About 8 years ago or so I designed a small electric sports model for low-cost gear and minimal build time. Now, I’ve brought it up-to-date with a FliteTest style reboot in our favorite foam board…
Crash-E Sports Trainer
The Crash-E was named as such because of the strong belief I had that it wouldn’t last past the maiden flight.
Built from balsa and ply over a couple of evenings the Crash-E used the cheapest electric equipment available at the time. At only a 28 inch span it was small enough and light enough to chuck in the back of the car and throw just about anywhere.
Imagine my surprise then when it flew so well that the hand-drawn plans were picked up and published by a UK modelling magazine.
A couple of weeks back I pulled the original plans out and took another look. Using foam board and a Flite Test style folded wing and fuselage it certainly looked possible to recreate the Crash-E for a new generation.
Designing the Crash-E V2
It was easy enough to transfer the measurements to Sketchup although it soon became apparent that foam board being thicker than the original balsa was going to require an enlargement of the design.
The first draft went to 150% but a preliminary export of the wing showed that it was going to be far too big. I eventually pulled it back to 125% and got around a 36″ span.
The design in foam board followed some fairly normal Flite Test style conventions with a folded wing and folded fuselage. I replicated the under-cambered wingtips from the FT Spitfire and Simple Soarer as a way of creating a stable airfoil and preventing tip stalls.
I printed and cut the wings first. The whole thing was over in the blink of an eye…
The one piece wing has a full width spar with the aileron servos located at the edge of the bottom plate and connected via a Y harness that exits through hole in the center of the wing.
Fuselage
The fuselage didn’t take much more time than the wing. The hardest part was cutting the curves around the nose!
The original had a central “box” that gave rigidity to the fuselage. I replicated this in foam board to give a double wall to the central fuselage and also extra surface area for the nifty little CNC cut firewall I had made.
Both the main fuselage and central box are an “A” style fold – that is the sides come up and over the base. Everything else simply sticks to or slots into this main structure.
Fitting Out
There’s plenty of room inside the Crash-E so you can spread your components around. The elevator servo was hot-glued to the side of the inner box and a wire/carbon pushrod run out through the rear of the fuselage to the control horn. The ESC was similarly stuck to a wall as was the Rx. This leaves plenty of room on the floor to Velcro in a LiPo.
For power I used a spare NTM 2826/1100kv outrunner and 30A ESC on 3S 2200mah cells. The motor turned out to be a bit short for the nose so instead of cutting the foam down I used some 10mm spacers to move it forward.
Ready to go then…
With everything ready to go the total airframe (including LiPo) came in at around 620g. The motor with a 9 inch slowfly prop produces more than 1:1 thrust so it’s all looking promising.
Of course, I’m writing all this before the maiden flight so it could all go horribly wrong…
It flies!
Just like it’s predecessor I was pleasantly surprised by how the Crash-E flew. It’s no pattern ship and the smaller control surfaces and lack of rudder means it will never fly 3D. What it is though is jolly good, worry free fun…
The NTM2826/1100kv puts out more than enough power and after probably a good 8 or 9 minutes of trimming and filming for the video I still had only used 950mah out of the 2200mah pack so duration is pretty awesome.
The Crash-E is nice and fast but can be slowed right up due to the low weight. The stall is pretty much non-existent but inverted flight does require a bit of power and a thumb load of forward stick to keep the nose up.
So what are you waiting for?
The Crash-E is a great little model for anyone looking for a low-cost, low-stress bank n’ yank sport aerobat. Construction is about as easy as it gets and you still end up with an airframe that can take a knock or two.
Of course, it would be easier to build if you had some plans so here they are…
NOTE:
A lot of the fold lines in the fuselage and wing are marked red for a 50% score cut. This is because it is impossible to “crease” our heavy Australian board so we need ot cut it to bend it. If you are in the US and using lighter “Readiboard” you may get away with just a “rub and crease” on these lines.
Enjoy!
This article is replicated from the original over at www.red20rc.org
If you get time, go and take a look at all the other stuff I'm doing over there!
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I think it will be an great "next" plane, after the "FT Flyer", for learning the use of ailerons.
To me, the "Bloody Wonder" seems too twitchy for a first Bank-n-Yank plane. This one seems much more stable and is no more difficult to build than the BW.
Thanks for sharing this design.
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It is a nice plane to fly and can be thrown together in no time. It helps to build confidence as there is very little effort goes into it so you don't have to worry about breaking it!
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Thanks, LooseBruce
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There is no rudder although I did do a 36" version some years ago in balsa with a rudder. It would be quite easy to fit one with a few mods to the design.
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For what it is I'm really pleased with the flight performance. The nice thing is that beause it is so simple you don't have to be scared to fly it hard and try things like low passes and loops and rolls. Just watch the speed and elevator when inverted as that high mounted flat bottom wing means the nose will drop!
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The original was made over here in Australia where we can get FB in 40"x30" sheets so it wasn't a problem. If the largest available is 30" then it will be necessary to split the wing in the middle and then join the two panels with glue and tape the same as other FT builds.
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This was actually a copy of a balsa model I designed some years ago. In fact there is an article somewhere here in FT by someone who was building the original.
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Right, back...
I've got about 10mm each way on the elevator and 13-15mm each way on the ailerons.
Hope that helps and good luck :)
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