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Nov 05, 2012, 08:59 PM
Registered User

200mph Beevolution

Having had a couple of Beevo's I thought I would have a crack at making a fast one. The Beevo foam is pretty hard so I was going to just use the ribbon spars and then cover it with some 200g carbon, bagged elevons and wing tips. I know covering epp with carbon might seem like a waste of time but I had an M60 with a 100g fibreglass skin that held up really well.

I need to do the COG numbers to work out exact layup and lead required. At this stage I thought a target weight of 65oz based on a 3.25sqft wing area giving 20oz/sqft loading would be a good starting point although perhaps that is underbaking it a little with target speed of 200mph?

I have flirted with the idea of a balsa shear web but want to keep it straight forward so I actually get it finished. I welcome any suggestions/comments.
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Nov 05, 2012, 09:26 PM
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Daemon's Avatar
I have a suspicion that a high wing loading Beevo will fly quite poorly.
The Beevo seems to not like high angles of attack (slows down quickly when you
push it around or in rough DS air) and I think the weight will exasperate that problem.

Nov 05, 2012, 09:35 PM
Registered User
Oh, that is not such great news, thanks for your response though! I have done 100mph with a light beevo ~700g with a 500g bit of lead on the belly. I was hoping for more of the same, errr, that was about the extent of my consideration of the matter.

Reckon I should flag whole thing? Not sure what I would do with this plane if it won't really perform.
Nov 05, 2012, 09:39 PM
Remember... Fly for fun!
Rob. Its an EPP model
Nov 05, 2012, 10:02 PM
Registered User
Yes, it is. Are you thinking the crunchy skin on the soft core? Or just that it isn't likely to be accurate enough in terms of profile to be worth laying up? Both are valid I guess but what am I going to do with it anyway?
Nov 05, 2012, 11:58 PM
Remember... Fly for fun!
EPP and bagging don't usually mix well.

A good Beevo Foam build should be almost capable of 200
Nov 06, 2012, 01:05 AM
Registered User

How to know your an idiot....

Errr, ignoring the advice of two of the most knowledgeable DS guys on earth and doing it anyway. Honestly, I have a bit of carbon kicking about and have always wanted to do this. Results be damned, it can go on the wall if it isn't fast.

I will post results, good and bad.

Let's start with bad. Gorilla glue is my go to for pretty much everything. Dampened and put the cores and internal spar together last night with it. I masking tape the seams to keep the glue from foaming too much and limit clean up. Came back 4 hours later and it looked exactly as I had anticipated, just the tape to remove. Lo and behold the PU can up with the tape. It wouldn't happen with cut foam but the molded EPP is quite different. I doubt it is just the release agent on the mold, more the lack of surface texture on the molded surface. Either way I was able to pull the cores apart and peel off the PU, repeated with contact adhesive, Ados F2 from a can. Left to tack for 5 mins and back together like a rock.

The molds seems slightly misaligned with the leading edge having a weird overbite lip. I went to remove it with a razor plane but found sanding it back with 80 grit went much better.

And using your instead of you're
Nov 06, 2012, 02:56 AM
Registered User

Couple of pics

The TE was quite wavy out of the mold. I haven't seen that on my other bees but before putting any spars in I thought I would put that issue to bed. TE roughed up with sand paper as was the 1mm x 6mm spars which fit pretty much perfectly. It is epoxied on while the TE is clamped down. Due to the geometry I have to do these one at a time.

It seems wise I don't use the front battery mount as it would be better occupied with lead. I have made a 5 cell Nimh pack and glassed it to keep it rigid.

Excuse the photos. I have only finished building the garage recently and still have to put in a few more lights.
Nov 06, 2012, 05:46 AM
Registered User
The other TE is now clamped with carbon spar. I honestly am stunned by how effective the standard Beevo ribbon wing spar's are. I am thinking about using a few of these to increase core crush resistance. I have a ton of these ribbons here so was thinking of adding 4 or five top and bottom. They add no weight in the scheme of things and if they decrease the crush effect it is weight well used.

It looks like 400g carbon is the covering of choice in first past analysis. I have this as 2 layers of unis stitched together orthogonally for 400g cloth weight or 2 x layers of 200g bidirectional weave. Need to do geometric analysis as in the perfect case I would use both. It keeps coming back to the lead required in the front limiting the layup as in the first past as is seems equal to almost 60% of the skin weight.
Nov 06, 2012, 06:25 AM
Registered User
Sleedo's Avatar
I like this approach (for you), I have always wanted to see how this would work out but never got up the courage to try it myself. Big fan of my Beevo that is covered in 1 1/3 layer of 10 mil NS (1 full layer and then a layer 1/3 back from the LE on top of that. Nearly indestructible DS pioneer ideal for learning how and where to DS on the East Coast USA.

please continue..
Nov 06, 2012, 06:27 AM
C'mon more Energy
Swoopdown's Avatar
Go get em Rob. Can't wait to see how it turns out.
Nov 06, 2012, 08:32 AM
Objects in mirror are losing
1000MPH's Avatar
Looks cool Reaper Rob. IMO, bagging in carbon isn't needed for a 200mph capable BeEvo.
Are you going with a full trailing edge or stock style elevon config?
Full trailing edge on my 70oz Bee seems to require a more forward CG for stability.
Especially over 150-160.
At 70oz it's a bit of a Pig, 40oz is my favorite for the Bee, YMMV with the BeEvo.
Nov 06, 2012, 10:50 AM
More like crunchman....
dsman's Avatar
Using this opportunity to ask the IDs of the pilots & the specs of the 3 planes in the now infamous 'furball' video at BSP.

Recall a JW, M60 & (?) flying wing.
Nov 06, 2012, 12:23 PM
Registered User
jonoashton's Avatar

I bagged a Bee2 and was surprised just how much the EPP compressed. It compressed to a point that the standard servos did not fit very well any more and the spar is a noticeable ridge. It was an old wrecked one that I fixed up and just bagged it as an experiment to see how it went.
I would recommend that you use a low pressure in the bag, perhaps between 6 and 10 inches of mercury at a guess as I think I used more like 12 – 14 inches and it was too much.
That said, it still flies pretty good and I have DS’ed it in light air (it is about 800 grams) numerous times

Nov 06, 2012, 03:39 PM
608 km/h!
josh18's Avatar
Hey Rob, Why not do a bagged blue foam reaper instead?, especially with that carbon it would be unreal! At least if you change your mind you can still cover your beevo in 10mil laminating film for something that'd be nearly as good as a bagged one.
Keep us posted either way

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