would be true (at 10 degrees down I'd gain more than I lost) and so a top-gap-cover is unnecessary. Mind you, I rather like the gap cover on your ailerons. I saw an advert recently for plastic draught excluder tape on a roll which was very thin and self adhesive down one side. Maybe that would work. Simon, I'm not entirely sure what "off set pivot points and matching profiles between the wing and flap" would look like. Is it weaker and more complicated than a full-length simple film hinge? Please excuse my ignorance. David

Thanks Martin, that sounds like a very good idea. At 10 degrees down I reckon the top gap will only be 2mm, 3 at the most. What would you do? Glue a strip of very thin ply to the top of the trailing edge recessed into the top of the flap?

Hi Pat. Thanks for that. Do you think that a downward deflection of 5 or 10 degrees at normal airspeed would add any lift (with bottom hinging) or would the gap in the top surface negate the benefit?

Hi Alan. I don't know. What would that look like?

I'll soon be trimming the TE, final sanding, and cutting out the flaps on the new center-setion of my DR 420. Because I don't need the flaps to go up, it occurred to me that I could bottom-hinge them rather than top-hinge. My thinking is: Top-hinged flaps in normal flight would have the advantage that I could drop them a few degrees to increase camber without interrupting the airflow over the upper surface, or drop them 45 degrees to act a bit like airbrakes. But, the disadvantage would be that the under surface airflow would be disrupted nearly all the time. Bottom-hinged would have the advantage that both the top and bottom airflows would be uninterrupted in normal fight and dropping them 45 degrees would badly disrupt the upper surface airflow but this probably wouldn't matter and might even make them more effective as 'brakes'. But, the disadvantage would be that dropping the flaps a few degrees to increase the camber would interrupt the top-surface airflow which might more than override any extra lift created. So maybe, If I DO want variable camber top-hinged will be better and, if I DON'T want variable camber, bottom hinged will better because it will give me maximum wing efficiency and better braking effect. Am I right? Thanks! And Happy New Year, David

Hi Nigel, Peter, and Simon. Thanks for the advice on spar tapering and shear webbing. When I said "two parallel carbon tube spars" I wasn't thinking of 'one above the other', I was thinking of 'one behind the other' with the forward one being the main spar glued to the back of the 'D box' sheeting and the rear one being half the diameter running through the unsheeted part of the wing. These would line up with (and accept) the rods protruding from the outer wing sections (that plug in to the center section). I'm confident this will be much stronger than the previous single spruce spar but I obviously can't taper them and there will be a weight penalty.

Hi Martin. I looked at the Bubble Dancer wing plan. Looks like a balsa spar with carbon caps. Interesting stuff. Maybe one day!