I'm drowning, in bits of an Mu28

[Happy Days]

For something over 2 years I’ve been pestering Fred to find me a manufacturer of a highly aerobatic 4 mtre glider that I could buy for under 300 euro. He told me time and time again that a plane of that size, in flying condition, is not to be had anywhere and that I’d have to build one to get it at that price.

Here I am then, 2years later and as an englishman I must admit the words stick in my throat, but yes, what the frenchman said was right. There is indeed no such ARTF glider in the market at that price. (BUGGER)

So here I am today, feeling more than a little uncomfortable having just taken delivery of a very large parcel from a company called Miniplumes.
Inside is a “short” kit of parts for a 4mtr.  Mu28.
From what I can make out there was only ever one full size version of this glider ever built, and it’s still flying now as far as I understand.

(Here’s some info for those who might be interested http://en.wikipedia.org/wiki/Akaflieg_M%C3%BCnchen_M%C3%BC28 )


Having never successfully built anything like this sort of very basic kit before, and certainly nothing of this size before, at the moment I’m feeling as though I’m immersed in a cauldron of doubt, ignorance & anxiety which has been seasoned with a liberal helping of fear that I may have bitten off rather more than I can chew. Add to that the fact that I can’t swim and you’ll have a fair idea of my inclination to leave all the parts in the big box and offer it up for sale on eBay……..Any buyers out there?
Oh,……okay I’ll open it up and have a ‘look-see.’

ooOOOOooo!!


How about the wings?

I'm not sure I'll be able to build them on this worktop,.....HELP

But what's this? is that a canopy or some kind of top hat :shock:

This is all looking very difficult! i'm gonna need lots of help. (How on earth is it all supposed to fit together. :!: )
Perhaps I'll just stick it all back in its box and forget about it :? What do you recon lads?

Keith

[JohnPearson]

Nice looking glider Keith, so you have to do some building, not a problem, just take your time Keith and we will all help you produce a fine looking model, 'fit for a king' :lol:

[Happy Days]

But I’m a republican John, I think Britain should rid itself from the plague of monarchs that it’s endured for the past thousand years …..but don’t get me going on that subject……. :roll:

Returning to more civilized topics, thanks for your comments John. Er, how about I box it all up and post it to you, and then you post it back when it’s ready to fly!      No,..... I didn’t think you’d agree to that. :cry:

Oh well, guess I’ll just have to persevere.
So here comes the first question. It relates to the wings and their re-enforcement.

My friend Fred has suggested laying carbon strips into the foam cores. Another friend of mine, Brian, thinks that the wings should be strengthened with fine glass matting.
Do I hear any advance on these two offers? :?

Additionally, still thinking of the wings, I’m inclined to try Air brakes. (Never had a plane with airbrakes before, only Crow brakes.)
This question comes in two parts :?:

1/ If I use airbrakes should I use the type where the brakes emerge from both top & bottom of the wing, or just from the top of the wing.

2/I’m cautious of removing material from the core of the wings (for airbrakes) on the basis that the more material I remove, the weaker the wing will become, so maybe I shouldn't fit airbrakes at all but simply rely on crow braking.

Anyone got any thoughts/advise on this matter.

Yours, perplexed,

Keith

[Richard Boyd]

Keith , what a stunner !!!!!!!!!!
I am jealous :clap:
I am really looking forward to 2012 to see her fly.

[Happy Days]

2012!!! :shock:  :shock:
Are you mad? I was thinking more of 2013 or 2014 or maybe...........

Keith :lol:

[Alan_Perse]

Nice model Keith. You finally got a scale model. Hopefully you will get it in the air.

[Happy Days]

Thanks Alan.  Fred beat me into submission.

I was looking for a model that would give me the performance that I wanted along with being a little unusual. (I prefer the weird and wonderful things in life. I like to think the same description could be applied to me. :roll: )
So when I heard about this one-off glider , I thought ‘that’s the one for me!’
It’s supposed to be unique, but to my eyes it looks very ‘Fox‘ like.

K.

[gerryb]

congrats keith, a fine model for all those crazy aerios you want to try out, now you have no more excuses!!

a big model can be fairly daunting at first but if you spend time thinking things through before you build, you'll be fine. divide up the whole project into smaller jobs and tackle a small job like the rudder first. when it's built, it's out of the way, finished. if it goes pear-shaped on you, you're not at too much of a loss, easy to get going again. hold on......, this sounds like building a big version of a phase 6! how many times have you done that before???

re airbrakes, schempp-hirth type (up-and-down, scissors-action type) can be a lot of bother somethimes and you have to be careful to not let rain in the a/b boxes. i stick with the upper only a/b's, still very effective and less likely to snag on the heather when landing. on the full size mu 28, the inner flap section looks very small for crow brakes (check out airlines.net for photos). you could always make them bigger to suit yourself.  

re spars, if the wings are deep enough, have you considered plain and simple spruce spars? still a very good way to carry loads.

best of luck keith, keep us posted

[Brian]

Hi Keith,
Re glass v carbon tows - you can do both or either.
I was just explaining how easy is is to sandwich in some glass when skinning a foam panel.It will add to the stiffness a lot which is good for an aerobat.
Brakes do complicate your build quite a lot.
Crow (easy with RC - not with full size) is very effective and simple to do.

Brian

[Happy Days]

Yes Ger, I was thinking of much the same plan of action. I’ve been sitting in the workshop looking at these foam wing cores and trying to think of all of the potential problems I can before I actually start the job.  (As for it being a big version of a Phase 6, I wish it were. At least I’d know what I was doing .)

(Incidentally I can’t start on the rudder as it hasn’t been included in the kit. There are a couple of other bits that have been left out as well. I’ll notify Miniplumes of all the missing parts on Monday.)

Referring to air brakes:

Thanks to both Ger & Brian for you input. This is the sort of information that I need to acquire so I can make an informed decision as to which way to progress the build.

Perhaps I could say at this point that I am always very interested in receiving info from ALL experienced builders.
Even if I don’t necessarily adopt a particular builders suggestion that does not mean I don’t value their opinion. I DO!
Air brakes are a case in point. I know Fred is a great advocate of them, and I can see the advantage in not causing the plane to Balloon, as happens when applying Crow braking. But I like to hear the other side of the argument as well.

In fact, on this matter of slowing the plane, I think I’m going to come down on the side of making larger flaps and to use crow braking.
Reason: No need to make holes on the wing to fit brakes. No risk of flaps/spoilerons jamming, as I understand A/R’s can.
So, that’s one problem sorted!

Now,………….back to the question of how best to strengthen the wings. :?:

[Fred]

Hello from>>> Work! Yeah, still at it!  :!:

Very nice Keith!  :clap:
When people think about aerobatic gliders, they all think Fox and Swift first! But the Mu28 have everything we want in models, all the proportions are perfect for our sport!    And I'm sure you will be the only one at the slope with this type of glider!  

So, very quick reply anyway, for the wings, you don't have 300 solutions!
Vertical spar, I would add Carbone top and bottom for a I spar, and that will be more than enough like that!
Simple, quick and easy!
You can alsway add fibreglass layers (one full wing, one from root to ailerons, one root to airbrakes, and finally, one root to wing joiner box), but that might be overkill as with a good vertical spar, it's plenty on its own.

By the way, for the other that might be interrested, I did a how to a while ago. This is what I do, but you have hundreds of other ways, but these ones are simple and really easy to put in place.

http://www.gliderireland.net/index.php/techniques/vertical-wing-spars
http://www.gliderireland.net/index.php/techniques/composite-spars

For the airbrakes Vs Crow, I will always chose airbrakes at the slope. Maybe a question od taste, but Airbrakes generate way less induced effect that crows, and when you are close to the ground, in turbulences, having full controls, especially at the ailerons, it's appreciated!  
Airbrakes, they are your throttle, it's a proportionnal channel!

Anyway, that's it for me for now, time to go back home, 3 hours sleep, and off to work again!  8-[

[Happy Days]

Still working at half past midnight? :shock:  You must be earning a fortune!!  (No wonder you’ve got so many models!!)Thanks for your input on that matter Fred.

In your link to those drawing in the previous post it shows the spars being fitted and then the final sheeting being fitted to cover the wing……I’m wondering if the wing joiner box should not be fitted first into each wing half before the final sheeting is put in place. Otherwise how could I fit the joiner box into the wing half?

Thinking on……. Before I can fit any spars whether they be carbon, spruce , or any other type I first have to create a single wing half from the three wing core sections that I’ve been supplied with (3 part cores for each wing half).
Has anyone got any suggestions as to what I could reasonably get my hands on that would be at least 2meters long and flat enough to lay the three sections on while I stick them together to make one straight wing half?
Would laying them out on a wooden floor  be okay do you think? (The floor looks pretty flat to me)

K.

[Fred]

Hey Keith (yes, from work... Again!  :!: )

Don't use the floor!
To glue the sections between them, use white glue, as simple as that.
You can use epoxy, but you might see where the sections are joined together after sheeting, as epoxy will create a hard spot. Doesn't matter much anyway, just a question of look really  :wink:

To keep them straight, glue the section in the foam they came from.
On the sections, where they join, I usually put a strip of Brown tape to avoid excess glue to glue the wing to the foam base!
Cling film is also what I use when sheeting etc.

For the wing, the process is very simple.
Sheet the top of the wing first (after having added a strip of UD carbone, peel ply for you ailerons if you want to use that (recommended to have a smooth aileron's flow))!
Tip the wing upside down, cut all your grooves for servos, spar, wing joiner box. Glue all that.
And sheet the bottom of the wing.

For the wing joiner, it depends of the type of spar you want to do at the end. With a vertical wing joiner, it is very easy to glue the wing joiner box to it.

Hop, back to work!

[Happy Days]

Thanks for your comments chris,

I have to admit my mind keeps drifting back to this matter of which way is best to reduce airspeed for landing.
The benefits of flaps/ailerons verses airbrakes?

 Of course I could fit all three controls into the wings and gain all the benefits except, that as Brian says, it would complicate the build and add weight. As I’ll mostly be launching this bird while on my own, weight is a matter of concern. If it’s too heavy it’ll need high winds to ‘perform best’ but I don’t fancy trying to launch a 4mtr model, by myself, in high winds. So I want to keep the wing loading as light as possible. For this same reason I probably wont be glassing the wings either.

One good thing about this build, it’s got my old ‘Grey Matter’ working overtime. (Just hope I make the right choices!)

Keith
I used to be indecisive, but now I’m not so sure!

[gerryb]

hi keith,

re building board... in case you missed it, DON'T USE THE FLOOR!!!

ok, no more shouting. i have often used old style plain flush doors ( nothing to do with toilets, unless you're behind one, the door i mean, oh forget it). these are usually quite cheap and come in a variety of sizes. something about 6'8" x 2'8" would be a good idea. 2'8" would mean you could have both wings on the board at the same time. a little ingenuity and you could have the legs on castor wheels for easy manoeuvreing.

in one of the photos i saw a roll of veneer, obechi i think.  is that your wing sheeting? wether it's obechi or balsa you use, copydex is a good adhesive for the sheeting. it is a water based latex glue and will not dissolve the foam.