Weight & Balance AFT CG Concerns

[msejourne]

SLING TSI - Weight & Balance (W&B) Concerns

I haven't bought nor built my Sling yet but while planning & reading all the manuals, I created an Excel Spreadsheet to run various W&B examples. It works perfectly, matches exactly the POH examples, and it warns me immediately if any weight or CG limitations are exceeded for both Take-off & Landing.

HOWEVER, since I don't have real aircraft numbers (Empty Moment/Empty Weight = CG), I am forced to use the sample aircraft values in the POH. Unfortunately, using those values I am running into consistent AFT CG issues so I suspect that the POH sample aircraft may not reflect accurately more traditional numbers we should see.

Therefore, in order for me to use realistic numbers, I would like to ask if you guys could please share your real aircraft W&B numbers with me? To also mention whether you have or do not have, the (17.6 kg/39 lb) Magnum 901 Parachute which worsens the AFT CG issue. NOTE: Then numbers can be Metric of Imperial, it doesn't matter I am running both in my spreadsheets.

Example:
N113EB
Parachute: NO
Empty Weight (EW): 1095 lb
Moment: 6570
CG: 6.08 ft

or

N661MG
Parachute: YES
Empty Weight (EW): 1134 lb
Moment: 6917
CG: 6.10 ft

YOUR KIND ASSISTANCE IS GREATLY APPRECIATED!

Best regards,
Mike

[ncs]

Not mine, but Barry from TAF USA sent me the weight and balance sheet for N135WT (extended range tanks + parachute I believe). Here are the numbers, but it'd probably be easier to use them if you ask him for the spreadsheet directly.

Item Weight (Kg) Weight (lbs) Arm (mm) Arm (inches) Moment in/lbs
Aircraft Empty Weight and Empty CG 537.50 1,184.98 1,920 75.59 89,573.64
Fuel (66 Gallons Maximum) 0.0 gal 0.00 1,800 70.87 0.00
Pilot and Passenger Weight 0.00 1,902 74.88 0.00
Passengers Rear Seat 0.00 2,948 116.06 0.00
Rear Baggage 77.16lb or 35Kg combined max 0.00 3,288 129.45 0.00
Rear Baggage Extension 0.00 4,088 160.94 0.00

[msejourne]

Thank you for the data NCS, unfortunately I don't have Barry's contact details.

[PhilipRueker]

Thank you for the data NCS, unfortunately I don't have Barry's contact details.

You can reach him at TAF USA - https://www.airplanefactory.com/contact/

[msejourne]

Thank you Philip!

[N828BW]

I was just at the factory last week and we spent some time with getting the weight and balance configurations set up in ForeFlight and it definitely gets aft of GC quickly. The numbers we used were from Wayne’s plane N135WT as a base until my plane gets here. I could share the number used in ForeFlight if I can figure out how to attach a picture lol.

[msejourne]

Greetings, thank you for your response but I managed to gather enough data via the "Sling Builders" group on Facebook. Now I'm just going to play with it to substantiate having more weight FWD such as LR tanks and the Optional Alternator. Thank you kindly! Mike

[msejourne]

CAUTION
Beware that although these numbers from N135WT came from Barry @ TAF USA, the Arm used for the Fuel is INCORRECT as it shows ALL Fuel including the Long Range (L/R) Tanks Fuel under only 1 Arm. However, as per POH Rev 2.2 it should be as follows:
FUEL Main (46 Gallons Maximum): Arm (mm) 1,800 Arm (inches) 70.87
FUEL L/R (20 Gallons Maximum): Arm (mm) 1,822 Arm (inches) 71.724

Note: Although that does not help the AFT CG problems for landing, usually that Fuel from the L/R Tanks would have been transferred to the Mains.

Not mine, but Barry from TAF USA sent me the weight and balance sheet for N135WT (extended range tanks + parachute I believe). Here are the numbers, but it'd probably be easier to use them if you ask him for the spreadsheet directly.

Item Weight (Kg) Weight (lbs) Arm (mm) Arm (inches) Moment in/lbs
Aircraft Empty Weight and Empty CG 537.50 1,184.98 1,920 75.59 89,573.64
Fuel (66 Gallons Maximum) 0.0 gal 0.00 1,800 70.87 0.00
Pilot and Passenger Weight 0.00 1,902 74.88 0.00
Passengers Rear Seat 0.00 2,948 116.06 0.00
Rear Baggage 77.16lb or 35Kg combined max 0.00 3,288 129.45 0.00
Rear Baggage Extension 0.00 4,088 160.94 0.00

[ncs]

CAUTION
Beware that although these numbers from N135WT came from Barry @ TAF USA, the Arm used for the Fuel is INCORRECT as it shows ALL Fuel including the Long Range (L/R) Tanks Fuel under only 1 Arm. However, as per POH Rev 2.2 it should be as follows:
FUEL Main (46 Gallons Maximum): Arm (mm) 1,800 Arm (inches) 70.87
FUEL L/R (20 Gallons Maximum): Arm (mm) 1,822 Arm (inches) 71.724

Note: Although that does not help the AFT CG problems for landing, usually that Fuel from the L/R Tanks would have been transferred to the Mains.

Thanks for pointing that out. At a change of 0.05" it doesn't practically affect the scenarios I was looking at, but it is good to have it correct regardless.

[msejourne]

UPDATE
A couple hours ago I received the exact CG ARM from TAF Engineering for the External Alternator and as suspected, It is only 3.8 mm / 1.5 in, which is wayyyyy better that my estimate of 9 in. Therefore the data below has been updated accordingly.

Gentlemen, I completed my Excel file with the Imperial (i.e. Pounds & Inches) as well as Metric to compare the following Sling TSI versions:

- Basic Aircraft
- L/R Tanks Option, and
- L/R Tanks + Ext. Alternator Options.

I realize most of us have different mission intentions for our Slings and this will most likely generate many discussions/debates/opinions. My mission is mainly like it was with my C-177 Cardinal RG, which was for Long Range X-Countries with a min. of 3 adults. I realize there are many different ways to skin a cat but in order to make fair comparaisons, the conclusions that I have drawn are based on the assumptions below.

Front seat.........190 lb
Front seat.........125 lb
Rear seat..........110 lb
Rear seat.......... 70 lb
Pilot/Pax Total...495 lb
Baggage............77 lb
Payload total.....572 lb

ASSUMPTIONS
1. Range assuming 8 GPH @ 150 Kts TAS (no wind)

2. For the external alternator kit, it’s 6.61 lb and the ARM has been confirmed to me by TAF Engineering to be 38 mm / 1.5 in.

BASIC AIRCRAFT
• Unable to use full payload capability
• Only 33 USG, approx. 4.1 hr flight
• Range 619 nm
• 1+30 hr Fuel Reserve

L/R TANKS OPTION
• Max Ramp Weight on departure
• 46 USG avail, approx. 5.75 r flight
• Range 862 nm
• 1+45 hr Min Fuel Reserve

L/R TANKS + EXT. ALTERNATOR OPTION
• Max Ramp Weight on departure
• 53 USG avail, approx. 6.6 hr flight
• Range 994 nm
• 45 min Fuel Reserve
OR
• 55 USG avail, approx. 6.875 hr flight
• Range 1,031 nm
• 30 min Fuel Reserve

NOTE: In March 2021, the Main and Long-Range fuel tank sizes changed

For all those interested in obtaining this FOR TRAINING ONLY Excel File, please send me an email at mikesejourne@gmail.com with the following choices:

1. Choice of Imperial or Metric; and
2. Fuel tank version i.e. BEFORE or AFTER March 2021

Cheers!

Mike Séjourné