Finished destructive flight tests... el Cheapo update!

[AJCoholic]

Well, after many flights (>30?) and many crashes I finally had one that will ground el 'Cheapo for a bit...

For those unaware, my el 'Cheapo was an attempt at a cheap, good flying fun fly plane that is a hybrid of foam wing and coroplast fuse and tail. I have had many flights on it, and really have wrung the snot out of it. It has survived many crashes unscathed, and also some with minor repair.

The wing was foam core and reinforced with carbon fibre tow (top and bottom) and then covered with epoxy and brown kraft paper.

On my last flight I pulled out of a dive (full trottle) and leveled out, after a few hundered feet of level flight one wing panel departed and a second later the second one left too! Exciting to say the least!

Becuase I was flying paralled to the runway and out about 100feet in front of the pilot line at no time was anyone in danger. The plane went in, but no damage to the fuse, tail, or my Irvine 53 other than a broken prop.

Upon inspection, it seems the lower carbon tow/epoxy spar broke and the upper one stayed intact.

el 'Cheapo MKII will see a reinforced centre section with a few more strands of CF.

[AJCoholic]

more...

[scaleguy]

Andrew,

How did you get jim McIntyre's triplane away from him?

I see it skewered on a pole in the top left hand corner of the first picture! :yikes: :lol: :lol: :lol:

[Nuker]

Hey Andrew,

do you folks fly from behind that fence or do you move in front?

Just curious about your setup

Bob

[JimMoss]

That's where the other members dive for cover when Andrew is flying! :wink:

Jim Moss :)

[AJCoholic]

Nuker,
Thats the Sudbury Model Aircraft Club field NOT my field (TARMAC, where we have a fence both in front of the spectators, the pitts AND the pilots! Yes, we have three barriers and its a safe field but we also have the room.

We stood in front of that fence and there is no barrier bewteen the pilots stations and the runway, but the runway is a wide one and a ways out.

Jim, I was trying hard to beat this plane up... finally succeeded! ;)

On my 2nd to last flight I was talking to Jim Bisson Jr. while rolling inverted on the runway and for a split second lost it, and forced it (ditch) down as not to give it even a chance to get near the fence. It bounced hard enough nose down to break my muffler, then came down hard on the tail... a "normal balsa" model would have been TOAST! But after a few minutes the el "Cheapo was back in the air, only to fold the wing.

I am surprised the carbon fibre tow broke, but hey thats how we learn.

I will build #2 this week, but allready know what I will change (simpler and stronger) and enlarge the fuse profile and tail feathers a wee bit too.

I'm sold on this type of plane for fun flying. If I had been flying a balsa/covered plane like my faser I would have wasted 4 or 5 of them easily in what the el 'Cheapo went through. Cartwheels, full power inverted into the field, landing on the tail, forced ditch landing, etc etc... a TOUGH plane!

[AJCoholic]

Andrew,

How did you get jim McIntyre's triplane away from him?

I see it skewered on a pole in the top left hand corner of the first picture! :yikes: :lol: :lol: :lol:

Jim, dont get me into more trouble than I allready am in... ;)

The winds were blowing pretty good (like in Tillsonburg) but the funny thing was they were changing the flight direction so often since the wind changed dorection allmost every 1/2 hour! :)

[nony]

.




MEMO FROM ENGINEERING OFFICE:

The attached NASA findings conclude that Carbon fibre TOW over foam in the presence of ultra violet light (such as sunlight) will fail explosively under high stress.

While some products with this configuration may have reached the market place, the risk is absolutely minimal. Should there be any inquiries from customers or the media, please assure them that all products have been independently tested to standards far in excess of epected useage, Due to factors beyond our control, this assurance is not valid in the Kirkland Lake area, and if there are any inquiries from this area - DENY EVERYTHING !


Signed,

Fing R. Pointer

Chief Engineer.


:D :D :D :D

[AJCoholic]

Now that I think of it, just before my last flight I remember seeing someone running away from the plane with a sharp knife and yelling something about "those hideous colors" and "that evil plane must be destroyed"...

:yikes:

I thought they were talking about this plane that was parked nearby! :shock:


(totally just joking whoever owns this magnificant plane.... :) )

[Vulcan1]

Andrew I thought you were flying a spad now. Just Kidding But I had a minor incident on Sunday out here. There is a new guy from Sask. here who hadn't flown for 2 years so I went out and flew my modifided scat cat with him and to help. I had 2 flights and he had 4 with a little help mostly landing. Then the new RCMP corporal shows up and he fly's too. Same problem (hasn't flown for a while) so I go to take off and wore my apc down on the pavement and lost my gear. Haven't done that for a long time. These guys will probably be on this site soon so keep them happy like you did for me.
Also I have to take some pics of were we fly. But all you will get is 75' x 500 yds. of WW2 pavement and wheat crop. I checked with the nearest house who has 2 boys if we bothered them. His comment was when were you out and let me bring my kids over. I had been out doing the usual ldg.and horsing around for 3 days and he didn't know I was there. We don't have a fence or anything but you can dive behind your car or your buddies.
I told him Sunday to park on the west side of me because if he was going to hit something it may as well be his vehicle.
Got to build my SPAD so have a good day.John

[Warbird_ace]

There was an article in the July Model Airplane News about that very triplane being repainted. Interesting

[PurgatorY]

Andrew

This was (is) a very common technique we used to make spars in foam wings for our pattern models.

The spar is oriented in the foam so that the CF acts like an I-beam. All you need to do is router a 1/4x1/4 slot in the wing and glue in the spar. They are super light, and very strong.

I have went as far as only cutting a slit in the foam and just gluing in the CF laminate but its more work (works just as good).

I dont know how you had the tow oriented in the wing, but tow is very heavy and unless designed properly wont provide much strength. Just laying it on top of the wing gives a little more strength but nothing even close to this type of spar.

Anyways here is a picture.

[AJCoholic]

Chad,
I have used a laminated balsa/cf/balsa spar in quite a few planes that had a wood spar. On the el 'Cheapo #1 I just ran some tow under the paper/epoxy covering full span top and bottom, just like when I make a smaller 1/2A model with a foam wing you use some FG reinforced packing tape for a "spar".

The wing is /was remakably strong for what it was, but obviously not enough for repeated punishing flights and crashes.

In the MKII wing which I have allready started, I cut a 1/8" wide groove allmost the full depth of the wing 1/3 back from the LE into which I glued a 1/8" by 1-7/8" wide strip of aircraft birch ply. THAT is strong enough, but on top of that I am gluing a .007 by 1/4" strip of CF twice on the top and twice on the bottom. Its light and I have a bunch so I will just use it.

I cant see this wing breaking, unless it hits the ground hard... should not fold this time.. :)

I am also making the new fuse from foam core/laminated coroplast onto both sides with CF under neath to stiffen the fuse up.

Flight tests on "el 'Cheap GRANDE!" to begin hopefully this weekend :D