Tip Tanks Effects Upon Speed

[Jim Golden]

OK, I've spent an hour on here searching and came up with zip. So I will ask my question.

Do tip tanks slow the plane down, or speed it up?

My one really good buddy has a father who owns a '52 Bonanza. He put tip tanks on it and it made the plane faster. As an aerospace engineer, that only makes sense to me if the wing had a crummy tip on it and the tip tanks reduced the tip vortices.

It is generally acknowledged that the Comanche has a superior wing to the Bonanza, being a tapered NACA laminar flow 65 series. Being thus, I would expect the tip tanks to slow down the Comanche, especially if equipped with a proper Hoerner type tip. But, I'm not sure that the OEM was a Hoerner style wingtip. In fact, I think it wasn't.

But at any rate, all theory aside, what do the folks who had 60 gallons with stock wingtips say now that they have 90 gallons with the tip tanks installed regarding speeds?

I'm looking at getting a late 250 or 260. The difference being 30 gallons of fuel. I know some folks say 60 is plenty and it's time to land, get out of the thing, stretch out, and have a sandwich. But others I talk to say get the extra 1.5 hour of flight in and get to where you're going...then stretch and get a sandwich. Personally, I like the idea of big tanks and then I can do what I feel like doing.

What have you all that have actually done this experienced? Do the tip tanks slow you down with the big laminar wing? Or, do they speed you up like the Beech Boys with their NACA 5 series turbulent wing?

Thanks!
Jim

[N3322G]

Best speed mod ever becasue you don't have to stop as often for gas.

[Kristin Winter]

The tip tanks also provide an end plate effect which could by positive, especially at altitude. I haven't noticed that tip tank equipped Comanches are slower, but I haven't make a study of it either.

[JIMICS2452]

My 250 with tip tanks seems to run about the same speed as stock 250's I have flown with. I do not think they make much difference in speed. However, in the 250 you get an increase in the gross weight to 3000 pounds which may be used with no restrictions, that is with the tip tanks empty. There is no change in the C.G.

60 gallons is not enough fuel for a 250 being used as a serious cross country machine.

[Matt Bogard]

It's not an extra 1.5 hours of flight, it's an extra 2+ hours at 12.1 GPH at cruise! And as a speed mod, it's a great one because there is no need to stop for gas. Or, better yet, when your destination has expensive gas you can tanker in the fuel for your return trip and now pay $9.15 a gallon at KMDW...

I don't have enough time in a Comanche without tanks to be able to comment, but my plane seems to hit the numbers in the books.

[William Hughes]

I put tip tanks on my 1960 250. I did a lot of cross country before and after, kept good notes, and can't really notice any difference in speed. Except for the having the legs is way faster than stopping for gas.

Also nice for reserve fuel on an IFR leg.

[Jim Golden]

Thank you for the replies, everyone. I was talking with a gent who's modified his 260 so that it cruises now at about 206mph. I'm not sure what it originally cruised at, but I would think about 20mph slower. He said the tip tanks did slow them down....maybe that is true for the 205 mph cruise but it looks like not for the 185 mph cruise.

One of the 250's I'm looking at buying has tip tanks, so that is why I wanted to know. It's an earlier model with the 60 gallon internal tanks. Sounds like they are a good thing.

Thank you again so much for the replies!

Jim

[Ray B]

Jim there is one more advantage to tip tanks not mentioned above, you do not "have" to take that 30 gallons along if you do not need it. 40 years ago my 1st 1,000 hrs of Comanche time was in a budys '59 250 with tip tanks. I then bought a late '62 model 250 with toe brakes, electric flaps and internal aux tanks. The two 15 gal internal bladder tanks had to be kept wet ie topped off even though the trip was only 300 miles. I flew next to Darell's tip tanked 250 many times with 4 aboard in both airplanes on long and short flights. On long hauls like CA to OSH with both topped to 90 gals we were not a mile apart after 5 or 6 hours of flight at 9.5 or 10.5K , both burning 12.3 gal/hr. But on shorter runs of 300miles or so with the tips empty He would be as much as 10 mins. ahead of me since I was lugging an extra 180 lbs and he was to alt. and cruise speed faster. My present 1960 250 with it's 60 gals may not be considered long range any more but at 73 I'm not LR for sure. 3 hrs still puts me 500 miles down the road which equates to 9 or 10 hrs in the car and beats my old PA12 of 50 years ago by a long shot! My optinum Comanch is a '62 250 that still has mechanical flaps/ the hand brake a center stack radio pannel and britten/osborne tip tanks. Ray B

[Richard Muller]

I had over 37 year a PA 24-250, 32 year with Tip-Tanks. With Tip-Tanks, the higher the faster. She goes 150 to 155 kt TAS as a function of the weight in FL 100 and FL 150 but in FL 150 with less fuel -flow.
With Tip-Tanks, the plan is landing smoother.

[Jerry Fitzgerald]

[William Hughes]

That is pretty amazing. I'd like to know what he did!