max weight

Model Specific Discussions about the Sling TSi.
Post Reply
Striker
Posts: 6
Joined: Thu Aug 26, 2021 2:47 pm
Location: Virginia

max weight

Post by Striker »

I hope all pilots understand the importance of staying within CG and max weight. So I am not suggesting breaking that...

As a engineer I can't help but to be curious and want to understand how limits are set...
I am curious what is causing the max weight to be 2094. I see the max weight on the chute is 2094. Seems odd that they would be exactly the same. Was the plane's max weight designed to match the chute max? ( Magnum does have a chute that goes to 2700. just saying. obviously that's to high for the tsi )
But what is the next highest limiting factor ?? The landing gear ? The wings ? Performance specs, take off distance, stall speed ?
IF a plane was simply designed without the chute, what would the max weight be, 2095, 2096 ?? I realize taking the chute out in reality just effects useful load... But how did the 2094 number get into the original design ? If it was simply taking from the chute limit and they applied to the plane.... What would that mean if it wasn't ?

Sorry, I know that's not a very clear question.
User avatar
Will
Posts: 3
Joined: Thu Sep 16, 2021 2:53 am
Location: Cape Town

Re: max weight

Post by Will »

I recommend googling it, however to my understanding, the max weight is calculated per plane.

1st off I believe the plane is weighed with nothing in it, and this is considered its "empty Weight", I think. But you can also just check the Pilots operating manual for the Sling Tsi and I seem to remember that it gives you more info. :D
User avatar
ibgarrett
Posts: 192
Joined: Mon Aug 03, 2020 8:22 am
Location: Westminster CO
Contact:

Re: max weight

Post by ibgarrett »

To calculate a standard empty weight: This weight consists of the airframe, engines, and all items of operating equipment that have fixed, permanently installed locations in the airplane, including fixed ballast, hydraulic fluid, unusable fuel, and full engine oil. :)
Brian Garrett
User avatar
hpmicrowave
Posts: 27
Joined: Mon Nov 23, 2020 6:43 am
Location: FtWalton Beach FL 18FD

Re: max weight

Post by hpmicrowave »

You can talk to Mike, Jean, or James, during their round the world flights they flew the 2 & 4 sweaters many hundreds of pounds over published gross weight. The planes will fly in this condition but it definitely affects aerodynamics, handling, reduces safety margins and performance. Outside of the parachute weight limit their has to be a weight and CG envelope that defines the basis for published aircraft performance and safe flight envelopes. But as an experimental aircraft you the builder can define these parameters yourself, of course at your own risk.

Cecil
Cecil Jones
Building Sling TSi (Low Wing)
Built/Flying Vans RV8
FtWalton Beach FL/Baker FL 18FD
User avatar
lutorm
Posts: 76
Joined: Fri Jan 28, 2022 11:00 pm
Location: Sweden

Re: max weight

Post by lutorm »

I dunno about the Sling, but I've been a member of various canard email lists for a long time and the max gross weight question always comes up. I think in the case of the Long-EZ, Burt Rutan deliberately did not publish any information about the design loads for any components, because he knew it would immediately be second guessed by builders who would argue for one reason or another that it didn't apply to them.

There's a great piece by Dick Van Grunsven called "who owns the margin" about this. Here's an excerpt:
Along with gross weight increases, some builders take the same liberties with horsepower increases and speed increases, betting their lives on the assumption that the airplane is designed with a huge margin of safety---it is really far stronger than in needs to be. This is not really true. Certificated aircraft, and well-designed kit aircraft, are designed to withstand limit loads at specified maximum weights. During testing, they are subjected to ultimate loads, which are higher than design limit loads by a specified margin. Yes, there is a margin between the design and ultimate strengths. But that margin belongs to the engineer. He owns the margin. It is his insurance against the things he doesn’t know or can’t plan for, and the pilot’s insurance against human error, material variations, and the ravages of time. Wise pilots respect this design safety philosophy and leave this insurance policy in effect by operating strictly within established limits. They don’t try to steal the margin from the designers.
Blog of various projects: https://blog.familjenjonsson.org/blog/
Post Reply