Take off distance

bret · #1 08-09-2010, 01:18 PM

Does any one know what the average take off distance would be in a 7 with 200 H.P. C.S. prop at 5000 msl at 75 deg. F.

SteinAir · #2 08-09-2010, 02:31 PM

Depends on fuel load, engine RPM and "junk in the trunk", grass/pavement, flaps, pilot technique....but could be anywhere from 200' to 900'. Spin 'em up to 2850-2900 for a few seconds and they will really leap of the ground fast. Takes a whole boatload of rudder, but it's a kick in the rear!

Just my 2 cents and experience with a 200hp, C.S, RV-7 off of Grass.

Cheers,
Stein

bret · #3 08-09-2010, 02:50 PM

200 feet? even at 5,000 ft Ele.

flion · #4 08-09-2010, 03:21 PM

Up here in Flagstaff, a fully loaded -6A (mine) uses 0 runway to get airborne. Ok, we cheat - we have a displaced threshold. However, my nose gear is up almost immediately and the mains are off under 1000 feet. That's even on a hot day (hot up here is around 90F). I'm running a 180 HP IO-360 with CS at 7000' MSL. Being a bit busy on the roll and not having an accurate way to measure, that's the best I can tell you but I wouldn't be surprised if an actual measurement would show 500 to 700 feet. Maybe Brad will chime in with better numbers; he's got more time in an RV than I do.

SteinAir · #5 08-09-2010, 03:47 PM

Quote:

Originally Posted by bret

200 feet? even at 5,000 ft Ele.

Leave the fuel down below half or quarter, get a pilot that is under 200, put down a bit of flap with a gently breeze and the prop screaming and excellent pilot technique, you'd be surprised what these things will do. Naturally I'm assuming a good/light airplane (200hp parallel valve 360 is great for that), composite prop, etc.. If you have a piggy airplane then no-way, but a light RV will do amazing things in the right conditions/hands.

Cheers,
Stein

Mark Albery · #6 08-09-2010, 10:48 PM

For the numbers you give, you have a density altitude of about 6500', so you will have lost 20% of the power/thrust available and will have to accelerate to a 10% higher speed to get airborne. The end result is a take-off run of nearly twice the distance of a comparably configured aircraft at sea-level, standard day conditions.

Van's quote 500' for the gross weight t/o distance for your set up, so 1000' would seem a reasonable guess for your question

jjconstant · #7 08-10-2010, 09:40 AM

Well this is fairly timely. I've just done my first few high altitude takeoffs in my RV7A. Around 6500' DA, 2 people, half fuel, WhirlWind constant speed prop, 190ish HP (mattituck 180 with 9.2:1 pistons). Mid 50's temp, 1rst takeoff was downwind but less than 10kts. No really accurate way of measuring distance but my impressions were:

Downwind takeoff: I always keep the stick back until the nosewheel comes off and then keep the deck angle at the climb attitude. The period of time between when the nosewheel came off and when the mains came off was longer by at least 5 seconds and when I was off I was slow and things were mushy until I lowered the nose BELOW the climb angle and let the speed build. Bitching Betty (AOA) was no where near yelling at me but it was much mushier than normal. My normal takeoff aims for a climb at 110 to 120 kts for cooling. I'm oil temp limited right now.

2nd takeoff was another similar day but upwind in about 12kts. I modified my technique a bit by keeping the nosewheel down until I saw 40 kts then gently moved the stick aft until the nosewheel lifted. The transistion time was back to a more normal "nosewheel is up aaaaaand we're flying!"

On the downwind takeoff my guesstimate for ground roll would be around 1000 -1200' and on the upwind it was much closer to "normal" and would guess around 500 -750' at most.

The deck angle was slightly different for a given airspeed...it seemed that at my normal climb deck angle for 115-120 kts I glanced at the airspeed indicator and was doing 95 kts so keep an easily fooled eye on airspeed not just in landing and takeoff but climb as well.

Bear in mind these are guesstimates by a low time pilot not using good ground references for measuring. I'll try to get better data and report back.

All best

Jeremy Constant
RV7A, around 60hrs

n468ac · #8 08-10-2010, 03:12 PM

Our RV6a will take off in as little as 300 feet, empty, lite on fuel and one on board ... and as much as 1000 feet, with a normal midwest summer day loaded for a trip.

I've had the plane really really loaded, high (around 4000 msl), and hot (100+) ... we took no more than 1500 feet and still made 1000 agl before the end of the 5000 foot runway.

I question is how slow of an airspeed is acceptable to you in the climb and how hot you will let your engine get.