Topic: 1/4 Scale D B Sport Scale Sopwith Pup Build

Finished the tail plane and elevators, I was going to start on the fin and and the rudder, but since the plan I was working on also has wing Centre Section I decided to do that instead and get it out of the way.

I was hoping to glue all the parts of the centre section this evening, but after spending over 45 minutes looking for a part, I lost enthusiasm and will carry on tomorrow.  The centre section is only dry fitted at this stage.  What takes time sometimes is identifying parts quickly (Eddie is considering addressing this issue) All that is required is to provide a key e:g B=Balsa P=Ply HW=Hard Wood etc etc So when the part is mentioned say part 212C it should say in the instructions 212C (HW)  that way you are not hunting through the box looking for it in balsa bits.  I  looked at every balsa part about six times (I was convinced it was balsa) and after 45 min found it when I was packing things away.

There are four 8 gauge wing joining rods per centre section  one end hooks in the hole of ply spar and the other end exits through the hole in the outer ribs 

because internal bend of the rod is rounded (the bend that hooks into ply spar) when it exits the the outer rib it is not at 90 degrees.  To solve that problem you simply need to elongate the hole in the ply so that you can push the rod further in and it will then exit at 90 degrees in relation to outer rib.

This would have been obvious had you decided to build the wings first as it is mentioned in the wing building instructions.

Point taken, however the only race I have is against time.  I want to get to covering point before the cold weather sets in so that I can get my car back in the garage.  Doesn't matter what kit you build there will be and have been times where fraustration sets in, might I add in 90% of cases the fraustration is self induced, as you rightly point out if I had built the wings first I would have realised the part 212C were not balsa.

If you are still not receiving notifications from both the forums then it has to be your PC, your browser settings etc, you may wish to download free Firefox browser and use the firefox to access the forums and see if that helps.

Wing Centre Section

The upper centre section is done and waiting to set, while I have the plan on the board I will attempt to kill the bottom centre section this afternoon.

I am hoping to be building and finishing at least two main wing panels by the end of this weekend.  I want to get to a stage where only covering and other cosmetic work is left to do before it gets cold, as I need to reclaim my garage back for the car..

Now I mentioned the squareness of the wing joining rods in the centre sections, photo below will explain more graphically where the words may have failed.

What's the tape binding before gluing on the rods about?

What's the tape binding before gluing on the rods about?

A method introduced to me by D B Sport and scale, used it in Hurricane and the Spitfire, provides and extremely good bond between ply and any metal rod, using cyno or epoxy.

Alan H

Cheers Eddie, I will try that 

Thanks Alan,

Please don't think I was having a go at you, I know things can be a niggle.

Hey, Surprise! Surprise!

Maybe the techies spotted my post about notifications and I just got one, either that or the log jam shifted off the line.

Eddie. :colm:

No not at all I didn't take it in any other way,  if I was a woman I could attempt to blame it on the wrong  time of the month, but even that wouldn't work since I am on the downhill run of 50   

Once the top centre section was dry it was turned over and 4 x ply supports glued in place.




The bottom centre section was constructed which is very similar to to the top centre section but it's a lot smaller and a little fiddly.  Now bearing in mind the top centre section is wider than the bottom one, it stands to reason that the top wing panels will be shorter and the bottom wing panels longer in span.

Carried on with the lower centre sections with various infills etc and also fitted the dowels, but before I did that I dry fitted the centre section with unglued dowels to the fuselage.

Need to sheet underside of lower centre section, but I can't seem to find two ply plates for the wing bolts, I am taking a break now until tomorrow.  I will hunt for the ply plates when I am fresh.

Also need to fit the undercarriage rear mounting ply plates before the bottom sheeting goes on, these wold be near the centre of the wing chord I believe unless the MKII has changed?

Hello Alan,

Reading your latest posts revealed to me that I have boobood. There are no additional ply parts for the wingbolt area in the lower centre section as you thought. It is in fact a balsa reinforcing block that fits immediately in front of the rear spar on top of the lower ply sheeting. The part number is 215, it is a thick balsa 1”x 3/4” x 3” compression block that you cut in half to fit both sides.

I confess that this was not in the new laser kit instructions, nor clearly indicated on the plan. That has now been corrected. The balsa block however, is supplied in the kit, you will need to drill it after fitting (SorrY)

No problems I have cut 5mm ply from one of the off cuts and fitted that instead with reinforcement gusset inside.

Alan H

Also need to fit the undercarriage rear mounting ply plates before the bottom sheeting goes on, these wold be near the centre of the wing chord I believe unless the MKII has changed?

yes thank you, I was aware of it. I was going to fit both at the same time, it is now done.

Alan H

Upper Wings

Started the upper wing construction, this is very involved and will require every ounce of  your concentration. The wing is constructed flat on the board with the leading edge packed under by 1.5mm (I used some balsa sheeting).  The bottom spars are aligned  with the plan as well as by temporarily dry fitting various ribs to get a nice snug fit.

There are a lot of things to think about.  I can assure you there will be a lot of head scratching initially to work out how the system actually works (should I say how it’s put together so that it works in the manner it was designed)

You must remind yourself if it’s the top or bottom wing you are building and check and double check with the plan, the instructions and the actual part you are working with.  Particular attention must be paid to anchor plates for the inter-plane struts as these come in three parts two of which are to be laminated and the third is fitted upright at 90 degrees angle.

The ones for the upper wing are different to those for the lower wing (they are numbered accordingly) with instructions as to what part laminates where.  The anchor plates also house the magnets, the two halves of magnets each has two tabs to secure it to the anchor plate by inserting the magnets into a recess in the anchor plate with slots for the magnets tabs which you bend over on the other side to secure them.  One half of the magnet has tabs with holes drilled in the tabs, these go on the strut (the holes are there so that you can secure them to the strut)

Close attention must also be paid to the bottom spar, as it has a gap to accommodate the trailing edge anchor plate.

The plan states that the Lower wing  dihedral should 1.5 inches measured at the wing tip and the Upper wing has a dihedral of 1.25 inches again at the wing tip.  However when you look at the plan there is only one root rib template, and that got me scratching my head.  If you remember from earlier post that the wing panel span bottom wing from the centre section is longer than the wing panel of the top wing which has a wider centre section, that is why the same root rib template gives you two different figures so don’t go looking for a second template (like I did) there isn’t one.

The ailerons are constructed at the same time as the wing construction but does not require to be constructed flat.  This is constructed  on the aileron spine all numbered to take corresponding numbered ribs.  The aileron control horn is fitted sandwiched between two ribs with lugs sticking out from the top as well as the bottom (it’s a pull pull system) The first panel was the hardest, a big learning curve, the rest should be a walk in the park.

I have had quite enough of the wing for today so more will be tackled during the week.

You must remind yourself if it’s the top or bottom wing you are building and check and double check with the plan, the instructions .......

You should try building a 1/3 Triplane with no instructions then ......

Anyway, it's looking very nice Alan and coming along in a speedy fashion

Alan B

Are those ribs lire ply or balsa?  How thick please?

Are those ribs lire ply or balsa?  How thick please?

If I remember correctly, all ribs are 3/32" balsa except for the tip rib which is 1/8" balsa with the rear top botom spars  spruce and athe trailing edge is spruce too.

Alan H

Hi Alan
Just dropped onto this thread, You making a nice job of this build, I note Pupcam, and Eddie amongst others are  on here as well, looking at the photo's it looks like you are well on the way for a nice flying aircraft. I managed to warp the wing on my aircraft, "I left the wing in the sun to dry in Portugal " ! Even saying that she turned out to be and still is a lovely flying aircraft. Keep the good work up !

Dave
Ps if you go to the links on the DB Sport web page there is a video of mine flying there.

Ps if you go to the links on the DB Sport web page there is a video of mine flying there.

Hello Dave,

Yes I have seen that video very nice too.  Open fires are great for unwarping the wings (dare say you have open fires in Portugal)

However I would try leaving it in the sun for a while instead, pick it up slightly twist the opposite way to the warp (hold it there and move it to a cooler place until the covering has cooled down) and that should unwarp it.

I have employed similar method to a friends wing when I was serving in Singapore for a while and it worked.

Alan H

Upper Wing continued

The wing tips are constructed flat on the plan on their own, when set they are later fitted to the wing panel.  The front edge of the assembled tip sits on the top surface of the leading edge.  The rear part is positioned so that the centre of the tip is in line with the centre of aileron spine.

The wing tip is further supported by scrap balsa infill sandwiched between the top and bottom spars.



The photo below shows the two anchor plates, the rigging gripper shown requires a tube fitted to extend the length of the release plunger for ease of use.  The new rigging gripper will be available in a few days which has a longer plunger.  Eddie is sending me the new rigging gripper.

I have plans for the old grippers, with a bit of modification you can turn it into a quick adjusting pull pull cable at the servo end.



The photo below shows the leading edge anchor plate fitted to the wing, the magnet is on the underside of the wing, which can be fitted after gluing the anchor plate or  after removing the wing from the plan.  You must use the correct magnet half, the one with the holes drilled in the tabs are for the strut end.





A quick view of the wing joining and quick release mechanism below:

Just a few more photos that explains the rigging system

Bottom Wing

With the starboard upper wing done I started on the bottom starboard wing, however not wishing to bore you with what will be a repeat construction, I will only post images of bits that are different from the top wing. Apart from that the bottom wing is slighly longer in span

Ailerons

I didn't show the construction of ailerons on the top wing so decided to start with the aileron construction, which in most part of it is almost free hand.

Starboard bottom wing is 90% complete the wing tip is glued together waiting to set and will be secured the same way as the top wing. All the infill for aileron hinges and the wing tip as per the top wing.

The differences in leading and trailing edge rigging anchor are shown in the photos below. Unlike the top wing the bottom spruce trailing edge spar is continuous I was hoping to finish all the wings by this weekend but that is not likely as I have to go to my annual Army reunion up north this Friday, back on Sunday.

coming on great allan...

allan i came home from work today in too much pain with my neck and shoulder.....my build will carry on but a bit slow....looks like i will be buying the burger and coke LOL ....

Sorry to hear that I am away this weekend to Army Reunion up North so not much will be done until next week.

Rudder & Fin

I removed the starboard wing from the plan and was about to change the plan to Port wing plan, and noticed that the plan underneath was fuselage plan with Rudder & Fin on it so took the opportunity to construct those there and and then.

The construction of rudder and fin are very easy and straight forward. Infact I built the rudder freehand over the edge of the building board so that I can glue in the rudder control horn at the same time.

Both rudder and fin construction is pre-cut laser parts numbered and fit nicely.  Only took 30 min from start to finish for both the rudder & the fin.

Correction

The anchor split pin shown earlier on the bottom wing trailing edge top spar should also be fitted with two brass tag anchor points (see photo).

I was able to rectify it since I had not yet glued the infill between the spars.

Port Upper Wing

Having constructed top bottom starboard wings the port wing was easy.  It only took me 50 minutes to complete the upper port wing less the ailerons and the tip (the tip is constructed and drying)

I will not bore you with repeat photos of wing construction but will point out one or two things with photos, that I mentioned in upper wing but did not show photos.

The photos below will show why the bottom spar on the upper wing has to be in two parts and hopefully you can see how the anchor plate fits there.  Also a bit of filing required on part 223C of the leading edge anchor plate to ensure that it doesn't sit on the bent over magnet tabs and is flush with the bottom anchor platform.

I will not be posting until next week as I am away tomorrow to my Army reunion (to prop the bar up for a couple of days  :colm:

Hi Alan
I've really enjoyed reading this thread and the skill of your building.  Top build and a top kit, I'm lucky enough to live just up the road from DB HQ.  Great to see Eddie on the forum.

Regards from another ...
Alan (J)

Aye Up Alan lad,
Nice to know that locals keep an eye out (aint sold you no balsa for a bit! are you still building?).

Need to update the footnote for the Welsh Air Ambulance, it needs next years date.

See you around, Eddie.

Hi Ed
I'm waiting to hear the total that we raised so I can publish it.  I'm building mainly in foam at the mo - want to enter next years BMFA 60" slope pylon.  And really sorry to newalan for hijacking your build thread.

Best regards

Alan

Newalan,

Ah you have picked a quality kit here... Ive got the pup and the cirrus moth 40 and both are superb. Compared to other 1/4 scale kits, theres no comparison in the UK in terms of quality of wood and ease of build.

I use a zenoah g26 magneto and it fits inside the cowl surrounded by a Mick Reeves dummy engine. Flies at 1/8 power using an 18/8. Only needs 1/3rd throttle to go into combat mode! About 17 llbs all up. A g38 is too much power. MVVS are good engines but have a noisy bark compared to others. I was going to get one for a Fokker dr1 im buildinig but not after hearing it run!


Loads of pics if you want them!!

Hi eddie, adam chambers here. you have pics of my moth on your site. Hope alls well. Have you got the SE5A redesigned yet?

I use a zenoah g26 magneto and it fits inside the cowl surrounded by a Mick Reeves dummy engine. Flies at 1/8 power using an 18/8. Only needs 1/3rd throttle to go into combat mode! About 17 llbs all up.

Good match of engine 

A g38 is too much power.

Wrong, it's also a good match, many will tell you this.

Good match of engine 

Wrong, it's also a good match, many will tell you this.

I got a 1/4 Mick Reeves camel on a Z26, excellent match.

I had a Z38 on a DB Pup, really excellent match.

Newalan,

Ah you have picked a quality kit here... Ive got the pup and the cirrus moth 40 and both are superb. Compared to other 1/4 scale kits, theres no comparison in the UK in terms of quality of wood and ease of build.

I use a zenoah g26 magneto and it fits inside the cowl surrounded by a Mick Reeves dummy engine. Flies at 1/8 power using an 18/8. Only needs 1/3rd throttle to go into combat mode! About 17 llbs all up. A g38 is too much power. MVVS are good engines but have a noisy bark compared to others. I was going to get one for a Fokker dr1 im buildinig but not after hearing it run!


Loads of pics if you want them!!

Hi eddie, adam chambers here. you have pics of my moth on your site. Hope alls well. Have you got the SE5A redesigned yet?

Very nice, I thought Mick Reeves only did 1/3 scale pup dummy engines?  I will have to investigate.  Eddie is still working away on SE5 as I understand.  that is my next project

Alan H

Just a thought, if those magnets have enough power to hold th inter plane struts in position could they be used as an alternative to the spring steel affair which holds the wing panels to the centre section 

Just a thought, if those magnets have enough power to hold th inter plane struts in position could they be used as an alternative to the spring steel affair which holds the wing panels to the centre section 

Understanding the forces involved or imposed on the the inter-plane struts will make you realise that the magnets are more than enough.

Forces imposed on the top/bottom wings are more or less equal on each panel, by tensioning the rigging wires on the ground  one is introducing a compression load on the struts, this compression load is further enhanced when the aircraft is flying.

This is a direct result of the flying wires  being  subjected to the flying loads transmitted to the the top wing, meanwhile same amount of flying load from the bottom wing is transmitted through the inter-plane struts.

The lower wing will push the load  through the struts, therefore increased compression on the struts as well as increasing tension to the ground tensioned flying wires.  It therefore stands to reason that the struts are always in compression therefore the power of magnets has very little to do with it.  The magnets are just a means of quick connection between the top/bottom wings.

The above is further explained in details on the D B Sport & Scale website.

 http://www.dbsportandscale.com/How-rigging-works.htm

Alan H

The magnets are just a means of quick connection between the top/bottom wings.


Alan H

I do understand the forces which does not explain why I have seen some struts that have simply a pin in socket come out in flight.

Anyway; that was not my query, I was not doubting their affectedness,  rather I was wondering if they would be strong enough along with the rigging which also pulls toward the fuselage as well as vertically would be strong enough to negate the need for those clever spring steel retainers 

I was wondering if they would be strong enough along with the rigging which also pulls toward the fuselage as well as vertically would be strong enough to negate the need for those clever spring steel retainers  

The proof of the pudding is in models already flying with the system.  The spring steel retainers can't work for the reason that the model employs 4 different wing panels pushed in from the side to locate into their spring steel retainers located in the centre sections.

To use spring steel retainers for the struts  you would need to force the wings apart by at least two inches whilst still attached (not very practical if not impossible), or you would have to unbolt the  centre sections to fit them in either case it defeats the object of quick rigging.

As for the pins coming adrift in mid flight, I can only assume that the part in question was not fitted correctly or indeed a bad design..

Below is a video of the model using the system built and flown by a German guy. Flown using electric motor with digital dubbing of engine sound
D B PUP Video Germany

I think perhaps you are misunderstanding what I am trying to say.  I was thinking the magnets could be used instead of the sprung wing retainers, nothing to do with the struts, the wing panel to centre section join is what I'm referring to.

Just a thought, if those magnets have enough power to hold th inter plane struts in position could they be used as an alternative to the spring steel affair which holds the wing panels to the centre section

I see,  reading it again I think I now know what you mean.  No I don't think the magnets would be man enough for the wings I think they only have a 1.5kg  pull.

Alan H

Update

The fourth wing panel is finished and drying. I will fit the servo bay and the wing retainers on all 4 panels next and probably cover them provided the new rigging gripper are with me soon.

I have been a little busy so very little work done.  The engine will be purchased in the next two weeks.  (A free engine)  well not entirely free, I buy most of my engines by financing it through some wheeling and dealing.

I have number of car dealers who I provide IT support and websites to.  When they buy cars from auctions, most of the cars have a Haynes manual in the boot which they keep for me and every 3 months I collect something like 60 – 100 manuals for free which get sold on eBay for £4 or £5.

Nice little earner for the hobby.  So if you have a free source for these manuals you now know what to do

Alan H

Eddie,

I can get the pup ready in about 15 mins even with struts, wires and u/c connections.

Self tappers and a power screwdriver!!

norfolk mate,

dont flame me for having an opinion... learn a few forum manners. As per the manufacturers recommended engine set up, a g26 is adequate as rolls royce say. If you need a g38 , your model needs a diet!