Considering Dropping Parachute Option

Model Specific Discussions about the Sling TSi.
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Mayeuxs
Posts: 8
Joined: Tue Jul 28, 2020 1:09 pm
Location: Charleston, SC

Considering Dropping Parachute Option

Post by Mayeuxs »

Ive been running wt/cg numbers with realistic loading scenarios for my planned mission. 4 average wt people with a reasonable amount of bags. As you all know, keeping the landing cg from going out the back of the envelope is the challenge. Unless I'm doing something wrong with the numbers, the ability to add forward ballast as far forward as possible is a must.

I will be starting with Midwest Skysports and their build assist program as soon as my kit arrives. Henry Rise, the owner, suggested the best way to add forward wt would be to use the hollow interior of the nose strut. He gave me the interior detentions of 2 " in diameter and 25" of useable length. That yields 78.54 in3. If that space were completely filled with water it would only yield 2.83 lb. antifreeze would be only slightly heavier. Filling it with lead would be 32.2 lb. I'm not sure how easy the access is going to be from the top but the ability to add and remove small bags of lead shot would be nice. The ability to add wt to the nose tire itself by filling it with polyurethane foam may also be an option.

The POH shows the nose wheel at 18.268 in aft of Datum. I used 20 in for the added ballast since the strut angles aft slightly as you go up. The more wt you add the greater that number would be since the top of the tube is farther aft than the bottom.

My realistic loading scenario is :

Seats - LF 170 lb, RF 190, LR 115, RR 122

Bags - 59 lb

Landing Fuel - 9 gal

My sample aircraft are - N678CB without parachute. Empty wt 1156, Empty cg 19.69, Empty moment 85081.6

- N135WT with parachute. 1184, 23.57, 89573.6

IF my math is correct, in order to bring the landing cg back into limits, 16.11 lb of forward ballast would be required without parachute and 52.13 lb with parachute. I could live with putting 16 lb or so up there and just leaving it but a total parachute penalty of over 100 lb is enough to drop the parachute option. Im hoping my math is off somewhere.

side note: I was fortunate enough to travel to the factory in SA just before covid came along and get an extensive factory tour. My wife and I flew with James Pitman for over an hour, super guy with lots of energy. We talked a good bit about the parachute and he strongly recommended against it. He said the aircraft is designed to not have it but they included the option later for those who insisted on it. He said it really screws up the CG....now I get it!
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ibgarrett
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Re: Considering Dropping Parachute Option

Post by ibgarrett »

For what it's worth, I'm not putting the parachute in mine. I did get the kit with the cables and through sheer luck my kit will have the skin for the parachute. I just won't install the space around where the parachute will go (I wanted the luggage room). The nice part is if I ever change my mind, the install will be only a few days to do at best. The parachute chews up a big chunk of the luggage space in addition to the CG... Of course putting luggage in that space will do the same as a parachute would...
Brian Garrett
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geoff_g
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Joined: Sat Mar 20, 2021 2:51 am
Location: Canberra

Re: Considering Dropping Parachute Option

Post by geoff_g »

Does the chute alter the max allowed weight in the baggage area, or just affect the CG?
I have the chute in my 4, but the baggage area is still placarded as max 35kg - does the 20kg chute in reality make up part of this 35kg allowance?
Never thought about it really until now, but then never had anything other than really light gear in the back yet...
Geoff G

Sling 4 - VH-KMQ
Canberra, Australia
Mayeuxs
Posts: 8
Joined: Tue Jul 28, 2020 1:09 pm
Location: Charleston, SC

Re: Considering Dropping Parachute Option

Post by Mayeuxs »

I don’t think the chute counts against the 35kg.
wheath
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Joined: Fri May 28, 2021 9:50 pm
Location: Richmond, VA

Re: Considering Dropping Parachute Option

Post by wheath »

Are you including an external alternator? From what I've read, a lot of people are including them primarily as a way to bring the CG forward, extra electricity is just a bonus.
Mayeuxs
Posts: 8
Joined: Tue Jul 28, 2020 1:09 pm
Location: Charleston, SC

Re: Considering Dropping Parachute Option

Post by Mayeuxs »

Yes, I’m going with the external alternator for the reasons you mentioned. I’m not sure if the sample aircraft I used, N678CB and N135WT, have have it or not. Even with the alternator, the ability to add some wt as far forward as possible would be a handy option. It would only be necessary to counterbalance a heavily loaded airplane.

Thanks,
Steve Mayeux
vas4slingforum
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Joined: Tue Mar 01, 2022 4:56 pm
Location: SF Bay Area

Re: Considering Dropping Parachute Option

Post by vas4slingforum »

Hello,

I am a new member on this forum and also new to the whole world of experimentals - I am actively considering the TSi and have been going through the same calculations about the parachute. I'd like to be able to transport a payload of 700 lbs (380 lbs in the front, 300 lbs in the back seat, 20 lbs of bags) and I am willing to settle for a range of 2 hours (3 hours with reserve). With the chute, it looks like even though the weight may be ok, the CG starts off too far aft and then goes even further aft as fuel is used.

It looks like most of the posts here were from 2021 so I wanted to revive it to see if any of you were able to use a counterweight to bring the CG further forward when needed (not permanently).

Also, if one orders it with the chute, is it a realistic option to be able to take it out when I want to carry a larger payload?

Thanks,

Vas
Brad
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Joined: Wed Jan 01, 2020 12:18 pm
Location: New Zealand

Re: Considering Dropping Parachute Option

Post by Brad »

is it a realistic option to be able to take it out when I want to carry a larger payload?
Nope, that is not (really) possible.

We are weeks away from the final weighing of ours with a couple of modifications:

1. Removal of the elevator counterweight as per the SB
2. A full IFR suite (fair bit of weight)
3. Plates in the front cockpit floor to stiffen up the floors + get some weight forward
4. BRS parachute instead of the Magnum 901 - reduced weight
5. Weight blocks in the rudder pedal channel (as required to meet our CG goals).

Will report our findings soon.
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lutorm
Posts: 76
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Re: Considering Dropping Parachute Option

Post by lutorm »

I have no idea if this is possible, but the thing furthest forward are the propeller blades... Are there different blade options with different weight? I seem to remember the default prop is carbon fiber, but it seems once you start talking about building in ballast, are there are any drawbacks to using blades that might be heavier instead? (I haven't made the calc of how much heavier they would have to be to make a difference, though, and presumably there are weight limits imposed by Rotax or Airmaster.)
Blog of various projects: https://blog.familjenjonsson.org/blog/
scout
Posts: 25
Joined: Mon Nov 22, 2021 5:31 am
Location: US

Re: Considering Dropping Parachute Option

Post by scout »

Brad wrote: Wed Mar 02, 2022 5:07 pm
is it a realistic option to be able to take it out when I want to carry a larger payload?
Nope, that is not (really) possible.

We are weeks away from the final weighing of ours with a couple of modifications:

1. Removal of the elevator counterweight as per the SB
2. A full IFR suite (fair bit of weight)
3. Plates in the front cockpit floor to stiffen up the floors + get some weight forward
4. BRS parachute instead of the Magnum 901 - reduced weight
5. Weight blocks in the rudder pedal channel (as required to meet our CG goals).

Will report our findings soon.
Any update on these ?

Personally, I like 1, and 2,
When it comes to 3 and 5... Adding weight forward more, with less of an arm, would have a greater effect on cg. ie something on the front of the engine where the external alternator would be. Like a lead weight would help more.
4. The BRS chute is nice. But the magnum is $5k roughly and the BRS is $13k roughly. And the BRS is only about 2-4lbs less. Not sure its worth it for that difference.
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