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        Build Log Frog Tomtit 200%

#1 colibriguitars Nov 20, 2012 12:08 AM

Frog Tomtit 200%
 
3 Attachment(s)
Hi everybody!!
after learning and flying two small models, and listening to the suggestions about a bigger plane flies easily, a FRIEND of mine send me the magazine with the Tomtit 2X plans. i will build slow, because its is the biggest plane i have ever build. here some pictures.
Thanks for watch!

#2 colibriguitars Nov 20, 2012 01:02 AM

Hi Guys! Watching the plans, i noticed no downtrust or ridetrust, What you think?

#3 Gluehand Nov 20, 2012 02:31 AM

Hi,
I would add 1.5 - 2 right for a start, beeing prepared for further fine-tweaking...

If the mean decalage (bipe) is more than a degree or so, I would also dare to add some downthrust as well, initially....

No rocket science...:p...but this is basically how I would "think" with a build like this....

:)

#4 kkphantom Nov 20, 2012 02:56 AM

Sundancer will know, it's his design!

#5 Sundancer Nov 20, 2012 03:09 AM

That isn't so slow Rodrigo!

As this is my design, I feel I should comment on the thrustline question:

The plan shows no down or side thrust and that is the way my prototype is set up, I am quite happy with the way it flies. At full throttle it has a natural climb angle of about 20-25 degrees with the 140 watt motor I am using (8 x 4.3 prop). To cruise level, reduce throttle to about half. I can detect no need for side thrust.

If you wish, you could add 2 to 3 degrees of downthrust; this would just mean that the model would fly level at a higher throttle opening, but faster! My view of these free-flight-to-radio conversions is that they SHOULD naturally climb at full throttle, as the free-flight model would, you use the PROPORTIONAL throttle control to achieve the flight status you want - climbing, level or descending, just as you would with a full size aircraft - but if you prefer a more "radio" trim, then you can add the downthrust. However, be aware this is NOT intended to be an aerobatic model which will hurtle around level at full throttle - you could make it do that by thrustline, incidence and CG changes but it would lose much of it's charm to me. With regard to right thrust, I don't think the model needs it, there is no noticeable deviation between part and full throttle on mine. Again, if you wish, add a couple of degrees right thrust, I don't think it will make much difference one way or the other.

Perhaps the best thing to do would be to build it as per plan, but leave off the front cowling for now. Fly it, adjust the thrustline if you feel the need and then make and fit the cowling.

#6 colibriguitars Nov 21, 2012 10:28 PM

7 Attachment(s)
today, after fixing my FROG Redwing, now i can focus in my next project. Working on battery hatch, planked and ready to fit and tons of sand!

#7 colibriguitars Nov 22, 2012 12:58 AM

Hi George! soon i will start to build the wings, and i have a question, to bend the balsa with ammonia, just ammonia or mixed with water?
Thanks a lot!

#8 Sundancer Nov 22, 2012 02:39 AM

I used only water, soaking the strips for an hour or so, but I did have some very good balsa. Perhaps it would be better to use a mixture of ammonia and water in case your balsa is not quite so good. Leave them to soak, then just wipe them with tissue and pin up the laminations without glue. Leave them 24 hours to dry out, then unpin (you will find the bend will stay in the wood), glue and replace. I use PVA or aliphatic resin for gluing the laminations up, it needs to be a glue that will sand well.

You are making good progress - you definitely are not a slow builder!

#9 kkphantom Nov 22, 2012 02:47 AM

When doing laminated tips I've always used 1/32"strips and found that ammonia is rarely necessary at all.

#10 Sundancer Nov 22, 2012 03:20 AM

KK is right about 1/32" Rodrigo, if you have some 1/32" sheet I would use double the number of laminations (6) of this rather than the 1/16". The reason 1/16" is shown on the plan, and used in my original model, is that I didn't have any 1/32" at the time and as I have to order all my balsa in batches for delivery from the UK I didn't want to wait.

#11 Colonel Blink Nov 22, 2012 06:56 AM

Nice work there, cg!!

#12 colibriguitars Nov 22, 2012 11:49 PM

Hi Guys, no pictures today, im working on the second hatch, buy im worry about weight, the fuselage on the photos stage with part of the second hatch, is 84g. and all the bottom sheets are missing, also servo mounts and brass tubes for landing gear!
tomorrow i have to find some material for templates for start bending the tips for wings and rudder and elevator.

#13 Sundancer Nov 23, 2012 01:49 AM

Don't be too worried about weight CG, remember this is a much bigger model than you are used to. Mine weighs 450 grams all up, anything upto 600 grams or even a bit more will be fine, there is a lot of wing area there.

#14 Colonel Blink Nov 23, 2012 02:01 AM

George, which mag & issue was this plan included in? It's a lovely looking model, and I may want to have a go myself someday....:D Must be a good feeling to have someone building your design...

I've always liked biplanes; before the announcement of the Britplan build off I was contemplating suggesting a 'multi-' build off - ie multiple wings, multiple motors, multiple fuselages (well, twin-boom anyway)....

#15 Sundancer Nov 23, 2012 03:43 AM

It is nice when people want to build a design you have created Colonel - but it can also be a mixed blessing sometimes as you have no control over the skill level of the builder! No problem in this case as CG is so obviously a great craftsman and a better builder than I am, but back in the UK I sold a couple of thousand copies of the various Sunfly designs, and although the vast majority of builders had no problems, there were one or two which resulted in very protracted correspondence and caused some hair tearing moments!

The Tom Tit plan and article was in the July edition of Quiet and Electric Flight International. The second of my Frog scale-ups, the Mamba is receiving the same treatment in the December issue, out next week, and the Sportster and Mercury Mars are scheduled for some time in the new year.


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