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Extended flying with 20 degree flaps?

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Darren S

Well Known Member
Hey all,

My Pops flies a Titan Tornado (Ultralight, 90 knot cruise). For his 75th bday we're flying across Canada in August. I had planned to borrow a Kitfox to fly but it's proving tricky with insurance and crossing into the US.

We're flying from Calgary to Toronto down through the US.

Anyways, my buddy suggested I fly my -7, 20 degrees flaps, throttle pulled back, LOP.

I can do 100 knot cruise I think? I'll drag the flaps to keep the nose down for engine cooling but......question part here.

Is there any chance of doing damage to the flap mechanism by doing this for 30+ hours?

I don't know the structure well enough to know. Hopefully someone can comment.

Thanks

Darren
 
what I do

I regularly fly my -4 with a Pacer, Cub, L2/L3, and even a some Helos.. 90 kts is faster than some of them. I don't fly with flaps out, but rather way back on the throttle and just lumber along. I have tried the flaps out, but you will find it is better just to leave them up. On longer flights, I simply make an occasional burst to normal speeds and circle around for a regroup. You will burn way less fuel..other than that, no worries!
 
Your RV-7 won't be very happy at 90 knots, but probably a lot happier than an RV pilot who will most likely run out of patience just a few hours into the adventure. I've flown formation with 'slow' aircraft but after a few minutes I've had enough of the RV-6 mushing through the sky.

I can't imagine doing this for 30 hours....even with a treasured companion. Consider riding an 1100cc sport bike at jogging speed for thirty hours.....

Maybe you can still find a more appropriate aircraft for this memorable trip. Best wishes for a great time with your dad!
 
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Do you have electric flaps?

If so, then use about 10 degrees. It will still make the airplane fly at a much lower AOA but wont put much load on the flap system.

Otherwise, as long as you don't go above Vfe you should be ok with 20 degrees for an extended period of time, but it won't really make it any better than 10 degrees other than worsening your fuel economy.
 
Thanks for the thoughts.

We're flying to a convention. Best described as "mini-Oshkosh, ultralight version, in Canada". On dear ole dads bucket list is to fly his own plane, through US airspace to this convention. So this is our year.

So ya, I can't put him in the -7. I know it'll be brutal sitting at 100+knots. It'll be a long haul either way. In a Kitfox or a -7 ready to fall out of the sky:) but I'd rather keep close to pops and keep an eye on him.

I'm going out on Tuesday to see what that feels like. Throttle back, a touch of flaps, lean it out and see.

If it's a no go I may go back to plan A. I'll report back. Thanks again for the input.
 
I've flown an RV-8 at 90kts for "a while" (eg an hour) and comfortably did so without added flaps. If 10 degrees of flaps helps with the view angle, then find a happy medium that suits you.

Go up and fly along side your dad to find what works for both of you. (... and happy Father's Day to all the dad's out there)
 
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CHTs

I've formated with a cub for a while... a slow cub babying his motor, 60-70kts. The -6 was more of a rudder airplane in that configuration, which was fun. I was slightly behind the power curve, and CHTs soon started climbing so I broke out after 20 minutes. Keep an eye on those CHTs! I have 'blocker tape' on both sides, would need to experiment with removing it were I to attempt that mission again.

-jon
 
Ok, just a follow up for those who may be considering what I am.

I flew today for about 2 hours. The plan was to cruise at 2/3rd speed (100 knots vs. 150 knots) and see what that felt like and if the plane was happy or not.

I think the experiment was a success. Here are the findings.

At 40% power, 16.0 MAP and 2200 on the prop I was right in the 100 knot range. I needed about 5-10 degrees of flaps to bring the nose down to a normal attitude. CHT's were perfectly fine. 320 degrees on all cylinders. Oil temp was fine too. It heats up quicker but stays at the 185 degree range or below.

As expected the plane flies a bit mushy but after awhile I got use to it. I found it quite relaxing actually. There is less vibration and it's a bit smoother and just kind of fits in with the whole "chill out and cruise" mindset.

I leaned the engine out to 4.5 gallons per hour. At 3.5 it seemed to run rough so I enrichened it a bit and it smoothened out fine. EGT's were mid 1350's or above but who cares about EGT's at 40% power.

The autopilot held the plane ok but the plane was much more susceptible to up drafts and down drafts. The Autopilot wasn't happy about that as it was trying to maintain altitude with an under producing engine. Smooth air was fine.

As mentioned above, the degree of flap extension made a huge change to the sight profile out the window. A few degrees down and things looked just like normal. No where near 20 degrees was needed as my original post suggested.

Dad and I found it better for him to take off first and clear the zone and then I would get airborne and catch him on our pre-assigned discreet frequency. Then I'd slow things down and cruise.

So there you have it. It's possible. With shortish legs of 2 to 2.5 hours each it'll take awhile but should be managable. As I said before, it's all about Pops and making memories in our planes.

My hope is that I'm not carboning up the engine flying like this? I don't think so because with such low fuel burn there's not too much gas in there? Please share your thoughts on this.

Darren
 
At those power settings lean it as much as you can, until just before roughness sets in. If you can run smoothly LOP, do it.
 
Last weekend I tried following my boys in their Tomahawk (90KT ish). It took a lot of effort, mainly because the Tomahawk was affected much more by changes in wind speed and up/downdrafts than the RV. I kept getting too close to them, and then too far away when I would back off. I was at a high angle of attack, so keeping an eye on them was difficult. This was with full flaps. My conclusion after an hour of hard work: as much as I wanted to hang with them, it was much better and safer to meet them at the destination. Flying around a 90kts does not replicate following another plane at 90kts and trying to stay in visual contact.
As far as running LOP - tried that too, but I kept having to enrich to climb with them in the updrafts. Then you have to re-lean and repeat. This is not set-it-and-forget-it flying. There is no way you can do that for 30 hours. It is like trying to drive in traffic with the cruse control on.
What I did find is that staying in contact on an open frequency was just as good as keeping them in visual contact.
 
Thanks for your thoughts. I didn't even try to keep in visual contact with my Dad. It was way too much work and took way too much brain power.

As long as our altimeters were set to the same pressure and our GPS's were set to the same destination, we just flew our own way. I stayed right of the magenta line, he stayed left, I stayed 3-400 feet above or below and all seemed well. We talked on the discreet freq. and updated our position every 5 min or so. Or just to chat.

Dad did take off first and I would arrive at the destination ahead of him but my whole "slow" flight experiment was so that I didn't get there an hour ahead of him for every two hours flown.

Ya, flying within visual contact with a 90 knoter is a recipe for disaster I think. Short term maybe ok. But long range, no way

Darren
 
Darren, thanks for the write up. It sounds like touve got a good recipe for your father-son trip! From time to time, I fly with a Cherokee 140 at 105kts. I've not tried adding flaps but I may add 5 degrees and see what it does to speed, AoA, and fuel burn. I always lean so I think our respective experiences will be close.

Fly safe!
 
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