Cheetah

I have just ordered one of these.

For no good reason other than someone on another site suggested it was unsuitable to convert to RC.
The reasons given was its wing halves just plug in to the fuselage so would need extra reinforcing to carry extra weight and the fuselage is solid so would have to be 'excavated' to create internal space.
My reason for doing it, apart from ego, it that it is the same size as the Lidl glider

And it is cheaper too.
It is coming from Taipei in Taiwan so it could take a while.
By the wonders of Google street view the senders business address is somewhere in this building. :ohmy:

Note the inevitable McDonalds right next door.

Interesting. I envisage some lessons in creative foam carving on the horizon ! :lol:

I've bought about 10 of those in total for the grandkids to chuck about, they're only a couple of quid each on ebay. A mate of mine bought himself and me one ages ago but he paid top whack buying them from a UK model shop. One of the kids ended up with mine and had hours of fun with it ..... so obviously the whole brood wanted one then.
I have heard of someone doing an RC conversion on one and from what I remember I think it's perfectly possible.
The models are made from EPP and are crash proof, just glue the wings in place with epoxy and get cutting away at the fuz. :lol:

Pol

Pol
"just glue the wings in place with epoxy and get cutting away at the fuz"
Yes but that would be the easy option.
Unlike the Lidl the Cheetah actually looks quite like a modern glider but with a reduced wing span.
As the wings are already in two parts it seems logical to insert a new centre section to increase the span by about 1/3.
This process has the advantage that provided the new centre section is designed appropriately the new wing will be able to carry more weight with the same wing loading yet keep the stress on the outer wing panels the same.

This is exactly what was done on the AN225. Although 50% heavier than the AN124 it uses the same wings but with a new centre section that adds nearly 50% more wing area (and 2 more engines).

It is just as well that in my case "Time is not money". :woohoo:

At last the Cheetah has arrived.
This is roughly how I expect the wing span to end up.

It is quite well moulded although of course nothing is particularly true and square!
A banana fuselage.:ohmy:

And the fin has a big kink in it too.
The wings are almost identical in shape.
The canopy has two large steel balls in as ballast.

Together they weigh 32 g.

So is this chuck glider worth trying to convert to a RC motor glider?
Probably not - which is a good enough reason for me to try.

I hope you thoroughly disinfected it first! [badass]

Ha!
No worries. It has taken 3 weeks to get here and the virus life on even the most benign surface is no longer than 3 days.

Just for info the Cheetah 'as is' weighs 119 g. The ballast balls weigh 32 g so the starting point is 87 g.

Started to think about building the new centre section for the Cheetah.
I estimate a 2mm Depron skin alone will be strong enough with no specific reinforcement so decided to print the ribs and the shear web between them.Two very light pieces just repeated as many times as required to achieve the span.

Together it weighs 0.75 g. There will be 9 units in the complete wing.
Although primarily a shear web when all are glued together the it will act as a significant 'spar' in its own right.

Each segment is glued in turn onto the Depron lower skin.

It all just an experiment but then with Boris's latest edicts I have nothing else to do! :woohoo:

The RH wing glued to the centre section with the trailing edge extensions added and the aileron cut out.

The TE extensions made from 2 mm Depron top and bottom but sanded in their inner surfaces to give a fine trailing edge.
A 'before and after' trailing edge comparison.

Although the Cheetah TE at 4 mm is significantly thinner than the 6+ mm on the Lidl I still think a proper trailing edge improves the glide performance and the modest increase in wing area it creates can be helpful, particularly for the fixed fin and elevators.
Still waiting for the 2 g aileron servos.

The wing showing the full span with the fuselage and tail plane in roughly the right relationship.

The tail plane and fin will actually have about 20% more area when their trailing edge extensions are added.
I have a suitable small 55 W motor (it should give over 100w/lb ) but the light 5x3 folding prop I need is of course out of stock at HobbyKing and with no ETA either!
Next tricky job is fitting the aileron servos. They will have to be wired up before the centre section skin can be completed.

With the first servo 'buried' in the wing a test of the LH aileron.

Note the 'printed' surface mounted aileron horn.

It has taken most of the day!
Now to do the same on the other side.

Couple of questions Q. I see there is no mechanical adjustment on the push-rod, so I presume you do all your trimming in the TX ? Also what's to stop it coming out of the horn ?

An 'O' of heat-shrink tubing? (once you have the throws something like correct).

Eric wrote: An 'O' of heat-shrink tubing? (once you have the throws something like correct).

Sounds like a bodge to me, a quick link (and lock nut) is the way to Go, no control= no model

I think, 'add lightness' is Simons watch word! Even a blob of thick glue would do the trick!