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[Motorman]

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[John Paris]

MM,
Seems like the math is good.  Now if you have arms that a 4 feet long, you could have been going faster.
John

[Ted Fancher]

Handle to thrust line 52' 6" timed 56 seconds for 8 laps. I'm getting 32 mph but it seemed faster than that. Please check my math.

Thanks,
MM

MM

Nothing wrong with your math.  You went 52% of one mile (I added two feet to your line length to account for your appx arm length) in four seconds less than a minute.  One full mile in one full minute is...hmmmm....a mile a minute...somewhere right around 60 MPH.  Since you only went slightly more than half a mile in slightly less than one full minute a tiny bit over 30 MPH sounds right on the money.

You did realize your basic lap math breaks down to exactly seven seconds a lap don't you.  and on short lines!  Sounds like you've got to get enough flights under your belt to be comfortable flying closer to 4.5 to 5.0 laps.  I'm suspecting you're probably not flying a lot of patterns at your current lap times.

Tell us a little about the airplane and the power train and maybe we can be of some assistance.

Ted Fancher

[Mike Anderson]

Are you sure you zero'd your watch before timing?

[Dane Martin]

Sounds good for duration flying.....

[Dane Martin]

Well off of grass is gonna take some real thought! That probably makes the plane take twice as long to get up to rotation speed and lift off. I wonder what it would feel like in the air "up to speed" with the lead outs slightly forward? What if they could move forward, and turn the tail wheel slightly more in a right turn. That should force the outboard wing to raise with initial movement during launch. Just thinking out loud. But maybe something to draw out for ideas

[bill bischoff]

Why not mount the main LG turned into the circle to counteract the crabbing? Once airborne, the LG become irrelevant.

[Tim Wescott]

Do the rulz say the plane has to be symmetrical?  Does it do any good to make the inboard wing longer (I could see how it might vastly complicate takeoffs, but once you're in the air it would seem that it'd be a good thing).

[Gary Dowler]

Bingo.


This was my first attempt to take off on grass at low power and the new wheels did the trick. The main problem I'm having right now is the plane crabs nose out very badly as soon as it's released. The inboard wing drops down too, almost touching the ground. It needs a 1/4 lap to get up but then it flys straight. I think the line drag steers it straight once it's up to air speed but the line rake is letting it nose out on the take off roll. Is there a fix? I need to add a tail wheel, should I steer it to the left?

Thanks,
MM

This is normal. Regardless of the surface the plane will almost always want to go straight when it's on the ground, and this is only checked by line tension, which will cause the left wing to dip.  It lessens as speed increases. Soon as the tail comes up you should notice a substantial change. Recently when testing a new plane with throttle control I wanted to try just taxiing it around the circle. I ran into this same problem until I understood what was going on. Soon as I let it get a bit faster and just on the mains it was fine.
A 1/4 lap to get airborne is a bit long, but not horrible. How long is the grass? How big are your wheels?  I recently had issues with grass and wheels myself. Solved it by switching from 2.5" to 3" wheels.

[Fredvon4]

Is there some rule about the take off entirely from grass.

I ask cuz some of my 1/2a stuff is hard to launch from stooge ----so I have 10 feet of card board run way and is is slick enough that in the first few feet I gain some line tension....at three feet wide I can Sort Of whip it a bit by the end of the relatively short "run way"

[john e. holliday]

I use a piece of old carpet scrap for a take off strip with or with out a stooge if grass is too high.