Colin Leighfield

Looking good! Keep going Simon,

I've started on mine. Got the wing panels planed and sanded, ready to join. Started on the fuselage. I've decided to forget the undercarriage, the encouraging indications about under-arm launching have convinced me to try it. (Challenging my nervous tendencies). I've got no problems with slithering it on the grass for landing, the Fizza's always been fine with it. Is anyone considering a dope and tissue finish? It might make some of the choices on alternative finishes easier and I can't see weight being an issue with a 1250Kv motor?

Erfolg, that's a really enterprising project. I assume that means you intend to use a pusher propeller, I can see that a ducted fan would be a struggle with this design. You could combine it with some Estes rocket motors to get it off vertically! You have my greatest respect, I've never seen a model of this one before.

Erfolg, is that a Bachem Natter I see in your photo? Have you flown it? I've got a huge block of blue foam in the loft and I recently got myself a hot wire cutter. Must give it a try.

Another one of those names that seems to have been around as long as I have been messing with model planes, back into the 50s. Didn't he do full size as well, I seem to remember him flying a Stolp Starlet? Very sad news. RIP.

I congratulate you Simon for achieving so much with Depron! A couple of years back I had a go at making a ducted fan Hawker Hunter out of Depron. There was quite a lot of sanding to shape. I confess that I gave up and binned it. The thought of Depron puts my teeth on edge, lord knows why. At some point I must stop being silly and have another go. Seeing what you've done with it makes me think and the weight advantage is obvious!

Both the plane and the Whittle by-pass engine would have been world leading. Cancellation was utter stupidity and, much as I admire him, Barnes-Wallis didn't help. The definitive work on this is the recently published "Miles M.52 - Gateway to Supersonic Flight", written by Eric Brown and co-authors. It's a compelling read.

Erfolg. You're quite right about the Me.262, the wing sweep was a solution to a cg problem and nothing to do with compressibility issues. In fact it's critical Mach number was lower than that of a Spitfire anyway, regardless of it's top speed in level flight. It wasn't much quicker either than the Heinkel 280 with similar engines and a straight wing. (It did look nicer though). Sadly the acquisition of German data on swept wings and compressibility was used as an excuse by Sir Ben Lockspeiser's committee to cancel the Miles M.52, when it was almost ready for it's first flight. They said that this information had made the M.52 obsolete and irrelevant before it flew. Complete stupidity, I don't think there's any doubt that it would have been the first aircraft to go supersonic in level flight, look at the F.104 and F.16 as evidence that there's nothing essential about swept wings! What is more the M.52 had been designed in a way that different wings could easily be adapted to the fuselage because the attachment was to a circumferential beam in the fuselage, which meant that different wings could be almost bolted on and off. I'm digressing and revealing things that make me bitter. Winkle Brown's analysis is bang on for me! Cheers!

Simon. You're quite right, when I said that there was no dihedral I was referring to the top of the wing, in fact the upward taper of the wing underside does give a degree of dihedral, I hadn't envisaged that you'd got it the other way around! I appreciate that you've achieved amazing lightness in creating this and that certainly eases hand launching, (which I'm hopeless at), but personally for that first flight I'd definitely be looking for a smooth surface to get a gentle R.O.G. and gingerly sort out any detail trimming issues. I've got total confidence that you will make this work and have a good flyer, which is more than I can say about my own confidence in the Wellesley, without even mentioning the 70" Westland Welkin waiting for the cg to be finalised. (Another story).

I chose the Typhoon deliberately Erfolg. Although Camm didn't grasp until years after Mitchell the importance of wing thickness in controlling compressibility at high Mach numbers, the one thing that the Typhoon wing was good for was load lugging at speeds far higher than the Hamilcar ever approached. To me the Hamilcar wing is an efficient design for it's purpose. It's got an aspect ratio of 8 to 1 with a wing section .that was as good as you'd get at the time, operating at speeds where the relative drag of the fuselage wouldn't have been critical. I agree with you that the tall fin is almost certainly perfectly adequate, for modelling purposes it wouldn't hurt to enlarge the tailplane and having enough thrust at take off and normal flying speeds is crucial. None of these are too difficult, this should be a good flyer. I wouldn't like to have to get my hands around it for a hand launch though, good luck Simon.

Simon/Erfolg. The Hamilcar didn't have any dihedral and I doubt if it will matter very much. I know that doubt has been cast on the quality of the drawings in Aircraft of the Fighting Powers and it is certainly true of some of the more "secret" types, but I think that most of them are of quite a high standard and I consider the Hamilcar to be in this category. Some attention had to be paid to aerodynamic efficiency at the designed operating speeds because these things had to be towable and the Hamilcar was pulled along well enough by a Halifax. As far as angle of attack is concerned, high angles would be very unlikely, in the tow position the glider is positioned well above the tow plane and the nose is level, not raised. There's no doubt that the huge flaps are designed to enable a rapid descent in a fairly sharp nose down position at a controlled air speed and giving the pilot maximum view of the landing area. Once Simon has got it flying, it should be great fun to try this out and find out how much elevator trim has to be dialled in! Tailplane blanketing at different angles of attack is one of those varying things. To me, the tailplane on he Hamilcar is on the low side for minimisation of interference effects at normal angles of attack, perhaps it would have been better higher or lower, but we need to be careful in thinking that our judgement is better than that of the guys who designed these things. As far as the wing section is concerned on the Hamilcar, the RAF 34 doesn't look very different from the NACA section on the Hawker Typhoon and it's worth remembering that the thickness/chord ratio of that at the root was over 16%, almost as thick as the Hamilcar! Stored in my garage loft I still have my Cambria Slingsby Eagle, 70" span, built in the 70s. It was good on bungee or the slope, but if you pulled too sharp an angle on the bungee at high speed, it would stall vioelently, with sharp wing drop and corkscrew. I had to rebuild the wing twice because of this and consequent violent contact with the ground at full catapult speed! Flying the HamilcarX will most likely need to be undertaken in scale fashion, allowing time to build up flying speed on the ground, followed by a natural lift off and climb without inducing a sharp angle of attack. Fine pitch props are bound to be helpful with flying speeds not greatly above the stall. In other words, just like the real thing. I don't see any reason why this model shouldn't fly very well. It's a great project. Finally with nostalgia, I have strong memories as a small boy in the early fifties being taken frequently to Whitton Barracks in Birmingham by my dad when he was in the Parachute Regiment and playing in the Airspeed Horsa that was parked in the parade ground there. Sadly a few years later they burned it. Very sad.

Sounds good Simon. Are you working off the 1/72 scale drawing in Aircraft of the Fighting Powers Volume 7, which I have and is very detailed? Looking at the wing taper I can see your thinking, although it will give you a cg at slightly less than 20% of mean chord and that might be a bit marginal in the other direction. It will probably be easy to move the battery back a little bit if you need to though, I'm sure. It looks as if to get the cg to 25% of mean chord you would need to be around 31% at the root, so you aren't going to be far off. Might be a good idea to find some long grass to chuck it into for starters. After that it would make a very interesting slope soarer! You could also consider a bungee assisted launch with power on and that would be getting close to the ideas behind the original!

Referring to Erfolg's last contribution, he's probably right and Simon seems to have drawn the same conclusion. The Hamilcar wing has a fairly sharp taper and it it's a bit sluggish getting up to speed, there might be a tip stalling tendency, particularly if there's no wash-out. I just know that Simon is going to,sort this out. Perhaps a bungee launch might be a good starter! (A very gentle one, of course).

A few tears ago I combined pleasures by riding from home in Sutton Coldfield on my Honda VFR800 to East Kirkby to do my spell as aircrew on the morning shift, bought for me as a birthday present! When I arrived I joined my fellow crew members in the NAAFI hut for briefing by our captain for the day, "Jacko" Jackson. He was a tall distinguished gentleman, who had joined the RAF as a Halton apprentice in 1938 at the age of 15. When he became 18 he trained as a pilot and was flying Spitfire Mk.5s in action in 1941. He flew Spitfire MksVIII, IX and XIV in the UK, Africa and Italy then stayed in the RAF after rhe war to fly jets. Instead of retiring when he would normally have done so, he was asked to take over command of the Battle of Britain Memorial Flight, which he did. When he finally did retire, he maintained his contacts at Coningsby and helped out with the operation of "Just Jane" at East Kirkby. We found out that there is close liaison between The Battle of Britain Memorial Flight and the Panton brothers team and while we were there, Paul Day, in his last year as CO of the BoBMF flew in to East Kirkby in a Spitfire and came to say hello to us! Shortly afterwards I was in the bomb aimer position of "Just Jane" as the four Merlins were started, run up and we taxied out. The engines were completely smooth, there was none of the shaking and vibration that I had expected. As I looked up I could see Jacko's feet somewhere to the side of my left ear and I marvelled at this superman who had joined the RAF nearly 70 years ago and was still doing this. I have to say that I felt very humble. I hope he's still around. So I'm over rhe moon to hear that "Just Jane" is going to fly again, just imagine seeing it in formation with PA474! May I register my huge respect for the two Panton brothers, who are doing such wonderful things in memory of their long lost elder brother who was killed at the age of 19, I believe operating as a rear gunner on a long range raid on Turin in a Halifax. I'm sure that he'd be enormously proud.

Keep going Simon!

I like Steve Hargreaves' kindly observation about filler, with my building competence it's an essential! Lightness is an absolute necessity!

Martin. I think it's water based, it's not cellulose or resin. In texture it's just like an extremely light Polyfilla and dead easy to use. When set it's probably lighter than balsa. "Don't apply at temperatures below 10C, - - - - store above freezing, - - - -can be painted within 10 minutes with water based paints". I find that the best thing is to use sanding sealer when it is dry to seal the very porous surface if painting with cellulose paints, although if you are doping and tissue covering you can go straight ahead. It's the most suitable filler that I've found for use with balsa wood.

Erfolg. The Hamilcar X could not maintain height at the fully loaded weight of 47,500 lbs, the intention was that in this condition the motors would be used under tow for take-off and to greatly extend the glide after cast-off. However it took off and flew independently at a maximum weight of 32,500lbs, which is going some with a total bhp of only 1,930. Maximum speed 145mph, operating speed 120, service ceiling 13,000ft, climb rate 395 ft/minute and normal independent range 705 miles. The wing section is almost fully symmetrical but with a thickness/ chord ratio around 18% is heavily cambered, as you suggest. I don't see anything in the design that should make Simon's problems impossible to resolve, a little perseverance ought to do it. Perhaps the tailplane is positioned a bit low and it's effectiveness reduced by blanketing effect from the thick wing? In this case, enlarging it will probably help, a bit more power never hurts and the cg probably needs to be set reasonably forward.

I'm sure Pete's right. Looking at three views it's probably more the tailplane than the fin that's the culprit though. I've been playing with a profile Vickers Wellesley with first a Kalper 0.32 and now a Cox PeeWee(!) and Spektrum radio and had similar issues. The short moment arm is predictably the problem here though. It's only 30" span, so it's a bit silly but it's a challenge also!

I can recommend Red Devil "OneTime" which I buy from Mike's Models in Birmingham. It's extremely light and sands easily.

Hope you don't mind me commenting on this interesting thread! Erfolg's comments about cross section area are fair enough, but it's also worth noting that this behemoth took off from the ground on the power of two Bristol Mercurys, so I'm not sure that it was lacking in a reasonable lift over drag ratio at the low speeds it took off and flew at. Relative cross sectional area of the fuselage doesn't seem to be proportionately negative in effect, what about a P47, although I appreciate that the efficient ducting system for the turbo-charger probably had some mitigating effect! Also the Avro York was faster than the Lancaster, in spite of a bulkier fuselage. It is true though full size aircraft frequently flew well enough with tail surface areas which seem inadequate from a model point of view (Fw190)? Erfolg's observation about relative side areas forward of the wing and tail areas are probably on the mark. In my achool days I used to make chuck gliders of WW2 fighters. Spitfires and Hurricanes always seemed to fly fine with scale fin and tailplane, as long as I put in enough dihedral. However, Typhoons and Tempests had no lateral stability and didn't work at all unless the fin area was increased. This was obviously down to the side area of the nose radiator, although it seems to be ok with larger models and clearly wasn't an issue with the full size. I think the Hamilcar model project is fascinating, congratulations Simon!

Martin, don't worry, I won't. I'm fascinated by your enterprise though and I reckon it'll be a goer. If it looks right it is right, and it does.

Congratulations to all of the early starters! Plenty of time in hand to fly 'em prang 'em and build a replacement! As soon as I get the Edge 540 undercarriage replacement off the board, I'll get started. I'm still very torn by Martin's built up wing and retract version though, must control myself.

That looks brilliant Martin.

Right! I've got everything. Plan, wood pack, canopies (2)!, pilots, seats etc. Been watching avidly everyone's contribuitions, toyed with the idea of a built up wing with retracts (tempting) but have decided to stick with the pure original Nigel Hawes concept, although might include the plywood inserts to allow the fitting of a fixed u/c, depending on where I will be flying it. Ordered on-line on Boxing day from Giant Shark an XYH35-42 1250kv 45A motor, Hobbyking Pentium 60A ESC plus various bits and pieces, all arrived this morning! Very good. I have got 3S 25C Lipos in 2200 and 3000 capacities to play with, just need to decide on the colour scheme (dither, chew fingernails, tough decision)! So,clear the work bench, roll up sleeves and get stuck in. It's just like the Fizza all over again. one thought, on that I used Carbon Fibre tubes for the wing leading edges, it was very successful and I will do it again here.