cactusflyer

My Feedback: (4)

Harry, Mostly correct on the Sabre slats. There was no spring to push them out, just gravity. On the ground, they would extend of the way due to their weight. If they extended in the air, it was because they needed to be!..............air loads did all the magic. With a model, it might be difficult to duplicate this effectively. The slat tracks on the full scale plane were very loose and free moving. So some help from servos is needed to ensure symmetrical movement. I think the biggest concern on the model is the strength of the gear train. Small servos are all that is needed to overcome the track friction, but it would be a bad thing if one servo got messed up while handling the model and the other remained intact due to a weak gear train.

The leading edge FLAPS are whole different ball game. I have seen linkages/servo failures where the flap extended TOO FAR. The linkage failed and the FLAP hinged all the way back against the lower wing surface.

Tailwinds,

John

uncljoe

My Feedback: (8)

Jeff T did an OUTSTANDING job of Landing when he had a slatdeploy on his F 16 . BTW he was back in the air later that afternoon
Semper Fi

RBardin

My Feedback: (27)

I was glad to learn about the scale operation of the F-86 slats, I never took the time to find out how they work. After thinking it over, I'm going to seperate mine to work in unison with the flaps so they can help with takeoff also.

Rex do you have any pics of the ones you just did? I remember seeing the wings in your shop but don't understand how or where the servo is situated in the F-18 wings. Why does it only have one per surface? Would a small air ram work for them as well? or electric? or servos are best? What servo did you use?

Uncle Joe, what servos were in that F16? Great pics, per usual!

CHARLES WINTER

Hi Jet Pilots This brings back memories when I was flying F-86Ds (1954). During the pre-flight (preparing for flight) we would check the leading edge slats by pushing them up by hand and then letting them slide back with a Bang when they dropped down to the hanging position. During takeoff you could see the slats slide back into the leading edge. During "Rat Racing" Practice Combat maneuvers when you approached a high speed stall the slats (Sometimes just one wing slat would POP/Bang down) but go right back up into the wing leading edge. A few pictures to enjoy. Col. Chuck Winter

FenderBean

well from the pics it appears mine will be slats so I guess my orig post title was correct [:-]

rctech2k7

My Feedback: (1)

FenderBean, don't worry Harry put 2 additional interesting things on your topic, (1) difference between slats and LE flaps (2) automated slats originated from full scale F-86. Actually slats and LE flaps are two different devices with different characteristic but both function as high lift devices (HLD) located in the leading edge of the wings. For model planes it has been a practice to name them as the same. As per model jet advancement this could be the chance to update them in order to specify correctly.

For me, HLDs in the front of the wings are really complicated and the benefits are not that big other than for low speed maneuver. These LE HLDs have their advantages over each other and varies depending on a lot of circumstances. However I know these devices will be helpful not just for scale look but performance on takeoff, landing and missed approach especially now that our jets are developing as far as the size and weight are concern.

This is what I can say about landing with these LE HLDs, the approach must be slightly higher AOA, airspeed is lower, power may varies depending on the drag, I mean more drag at higher angle. If done in the same manner during flaring it could cause to increase altitude because of the lift added then sink rapidly if power is not applied on time. However the sink rate is not that high compare without LE HLDs so the gear might handle the impact which may cause broken gear compare to just flaps only. Flaps increase drag while decreasing lift effectiveness at higher angle causing the wings to stall when airflow separates. But these LE HLDs delays that separation of airflow over the wings causing them higher lift. In short the jet may land like a dream or like a trainer in either way you prefer.

About mechanical automation this is possible as it takes energy from the airspeed of the jet, it may only lessen the speed efficiency. However there are still other factors like size, complexity of mechanism and fail-safe. Electronics these days may take-over this feature with the help of sensors and actuators or servo, they can be design to program with different parameters so they can work depending on our model setup. The pilot must be aware during low airspeed at any position the automation might take-over to prevent the aircraft from stalling. This is more than just flying. The situation of an aircraft is different on low altitude when recovering from stall because during negative alpha slats are not effective. Flaps may hook up the same thing also but there should be an option to override in manual if needed by connecting cable form the Rx to the controller as the actuator or servo works as an regular radio control.

rctech2k7

My Feedback: (1)

Col. Chuck Winter, thanks for sharing that info and memorable pictures. I know a person like you has plenty of story.

rctech2k7

My Feedback: (1)

It seems the jet was confused by the critical mach.

JohnMac

Hi Col Winters,
Thanks for posting the photos. I think that this was a really intersting period in aviation history. I would have been the grand old age of 1 when you were having fun with the Sabres. I am just bulding a Sabre right now. Prettiest American jet ever built IMO.
Enjoy your flying sir.
John

JohnMac

Fenderbean,
I am confused. What model are you building or at least considering to add LE Flaps or slats to? You mention a F16. This had LE flaps. I suspect the F16 wing was too thin for Slats. LE Flaps can be added to the thinnest wings, the F104 for example.
If I was to build LE flaps on a model I think I would add very strong mechanical stops to prevent the kind of incident we see in the F16 pictures.

John

cactusflyer

My Feedback: (4)

Almost..........here is an excerpt from the Wiki files:

"Handley Page also developed the Handley Page Slat (or slot, see slats), an auxiliary airfoil mounted ahead and over the main wing, which formed a narrow opening running along the leading edge of the wing to improve airflow at high angles of attack.[2] The leading edge slat was simultaneously designed by the German aerodynamicist Gustav Lachmann, who was later employed by Handley Page. The design was so successful that licensing fees to other companies was their main source of income in the early 1920s."

Retractable slats that relied upon aerodynamic force for retraction were used on the outer wings of the Me-109s way before the F-86.

Tailwinds,

John

FenderBean

No its not my f16 Im going to hold off with further questions till I can see the design. Its probably going to hinge flap from a point. I will post when I find out I was guessing it would have been a general type response not aerospace design discussion [8D]

BobbyMcGee

I would think starting the topic all over again is a frivolous idea. Especially sinceit isentitled, "Leading edge slat/FLAP servo torque question." By having that title, both situations are covered. No need to split hairs anyway.

Besides, we know what FenderBean is referring to. It's not like we don't understand, or can mistake the front of the wing for the fuselage or tail section. Besides, he is trying to get an answer for torque. So, lets just get on with what torque is needed to deploy the leading edge system. But it sounds to me, he got an answer. I like the calculations on the spreadsheet. I didn't know all that engineering was needed to figure this stuff out. Very interesting!

Either way, LE flaps or slats will yield the same result ... a high-alpha approach and landing. Sounds to me, that 'high-alpha'isthe end resultFB is seeking.

My F-16 lands pretty flat when I deploy flaps. So, I land without them and get a higher AoA on final approach and landing. Not a high-alpha, but a nice touch-down on the mains first.

marc s

For those who have not seen this Yak 130 build there are a few shots of a quite stunning piece of model engineering in the LEF's.

[link]http://www.youtube.com/watch?v=IzJablEAGW8[/link]

marcs

RBardin

My Feedback: (27)

+1


That Yak is beyond belief! Thanks for the link!

CHARLES WINTER

Hi Jet Pilots, I am enjoying all the posts. A few more pictures for you to ENJOY. Col. Chuck Winter

BobbyMcGee

Well, that blows away any kind of work I can do! DAMN!

At least I use the same hand tools and JB Weld as they do. But I have a long way to go before I get to that level.


I'd like those guys to build my next jet ... If I can afford them!

FenderBean

I orig asked about slats I, know there are also flaps but since people started in on flap vs slat I added it to the title. I think both in a rc jet depending on the design will require similar torque, both are being pushed/pulled via a servo. It just depends on how each are built as to the load the servo will get. I will wait to see how these are designed and come back to the topic.