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Piers Bowlan

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Everything posted by Piers Bowlan

  1. You showed us the air scoop you fitted Bonzo but where is the exit for the cooling air? The opening for the exit should be larger than the intake to ensure a cooling flow of air to the ESC and battery. I think most modellers use an ESC rated at least 25% more than the measured current draw (by a watt meter). I guess it doesn’t matter too much with a light-weight cheap foamy.
  2. Miss Lizzy at 51in span is a good size, me thinks. It has been on my build list for an electric conversion since Sep 2005 when the plan came out! A glaring omission by Sarik not to offer a parts set. Still, no biggy cutting out a set of parts oneself. Perhaps RCM&E should republish the plan in a future issue with a leccy conversion? Get well soon Peter, the modelling world is waiting for your next design. 😊
  3. Why did you put your plug in the oven? I heated my plastic sheet held in its frame in the oven until it sagged (wife was out!) I switched on the vacuum cleaner and smartly pulled the frame holding the plastic over the plug. The plastic cooled very quickly once formed on the cold plug, so didn’t have time to damage the dope finish.
  4. I made a plug for my Blackburn Firebrand out of balsa laminations as it is quick and easy to shape but not cheap 😢. I gave it several coats of dope which gave a good smooth finish after sanding. I mounted it on a balsa spacer for the vac- forming.
  5. The wooden block is end-grain which doesn’t glue particularly well. The front screw is countersunk, so more likely to pull through liteply. Also, a bigger doubler that extends to the top will help those who havn’t started yet. I will try a roundhead screw and large washer as well. I appreciate the rear screw needs to be countersunk because of the hatch. This non-issue doesn’t seem unresolvable, it’s just engineering.🤔
  6. Hi Mike, I expect you have checked already but as these engines seem to like plenty of oil (22%) - particularly castor, is the crankcase vent clear of fuel gunk. Also checking the pressure line from the muffler is clear, could be worthwhile. Hope you get it sorted 👍
  7. Published thrust values for motors are usually just a guide to what the maximum thrust might be. The number of cells used (voltage) and the load (Amps) prop size (diameter and pitch) will both massively affect the power of the motor (Watts). The prop efficiency will be a factor too, which brand of prop- Master Airscrew or APC for instance. Then, what thrust are you talking about as static thrust will tend to be less than dynamic thrust, when the motor unwinds in the air, as it won’t be partially stalled as it is on the ground. The limiting factor for a motor is at what point does it become inefficient and start turning more power into heat which ultimately will end up burning out the windings? In short, the right motor choice for a model is not always clear cut!
  8. ‘Vertical flight with an airspeed above stall is still low alpha, or pre stall.’ If an aircraft is in vertical flight it may have zero alpha (no angle of attack) as the wing won’t be producing lift it won’t be stalled, the aircraft hanging on the prop (vectored thrust). So not too sure what you are driving at here or what you are trying to achieve? Why the interest in a model’s stalling speed and its relevance to power requirement? As I understand it, you want to know what the minimum power requirement is for your trainer?
  9. ‘I was curious what the minimum pre drag power requirements would be if you wanted to maintain a slow speed straight up without looking speed just based on the rate of potential energy rate increase.’ 😳 Would you mind explaining what any of this means please?
  10. A few images of my Firebrand in-build showing the CF reinforcement.
  11. In March 2022 the PSSA hosted a ‘48h build challenge’ using a single sheet of foam (board) and balsa, the plan to complete the models in 48 hours! I decided to use expanded polystyrene foam sheet instead from B & Q and the model subject was the Blackburn Firebrand. Long story short, I made a simple bow out of wood connected to a cheap power supply from eBay. The cutting profiles were thin ply with the edges hardens with cyano, then sanded smooth. My whole approach was low-tech and after several attempts achieved passable results. Slight ridges could be sanded smooth with fine sandpaper. Wings and fuselage were reinforced with carbon fibre strips let into the foam. Once covered in brown paper and PVA the wings were surprisingly strong and rigid. Other non-model related projects intervened and the model is now finished but primed, ready for painting.
  12. A Daily Telegraph article claimed EV tyres would only last 7500 miles! More EV bashing by the DT!
  13. I wouldn’t rely too much on seeking clarity regarding the EV database website you linked to Grumpy. There are several items there regarding my Nissan Leaf Tekna e-Plus for instance, that are not correct. I suspect the same may be true for most of the EVs on the list. The trouble is these cars are evolving so rapidly the data becomes out of date as soon as it is posted. As far as speculating on what any government might do in the future regarding taxation, that is a pretty futile exercise in my view and be incidental compared with the savings you will make on the cost of petrol/diesel. The cost of running any car will inevitably go up. My insurance premium on my diesel LR Discovery is eye watering compared with my Leaf 🥲. As for EV tyres I have just replaced the front tyres on my Leaf after 32,000 miles. £150 for the pair. Not too bad 🙂. No doubt there are better EV cars on the road now but the thing I like best about my leaf is the driving experience. The handling is great and best of all the effortless, linear, silent acceleration that you don’t get with IC. But that is just my opinion, each to their own.
  14. Is it any more dangerous than being rear ended when you are on a bicycle?
  15. Which local authority?
  16. Keep the clarifications coming Eric. What glue are you using by the way?
  17. Looks like an interesting and straightforward aircraft to model. A smaller scale would be more my comfort zone. Good luck Carlos 👍
  18. I was an instructor at a flying school on C152s back in the early eighties. One of my charges was neither old nor stupid but seemed to have an inability to know what ‘right’ looked like. I demonstrated numerous times, as I explained and then prompted while he was carrying out an approach. He seemed incapable of assessing whether we were high of low on the approach. If we were drifting off the extended centreline he seemed reluctant to make corrective actions without continual prompting. He had had several lessons but he wasn’t really progressing in making his own decisions but happy to let the plane fly him rather the other way around. I suggested that on the next circuit I would not prompt but we would discuss how it went later. On his approach we sank lower and lower. The trees on the undershoot were looking very big and starting to obscure the runway. I asked him conversationally how he thought it was going? He didn’t know what to say. I said, ‘I have control’, applied power and climbed back onto the glide slope. I don’t know if it is fear of making things worse, or not recognising that positive input is required. There has been speculation in this thread whether it is Frans’s age, his eyesight, lack of practice or the wrong model. After breaking several aeroplanes it could be that he is in the wrong hobby and should try model boats!
  19. Had a quick rummage through the Tempest kit that arrived today (wife was out!) A very complete kit, super laser cutting, nicely drawn plan and I wish I could cut cores like that. Start next week and attempt to keep up with Ron. Well, it is good to have ambition at any rate!
  20. Good point Grumpy, but the stock FMS Beaver has a wing loading of around 21oz/squ. ft if my estimate is right (almost glider territory). Even if a layer of woven glass and epoxy were to double the weight of the cowl, at least the weight is in the right place (the nose). The thin plastic cowl is thin and plastic because it is cheap and quick to manufacture, not because it is fit for purpose. It might be interesting to weigh the cowl before and after glassing?
  21. As Jrman says, lightweight woven glass cloth cut to roughly correct size. You may need to snip several small cuts in the side of cloth nearest the front of the cowl to persuade it to follow it’s shape. Brush on lots of epoxy and stipple in. When done leave to stand (nose up) on some cellophane (or similar) to allow the xs to run out. When dry or semi-dry cut the xs cloth protruding from the back of the cowl. Don’t forget to cover the outside of the cowl with low tack masking tape or it will end up a right mess ( it is a messy job. ) I would get a piece of card and cut a round hole the same size as the cowl. Push the cowl through the hole to ensure the cowl remains perfectly circular (if it sets oval it will stay oval!!) Don't use too much hardener or it will get very hot 🥵. The glass cloth will provide a lot of split resistance but it is not indestructible. The cowl is usually the second thing to hit the ground (after the wheels🤣).
  22. It looks like a very nice model Toto, I am sure you are itching to fly it again. Going forward, in the event of a ‘non standard arrival’ should the elevator hit or scrape the ground, the tip will deflect but the root is constrained by the control horn connected to it’s servo. Result? The EPO foam elevator splits as it did before. Where the split occurs is called a ‘stress riser’ between the plastic part and the foam. Hopefully you won’t get a repeat break but you could reinforce the elevator to make this less likely. If you were to drill a couple of pilot holes and insert a couple of carbon rods inside the elevator as you did before with your repair, the elevator would be somewhat more robust. The cowl is a thing of beauty (!) but appears to be made of rather thin plastic (ABS? 🫣). In the past I have epoxy/glassed the inside of thin ABS cowls as it adds considerable strength to a vulnerable part of the model. Just be sure to mask off the outside of the cowl to avoid unsightly sticky finger prints as epoxy seems to goes everywhere. These ‘rainy day’ jobs/upgrades are quite satisfying to do and may avoid these annoying little repairs being necessary in the future. Just my 2p worth!
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