Oodalally

[kc]

It's pretty disappointing to get the plan and then find it's not as the designer intended and nobody has ever flown one to the exact published design! No doubt it will fly but maybe not quite the same.

I did a quick tracing of R2 and it doesnt look to me as though the R2 rib will fit the fuselage shape which is larger ( I could be wrong its difficult to tell ).......maybe they used R1 shape. I assume it should be R2 shape as that's where the wing contacts the fuselage ( in my view). The problem is that if we builders try to fit the wrong wing shape to the fuselage we change the incidence of the wing inadvertantly. ( no datum lines are shown on the ribs or the fus side. )

Lots of DB designs have slotted 3mm ply but dont have a 'cap' over the wire, it just protrudes a little into the fuselage and relies on the hole in the beech cross piece to stop sideways movement. Works well.

[Glenn Howcroft]

Just to say thanks for a really great design Peter.

I'm actually going to build this one .. my first plane in nearly 2 years !!!.

I caught the helicopter bug and have been learning to fly, and fix the bent ones, for a what seems like ages now. Can't wait for the smell of superglue, the balsa dust and the cut fingers ... again. It's going electric though .. can't do with all those smelly, noisey things any more.

Will be using a Emax 2820/07 motor, swings a 11-12 inch prop on 3 or 4 cell LiPo. More or less a direct replacement for a .32 i.c. engine so should work fine. Have used the same setup in my OD Tucano of 56 inch span and flew well on 3s, but will probably go to 4s for the extra grunt.

Will post some pics when I finish it.

[Andy48]

The Emax 2820 with a 4S battery and a 12x6 will give about 2.3kg static thrust at about 50 amps on a freshly charged battery.

[Colin Leighfield]

Peter. That's an attractive design. I was interested in your use of a (by normal standards) relatively small tailplane which is entirely adequate because of the length of the moment arm and you describe this in RCME.

I was lucky recently to acquire a partially finished Mick Reeves FW190D, which I have finished and flown. It has the scale size tailplane, which again is small. Models of 190s often seem to have larger than scale tailplanes. However this one is rock steady and responds beautifully to control inputs, it has no vices at all. It looks like the formula you describe, a long moment arm doesn't need a large tailplane area and this is certainly the case with the 190D.

If I can clear the bench of ongoing projects I'll do this one, it's a handy size as well. I'm not fussy either way with I/C or electric, but I think I'd stick with I/C in this case.

[Peter Miller]

I once designed a scale Macchi "02 Folgore for .15s. Plan was in AMI. That had a really minute tailplane and not that long a moment arm. Flew perfectly.

Designed a .25 size version for the Cambria range which was never manufactured. That also flew perfectly.

Since then quite a, lot of my designs such as Minnow and Little Bandit have had small tailplanes.

I think that the CG at 25% is one of the main factors in the handling.

[Colin Leighfield]

On reflection, I think you are bang on with the point about the forward cg. In level flight the cg and cp must co-incide with each other, so I suppose a forward position has the same effect as lengthening the moment arm, to some degree. One other thing that surprises me about the 190D also is just how little elevator movement it needs, the reverse of what I'd expected with the very small tailplane and elevator. You live and learn, I suppose. Reading your write-up on Oodalally in RCME I noticed that your recommended movements are also not excessive, which says a lot about it's controllability.

One question if I may Peter, is a 30 four stroke an option?

[Peter Miller]

I never need high rates on the elevators unless I want to do wild flick rolls.

I feel that a 30 FS might be a little under powered for the model. a good .25 two stroke has more power and I would say that that would be the minumum.

[Steve Adams]

I will definatly be building Oodalally,as soon as work + family commitments allow! I have an Irvine 25 Mk3 abc(twin ball race) engine to go in this n.i.b although 15+ yrs old! This motor cost me 75quid back in the 90s(dear by 25 standards) and i beleive that a special(to me) British designed and made engine deserves an equally special British design to go in!

Many Thanks for another wonderful design Peter,Keep em coming

Kind Regards

Steve

[Terry Walters]

Posted by Peter Miller on 11/03/2013 11:18:35:

I was more concerned that the ribs had been thinned down by 1/8". Probably won't make much difference to the flying though.

I like the look of this one Peter it looks great in those colours too.

I could probably build it out of stock balsa but I have been trying to work out what width the ribs were originally. The plan says 3/32" - if that's the result of 'thinning down' by 1/8" then that would be 7/32" and that doesn't seem right either so I assume they have been 'thinned down' from 1/8"?

I also notice the plan isn't available from MHS yet - is it going to be?

Terry

[kc]

I assumed Peter meant the rib height was 1/8 less not the balsa thickness! ( 3/32" thinned by 1/8" would be a minus thickness  -1/32  )

The magazine with plan appeared in WH Smith on Saturday and would be much cheaper than buying a plan later. It is, of course, double sided whilst MyHobbyStores plans are normally only printed on one side.

Edited By kc on 12/03/2013 11:15:16

Edited By kc on 12/03/2013 11:21:04

[Peter Miller]

I meant the thickness of the wing. Instead of a 13% thick wing it is only just qbout 12%.

However I have wings wings with 12% thickness andf there isn't much difference in handling.

I asssume that the plan will be available from MHS. I am interested in the question. Does that mean that the plan available from MHS is not the same as the one in the magazine?

I imagine that there will be a set of parts too but I don't know. However the popularity of the design would seem to make this worth while.

[Terry Walters]

Posted by kc on 12/03/2013 11:11:46:

I assumed Peter meant the rib height was 1/8 less not the balsa thickness! ( 3/32 thinned by 1/8 would be a minus thickness -1/32 )

The magazine with plan appeared in WH Smith on Saturday and would be much cheaper than buying a plan later. It is, of course, double sided whilst MyHobbyStores plans are normally only printed on one side.

Edited By kc on 12/03/2013 11:15:16

It all makes sense now - I said I thought I may have missed something.

As a subscriber I have the Mag plan but I like one to cut up when building and use the double sided to read those bits I have just covered up with half a balsa tree!

Thanks

Terry

[Terry Walters]

Just seen Peter's comments too - thanks Peter

[Colin Leighfield]

Peter, thank you for the advice.

[David Ashby - Moderator]

Posted by Peter Miller on 12/03/2013 11:12:59:

I imagine that there will be a set of parts too but I don't know. However the popularity of the design would seem to make this worth while.

Yes, there will be Peter.

[kc]

Terry,

To save cutting the original plan I found that a printer/scanner/copier makes exact size photocopies at the touch of a button and can be used to copy parts such as wing ribs, formers etc on A4 paper. If you can choose one that does not have much of a step around the top it is easy to position even the middle of a plan. You dont need to shut the lid down - - just put a sheet of white card on top with a weight ( Argos catalogue! ) to ensure a clear copy. Even a long fuselage shape can be done on A4 size with sellotape or Magic tape if you draw on joint marks first.

[Hugh Coleman]

Nice design Peter.

Very Pretty.

Any particular reason why you went for a tapered wing?

I wonder how it's performance/flight characteristics would change if you made the wing parallel with R1 as the template for all the ribs?

Keep them coming!

Cheers,

Hugh

[Peter Miller]

Posted by Hugh Coleman on 14/03/2013 10:15:45:

I wonder how it's performance/flight characteristics would change if you made the wing parallel with R1 as the template for all the ribs?

Why don't you try it and find out?

[Hugh Coleman]

Thanks Peter,

I may do just that (Maybe make two wings, one of each).

Cheers,

Hugh

[Peter Miller]

Now that would be very interesting.

[Piers Bowlan]

Peter, we are a bit spoilt for choice now what with your Dragon Dancer 2 and now Oodalally designs. They both look great and very similar in that you flew both with a 32, so how do they compare as far as performance and handling goes? Do you have a preference as far as the flying is concerned?

Piers

[kc]

A parallel chord wing of root chord & same span would be 596 sq ins rather than the 500 of tapered wing, so maybe reduce span? Also CG will need to be re-calculated.

My quick look at rib percentage seems to show that root is about 13 percent while the tip reduces to about 12 percent. Maybe this is because of the aileron being a constant 1.25 inch extends the actual chord more at the tip ( ie same thickness is a lesser percentage of the extended chord ) I do think that somebody ought to quickly build a wing to the published rib shape to see if it works as well as the original.

[Peter Miller]

Piers: It is over four years since I flew Dragon Dancer. I seem to remember that it flew in a very similar way to Oodalally. I know that it was fast and aerobatic and had no bad habits.

Really the choice is more about which you prefer the look of.

KC: You would get quite a bit more area with the parallel chord so either some reduction in span or a bigger engine might be options.

The CG should be at 25% root chord so not too much recalculation.

I would be happy to supply a copy of the original plan at cost for the prints and postage if you want to try that.

Me? I am just finishing another plan and then....

[AJ]

I have been building the Oodallaly and have just started the wings. I am building from the mag plans but am struggling with the rib sizes. The rib cutouts r1-4 shown on the plan are not the same length as the ribs shown in the wing layout plan. eg r1 is cut at 246mm length but in the wing plan it is 248mm. Where/how do I add the missing mm back? If I just cut the ribs longer they will end up too thin at the ends and if I just enlarge the plan the spar slots will be too big and/or in the wrong place.

Both wing plans are the same size and based on the projection of the le & te lines it would appear these are the correct dimensions so I just need to add the missing mm into the rib cutouts, but where?

Here are the dimensions measured from the plan. Cutout size first then wing plan size, all in mm.-

R1 - 246,248

R2 - 240,242

R3 - 230, 232

R4 - 220, 221

R5 - 210, 210

Any ideas appreciated.

[kc]

Are you allowing for the 1/8 ply dihedral brace ( part is drawn a few inches above the RCME Plans logo ) which fits in R1 and R2?