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Author Topic: Guillows kit 505 Messerschmitt Bf-109  (Read 2164 times)
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RolandD6
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« on: September 17, 2019, 06:32:31 PM »

Because my Sopwith Pup project will not be finished in time for the VFFS end of year scale day, I had a look at what was on offer at my preferred hobby shop when purchasing some Molotow Liquid Chrome ink for the Pup. To my surprise there was a reasonable choice of Guillows kits but I was wary of older type die cut kits. My last was back in the 1970s, an Albatros D.Va which was less than spectacular. It was my second attempt at a rubber powered model and I was somewhat clueless at the time, having only built heavyish C/L models beforehand.

Kit 505 is laser cut so I was hoping for the best since others have commented favourably about the new laser cut kits. The kit cost A$29.99 which I considered reasonable for my hoped for time saving. I also have hankered on and off to make some sort of model of the Bf-109E in Swiss colours.

On opening the contents looked neat and tidy so I set about measuring and weighing the wood and tissue with the following results:

Stripwood — nominal 1/16” and measured 1.6 mm (close) and weighs about 12 lb/cub. foot.

Sheet A — nominal 1/16” and measured 1.6 mm and weighs 12 lb/cub. foot.

Sheet B — nominal 1/16” and measured 1.6 mm and weighs 10 lb/cub. foot.

Sheet C — nominal 1/16” and measured 1.8 mm and weighs 10 lb/cub. foot.

White tissue paper — 17.4 grams per square metre, not exactly light.

A curious thing is that the stringer/spar slots in the fuselage formers and wing ribs appear to be about 1.3 to 1.4 mm wide, too narrow for the supplied stripwood. This may prove to be incorrect after I sand the ribs and formers down to 1.3 mm and test fit the stripwood.

More later

Paul
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RolandD6
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« Reply #1 on: September 18, 2019, 04:11:15 AM »

I found I needed to sand the laser cut sheets to a nominal 1.2 mm (allowing for spring back to about 1.3 mm) to get an easy fit in the various notches.

The original weight of eaxh sheet was:

Sheet A _ 7.02 gm

Sheet B _ 5.9 gm

Sheet C _ 6.5 gm

The reduced weight of each sheet is as follows:

Sheet A _ 6.11 gm, a saving of 13%

Sheet B _ 4.65 gm, a saving of 21%

Sheet C _ 4.76 gm, a saving of 27%

I cannot explain the variation between the % weight savings. Perhaps Sheets B & C sanded a bit thinner than Sheet A.

The adjustable sanding block appears in the photo below.

Paul

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Re: Guillows kit 505 Messerschmitt Bf-109
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ZK-AUD
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« Reply #2 on: September 18, 2019, 05:10:46 AM »

Paul whether die cut or laser cut those Guillows boys sure use load of wood in their designs.  A bit of happy time with your knife could see half of those keels and probably 2/3 of the formers in the bin.   There's almost no room for the rubber as it stands!
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RolandD6
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« Reply #3 on: September 18, 2019, 06:55:47 AM »

Paul whether die cut or laser cut those Guillows boys sure use load of wood in their designs.  A bit of happy time with your knife could see half of those keels and probably 2/3 of the formers in the bin.   There's almost no room for the rubber as it stands!

I am aware of that. My plan is to drum sand away as much as I can reach before adding the other side of the fuselage frame and the stringers. I have a pencil power tool which should be able to reach most areas. I did not want to cut anything away before building the basic structure in case I compromised the fuselage alignment. Normally I would be building this size model with 1.3 to 1.4 mm sticks with minimal sheet wood and be using a jig. The second half of this fuselage is built in the air so the first half needs to be accurate and stiff. Another reason for not spending too much time overthinking this model is that I want to complete it by the end of October. History has shown my build rate to be incredibly slow because I spend too much time thinking and not enough time doing.

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p40qmilj
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« Reply #4 on: September 18, 2019, 09:54:52 AM »

 Grin Paul if u want to save a pile of trouble, get rid of the plastic nose and make it out of balsa, in other words, extend the fuselage to the nose .  this will give u less need for ballast when u finish build .

next when you rebuild, blow plans up 130 %.  this size is a 21 inch span which is just right for these models

jim Grin ( been there done that!)
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dorme
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« Reply #5 on: September 18, 2019, 12:17:36 PM »

Guillows wood is like making Fiji Corn beef.  First throw away half of the can of corn beef.  Cook up some rice and vegetables.  Then throw away the rest of the corn beef and eat the rice and veggies.
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RolandD6
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« Reply #6 on: September 18, 2019, 06:01:32 PM »

Guillows wood is like making Fiji Corn beef.  First throw away half of the can of corn beef.  Cook up some rice and vegetables.  Then throw away the rest of the corn beef and eat the rice and veggies.

None of the kit wood is like any in my stash. The Guillows wood is heavy and has an indifferent grain, ie. goes all over the place and of unknown stiffness/strength for its weight. If I replaced it all then I would be scratch building and in that case I would begin with a much more lightweight design and use carefully selected wood. Then the model would not be finished before the end of October this year and I would not be able to participate in our scale model social event in December. The first Sunday in November being the last indoors opportunity for trimming, if it flies at all inside the space available.

The Pup may have been further advanced that what it is by now if it was not for the fact that I have been in and out of hospital four times since August 28th and I am still convalescing at home. If I miss having a model this year it will be yet another missed year. The model needs to fly for 20 seconds from a hand launch to qualify. It may turn out to be too heavy and fly too fast for the restricted space but at least I have participated.
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RolandD6
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« Reply #7 on: September 18, 2019, 06:18:40 PM »

Grin Paul if u want to save a pile of trouble, get rid of the plastic nose and make it out of balsa, in other words, extend the fuselage to the nose .  this will give u less need for ballast when u finish build .

next when you rebuild, blow plans up 130 %.  this size is a 21 inch span which is just right for these models

jim Grin ( been there done that!)

Thanks Jim. I was aware of the difficulties created by trying to use the plastic nose piece. I will be adding a balsa frame to the front of the kit frame and may or may not use parts of the plastic molding for expedience. I will be discarding the kit prop and nose button and substituting my own. I will be using a different two blade prop (Ikara or home made) and will be using an adjustable thrust button from my stock.

WW2 airplanes are not my favorite types anymore so I may not be building another. I will see how this one goes. I now prefer between wars American civil types more than anything else because the originals swung big props more suited to rubber powered models. The Bf-109 seemed a quick build possibility for our scale event and I could decorate it with non-Nazi markings, ie. Swiss markings.
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RolandD6
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« Reply #8 on: September 18, 2019, 08:36:32 PM »

Re: My comments about the wood grain.

Sheet B is the worst. The grain is very short in that it is mostly not parallel to the face of the sheet. Sheets A and C are better. The grain is reasonably parallel to the face but otherwise wanders.

I will be cutting my own strip wood because I don’t trust the kit wood. Only takes minutes with my balsa stripper.

Moving along.
I am double gluing with alphatic glue, ie. thin precoat allowed to penetrate followed by a very thin coat of full strength glue. Takes time because I am placing a maximum of two formers at a time, allowing the glue to dry between each placement. All seven are now in place and I have temporarily bridged the cockpit cutout so that I can lift the partial frame of the board. I will reduce the width of the side crutch before gluing it in place.
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TimWescott
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« Reply #9 on: September 18, 2019, 08:51:54 PM »

... I could decorate it with non-Nazi markings, ie. Swiss markings. ...

You could go full-on anti-nazi and build an Avia-199 -- https://en.wikipedia.org/wiki/Avia_S-199.  It lets you use a bigger prop and stay scale...
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RolandD6
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« Reply #10 on: September 20, 2019, 05:05:04 PM »

... I could decorate it with non-Nazi markings, ie. Swiss markings. ...

You could go full-on anti-nazi and build an Avia-199 -- https://en.wikipedia.org/wiki/Avia_S-199.  It lets you use a bigger prop and stay scale...

Yes I could. I will think about your suggestion.
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RolandD6
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« Reply #11 on: September 20, 2019, 05:24:05 PM »

A bit more progress.

I have inserted a splice at the tail end so that I could safely reduce the width of the vertical crutch members.

I have reduced the width of the side crutch to about 3 mm after trimming its outer shape the match the fuselage formers. I have left the crutch wider where it fits into the notched formers to get the correct alignment I may grind this off later but I will then need to add something to regain some side crush resisting strength.

The stringer extension of the side crutch at the tail is nominal 5.5 lb balsa, all to save a bit of weight. I will add at least one more side stringer before removing the frame from the building board and then remove more wood from the vertical crutch members and fuselage formers.

I have assembled the fin and rudder and commenced the tail plane. I WILL NOT BE USING THEM ON THE FINISHED MODEL. I will sand off about 1.5mm all around these items and use them as templates for laminated outlines.

I expect to be doing much the same for the wings which leads me too a question.

Should I build in a bit of wash-out into the wings. I know its is commonly accepted that one should do so for low wing models but does anyone know if it is a must for this model airplane?

In addition the plan says the dihedral should be 7/8" at each wing tip. Is this enough?

Paul

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Re: Guillows kit 505 Messerschmitt Bf-109
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ZK-AUD
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« Reply #12 on: September 21, 2019, 12:29:52 AM »

Washout gets my vote.  1/16 port and 3/32 starboard
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DHnut
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« Reply #13 on: September 21, 2019, 01:50:48 AM »

My McHard Me109E has 3/16" washin on the port wing and 1/8" washout on the starboard wing with a 1" dihedral on a 16" wingspan.
Ricky
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« Reply #14 on: September 21, 2019, 03:40:22 AM »

You do whatever is necessary to get 'em going and if Ricky says he needed washin then he did for sure, but differential washout would be a safer and more conventional starting point in a low wing model.  I believe this is how the great Czech modellers fly. 
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RolandD6
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« Reply #15 on: September 21, 2019, 05:47:51 AM »

Thank you for the advice fellas.

I will only get one shot at this and there are a few caveats.

1. I cannot use dope so doping and steaming is out.

2. I have developed techniques involving various acrylic materials that suit my asthma but a I cannot rely upon a drum tight covering to stiffen a wing.

3. Because of 2., I have a preference for Rees style wing structures that do not rely entirely on the covering for torsional strength.

A few years ago, Jim Fullarton built a DH71 Tiger Moth and Jim was a strong advocate of doping and steaming to induce washout etc. However Jim could not get the DH71 to fly. It would drop either wing IIRC. Jim modified the wings by installing ailerons and he got the model to fly. I was not privy to just how but it worked. I assumed he used the ailerons to simulate differential warping.

So what is the collective opinion about trying ailerons?

Did not get much done today because I did too much physical work yesterday, weeding the garden and vacuuming the house.

Paul
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DHnut
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« Reply #16 on: September 21, 2019, 03:43:55 PM »

 I have used ailerons instead of warps. The second Fike I build has separate ailerons and it was relatively easy to use port down aileron to raise the inside wing to stop a spiral in as the power ran down. My big Auster AOP 9 uses about 1/8" down aileron for the same reasons. The wing is very stiff in torsion so that is the only wayI can change the trim.  In some ways the use of ailerons is easier than warps that can change over time and the change is difficult to see. Have you used EZdope?
Ricky   
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« Reply #17 on: September 21, 2019, 04:24:07 PM »

I think it's important to keep the turn going the same way right through the flight, particularly indoor! Using aerodynamic trim to correct thrust line issues inevitably ends up being a compromise or a crash as the power runs out.  My own preference (while acknowledging that we all have our methods that work for us) is to make proper provision for easy thrust line adjustments and thereby avoid too much reliance on twisting wings or ailerons.  The washout question is more about preventing tip stalling in a less stable low wing subject.  It works.  Real ones have it.
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RolandD6
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« Reply #18 on: September 21, 2019, 07:38:51 PM »

I have used ailerons instead of warps. The second Fike I build has separate ailerons and it was relatively easy to use port down aileron to raise the inside wing to stop a spiral in as the power ran down. My big Auster AOP 9 uses about 1/8" down aileron for the same reasons. The wing is very stiff in torsion so that is the only way I can change the trim.  In some ways the use of ailerons is easier than warps that can change over time and the change is difficult to see. Have you used EZdope?
Ricky   

OK Ailerons it is with a bit more dihedral if the kit structure will allow it. I may be able to add a little bit of washout although my covering technique better suits a flat wing.

I have some EZdope, purchase shortly after I first noticed it mentioned in Aeromodeller magazine a few years back. At that time I did not know that it must be thinned out a lot so I got disappointing results (elephant skin).

I will be printing the tissue for this model so I will give EZdope a test run on a sample.
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RolandD6
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« Reply #19 on: September 21, 2019, 07:53:24 PM »

I think it's important to keep the turn going the same way right through the flight, particularly indoor! Using aerodynamic trim to correct thrust line issues inevitably ends up being a compromise or a crash as the power runs out.  My own preference (while acknowledging that we all have our methods that work for us) is to make proper provision for easy thrust line adjustments and thereby avoid too much reliance on twisting wings or ailerons.  The washout question is more about preventing tip stalling in a less stable low wing subject.  It works.  Real ones have it.

With the excepting of my reduced scale Hanger Rat (standard plane printed on A4 paper) and a distorted Baby Bipe,  I have the most success with left/left flight so I will stick with that if possible.

I will be using one of my home made adjustable thrust buttons that use three 2-56 nylon grub screws. With the right sized bearing tube and teflon bearings it is possible to get at least 3o degrees angle in any direction. I can also preset a bit of offset in the nose block.

Not seen a real Bf 109 close up but I have looked carefully along the wing of a real Spitfire Mk VIII which does have noticeable washout. Also looked at the wing of a HS 748. It may it may not have washout (too high in the air for me to see properly) but it is quite clear that the wing section changes from root to tip. The section camber line may or may not change along the wing but the wing tip lower surface has very noticeable under camber, whereas the root section (using a silly aeromodelling term) is 'semi-symmetrical'.
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Don McLellan
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« Reply #20 on: September 22, 2019, 01:00:06 AM »

Hi Paul,

Further to not being able to use dope to paint and finish tissue, what about printing tissue?  If you have an Epson printer with Durabrit ink, it is bullet proof when it comes to shrinking with water and alcohol.  Then if you want to seal the tissue with clear dope maybe a friend could spray it for you.  Just a thought.

Cheers,

Don
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DHnut
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« Reply #21 on: September 22, 2019, 01:47:45 AM »

The note with the McHard plan state that a left /left trim is the preferred one and what I have used with my low winged models. The wash out holds the inner wing up in the tern and on a number of occasions when I have added a gurney strip the flight has been tranformed as the lift vector becomes more vertical.
look forward to seeing the finished model.
Ricky
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RolandD6
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« Reply #22 on: September 22, 2019, 02:31:27 AM »

Hi Paul,

Further to not being able to use dope to paint and finish tissue, what about printing tissue?  If you have an Epson printer with Durabrit ink, it is bullet proof when it comes to shrinking with water and alcohol.  Then if you want to seal the tissue with clear dope maybe a friend could spray it for you.  Just a thought.

Cheers,

Don

Hi Don

Thank you for the suggestion. I do have an Epson printer that uses Durabrite ink and I am planning to print the tissue at this stage. The wings of the Sopwith Pup are covered with printed 6 gsm Tengujo tissue which needs to be sealed before printing. I sealed the tissue with a white acrylic ink concoction by laying the tissue on a sheet of polypropylene plastic (low surface energy) and brushed the ink onto the tissue. I lifted the tissue when dry and tacked it to an A4 sheet of bond paper and ran it through the printer. The tissue was then put on to the wing frame dry. I may decide to give it a light dusting of clear acrylic ink (ie. no dye or pigment) before assembling the model.

Since then I have found a sheet of very thin clear silicon rubber and quick tests have suggested it will work better than the polypropylene. I found the polypropylene could only be used once. Even though it has low adhesion properties when the surface is fresh, coating it with acrylic ink or paint changes that property so the ink or paint will stick next time around. Cleaning the polypropylene with alcohol, Windex or any other of the usual materials that will remove the acrylic did not restore the non-stick properties sufficiently.

I have some 9 gsm Silkspan, some 9 gsm unbuffered art tissue, some 9 gsm Sagigawa tissue normally used for block printing by artists and some 10 gsm ‘domestic’ tissue. All of these have fewer holes when compared to the Tengujo so they may be be printable without further preparation and the finished weight may be about the same as the Pup’s Tengujo covering. I have yet to examine them more closely and decide.

I will only go down the doping path if other more health friendly methods fail because I do not want to be dependant on other people but thank you for the suggestion.

Paul
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RolandD6
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« Reply #23 on: September 22, 2019, 02:40:30 AM »

The note with the McHard plan state that a left /left trim is the preferred one and what I have used with my low winged models. The wash out holds the inner wing up in the tern and on a number of occasions when I have added a gurney strip the flight has been tranformed as the lift vector becomes more vertical.
look forward to seeing the finished model.
Ricky


Wash out on the inner wing tip? I would have thought the opposite.

I have had success with Gurney strips on the inner wing of a turn but too much Gurney flap will cause the model to straighten out and even turn right because the lift overcomes the drag effect. There needs to be a balance between lift and drag on the inner wing tip. The Hanger Rat I mentioned earlier needs weight on the right tip and it needs to be hand launched with a right bank. Not enough initial bank will cause it to fly straight until it hits the far wall.

Paul
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« Reply #24 on: September 22, 2019, 02:50:58 AM »

Apologies it was ment to be washin.
Ricky
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