Pete Rieden

I've sent this as a PM as well because the last two attempts to post it here failed!   ------------------ I don't think the galaxy typhoon is the same kit - the stein warbirds are imported into the UK by Phil Craft at Fighter Aces (www.fighteraces.co.uk - look under "small scale kits") and if you email him he may be able to answer your question if he has one of the Typhoons in stock that he can look at. I hyave one of the Typhoon kits (it's probably next in the building queue) and I would pop out to the workshop to look at the instructions for you if it wasn't persisting down with rain at the moment (perhaps tomorrow!).   There are quite a few threads on these kits on RCGroups, and I think one of the typhoon ones discusses CG positions; search RCGroups for "stein warbired typhoon" or similar to find them. The Americans tend to build them very heavy, with lots of glass skinning, vast amounts of filler and paint, and usually flaps/retracts as well. They seem to get them up to the 6lb mark(!) and then complain that they are tip-stally at low speed. At lower weights (3-4lbs) I gather they're fine.   PDR

I think you'd struggle with a 4s setup, mainly because it's a big, draggy model but also possibly because getting it down to 6lbs might be a bit optimistic. I'd go for a bigger power reserve (which will mean longer durations if you find that it does fly on less power), and I'd look at something equivalent to the Axi 4120/18 on 5s and a 15-16" prop, or 6s on a 14" prop.  Although I personally prefer the "quality" motors, there are several "budget" 500rpm/volt, 50-60A motors from the usual suppliers that will serve just as well. You'll need a speed controller that will handle 50A for short periods, which means a 50A "blue chip" ESC or a minimum of 70-80A in the budget brands. On a 5-6s setup you'd normally use an "opto" controller with an external BEC or separate receiver battery, although some of the more recent ESCs have a switched-mode BEC that would also work (depending on how many servos you're using). 6s would be easier simply because you could get a pair of relatively cheap 3s3000ish packs (like the Loong Max ones) and connect them in series. these packs could then be used individually in 300-400w sports models, which takes the sting off the investment. The packs could be charged individually or charged as a pair using one of the many balance lead adaptors which plug into a 6s balance socket and split it into two 3s balancer plugs. £0.02 supplied, PDR

The only useful reason I can think of for discharging lipos is for storage, and even that only needs to take 15-20% out of the cells to get them down to below 3.9v. The most effective way to do this is simply to plug them into the model they're normally used in, wander out into the back gardern and run the motor for a minutes or two. You could even do this indoors, but the revolving prop indoors is a tad risky and the draught can blow things around...   PDR

True enough, but most of these ESCs were bought many years ago when there were no "cheap" options - and as they're still going I have no need to consider replacing them. So for me they are excellent VFM, although I can see that the decision isn't as clear cut for someone looking to buy new ones today.   PDR

Almost all my ESCs are Jeti or Hacker. They are worked hard - at or slightly over their stated ratings. Many are over 5 years old and most have more than 100 flights on them (some more than 500) and I have yet to suffer any problems with any of them. I have a Modelmotors 55A Opto ESC that is six years old and has over 200 flights on it - still going strong.   In fact the only ESCs I have ever had any grief with were both Castle Creations Phoenix 25s. The first one burned out running at 19A, and the second (sent as a replacement for the first0 did exactly the same. So I obtained a refund and replaced it with a Jeti 30A one which has behaved faultlessly ever since.   PDR

Posted by Alex Leigh on 23/06/2009 09:41:01: After my ESC caught fire, I was looking for a replacement, and was reading on a website that the recommendation is 50% headroom. So if your motor draws 28a (as mine does with the standard prop), should I be buying a 40A ESC rather than a 30?      In my experience this is a "you get what you pay for" thing. Almost all of my ESCs are Jeti or Hacker (which are mostly the same hardware with different software). I routinely run these at or slightly above their stated ratings at full throttle - for example I run my Jeti Advance 40-3p controllers at between 40 and 45 Amps because that's what their specifications state they can achieve. Several of these are over 5 years old and have over 500 flights on them, and they are still going strong. I actually use the over-current protection of the ESC to protect the batteries. Likewise my 18A ESCs are run at 18-20A and my 12A ones are run at up to 14A. I have an ancient Modelmotors 55A Opto ESC that spends most of its time at 60-65A (but only for bursts, because it's used in a hotliner).   Now I've read this theory put out by the cheaper suppliers that to run at 40Amps you need a 60 Amp ESC (actually an ESC whose advertised rating is "60 Amps continuous, 90 Amps burst") and as far as I'm concerned that simply means they lied about the ratings. If it can't take 40Amps then it's not a 40Amp ESC. But I can understand the temptation to buy the cheap stuff and tollerate the snake-oil in the instructions!   £0.03 supplied,   PDR

The video is a clip from the Icarus Aerofly Pro Deluxe RC simulator. That Harrier is one of the satndard library of aircraft that comes with the sim - I have it here on mine. The scenery is one of the standard AFBD locations.   "I reckon you would need a second fan  rotating in the opposite direction to the first to counter act the torque from the first (just like the real deal), when it's vectored downwards. "   The spools contra-rotate in the Pegasus to cancel out the gyroscopic moments rather than torque. This was done after the lessons Bill Bedford learned when flying (and crashing) the X-14.   The biggest problem with doing a model harrier isn't power or thrust - to achieve safe VTOL operation requires a thrust-weight ratio of around 1.3 to 1.5:1 and this is relatively easily achieved with today's lightweight RC and power systems (even electric). The problem is control. The full size Harrier taps approximately 10% of the engine thrust into the reaction control system (the "puffer jets"), but it has a lot of inertia damping. A few sums have suggested that a typical model size - (say 36" span and weighing around 4lbs) would need to have about 1.5lbs of reaction control thrust available to give it fast enough control authority during the transition, and about 2/3rds of this just at the hover.   Even if you could create that sort of thust through the small sized pipes and nozzles that would fit in the airframe (which is doubtful) the total power and weight requirements would become impractical. You'd also need a very good gyro on the rudder during transition from normal flight back to the hover - this bit bites quite badly on most full-size VSTOL aircraft.   PDR

Though I think the way things were done politically remains in many peoples memories and many feel it was a major nail in the coffin of our aerospace industry.   Perhaps, but a dose of realism is also required. A military aircraft industry requires a home market (it's almost impossible to sell a military aircraft overseas if it hasn't been bought locally for a number of technical, regulatory and political reasons). Military aircraft programmes are EXTREMELY expensive - even the USA couldn't afford to develop the JSF without overseas partners.   If you look back to the UK in the 50s and 60s the place wasn't exactly brimming over with cash. The UK's only hope of funding a full TSR2 programme was to sell to "home" markets like Australia, Canada and South Africa. The technical troubles put the foirst two off, and the third was about to become an international pariah for 40 years. The last full-indiginous military aeroplane developed in the UK would be the Hawk, and that was only possible because it was felt (rightly, fortunately) that there would be a significant export market. The Sea Harrier was the last fully indiginous war-fighter, but it was only possible because it lwas on the back of the largely US-funded P1127/Kestral programme (MDF funding).   As for civil aviation yes, there were some bad decisions (like letting BEA wreck the Trident specification) but even changing these would only have extended things by a year or two IMHO. The USA would never have built the post-war airline boom with anything but american-built aircraft no matter what we did. Even now where there is a demonstrable technical/financial advantage the take-up of Airbus products in the US is disappointing.   I suspect it is probably truer to say that the UK's aviation industry was unsupportably large, and needed to shrink to fit the domestic pocket.   PDR

I do believe the TSR2 would have been a fine system, if the avionic concepts were to demanding, they just needed to be ammended to the do able.   Well if the avionic requirements were descoped to that extent you'd lose the low-level strike capability, and that was responsible for around 80% of the basic configiration decisions. So what you'd end up with would be an over-sized and very expensive air vehicle with around half the mission capability of the Tornado GR1 (let alone the GR4). So I'm not sure what your definition of a "fine system" would be!   PDR

I've often thought it could be veery interesting if each driver/car was given a fixed fuel budget FOR THE SEASON. Could make for some interesting races in the second half of the year, and could also allow a car to get some benefit of it went offthe track (or blew an engine) in an earlier race...   PDR

The history is all out there for those who ant to look, but people prefer the myths to the reality because it gioves them someone to blame (much like the present focus on bankers rather than the people who had five times their salaries in credit-card debt!). I have the advantage of 20 years in the military aircraft industry. but that just helps me know where to look.   A good place to start (and an interesting read) is "Project Cancelled" by Derek Wood.   PDR

Did TSR2 stand for anything   TSR is the standard RAF nomenclature designating the role (Tactical Strike Recon, meaning photo and radar recce, conventional bombing and nuclear), the "2" being a mater of convenience. If it had enetered service it would have been given a name - I understand the smart money was on "Python", so its full designation  would have been the "Python TSR2".   Were the engines used in other aircraft   The engines were Olympuses. Various forms of these were subsequently used in the Vulcan (without afterburner), Concorde (with afterburner), various military ships and numerous turbogenerator sets and turbo pump sustems (I believe the Athabasca oil pipeline uses several dozen Olympus-based pumps).   Were any of the TSR2 designs used in any other aircraft   Various elements of the TSR2 avionics system were used in many subsequent programmes including the Jaguar and Harrier GR1-3.   I understand a lot of the design team went to america, Not as far as I know. The airframe teams were the BAC teams at Weybridge and Warton, whilst the avionics work was done by people form dozens of companies. All simply moved on to the next project. Did anything come out of America resembling the TSR2?   Not really - the americans weren't really into very long-range, low-level tactical aircraft. The nearest would be the TFX (F-111), but it's not really addressing the same functional requirement.   PDR

It's not just the "wake" behind the blade that's disturbed; the passage of the blade will influence the air for a long distance above the blade, just like the wings of a biplane (and the reason for staggering the wings of biplanes).   But the ussue of efficiency is more a matter of aspect ratio. the lower the net aspect ratio the more drag is generated for a given amount of lift (this ois phundamental fizicks, and can't be overcome with clever design). A three-blade prop has two-thirds of the aspect ratio of an equivilent 2-blade one. This could be compensated by reducing the chord of the blades, but then the blades would be operating at lower Reynolds numbers and (again) efficiency would drop.   Prop design is a complex but well documented subject, but a reasonable rule of thumb is that the most efficient prop is a single-blade one which is just large enough for the tip to be running at around Mach 0.6 with the desired power. But single-blade props place extreme stresses on the hub, and a safer option is to take a small penalty by having two blades that just achieve M0.6 at the tip for the required power. If you need to use mopre power then you must (reluctantly) use more blades, but more b;ades is always worse than fewer blades.   PDR

Bit of trivia....did you know?......oxidation does not mean "to combine with oxygen"   According to the textbook on my shelf oxidation is defined as: "The addition of oxygen, the removal of hydrogen or the removal of electrons". Reduction is defined as "The removal of oxygen, the addition of hydrogen or the addition of electrons".   PDR

"Incidentally, Two-strokes, being pressure charged, cannot be supercharged unless the porting is changed so that the exhaust port closes before the inlet."   Hmmm...yes and no. It's certainly difficult to use positive-displacement superchargers with 2-strokes, but most high-performance twostrokes are actually supercharged (even in model aircraft use). They use a mechanically very simple pressure-wave supercharger which we more commonly refer to as a tuned pipe.   PDR

What size prop were you using? A 3800rpm/volt motor on 3 cells would normally need a pretty small prop or a fan.   PDR

You BUY balsawood?   PROPER modellers grow their own from seed...   PDR

You *buy* balsawood??   PROPER modellers grow their own from seed...   PDR

Ah. I assumed it was an officer's mess, with a bar and a stewerd....   PDR

I was looking at the one in Cosford back in November (we use the "bunker" in the cold war hangar as a conference facility every year). As one whose day job involves trying to squeeze ever more capability into every nook and cranny of the Harrier I was extremely envious of the main avionics bay. I could get a whole avionic DESIGN TEAM in that space - it's probably larger than my office!!   PDR

TSR-2 was abandonned because the aircraft systems integration task was beyond the technology of the day. You'll find the story documented in many places, but for a full blow-by-blow account I recommend "project Cancelled" by Derek Wood. The entire operational concept of TSR2 hinged on two things - the ability to travel for long distances at low level at Mach 1.2, and the use of a fully-integrated nav-attack system. The drag numbers came out too high for the former, and the integrated nav-attack system was always just a pipe-dream. Having seen the design requirements documents for what they were trying to achieve I have to say it's something that we wouldn't consider a trivial task with *today's* technology and experience. 45 years ago the understanding of systems engineering science just didn't exist, and the data-processing hardware wasn't even vaguely up to the task - they'd bitten of so much more than they could chew that they didn't even appreciate how unachievable their design goals were until just before the programme was cancelled. The airframe flew, and the flight systems worked, but without the low-level range and integrated nav-attack system is was just another fast jet bomber - too big for tactical work and with insufficient weapons stations for medium-level bombing. The imaginative video shown above shows the aircraft with multiple weapons stations on the wing. Even if the structure had been redesigned to accomodate these the resulting drag numbers with external stores would have dropped the range even further and probably essentially removed the supersonic capabilities altogether (as happened with the B1-B). The programme was NOT a wasted effort though. Pretty well all the British military aircraft that followed used elements of the nav-attack system, including the Jag and the Harriers GR1-3. The lessons learned on systems engineering were applied to all subsequent projects, and the fundamental lesson (don't try to spread the work around too many companies and locations for political reasons) was identified, although not fully acknowledged and implemented until after the Nimrod AEW fiasco. £0.05 supplied, PDR

  Takes me back to my 3rd yr engineering project (long while ago ) which was to look at effect of varying inlet tract length on a two stroke engine (MZ250 ) and plot the harmonics etc. After the test I checked the original air box and sure enough the inlet duct was the same length as the one that I had shown gave the max benefit. Get the wrong length and you will lower the pressure at the inlet port/valve just as it is opening having a negative effect.   Now that has just given me a serious attack of deja vu!   Frank - were you ever in the woking club, or others in the surry/hants area? I have a feeling we may have met back in the late 70s or early 80s   PDR

As expained exhaustively in the earlier posts, a gust that reduces the airspeed of a wing won't stall it.   PDR

Delft University have done quite a lot of work on low-Re aerodynamics, but one 6thing that comes out is that at the very low Re and Mach numbers the air is so "sticky"  that the difference between "usable" and "optimum" is much smaller than at higher numbers.   For this competition - were you allowed to gear the engine down to allow a usable prop to be driven with the engine nearer to its peak power? The stock Irvine 40 peaks on something like an 9-6 prop, which would be unsuited to the application, and a more suitable prop would see the engine producing probably no more than 60% of its peak output...   PDR

True, but it was 1973-77 as an air cadet, and then from 77-79 as a PPL (thanks to an air cadet flying scholarship) scrounging flights with AEF 6 at RAF Abingdon. I later flew the Bulldogs with the UAS, but personally I prefered the Chipmunks. PDR