Topic: 1/3rd scale Sopwith Pup

Make it removable mate
My biggest mistake was not doing that. It takes up so much room.

Si

Make it removable mate
My biggest mistake was not doing that. It takes up so much room.

Si

Removable as in fin from tail plane?

Removable as in fin from tail plane?

Tail plane with or without fin attached will make a big difference. Its such an easy mod to do.They way Ian did it makes so much sense. Just copy that.

I will be taking the saw to my one soon.

Si

Ok removable tailplane it is then but not sure if I will make the fin removable or not.  I guess as the rigging holds it in place and square it only needs short pins to locate and hold it raised slightly 

I made up the elevators today they are still all in 1 piece without the hard wood joiner I guess have them as singles and a servo for each?



Top wing centre section covered and with 1 coat of dope on I think I may get away with only 2 if I don't thin it 1st and the paint will not pin hole everywhere 
Top wing panels are also pretty much repaired and fit for use......... non scale fat section with straight tips.  If I were building from new rather than a rebuild of an old one I would have done all the modifications but that will take time and I want to be flying it this year, this summer.  I guess there is no reason why I cannot cover the top outer panels if my fuselage material does not turn up for a few days?



I want to try and keep up the momentum and get it done.

As you say the rigging will hold the fin in position.
One servo per elevator half is the standard way to go.

Looking good Shaun. You are well on your way now.

Si

Hi Shaun

My tail is removable and flat packs .Its easy to do and gives a scale like fin/rudder. I will take pics in the morning .

Alan

Wheels.................... shame http://www.amazon.com/ARNOLD-490-323-0003-SPOKE-WHEELS-x1-75/dp/B002DZWX3M/ref=sr_1_cc_3?ie=UTF8&qid=1296326813&sr=1-3-catcorr are in the USA    mind you not light with a shipping weight of 3.2Lb

Not sure whether to get some Mick Reeves ones or make some from Ply pipe and a prayer. 

Hi Shaun

My tail is removable and flat packs .Its easy to do and gives a scale like fin/rudder. I will take pics in the morning .

Alan

Thanks Alan all knowledge is good you cant have to may pictures IMO 

Not sure whether to get some Mick Reeves ones or make some from Ply pipe and a prayer. 

Shaun. my mick reeves wheels are showing bad signs of wear... Can't bring myself to spend £30 for a new pair... Do us a favour, knock some up and show me how easy it is to make some.... I'll need to do the same for the floh as it will be an odd size...

In what way are the MR wheels wearing?  just a case of renewing tyres due to concrete runways or where the axle goes through needing a brass tube bearing?

I see it's best to have an access hatch on the underside of the fuselage is this just 1 from firewall back or between the next 2 bulkheads?

I guess the 1/8" liteply behind the rear undercarriage legs is glued in and not removable?

 I assume all servos will be as fare forward as possible near the firewall?

In what way are the MR wheels wearing?  just a case of renewing tyres due to concrete runways or where the axle goes through needing a brass tube bearing?

Where the axle goes through needing a brass bearing...

I always do that anyway 

Do you recall hatch positions?

Do you recall hatch positions?

I had three hatches, one on the top decking between the c/s struts, another below between the u/c legs, and one behind the rear u/c legs where my servos were, under the pilots seat.

Ian.

I had three hatches, one on the top decking between the c/s struts, another below between the u/c legs, and one behind the rear u/c legs where my servos were, under the pilots seat.

Ian.

Thanks for that Ian 

I guess you did not use a full 8 1/4" width hatch as this would have given little in the way of strength to the underside of the fuselage?  I was thinking put the bottom in and have the hatch hole say 1" all round from the edges both on the rearward hatch just below the pilots legs and the next one forward of that which is just in front of the rear undercarriage slotted ply fixing point?
I would imagine the front section that goes right up to the firewall would be 1/8" liteply glued in no hatch to stop the reduction drive removing F1?

Maybe I should take a photo and dray on what I mean I'm not sure I'm explaining myself well.

Also where the rear undercarriage support goes I believe you are supposed to cut the 1/4" square longeron out to allow it to go right up to the liteply sides is this wise and not better to cut the undercarriage mount round the longeron then put some sort of triangular section to beef up the mount to fuselage side    Mind you once the front liteply is glued in right up to the firewall I guess this is going to hold the fuselage straight.

I'm a little fluffy this eve and cant see the wood for the trees maybe it will al be obvious tomorrow once I have grouped my poop again 

Oh one last thing Ian, you said you cut the firewall to take the front cabanes and didn't add the liteply cabane mount just behind that is that correct?  It's not biggie to put the other mount in behing F1 at this stage but would be a sod laters if it's needed.

My hatches were full width. I boxed in the tank bay by putting a full floor half way up, at the bottom of the instrument panel level. The tank sat on this floor with a division in it for the Rx and batteries. The top hatch was cut out of the ply decking after it was fitted, leaving a good inch or so border and rounded corners. An ali panel was the actual hatch. I think the botom hatches were actually in three bits. A fabric covered one behind the rear u/c mouning, another just in front of it, with a fabric covered liteply one up to the front. This one had the V shaped ali trough in it, since I had a similar hole in the firewall for cooling.
Heres a couple of pics that might give info on my hatches. Just looked through and none show them that clearly.

Ian.

If you can wait until this evening I will get you a couple of pictures of my hatches.

Si

If you can wait until this evening I will get you a couple of pictures of my hatches.

Si

Waiting     

Should the stringers on the pups back be straight or evenly spaced on the formers?  if evenly spaced they will curve slightly and to me this looks wrong I think they should be straight 
Also on the kit plan (this has no former shapes and sizes) is shows the stringers finishing short of the tail plane.......... I don't see any reason for this and think it would look better running right the way back instead of the piece of balsa block to finish the end.
At this stage I have only cut the stringer formers, no slots for stringers yet + stringers have not been cut to length so anything can change right now.

The cowl.......... I am slightly concerned that Ceejay's cowls are 349mm inside Dia and the BUSA fuselage has a 342mm outside Dia not that easy to make up the difference unless I make the front formers larger and have the ply top deck between firewall and cockpit taper + side cheeks taper to 

This may help

Steve

and this

Cheers Steve for the rapid reply straight they will be    I will mark out for and aft stringers then pull a piece of thread between them to mark out the other formers 

All good things are waiting for me old mate

Both hatches


Rear hatch has the Elevator servos in. These are now Hitec HS645mg as I striped one of the 3010's in the air.
The RX is now a Frysky one.



Front hatch is acsess to the tank and Rudder servo. The batterys are now behind the pilots seat  as the 80cc twin was heaver  than the geared 38 set up.



Simon

Ref. the stringers. At the rear end, if you lok at the side skeletal view that Steve posted, there is a triangular fillet on the top longeron, just in front of the tailplane. This takes the covering line up to the tailplane leading edge, then straight across the fuselage in front of the tailplane to the fillet on the other side. This might be what gives the impression that the stringers end early since the covering isn't attached to them all at the rear end.

Ian.

Thanks chaps great information and pictures which tell more than you can explain 

ref stringers finishing before the tail that's how it's shown on the plan I do understand the wedge fillet to take the transition from fuselage side to tail.  From most of the full size pickies I have looked at the 1st stringer near the top of the longeron is actually parallel to it rather than evenly spaced out, looks like 1st one is the same distance from the edge then the other one goes between that and the centre one.
I see you had a different metal plate attachment on your picture "happy5" also shows under cambered wing tips and the tailplane with a aerofoil profile rather than flat plate as per plan.

I see from Simon's both bays the one from the firewall and next are all as one having just the 1 access door but still leaving plenty of meat either side rather than full width.  One thing I'm not over keen on is the closed loop going directly on to a servo I always feel this puts a lot of side strain on them........... never had one break this way but I dunno    Usually I make another pivot arm so the closed loop is all wired up the 2nd arm has a rod going to the servo arm but his does give another 2 links which is something else to wear I guess.

COOLING!!!  booga that's something I had thought about then forgotten!  I guess it all depends on the orientation of the G38 and from what I have seen from a few pictures the head wants to be at about 4:30 but I cant really plan that bit out yet as I have no reduction drive until April.  Also this cowl business .............. it seems Ceejay's ones are very slightly larger than the BUSA one    if push comes to shove it will get a cut and shut and a few rivets to hold it back together.

I done nothing today on the pup other than look and try to plan the next plan of attack which TBH was all a bit of a fluffy time seeing nothing!

Yep know what you mean about connection directly to the servo but I also like to keep it all as simple as possible. There are no links to fail fitting the closed loop to the arms, no slop, and you do not need the wires under much tension. Most of the servos we use now have ball raced outputs. That just the way I like to do it , it works for me.

Simon

Shaun,

This is my understanding of the stringers  at the backend (on the Tripehound anyway) according to the drawings I have.

There is a rectangular former ahead of the tailplane into which the 5 stringers are notched.  The centre one is essentially straight with the outer 2 pairs curved upwards to fit into the notches in the rectangular former. 

Although the Pup fuselage has different proportions I should imagine the arrangement is similar .   
HTH

Alan

Stringers almost done now........... phew seemed to take ages!

I have been thinking about how to modify the fuselage to accept the slightly larger Ceejay type cowl.  There will obviously have to be larger formers on the front then some buttering up down the sides and bottom of the fuselage before the cheeks are added.  I just done a quick picture to get it in my head how the changes will be I think keep them all to the bottom to keep the lines looking right.

Stringers done at last.





I cant do a lot more on the fuselage till I know the actual cowl diameter but there is plenty more to do.  I can repair the ailerons make the horns and cover them.  I think the top wing can be covered once the new hinge points are made to.  Also there is the rudder to make inc it's horns using that glass copper coated board Ian gave me I think there is enough to do them 

How much larger is it?  On my 1/4-scaler DB Pup, I replaced the 'square-nosed' cowl supplied with a Mick Reeves one, which was fractionally larger.  I got around this by just pulling it down at the bottom, so that the sides lay flush to the fus, then marked/drilled/screwed accordingly.

OK - the rear of the cowl is now actually a bit egg-shaped, but in practice, it's completely unnoticeable - and the hole for the exit draught is a little bit bigger...

Mike

Nice job 

Steve

How much larger is it?  On my 1/4-scaler DB Pup, I replaced the 'square-nosed' cowl supplied with a Mick Reeves one, which was fractionally larger.  I got around this by just pulling it down at the bottom, so that the sides lay flush to the fus, then marked/drilled/screwed accordingly.

OK - the rear of the cowl is now actually a bit egg-shaped, but in practice, it's completely unnoticeable - and the hole for the exit draught is a little bit bigger...

Mike

The BUSA one would be 342 outside dia, Ceejay's ones are believe to be (a check is being done with the new stock) 349 inside dia.  Assuming they are 2mm thick that makes the outside dia 353mm that's a circumference of 1109mm, the BUSA one is 1074.5mm so there would be about 34.5mm to much meat 

Now.................. with the Pup Alan gave me came a battered and out of shape cowl which has a large cut out (piece missing) but I may have found a solution to my problem 

http://www.standardmotorclub.org.uk/cars/military/features/sopwithpup3.htm

I will still need a cowl from Chris for the Bristol Scout so nor probs there I can still get that in April 

Looks like a solution to your problem there .
Good find

Si

Good job I have not fitted the firewall, the cowl I have is 135mm in depth and Mudders kindly gave me the mount to prop drive measurement of the reduction drive which is 175mm so I should move the firewall back what about 20mm    20mm gap between back of prop and cowl about right?

I cant help thinking "game on" after making the decision to go with the old cowl 

I really must learn to read all of the previous posts 

Looking good Shaun

Alan

Ian, ref moving firewall back 20mm, I recall you saying you cut slots in your firewall for the cabanes would that be because you moved your firewall back 20mm to it would make sense because the cabanes do not touch the firewall with it in the position shown on the plan.

Hi Shaun,

not sure if this will help but have whipped off the cowl from my "rugsley's" built Pup.... And took some photos..

Cowl is 170mm deep and 345 diameter

Photo's uploading and will follow in a mo...

The prop is quite close to the Cowl... and the lower picture shows the orientation of the engine...

My firewall looks like it is in front of the forward cabanes....

You may be able to see where the cowl overlaps the firewall on the litho plate...






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does this help, she's in bit at the moment so yell if you need more...