Elevator counter weight removal

Model Specific Discussions about the Sling TSi.
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scout
Posts: 5
Joined: Mon Nov 22, 2021 5:31 am
Location: US

Elevator counter weight removal

Post by scout »

There is a new optional service bulletin ( aimed at the uk market ) about removing the center elevator counter weight. It suggests removing it to help prevent full power, full aft cg pitch problems. It says the center weight is 1.2 kg (2.6 lbs) Because the center weight has such a high/far back arm removing it, does move the cg forward about .3 of an inch. which isn't much but it does help.

So I can't help but to wonder....
How much do the side weights on the elevator weigh ? would removing them also help even more ?
What does removing those weights do to the feel of the stick? The SB says no significant change but how can that be.
Could the weighs be replaced by a spring ?
Would removing the trim servo and making the trim on the elevator 'ground adjustable only' help much ? it also weighs some 4 oz.
MstrAv8r
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Joined: Tue Nov 09, 2021 5:07 pm

Re: Elevator counter weight removal

Post by MstrAv8r »

When thinking of this, I immediately think of elevator flutter issues. I hope the engineers have done their homework on the issue.
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ibgarrett
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Location: Westminster CO
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Re: Elevator counter weight removal

Post by ibgarrett »

I agree - I had the same thought. Apparently it's a UK requirement. It's hard for me to believe that a governmental regulation is requiring an engineering change (or work around) on an airplane...
Brian Garrett
scout
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Joined: Mon Nov 22, 2021 5:31 am
Location: US

Re: Elevator counter weight removal

Post by scout »

Agreed. Introducing Flutter would be the concern.

Sling, made it an optional SB/notification.

(my understanding)
In the UK they treat all experimental as certified. Thus all optional SB's/notifications are mandatory.
(/my understanding)

If you read Sling SB it sounds very ominous. So I can understand why they'd follow it.
Says," Sling 4 TSi aircraft displays mild static longitudinal instability.....There is a tendency, following the release of the stick after a pull, for the nose to continue to climb slowly, in a divergent manner from the trim speed, until the aircraft enters a gradual stall. The instability condition, while marginal, has the consequence that the aircraft fails to meet, at the corner condition, the requirements of paragraph 23.175(a) of the FAR 23 airworthiness standard ..."

Apparently, Sling did say they tested it under different conditions and it did not introduce flutter.. and according to a FB post, other Sling owners have already done the change and have no problems with flutter or handling.
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