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Dec 14, 2008, 01:46 PM
One Idiot is plenty...
Dbox's Avatar
Quote:
Originally Posted by Thekid3418

I could add an extra layer of 1/64th top and bottom at the center section. Something that would stretch just maybe 5-6 inches out to each side to join the panels.
Thats what I am going to do.But on top,I want to do some sort of the pod which will hold wings together as well.Working on it right now and have to admit,that I am stuck with it.I dont want to screw shape of the wing with ugly looking pod,from other side ,I have to fit all electronics in it ,with square battery,which is hard to do.
Making the wing tips out of sliced depron with carbon tow in between,funny looking ,but light and strong.Have to glass it over after shaping .Just an idea.
Yuri.
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Dec 24, 2008, 01:49 PM
The Kid
Thekid3418's Avatar
I must have been a good boy this year, christmas came a day early! I got my Mubu cores, and they are sweet! They sure as heck are thin though!!! I didn't realize how thin they were going to be, i think im going to have to rethink my servo chioce. I was going to go with plain old HS-81s. Now i don't know what im going to do. Im too cheap to get nice servos for this one . Maybe i'll order some thin wing servos from HC next time i order there...Santa brought me some sweet HS-65HBs ffor my ESCAPE thats on the way. Man am i tempted to use those!!!

Anyway, the cores are ship shape. Though in my rush to loook at them i pulled one panel out and tore up the trailing edge a little (darn thin foam!!!). I've got the first wing part curing right now. Im sheeting them in 1/64th ply. My plan is to sheet everything, than glue it together with some f/g to hold the seams together. Then when it get to the time i have to do the controls, im going to give skin hinging a shot. Should be a little cleaner than plain old CA hinges. Maybe less drag too!!!

If anyone wants a set of cores like mine, you can go ahead and PM me and i'll give you the email address of the guy who cut mine. He'll probably sell them to you for 10 bucks or so plus shipping to where ever you are at! I'll put a disclaimer out though, this guy doesn't do "perfect work". It always works, but for instance, my cores don't match up exactly with chords and such. It would be an easy fix to trim some here and there, but not really worth it in my opinion. As they say "Close enough for jazz". If some has a mubu urge that they need fixed, im sure he could help you out.

Heres some pics, just for fun
Dec 24, 2008, 02:05 PM
Needs brain lubrication
biber's Avatar
Thread OP
Cool, looking forward to the build!

The set of cores layed down looks familiar to me.

Btw, Dbox, nice winglet you have there is the left one going to the Mubu or is it a template taken from another mode?
Looks close to what I have in mind for my own Mubu, but I guess yours will be finished before mine.

biber
Dec 27, 2008, 01:16 AM
The Kid
Thekid3418's Avatar
Hey biber, i need a little guidance from you. About where do you have the battery placed in relation to the wing? And about how far back is the motor mount from the trailing edge?

I want to make sure i make my pod big enough and have it still be able to balance...
Dec 27, 2008, 06:47 AM
Needs brain lubrication
biber's Avatar
Thread OP
I've dug into old pics and found a sketch of the pod layout of the first multibumm prototype.
Later minor changes have been made to the inital layout to accomodate the final molded pod.
Such as the ESC would sit below the battery instead of on top of it and the Rx was not lying flat in the front but hanging upright from the wing into the pod allowing the boat like shape of the final pod.
The general config kept the same, only everything went about 10 mm forward to get rid of nose ballast.
Note that due to the F5D limited contest rules we had to use quite heavy weight equipement.
Battery was 250 g and the brushed motor 180 g.
Generally the wing itself without the pod had a CG close to what would be needed to fly it, just one or two centimetres tailheavy.
Thus the pod including the guts should have its own CG rather a bit forward from the flyable CG of the whole.
To adapt your components to that, take a piece of balsa or foam and place the guts on that and play with it to find a config that's neat and tidy and will get the CG about right.
When the wing is finished you can do this with the scrap foam or balsa plate tacked onto the wing and get it sorted.
Saves you some of the extra lead.

I'm sorry the pic is a bit blurry, but you get the idea.

biber
Last edited by biber; Dec 27, 2008 at 06:53 AM.
Jan 15, 2009, 12:00 AM
The Kid
Thekid3418's Avatar
What happened to this thread? There was so much hype, and a few people were building them, but i haven't heard anything. Yuri?

I know what happened to mine. (#&)% Like an idiot, i sheeted them in the wrong steps, which led to a nice healthy warp in the airfoil, dang it. Cores are lost beyond repair. A few things were learned.
1) 1/64 ply wood is plenty stiff, if too heavy though
2) Everything should go together smooth as silk on the next one.

Just rushed too much to try and get it done before the end of break, my loss. I'll have to get another set and give it a shot at round 2.
Jan 15, 2009, 12:13 AM
One Idiot is plenty...
Dbox's Avatar
Hey Kid I am here.
And stuck with the pod part.Want to do it my way .There are a couple of other projects as well as a work to pay the bills.
I cut spare set of cores from 25 and 60 PSI foam.Let me know if You want them.
Free of course,just pay shipping.
Yuri.
Feb 02, 2009, 12:28 PM
Registered User
biber, does it make a big diference not having the -3 diedral? Mine doesn't have it because I only knew about it when Troy asked...

I ""flew"" the mubu yesterday and today but without much success..
I launched it with motor off, and it flew ok yesterday. Today I launched again with motor on, but wasn't with full on. Didn't have much autority with the elevators at that speed and because it was heavy wind it went to the ground and broke the prop.
Then I decided to go to slope, it was really good stong wind. Good for... a Jart! Launched, flew nicely for some moments (now with good elevator autority!), but when I started to corner it just flipped over and turned against the slope. I managed to turn it and save from the crash. Then when I turned again, it flipped again but this time it was already too close to the ground...
Didn't was too damaged, just a few more cracks in the pod.
Because it seemed to be a massive tip stall, I moved CG a bit in front. Still had good elevator autority but it flipped again! This time, pod is a mess... needs some repairs...

I have a second set of foam cores... but untill I see more flying reports I decided to give up. Really need something more reliable to fly for now and I have too much projects and repairs going on (hotliner with neu 1511/1D/6.7, Jart and a SuperGee II). And now I have to do something more "normal" or just buy something "cheap" like a sunracer (edit: or a Escape, really good price!) so that I have some time to finish the damn Jart!

Come on guys, just finish those mubu's, fly them and give good reports! Just need a good report to make a new one
Last edited by _King_Pin_; Feb 02, 2009 at 01:18 PM.
Feb 02, 2009, 06:26 PM
Needs brain lubrication
biber's Avatar
Thread OP
Big Bummer!

I can't see, what is wrong with your wing.
How do your winglets lool like,
Are the attached to the wing with a backward offset as on our prototype?
Sometimes that fixes problems with tipstalls.

I don't know how important the anhedral really is, as all our Multibumms and Mubus just had it.
But I don't think zero anhedral can be that disastrous.

I have some videos of the Mubu II prototype, not yet available to download, but I'll have them hosted and link it here.
Hope that might help encourage your again.

However I can fell how it frustrates you, Paul and I had our share of it aswell.
In such moments, it is better to back off some time and let it settle a bit.
Then some time later the thirst for adventure might come back.

biber
Feb 03, 2009, 06:22 AM
Registered User
No, winglets are not backwards as yours, that's one thing I can do easy.
Probably it's not that dificult to just cut this wing and put the anhedral, also.
This thing has crashed so many times and so hard! I don't understand how the wing is still in one piece!

Well, as I said, I'm going to buy a Escape, so that I have a good plane to fly without spending much time and money. And redirect my time to finish other projects. This will give time to "the thirst for adventure come back".

Looking forward to sse more Mubu II video!
And also, some flying reports! Come on, Yuri, TheKid, Troy! Just finish those things and fly them!

PS:Everyone here at home just love this wing. Definately that's the main reason why I'm still trying to fly it. It's just a beauty!
Feb 03, 2009, 11:39 AM
One Idiot is plenty...
Dbox's Avatar

To glass or not to glass?


Here is where I am at now.Making wipers and thinking of glassing wing.
Pod is still has not come to mind .
Your report put me in a bad mood,but so much work was done ,have to finish her some day.Just too many projects is ahead of this one.
Yuri.
Feb 03, 2009, 07:27 PM
Caution:Makes sharp left turns
Troy's Avatar
Take one for the Team Yuri. You're so close! I completely screwed up on my first try and made it work in spite of it so don't fret. As long as you cg correctly I don't see an issue with your wing. I may bug you for some wing cores if it flies. I want to build one with the Mubu II planform and you are there. No time to set up my foam cutter right now but did just get my vacuum pump back!! Go Yuri....
Feb 03, 2009, 07:58 PM
One Idiot is plenty...
Dbox's Avatar
Troy,I have got a set of cores and they are actually better then mine.
PM me if You want to challenge Yourself one more time.
Yuri.
Feb 05, 2009, 07:38 AM
Registered User
Paul.S's Avatar
Hello everone,

maybe it can help a bit:

Just in the moment im sitting infront of the Mubu you can see on the video and I take a goniometer (hope the translationprog did it right)

For the start the elevator flap hanging about 8. Maximum deflection is 32. With that it is possible to stall the wing when its sailing (with a little power it is easier, because the prop accelerate the air around the elevator only). So we reach almost the feeling a normal elevator... anyway, it is a different to fly this wing. But it is much easier to fly than the Multibumm at high lift.

For neutral speed, the elevator is -(1-2) degrees up. I think this little mistake comes from the point, the profil from the middle section has another zero-lift angel, as we expected. Max deflection is now 12. The turn is not very tight, but tight...

For landing, we change back to start, to get enough elevator.

Downpitch (elevator up) is everytime about -(7-8)... Its a pylonwing.

After about 15-20 starts I do myself, I will now put the CG about 3-5mm backwards. I will report.

Altough the elevator deflection is very high, the sailingperformance (landing) is quite good, compared to some Hotliners. We dont have much possibilities to compare jet.

Last time it was possible to stay a few minutes in altitude in thermal lift. Myself and some other around me have been ambrace to it.

Hope youll get success to

Paul
Last edited by Paul.S; Feb 05, 2009 at 10:19 AM.
Feb 05, 2009, 07:47 AM
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Paul.S's Avatar
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