Forward Slip with full flaps RV-7

[Valdas]

I am a first time poster here and a wanna-RV7-be Last Saturday I had an opportunity to be a passenger in a RV7 and I was so impressed, that shortly after I bought a second hand empennage kit on ebay
However, my question relates to flying praxis - my fellow pilot said that forward slip in a -7 with full flaps would overstress the flap(s) and should not be practised. Is that true?
I fly at a 1500' farm strip which abuts a forest at one end and has additional slope on the other. I need to perform a forward slip with full rudder deflection with such a light and slow aircraft as Kitfox to come down here from that direction...

 

[hecilopter]

Never heard of it

However, my question relates to flying praxis - my fellow pilot said that forward slip in a -7 with full flaps would overstress the flap(s) and should not be practised. Is that true?

Vfe is 100 mph and Vso is near 54 mph in my plane. I have done many full forward slips without issues. I does come down fast though!

As long as you are under 100 mph I don't see any issues with the flaps down. Never read any warnings from Van's about this either.

Just be careful and keep the speed up as you wouldn't want to stall (and spin in) in this configuration!

 

[hevansrv7a]

I do it often

I never heard that I was not supposed to. I use slips to control altitude on final. I don't see the difference between that and one kind of X-wind technique.

However, I draw the line at back-of-the-curve approaches. While they are better for very short fields, I don't mix that technique with slips. Back of the curve in this context means slower than the speed for minimum sink and I use the AOA when I do it. For those, I use power to control altitude especially because pitch is so critical in that condition.

YMMD.

 

[cjensen]

I've made several full deflection slips with full flaps...no issues here.

 

[roee]

I've never seen such a warning from Van's, and I don't see why there would be. Some aircraft (e.g. some high wing Cessnas, not RVs) are prohibited from performing slips with the flaps down because it interferes with the airflow over the tail surfaces and so can lead to control problems. But in any case, I don't see why a slip would increase stress on the flaps themselves.

 

[Mel]

No problem at all!

I also fly out of a 1500' strip and I slip regularly.
No problem at all slipping with full flaps as long as you are at or below Vfe.

 

[Norman CYYJ]

I never heard that I was not supposed to. I use slips to control altitude on final. I don't see the difference between that and one kind of X-wind technique.

However, I draw the line at back-of-the-curve approaches. While they are better for very short fields, I don't mix that technique with slips. Back of the curve in this context means slower than the speed for minimum sink and I use the AOA when I do it. For those, I use power to control altitude especially because pitch is so critical in that condition.

YMMD.

Power is always used to control altitude and pitch (elevator) controls speed.

I've never had a problem with forward slips just make sure that your speed is above the stall.

 

[sandifer]

Just be careful and keep the speed up as you wouldn't want to stall (and spin in) in this configuration!

No need to carry any more speed in a slip than for a normal approach. Try to stall your airplane sometime in a full slip. I've only tried in the RV-3, but it would not truly break, which also means it never came close to spinning even with the stick held fully aft with full rudder. Just be careful coming out of the slip. If you kept rudder in while taking out too much aileron, got too slow and hamfisted with the stick, then you could possibly depart into a spin.

 

[compren]

Slip - Indicated Airspeed

"No need to carry any more speed in a slip than for a normal approach."

I've noticed, at least when I fly the spam cans (not done with my -7 yet), that depending on which way you slip, your indicated airspeed can vary by as much as 20 knots (in a C-172). If your on final, 20 knots can be a pretty big discrepancy. I think it has to do with the static port pressure increasing / decreasing depending on which way you slip. Maybe someone else can explain it better than I.

In any case, be sure you are familiar with your aircraft when your slipping it in...

 

[scard]

"No need to carry any more speed in a slip than for a normal approach."

I've noticed, at least when I fly the spam cans (not done with my -7 yet), that depending on which way you slip, your indicated airspeed can vary by as much as 20 knots (in a C-172). If your on final, 20 knots can be a pretty big discrepancy. I think it has to do with the static port pressure increasing / decreasing depending on which way you slip. Maybe someone else can explain it better than I.

In any case, be sure you are familiar with your aircraft when your slipping it in...

Hence the comment about using AOA and not relying too much on direct airspeed indications in such a configuration.

 

[Bill Dicus]

Slip

Does the 172 have static port on only one side? Very old 172's were like that so slipping toward the port gave a decrease in IAS and away from it an increase. Since the RV's have two static ports on opposite sides I would think IAS would be the same regardless of slip direction. Has anybody experimented to see if this is true? The combined pitot-static tube on the Pitts gives the same IAS either way.