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Crescent bullet replacement


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Not so much a build blog - more a statement of intent! After crashing my beloved bullet at the tail end of last year I have finally got around to starting to build a new one. I am using the PB Models kit, sourced from Cloud models. Wood is pretty good and the fittings are also pretty good. I won't post each and every step here as this has been done for this model by far better builders than me. I will however detail any changes I make that I think may be of interest.
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Hey Willyuk,

I am intending on using an SC 46 that has been run in but seen very little use. I had an iIvine .39 in my last one and whilst it was fine a little more power wont hurt.

The main changes I intend on making are:

Hitec HS-81 in each wing for the Ailerons

Steerable nose wheel

Cross grain inner and outer tip sections for the elevators and rudder

Thin ply facings for the elevator and rudder where the horns are fitted

I am also considering glassing the fuselage and, possibly, the wings. Partly as I haven't done it before and partly for a neat, hardy finish. I am a little wary of making it too heavy though so will decide when I have to and can check the weight without covering. If it isn't glassed then I will use Oracover and am currently leaning toward black and gold or black and red.

All subject to change of course!

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Good luck Jack, will be following this with interest - love the bullet!
Just one thing about Hitec HS81 - the nylon gears are very fragile & easily strip.
I had a pair installed in Wot4 wings & flight loads stripped the gears.

I'd strongly recommend the HS82MG or HS85MG - virtually the same size & weight
as HS81 but metal geared & much more robust.


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Thanks for the encouragement Richard!

I hear you on the HS81's. I was hoping that they would be OK but suspected it was a bit risky. Of course they have the advantage that I already have them (poached from another project) but I will probably play it safe and order some with metal gears.

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Thanks for the suggestions guys. I have gone with the HS85MG option. I have used these before for wing servos' and have confidence in them. They are also only require small holes in the wing They should arrive today so I hope to start on installation tonight.

I have the fuse in my SLEC building jig now with f2 and f3 fitted plus the tail clamped together. I hoped to have the firewall in also but discovered I have no m4 t-nuts, so am awaiting some more. They wont get here until Thursday most likely so I hope to have most of the wing done by then. yeah right....

Oh and I have all but given up on the steerable nose wheel idea. The firewall and tank bay seem to tight on this model for all the required hardware and pushrods. Has anyone managed to do this and care to share?

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No, I couldn't see a way of doing it without having the link and arm mounted externally below the fuselage. It doesn't steer too slowly on rudder with some up elevator to unload the nosewheel. You would need to use a motor mount that could be drilled to hold the leg and allow it to pivot, but as you've discovered there's no room for an internal tiller arm.

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Hi Jack, One big advantage of wing mounted aileron servos is that it neatly gets
around an error in the design of the kit - the wing mounting bolts will foul the aileron
torque rods if it is built without modification. Perhaps this problem has been fixed
in latest kits.
A fixed u/c does avoid a lot of building faff.
Try not to get the tail end too heavy. smile

 



 

Edited By Richard Wood on 08/03/2016 09:01:13

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Yeah, my last one had the issue with the mounting bolts fouling the Aileron servo. This is part of the reason I am going with servo's in the wings.

I will watch the weight of the tail certainly. I should have some latitude though as I am using a fairly heavy engine (SC 46) and will have an alloy spinner on the front most likely. I can alter the size of the flight pack to assist if I need to as well.

I put together some servo boxes last night but might re-do them. I had planned on having the ply servo mounting plate flush with the wing veneer by sitting it on the rim of the servo box, which would be sunk below the level of the wing veneer. However, it occurred to me over breakfast that it makes more sense to have the balsa servo box top level with the wing veneer (and sanded flush) and the servo mounting plate sunk inside the servo box, screwed to hard wood posts. This will ensure a tidy fit right up to the veneer, with no foam showing, even when the mounting plate is removed.

I will have a play tonight anyway and decide.

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  • 4 months later...

Wow, 3 months since an update. I have now done some more work on this (most of it in the last week or so) and am close to being able to cover it. I am trying to get it ready for the UKCAA meet on Sunday. Not too sure I fancy doing the maiden flight in front of everyone but we will see if it is even ready!

 

bullet replacement

And, yes, that is blood on the fuselage. Serve me right for using a david plane at 11pm  

Edited By Jack Banner on 18/07/2016 16:15:03

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  • 11 months later...
Posted by Richard Wood on 08/03/2016 08:59:47:

Hi Jack, One big advantage of wing mounted aileron servos is that it neatly gets
around an error in the design of the kit - the wing mounting bolts will foul the aileron
torque rods if it is built without modification. Perhaps this problem has been fixed
in latest kits.

Edited By Richard Wood on 08/03/2016 09:01:13

I know this is an old thread but I wish I'd read it before I started putting mine together because I can absolutely confirm this little problem has NOT been fixed - I went for a single servo in the interests of originality and am now wishing I hadn't...

I was thinking a Thunder Tiger PRO 46 might be suitable, or might that be a tad too much?

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It is an easy choice to make Tim, but as you found on a low winger

A single center servo is smack dab exactly where you don't want it, and it needs room to move.

The great thing about wing servos is they are located in the c of g area where any weight penalty is easily lost, and

you then have control over differential if required.

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Hi Dennis

Yeah, I know about the advantages of separate aileron servos, having been flying mostly F3f type gliders for the last few years - its partly as a reaction to that I went for the "simplicity" of the original set up.

I've never found differential to help with a symmetrical wing, TBH, but as Bob says, these old models tended to roll quickly anyway - although a slow roll is sometimes required.

I've done it both ways - built an 80% Challenger with a single set-up and both an 80% Mach1 and KF 4/40 with a pair of side mounted HS 85MGs in the wings. What really winds me up is that I built an original Crescent kit back in about 1987 - and I'm pretty sure, now I think about it, I had exactly the same problem back then!

 

Edited By TIM Shaw on 07/07/2017 17:17:31

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Posted by TIM Shaw on 07/07/2017 14:37:53:
Posted by Richard Wood on 08/03/2016 08:59:47:

Hi Jack, One big advantage of wing mounted aileron servos is that it neatly gets
around an error in the design of the kit - the wing mounting bolts will foul the aileron
torque rods if it is built without modification. Perhaps this problem has been fixed
in latest kits.

Edited By Richard Wood on 08/03/2016 09:01:13

I know this is an old thread but I wish I'd read it before I started putting mine together because I can absolutely confirm this little problem has NOT been fixed - I went for a single servo in the interests of originality and am now wishing I hadn't...

I was thinking a Thunder Tiger PRO 46 might be suitable, or might that be a tad too much?

Disappointing that they haven't sorted out that out yet.
On my 1st Bullet build - when it was too late to do much else, I resorted to installing
dowels in the fuse for rubber band wing fixing. 2nd build I moved the wing bolts back
to clear torque rods.
It'll live up to its name on a powerful .46!

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I'm thinking that if I ditch the spike nuts and go for tapped hardwood blocks - which I prefer anyway, I can probably get away with it.

I have a choice of engines available - OS 35AX, OS 40, OS 46 and an OS 55AX as well as the Pro, but although the Bullet is a little smaller than my 35/36 powered KwickFly and Challenger, its also going to rather more bulky and quite a bit heavier, so I'm leaning towards the Thunder Tiger. I can of course always throttle it back......

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