Afternoon all,
So I am getting back into building free flight balsa kits but wanted some tips. I have built a fair few models with good success, that is until I go to fly them. I think I understand the methods to get the CG but struggling with trimming. what methods are there and what would be the best? I am currently building a Guillows 403 Spitfire and have already seen a next project (Dumas MIG 17). I've heard of a method by using a drinks can piece as a hinge and then fixing this in place. is this correct?
one last thing, what glue is the best choice. I'm usually using a medium CA.
kindest regards
Andrew
Free Flight trimming
Re: Free Flight trimming
Hi Andrew, and welcome to Small flying Arts!
You may find that it will likely take a few days to get answers, as the Forum is not yet fully active/announced and is still in the 'set-up' phase, but we're getting there!
To start with your questions, building as light as possible is one of the prime goals for successful Free Flight which entails careful wood selection, using glues intelligently (there are many different types that we can use) and using only enough to get the job done (VERY little). Guillow's models are very nice but are 'commercial' and thus subject to mass production rules - using wood available (not always the best/lightest) and generic plastic parts that may or ma not really fit the subject. They HAVE improved over the past couple of years with laser cutting and better wood selection, thanks to modelers who are acting as consultants, but the kits are designed to be multi-purpose (rubber/fuel/electric FF/rc/CL) in one box - this demands compromise = added weight.
Lightening a stock kit usually means removing as much material from the sheet formers as possible without ruining the structural strength - hogging out the center to within approx. 1/4 inch of the stringer notches, wing-tip parts can be narrowed and the trailing edges of the wings can be 'holed'.
Glues: CA glue is great, but inherently HEAVY - what goes on is what you'll end up with, like epoxy - and is nearly impossible to sand once cured, especially on S&T models. It does have its place when instant grab is needed in an area where sanding won't be an issue and is applied with a pin type applicator (one TINY drop). CA also has a penchant for getting on the wrong part or wicking thru wood, attaching itself to the wrong spot (usually the fingers). Using MEDIUM helps, but the joint can end up heavier than the same join with the thin stuff. I use CA on occasion, but my glue of choice is UHU Hart, thinned 50-50 with acetone. Alternatives are DUCO, Testor's Balsa cement, Ambroid (if you can find it and are not put off by the dark amber color) - also thinned. There are a few others that have been "discovered" recently and are still being evaluated, but I can't comment on them as they are unavailable to me.
I' not that familiar with the 403 Spitty, but I DO know that it is a viable flyer. The size is in it's favor and if there is the necessary decalage (the incidence difference) of ~ 3°, it should fly. The plan should show a suggested balance point for each power system. Test glide as suggested on the plan over the tallest grass you can find and on a calm day (hopefully). I would not recommend hinged surfaces, as they WILL get bumped out of kilter immediately after you find the optimum setting and adds weight back where you definitely don't want it. Some have done so with great success, but they usually end up gluing the surfaces solid. Make the stab slot/mount so that you can adjust the complete stab with shims, gluing it solid once the sweet spot is determined.
More later.. and post some photos!
Pete
You may find that it will likely take a few days to get answers, as the Forum is not yet fully active/announced and is still in the 'set-up' phase, but we're getting there!
To start with your questions, building as light as possible is one of the prime goals for successful Free Flight which entails careful wood selection, using glues intelligently (there are many different types that we can use) and using only enough to get the job done (VERY little). Guillow's models are very nice but are 'commercial' and thus subject to mass production rules - using wood available (not always the best/lightest) and generic plastic parts that may or ma not really fit the subject. They HAVE improved over the past couple of years with laser cutting and better wood selection, thanks to modelers who are acting as consultants, but the kits are designed to be multi-purpose (rubber/fuel/electric FF/rc/CL) in one box - this demands compromise = added weight.
Lightening a stock kit usually means removing as much material from the sheet formers as possible without ruining the structural strength - hogging out the center to within approx. 1/4 inch of the stringer notches, wing-tip parts can be narrowed and the trailing edges of the wings can be 'holed'.
Glues: CA glue is great, but inherently HEAVY - what goes on is what you'll end up with, like epoxy - and is nearly impossible to sand once cured, especially on S&T models. It does have its place when instant grab is needed in an area where sanding won't be an issue and is applied with a pin type applicator (one TINY drop). CA also has a penchant for getting on the wrong part or wicking thru wood, attaching itself to the wrong spot (usually the fingers). Using MEDIUM helps, but the joint can end up heavier than the same join with the thin stuff. I use CA on occasion, but my glue of choice is UHU Hart, thinned 50-50 with acetone. Alternatives are DUCO, Testor's Balsa cement, Ambroid (if you can find it and are not put off by the dark amber color) - also thinned. There are a few others that have been "discovered" recently and are still being evaluated, but I can't comment on them as they are unavailable to me.
I' not that familiar with the 403 Spitty, but I DO know that it is a viable flyer. The size is in it's favor and if there is the necessary decalage (the incidence difference) of ~ 3°, it should fly. The plan should show a suggested balance point for each power system. Test glide as suggested on the plan over the tallest grass you can find and on a calm day (hopefully). I would not recommend hinged surfaces, as they WILL get bumped out of kilter immediately after you find the optimum setting and adds weight back where you definitely don't want it. Some have done so with great success, but they usually end up gluing the surfaces solid. Make the stab slot/mount so that you can adjust the complete stab with shims, gluing it solid once the sweet spot is determined.
More later.. and post some photos!
Pete
Comparing Spammers to a pile of organic waste is an insult to the organic waste!
-
andrewpjudge
- Posts: 6
- Joined: Wed Oct 12, 2016 12:46 pm
Re: Free Flight trimming
Pete thank you so much for all the useful information you gave me. I will definitely look at trying a new glue such as UHU Hart. I will look into methods to lighten the aircraft when I get around to building.
Out of curiosity what kits or companies would you recommend? Dumas, west wings? Or would these all equally suffer from mass production draw backs.
Kindest regards
Out of curiosity what kits or companies would you recommend? Dumas, west wings? Or would these all equally suffer from mass production draw backs.
Kindest regards
Re: Free Flight trimming
West Wings kits are VERY nice with generally good wood, but are a bit over-designed which adds weight. They are fairly accurate and VERY well executed (scale kits). I've got the Spitfire Mk 22/24 framed up plus 2x Sea Fury, Hawker 'Hart' and the Do 235. They are OK without having to modify - but always check wood quality and replace if needed.
I've not built any DUMAS kits and only have one in my stash (Walnut size) form an OLD run (late 80's is my guess), but I've seen some of the larger models in the bones state which seemed nice (again a bit over-built), so I can't give any good advice here.
Good kits with good to great wood/accessories can be found at Diels Engineering, GAR (Golden Age Reproductions), and Easy Built Models (click on the names). There are other, but I'll have to check if the links are still active.
Once we get the site here fully activated and announced, you'll be inundated with more info than you can probably assimilate
!
I've not built any DUMAS kits and only have one in my stash (Walnut size) form an OLD run (late 80's is my guess), but I've seen some of the larger models in the bones state which seemed nice (again a bit over-built), so I can't give any good advice here.
Good kits with good to great wood/accessories can be found at Diels Engineering, GAR (Golden Age Reproductions), and Easy Built Models (click on the names). There are other, but I'll have to check if the links are still active.
Once we get the site here fully activated and announced, you'll be inundated with more info than you can probably assimilate
!Comparing Spammers to a pile of organic waste is an insult to the organic waste!
-
andrewpjudge
- Posts: 6
- Joined: Wed Oct 12, 2016 12:46 pm
Re: Free Flight trimming
I look forward to the site being fully activated and gaining more knowledge. One quick question, with regards to gluing acetone is nail varnish remover is this good for a thinner or would i need a pure acetone with no color etc. I've recently heard of a 'double gluing' method too which i may try by applying small amounts with a brush and so on
Re: Free Flight trimming
Try PVA as an adhesive.
Re: Free Flight trimming
Uhu Hart for sure. 50% diluted and in 2 steps: apply, assemble, disassemble, let dry, apply again, assemble and fix assembled parts on board with pins etc. Never fails. If necessary, disassemble with acetone. I seldom use ca for the reasons Pete already mentionned. For applying tissue uhu glue stick (and saliva) is a good option, but there are many other options. Check this link for a good trimming guide: http://www.gryffinaero.com/models/ffpag ... 0step.html
regards, Ludo (Uhu)
regards, Ludo (Uhu)