Jeffrey Cottrell 2

Hi Guys Interesting thoughts. Nigel Rule of thumb for me is that a smaller diameter prop turning high rpm, will fly the model faster than a larger prop of the same pitch but turning slower. However the larger prop will produce more thrust, so improving vertical performance. Given the current F3A trend is towards slower, but constant speed flight, seems to me that slower but higher thrust is the area I want to be in. Anyway, all conjecture at the moment. Final proof will be how (if) it flies. Can't say for sure if the build is straight and true. Not up to me, but hoping so. New set of wings is still an option, if the current plan fails. Worth going with what I have, see what happens. Rough and ready calculation says I have lost 7% of the wing area. Don't think that will make too much difference. Could start out with a new set of wings, but that would be admitting defeat before battle had even been joined, plus wasting all the effort to make the current wings safe to fly. KC Sorry I thought I had mentioned my proposed power train. Anyway: Motor HK SK3 - 5045 - 450Kv Lipo 4000Ma 6s Esc Plush 32 80a Has 5a bec, but might use separate ubec. Prop 14 x 6-8 btw, I did throw away the wing root section. However Geoff at Foam-Wings does have Saphir wings to hand, which I believe are the same. Can't imagine any washout on an F3A wing, which is designed to operate upright or inverted. Please everyone keep your thoughts coming. Finding them very useful. Jeff

Hi Nigel and welcome Did wonder a couple of times whether I had bitten off more than I could chew. Couple of thoughts kept me going. First of all, do you recall someone started a thread about lockdown projects, all those repair jobs at the back of the garage? Looking at some of those, which were literally basket cases, being restored to fly again, what have I got to lose? Second, there's something satisfying about making a silk purse out of a sow's ear. Of course it may not turn out to be a silk purse, more like another part of a sow's anatomy but here's hoping. Finally the mercenary aspect. The Smart Move actually cost more than the Excelsior. Although neither was very expensive not going to give up without a damn good try. Thanks also for the prop details. My electric set up will be turning a big prop relatively slowly, so comparisons with a 2-stroke are not really valid. However some of the 4-stroke figures make interesting reading. My prop calculator, again theoretical, says turning a 14 x 8 prop at 7900 rpm gives average 893w and max 968w. Looking at the figures for the OS 81 and 91, I'm losing a bit on rpm, but with a higher pitch prop. Either way the model is listed for 60 4-strokes, so if I can even approach the performance of an 81 or 91, should be good enough for me. As always the proof of the pudding is in the flying, but everything I've learned so far is encouraging. Work in progress Jeff

Hi Guys Been looking at prop sizes for the Smart Move. KC kindly posted the instructions which recommend 40 2-stroke or 60 4-stroke. Obviously the 2-stroke would use a relatively small, high revving prop, but the recommendation for the 60 4-stroke is 12 x 6 to 13 x 6. Anybody running those sizes on a 60 4-stroke, could give me the rpm achieved? My electric set up suggests 7900 rpm on a 14 x 8 prop. Feeling is this will be plenty, but would like to have a closer idea. Thanks Jeff

Hi Bruce That link should take you to a page that does say 'under new management' but it should also include a mobile number for Geoff Hodgson. If it doesn't, here you go 07966 084294. I have contacted him a few times now on this number. Haven't taken the legs off mine yet. I did find some wheels with a thin enough hub to use the existing axles. Trouble is they are plastic wheels and I would question their strength on a 9 1/2 lb model. Can't really beef up the legs, but if the wheels do fail, I can get new legs modified with a longer axle, so I can use some alloy hub ones Bondaero sells. That's the plan anyway. I've been crimping my own leads for quite a while now, and generally produce a satisfactory job. My question would be that I understand servo plugs are only good up to about 3a. Won't get anywhere near that on one servo, but running 4 x digitals and 1 x analogue the lead from the battery to the receiver is suspect. I got round that by fitting two leads from the switch to the receiver. Ideally I should have plugged them into sockets at opposite ends of the receiver but didn't have enough spare sockets, so they had to go in side by side. Near enough. Sadly, no maiden yet. Waiting for wind and rain to die down, but also trying to persuade a clubmate to join me. Need to do a 'motor running' range check, which is only safely done with two people. Don't worry, it's not going anywhere. If you're intermittently surfing, does that mean you're in Cornwall? ?? Jeff P.S. pm sent

Hi KC Yes, that will be a consideration. The fuz already has a ply box mounted on the firewall, some 40mm deep. The motor I am using has both bolt on and collet type prop drivers. Using the collett type, that puts the prop driver some 75mm from the motor base. Add that to the ply box and that means the driver is some 115mm (4 1/2") from the firewall. The motor is also relatively heavy, so I'm hoping that will be close enough. We'll see. Out of interest, if you look at the picture of the fuz before I modified it, that large ply plate with the wing bolt fixings in it was also the battery mounting plate, at the REAR of the wing opening. What that did to the balance I do not know. Oddly enough, that plate had written on it '4-Max 4s 3700'. Mentioned it to George and he remembered the customer insisting he was going to use 4s, despite George's advice to go 6s. My set up is based on a 4000 Ma LiPo and, in theory, should give me about 11 mins of mixed flying. Haven't yet decided that for sure, but if a 4000 will fit, that would be the minimum size I would use. After all, if I need extra weight up the front, might as well make it do some work. I suppose, if the worst comes to the worst, I could re-make the motor box bigger, and cut a hole in the firewall to allow the battery to slide forward as far as possible. I'm also converting to closed loop for the rudder and a single snake for the elevator, which should minimise weight at the tail. For the moment, concentrating on getting the wing done. Once I finalise its mounting, might be able to mount the servos further forward as well. Every little helps. Clearing out the junk from the fuz has lost a lot of the epoxy as well. Maybe not as light as it would be if I started from scratch, but shouldn't be too bad. Work in progress Jeff

Hi KC Thanks for doing that so quick, much appreciated. That's certainly the model I have. All my measurements are pretty close to yours. Only discrepancy is the instructions show the fuz length at 148cmm, which is 58" or so. However, this might have been measured including the rudder, or possibly from the prop driver. Either way, no biggy. The extract from the instructions will be useful too, when I come to set it up. Already produced a couple of encouraging results. First of all, the root chord on mine is now 335mm. Allowing for the chunk of the centre section I cut away, it probably started at 355mm. Th c/g is shown as 195mm from F2, which comes out well over half chord. This is a question that came up with the Excelsior as well, c/g being further back that expected. Turns out on checking that that's right and due to the sharp sweep back on the le. All confirmation I'm on the right track. Most surprising of all is the dihedral. When I cut the panels away I didn't measure to any accuracy. Figured I could sand the roots true afterwards. Your instructions show 36mm under each tip. With one panel flat, that would mean the other tip propped up 72mm. Without any information to go by, with mine on the bench I have to prop up one tip by 60mm to get the centre join ok. So, 60mm as opposed to 72mm. Good enough for me, by pure luck. Not sure what size prop a 60 2-strike or a 90 4-stroke would turn. Mine's going to be electric, and the figures for my set up are 7900 rpm on a 14 x 8 prop. Anyone suggest how this might compare with the ic engines above? So far, looking good. Work in progress Jeff

Hi KC, thanks Been researching what there is on the net about DSM. Never seen mention of two sizes of Smart Move. No rush, but when you have a minute could you measure the span of the one in your garage? Might answer the question. Cheers Jeff

Hi Guys Sorry forgot to add a couple of pictures. This is a quick look at the model with the shortened wings. Doesn't look too out of proportion, does it. This is a shot next to Excelsior for size comparison Jeff

Hi Guys With the Excelsior pretty much done except for the noisy bit, could I express my thanks to all who contributed, with special mention for Peter Jenkins and Nigel R. Unused to having a clear bench I have decided to wake the Smart Move from its hibernation and do some more on that. Don't want to clutter up this thread, so I have started a new one, here. All welcome. Jeff

Hi Guys With the successful conclusion of the Excelsior re-furb, turning my hand to the Smart Move. This is going to be more than a re-furb, read total rebuild. So, bit of background. I bought the Smart Move and the Excelsior both at the Wings & Wheels show a few weeks ago. The Smart Move was on the B&B stand and looked fine from the outside. However the wing was held on with masking tape, and I couldn't get a look inside. The stallholder said the seller had 'forgotten' the wing bolts, and my spidey sense was absent that day, so I bought it. Ok, price was reasonable but still....... When I got it home and pulled the wing off, a horror story was revealed. The fuz was literally held together with great gobs of epoxy, and the radio install was not the best (that's being kind). However the wing was even worse. The retract servo was in a hole that looked like it had been cut with a chainsaw, and the retracts and wing servos had been GLUED in. I though about it for a while, even posted a question on GBRCAA, and the general conclusion was that the wing was not safe to fly without modifications. In the end I went drastic, and cut the wings in half just outboard of the fuz joint. Lined the roots with some 1/8 balsa to form the root joint. Now, according to my info, the original Smart Move was 60" span. Mine when I got it was 55" and after my mods it was down to 52". Definitely not right somewhere. However a trial assembly looked in proportion, so not too bad there. I had to cut the retracts to get them out, so threw them away. Removing the wing servos took quite a bit of the foam core with it, so I used SLEC side mount brackets, mostly to hide the damage. Currently in the process of filling in all the holes in the wing, and after that will re-join them with proper glass re-inforcement at the centre. So, first question. When I cut the wing panels I managed to get them quite accurate (luck) but temporary join showed a small amount of dihedral. Propping the wings up at the join angle, a ruler across the wingtips showed a gap of about 3/4" at the centre. Not much but will it effect the flying? Inclined to think it won't but your thoughts? Should be some pictures around here, to show what I am facing. Any suggestions, ideas would be most welcome. Jeff Wing centre as received And now One wing holes filled in other to be done Fuz as received And now Control snake layout, fuz Control layout, tail

Hi Peter The scenario you describe could possibly happen but it would require a lot of other things to go wrong as well. First of all, obviously plug the starter into the wrong sockets. Mine are always colour coded Red and Black, so a sudden attack of colour blindness. Second, as Peter Jenkins points out, starting with the throttle too high. Finally to have a motor that will actually run at high speed in reverse. Some don't. There is an old saying: However foolproof you make something, nature will find a better fool. Me, I'll keep with the set up I have. Jeff

Hi Peter Thanks for that, good to know. Now, I can't fit the model in my car in one piece, so I have to unplug the wings to get it home. Would I be correct that unplugging the servo lead would be the same as having a switch in the circuit? Also since the retract lead would have both positive and negative going into it, if I made up an extension lead with only red and black leads, could I use that for charging? That's two possible sources of unreliability done away with. Your thoughts? Jeff

Martin Me too, been there, done that. You could order the buck module at the same time, but they're both free ship so it doesn't really matter. Jeff

Hi Peter Me too, mine are pretty good. Wonder if you can get the holders with safety clip as separate items? Best of both worlds. Might try one of those Maxlock ones in 9 way type, but only if I can get round George wanting £4.75 shipping. Need three way for both ailerons and retracts. Brings me neatly round to the next question. Currently running the retracts from the main power pack. Probably won't be using them for the first few flights, but when I do, like the idea of running from a separate pack. So, how to wire it? My guess would be that the negatives (Black) from the main and the retract pack are joined at the receiver. Then the signal wire (White) comes from the receiver, and the power (Red) wire from the retract pack. How does that sound, any better ideas? Jeff

Martin CZ is Czechoslovakia. Switch to shipping from China (CN) and you should be fine. Jeff

Hi Peter, just a thought. Ian at Modelfixings is now stocking quite a range of RC accessories. Among these are some servo extension leads which incorporate a locking clip against vibration. Have a look here. Might be worth a try if you can't get Maxlock for any reason Jeff

Hi Bruce, couple of thoughts Is the Rocket you mention the Terry Anderson design from a while ago? Sometimes I buy plans just for curiosity, and that plan was one of them. Dug it out for another look. Very Aerostar'ish which is no bad thing. Looks to me it could be built very light,so ideal for electric. Might put it on the build list for a possible gap in the schedule. I assume Bill Manly is 'Billkits' yes? If so, what's the quality like? Talking to Geoff at Foam-Wings, I get the impression he has a computer controlled wing cutting machine, which should ensure accuracy of section if nothing else. The powerplant you have to decide on, is this for a Rocket or a big Excelsior? Reason I ask is while I was contemplating the Excelsior, I put some figures into e-Calc and came up with an electric set up which looks pretty close to the Thunder Tiger I now have on mine. Thing is, on current prices I reckon about £160 for motor, esc and batteries. Sounds a bit better than £600. Details available if you fancy a look. Meanwhile agree with you about servo plugs. mentioned this a few times on the forum, but all I seem to get is that they will be fine. For me, Murphy's law will surely say different. Couldn't do much about the basic layout, but I did run two separate leads from the switch to the receiver, just as insurance. Time will tell. Finally, swapping your M140i for an M2, sounds good. Can I assume you couldn't afford a Mk 2 Escort? ?? Jeff

Hi Guys Martin Quite why it's called a 'buck' module I'm not sure but it's the one t'other Martin linked to a while back, and also in his last post. Cassandra Of course, this one's simpler still One thing. The buck module does have an led to show it's working. If it was covered in clear rather than black, you could see this through the covering Just a thought Jeff

Gary LiPo is easily removable so I can balance charge. Factory referred to is J. C. Model supplies, i.e me. Jeff

Hi Peter I think Bruce was referring to my questioning top of the range motors, with distinctly low end servos. I note his comparison of the Mk2 Escort with his BMW. Think fairer to say if you took a Mk2 Escort, with its 70's suspension and brakes, and put a BMW motor in it. Wonder how long it would be before you saw the wrong side of a hedge. Jeff

Hi Gary Sorry, clean miss on this one. In the post it says driven by an INTERNAL LiPo, which means they're both outputs. Also veiled suggestion that this came from China. Not so, I built it with my own two hands. Oops Jeff P.S Well done Cassandra, got in just before me J

Hi Guys Seems this thread has drifted a bit from my original question. Just to prove I'm not immune, here's the latest product from the factory. Suppose you could call this a Power Pod. 12v drive for pump and starter, plus a 1.2v glow drive through an XL4015 module. All driven by an internal 3s LiPo. Hindsight says two things. Using a 3000 Ma LiPo so how long will that last running the starter. Flies a model for some minutes at a higher current, so should be ok. Time will tell. Also perhaps should have used different plugs for each purpose. Just have to be careful not to plug the glow lead into the 12v output. Have you seen the price of plugs nowadays? Anyway here you go Jeff

Hi Bruce, thanks That's got to be the clincher, hasn't it? Must admit I was puzzled when I did the first check. Still of the opinion that the model has flown but couldn't be very well with the c/g so far back from where I would expect it. Having talked to Geoff and got his figures for the Saphir, and also putting the dimensions into that site which calculates c/g, turns out it's pretty much where it should be. The info from Garth makes three sources that say the c/g is correct. Can't argue with that. Did ask that Geoff keep me in the loop about DSM kits, but I wouldn't hold your breath. When I spoke to him last week he said he was waiting for some extra long balsa sheets. Trouble is, when I first spoke to him, couple of months ago, he was waiting then too. Ho hum. If he ever does produce these kits, I would be in the market too. I know I have the Smart Move lurking at the back of the bench somewhere, but there is still so much work to do, might give that best and start new. So, on to your Excelsior. My thinking always is, if something is not to your liking, replace it. On that basis, you've obviously seen something about the current closed loop that's giving you doubts. My advice, replace it. Bit too late if you find out it's not up to scratch on the first flight. I replaced the wires on mine because the builder had used some plain, not covered, stranded wire. Over use that will saw its way through the fittings, so it had to go. By the same token I also replaced the elevator pushrod. Old one might have been quite serviceable, but it was made from a very soft and rough piece of 13mm square balsa, with great gobs of epoxy on each end. Now a piece of 13mm dowel with the wires epoxied into proper slots, and bound with kevlar thread. Whatever else fails, it won't be that. Another question. Your Excelsior has a YS 120 on the front, mine has a Thunder Tigre Pro 120. Neither of these is a budget piece of kit, so why did both builders choose cheap and cheerful 3003 servos? Probably just about ok for torque, but not much to spare, and being analogue wouldn't centre too well either. Why spend so much on a power plant, then go budget on servos? Beats me. Just my thoughts Jeff

Hi Peter Thinking along the same lines myself. Set the control movements to those recommended in your book. 15 deg on aileron and elevator and 30 deg on rudder. In the flesh, these movements look high to me, so I will set rates at 70% or so for the first flight. Take your point about never having an issue with your F3A models, but how many have you flown now, in total, and how many of those were bought second hand from an unknown builder? You'll have to excuse me having a few qualms. Jeff