Commission Regulation (EU) 2017/2400Show full title

Appendix 5 Air drag family for trucks

1. General

An air drag family is characterized by design and performance parameters. These shall be common to all vehicles within the family. The manufacturer may decide which vehicles belong to an air drag family as long as the membership criteria listed in paragraph 4 are respected. The air drag family shall be approved by the approval authority. The manufacturer shall provide to the approval authority the appropriate information relating to the air drag of the members of the air drag family.

2. Special cases

In some cases there may be interaction between parameters. This shall be taken into consideration to ensure that only vehicles with similar characteristics are included within the same air drag family. These cases shall be identified by the manufacturer and notified to the approval authority. It shall then be taken into account as a criterion for creating a new air drag family.

In addition to the parameters listed in paragraph 4, the manufacturer may introduce additional criteria allowing the definition of families of more restricted size.

3. All vehicles within a family get the same air drag value than the corresponding ‘parent vehicle’ of the family. This air drag value has to be measured on the parent vehicle according to the constant speed test procedure as described in section 3 of the main part of this Annex.

4. Parameter defining the air drag family:

4.1. Vehicles are allowed to be grouped within a family if the following criteria are fulfilled:

(a)

Same cabin width and body in white geometry up to B-pillar and above the heel point excluding the cab bottom (e.g. engine tunnel). All members of the family stay within a range of ± 10 mm to the parent vehicle.

(b)

Same roof height in vertical Z. All members of the family stay within a range of ± 10 mm to the parent vehicle.

(c)

Same height of cabin over frame. This criterion is fulfilled if the height difference of the cabins over frame stays within Z < 175mm.

The fulfillment of the family concept requirements shall be demonstrated by CAD (computer-aided design) data.

Figure 1 Family definition

4.2. An air drag family consist of testable members and vehicle configurations which can not be tested in accordance with this regulation.

4.3. Testable members of a family are vehicle configurations, which fulfil the installation requirements as defined in 3.3 in the main part of this Annex.

5. Choice of the air drag parent vehicle

5.1. The parent vehicle of each family shall be selected according to the following criteria:

5.2. The vehicle chassis shall fit to the dimensions of the standard body or semi-trailer as defined in Appendix 4 of this Annex.

5.3. All testable members of the family shall have an equal or lower air drag value than the value C_d · A_declared declared for the parent vehicle.

5.4. The applicant for a certificate shall be able to demonstrate that the selection of the parent vehicle meets the provisions as stated in 5.3 based on scientific methods e.g. CFD, wind tunnel results or good engineering practice. This provision applies for all vehicle variants which can be tested by the constant speed procedure as described in this Annex. Other vehicle configurations (e.g. vehicle heights not in accordance with the provisions in Appendix 4, wheel bases not compatible with the standard body dimensions of Appendix 5) shall get the same air drag value as the testable parent within the family without any further demonstration. As tires are considered as part of the measurement equipment, their influence shall be excluded in proving the worst case scenario.

5.5. Air drag values can be used for creation of families in other vehicle classes if the family criteria in accordance with point 5 of this Appendix are met based on the provisions given in Table 16.

Table 16

Provisions for transfer of air drag values to other vehicle classes

Vehicle group	Transfer formula	Remarks
1	Vehicle group 2 – 0,2 m2	Only allowed if value for related family in group 2 was measured
2	Vehicle group 3 – 0,2 m2	Only allowed if value for related family in group 3 was measured
3	Vehicle group 4 – 0,2 m2
4	No transfer allowed
5	No transfer allowed
9	Vehicle group 1,2,3,4 + 0,1 m2	Applicable group for transfer has to match with gross vehicle weight. Transfer of already transferred values allowed.
10	Vehicle group 1,2,3,5 + 0,1 m2
11	Vehicle group 9	Transfer of already transferred values allowed
12	Vehicle group 10	Transfer of already transferred values allowed
16	No transfer allowed	Only table value applicable