Piers Bowlan

Balsa is a very satisfying and versatile material to work with as we all know so well, pity it has become so pricy. I have fairly recently rediscovered the joys of hot wire cutting EPP foam sheet. With a little carbon strip (or balsa or ply) reinforcement and covered with brown paper/PVA, it is very light, torsionally stiff and surprisingly tough. Best of all it is very cheap too! You can quickly knock out several models from one sheet of 2.4x1.2m foam for under £20 from B & Q. It doesn’t require too much effort to make up a cutting bow and source a suitable power supply from eBay.

I had a catapult launched EE Lightening that flew great and was just as dangerous! Until that is, it disappeared into the soft sand on the beach I was flying from, never to be seen again. 😢 They don’t make fun toys like that anymore, wonder why?!! 🤣

Airliners like commercial shipping (and fishing boats) don’t pay UK VAT on their fuel. It’s a global market so if they did there wouldn’t be any UK airlines, or jobs. If you think the fuel should be taxed globally, tell that to ICAO. However, ‘holidaymakers that fly half way round the world for a week in the sun’ are taxed here in the UK. Air Passenger Duty raked in £4500 billion to the UK treasury last year. If air travel is to be greener then airlines need to buy more efficient aircraft, geared turbofans as one example, which is an expensive long term commitment. More taxes is just a disincentive to do that and won’t make the world a greener place. Finally, making comparisons with your diesel car is a bit fatuous for obvious reasons.

Reading the Outerzone reviews it looks like it will be an excellent model. Good luck with the build Nigel. 👍

I’ll try and make the weekend but not ‘Seven days’ (Craig David).

Why don’t you pop them an email Stuart, telling them to send you the correct sized plan and a couple of the missing formers while they are at it? They will probably be pleased to hear from you as no doubt all the kits in the recent product run are like it. I don’t believe they did it on purpose and it won’t do their reputation any good.

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.

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. 😊

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.

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.

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.🤔

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 👍

I agree PatMc, I got that wrong way round. Doh!

Fair enough 🙂

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!

‘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?

‘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?

A few images of my Firebrand in-build showing the CF reinforcement.

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.

A Daily Telegraph article claimed EV tyres would only last 7500 miles! More EV bashing by the DT!

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.

Is it any more dangerous than being rear ended when you are on a bicycle?

Which local authority?

Keep the clarifications coming Eric. What glue are you using by the way?

Looks like an interesting and straightforward aircraft to model. A smaller scale would be more my comfort zone. Good luck Carlos 👍