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Apr 18, 2013, 09:50 AM
It's a fine fiddly business.
Robert R's Avatar
Robin,
The Albatross is beautiful and certainly not over modeled. The only other Albatross model that I have seen is one done by Laddie Mikulasko of Canada. It was his Albatross article, done about 15 years ago, and some Keith Shaw articles of about of about the same vintage that got me thinking about a Boeing 247. I sent some very bad plans of my own design to them both and to their credit they both responded kindly and helpfully. I did get a hot wired foam fuselage done but my design and building skills needed a few years to develop before I was ready to try again.

I love the Albatross.

Thanks for another course in the visual feast.

Robert
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Apr 18, 2013, 10:11 AM
...design-build-fly-publish...
eye4wings's Avatar
Yes Eddie, there are more of us 'lightweight modellers' about as the years go on it seems.

I seem to have become less conventional in my methods over recent years but my weights are about on a par with Ivan P, the main difference being that I have dispensed with the internal stick frames. I reckon that if there has to be a balsa skin round it then why not make it work for its living - so mine start with the skin curved across the grain by the addition of part formers and the balsa that would have been part of the frame moves out to become longerons at section joints. Theoretically I should have saved some weight over Ivan, but knowing I can't really build any lighter to advantage I get less bothered by a little weight added elsewhere.

The disadvantage of light, slow models is of course that they don't like wind so much - or maybe that's just me not wanting to fight a model through turbulent air any more. If it stops being what I think of as fun, I tend to stop doing it!

The Albatross was quite a light airframe but of course (as you can see) it had to carry two packs of 2,000mah NiCads and those old brushed motors were hard pressed to 'pull the skin off a rice pudding' as my dad used to say. These days of LiPo cells and brushless motors you hardly hear of an underpowered model.

It's great being able to see what other modellers are getting up to on forums like this - otherwise I'd just be beavering away in my workshop ploughing my own furrow as they say.

Robert, a hot wired fuselage sounds like fun - presumably you did it in a number of lengthwise sections... or have you found the blank-bending method?
I used it for a pair of elliptical Spitfire wings. Use a conventional template for the root section but a half template for the tip, prop under the blank to bend it with a weight on root and tip then cut one surface. Turn the blank over and prop it as before to curve the other surface and use the tip template the other way up and at the end of it you have your elliptical wing curving in front view as well as plan. I overdid it the first time though and landed up with a wing that thickened in the middle!
Last edited by eye4wings; Apr 18, 2013 at 10:26 AM.
Apr 19, 2013, 08:19 AM
What could possibly go wrong?
nickchud's Avatar

Speed Controller for 4 motors


This combination of Speed Controller for 4 x 20A motors along with these motors Should be useful for anyone planning a 4 engine plane. The supplier of the motors claims that each one can use 199 watts at 12.5 amps on a 4S1P battery, or 134 watts at 11.86 amps on 3S1P. And they're designed for large, slow props, ie 935 Kv. It wouldn't work out as an expensive arrangement and it would certainly reduce the wiring spaghetti by a lot!

I'm doing some drawings for a DH-91 Albatross, so any advice from Eye4Wings or anyone else would be very much appreciated.

Cheers

Nick
Last edited by nickchud; Apr 20, 2013 at 01:52 AM. Reason: fixed the link to the motors
Apr 19, 2013, 09:50 AM
...design-build-fly-publish...
eye4wings's Avatar
Hi Nick,
I had got wind of your idea for an Albatross before, so you must have mentioned it somewhere else?

HobbyWing stuff seems pretty good, I have used their ESCs and uBECs and have been happy with them... meaning they do what they are supposed to do.

That 4x unit would probably be good for a small model (perhaps around 60" span?) because the 20A max is about half what I tend to work my motors at. Is that about what you are aiming for?

At that size the nacelles would not be big enough for the entire power train to be discrete in each nacelle, which is my preference, so makes sense with one pack of cells in the nose.

The problem looks to me to arise when trying to reconcile a 4S pack with small motors which have generally higher kV and would not then be using a slow-fly prop. The link for the motor came up as 'product not found' so I am in the dark on the proposed motors.
Apr 19, 2013, 10:55 AM
Registered User
abroadhurst94's Avatar
Link worked earlier, these are the motors posted before but found on another site, for some reason the other link won't work for me either now
http://www.emaxmodel.com/views.asp?hw_id=1241
Apr 19, 2013, 12:14 PM
It's a fine fiddly business.
Robert R's Avatar
"Robert, a hot wired fuselage sounds like fun - presumably you did it in a number of lengthwise sections... or have you found the blank-bending method?"

Robin,

I did a number of lengthwise sections then glued the 10 or so sections together to make a right and left hand half shell. I wasn't too bad, I should have cut the sections a bit over sized in thickness so that I had material to sand the fuse into a smooth contour instead of a series of steps. I didn't finish that project. I just wasn't happy with the way it was turning out.

Robert
Last edited by Robert R; Apr 20, 2013 at 03:20 AM.
Apr 19, 2013, 01:43 PM
...design-build-fly-publish...
eye4wings's Avatar
I did the nacelles of my 48" Tigercat that way many years back Robert, but sanded the joints lightly. That can be problematic if using Copydex! Sandpaper can start pulling the adhesive out of the joint - you must be a bit more particular than I am ... I normally ignore minor imperfections reckoning nobody is going to notice them when the model is in the air.
Apr 20, 2013, 02:01 AM
What could possibly go wrong?
nickchud's Avatar
I've fixed the link in my earlier post to the motors in the quad setup. The retailer changed his page to emphasize that the 10" props, included in the price, are for use with 3S1P. Even with this arrangemgent, they use 134 watts each. You can get 200 watts with 8" props and 4S1P. That sounds like plenty to fly a 5lb or 6lb scale airliner. To keep the weight down there, with balsa, it might be necessary to keep the size to about 72" ws.

Apr 20, 2013, 07:22 AM
...design-build-fly-publish...
eye4wings's Avatar
Nick,
Funny how memories come back - when anyone mentions 72" span I think 'four speed 400s on 7V'... which is only about 65 W per motor as they burned out very fast at anything over 9A. So although with that power they used to struggle you're talking almost 3 times the power.

I'm now thinking much more size than my original estimate of 60"... possibly that power might even fly my old design!
Speed 600s on 7cells would have been about that power...

Ooh, I'm starting to get excited!

I'm experimenting with a mix of depron and balsa at the moment... could be the way to go...

I can't see a price on those motors - does that appear once you log in to their site?
Last edited by eye4wings; Apr 20, 2013 at 08:30 AM.
Apr 20, 2013, 10:17 AM
What could possibly go wrong?
nickchud's Avatar
Hi E4W!

They're 12.95 each, including two 10x4.5" props and bullet connectors. A good deal I think!

Apr 20, 2013, 10:33 AM
...design-build-fly-publish...
eye4wings's Avatar
Yes indeed - that's a GiantShark kind of price (which is my kind of price - I'm cheap too!)
So about 50 for motors, 20 for 4in1 controller and about a fiver each for retracts... still worth having a look at HK I reckon - if it's all available there it would save on postage. (I told you I was cheap!)
https://www.hobbyking.com/hobbyking/s...m_1pc_54g.html

I was interested (excited) enough to look out my old drawings (which is why I was looking at retracts - see my comments about my doing the retracting wheels wrong) and found that, surprise surprise they are to 1/13 scale, so it seems I could be a lot more helpful than I thought at first. This is starting to look more like a partnership!

In fact how do you fancy going for a joint publication?
Apr 20, 2013, 03:37 PM
What could possibly go wrong?
nickchud's Avatar
Quote:
(I told you I was cheap!)
Any 4 motor system is expensive and fiddly. And wiring adds to the weight. I got my 4 way speed controller today. It looks very chunky and well made. It weighs 115gms including the female bullet connectors. Surprisingly, the output cables are thin, (length: 250mm/10") thinner than 13amp mains cable. Still, that's motors and speed controllers, most of the wire, weighing in total 335 gms, that's only 12oz altogether. A good start.

A joint publication? sure, I'd like that. Are you thinking we each build from the same plans, or not? I'm thinking that building wings from balsa is pretty much a standard thing. Fuselage on the other hand? I think Ivan Pettigrew would build a box frame and then add segments around the outside to support a 1/16" skin, like this. Then I would have a look at your plans and, possibly, follow them instead.

Apr 20, 2013, 03:54 PM
...design-build-fly-publish...
eye4wings's Avatar
Sounds good, let's talk about it...

My fuselage method comes out at about the same weight as Ivans, but I start from the outside instead of the inside. I reckon if you're going to skin a structure it's worth making the skin work for its living!

These 2 pics should give you the idea.
Apr 20, 2013, 04:40 PM
It's a fine fiddly business.
Robert R's Avatar
Quote:
Originally Posted by eye4wings
Sounds good, let's talk about it...

My fuselage method comes out at about the same weight as Ivans, but I start from the outside instead of the inside. I reckon if you're going to skin a structure it's worth making the skin work for its living!

These 2 pics should give you the idea.
Now that is interesting!
Robert
Apr 21, 2013, 01:34 AM
What could possibly go wrong?
nickchud's Avatar
I googled that emax mt2213 motor and found a couple of UK suppliers listing it for less than 10!



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