Performance: Listet Values vs Real Data

[Sam the Swiss]

Yesterday I had the chance to visit Aero 2018 in Friedrichshafen. I even did see Dan Johnson! Like always there were a lot of new shiny planes on display, and then there were the performance sheets, some with numbers that seems reasonable, some with numbers too good to be true.

 

I know this phenomenon from reading, especially with aircraft that haven't flown at all so far, or are only a few flying hors old. As I am interested in building for example a Savannah S (well, my family does not agree yet), I would like to ask you weather you can write about the performance numbers you obtain with your Savannah. For example the advertised stall speed dirty icp gives did not change when MTOW changed form 472.5 kg to 600 kg.

 

So: What are the numbers you get?

 

For example stall speed dirty or clean at what weight, cruise speed at what rpm, take off roll and landing roll under which conditions? And also your empty weight with what equipment (e.g. lang range tanks or not).

 

That would be very interesting for me, thanks in advance!

 

Sam

 

 

[Neil_S]

Hi Sam,

 

OK - I'll start off with data from my Savvy S (from memory).

 

Empty weight about 310 kg - I have long range tanks, dual brakes, centre stick, adjustable seats, transponder, Garmin Aera 500, manual flaps, electric trim....

 

I usually fly solo, and I weigh about 60kg. With full tanks, and about 7kg of stuff in the baggage my take-off weight is around 470-480 kg.

 

So my figures when solo are usually closer to the old 450kg ones in the POH rather than the 600kg ones.

 

The stall speed gets hard to measure when I fly straight and just slow up as the angle of the pitot is high and not really reading accurately, but with full flap I see it around 25 kts. When clean it is around 30kts, but same issue with pitot at high AoA. (Book figures for 600kg are 30kts and 35kts respectively).

 

I cruise at around 4800-5000 rpm (100hp ULS), and my speed is around 82-83 IAS. I flight plan on 90 kts TAS, with cruise altitude usually over 4000ft AMSL, and over 3 years I have found that to be largely accurate.

 

I get about 15 litres per hour with 98 octane MOGAS (POH figure is 18.5). This gives me an endurance of 8 hours + reserve, which is well past my bladder endurance...

 

I haven't really measured my take-off roll as it varies with wind, surface, etc - but it would usually be less than 200m, and my rate of climb solo is usually 800-1000fpm as the flap extension speed is 60kts so I have to keep the nose angle high enough to avoid exceeding this. I usually climb out at 55kts, and I am frequently at circuit height before turning crosswind.

 

Landing distance is also usually less than 200m or so - I do not try to land short most of the time as it puts stress on the u/c to do this, and as my home field has 1200m of runway I really don't have to! Much shorter landings are definitely possible. Just search Youtube for videos of Savannahs doing short landings - there are many!

 

BTW - see if you can get Revision 6 or later of the POH as that has figures for both 450kg and 600kg MTOW.

 

I hope this helps. I have certainly been happy with my Savannah since I bought it, and there are many Savannah owners/builders in Australia who I think feel the same way.

 

Let me know if there are any other figures you would like, and I will try to supply them from my experience.

 

Good luck with convincing your family!!

 

Regards,

 

Neil

 

 

[Sam the Swiss]

Thank you Neil, interesting data. If anyone has the Revision 6 POH that would be interesting, too. But your real life data are even more interesting.

 

Sam

 

 

[g2omer]

Hi, my savannah vg : weight 680

 

Cruise at 5000 : 95 mph

 

Max cruise : around 105 mph

 

No long range tank

 

Fuel burn 15.5 l/h

 

912 uls

 

Mtow 1232

 

 

[MajorTom]

Hi Sam,

 

the Savannah is a good plane to built. Flight data are aviable in some weeks, because I'm just about to start test flights.

 

If you are interested in building, you might want to check www.savannah-blog.de

 

 

[Sam the Swiss]

Hi, my savannah vg : weight 680Cruise at 5000 : 95 mphMax cruise : around 105 mph

 

No long range tank

 

Fuel burn 15.5 l/h

 

912 uls

 

Mtow 1232

Thank you g2omer for your data. From your avatar I take it that you have no wheel spats. What size of wheels are there on your plane?

[Sam the Swiss]

Hi Sam,OK - I'll start off with data from my Savvy S (from memory).

Empty weight about 310 kg - I have long range tanks, dual brakes, centre stick, adjustable seats, transponder, Garmin Aera 500, manual flaps, electric trim....

 

I usually fly solo, and I weigh about 60kg. With full tanks, and about 7kg of stuff in the baggage my take-off weight is around 470-480 kg.

 

So my figures when solo are usually closer to the old 450kg ones in the POH rather than the 600kg ones.

 

The stall speed gets hard to measure when I fly straight and just slow up as the angle of the pitot is high and not really reading accurately, but with full flap I see it around 25 kts. When clean it is around 30kts, but same issue with pitot at high AoA. (Book figures for 600kg are 30kts and 35kts respectively).

 

I cruise at around 4800-5000 rpm (100hp ULS), and my speed is around 82-83 IAS. I flight plan on 90 kts TAS, with cruise altitude usually over 4000ft AMSL, and over 3 years I have found that to be largely accurate.

 

I get about 15 litres per hour with 98 octane MOGAS (POH figure is 18.5). This gives me an endurance of 8 hours + reserve, which is well past my bladder endurance...

 

I haven't really measured my take-off roll as it varies with wind, surface, etc - but it would usually be less than 200m, and my rate of climb solo is usually 800-1000fpm as the flap extension speed is 60kts so I have to keep the nose angle high enough to avoid exceeding this. I usually climb out at 55kts, and I am frequently at circuit height before turning crosswind.

 

Landing distance is also usually less than 200m or so - I do not try to land short most of the time as it puts stress on the u/c to do this, and as my home field has 1200m of runway I really don't have to! Much shorter landings are definitely possible. Just search Youtube for videos of Savannahs doing short landings - there are many!

 

BTW - see if you can get Revision 6 or later of the POH as that has figures for both 450kg and 600kg MTOW.

 

I hope this helps. I have certainly been happy with my Savannah since I bought it, and there are many Savannah owners/builders in Australia who I think feel the same way.

 

Let me know if there are any other figures you would like, and I will try to supply them from my experience.

 

Good luck with convincing your family!!

 

Regards,

 

Neil

Neil, from your avatar I also take, that you don't have wheel spats on your plane. What size of wheels do you carry?Sam

 

 

[g2omer]

Hi ,Carlisle tire 8.00x6. Turf glide.

 

Thank you g2omer for your data. From your avatar I take it that you have no wheel spats. What size of wheels are there on your plane?

 

 

[Sam the Swiss]

Hi Sam,the Savannah is a good plane to built. Flight data are aviable in some weeks, because I'm just about to start test flights.If you are interested in building, you might want to check www.savannah-blog.de

Hi TomI am following your posts on this site since you started your project, and I am impressed that you are already that far. Thanks for the link and I am looking forward to your data on the performance of your beauty.

 

BTW: You were flying a savannah recently for transition training. Do you remember any data from there? I know, different machine, and a lot of things to get used to…

 

Sam

 

 

[Neil_S]

Neil, from your avatar I also take, that you don't have wheel spats on your plane. What size of wheels do you carry?Sam

Hi Sam,

Correct - no spats. I have the standard 6.00 x 6 tyres, not the Tundra option. I find them fine for the grass strips that I frequently fly into. My hangar mate, who has a Savannah VG, has the Tundra tyres.

 

Cheers,

 

Neil

 

 

[Sam the Swiss]

So far I get the following picture about the cruise speed (which is probably not the most important figure of a Savannah ):

 

ICP advertises 97 kts / 111 mph / 179 km/h cruise using 18.5 l/h

 

They use spats which yield about 6 kts / 7 mph / 11 km/h

 

As they use 18.5 l/h compared to your 15-15.5 l/h, their cruise is measured at a higher rpm, which is at about 20% more energy for propulsion.

 

20% more energy for propulsion gives maybe 7% more speed: Starting from your 83 kts / 96 mph / 154 km/h this would give 89 kts / 102 mph / 165 km/h.

 

Adding for the spats we are at 95 kts / 109 mph / 176 km/h, pretty close to the advertised numbers (1-2% off). So although their cruise is a rather high 75% cruise, their numbers are ok.

 

Any other real world experience with a Savannah?

 

Sam

 

 

[MajorTom]

After my first 15 hours.... 12,5liter 130kmh

 

It ist no fun to fly 150kmh in turbulent summer Weather

 

Climb rate is very good

 

Handling is great