Sag rear spoiler

[Chassis 33]

Please don't start a bun fight, but is the rear spoiler on a Sag functional or cosmetic? The reason I ask is if a few things come good I might have a profile on the Chim racer that could suit a Sagaris style rear spoiler, if it is a functional design, if not I'll use a plane element type wing to get what I need.

Regards
Iain

[Don1]

IMHO, it's more of an air brake than a spoiler...

[custardkid]

i think the phrase your looking for is Gurney Flap... as used in F1

wiki

history

as used else where.......




how effective it is is an other question.....

my work here is done

custard

[deevlash]

Pher DJC did some work on modifying a sagaris gurney flap and other aero bits iirc, might be worth seeing if hes around?

[TVR_owner]

Chassis 33 said:

Please don't start a bun fight, but is the rear spoiler on a Sag functional or cosmetic? The reason I ask is if a few things come good I might have a profile on the Chim racer that could suit a Sagaris style rear spoiler, if it is a functional design, if not I'll use a plane element type wing to get what I need.

Regards
Iain

Iain,
It's functional. TVR did look at an aero aid for the T350 but nothing was developed. I suspect I dont need to tell you, but as with most aero aids, they have an effect on straight line speed - nothing for nothing...

[TGJR]

I was witness to some R&D about 5 years ago at a HHC track day at Croft. A crew from the factory had a T350, a strip of perspex and a lot of gaffer tape! They would do a couple of laps, come in to the pits, adjust things a little with some more tape and then head out again! It must be functional

[TVR_owner]

TGJR said:

I was witness to some R&D about 5 years ago at a HHC track day at Croft. A crew from the factory had a T350, a strip of perspex and a lot of gaffer tape! They would do a couple of laps, come in to the pits, adjust things a little with some more tape and then head out again! It must be functional

Same here Thomas - I was impressed with the attention to detail - the gaffer tape matched the car colour.

Was it really 5 years ago....

[Chassis 33]

Cheers folks, I think the rear wing/spoiler on the Sagaris is a bit large to be considered a Gurney flap, in a technical sense they're generally considered to be less that 5% of the chord length of the wing element that they are attached to, not the entire wing. TGurney flaps are generally only used on a high lift coeff. wings as they reduce trailing edge separation, and increase lift (or in a car application downforce), on low lift wings, they generally just increase drag and reduce the lift/drag ratio.

As for the functional aspect of the Sagaris wing, I think I'm convinced enough to explore the design more. Thanks.

Regards
Iain

[Tangoed]

From what I can remember in past posts, It is functional and should not be taken off. Although its supposed to be more of a wind break at 120mph

DJC did make a slimmer perspex flap so there wasnt as much drag. I can only think of one car that ever had one fitted, this is sag 29 in the register, RPA.Janwell.

TVR Power sell the perspex replacement in clear or smoked. I've often thought of cutting on down to see the differance.

[blackiepaul]

you cans till buy a replacement smaller rear spoiler at a better angle with replacement brackets etc from Edward Quick its about £300 the same one as mentioned on this thread. I am going to get one fitted when I get my slats done.

[Don1]

Would you mind divulging how much it costs to get the slats done, and where? Ta!

[tail slide]

Chassis 33 said:

........... on low lift wings, they generally just increase drag and reduce the lift/drag ratio.

Iain

I went into this with Neill Anderson at TVR (and I checked with an independent race car aerodynamicist) before adding a Sagaris spoiler to rear of my T350 - it IS too big to be a gurney flap as such, but like many others the T350/Sag shape generates lift over the top surface of the car, and a large flap reduces the flow therefore reduces lift a little. On their Croft test day, they found that anything smaller did nothing noticeable.

What's really needed is the flap PLUS a wing, if you can stand how it would look.

[BCA]

tail slide said:

Chassis 33 said:

........... on low lift wings, they generally just increase drag and reduce the lift/drag ratio.

Iain

I went into this with Neill Anderson at TVR (and I checked with an independent race car aerodynamicist) before adding a Sagaris spoiler to rear of my T350 - it IS too big to be a gurney flap as such, but like many others the T350/Sag shape generates lift over the top surface of the car, and a large flap reduces the flow therefore reduces lift a little. On their Croft test day, they found that anything smaller did nothing noticeable.

What's really needed is the flap PLUS a wing, if you can stand how it would look.

Depends how quick Matts Tuscan is surely?

[Chassis 33]

Shirly having a big wing on the back, like for example, on Cliff's T350, would remove the need for the flap as the air flow would be modified by the wing to such an extent nothing much would pass over the flap.

What about a Plymouth Superbird/Dodge Charger Daytona trolley handle?

Regards
Iain

[rpa.janwell]

Made a lot of difference, but only at kilolepton speeds. Found in the upper reaches that the original created a lot of drag, flattening the speed off very quickly when off the throttle. The new version is much smoother, the car still tucks down but does not haul back off the throttle as before.
R

[tail slide]

BCA said:

Depends how quick Matts Tuscan is surely?

I'm expecting the worst! But no wing for me, anyway.

Chassis 33 said:

Shirly having a big wing on the back, like for example, on Cliff's T350, would remove the need for the flap as the air flow would be modified by the wing to such an extent nothing much would pass over the flap.

What about a Plymouth Superbird/Dodge Charger Daytona trolley handle?

Regards
Iain

Theory is that a combination like this could then be sized/arranged so that fixed spoiler would reduce lift relative to underbody airflow, and wing (preferably adjustable for different tracks or top speed etc) would provide downforce with little drag penalty... as often used in GT racing with similarly smooth coupe body shapes.

.. and don't call me Shirly

Edited by tail slide on Monday 8th December 20:04

[donaldosaurus]

blackiepaul said:

you cans till buy a replacement smaller rear spoiler at a better angle with replacement brackets etc from Edward Quick its about £300 the same one as mentioned on this thread. I am going to get one fitted when I get my slats done.

I bought decats from Quicky for my T350T and at the same time he provided a reduced wing and supports modified to suit. Sadly we could not get them to line up when we dry fitted so on advice from X Works service I did not fit them. The decats were things of beauty though, superbly engineered and what a sound! Let me know if you successfully fitted the reduced wing please, Donaldo

[crimbo]

I feel the spoiler is for functional purpose's, From my understanding it may roll the air into a circular motion over the rear screen creating less turbulence over that area and it may also stabilize vortexes behind the car resulting in less drag, The rolling effect above the screen should also create a high pressure pocket which when situated above the lower pressure created by the smooth diffuser under the rear section of the car,should result in the rear section pushing the car down to the ground increasing high speed stability.

Edited by crimbo on Sunday 23 August 23:31

[geordieexpat]

I was thinking of having mine reduced in height - seen it on a orange sag

[tail slide]

geordieexpat said:

I was thinking of having mine reduced in height - seen it on a orange sag

OK if you never go around high speed corners. It has a small but helpful stabilising effect on the rear above 70mph, from my before/after experience on track.