Preparing for the 2016 Mass Build

[Erfolg]

In many respects David's suggestion is very typical of what happened in the past in full size aviation. A different engine would be installed to suit a customers wants. It could be a a horizontally opposed cylinder as Continental engines, or a Menasco. There has even been a DB 601 engine installed on a Spitfire, an inverted "V", all producing a very different nose profile.

What matters is that the important relationships are maintained of the Ballerina, the chord, span, tail moment, general constructional details, that all are Peters design concepts. Much else are minor details.

If Peter was building one of the models, I would not be surprised if the engine were to heavier, than initially used, that he would shorten the nose, or conversely lengthen it for a lighter engine. If Peter could be persuaded to build an electric model, I would expect a different nose yet again.

I think that much of what the rest of us will be doing is acting as "detail draftsmen", who are fearful if they will get approval from the Chief Engineer.

[David Hayward.]

Hi, I'm wandering if anyone can help me with a question of side and down thrust for the Peter Miller plan 'Ballerina'. There does not appear to be any side or down thrust shown on the plan. I am not questioning Peters design but I am wandering if I am missing something? I am in the early stages of cutting out all the parts currently and looking forward to putting it all together.

Can anyone advise? Put me in touch with Peter?

Your help would be greatly appreciated. Thank you.

Edited By Pete B - Moderator on 07/12/2015 18:47:14

[Peter Miller]

No Side or down thrust. The aircraft is set up with 0-0 incidences. The centre of drag is below the thrust line so no down thrust.

The lack of side thrust is only likely to cause a slight swing to the left on take off...use the dab of right rudder to correct if needed.

Note that I have never seen a full size aircraft with side thrust. They normally use an offset fin if they really need it.

NOTE . None of my designs have side thrust and only the odd one with a very high wing position where the dentre of drag is well above gthe thrust line need down thrust. e.g. The Slingsby T-31M for example does need down thrust

[AVC]

I agree that a well designed, built and trimmed plane shouldn't need any down thrust unless you intend to fly full throttle all the time. And for the side one, I'll borrow the words from David Anderson in the building article of his Arado 96:"don't add any right thrust, learn to use the rudder instead.
Having said all that, for those who feel more comfortable, I don't think I'll do any harm to add 1.5-2 degrees in the building process. I won't do it, though

[Paul Marsh]

I will be building the Ballerina. Do fancy the 115% version as well, maybe do the normal size one and a larger one as well. Got the parts cut out already,anyway, but will start it over the Xmas period, and probably be finished around early New Year.

[Clive Hall]

Seconding Peter Miller’s comments on the lack of offset thrust on full size aircraft, consider what would happen to aircraft with Merlin engines with a few degrees of side thrust; they would have to be much fatter in plan view to get it all in. I know that the Fairey Firefly had a strong swing to one side on take off and that lots of rudder had to be applied in good time or it could barely hold it, so that would have been a case for sidethrust. Instead they depended on pilot skill.

Note, however, that downthrust was used on some WWII fighters, notably with Griffon engines and, of course, the P-51 Mustangs.

[Peter Miller]

The difference between the fighters with down thrust is that tey will have had wings set at positive incidence. My designs do not.

As I said regarding side thrust, quite a few aircraft had fins offset. Now if you want to build that in , how much do you need and how do you change it?

[Clive Hall]

I do not know how to calculate fin offset, but I tried it on a Flair Hannibal. I took a SWAG and by sheer luck it worked. [SWAG —scientific wild-ass guess.] There is some mythology about offset fins, to the effect that they will cause endless trouble on low power. Apparently they don’t, probably because the offset is calculated to work at high speeds with a strong slipstream and has little effect, if any, on the glide. Not that WWII fighter pilots tended to stay on board if their aircraft were disabled to that extent, so maybe it didn’t matter to them.

As for changing fin offset, you can’t, so it’s safer to leave it alone unless building a scale model where the amount is documented.

Incidentally I hope to join in my first Mass Build: how does one go about starting a build blog?

[Peter Miller]

It is quite easy. JUst click on All topics at the bottom of ghe list of topics top right here. Then when that comes up click on Start new thread.

Fill in the title, the subritle if wanted and find a suitable main subject possibly the same as this thread 2016 Mass Build  is in and start filling it in as a normal post

Edited By Peter Miller on 08/12/2015 13:52:20

[Beth Ashby Moderator]

All the items to help with the mass build (including the plan by itself along with the December issue of RCM&E) are now up on www.myhobbystore.co.uk, you can shop them HERE.

You can also find all the information and discount code for each item HERE.

Beth

[Clive Hall]

Thanks, Peter, just what I needed. Will be starting in a week or so.

[Craig Thomas]

I've been thinking about what to cover the plane in once finished, providing the plane, providing it is a successful build of course. I've only ever covered 3 planes. One using solar film (didn't think much to that) and the stuff you can get from hobbyking (mush better to work with) and fancy using something different. I fancy a bash at using solartex. But looking at the price of it its not cheap. Anyone know where it can be sourced cheaper? Hobbyking do 5 meter rolls for ?36. Is that as cheap as I'm going to get it?

[Peter Miller]

Pesonally I prefer Solarfilm Supershrink Polyester.

I don't think taht you will get Solartex any cheaper

[Geoff S]

I tried to find a cheaper supply of Solartex silver for my DB Tiger Moth (G-ACDC) and everywhere seemed to be about the same price for smaller amounts and HK didn't stock silver. It's good, but dear. HK film is really good as well as cheap and I notice Banggood sell film too in 5 metre lengths for around £10 posted (probably the same as HK).

I made a second attempt to buy a Decemeber RCME today and failed. It's funny, the newsagent I get the odd mag from usually has copies of both RCME and another but not this month. Perhaps they've been grabbed by MBers

Not sure if I'll build a Ballerina but I am tempted. I'm a digital only subscriber so I don't get the plan and buying a copy at £12.50 is more than a whole magazine! If I do decide to join in it'll be electric and I'll only buy the cnc ribs. If the ribs are the same I'll cut my own. I'm sure I have enough wood in stock and probably a suitable motor so it'll be a cheap build for me.

Geoff

[Biggles' Elder Brother - Moderator]

Posted by Clive Hall on 08/12/2015 13:46:27:

Incidentally I hope to join in my first Mass Build: how does one go about starting a build blog?

Hi Clive, we start the Mass Buiild all together on the 1st Jan 2016. You can of course be doing all your preparation - source power units, wood, plan etc in the meantime.

BEB

[AVC]

I've just received the below bunch of wood from Slec. With this plus some other bits I've got in the workshop should be enough to complete the airframe.

BEB, I promise I won't touch anything until January

Alex

[Biggles' Elder Brother - Moderator]

Good boy!

BEB

PS Its OK to look at it!

[Glyn44]

I'm gonna say goodbye for this build. Just decided against it with it being primarily an I.c. Which is not really my cup of tea, plus. the total cost to build a model that was not my first choice.

So I am going to find something else, but not sure what at the moment. I do hope to join in hopefully eventually, next winter perhaps. I wish you all well.

Seasons best wishes to all,

Glyn.

[Peter Miller]

Posted by Geoff Sleath on 08/12/2015 16:44:01:

Not sure if I'll build a Ballerina but I am tempted. I'm a digital only subscriber so I don't get the plan and buying a copy at £12.50 is more than a whole magazine! If I do decide to join in it'll be electric and I'll only buy the cnc ribs. If the ribs are the same I'll cut my own. I'm sure I have enough wood in stock and probably a suitable motor so it'll be a cheap build for me.

Geoff

Yes, all the ribs are the same with just variation in some for the U/C mount.

[Biggles' Elder Brother - Moderator]

Posted by Glyn Calow on 08/12/2015 18:11:17:

I'm gonna say goodbye for this build. Just decided against it with it being primarily an I.c. Which is not really my cup of tea, plus. the total cost to build a model that was not my first choice.

So I am going to find something else, but not sure what at the moment. I do hope to join in hopefully eventually, next winter perhaps. I wish you all well.

Seasons best wishes to all,

Glyn.

I'm very sorry to hear that Glynn. But to be honest I don't quite follow one aspect of your reasoning! You say "with it being primarily IC" - I don't get that. In fact I'd be happy to lay a small wager with you that:

the number of electric powered Ballerinas built in the Mass Build exceeds the number of IC ones built.

And if I'm right - how is that "primarily IC"

BEB

[Geoff S]

Posted by Peter Miller on 08/12/2015 18:19:12:

Posted by Geoff Sleath on 08/12/2015 16:44:01:

Not sure if I'll build a Ballerina but I am tempted. I'm a digital only subscriber so I don't get the plan and buying a copy at £12.50 is more than a whole magazine! If I do decide to join in it'll be electric and I'll only buy the cnc ribs. If the ribs are the same I'll cut my own. I'm sure I have enough wood in stock and probably a suitable motor so it'll be a cheap build for me.

Geoff

Yes, all the ribs are the same with just variation in some for the U/C mount.

Thanks, Peter. In that case I'll just cut a pattern out of aluminium and cut the ribs out myself. I've ordered a paper magazine on-line so at least I'll have the drawing to ponder

I'm also thinking of making a built-up empenage to save weight at the back.  Not sure if it's worth it but it's not a big job and the light shining through in the air will look pretty.  I'm a bit annoyed with you, Peter, for designing such an attractive model and tempting me from my winter path.

Geoff

Edited By Geoff Sleath on 08/12/2015 19:44:43

[Craig Thomas]

Postmans  been

Edited By Craig thomas 1 on 08/12/2015 20:03:18

[Whatgoesup....]

He came here too !

[Craig Thomas]

Wish my postman was like yours.
One thing I know I'm going to have a problem with is knowing which size wood is which. None of the balsa is labeled so I'm going to have to measure everything. As for identifying the soft balsa from the medium well, I've not more chance of winning the lottery. It all looks and feels the same to me.

[Peter Miller]

A good ruler with 1/32", 1/162 and 1/8" divisions works well.

Use the kitchen scales to weigh the wood. the heavier it is the harder.

WE can usualy test with a finger nail but that does take experience. Soth wood will take a dep groove from afinger nail while hard wood will take a much smaller one.