Forwarded from the bounce bin. Message is from
"Jerry Davis" <lts@avnet.co.uk>
[Jerry posted the message in HTML and the bouncing process has deformatted it,
so if you want to study the figures you might want to rearrange them to taste -
John]
*********************************************************************
I have developed my numbers a little further. I have always guessed my
power by using the actual fuel consumption and determining what % it was
of the max. That is If I was burning about 11 litres an hour I
considered that I was using 50% power. Now looking at the Rotax book
values this turns out to be surprisingly close to what Rotax say. Below
is a table of Aircraft speed / percentage power / hp / Rotax official
consumption / my guestimation of consumption. Given a max speed of 137
kts I quite agree that 65% power would give around 120 kts but at 15
litre per hour and not 10 litres per hour. I have compared the figures I
get on my own aircraft and they match my calculated predictions within a
couple of kts and within 1 litre per hour. I get around 152 kts TAS at
5500 full throttle and 130 kts TAS using 14.5 litres per hour both at
5000 ft. If anybody wishes to claim their Europa does 120 kts at 10
litres per hour then I challenge them to fly together with me with a
measured 20 litres of fuel in our tanks (no reserve) and we'll see who
drops out of the sky first.That reminds me I should go and do those
little jobs to speed up my plane and get off this silly computer.
Speed for % power settings is given by - 100% power speed * (% power)
0.333
kts
% power
hp
Rotax consumption
calculated consumption
137
100%
80
22.5
22.5
135
95%
76
21
21
132
90%
72
20
20
130
85%
68
19
19
127
80%
64
18
18
124
75%
60
17
17
122
70%
56
16
16
119
65%
52
15
15
116
60%
48
14
14
112
55%
44
13
12
109
50%
40
12
11
105
45%
36
11
10
101
40%
32
10
9
97
35%
28
9
8
92
30%
24
8
7
86
25%
20
7
6
80
20%
16
6
4
My Aircraft at 5000' on a summer's day
kts
% power
hp
Rotax consumption
calculated consumption
154
100%
80
22.5
22.5
151
95%
76
21
21
149
90%
72
20
20
146
85%
68
19
19
143
80%
64
18
18
140
75%
60
17
17
137
70%
56
16
16
133
65%
52
15
15
130
60%
48
14
14
126
55%
44
13
12
122
50%
40
12
11
118
45%
36
11
10
114
40%
32
10
9
109
35%
28
9
8
103
30%
24
8
7
97
25%
20
7
6
90
20%
16
6
4
There's no magic in maths just enlightenment.
Jerry
LTS@avnet.co.uk
http://www.avnet.co.uk/touchdown
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