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Old Feb 26, 2010, 10:57 AM
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Sussex, UK
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Incidences

I am just about ready to glue the boom to the fuselage pod, the boom that I acquired tapers from 22mm to 18mm, so I had to modify the hole in F5 in order to put it in the right position and look correct where it exits the rear end of the fuselage pod.
Looking at the plans and the magazine article it would appear that the wing and the tailplane are at 0 degrees incidence. Is this correct? (I noted the use of the 55mm dimension )

BTW thanks for the weight figures you supplied me, I looked in the box before hand but Traplet appears to have replaced your box with another and do not mention it.

I have made all the wings and am about to shape the trailing edges, some of which are quite small, I should probably have partially removed some of the 3/16 sheet at the trailing edges before glueing.
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Old Feb 26, 2010, 12:01 PM
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Originally Posted by #cherokee View Post
I am just about ready to glue the boom to the fuselage pod, the boom that I acquired tapers from 22mm to 18mm, so I had to modify the hole in F5 in order to put it in the right position and look correct where it exits the rear end of the fuselage pod.
Looking at the plans and the magazine article it would appear that the wing and the tailplane are at 0 degrees incidence. Is this correct? (I noted the use of the 55mm dimension )

BTW thanks for the weight figures you supplied me, I looked in the box before hand but Traplet appears to have replaced your box with another and do not mention it.

I have made all the wings and am about to shape the trailing edges, some of which are quite small, I should probably have partially removed some of the 3/16 sheet at the trailing edges before glueing.
I think you may be getting confused, as do a lot of people, in when viewing the incidence angle, you are taking the bottom of the wing on the fuselage, as the datum.
The incidence angle is taken from a line drawn through the centre of the LE radius thence to the point of the rear of the TE. This should give an angle of 1.5 degrees. This should be set to the bottom of fiuselage, if cut correctly, which we will assume being laser cut, it is, which is flat, so as to set it up correctly
The 55mm is a guide as any variance from what I had, can cause a difference i.e if the pylon for the tailplane is slightly higher or lower etc. Important thing is to make sure it is parallel to the fuselage bottom when on the board & the fin when viewed above is central to the plan or a centre line drawn on building board, to line up fuselage pod.

Shaping the TE can be daunting, but in my view is best done after building the structure, but do make sure that you glue the 1/16" sheet pieces between the ribs, to support them, or it will all come apart as they have no support without them, while you shape it

The best way is to use a piece of say MDF, or a board of some sort. Lay the wing panel on it so as the TE is say 1/16" in from the edge. Then using a razor plane, plane the material away as close as you feel comfortable doing, then finish with a sanding block.
The reason for having it inset from the edge is so as to stop you from planing & sanding it to thin at the back, or even going right through it.
You could practice on a bit of scrap 3/16" sheet beforehand.
Where the ribs are inset between the 1/16" support pieces, gives a guide as to how close you are getting to the ribs whilst shaping the TE.
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Old Feb 26, 2010, 01:41 PM
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Thanks for your reply, I shouldn't have used the word incidence what I meant was that the bottom of the fuselage, the top face of the tailplane mount, and the top face of the wing mount all appear to be parallel to each other.
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Old Mar 03, 2010, 06:30 AM
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Metric Aluminium Tubing

Metric Aluminium Tubing can be bought at -

www.gliders.uk.com - 1m lengths (cheaper, but postage costs more)

www.cornwallmodelboats.co.uk - 300mm (12") lengths (cheaper postage)

BTW Brian, if my maths is correct, I calculate the wing loading for the 100" model as 7oz per sq ft - 42 grams weight divided by wing area of approx 864 sq inches (6 sq ft) = 7.
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Old Mar 03, 2010, 07:46 AM
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My apologies if this has been answered already, but may I ask, if I buy the Traplet plans plus their wood set, is it relatively easy to build the larger wingspan version? Thanks.
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Old Mar 03, 2010, 11:50 AM
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Quote:
Originally Posted by Thermal Rider View Post
Metric Aluminium Tubing can be bought at -

www.gliders.uk.com - 1m lengths (cheaper, but postage costs more)

www.cornwallmodelboats.co.uk - 300mm (12") lengths (cheaper postage)

BTW Brian, if my maths is correct, I calculate the wing loading for the 100" model as 7oz per sq ft - 42 grams weight divided by wing area of approx 864 sq inches (6 sq ft) = 7.
Think that should read ounces for the 42 grams weight, if only I could build that light

The wing area I think should be a bit less than 864 sq inches, with the centre panel at 10 X 36 = 360, inner tips at MC at 9 X 20 =180 X 2 = 360 & tip panels at MC 6 X 10 = 60 X 2 = 120 so we have 360 + 360 + 120 = 840 plus a bit for the tip blocks at say 7sq inches makes 847 sq inches approx.

The 3.1 metre wing is about 1027 sq inches, giving a loading of approx 6.36 onces for the 7.13 sq inches of wing area.

Keep the feedback going on sorces of supply as it all helps in the long run.
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Old Mar 03, 2010, 11:58 AM
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Originally Posted by cvanscho View Post
My apologies if this has been answered already, but may I ask, if I buy the Traplet plans plus their wood set, is it relatively easy to build the larger wingspan version? Thanks.
If you only intend to build the 3.1 metre version, the tip ribs as supplied in the wood pack will need to be spaced further apart to fit the taper. I can supply you with the sections for the larger wing tips, if you PM me.
You will also have to draw out the larger tip panels so as you can build them. This is not difficult as the LE is straight so you can draw them out, using the chords as shown on the plan with the inner tip panels at 26 inches long & the tip panels at 16 inches span.
Doing this keeps the rib spacing at 2 inches, as on the 100 S version.

I would advise build the standard version then build the larger tips at a later date.
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Old Mar 03, 2010, 12:51 PM
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Thanks!
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Old Mar 03, 2010, 10:00 PM
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Originally Posted by Essex BOF View Post
Think that should read ounces for the 42 grams weight, if only I could build that light

The wing area I think should be a bit less than 864 sq inches, with the centre panel at 10 X 36 = 360, inner tips at MC at 9 X 20 =180 X 2 = 360 & tip panels at MC 6 X 10 = 60 X 2 = 120 so we have 360 + 360 + 120 = 840 plus a bit for the tip blocks at say 7sq inches makes 847 sq inches approx.

The 3.1 metre wing is about 1027 sq inches, giving a loading of approx 6.36 onces for the 7.13 sq inches of wing area.

Keep the feedback going on sorces of supply as it all helps in the long run.
I was going to correct myself, but you beat me to it. However, I don't think your 7.13 sq inches of wing area would support a glider of 3.1 metres. It shows we are only human, doesn't it.

On the plan, I measure the wing tip panels as 12 inches plus the actual tips, hence my figure of approx 864 sq inches. Am I missing something?
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Last edited by Thermal Rider; Mar 03, 2010 at 10:09 PM. Reason: Forgot to mention
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Old Mar 04, 2010, 04:13 AM
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Originally Posted by Thermal Rider View Post
I was going to correct myself, but you beat me to it. However, I don't think your 7.13 sq inches of wing area would support a glider of 3.1 metres. It shows we are only human, doesn't it.

On the plan, I measure the wing tip panels as 12 inches plus the actual tips, hence my figure of approx 864 sq inches. Am I missing something?
Touche as they say funny how when you check something you miss the basic things, plus you are right in that the tips are 12 inches plus the tip
So will bow to you having checked it out more than I have done since I built it.

Many thanks for pointing it out, as I would probably have gone on quoting it at 10 inches. it makes the span 102" or 2.59 metres flat

As my old foreman used to say "the person who never made a mistake, has never made ---- all"
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Old Mar 04, 2010, 05:31 AM
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Originally Posted by Essex BOF View Post
Touche as they say funny how when you check something you miss the basic things, plus you are right in that the tips are 12 inches plus the tip
So will bow to you having checked it out more than I have done since I built it.

Many thanks for pointing it out, as I would probably have gone on quoting it at 10 inches. it makes the span 102" or 2.59 metres flat

As my old foreman used to say "the person who never made a mistake, has never made ---- all"
You are right, the span is approx 102" (36"+ (2x20") + (2x12") + wing tips).

On a different aspect (no pun intended), do you have any suggestions as to using the SD7037 airfoil. The MH32 is a fast airfoil (originally used in pylon racing), whereas the SD7037 is thicker, therefore slower and I am thinking that I might prefer this. On the other hand, would the SD7037 have enough penetration for anything other than a windless day with this weight and size of glider?
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Old Mar 04, 2010, 09:35 AM
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Originally Posted by Thermal Rider View Post
On a different aspect (no pun intended), do you have any suggestions as to using the SD7037 airfoil. The MH32 is a fast airfoil (originally used in pylon racing), whereas the SD7037 is thicker, therefore slower and I am thinking that I might prefer this. On the other hand, would the SD7037 have enough penetration for anything other than a windless day with this weight and size of glider?
Nothing wrong with SD7037, but you will need to alter the wing seat to get the right incidence on the wing, i think as it has more camber.

I used to use SD7035 on my gliders, but found MH32 was a better all round section. 7037 will probably hang better. That said try it out it might be better.
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Old Mar 10, 2010, 03:28 AM
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Control Throws?

I have looked and not seen any indications of control throws, does anyone have any guidance please.
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Old Mar 11, 2010, 02:48 AM
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I have looked and not seen any indications of control throws, does anyone have any guidance please.
Rudder as much as you can get, although you will not need it all. Elevator approx 30 degrees up/down & set the rates to 50%, so as you can get a feel for the model in the air. Control rate are subjective to the flyer & what he is comfortable with. The settings below are a GUIDE & not written in sand, but are the ones as used on my original off the TX.

You will need to program in some DOWN elevator with the power on, I use 12% down for the power phase.

When spoiler is deployed, the elevator has 26% UP elevator to cover the pitching down effect of the spoiler.

The spoiler blade should deploy to approx 75-80 degrees, adjust to suit.

If you have not flown this type of model before, the motor should NOT be used at full power until you are used to it & or set the amount of down elevator to compensate for the model trying to loop under full power due to the high climbing speed over it's normal flying speed.

Applying full spoiler produces an opposite to the power phase in that the model will pitch DOWN, if you apply full spoiler with no UP elevator to compensate.
If you were to fit flaps, instead of a spoiler, then the elevator compensation on applying full DOWN flap, would be to opposite to a spoiler, in regards to using DOWN elevator to compensate for the flaps.

Hope this may be of help, as it is a bit difficult to describe
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Old Mar 21, 2010, 05:43 PM
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Sussex, UK
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Prop Size

I was testing the electrics on my 2500 Watts Up today.

I am using a 300 watt BRC inrunner driving a 4.4:1 maxon copy gearbox, 11.1 volts, 2700kV, I had fitted the largest prop I had available a 13 x 5 aeronaut , target weight of complete model is 1200g.

Wattmeter showed 169 watts and 16 amps.

Which prop should I change to a 14 x 9/10 or maybe a 15 x 10 ?
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