Rob Ashley
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Dave, I found this really interesting - thank you for publishing this. Have you thought about submitting this to the monthly mags for publication - I think this would be a cracking article? Rob
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Posted by Anthony Scott 2 on 17/04/2018 17:24:49: Ascending spin? Most definitely Anthony - a spin is an autorotation so can be ascending or descending. Getting an aircraft to spin upwards is quite satisfying. Speed is most often related and attributed to stalling as, historically, in full size flight there was no way of reading AoA, but airspeed is easily obtainable. So correlations were found that at certain speeds in certain flight regimes speed could be used to determine the stall point. Problem is the stall occurs at an AOA not a speed. The faster you go the more lift the wing generates but the critical AoA doesn't really change until we get toward high speed problems such as compressibility (even then not much), which not generally a problem with models - but it means that irrespective of speed you can exceed the critical AoA and therefore stall at any speed. As for entry to a loop, you can pull hard on the elevator and get the aircraft to depart quite easily as the critical AoA has been exceeded (even with rudder and ailerons central) - you would feel this buffet in a full size aircraft but for a model you have to feel this point visually from the ground. Easing off the elevator input on entry to the loop as the G comes on helps here then backing off further to neutral as the model is at the top, then reapplying on the way down - this is a gradual movement of the elevator and should scribe a circle instead of an egg shaped loop. Rob
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Repair of crashed model
Rob Ashley replied to Mike Etheridge 1's topic in Building from Traditional Kits and Plans
Nicely done Mike - she looks great and raring to get airborne. Rob -
True Piers - it's like the Severn Bridge, as soon as you finish painting it you need to start over again. Did manage a flying session on Sat in glorious sunshine - would have been a good say for initial test flights on the GTC. Not ready just yet but not long now though. Finally got around to the undercarriage. Like a lemon I drilled vertically through the 1/4 ply for 2 inches to receive the UC legs instead of making a slot and making life much easier - hey ho I'm still pleased I managed that accuracy. Legs are shaped with aerofoil section over them and ready for painting. Another job off the list.
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Tim, Peter, Sorry to hear about your losses - especially from two great flying models. I hope you can rebuild them both. Best, Rob
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I say finish there's still the guttering, electrics, windows, door, insulation etc etc. But it looks like a good flying day today so hopefully I can blow the dust off a plane or two.
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Hi Piers, sorry I've not replied earlier I have been trying to finish the extension. Yes I have quite a bit of celotex left over from the house build so will be using that.
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Robert, Well done on your first build! She looks great and you have done a great job. It is a fabulous moment when something you have built takes to the air. If you are not confident to test fly perhaps get a mate who is more comfortable on the sticks to test her - this might calm your nerves too. Best of luck with the first flight and fingers crossed for you. Rob
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Man you are catching me up quick.. Nice build too..
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Levanter, Sorry missed the last part of your post about covering. I have bought some bright yellow and navy blue Oracover so I was going to emulate Peter's original with top of wings in yellow but with blue underneath then have yellow triangles on the underneath LE of main wing and tail with the opposite in navy blue on top LEs . I think I have just confused myself. Basically copying Peter's but with the 'teeth' on the LE on top and bottom on main wing and tail. As for size - I'm sure yours will have as much growl as the larger versions. Rob
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Ok so no model stuff today but as it wasn't raining for the first time in 11 days I thought I crack on with the workshop extension. A wasted 5.5ft x 12 ft at the back of the current building seemed, well - a waste so floor down and with some help from the kids framing too. A full day of work and the floor and framework is almost complete. I need to add a window and then clad with shiplap. If the weather holds - it is the UK and spring right so it's likely to rain - I will complete tomorrow so I can get back to the GTC.
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Levanter, True - but I CNC'd the frames of my nacelles so it was really the task of taking off the ply nose ring and adjusting to suit the elec motors, then filling in the side where the engine would have been and placing a hatch underneath for access to the elec motor. I am also going to add a scoop on top with the air flowing through the nacelle, over the motor, ESC and battery then exiting through the rear of the nacelle. Looking at the photo it does look like the dowel is small. It is an 8mm hardwood dowel. I tested a few different sizes a year or two back and with this I can pull 80 kg before it deforms but couldn't snap it. Oddly my tests showed I can use a single 1/4 in size dowel on this model and with my anticipated AUM it will shear at approx. 25G - way more than the wing will stand - hopefully one would only record this high level of G during a crash.... Rob
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Hi Piers, I swapped to electric because the engines I was using (OS 32 SXs) stripped their chrome cylinder linings. Alas they are not available anymore so I used that as an excuse to change this plane to electric. I fully admit I know nothing about electric, so after some research and a lot of head scratching I bought some Turnigy D3536/8 1000kv motors and 60Amp ESCs. I calculated that with my anticipated AUM (plus a little) these would provide 120 watts per lb which should be more than enough power. I know Tim Ballinger's GTC flies very nicely on less watts/lb so I think/hope I have got it right. Best, Rob
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I guess I felt guilty that Levanter was catching up rapidly and needed the motivation...?
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OK so it's been a while since any work was done on my GTC, but I have completed some projects in the house, made some retracts for a HE111 and designed & started to build a delta with my son...Oh and replaced an engine in a mates model too. I have finally made some progress with the nacelles - for some reason it was one of those jobs that I just didn't want to face - don't know why. I guess because of the late stage change from IC to elec and the alterations needed to fit the battery, ESC and motor into where the fuel tank and engine were originally. It was simple really and as I say I don't know why I didn't want to do it. They look a little square and need some TLC with the sanding block but at least the project is moving forward.
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Tim. Many congrats mate. Very pleased for you and glad to hear the GTC flew brilliantly. Interesting to note your comments about the power available too. Best Rob
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Well not much progress for a couple of weeks. I have bitten the bullet and changed to electric motors after much deliberation. Problem was my firewalls were cut for IC motor mounts so looked like this: Still complete with hole for needle valve. After a little thought, and as I had the holes and F1 already drawn in CAD, I re-drew another F1 to accept the X shaped electric motor mount. Next problem was the standoffs. I had to wait a while for the 70mm M3 screws to arrive and source some alu tube of the right inside diameter. End result was this: I can now bolt this to the original firewall using the IC T nuts and holes which should allow access/servicing. The standoffs were cut on the bandsaw, with careful sanding and electronic Vernier gauge I could get them to within 0.05 mm of each other. Took some time but I am happy with the results.
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