Chris Walby
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Tony Nijhuis 72” Mosquito – Build Log
Chris Walby replied to Geoff Gardiner's topic in Tony Nijhuis plan builders
Guy's The results are in....or not! BH and Seagull manuals don't mention flap setting So I measured my PZ mossie (that does give 1/2 and full at 15 & 30mm) and that comes up with 21 and 45 degrees (must be carrier landing setting!) I also measured my BH mossie and that comes out 15 and 25 degrees (where 15 is quite aggressive and 25 seems like air brake territory. Worth watching Eric "winkle" Brown's comments on carrier landings **LINK** as I don't think we really want to get into 4 blades and "hanging it on the props". Just amazing what he did with a 21,000lbs aircraft. I'll measure the Seagull mossie and see what looks right + I might know man that will know the full size settings (just for interest!). -
Ken, I think people have missed my point...its not fast. sort of close to an EFX racer and absolutely nothing even close to Dick's glider (although running it for 4 minutes might be a push!... how long was the "switch incident?". Its not that fast because it an aerodynamic brick! I could go 4S and push the motor even harder but the additional weight will kill it in the turns (assuming the wings don't come off first!). I was merely suggesting to David that making it heavier may not achieve the overall performance he requires from a multi discipline competition. Thinking about it Dick would be in an ideal position to comment (far better than me) as he completes in multi discipline competitions. I would think the best preforming models are those that have their power to weight drag fully optimised, but I could be wrong
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Tony Nijhuis 72” Mosquito – Build Log
Chris Walby replied to Geoff Gardiner's topic in Tony Nijhuis plan builders
Allan, Apologies for teaching you to such eggs, but If its anything like my BH Mossie (and Mike mentions it specifically) with flaps half way it becomes very draggy. Full flap and it has to be flown in over 1/4 throttle or it will tip stall. Better a fast landing or very low pass than tip stalling with full flap at 15 ft (been there had that ). Let me know if you want the BH & Seagull flap settings. -
Decals ordered from Callie Graphics 09Aug18 arrived today including me checking to see where the order was last week and Callie humouring me by confirming dispatch and saying is normally 2 weeks for post! Good customer care and good product.
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Hi How about coming at this from a different direction. I have a fun fighter for one reason...to fly fast (as its cheap, easy to repair and easy to see) Now bear with me and I'll get to the point eventually. I am pushing in excess of 830w/lb so it does fly quite quick, but nothing like an EFX racer, why? Its down to drag and weight and my point is sticking larger an large batteries in will cost you dear (2 x 3S220 might work). American muscle cars vs Colin Chapman (light and nimble) approach. Less weight is less stress for a given airframe for the same performance. Perhaps the other competitors are using lass draggy designs, perhaps a thinner wing section here and more aerodynamic fuselage there and lighter overall. PS - IMHO don't bother with calculations (yes physically test the setup for max power so nothing fails), but unless you are holding it at 100% throttle all of the time it will always be inaccurate, it would be more beneficial to fly the routines and time/measure what you have left. You could go ultra tech and have all singing and dancing telemetry like the F1 teams plus a few people in the back room adjusting setting to scrap that last per cent out...or perhaps its easier to have a glass of wine and watch/learn from the really quick boys and girls. PPS we could head off at a tangent and discuss why a static test differs from a dynamic one.. perhaps for another thread?
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Bert, Laser web site says, Recommended props 17×8-10 18×8-10 19×6-8 20×6" 20x6 to 20x10 would make for a speedy pup and not a lot of low speed fidelity ! However if you consider its not enough engine for the model PM me
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Thanks chaps, I think that answer's Ronos's question. As per drawing or manual With tanks empty and gear up unless they have adverse affects Check C of G anyway around you want, but best not to put your fingers through the wing skin Better to start forward and work back rather than rearward C of G and need a bin liner If it lasts beyond the maiden then adjust to suit your own preferences IMHO you only get a very short period of time to find out how the rates, C of G and flying characteristics all work together or against you.
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PS How come "Vanessa" is used with the model the right way up PPS won't two tanks full of fuel move the C of G further forwards (as they as well forward of the C of G point) and then gear down moves it forwards. Too many permutations.....off to the shed to wire the wing up!
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If its high wing mark C of G on upper wing surface and turn upside down then measure Mid wing mark C of G on upper wing surface and turn upside down then measure Low wing mark C of G on underside and measure right way up Why and what's the benefit doing it this way as opposed to marking and measuring just the underside? Answers please
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Ronos, Looks like your engines might be a tad heavier than mine Have you tried your c of G yet? I had mine up on the stand with the C of G as below Then thought to myself how about some brass nuts! Result should be something like this Rotating mass has increased by 25% and its added another 135g overall to the weight of the model. I'll stick with this until I have everything in and finished and then see what to do with the tail wheel assembly. PS Not machined brass in 25 years...forgotten how much noise it makes
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Hi, I had a think about this as I got into a bit of a quandary having cut the Dual Ace one and then wondered what the offset was , but all was not lost as I had the other one to compare (and lots of checking!). A helpful club member (thanks Martin) suggested I leave the sides so I could brace in front of the bulkhead, the reality is only a couple of small braces, but the advantage is it leaves the datum of the original bulkhead position. Hence once I came to set the drive washer position I just measure back to the sides (they are different lengths due to the off set) and hey presto all done. I am having some challenges with the cowls, but that is more to do with the poor overall fit. Bonus note, machined the spacers of the spinners and tapped the ali spinner adaptor nut. I'll see how C of G goes as I have a nice lump of brass hexagon at close to 150g that I could make a couple out of.
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Power Safe for any receiver
Chris Walby replied to Chris Bott - Moderator's topic in Gadgets and Electronics
Good idea and practical when can we order some! Suggestions IMHO! XT30 connectors are available, smaller, lighter and a bit different from the bigger one commonly used (less confusion in the fuz!) Dual supply, yes to some diodes Dual supply two LED's saying both supplies are live Only a thought as I am in the middle of making a loom and considered this. Dual supply split rail so RX,Thro,Aile,Elev and Rudd on one supply, all other channels on the other supply that way if the gear servo stalls it won't brown out the RX. Could get clever and have dual supply with split bus (and diode facing RX side) that way if the gear servo stall its only going to drag that side down, but if the RX battery fails it would all keep going. PM me and I can send a diagram if I am not clear -
Ronos, I would have considered lead if the AUW was on target, but as its heavy it is better to see what else I can do. I am a bit disappointed as the Dual Ace came out slightly nose heavy and all I had to do was move the RX batteries back to get C of G , bonus it came out very slightly light The problem is that very little weight that far back means I would need a big lump up front, not tried it but it could be as bad as another +300 g just to get the C of G in the right place or make a wire tail wheel. I would be less inclined if it was a retracting original as it would look nice, but at worst a wire version painted black will be less visible (at least its not as much grief as the Black Horse version!). I shall make a wire one up and see what it weighs + the change in C of G. Anyway less waffle from me and more on progress. Wiring loom time as it looks like the RX and everything else will be well forward I am using the front set of wing/fuselage holes. So Red is positive white 1 throttle white 2 ailerons white 3 flaps white 4 gear (different channels from the RX depending on the port or starboard wing) white 5 wing light black is negative And the port plug is a female and the starboard a male type so no chance of getting them wrong Just need to test everything out and the finish off the heat shrink sleeve and cable wrap. Might get on the lathe tomorrow
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Ronos, You are correct, however other owners have experience very "lively if not positively extremely difficult to control" flights at 150mm and the considered opinion suggests 130mm. There is an old saying, C of G forward flies poorly, C of G rearward only flies once. I can vouch that rearward C of G on other aircraft I have flow can be very demanding! There is a downside to forward C of G and that is the landing speed is higher, but the mossie has flaps and if the maiden goes well enough for a landing then its better than loosing it at height ! Hope that helps and if you have any other questions then post a way as the other guys have more experience than me
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Nice one Dave and glad to hear you have (hopefully) sorted an inherent issue with this model. I have to admit that I done nothing yet as I don't like the idea of all the aggravation of another servo and the consequential grief to get the C of G back to where it should be. If you have any photos of your mod it would be appreciated. PS what set up are you running?
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Mixed news tonight on the build progress as I managed to get it together although there is more ply to add. AUW comes in at 6.9Kg so 500g heavier than the recommended range of 6.2 to 6.4 and worst to come that's C of G at 150mm back. I still have some spinner nuts to make (out of steel) and mod the internal nose to get the RX battery in. Once I have the engines in and everything else finished then I'll thing about loosing that 52g tail wheel to get the C of G forwards to the 130mm spot If any others could post their AUW it would be appreciated, that way I might fell better?
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Ronos, I'll PM you. Progress... I went for Jon's option as it leaves me with a panel that can be used to infill the sides if I need to. Ooorrr that's a nice fit The cowl is still ridged which brings me on to my next problem! Problem, with the cowl sitting against the LE of the wing the TE of the cowl sites up (gap) and if I push it against the wing the U/C hole closes and it seem rather stressed. What options do I have? Cut the cowl (slot) at front of U/C opening to allow it to close up Infill the gap (about 10mm at the TE) with a strip of balsa I am tending towards the infill and it leave the cowl intact and less stressed Edited By Chris Walby on 12/08/2018 16:34:37
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