Tim Cheal

Hi All I have just about finished my Brain Taylor Mk 1 Spitfire, but a couple of things surprised me. First, the model needed about 1 1/2 pounds of lead in the nose to get it to balance at the CofG on the plans. The other thing that has caught me out is the tendency to tip on its nose during my initial taxi trials. The grass is really soggy at the moment, but if anybody has any experience of the CofG of this BT Spitfire Mk 1 I would be really grateful. I am tempted to ease it back a bit, but don't want to do that until after a successful maiden! Comments grateful received. Tim

Hi Nigel Apologies for being so quiet, but your build looks great to me! I have got mine ready for flying, and one thing I was not quite ready for was how much weight I would need in the front to achieve the CofG recommended. I have put just over a lb of lead in the nose now, which means the flying weight has gone up form 101/2 lb to just about 12lb. Picture below: I know you are not going to fly yours, but the other thing that has caught me out is the tendency to tip on its nose during my initial taxi trials. The grass is really soggy at the moment, so I shan't panic until the ground has dried out a bit, but that puts the maiden back until spring I suspect. If anybody 'watching' has any experience of the CofG of this BT Spifire Mk 1 I wood be really grateful, I am tempted to ease it back a bit, but don't want to do that until after a successful maiden! I am pleased with the engine installation (pumped OS91FS with a Keleo exhaust) and the 3D printed exhausts that I sourced off the internet. But, it means the exhaust is from the actual exhaust pipes - I know, little things please little minds!! The prop is only a 13 inch and is now replaced with a 14 X 6, but I had some trouble initially getting the RPM to something decent so stepped down a bit. Hoping to use a 14 X 8 when all is said and done. You can see I had to split the cowl across the middle horizontally to get it all set up, but that has not been an issue (so far!). Cant wait to fly it, but patience is the name of the game. Good luck with the rest of your build. Tim

How about an off the wall thought? I am making this up as I go along, but I had a similar problem high revving problem about 40 years ago with an HB40 (left the hobby for 35 years though) which I never resolved. So, don't shoot me down, just throwing a thought into the mix....... We use the exhaust pressure, presumably because the exhaust outlet is smaller than the inlet which ensures some positive pressure in the exhaust itself. Now, obviously there is flow through the exhaust, and it will vary with RPM. What if, at the point of the exhaust nipple, there was a flow past the nipple at a local speed faster than elsewhere, maybe a baffle is missing or has shifted inside, or something about the nipple placement on a non standard exhaust (not sure if yours is the standard one or not). as the RPM increases the flow increases, and at high revs instead of providing a positive pressure it induces a negative pressure (akin to the carburetor intake) and instead of pressurising the tank at high revs it is sucking pressure out of the tank, causing a reduced fuel flow at high RPM. Like I said, its a bit off the wall, but is it plausible? Battle armour fitted awaiting the inevitable....... Tim

BTW here'ss a link to the site I got that picture from if it is of any use? **LINK** Tim

Danny's comments are exactly what happened to me - worse, in fact, as I initially tried to make the flaps in one piece. They worked, but the bending of the wing was probably going to change the lift more than the deflection of the flaps! So, a bit of fettling in the appropriate place to split the flaps as per the plan and all is well. I haven't captured the "gull wing" effect at all though. Following my build I found this rather good picture which shows the effect rather nicely. I ran my engine yesterday with the fuel tank and all the plumbing installed, CofG next! Tim

Well, not lazy, but in compliance with aerial etiquette. Imagine the flag was flying at the rear of a ship, from one side (in the case of a ship and aviation the port side) it would appear normal, from the other side it would appear reversed. You don't very often see the starboard side of your passenger airliner, but the flag is reversed as well. I am not that sad really, I was asked by a passenger once (who had unusually boarded on the Starboard side) why the Union Flag was flying backwards as it was bad luck. After a bit of research I discovered the previous information. You won't look at aircraft markings the same again! Happy Christmas to all. Tim.

Hi Nigel I spotted this post a few weeks ago, but have not had chance to get around to replying. Rather spookily I built a Dennis Bryant Chipmunk about 3 years ago - thats my avatar. Sadly, I had a bit of a prang early on when the battery lead disconnected in flight and all control was lost. I rebuilt it from the damage - mostly to the wings - but it never flew as nice as the first couple of flights. The relevance of all this is that I am now nearing completion of the Brian Taylor Mk 1 Spitfire. It has taken me nearly 18 months, but it is more of a slow burn than a rush job. I am modelling mine on Spitfire Mk 1 N3200 (some may refer to this as Guy Martins Spitfire after the TV programme). I have it all built up and pointed, I just need to work on the exhausts and then fit all the ancillaries (cockpit, tailwheel and refit the retracts). I have found that you need to stand back and use a little intuition on occasion, particular areas where I have deviated from the plan are around the tail and the retract mounts. The bottom of the tail I have made a removable section on the, mostly to incorporate a steerable tailwheel and allow access to the control runs at the back end. The retracts I wanted to beef up (apologies to Mr Taylor but I fly off grass and I didn't want them to detach at the first opportunity - and yes I do realise that a broken undercarriage is better than a broken wing, and I haven't flown it yet to see how it works!!). I found one of the most tricky aspects has been getting the relationship between the retract, the retracted position of the wheels and some Toe In for the tracking - I still have to fettle with this some more. I also deviated form the plan on the wing mounting, which I simplified somewhat from BTs method, using dowels on the front and 2 wing bolts at the back. I used an aileron servo in each wing, but retained a central servo for the flaps, which I used LIPO and ply for as per the plan. ​I will try and put some photos on here shortly. I have used Poly C and fibreglass cloth for the wings and fuselage and then painted with Umbral rattle cans in the scene of N3200 - one of the reasons I chose this scheme is that it has a black and white underside to give me plenty of contrast when flying it. I really can't tell you much more, but as I have yet to 'final assemble' I am not really sure what the final weight and CofG will be, but hopefully more progress will be made over the Christmas break. I hope you are continuing to progress. Tim.

Wow, bugger the landing lights - which are indeed impressive - but what about that sound. Marvellous... Tim

Thanks Bob and Peter, all agreed - I just wish I could do it! I followed your thread on the aerobatics thank you Peter, and throughly enjoyed it, I should have re-read it before posting my comments above. To be fair my model dived vertically into the ground, I was very young and couldn't afford much in terms of equipment, so I was never sure if the wings had come adrift or one of my "Gem" servos had jammed. Tim

This may help if you haven't seen it before: **LINK** (I use JR 591 with a 5 cell NiMh and haven't had any problems, but I guess it depends). Tim

continued.... Now imagine this in our outside loop (a manoeuvre I have always known as a ’bunt’ but other readers have different definitions for this). If we start at the top and push (as required in the B test, and hence I believe this is the more more routine way of starting the outside loop) then gravity initially helps our aircraft nose to drop, but as our nose drops we need to increase the G to counter the affect of gravity now starting to work against our direction of turn we need extra MINUS G to keep the aircraft ‘bunting’ (we are using the same principle as the loop, and the highest G will be needed at the bottom of the manoeuvre when the aircraft is inverted). We may also be experiencing an increase in airspeed, and to maintain the ‘bunt’ we would need to increase elevator input even more (push more). There comes a point where structurally we simply can’t continue, and I suspect this is where our wings have decided to part company in the past (and in one model many years ago it caused quite a hole in the ground!). Hence, whilst I agree with the points already raised for the most part, there is definitely a difference between an inside and an outside loop, especially when the outside loop is started from the top. However, if we invert and push our way around the manoeuvre (as suggested by some others) we need the maximum G at the bottom of the bunt to push upwards, which is at the start of the manoeuvre the G reduces and gravity helps us over the top of the bunt, and when we return to inverted we should need no more push than already used to start the manoeuvre. Altogether a much less stressful manoeuvre in every sense! So, my thoughts are, you need to start the inside loop by using less elevator input, or from a faster speed and pull less, or probably a combination of the 2. For outside loops try starting from inverted and pushing upwards initially. This will give you much more confidence in the ability to control the most hairy part, where the aircraft is accelerating towards the ground and approaching the inverted. Sorry if that is repetitive in places!

The Loop I am sorry to come back to this topic, but have pondered this from the sidelines up until now and although I wrote this some days ago my computer has been upset about something and running i..n..c..r..e..d...a..b..l...y slow. You originally asked: I can do a loop but only on a small tight radius. Can anyone offer advice on how to do a relatively slow and wide radius loop, both inside and outside loops. The simple answer is ‘don’t pull so hard’, or fly faster and pull the same amount, but this would miss some important detail. About 2 years ago (January 13 issue I think, but I apparently don’t have access to the digital archives anymore) Shahid Banglawala explained how to fly a loop. In it he talks about pulling up and then starting to ‘push’ over the top. I have to say I was more than a little surprised; as an ex RAF pilot, and having taught aerobatics as an RAF QFI for many years the last thing you do on a loop is push. The loop is a positive G manoeuvre. But here I needed to back down and think about the objectives. The loop, as flown by full size aircraft is most usually an egg shape, witness the heart formed by the Red Arrows when flying opposing loops from the same starting point. However, the objective of RC aircraft loops is to fly as close to a circle as possible, and this requires a different skill. But first we need to consider what makes our loops egg shaped if left to their own devices. Of course, our RC aircraft will possibly slow down as we climb the loop which will change our control effectiveness and radius of turn. But more significantly we need to think about the effect of gravity on out manoeuvre. If we are the right way up (at the start of our looping manoeuvre) our aircraft will be subject to 1G, acting vertically down through our aircraft. To pull our nose upwards we need to increase the angle of attack (pull the stick back), and this in turn increases the G being felt on the airframe. Typically, on a full size aircraft, you need about 4G during the start of the loop. More pull, and you get a tighter radius (OK, this is limited by available lift and/or G, but lets assume this is the case for the time being), less pull, and you get a larger radius (so in theory this answers part of your question). So far so good, but our 4G pull is made up of 1G already acting on the aircraft, so we are, in effect, using only 3G to turn the aircraft. Now consider our aircraft at the top of the loop. We still have our 1G acting vertically downwards in relation to the real world, but this is now pulling our aircraft around the loop and pulling our aircraft down in the direction we want to pull, in fact to fly level upside down we need MINUS 1 G, so in fact the 1G being provided vertically downwards is effectively 2 G (the difference between MINUS 1 and 1 is 2). If we can sustain our 4G pull all the way around our loop, we would have in effect 3G turning us as we start the loop, and 5G turning us at the top of the loop. This is known as the combat egg, and fighter pilots use this effective increase in turning performance to great effect to increase their manoeuvrability. So, to fly our round loop, at constant airspeed, we would need to reduce the pull over the top of our loop. This effect is somewhat compensated for in real aircraft by variations in airspeed, but our model will also be affected. So, as we loop our aircraft the amount of pull we require reduces to keep our loop round, and then increases again as we return to the right way up at the bottom of the loop. Continued below.......

Awesome. I really hope you can get this to work (I am an ex RAF Harrier pilot). I am watching with great interest, please do keep us up to date. Tim

I have had this happen in the past. Despite checking my connections many times I had inserted the power lead in the wrong way round. I turned it 180 degrees and all worked fine It's worth a check!! Tim

Fascinating. Thanks for the heads up Alan, I could waste hours on that site!! Tim

Thanks Dom. Actually passed my B on Friday(!) so looking to extend my aerobatics a bit more.

Thanks Dom I should of course have credited your excellent video, which is most informative and realised that you had more experience than the initial video. Have you flown it in any decent wind yet (say 15mph)? Tim

Hi Guys I am thinking of buying one of these, has anybody got one that can comment on the durability and performance? I fly from grass strips and am particularly interested in the undercarriage resilience. I would also like to extend my aerobatic repertoire, and I know a pattern aerobatic plane may be better; I did have a Groovy 50 3A that I enjoyed, but was looking for something a bit different. Comments gratefully received. Tim

Great Video Dom. I was there today, and left with most others as the rain started at 1530. I have to say the show is much better on your video as you seem to have managed to get rid of the ramblings of DB sound..... I don't wish to sound unfair, but I was hoping to be informed about the models being flown and perhaps some of the Cosford flyovers that occurred. The Typhoon (or was it a Tornado) didn't materialise, but all I know about it is that it flies at 1320mph its a canard and it cost £60 million. Now, I know that its a front line fighter, single seat, very capable, used all over Europe and exported outside of the UK, but surely we could ask DB to pass on a little more facts. I learned more about fathers day and Brietling watches! But, it is a good job I don't work for Brietling (and no, I don't own one but I have plenty of friends who do) as I would have been most disappointed on DBs opinion of them; they have been great supporters of aviation over the years! I think the fare paying public deserve a better commentary than Weston Park presently offer. Tim

Whoops, a 2 minute delay!! The video is awesome....