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Old Dec 19, 2009, 05:45 AM
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2 Metre Version

I had intended to do a 2 Metre Version of the model, but time & other things have got in the way.
But having looked at the design I see that if another set of Inner Wing Tip panels were built, with the tip blocks added to them, the model would qualify for the 2 Metre class, with little modification, giving a truly all round model.
The span ending up at the 78 inches to qualify.
The only mod that I was going to do was to increase the taper on the tips to look a bit more appealing.
Has anybody else picked this up or are intending to build a 2 Metre Version?
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Old Dec 22, 2009, 07:47 AM
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Sao Paulo - SP
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Hi Fen

Thanks for share. Could you please detail those rudder and spoiler servos?

Thanks

JC
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Old Dec 24, 2009, 02:39 AM
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Originally Posted by JC Fardo View Post
Hi Fen

Thanks for share. Could you please detail those rudder and spoiler servos?

Thanks

JC
Try the SD100 servo for the rudder/elevator, as I have used them & found them very good & being 9mm deep fit in easily.
For the spoiler, I have found that the Hyperion DS09 looks to be the best bet as it has 140 degrees total travel, which will be of use in getting as much throw on the blade as it is possible to obtain.

You can of course use these on the rudder/elevator & they do a metal gear version as well.

Avoid Graupner 1081's as I used them originally, but the gear train is very weak & strips easily.
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Old Dec 29, 2009, 02:17 PM
Richard
Staffordshire
Joined Dec 2009
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Back after a long time away

Having just returned to the aero modelling scene after an absence of 35 years Santa has brought me the wood pack plan and a few other bits and bobs. From an engineering aerospace back ground the build should hopefully not be too much of a problem. What I really need help with is the motor,ESC ,battery pack/s and prop size and pitch. Having just gone down to my local model shop both the owner and I nearly fell through the floor when the price he gave me for the AXI C/W gearbox was nearly 150. I note from the artical that both boxed and unboxed motors can be used, what are the pros and cons of these two options? If using an unboxed motor any suggestions as to what to go for and which size of ESC and prop to use?

Regards

Richard.
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Old Dec 30, 2009, 03:37 AM
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The article does state a Mega22/20/3E, which cost approx 65 now, as an alternative to the Multiplex used on the prototype. That is no longer available in the UK but can still be sourced from Northeast Sailplanes in the US

ESC can be sourced from Giant Cod, to suit at reasonable cost or BRC Hobbies, if you are unsure as to what you need use a 50-60 amp one so as to cover pushing to much power through a smaller one.
This is where a watt meter comes into play as you can checkout various prop setups, by borrowing from other flyers, to check out.

Prop combinations are harder to specify, a 10X6 folder would be a good start for the Mega or the motor in the link above.
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Old Dec 30, 2009, 01:37 PM
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If you wanted to build the 2m version would all other dimensions stay the same (fuse/boom length, Tailplane/Fin etc) or would they have to be reduced proportionally?
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Old Dec 31, 2009, 03:43 AM
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Originally Posted by Quadra21 View Post
What I really need help with is the motor,ESC ,battery pack/s and prop size and pitch. Having just gone down to my local model shop both the owner and I nearly fell through the floor when the price he gave me for the AXI C/W gearbox was nearly 150. I note from the artical that both boxed and unboxed motors can be used, what are the pros and cons of these two options? If using an unboxed motor any suggestions as to what to go for and which size of ESC and prop to use?

Regards

Richard.

Further to my previous reply, the problem is that when you need to use a gearbox, the price on a motor jumps considerably due to the cost of the Gb being 40-50 on it's own.
Prefer innrunners as there are no wire's to get in the way. On the out runners the wire have to clear the revolving case, which is difficult in a confined area of the nose. Mounting the motor the other way round with the wires to the rear, means adding a former behind the nose former. Not an easy or practical job.
An inbetween solution would be to use the following link which is an outrunner with gearbox, which a lot of flyers are using now, of the Hacker A20 with a gearbox, wich retail for 93 from West London Models

http://www.westlondonmodels.com/prod...20-6XL-Geared/

Even the Mega has gone up from what I quoted, no doubht due to the fall against the Euro.

A boxed motor will allow props of 14-16 dia or bigger, where as direct drive will only drive the smaller size's, which is not much use for gliders/sailplanes.
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Old Dec 31, 2009, 03:50 AM
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Originally Posted by RSTMG View Post
If you wanted to build the 2m version would all other dimensions stay the same (fuse/boom length, Tailplane/Fin etc) or would they have to be reduced proportionally?
That is what I intended to do so as just the tips were changed to fly in both classes.
You could make the tailplane slightly smaller, but do not think that it would make much difference.
There would be an increase in % tail area, which would allow the CG to go back & Mean Wing Chord would increase, but being able to move the battery back should cover this.
Try it would like to know
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Old Jan 01, 2010, 09:33 AM
Richard
Staffordshire
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Essex BOF. Happy New Year. Many thanks for the info, it's nice to see there are still some helpful people out there.

Regards

Richard.
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Old Jan 02, 2010, 05:44 AM
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Originally Posted by Quadra21 View Post
Having just returned to the aero modelling scene after an absence of 35 years Santa has brought me the wood pack plan and a few other bits and bobs. From an engineering aerospace back ground the build should hopefully not be too much of a problem. What I really need help with is the motor,ESC ,battery pack/s and prop size and pitch. Having just gone down to my local model shop both the owner and I nearly fell through the floor when the price he gave me for the AXI C/W gearbox was nearly 150. I note from the artical that both boxed and unboxed motors can be used, what are the pros and cons of these two options? If using an unboxed motor any suggestions as to what to go for and which size of ESC and prop to use?

Regards

Richard.
As an aid to help sort out what would be the best setup for any model, I discovered this site some time ago that is simple to use & seems to give a good base to work too.

http://brantuas.com/ezcalc/dma1.asp

Just pick the nearest item to what you want to use, then get the result . What you need to bare in mind is THRUST, which this system gives at the end . So alter things around like props,battery's(2or3 cell, this will give a difference in power as the revs will drop if you go to a 2 cell, as the Kv will reduce with the Volts of motor, but amps will go up so make sure the ESC is capable of the additional amps when using the lower voltage)

Base what you need on the weight of model using 90-100 watts per pound as a basis of good performance.

I have found this easier to use than Motorcalc, that a lot of people swear by, but it is a free b.
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Old Jan 02, 2010, 10:32 AM
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I have been sent an E mail with this link below, as an alternative to the one mentioned in the previous reply. It is a free programme & updates regularly, so that would be a bonus

http://drivecalc.de/

Thanks to Spencer Greenhalgh for this update
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Old Jan 03, 2010, 06:04 AM
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Originally Posted by Essex BOF View Post
The article does state a Mega22/20/3E, which cost approx 65 now, as an alternative to the Multiplex used on the prototype. That is no longer available in the UK but can still be sourced from Northeast Sailplanes in the US

ESC can be sourced from Giant Cod, to suit at reasonable cost or BRC Hobbies, if you are unsure as to what you need use a 50-60 amp one so as to cover pushing to much power through a smaller one.
This is where a watt meter comes into play as you can checkout various prop setups, by borrowing from other flyers, to check out.

Prop combinations are harder to specify, a 10X6 folder would be a good start for the Mega or the motor in the link above.
Hi Essex BOF,

A very happy New Year!

When the above post was first made, you made reference to a Turnigy motor from HK. Unfortunately I was in the US when you first posted the message and was going to follow it up on my return as I still have to procure my drive train. Any chance of repeating that link please as I am not quite sure which motor to use? Many thanks!
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Old Jan 03, 2010, 07:37 AM
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Hi Essex BOF,

A very happy New Year!

When the above post was first made, you made reference to a Turnigy motor from HK. Unfortunately I was in the US when you first posted the message and was going to follow it up on my return as I still have to procure my drive train. Any chance of repeating that link please as I am not quite sure which motor to use? Many thanks!
The link I quoted was not really suitable as it was to fast plus the shaft was 4mm so you could not fit a gearbox. This was the link:-

http://www.hobbyking.com/hobbyking/s...mpeller_2600kv

A better bet would be this one but check it out first, it has 5 mm shaft which is good & the Kv is 810 per volt, but only runs on 3-4 cells, so you could not put a 2 cell li po on it:-

http://www.hobbyking.com/hobbyking/s...idProduct=9449

With all of these in runners the case is 36 mm dia so room is limited in the front as it would be on the Mega, but price at $26
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Old Jan 08, 2010, 04:42 AM
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Originally Posted by Essex BOF View Post
....
A better bet would be this one but check it out first, it has 5 mm shaft which is good & the Kv is 810 per volt, but only runs on 3-4 cells, so you could not put a 2 cell li po on it:-

http://www.hobbyking.com/hobbyking/s...idProduct=9449

With all of these in runners the case is 36 mm dia so room is limited in the front as it would be on the Mega, but price at $26
Thanks for the info. Do I gather that the above link refers to a motor that requires a gearbox? Sorry for all the questions, but am still new to this electric flight lark!!
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Old Jan 08, 2010, 09:55 AM
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Thanks for the info. Do I gather that the above link refers to a motor that requires a gearbox? Sorry for all the questions, but am still new to this electric flight lark!!
No you can run this direct, but the prop may be on the small side.
Basically the Kv is the revs per volt, therefore if you multiply the Kv in this case 810 by volts which on a 3 cell Lipo would be approx 11 = 8910 rpm.

If you could use a 2 cell it would be 810 X 7.5 = 6075 rpm, so you could throw a bigger prop.
It has a 5mm shaft that is good as it is stronger to take harder landings.
Do not even think of running a direct drive with a 3.17 shaft on it as it is bound to get bent or break, at some time or another.

Any motor that has a gearbox fitted to it, needs a 3.17 dia shaft to fit the gear to drive the gearbox.
This opens up more motors as the Kv can be higher say 2000 - 2800. If you then multiply as above using the nw figure, you get say 2800 X 11 Volts = 30800 rpm. Devide this by the gearbox ratio say 4.4 to 1, which is a gearbox that is available, you get a shaft speed of 7000 rpm.
A 2 cell will reduce this futher as described.

It depends on what you want to do, if just for sport flying, then the cheap $29 will suffice if you intend to enter comps then I would go down the geared drive route.
You only get what you pay for as in any persuit that you want to do.

If you are unsure as to what to do go for the link I published earlier on this thread http://www.westlondonmodels.com/prod...20-6XL-Geared/

I see that you were in the US a little while ago, if you have a contact there or are going again, this is the motor I would recomend as I have used it personally & it is very good for the price with a gearbox. You can order it from here but by the time you have paid postage duty etc you might as well go to West London Models for the other link. http://www.nesail.com/detail.php?productID=3212
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