Do speed mods = increased fuel economy?

[JimG.]

When I upgraded the panel on my M–35 I had to install a new speed slope windshield to get everything to fit.

The new windshield gave me another 7–8 mph.

I gave most of it back when I put vortex generators on the wings and tail.

 

[Jay Honeck]

The Pathfinder I just sold had $20,000 worth of speed mods on it. Basically every legal speed mod available for the Cherokee line.

It got us maybe 9 knots over the stock Pathfinder. Totally stupid, although I always had fun running away from Arrows and early Mooneys. I would certainly have never installed them, nor would I recommend that anyone install anything other than the Fancy Pants. They give you most of the bang for your buck.

And, no, I didn't get any of their value out in resale. People don't buy Pathfinders for speed, they buy them to haul STUFF.

 

[Ken Ibold]

Lance?

Did a pre buy on one (rejected the plane for numerous reasons) and boy howdy! You would have to save a hell of a lot of fuel to make up for the extra time involved with that cowl at every annual.

Contrast that with the ones on our Seneca that are a breeze.

I had a Lance that had that sucker. Whenever I took it in for any mx I would show up with my electric screwdriver, just to make sure the mechanic would not pretend to be out. And it did next to squat in terms of cruise speed, maybe 3 knots. It was on the plane when I bought it. So glad I didn't shell out the $20K+ on it. It did have one nice thing in that it had a cowl flap, so those slow, heavy climbs in the Florida summer were a little friendlier to the engine.

 

[Jaybird180]

The Pathfinder I just sold had $20,000 worth of speed mods on it. Basically every legal speed mod available for the Cherokee line.

It got us maybe 9 knots over the stock Pathfinder. Totally stupid, although I always had fun running away from Arrows and early Mooneys. I would certainly have never installed them, nor would I recommend that anyone install anything other than the Fancy Pants. They give you most of the bang for your buck.

And, no, I didn't get any of their value out in resale. People don't buy Pathfinders for speed, they buy them to haul STUFF.

Time to change the signature block

 

[Jay Honeck]

Time to change the signature block

To...?

 

[DavidWhite]

My Mooney has a lot of the lesser speed mods on it (aileron hinge covers, aileron gap seals) and it DOES make a difference - albeit not a huge one. I can do 160kts at 10gph or 145 at 8.5

 

[Tom-D]

For those who do not believe less profile drag equals faster on the same power should study aerodynamics a little.

Compare a 150 horse power longEZ to a 150 horse power C-172 see which gets better fuel economy.

Speed mods? it's simply a matter of which one works, and which don't.

 

[dmspilot]

The 180E model (1971-72?), I believe was still a hershey wing with the original 30' wingspan.

If it ends in a 0 it's a hershey bar wing. The tapered wing models end in 1. Thus PA28-180 vs. PA28-181.

 

[Graueradler]

The 150 HP Cherokees can get pretty interesting on take off on a hot day. Does it get hot in Texas? Drag reduction mods aren't just for increasing top speed. They also reduce drag at Vy. The reduced power required to maintain Vy makes more power available for climb. Going up 10 HP with higher compression pistons when the engine is overhauled and the pipermods.com prop tip mod (effectively another 10HP from prop efficiency increase) are two of the most effective mods for increasing take off and climb performance of the Cherokee 140. Aileron gap seals increase the low speed controlability feel. I don't know how to measure that so I'm not sure that it is real. I would definitely not repeat the Art Mattson gap seal mod. It is 3M tape on top of the wing and on top of the trim gap in the stabilator. The tape deteriorated, even when the plane hangared and if not changed out in time, doesn't have the strength to be pulled off and still covers and protects the adhesive to prevent solvents from getting to it. If you have the mod on a plane, be sure and replace the tape before it gets too old.

 

[Ken Ibold]

Speed mods? it's simply a matter of which one works, and which don't.

Well that's really the trick question. The problem is finding out for sure whether they work BEFORE dropping the coin on them, rather than trusting the claims of the manufacturers (which tend to be ... optimistic). Unfortunately, many of the people who do the mods don't have good "before" performance numbers, and so tend to overstate the benefit to justify the expense. And those who buy planes with the mods already installed have no way of knowing what the "before" numbers were at all.

I think the other issue is that people will put X number of speed mods on a plane, thinking the incremental gains of each will be additive, when that is seldom the case.

Sure, there are some excellent speed mods for some aircraft. But too many are marketed for "speed", when really the speed gains are marginal and they are really just look-cool customization of your ride.

 

[Norman]

I had a Lance that had that sucker. Whenever I took it in for any mx I would show up with my electric screwdriver, just to make sure the mechanic would not pretend to be out. And it did next to squat in terms of cruise speed, maybe 3 knots. It was on the plane when I bought it. So glad I didn't shell out the $20K+ on it. It did have one nice thing in that it had a cowl flap, so those slow, heavy climbs in the Florida summer were a little friendlier to the engine.

Nobody in our shop wanted to work on that one because the cowl was such a PITA. Too darn many screws. Why LoPresti designed it that way is beyond me. Would have made more sense to split it in the normal top/bottom configuration.