To be successful in an attempt of record is very exciting and rewarding but you can imagine that it's preceded by difficult moments. This page exhibits only the results, but if you are interested by the preparation of a record and the related human venture, you can browse or print the other pages in the menu >   I Records 

• Record with HBE_00

• Record with HBE_E

• Matching the records

• Future attempts

A non official attempt took place the 9th of June-1999 : a hover flight of 23 minutes 40 was operated on our platform with very calm weather conditions. The machine weighted 6940gr including 3800gr of batteries (2x32 NiCd cells of 2Ah). At this time the blades were in aluminum (non twisted blades) and rotor heads were of rigid type. The pitching axis was the only one to be gyro stabilized. Later on we became aware that this minimum stabilization would have not provided enough defense in turbulent atmosphere.

The record attempt with HBE_E was organized officially according to the FAI regulation with the active support of our club (La Croix du Sud) and of our federation (FFAM).. It took place the 8th of-July-2000 on the field of Perreux en Yvelines close to Rambouillet. Weather conditions were rain oriented and fortunately almost sunny and a bit windy during the attempt (around 18°C and a wind in the range 5 to 20km/h). The duration of 21 minutes 41 seconds can be considered as a result rather weak because to make sure there is no ground touch, the hover was higher than the habit.

HBE_E the 8th of July 2000

Both records were operated with the same battery cells, providing 1.8Ah. The main data are given in the table below :

= 138,24Wh or

= 8294,4Wminute

= 90,7Wh or

= 5442Wminute

= 345,6W

= 247,4W

= 48,8W/kg

= 50,3W/kg

Matching the performances is rather difficult. HBE_00 consumed a specific power of 48W/kg, so 3% less than HBE_E but they don't have the same <active mass over passive mass ratio> that is clearly in favor of HBE_00. In other words it is as if we force HBE_E to lift an additional passive mass. A simulation on HBE_E with a passive mass of 2066gr (2500/2066=1,21) proves that it compensates the loss of 3%. One should notice that also other parameters come up such as the size difference in favor of HBE_00, the disk load in favor of HBE_E, the pitch angle optimization.

One of the most obvious conclusions is that for a given aerodynamic configuration, the best <active mass over passive mass ratio> should be striven for.

It is difficult to investigate about theoretical aerodynamic limits but, in principle we estimate that we are not very far from that and if, in the F5C category, you know how to go down lower than 45W/kg (total consumption) we would be very excited to hear it !!! (do you believe to miracles?)

We plan two next attempts (we always speak of attempts because the result is never in the bag before the attempt) :

One attempt with HBE_E equipped  with Lithium-Ion rechargeable cells

The other with HBE_T

The attempt with HBE_T will raise big piloting problems because the duration to beat is  5 hours and 15 minutes and even if it's possible to be replaced by another pilot, the first hour must be done by the chief pilot. This is a very strong psychological constraint that was dominated by the present holder Mikhail Pruss, alone, during those five night hours. This self control forces our admiration...

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