....Ever seen a Jumbo Jet take off, stop in mid air, then climb away BACKWARDS if the answer is NO you'd better take a good look at this one!HANGAR AND STRIP REPORT by Dave Burns
Way back in issue #127, January '95, I completed a review of the Sig Fazer Funfly model. At the time this model was probably considered the starting point for the mass produced class of funfly model. In the meantime, we have seen a virtual explosion of available kits and plans for various types in the funfly category. Some have been interesting, others a mere shadow of a golf stick with wings. Not to be remiss in this area, the design team at AIRBORNE magazine have been busy putting crayon to butchers paper, and have come up with there own range of funfly models, based around recognisable subjects. The first to commit acts in matters aeronautique is the 747SP - (Special Profile) Jumbo Jet.
This is one of the easiest models to build, even to relative newcomers. It is very inexpensive, and gives a great deal of return for a minimal cost. Being very aerobatic, but also easy to fly, should prove popular with everyone.
The plan comes on a single dyeline sheet, with clear line work, and all parts defined as to material and dimensions. The model is designed for a .40 to .46 size engine, and four function radio.
The fuse is of simple stick construction, overlayed with 1.5mm sheeting, for stiffening. The profile fuse parts consist of 9.5mm square stock and forward fuse section from 9.5mm sheet. The timber engine bearers are built into the forward fuse section, and require the builder to set the spacing to suit the engine type he will be using. This is the only major change from the build sequence, and the fuse can be completely built following the plans layout. Around the tail position you will have to make allowance for the insertion of fin and stab in the build-up fuse.
Using aliphatic glue throughout, except for engine bearers, allows you to achieve a nicely sanded finish prior to covering. After all the initial parts and strips had been cut to size, the actual build time for the fuse should be one evenings work, and that includes drying time.....
The wing material is 1.5mm ribs, 6.5mm sq. spars, 9.5mm strip and 1.5mm sheeting. The aerofoil is shown full size on the plan and only requires the builder to cut out 14 ribs from the 1.5 sheet, then pin all the ribs together and give a uniform sanding all over. Begin layup using traditional rib, spar and sheeting techniques (D-tube). If you want to make the wing construction a little easier, you can include temporary rib tabs which will assist in keeping your wing layup straight. The wing is a rather large affair due to its wing chord, but the advantage here is that the entire wing build should only be on the bench for two nights..... YES, it IS that simple and easy.
Be aware that the position for the radio gear is purely a suggested positioning, and the individual may have to make changes to suit type and style being used.
Due to ALL the R/C gear fitting inside the wing root area, the builder will have to make hatches so that the gear is accessible for service or adjustment... again suggested methods are shown on the plan, but we all have our own modus operandi in this respect, so study first, cut second.
The rudder, stabiliser and elevators are simple stick construction from 9.5mm strip and sheet, and pose no problem in there build up.
The wing is mated to the fuse by sliding through a profile cut in the fuse thickness. Take your time here to achieve a nice close fit, and when seated properly, achieving a 90 degree fit to the fuse side, then go ahead and EPOXY into place. While this is setting up, you can manufacture the simplified landing gear from 3mm aluminium strip and lightweight wheels.
When wing epoxy is setup, and with model still locked to building board, then go ahead and EPOXY in the stabiliser. The fin can then be fitted using aliphatic and when completed give the model and all over final sand.
Our prototype was covered in red and white Monokote, which gives a high lustrous finish and is easy to use. The simulated windows were cut from black Solartrim using a slightly flattened pipe with a ground cutting each. All the control surfaces were covered separately to the model. then hinged using Great Planes cyano hinges ... these worked great and proved super flexible.
The tail skid is shown as a bound wire assy, but if you wanted to you could fit a tailwheel, but we have found this totally unnecessary, as the tail is NEVER on the ground long enough. In actual fact, the skid is used as a balancing point only.
We optioned the 747 with a tried and true HP 40, and a COOPER super-quiet muffler. Another first choice motor would be the new O.S 40 BLUE motor.
Radio system used was a FUTABA 8 channel computer system, with HI_TEC servos. We used the computer radio so that we could start fiddling with the mixes available . ... but this is NOT required as standard, and any good 4 channel system will suffice.
FLYING THE SLIMMERS JUMBO:
This is where it all comes together (we hope), and with lots of admiring glances, and some in shocked disbelief at such sacrilege, we completed the preflight checks, and progressed to putting air under our wheels.
The takeoff is simple, straight and uncomplicated - well it had to be.... the rollout was only approx TWO METRE. Vertical performance is great, and the combination of this model and a .40 size motor seems about spot on.
Progressing to slow flying, fast beatups, which in reality is only marginally faster than slow flight, big loops or very tight vertical and horizontal eights .... and all this in the space of a control line circle...... joined by IAN BOYD's Gee Bee Whizz in the air, everyone else landed to watch the spectacle of two fun-fly models trying very hard to tie themselves into knots.... WHAT GREAT FUN, FOR MINIMAL DOLLARS.
A new manoeuvre is discovered - fly forward into a five knot breeze. Ease the power back while slowly adding up elevator. Keep doing this until the model almost stops in midair ... add two clicks of power ON, while pulling the elevator stick all the way back ... if you get the timing and settings right (its takes a little practice), your model will now be FLYING BACKWARDS, AND CLIMBING. Read this again and imagine the model position... it looks weird. Next time we are going to try this inverted........ Does all this sound like a lot of fun ... YOU BET.
Now you see, there is something good that comes out of Victoria, besides the Hume Highway, of course.
JUMBO-JET 747 SP (SPECIAL PROFILE) FUN FLYWingspan: 1.2 metre
Length: 1.1 metre
4 channel radio control required
Jumbo Jet plans are available from:
Other fun flies available soon.