SDF
-
Posts
61 -
Joined
-
Last visited
Never
Content Type
Profiles
Forums
Blogs
Gallery
Calendar
Downloads
Everything posted by SDF
-
I'd steer clear of Epson. They are fantastic while they are working but I used more ink cleaning the print heads than printing and when they finally blocked for good a replacement was more than the cost of a new HP printer.
-
Thanks I'd forgotten about Enya but they do look like modified glows which doesn't often work well. I had a repsonse to my e-mail to Tom Ridley today and he is still producing John Oliver's range of diesels. They aren't cheap and there is a waiting list but I'm very tempted, I just need to descide what I want (kid in a sweety shop).
-
Most of my flying over the last 35 years has been with diesels, control-line and free flight. It is rather sad that there are so few being made now as they typically outperform glows below 2.5cc. The only three major manufacturers I am currently aware of are: PAW still with a full range; CS offering some reproductions of classic british diesel designs; MVVS with only a 10cc monster. There are no doubt a few cottage industry products but that appears to be about it. I think it may be time to stock up while I still can.
-
Control line Super Tamerlane. Not held a handle for about 10 years - thoroughly enjoyed it.
-
The original design only has the one spar so it sounds like I will need to add a second but I think only as far as the dihedral break. I was planning to cover the wings with lightweight glass cloth on the outside but I could do the inside of the wheel bays too. Does the TF kit use a ply plate or hardwood bearers to mount the retracts?
-
Inertia is really what the bottom two pictures were getting at. The centre of mass tends to continue in a straight line as you say but it is someway above the wheels so the outer wheel in the turn gets loaded more and "steers" either into or away from the turn. Our strip is sufficiently bumpy that I probably wont be able to tell the difference between toe-in and toe-out anyway but perhaps I should leave it adjustable to begin with. The next problem is how to make the wing centre section structure strong enough to mount the retracts without adding too much weight.
-
I thought I wanted toe-out but now you have me wondering. There seem to be conflicting views on this, both with full-size and models, with about a 50-50 split toe-in vs toe-out. The toe-out camp argue that a turn on take-off / landing transfers load from the inner to outer wheel and the toe-out tends to self-correct the turn making ground loops less likely. The toe-in camp's argument is if the aircraft is yawed with respect to the direction of travel the leading wheel is at a greater angle than the trailing wheel so producing more drag which tends to reduce the yaw. I think the toe-in argument may be flawed as it seems to assume there is no turn associated with the yaw.
-
-
This may take some time - my builds usually do - but I'm going to build a Hawker Sea Fury from the Pete Nicholson plan. I want to fit retracts and flaps so some mods will be required. First problem is retracts: I plan to use the E-Flite electric ones. The wing as drawn has a 9.5% thick flat bottomed section which was probably ideal on the Speed 600 powered original but is too thin to fit the retracts. The full size has a Hawker high-speed aerofoil 14% thick in the centre section but I’ve chosen to go with a Selig S8036 designed for the Top Flite P47 thinned from 16% to 14%. Now we come to the angle of the dangle - The retracts on the full size rake forwards at an angle of approximately 16 degrees when extended and rake back at an angle of 20 degrees when retracted. How do you achieve that? Help was found here but not wanting to bend the legs I have chosen to use 18 degrees for both. Being a sceptical so and so I wanted to convince myself that this would give the right angles with the leg close to vertical extended with a couple of degrees of tow out and lying flat in the wing when retracted. The pictures were generated using POV-Ray to model the retract in the S8036 wing to ensure everything was pointing in the right direction. The video shows the retraction animated. Electric Retract Model from SDF on Vimeo.
-
-
-
-
-
60/40 Sn/Pb rosin multicore for electrics and with Fluxite for metalwork.
-
I used to make all my control line tanks never done one with a clunk though. The thinners tin should be fine for material but clean off the paint along the edges to be soldered. Use brass tubes as copper goes green and yucky (technical term) with glow fuel. I would avoid plumbers solder as this has been lead free for some time and it simply isn't as good as the leaded stuff. Use a separate flux, personally I prefer Fluxite as its less corrosive than Bakers Fluid but either would be OK. Tin the edges to be joined with flux / solder before assembly. Clean then add fresh flux and solder it together. Ensure there is a good fillet of solder anywhere you cannot have a proper flange. Thoroughly clean off any flux residue inside and out after soldering with solvent as this can hide leaks. Good luck.
-
Peter Millers Harlequin Build Blog (electric conversion)
SDF replied to Geoff Bradley's topic in Build Blogs and Kit Reviews
I shall be interested to see how this goes. -
If your using a 12v battery as a power source a simple temperature control can be made using the spring from an old roller blind. Connect one side of the battery to the salvaged spring and the other side to the cutting bow. Then connect the remaining end of the bow partway along the spring using a crocodile clip. The closer to the battery end of the spring you move the croc clip the hotter the wire in the bow will get.
-
Help with Power System for Harlequin
SDF replied to Geoff Bradley's topic in Peter Miller plan builders
For my own ammusement I thought I would try to calculate what a suitable setup might be. I believe Peter had an OS40FS in his original, 0.64 bhp at 12000 rpm according to OS. There are 746 Watts (ish) per horse power so the OS gives 0.64 x 746 = 477 Watts of output power. Assuming our electric motor is 75% efficient we need 477 / 0.75 = 636 Watts of input power. With 4S LiPo nominal 14.8 volts thats 636 / 14.8 = 43 amps. Output power = torque (Nm) x angular velocity (rad/sec) 477 = T x 12000 x 2 x pi / 60 so the torque is T = (477 x 60) / (12000 x 2 x pi) = 0.38 Nm Motor torque constant, Kt, is torque divided by current. Kt = 0.38 / 43 = 0.0088 Nm/A Kt is numerically equivalent to Kv measured in volts/radian/second. The Kv quoted for brushless motors is however expressed in rpm/volt Kv = 60 / (2 x pi x 0.0088) = 1085 rpm/volt So based upon that with a 4S LiPo you would need a 1085Kv motor large enough to handle 636 Watts and 43 Amps. For example one of these might fit the bill. I've not tried to apply this method to electric flight before so have no practical evidence to back it up but the result does seem to be consistent with the general consensus above. -
RLG, having a bit of a Spinal Tap moment there? I hope you mean 8' and 2"
-
Help identity rubber powered Cub manufacturer from 1990's please!
SDF replied to Cris Oxley's topic in Beginners
Alan, Why arn't they made anymore ... x-box, playstation, wii ... need I go on? Mine was one of the last pre-computer game generations (if you don't count Binatone TV Tennis) and all the better for it in my opinion. I have a feeling I should have an unbuilt Hyper Cub somewhere (or it might be that kit was too expensive at the time) but can't quite remember. I certainly had the Rare Bird glider from the same range. -
Help identity rubber powered Cub manufacturer from 1990's please!
SDF replied to Cris Oxley's topic in Beginners
Hello Cris, I think the advert you refer to is for DPR models (now Flying Toys) run by David and Jannine Rawlings and the model would be their Hyper Cub. Edited By SDF on 06/06/2012 22:40:48 -
re nitro damage - usually corrosion caused I believe by nitric acid created during the combution process.
-
I've been away from the hobby for a few years and one of the most noticable things coming back is the lack of kits. My LMS carry none apart from a few West Wings rubber models and there seem to be very few kits advertised. Fortunately I have a few kits stashed away but it looks like from now on if you want a traditional build the choice is going to be magazine plans or DIY designs.
-
1.75cc FROG 1948
-
As Steve W-O says you really shouldn't abrade the tip. The correct method is to use tip tinner/cleaner to remove the oxide layer and re-tin the tip. It seems to me that modern tips need this treatment more regularly.
