Steve Hargreaves - Moderator Posted June 6, 2011 Share Posted June 6, 2011 I think it would be a bit marginal sceadu498....a 15 is a full 40% smaller than the recommended 25 which is a lot!! Plus this model needs a 3" spinner up front & I would guess the biggest prop you would get on a 15 would be an 8x4.....more likely a 7x6...most of which will be shielded by the spinner!!! How much does the 15 actually weigh....? Ball bearings can add quite a lot of weight so I'd be surprised if it was much lighter than the plain bearing 25.... Quote Link to comment Share on other sites More sharing options...
J V R Posted November 12, 2011 Share Posted November 12, 2011 A couple of pictures of my work done on the M M Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted November 15, 2011 Share Posted November 15, 2011 Looks great JVR....mine is finished & awaiting its maiden flight.... Just a few thoughts from me regarding the build..... 1) Keep it light 2) Use a light engine 3) Keep the front end VERY light 4) Make good use of a sanding block up front to keep the weight off 5) Make sure you build it light...especially at the front From this you might deduce that it can be nose heavy..........you'd be right....!!!! I ended up with my servos near the tail so do be careful & check the likely CoG as soon as you can..... Quote Link to comment Share on other sites More sharing options...
J V R Posted November 15, 2011 Share Posted November 15, 2011 Hi steve, I have just checked the CoG as it stands with out any covering minius the spinner ( just the back plate ) and it looks like I will have a problem, and I still have the engine cowlings to fit. Hopefully there will be enough room to fit the battery behind the servo's up against the rear bulkhead behind the wing............ Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted November 16, 2011 Share Posted November 16, 2011 Hi Jan...replied to your PM.... Don't forget there will be more covering behind the CoG than in front.....plus you need a pilot & the canopy which will help get the weight towards the rear......can you sand the front down a bit more? Sand the balsa inside the cowl to make it thinner/lighter.... What sort of spinner are you using?? I bought a lovely 70mm ally job which looks superb but adds a load of weight right at the front. I had to replace it with an 'orrible white plastic one which is a lot lighter......the ally one is in the drawer.... There is plenty of room to fit the servos in the rear if you need to.....not ideal but needs must when the devil has a grip on your CoG....or something like that anyway... Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted March 26, 2012 Share Posted March 26, 2012 Well my Midget Mustang has finally flown....& what a great little model it is too..... I was a bit worried that my model was a bit heavy but she flew very nicely...... Take offs can be a bit dodgy as you need full up elevator to stop the model nosing over & this can lead to it leaping off the ground at a very unheathly angle if you're not careful..... My first flight was very exciting owing to too much elevator throw......this coupled with the short tail moment made for a very undulating flight path. The ailerons were a bit sluggish too so I have a slow-ish roll rate & very touchy pitch control....the poor pilot must have been very seasick.....&....a first for me....not one single beep of trim was needed....she flew straight as a die. Second flight was much better.....more movement on the ailerons with less Expo & a bit less movement on the elevators with lots more expo......I find she needs a fair bit of elevator at lower speeds to flare for landing. She will turn on a sixpence however....useful in a pylon racer I suppose..... a quick bank & yank & she's off in the other direction before you know it. Being a bit of a hooligan I kept the throttle pretty much wide open for the duration but I can report that she will trundle around quite nicely on about 1/2 to 2/3rd throttle OS25FP on a 9x6) & that the stall is completely benign..... Here she is...... I think the last word must go to a clubmate who joined me in the Pilots Box & said "You're having WAY too much fun with that........!"...... Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted August 2, 2013 Share Posted August 2, 2013 Hi All, I'm in the process of putting one of these together for my Fun flyer, I'm coming along nicely and just got to the stage of mounting the firewall but before i do I have a very nice blue os .25 la with a pitts style muffler. I'm intereted to know if there would be any issues mouning the engine upside down so it's completly enclosed inside the nose cone. I'll admit i have a thing about engines sticking up out the front of planes. dimension look good it will fit inside and the head will poke out just where the small scoop goes on the bottom. can you guys see any problems with doing it like this or will i be better of leaving it as is? Thanks Matthew Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted August 2, 2013 Share Posted August 2, 2013 No reason at all why it shouldn't work OK Matthew.....make sure the tank is at the right height & you'll be fine I'm sure...... One thing though...Pitts style mufflers are usually designed to work with side mounted engines so the exhaust emerges from the bottom.....using one on an inverted engine would mean the exhaust sticks out the side.... Do be careful to keep as much weight as possible OFF the front....I didn't & it was hard to balance...I even ended up with the servos at the tail end....Probably my fault as I'm not known for my light building but I would suggest you hollow out all the block balsa at the front as much as you can.....its a very short tail moment on these models.... Enjoy.... Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted August 2, 2013 Share Posted August 2, 2013 Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted August 2, 2013 Share Posted August 2, 2013 thats really good news. i've read about them being nose heavy so i'm looking at either making a vac form nose or a very light weight sheet nose probably removable. do i need to worry about heat build up or should it be okay if i have all the relevent holes in the nose open i figure it should get enough air. now to try and get the old exhause off someone rounded the screws off Thanks Matthew Quote Link to comment Share on other sites More sharing options...
kc Posted August 2, 2013 Share Posted August 2, 2013 Removing exhaust bolts can be a pain...try heat only on one part....maybe use a heat gun etc, maybe running the engine on bench mount might help.Maybe try a tiny pair of Mole wrench or cut a screwdriver slotGrinding the head of with dremel type tool maybe a last resort but ensure the grinding dust does not go inside the engine!Some of the traders at shows sell 3mm allen head bolts in longer lengths like 25mm if you need new ones.Edited By kc on 02/08/2013 13:13:03 Quote Link to comment Share on other sites More sharing options...
Martyn K Posted August 2, 2013 Share Posted August 2, 2013 I would use heat - then more heat. It all depends where the bolt has siezed. If its in the silencer then taking the bolt heads off wont really help - in fact you will be worse off. However, it is more likely to be in the crankcase threads, in which case pop the engine into the oven (low - about 120C) for an hour - let the heat really get to it and then try again. Try cutting a screwdriver slot in the end of the bolt - take your time - you only get one attempt at this. You can also try immersing the engine in thin oil and leave it for a few days - that may help. I would be nervous about using mole grips though. You will be very likely to shear the head off completely Good luck Martyn Edited By Martyn K on 02/08/2013 13:41:38 Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted August 2, 2013 Share Posted August 2, 2013 hello matthew...try applying heat to the bolts using your soldering iron....may help you get them loose..... ken anderson...ne..1 ...get them loose dept. Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted August 2, 2013 Share Posted August 2, 2013 gonna tackle that challenge tomorrow i think spent the afternoon fixing a st glider for someone and a little mikro kite thing i'll be really chuffed if that exhaust does fit will make the plane look so much nicer. i'm slowly getting to the removable wings or canapoy decision. Thanks Matthew Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted November 12, 2013 Share Posted November 12, 2013 Not posted in a while but slowly adding the final touches to the Midget Mustang, Not much more left before i can test fly it Edited By Matthew Horsell on 12/11/2013 11:06:05 Quote Link to comment Share on other sites More sharing options...
Glenn Stratton Posted November 12, 2013 Share Posted November 12, 2013 Hi Matthew, how did you get on with the seized exhaust bolt issue? Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted November 12, 2013 Share Posted November 12, 2013 I found a decent screw driver that just about got the screws out ,I found once I cracked them they came out easy Quote Link to comment Share on other sites More sharing options...
Glenn Stratton Posted November 12, 2013 Share Posted November 12, 2013 A short sharp tap on the seized bolt head can sometimes work to loosen them, but you do have to be careful that you don't damage anything else in the process! Good luck with the maiden, hope you have a successful flight. Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted November 23, 2013 Share Posted November 23, 2013 Well The midget mustang is all finished charged and ready to fly, might be taking it this afternoon, Only problem is and I don't know if I should be worried or not it's come in at 50oz with no fuel, Balances with no weight on either end ( although I find it so much easier to balance it upside down), My question is should I be looking to reduce the weight a little before I fly it, Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted November 24, 2013 Share Posted November 24, 2013 I've just popped mine on the kitchen scales whilst SWMBO wasn't looking.......53 oz with an empty tank so yours should fly fine Matthew.......the tricky bit is letting the speed build up enough without her nosing over....you need full up as she starts rolling & then slowly ease off the elevator as the speed builds or else she'll stagger into the air with insufficient speed & you risk a stall..... Once in the air she's a pussy cat to fly......Enjoy!!! Edited By Steve Hargreaves - Moderator on 24/11/2013 13:53:23 Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted November 24, 2013 Share Posted November 24, 2013 Well I did the first test run of the engine yesterday runs really well. I was a little worried that the exhaust would be on the loud side but it sounds quiet tame was going to test fly today but other commitments got in the way, hopefully next few days and it will be in the air Quote Link to comment Share on other sites More sharing options...
Matthew Horsell Posted January 22, 2014 Share Posted January 22, 2014 It Flew if I'm honest I was a little nervous and should have had more power on but it flew Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted January 22, 2014 Share Posted January 22, 2014 Well done Andrew, nice colour scheme. Quote Link to comment Share on other sites More sharing options...
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