Craig Spence

Hi all, I will be building a 1/4 scale Jerry Bates Bell P39Q Airacobra very soon. It will be electric powered with x4 6 cell batteries up front. I have started a blog on Facebook as well if anyone wants to keep up on there https://www.facebook.com/Craigs-Bell-P39-Airacobra-build-102061535705394/ At the moment I’m just doing small bits whilst waiting for the laser cut kit to arrive. I’ve started the 50cal guns, center line tank and also general hatch vinyl. Ive also added some of the schemes I’m thinking about for finishing.

Thanks gents, I've already ordered a new one. Repressing new bearings in crankcase would be a bit out of my skill & toolset. I think now I could of perhaps overloaded them?, although not out of the reccomebdations!!. They are old but barely flown, we'll run. They have always used xoar 11x6 after break in period. I then upped them to APC 11x7 for a little more thrust, well perhaps with the extra pitch & weight was enough to push it over the edge. I'm just praying that the other one isn't suffering?, seems fine but then the other one did as well?. Once the new one comes I'll put a good few tanks through it then try to tune them so there near the same again!, & then start flying again. Cheers for the help fellas.

Nothing seized Dave, it just sheared, striped the lot & all smooth running no indication of faults just a material failure I think. Gutted!, lol.

Thanks lads, I have stripped it completely & no obvious signs of failure apart from as said by Dave, it's sheared on the power stroke & continued down. However I can't explain the damage on the lower end of the piston head?, perhaps myself trying a restart!?. Oh well, I think it goes to show that electric starters may be the cause!, I bet if I used the chicken stick all the time like I used to I wouldent have had this happen. Fuel locks etc.. Something to bear in mind I think. I personally do not think that is normal wear & tear!. The search begins, Thanks for the help.

Gents, I have discovered the problems!, I have to say I am not happy but delighted at the same time (explanation after). So, the valves and springs are fine, crank pin has sheared and piston rod has punched its way through the crank case!!, the piston head is stuck and it has damage to the lower half. I have attached some photos, someone please explain to me how this has happened because for the life of me I have no idea!!!, the highly annoying thing is that this engines was from a twin!, so I can't really get a new one!!, ill need a secondhand one thats run in quite a bit!!. Or Ill have to spend ages bedding it in. The massive plus side is, if that had gone in the air, likelihood is I would have probably lost the plane. Nice hole! Sheared pin! Stuck piston head! Help and explanations very welcome, Cheers, Craig.

Thanks gents, I'll look in crankcase first & cross my fingers!, then the rocker cover, I'm hoping this doesn't turn out to be a big job. It's definatley not a copy, I find it strange though as although old they haven't done a great deal of work. I'll keep you posted. Cheers.

Hi all, I run both my SC52fs today in my Mossie, had a tank through both on the ground & then in the air. When I restarted them for another flight I heard a loud crack & the STB engine stopped running?, on inspection I found that I turned with next to no resistance!. I thought the prop nut had come loose but all good there, so what is it? = broken rod?, crank?. I will be taking it apart later but I'm really looking for ideas & why it happened. The engine was running fine then crack!. Feedback greatly appreciated & I'll keep you updated when I strip it. Cheers, Craig.

Matt did indeed do a good job there, I also love the sliding canopy!. Plenty of ideas now, just a bit (hours upon hours) of research now. Cheers fellas.

I'll have a look again tomorrow Paul as I'm turning in soon, but it's on u tube I think under P47 D working cowl flaps, something like that anyway. It's time consuming & requires a lot of patience but not that difficult & looks great in my opinion. Cheers.

Cheers for the feedback gents, I saw the same video with the wire, also with wire & tiny push rods. Both worked very well. I didn't know the big foamie done that, one of the lads at the field have that model so he'll have to demonstrate & I'll have a look at components. Simon, I know the flaps are for cooling but what I am trying to imitate is start up (oil on start up like you see on the films) also I read that they most commonly used them on high power/ low speed?, not quite sure what that means but I'm assuming take off/ landing?. Also if they ever had engine problems/ overheating I'm sure they opened the flaps to cool the engine, thinking back on old films im sure black smoke used to plume from the cowl when they had engine bother?. I'm no expert, just researching & looking for help on ideas. Cheers gents, Craig.

Hi all, After researching my next build (Brian Taylor P47 D 76" I come across a few videos of working cowl flaps. Has anyone done this & would it be feasible on a 76" model?, also I had an idea of creating smoke to come through the cowl flaps to imitate soot escaping but again don't know if & how I could do that. Thoughts anyone?, Feedback greatly appreciated. Cheers Craig.

Hi all, Well after a very long break I have came back to the mosquito. I removed the solid elevator & made a built up one, tail cone remade as a two part cone to allow access to elevator & rudder linkages. Rudder, elevator servos moved forward & tail wheel changed to small foam one to help with CofG. Made a dual battery holder in the nose along with pouring nearly a pound & a half of lead in the nose. CofG just about bang on now. I found the issue with the engine that kept cutting out, I had a servo which was moving erratically by itself, this has been changed out now & both engines are achieving about 13min plus before one cuts out. On the low end the engines are out by 10rpm, this will be easily sorted by leaning the rich one. So there are only a few small issues now - 1: I had to change the tail wheel to a castoring tail wheel - big mistake!. The plane literally just goes round in a circle when taxiing, torque & thrust?. So plan is to add a mini servo & a snake back to the tail wheel. 2: Cowl adjustment - add extra fitting points (not happy about this!, something not scale ruining the look). 3: Undercarriage doors on STB nacelle - one door is warped!, a little bit of patient bending, taping & leaving overnight I think. That's it!, I'm awaiting a pilot to maiden it for me. I shall take some photos of mods & vid maiden. After successful maiden (hopefully!!!), I will be doing more weathering, panel lines, wing tip lights, antenna etc, etc... It continues to go on & on lol. Cheers, Craig.

Hi Simon, Thanks for the info, I think I'll keep on looking, it would be great to get a servo in the spec I want for £30 as it would free up some more cash. The ones I'm happy with at present are £40-£50. Do you like the club?, I've been there once for a look around about 4 years ago. It looks a really good patch and well looked after. That's a shame about the dead stick, I just repaired the under carriage on 70 class Sbach, it's hard to reinforce such a light airframe without affecting the weight. I ended up layering 4 bits of 1/8" ply drilling through them and attaching the undercarriage, then slid it in glued!, I think the undercarriage would snap before this now lol. I got mine from carbon copy UK, and many others, there very good. Thanks again.

Hi Rich2, I've found hitec HS5585 mh digi coreless. They seem good for torque at 14kg, cost £40.47. I'll keep looking, but happy with these, as said previously the minimum requirement States 13kg and I intend to stick to it. Thanks very much for the help, gonna look at props again now.

Thanks very much for the replies lads. I'll have a look at different servo's. I just thought as the recommendation is 13kg I should be around that mark. It's all good if it saves a little cash, the props a wise one as well. Cheers again.

Hi Mike, 18x8 prop is the running in prop as well isn't it?, that would be handy. From past experience though the difference with a lower pitch wide prop is great, I'd like to see if I can get anything. I'll have a butchers at that kill switch as. As for noise?, I'm not sure and I'll have to ask, the new club I'm joining is by the M25 and a gun club!, houses arnt that close so I imagine I may be ok. Having said that though, I do like the Pitts mufflers. Do you get much time of your engine battery?, few flights or more?. I'll have a look at Weston as well, thanks very much for the help. Much appreciated from all. Cheers.

Adrian, Thanks for that I'll have a look on just engines, I'll also do a bit more research on the prop front. Cheers.

Thanks Adrian, can you recommend a good kill switch?, I've read up on some mentioned and they say you need to cap them?, as they can cause minor issues?. I have found APC do some larger props with wide sizes 20x6 wide from memory, just wondering if they drill out well?. On my 70 Sbach I run a 15x4 wide prop and it's fantastic. Any experience with these larger props?, I'd prefer a wooden one but don't seem to do wide sizes. Cheers, Craig.

Hi all, Well thanks very much for the warm welcome back and especially all the quality information. After doing some more research I found out that the minimal recommendation for the servos is 180oz/cm which equates to a 13kg torque servo. I decided on this Savox SA-1256TG High Torque core less Digital servo @ £50.99. What torque would I require for the throttle?, shouldn't be much surely?. Decided on x2 3000mah LiFe batteries with a powerbox sensor switch- does the switch just work off of the one battery then switch to the other if a problem occurs?, or runs on both?, in the latter case should I chose two lower mah batteries to combine to higher all up mah??. Also, is LiFe the same as LiFePo?. The ignition battery, would a 1500mah last all day or just a flight?. The hinges are pre installed although not sure if glued, they look pretty good and heavy duty. Good pack that comes with it from the looks of the manual. I'm undecided whether I should upgrade TX to a Spektrum DX7 or DX9. The DX7 looks the part and it seems Spektrum have upgraded all their gear. I'm still research kill switches. Thanks for feedback in advance, Cheers all.

Hi all, I haven't posted on here for some time, I'm coming back into flying after a 3 year break and im shocked at the vast changes if im honest. So to the topic, I will be treating myself in January to a pilot rc Sbach 342 30cc. I have loads of questions and need help if you could. 1; The model weighs 4.85kg (as it comes). It requires x6 servos, what torque should I be looking at on them?, also does the throttle servo need to be of high quality?. 2; I am looking at LiFe battery's for the receiver, what mah will I require 3000+? 3; what battery should I have for the engine?, DLE 30cc. 4; Is a battery backer the way forward or dual batteries with dual harnesses suffice?. 5; Can you get 20x4wide wooden props? and would this be ok for DLE 30cc. Prop range (18x8, 18x10, 19x8 & 20x8. 6; I take that I will need a kill switch?. Any help would be greatly appreciated. Cheers, Craig.