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Peter Christy

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Peter Christy last won the day on July 29 2021

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  1. I used to race Karts in the early 70s, as part of the South Devon Technical College team. Our Karts competed in Class 4 Standard - basically 200cc Villiers, which could be modified anyway you wanted internally, but had to look standard externally. If you could not exceed a ton down the main straight at Dunkeswell, you weren't competitive! We were very competitive! We had three Class 4 Karts. Two ran on Castor, the third (the one I raced) ran on mineral oil - Molybdenum Disulphide based. Ours was the only engine that did not need repeated rebuilds throughout the season. Indeed, when stripped down between seasons it rarely needed attention! Karts were designed for 10 lap sprints. At the end of the season, we had an hour long endurance race for each class. Each of our karts had a team of four drivers assigned to it. For the endurance race, we used to swap drivers at half distance (you really could not stand any more, physically!). But hold on, I hear you say, that only accounts for two drivers! Well the class above us (Class 4 International - originally 200cc anything goes, latterly 250cc anything goes) only had very few entrants, so Class 4 Standards were allowed to make the numbers up - if you survived your own class' endurance race. Our Kart finished in both endurance races (run consecutively!) every season I was there. It was the only one of our Karts that did. It was also the only one NOT running on castor oil! -- Pete
  2. Incidentally, IIRC KeilKraft Nitrex 15 used nitroETHANE rather than nitroMETHANE, which is why it smelled different. The lubricant back then would have been castor, but that was before synthetics became generally available. There is absolutely no issue running ANY glow motor on good quality pure synthetic, and there are a lot of advantages. Castor builds up both on the exterior and interior of an engine over time, especially if the engine runs in a hot environment (cowled in, or in helicopters). This does not help cooling, and the drag from the gummy residue leads to a slow but steady power loss. Synthetic may not shift the exterior residue, but it does a fair job of cleaning up the inside! All the engines that I switched to synthetic now look like new inside. Cox engines are no different. -- Pete
  3. You have missed out one important factor from the motor's specification - the wattage! Phil G (of this parish) came up with a far simpler formula than those often prescribed for calculating the desired wattage of an electric conversion, namely 100 watts per cc. (Interestingly, this formula also works for helicopters, unlike most of the others!) Your model was designed for 0.8 - 1cc motors, so around 100 watts would be ideal. Most motors in the .8-1cc range would run a 6x4 or 7x4 prop. Your motor seems to aim at an 8x6, which would normally be fitted to a 3.5cc (approx) motor. This indicates to me that your proposed motor is over the top for the model! Having said all that, one of the beauties of electric motors is that they don't seem to mind being under-propped - unlike their i/c equivalents. The maximum rpm is governed by the kV rating, provided they are not over-loaded. 1400kV on a 3s pack gives a theoretical max rpm of around 15-16,000 rpm. If you run it on a smaller prop, then that should reduce the current draw (and hence wattage) to an acceptable level. Provided the weight of the motor and battery is not excessive, and it physically fits, you should be OK. Just don't fit an 8x6 prop! Use something smaller! Maybe a 6x6 or 7x6? -- Pete
  4. To a point - a lot of printers will refuse to print it if it has a copyright symbol on it. -- Pete
  5. Looking at the size of the antennas of those jammers, I would guess that they are aimed at the higher frequencies (2.4 GHz, etc). Glad I've still got my old 35 MHz gear...... -- Pete
  6. Cox .049s don't need castor. I run mine on Bekra 16% Heli fuel, and they go like stink on it. Bekra is pure synthetic, around 18% from memory. Not had any issues running Coxs on it in over 10 years. -- Pete
  7. I only saw him a couple of months back, at the Ponty Retro do. He seemed his usual bubbly self, full of enthusiasm for everything flying. I'm truly shocked and saddened that he could have passed so quickly. RIP, Alex. -- Pete
  8. Hi Shaun, Its got the 1.5. However, it has been mildly "breathed on". It has a Weber twin choke carb on the proper S&R manifold, and a stainless steel sport twin exhaust. I did similar mods to my original one back in the early 70s, and it halved the 0-70 time, without having any effect on MPG - which tells you a lot about Ford carburettors! This one is quick by 1970s standards - about on a par with a Cortina GT, but with much better handling and roadholding! Its not particularly quick by 21st Century standards, but is more than capable of holding its own in modern traffic. Its one of the few cars I've been able to drive for hours without getting back-ache or "numb-bum" syndrome. The seats are wonderful! -- Pete
  9. @DavidDavis From 2011 to 2013 this was my daily driver! I've owned it since 2008. I drove it to Interlaken in Switzerland in 2010, and Ballenstedt in the old East Germany to attend the European Helicopter Championships in 2012. It never missed a beat on either journey: It had a full bare metal respray in 2014, and now only gets light use. It has been completely reliable the whole time I've owned it. I bought a new one back in 1969 to replace a Sunbeam Imp which had proven to be an utter disaster! Water leaked into the Sunbeam when it rained, and oil leaked out of it. It needed a new cylinder head and valve gear before it had even finished running in, as they had never been hardened properly. Rust started appearing when it was only a couple of months old, and the ignition needed re-timing weekly as the distributor clamp didn't clamp properly! The heater never worked, but the final straw was a total brake failure one night! It was only 9 months old when I traded it for the SAAB which never gave me a problem the whole 7 years I owned it. I only sold it (and it broke my heart!) when I was told in no uncertain terms, that it was no longer big enough for an expanding family! After the experience with the Sunbeam, I swore I would never again buy a British car. A decade later, I succumbed and bought a Rover SD1 2600. That proved to be even worse than the Sunbeam had been - except the brakes didn't fail on it. Indeed, I think they were the only things that didn't fail in the short time I had it.... Oh, and I still have my Bonner Digimite-8, bought second hand in 1968, and still working - though now retired from active service! So yes, some things are just as good now as they were back then! -- Pete
  10. I would build it as specified, DB knew what he was doing! I recently built a "Ghost Rider" for my Galloping Ghost equipment, and it is similar to the SkyRider. It has needed a LOT of downthrust to keep it flying straight under power. In fact, I haven't got it right yet, and at full throttle, full down elevator is insufficient to control the climb! On the glide, it is perfect with neutral trim. I should add that it really needs bigger elevators, as the elevator control is marginal. Nonetheless, there is a very marked trim change under power! -- Pete
  11. The Cardinal was rigged for a gentle glide (plenty of positive angle between the wing and tail surfaces). As the speed increases, this gives a strong "up elevator" effect. Under power, the speed will be greater than on the glide, and can lead to excessive climb angles and stalls under power. The downthrust prevents this from happening. A zero-zero rigged aerobatic model does not need downthrust - indeed in is a disadvantage as it will lead to different handling characteristics between upright and inverted flight. Sidethrust is an attempt to overcome two problems with lightweight models like the Cardinal. Under power, the torque reaction from the engine will tend to make the aircraft roll to the left. Also the "corkscrew" slipstream behind the propeller can hit the fin and rudder, causing a further left yaw effect. Offsetting the engine to the right slightly can counteract these tendencies, but you are trying to counter a roll effect (from engine torque) with a yaw function (sidethrust). On models like the Cardinal, the dihedral angle of the wings will help convert this yaw into roll. Again, on an aerobatic model with little dihedral, side thrust will have little effect and is best avoided. All these effects are far more noticeable on very lightweight models like the Cardinal. I'm not an aerodynamicist, but this is my understanding of the situation, and its stood me in good stead for several decades! -- Pete
  12. I gave up on Perry carbs years (decades?) ago! I don't dispute that they can give good results for a while, but in my experience, they are far too finickity. The plastic deteriorates, the O-rings deteriorate, they clog far too easily, the list goes on and on! I replaced mine with Kavan carbs (all metal), which while also fiddly to set up, are at least consistent once set. Kavan carbs can still be found, though I suspect they are (sadly) no longer manufactured. Irvine carbs are also excellent if you can find one to fit, though again, long out of production. -- Pete
  13. I think that applies to pretty much all JR servos! I think they did make some dedicated HV servos, but all the common ones were 4-cell only. Frankly, I've never understood this obsession with 5-cell packs. I've never used anything but 4-cells NiXX sets since the late 60s, and never experienced a problem with them. Even my early Spektrum sets never showed any inclination to "brown out". It is my belief that most of the issues that 5-cell packs were meant to overcome were down to poor quality switches and/or connectors. Over the years, I have witnessed some real horror installations...! I have ONE model that uses a 2-cell LiFe pack and high voltage servos. One of the (quite expensive!) servos failed within days of purchase. I can only recall one servo ever failing on 4.8V, and that was a retract servo. I have no idea how many servos I've had down the years (decades?!) but it must be a lot! I've got servos that are nearly 50 years old, still functioning perfectly on 4.8V. Run them on what they were designed for, not what "old wives tales" tell you you should! -- Pete
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