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Tony Nijhuis 63" Spit

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Graham Eccles09/12/2007 10:18:00
18 forum posts

Keith, my Spitfire still not complete but for your information I am using the Unitracts De-luxe sport retracts c/w sport oleo legs and Robart scale diamond wheel 3.25" diameter. When retracted the wheels are locked up against the inside of the wing skin, i.e the bridging piece on rib W4 removed completely. I found you can reduce the width of the wheel slightly by turning the hub round. I fitted the retracts (temporary) and did the wheel well prior to sheeting the bottom surface rather than doing it when the wing completely skinned. To reduce the size of the wheel well I angled the walls back at the retract angle which appears to work ok.

Hope this helps

Martin McIntosh09/12/2007 16:27:00
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3572 forum posts
1231 photos
Keith, I cannot understand the quoted 24mm depth. The maximum depth of mine are 39mm from underside skin to the inside of the top skin with all rib parts removed from the well. It is built to plan.
KEITH MARSON09/12/2007 19:42:00
28 forum posts

Hi Graham and Martin, the 24mm measurement was the distance remaining for a wheel taking into account the sport oleo legs and leaving rib 4 intact, this is going by my plan,by removing the support section of rib 4 as you suggest then i have 39mm for both leg and wheel to fall into.

Question? is this suggested on the plan somewhere and i have overlooked this critical point or is this the only way you got  your wheel arrangements to fit,noting that you both have different configurations,you both also use Robart wheels which are 25mm i have Du-Bro which are 31mm which is where the problem  first started.

thanks for the info i will plod on.

Martin McIntosh09/12/2007 20:56:00
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3572 forum posts
1231 photos
No, the plan does not suggest this but it is a rather advanced type of model and I think that Tony assumes that we have experience. Having said that, if you can install Spit. retracts you should not have trouble with any other type so persevere. I have done dozens and lost a lot of hair doing them.
Shaun K07/01/2008 11:01:00
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192 forum posts
38 photos

Hi all, slow and steady progress sees me at the point of having the 63" Spit at the stage of two wing halves being top-sheeted, trimmed nicely to the outline, u/c mounts fitted etc, ready to put on the bottom sheeting if I was to follow Mr Nijhuis' instructions.

Before I sheet the bottom of each half, I'm now faced with the dilemma of how I would successfully clamp the two halves together at the final stages of wing construction, when a fully sheeted wing really gives nothing to put a clamp on.

I'd love some ideas here - is it best to clamp and epoxy the two halves before sheeting the bottom while there's plenty for a clamp to grab, or is there some clever way of getting a couple of flat sheeted surfaces pushed firmly together for a good bond with the epoxy?

Martin McIntosh08/01/2008 21:03:00
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3572 forum posts
1231 photos
Hi Shaun, in my view it is best to sheet the bottom surface of a wing before joining the two halves, ensuring that you have pull cords installed for the servo leads and cutouts so that you can get at them later, because this sheeting forms the all important last part of the `D` or triangulation part of the wing to prevent warping. You do not need to clamp anything; just ensure that each wing panel is packed up with blocks to the same height on each side, and you have the same measurements at the leading and trailing edges at the root and tip. If you have sanded the root ribs flat and to the correct dihedral angle there should not be too much of a gap between them and a liberal application of 5-20 min. epoxy will do the job. Just hold with pins. Apply a 2" wide strip of light glass tape around the join with epoxy or polyester resin and the job is done. Regards, Martin.
Shaun K09/01/2008 02:55:00
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192 forum posts
38 photos

Hi Martin, thanks for that. I guess my main concern is about the strength of the bond between the two halves if no pressure is applied.

Growing up in a long line of tradesmen/handymen that all tought me that any bonded joint will have a stronger bond if the glue/epoxy sets under pressure I've got this in-grained need to clamp stuff. I can't help it, it's in my jeans. Oops genes that is.

Clamping is also better when you have an inquisitive, mechanically inclined 3 year old wandering around that's prone to climbing the work bench for a look at the bits of dad's "spitwire".

I suppose if I truly can't fight the genetic urge to clamp I could cut a couple of small sections out of the top skin along the edge of the root rib that would end up getting glassed over and covered later anyway.

Martin McIntosh09/01/2008 12:36:00
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3572 forum posts
1231 photos
Hi Shaun, it is the glass cloth which holds the wing halves together. The epoxy is really just to hold them in the right place prior to glassing. MM.
Shaun K09/01/2008 23:04:00
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192 forum posts
38 photos

Thanks again Martin, much appreciated.

How is your own spit going? Still flying well I hope. You mentioned in a much earlier post that you changed the engine to a "smaller 53". What type of 53 is that - 2 or 4 stroke and is that what you're still flying with?

Martin McIntosh10/01/2008 12:45:00
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3572 forum posts
1231 photos
Yes, I have downsized from a YS63S to a YS53FZ since it was a little overpowered and I wanted to put the 63 back into another model. It also means that I can go down 1" in pitch which slows the landing approach considerably. I use a 13x5 Zinger wood. Martin.
Shaun K26/03/2008 13:10:00
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192 forum posts
38 photos

If anyone is still listening in here, I have another dumb question on this 63" Spit.

I'm up to the point of building the cowl and I'm thinking that once a fully built-up, fixed cowl is in place access to the engine mount bolts is going to be very tricky.

So what's the trick - do you simply bolt the engine mount in place with an abundance of thread-lock and build the cowl around it or do you build in access holes to allow the mount to be fitted in later or have you built a removable cowl?

 As I'm going to need to start thinking about covering soon too, feel free to comment on this thread too:
Covering with SIG KOVERALL

Graham Eccles26/03/2008 18:18:00
18 forum posts

Shaun,

I used Blind Nuts to bolt the engine mount to the front bulkhead and secure them to the bulkhead with a bit of epoxy, hex head capscrews used to fix the mount. Then I fixed the motor in position and built up the side cheeks, top decking and fillets ensuring they all clear the motor. When the above dry I marked the position the the front lite-ply ring removed the motor and sanded the front flat ready for gluing the lite-ply ring in place. Refit the motor and spinner and glue the lite-ply ring in place. I then added the bottom 12mm & 9mm sheeting to clear the motor (don't glue yet) removed the motor and then glued the sheeting into position. Sand the nose to shape and then start removing balsa until you can slide the motor back into position. For fixing the motor you need enough clearance to get a screwdriver between the motor and the side cheeks. You should have enough room through the front lite-ply ring to tighten the capscrews on the engine mount. I applied a drop of thread-lock on the capscrews on the final assembly.

Hope that helps.

Martin McIntosh26/03/2008 20:22:00
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3572 forum posts
1231 photos
Shaun, as is usual with my models, I made a glass fibre cowl which is not as difficult as it may sound. This is simply screwed to plastic angle mounts after engine installation, the only tricky bit being to get a spanner in to tighten a four stroke exhaust. Could reproduce these on a small scale if it would be worth my while re-stocking with cloth, resin, etc. The type of female mould I use can only be used a few times. I am no expert at this and cannot guarantee a professional product. If anyone is desperate I could possibly do these for around £20+pp. Remember that these will be shaped to fit MY fus., but are very flexible.
Shaun K26/03/2008 22:24:00
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192 forum posts
38 photos

Thanks Graham & Martin.

Graham - Your approach is exactly the sort of 2 steps forward, 1 step back approach I expected would be needed. I'm still not sure how I would get to the cap-head bolts through the nose ring tho - I'd need some longer hex drivers than I own.

I've been thinking about digging out the old box of fibreglass under the house - I might head down that path in the end. Many years ago I made a surfboard and vowed never to go near fibreglass again. I really enjoyed shaping the foam and found the glassing a tedious, harrowing experience... 

Time heals all wounds, so it might be time to tackle a cowl me thinks.

Martin - I've just had a look at your pics too - very impressive! Nice job. I'm planning to paint mine up in the famous Australian RAAF "Grey Nurse" paint scheme of Aussie ace Bobby Gibbes.

Photo of a flying example in Australia here.

Graham Eccles27/03/2008 06:51:00
18 forum posts

Shaun,

 yep, you need an long hex driver, I bought a cheap ratchet one from the local market stall many years ago. They only cost a couple of quid and useful for all sorts of jobs.

Good luck with whichever method you go for

KEITH MARSON10/04/2008 11:32:00
28 forum posts

Hi Guys

Just thought i would start this thread off again,i was wandering if anyone a had fitted a 3 bladed prop to this particular aircraft or if not would it be possible and what would be the size and obviously the set up problems.

I am intending to use an ASP.61 4 stroke with a 13x6 blade but thought a tripple blade would look better.

Graham Eccles11/04/2008 16:53:00
18 forum posts

Keith,

 Just Engines who sell the ASP engines also do a range of three bladed prop's and spinners. I suggest you send them an email and ask them what they would recommend for the Spitfire.

 http://www.justengines.unseen.org/acatalog/Just_Engines_Online_3_Blade__113.html 

Shaun K13/04/2008 12:20:00
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192 forum posts
38 photos

Hi Keith,

I've read plenty of theories on selection of 3-blade props. Most commonly I've seen two rules of thumb which both have keen supporters - one theory says take a suitable 2-blade and drop an inch off the diameter for a 3-blade, so your 13 x 6 would convert to a 12 x 6 3-blade.

The second theory is to both reduce diameter by 1 inch AND increase pitch by an inch giving you a 12 x 7 3-blade prop. For the record, before removing my ASP .61FS from it's current job of powering my old trainer I intend to trial a 12 x 6 3-blade and see how it behaves before testing uncharted waters in the Spit. I think the thing to be wary of will be that others have previously noted on this forum thread that a higher pitch also means a higher landing speed on the 63" Spit. Tony Nijhuis also mentioned he used a 2-blade 13 x 5 and never saw a need to change it.

Check out the site below for some interesting facts, rather than rules of thumb.

Bolly Web Site - Propeller Theory & Technical Data

Martin McIntosh13/04/2008 21:59:00
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3572 forum posts
1231 photos
Shaun, that Bolly website is brilliant and gives me an incentive to try a 3-blader on my Spit, thanks.
KEITH MARSON14/04/2008 20:14:00
28 forum posts

Hi Guys

Thanks for the info,my grandson certainly gives me some problems i wouldn't mind but i don't even fly the planes just build  them (ah well grandads for you),anyway having had a lay  off due to work commitments i am back in full swing for now, the wing is finished and i have started on the fuselage and i have another dumb question?how do i secure the fuel tank , is this another one of those hidden secrets i should know.

I am sure i will have a few more questions before i have finished but if someone could dish the dirt on this question i would eternally grateful.

thanks

keith

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