Hellcat flaps

[Chad Veich]

Can someone familair with the TFC Hellcat, or Hellcats in general, tell me what is going on here? Notice the inboard and outboard flaps are not equally deployed. A wartime training video indicates that the Hellcat has only two flap positions, full up or full down. So what's going on in the pic?

[Mark_Pilkington]

not sure, but the same aircraft can certainly deploy the main flaps fully down?




Is it possible the your still photo shows the flaps during the extension to full flap, rather than in a locked half flap position?


Regards

Mark Pilkington

[mlenoch]

Hellcat flaps will blow up (retract) if airspeed limits are exceeded.
In the photo, the aircraft likely is flying too fast for the flaps selected, thus showing this deployment configuration.
VL

[Old Shep]

Ditto what Vlado said...F6F flaps will "blow up" if speed is too fast. My dad (VF-15/VF-771 Hellcat pilot) is the source.
Old Shep

[Chad Veich]

Thanks for the info guys. I was aware of that feature on Wildcats but never though about it being applied to the Hellcat as well. Mystery solved.

[bdk]

They may also have been deploying. Perhaps the inboard flaps deploy more quickly than the outboard flaps.

[JDK]

Interesting thread -

Hellcat flaps will blow up (retract) if airspeed limits are exceeded.

A couple of questions - it looks in the first photo that they are deployed aft (before rotating down?) leaving a slot and making them slotted flaps - is that correct?

If the aircraft exceeds the limiting speed with the flaps down, can or wopuld they 'fold up' at different moments on each side, and if so would that affect handling, or would the speed be high enough to overcome the different wing-lift factors?

[daveymac82c]

very interesting thread. I like it. It's so nice to learn something new.

Were there any other fighters from that era that had blow-back flaps besides the two already mentioned?

-David

[Michel Lemieux]

Same question as James.

Either pneumatic or hydrolic systems will deliver "force / movement" where there is less resistance first. That is why gears never go up or down in sequence. To do so would mean equal pressure drop on both side.

Anyone whom has played with a piece of machinery operating with hydrolic equipment will tell you so. Until you've put your hands on a mechanical digger, you've still got to understand the dexterity required to operate one.

But what about flaps ? What makes them go up or down in equally on both side during up or down movements ?

Do they have somekind of positionning feedback system ? Are they linked mechanically ?

I would expect as BDK suggest that both inbord's deploy equally and the same for the outbords

A question for the uneducated masses....Sorry for the bad french spelling.

[skymstr02]

The Grumman F6F, F7F and F8F have what is called a restrictor oriface in the lines to the wing flaps, that allow the flaps to be blown back up in an overspeed condition, but they also restrict the hydraulic flow to the hydraulic cylinders so that one does not get more volumn than another. The oriface is very small, and any piece of FOD will obstruct this oriface and cause a split flap condition.

I can't tell you how many times that I've had to remove these and clean them, and I can assure you that the location makes this a "rectal ripper" to R & R one of these!

[mustanglover]

Interesting thread -

Hellcat flaps will blow up (retract) if airspeed limits are exceeded.

A couple of questions - it looks in the first photo that they are deployed aft (before rotating down?) leaving a slot and making them slotted flaps - is that correct?

Looks to be more of a fowler flap arrangment to me.

[Chad Veich]

...it looks in the first photo that they are deployed aft (before rotating down?) leaving a slot and making them slotted flaps - is that correct?

Yes, they are slotted and have a door just forward of the flap that retracts to form the slot much like a Corsair.

[ALU]

Corsair has also the blow up system. A by pass valve allow the flaps to blow up when air loads become excessive.
On F4U-7 limitations are the following:
With Blow up operative
Flaps from 0 to 50° 200Kts
With Blow up inoperative
Flaps 50° 130Kts
Flaps 40° 145Kts
Flaps 30° 170kts
Flaps 20° or less 200Kts

[mtpopejoy]

I have heard that Navy pilots in WWII would place the flap handle in the down position while in combat in case the speeds dropped to low the flaps would automatically deploy to produce more lift then blow back up when speed increases. It seemed to work pretty well while flying in Aces High II
Any merit to this?

P.S. Great pictures Mark and Chad!!!

[Dan K]

I have heard that Navy pilots in WWII would place the flap handle in the down position while in combat in case the speeds dropped to low the flaps would automatically deploy to produce more lift then blow back up when speed increases. It seemed to work pretty well while flying in Aces High II
Any merit to this?

Here's a little something I lifted from the FOF site. Kermit speaks:

The Wildcat has an interesting flap system that is activated by the vacuum system in the airplane and is also used to spin the gyro instruments for instrument flying. Instead of using positive pressure to operate the flap cylinder, this aircraft uses negative pressure or suction. A large tank in the rear of the aircraft stores the negative air pressure. At higher speeds, the negative pressure does not create enough force to overcome the air loads to lower the flaps. It will not hurt the system, as in some aircraft, to put the flaps down at high speed. They just simply won’t come down! Pilots could use this to their advantage in a dogfight and could select the flap handle down before engaging another aircraft. If during the dogfight the airplane happened to slow down below a certain speed, the flaps would creep out. The more the aircraft slowed down, the more flap would creep out. This gave the Wildcat a tighter turning radius, which was a major advantage in a dogfight, as they could potentially turn inside their opponent and get on his tail.