Prelim

F1 Evo - Preliminary Performance Assessment


Team Rocket, in collaboration with HPAI, has begun the flight test program on the F1 Evo
(evolutionary new wing design).

The new airfoil is an MS(1)-313. This airfoil series, along with the LS(1)-xxx series, and the NLF series, were developed by NASA in the seventies. Their testing shows a potential 20% decrease in wing drag through use of these air foils. A secondary positive side of these air foils is that surface degradation through rain, or insect leading edge contamination, does not cause a significant problems: a contaminated airfoil still provides drag equal to our current air foil, the NACA 23013.5.


As with any other experimental modifications, one change begets multiple others. Of course, who can understand all associated changes which will be required, until some initial evaluation and testing is launched. And, as it turns out, we have some further refinements to develop in order to complete the testing with a resulting marketable product.

Early test flight results indicate a slight cruise airspeed increase, and an impressive stall speed decrease. Computer modelling predicts a potential 5+% cruise speed increase, and preliminary flight testing confirms this.

The cruise speed measurements are not final, by any means. It turns out that the flaps will not fully retract – they remain extended about 3-4 deg. This adds some amount of drag due to the flap extension, but it also introduces a significant amount of trim drag. Previous adjustments to flying F1s showed a 5-7KT increase in speed when the horizontal tail is properly adjusted, and it may be that our cruise speed is affected in a similar manner. A new set of flaps, with re-designed bracketry, will be installed, and the horizontal tail will be adjusted to match the resulting angle of incidence.

In addition, the flaps are a slotted design, and the associated large hinge brackets will need to be faired in.


NASA testing of these air foils also indicated possible high control system pressures, due to the heavy aft camber associated with these air foils. High pressures are less of a consideration in aircraft configured for cruising flight, but high control system pressures are generally unacceptable for aircraft whose missions include manoeuvring flight. NASA addressed these high control system pressures by equipping their test aircraft with spoilers instead of ailerons. From a marketing perspective, adding spoilers to our aircraft is not an option. As a first step, the control system pressures will need to be addressed by internal system ratio adjustments, and servo assist tabs as a secondary option.

We expect the new parts to be shipped to us and installed for further testing in early February. We will post another update after the second round of test flights.

Observations:
Preliminary stall speed ~50mph, 43.5KT
Preliminary cruise speed increase +2KT
Take off distance approximately -15%

Open Items (to be addressed):
Control system pressures – adjust internal ratios
Flaps do not fully retract – fabricate and install new flaps
Install root fairings
Install wing tips
Install flap bracket fairings
Complete flap actuator redesign
Paint new wings