1:5th Scale Spitfire

[Jason Griffiths]

Hello everyone just thought i would post my project on here for all to look at and help me with.

It's a Pica 1:5th scale Spitfire and at the moment iv done the rear fin/rudder and elevator and half way through doing a wing section,but iv come to a point at fitting the retracts where i need some advice.

Retracts are Unitracts for the Spitfire but the problem is fitting them,iv got them fitted at the moment but the wheel well has jumped up a rib and not as on the plan,so do i more the retracts more to the centre of the wing or leave them as they are !!

I was just thinking if i moved them more to the centre would it sit/look right when it's on the ground and would it make landing harder as of making it narrow !!!

Also i need air line,filler valve & contol valve for the retracts.

Heres a few pictures

[Mike Booth]

Looks good so far Jason.

My advice to you is to leave the retracts where they are and worry about the wheel wells after you have built the rest of the wing panels and sheeted the top.
It is crucial at this stage that you concentrate on creating two panels that are the same and that they have equal washout.
Make no mistake Spitfires are fine performers if you stick to a few basic rules.
One of which is sufficient washout.
The fullsize had 2.5 degrees and it wont hurt at this scale to have 3 degrees.
You will be rewarded with a model which behaves its self perfectly near the stall.

With regard to the retracts; if you are building a scale model then this is what you want it to look like when it is finished.
Despite the fact this is a kit ,it wouldnt hurt to have some scale drawings around to influence your decisions.
If you have the retracts in on the bearers marked on the plan, then set them up here for the correct operation and angles and then adjust the wing skinning around the retracts when you are happy.
What you want is to end up with ( in Leymans terms) the legs sticking out in the right place.
You dont want to go compromising the strength of that mainspar.

I have used Unitracts exclusively for 17 yeras on my Spitfires and i think the standard is superb, this involves thousands of flights including my current 1/4 scale models.
I couldnt recommend them highly enough.
I used a foreign make in the past for two Mustangs and there were always issues with the operation.

I hope this helps, looking forward to more.

Mike.749

[Mike Booth]

Jason , just one other thing.
Knowing retracts and Spitfire angles as i do , that unit in the picture is in the wrong wing panel.
The oleo is set up to touch the rear face of the mounting plate so that it sits in the wheel well at the right angle.
The area of bearer plate that is machined away on the corner should be at the front.
Correct me if i am wrong but mine have always been the other way around..

M

[Jason Griffiths]

Hello Mike,

Thanks for your advice it's a very big help to me as this is my 1st scale Spitfire build.

Iv had a play again tonight and cut a little more out and now got the right retract in the right wing panel (Thanks again Mike)

As for the washout in the wing iv done it as plan so fingers crossed it's right.

Does this look better Mike

[Mike Booth]

Yes that looks ok now. I can see there is some additional vertical webbing on the front of the spar , i would continue that through on the next bay between the ribs , just to be sure.
Also add some more material around that rear bearer on the rib, as this is the point under most load on touch down.
it would pay to use epoxy in this area if you are happy with the oleo angles.
If you have a little tolerance between aluminium and wood, you can pack the unit with washers, under the rear plate if you need to get the forward rake on the legs a little further in front of the CG, helps to stop nosing over.
That covered it looks fine.

M

[Jason Griffiths]

Iv just start the other wing panel tonight,ill have another play with that retract in the next few days and add more strengh to the rear.

Top man Mike

[andywynn]

Hi Jason,
Don't know the Pica Spit, and there is no doubting that Mike is the oracle of the Spitfire but the retract units should be mounted in the flat centre section and then retract into the outer panels? Just wondering if that is the cause of the problem.
Good luck with the build. Another thing to remember about the early Marks of Spits is they all (till the 9) had relativley short noses and pretty much every model i have ever flown has needed lots of lead to balance. If you try to keep the tail as light as pos and don't be scared to add weight at the nose this will help. Remeber the difference of moment. If the difference between the C of G and the tail is 4 times longer than that from the C of G to the nose then for every Ounce added at the tail you will need 4 in the nose to balance.

Cheers

Andy Wynn 1313

[Mike Booth]

Andy is right there Jason , and has explained things in a slightly clearer way.
The bulk of the retract unit is in the flat centre section of the wing as he says, though its difficult to see from your pictures what part of the wing you have these in.
I have assumed you followed the plan which may be different from 100% scale?

Is the boxed area the wheel well?

He is spot on with comments on CG, weight etc.
You want all of the servos as far forward as possible and nothing in the tail.
I have a Post Office card through the door, so i will collect and take a look at the drawing.
M

[Jason Griffiths]

Andy thanks for your advice and the information.

Right looking at the retract and were it sits in the wing section at the moment it looks like it's at it maxium towards the centre of the wing section and the reason i say that is because when the retract folds out it looks very close to the main spar and in order to get in more in the centre section of the wing i will have to cut the main spar.

Over the weekend im going to have a play with the retracts again and now iv got my airlines and air vavle etc (thanks Phil) im going to see if they do catch or not.

Im nearly at the same stage with the other wing section now so come Monday i should have both side uptoo the same point then just the centre section to build.

Yes Mike that boxed section is for the wheel wells but if i leave them as they are it's going to jump to the next rib up.

As the the cowl im not fittng the Pica standard cowl which comes in 2 half and note like a Spifire cowl iv brought a very nice cowl off a friend with exhaust fitted and scoop and cut already for the motor just will need repainting.

Yes mike i think that will be my package i hope the drawings are ok to work from.

Also the kit is not scale there are a few bits which are well off.

[Jason Griffiths]

This is what the plan shows for the retracts

[Mike Booth]

Jason, looking at this latest picture of your plan , its worth asking yourself how the axle point at the end of the oleo looks compaired with the position shown on the plan.
Looking at the drawing and what you have built suggests that the centre point of the wheels will be too far out.
Correct me if I am wrong.
It would be easy to judge with the wing panel over the drawing.
M

[Jason Griffiths]

Yes Mike if i leave the retracts as they are now when the wheels are folded away they will be into the next rib up,unless i move the retracts in about 1" towards the centre section then they would come right.



Iv just took this picture which gives you a better idea on what i mean.



So what do you think Mike move the retract more to the centre section so the wheels sit in the right place with the plan ??

[Bob Thompson1894]

moving the retract more to the centre will make landings that little bit harder- may be a simple answer would be to have the oleos reduced to the correct size on the plan?

[Jason Griffiths]

moving the retract more to the centre will make landings that little bit harder- may be a simple answer would be to have the oleos reduced to the correct size on the plan?

Hello Bob i did think about this but as this is my 1st scale Spit build i was not sure which route to go down,thats why iv posted on here,to get all the help and ideas from the best people in the world

The overall oles leg lenght is 165mm.

[Bob Thompson1894]

Mike is the man to talk to about Spitfires, Just my opinion that the narrow track on a Spit makes landings awkward enough without decreasing that size, even a small amount? Dont get wrapped up in the whole 'superscale' thing, the Pica Spit is nice, but not exact, just do a good flying model, no-one will know if you have a working altimeter or not as it screams past on a low pass!!!! The other Spitfire on this forum is being built by a highly professional model maker for Top Gun USA- we can take inspiration, (and turn green with envy) but dont try to emulate, you will be bankrupt and divorced before it is done!

[Jason Griffiths]

Hello Bob

It looks like iv got 4 ways of doing it now lol

1) move the retracts more to the centre section so the wheels sit in the right place of the plan.
2) leave retracts as they are now and move the wheel well up a rib.
3) use shorter oles and leave as is.
4) put the fix u/c on

Iv just started on the middle/centre section this morning.

[Bob Thompson1894]

no no no. its only 3. Fixed u/c on a Spit? Build a Lowly.

[Jason Griffiths]

no no no. its only 3. Fixed u/c on a Spit? Build a Lowly.

lol calm down Bob i was only messing ill put the 4th one on hold .

[Phil Clark]

Correct me if I’m wrong here.....but...........

Many sports scale spit kits have had their gear positions moved outboard a little to widen the track to improve ground handling.........BUT......the wheel wells have been kept in the scale location, meaning oleos of shorter overall length are required.

This is no bad thing as shorter legs have less leverage and will therefore put less stress on the gear mount rails in the event of a heavy landing. The down side (as far as the scale visual appearance goes) is as the struts are shorter, the sit on the ground is incorrect as the model is now sitting 'flatter' rather than the 'nose high' angle is should have. Sitting flatter can also help you as models with their noses stuck up in the air, especially ones with narrow gear can be a real pain on the ground (Spits and Me109 are prime examples)

It's swings and roundabouts on kits like this.......you can leave them be and accept they are not perfect, or start chopping things about giving yourself more grief in trying to make a sports scale model more accurate.

Personally, if this is your 1st large Warbird build, I'd leave well alone, get Unitracts to shorten the struts for you to match the plan and build it exactly as it's shown on the drawings.

Phil

[Jason Griffiths]

Hello Phil

Right iv just placed the retracts in there position in the wings and there is a 1mm difference in them which is not too bad with all the cutting iv done to them.

Like i say if i get the oles shorten by 25mm then they would be correct with the plan position.

I was going to use a 4.5" Spit wheel on them.

Just like to all the guys for the info it's great to have it along with your feedback please please keep it coming it's a big help.