The Fantastic p30 by Michael Woodhouse
The P30 class of rubber models has been popular in the USA for many years being a simple basic class that rewards the builder with a fine performance. The enthusiasm for this class has now spread into other countries including the UK. The most difficult part of a rubber model is the propeller, to overcome this issue the P30 class specifies an over the counter prop unit. This requirement to use only a standard propeller is the prime mover for the event.
Below is an extract from the BMFA rule book for 3.41 P.30 Rubber:
3.41.1 The Model
Maximum projected span............................................................ 30 inches
Maximum length of fuselage including propeller and any release D/T wires...... 30 inches
Minimum weight of model, less motor ....................................... 40 grams
The model shall have no timed moving surfaces apart from dethermaliser.
3.41.2 The Propeller
Only a commercial plastic propeller with a maximum diameter of 9.5 inches may be used. The hub may be modified to fit the shaft and for freewheeling purposes but not for folding. Plastic may be removed from the surface of one blade for balancing purposes only. The diameter, pitch and blade shape may not be altered.
3.41.3 The Motor
Maximum of 10 grams (lubricated) rubber motor, which must be enclosed within the fuselage.
Note that the rules in other countries may vary regarding minimum and rubber weights and other details, however the overall dimensions remain uncompromised.
Several P30 kits are already available from both the UK and overseas.
“Fantastic” is a new P30 kit from Turkey. I was given a pre-production kit at the European Free Flight Championships in Turkey for evaluation. I saw a couple of prototypes flown as well, in Turkey and they looked very good. Bearing in mind that the building instructions were in Turkish (kits will, in the future, include details in English) and this kit is one of the first off the production line, the initial opinion was that this was an excellent product. After construction of the model this view of quality still holds good.
On opening the box one views a set of very high quality laser cut parts, both balsa and plywood. A quality that would be hard to match let alone beat. There were some faults in the sizing of parts in the sample that I was given; however these have been fixed for the future sales production. The kit is comprehensive and all that is needed to complete the model is adhesive and dope.
One innovation is a rubber tension-controlled rudder. The rudder is pulled to the left when the tension of full turns is applied; as the rubber tension relaxes the rudder moves over to the right. The idea is to hold the rudder to the left to give a straight initial climb that gradually goes into a right hand spiral followed by a right hand glide. See trimming notes for prohibition of its use in competition. Another innovation is the asymmetric wing, the right hand inner panel being slightly longer, the idea being to help keep the inside wing up on the climb part of the flight.
Spencer Willis built the review sample. The only faults noted by Spencer were the wrong sizing of some parts. This fault has already been noted and will be corrected in the sales products. Spencer also noted the size of the D/T snuffer tube, a different size of fuse in Turkey? However this is not a real issue. The prop shaft was sloppy fit within the bush; Spencer replaced these with better fitting parts. The kit parts are being upgraded.
The construction of the model was straightforward and the building was soon completed. The model is of a standard “stick and tissue” construction. Many of the current PO30s kits available have a rolled tube or sheet box fuselage. The “Fantastic” is less usual in that the fuz. is a built up structure. This takes longer to build but is plenty strong enough for the model. Spencer covered the fuz. in lightweight silk. One suggestion, from the designer, to make the fuz. stiffer would be to replace the upright spacers with diagonals at the expense of less vertical spacers. This change would increase the amount of material used, which could be compensated for by reducing the width of the strip used for the diagonals. However in Spencer’s opinion the model as kitted is plenty strong enough.
The “Fantastic” is no lightweight and Spencer’s model weighed in at 45grammes. The addition of a viscous timer would have increased this weight. However, who apart from a few experts can get a P30 down to 40 grammes? Maybe the P30 rules need a change as after all this is supposed to be a class for novices?
Flying and trimming – from the designer
For the initial trim the advice from the designer is as follows:
· Set CG per plan and glue the pylon in place
· Add right tail tilt as per plan of 3mm.
· Add 2.5 degrees right side thrust
· Note that no down thrust is needed - Check and ensure that the thrust line is fixed at zero and leave it there
· With the auto rudder engaged, the rudder should be approximately set at 1.0 mm to the left
· When the auto rudder is released the rudder should be approximately 1.5mm to the right
Adjust the combination of right thrust and rudder, until a very slight arc to left during the power burst is achieved that is followed by a steep rolling spiral upwards to the right. During the power burst, the test models tended to go straight, without any looping tendency. If launched flat the model continued at that low angle. So launch the model at 60 degrees. The test models behaved like a models with VIT. The suggested reason for this phenomenon is that tail and wing sections are the same.
Flying and trimming to UK rules
In the UK no auto surfaces are allowed so trimming has been done with the auto rudder locked out. If you fly in a BMFA event remember that you will need to do this. If you fly the model for your own pleasure and enjoyment this will not be necessary so you can use the auto rudder system.
Spencer locked the rudder in the straight position. The trimming was straightforward using right thrust and rudder for the glide. The asymmetric wing (long right inner panel) obviated the need for wash-in to hold the inner wing up during the power turn. The longer wing does not appear to be effected by model speed, as does wash-in, making for a simple trimming exercise. The requirement to point the model into the power pattern was noted; the model will go where it was pointed.
A well designed and well presented kit model that can perform with and equal the best. Build it carefully and you will have a model that will live up to its name of “Fantastic”!
Cost and availability
The kit is available:
£35.00 plus shipping
Free Flight Supplies
12 Marston Lane
Michael J. Woodhouse January 2011