170A vs. 170B (short field info)

140pilot · Post by **140pilot** » Fri Mar 25, 2005 3:01 am

I am currently flying a '46 Cessna 140. Would like to upgrade to a C-170. I know some of the differences between the A and B models. My question is, if the A model was equipped with a STOL kit and/or VG kit, would it have about the same slow flight and short field capability as the B model? Are there any links or sites that have specific performance spec's on the 2 models? Thanks for any input. This is a great website!

N1478D · Post by **N1478D** » Fri Mar 25, 2005 4:37 am

Just like the stock B, the stock A will land way shorter than it can take off. Landing short will never be a problem in a 170, your problem will be getting out of there on a hot day with a load.

R COLLINS · Post by **R COLLINS** » Fri Mar 25, 2005 4:50 am

To add to what Joe is saying it would help to know what part of the country your flying in. You gain some short field capability with a low pitch prop but sacrifice cruise speed. Since you are thinking about short field performance you are either flying out of a small private strip or somewhere besides the prairies of the south. Let us know and members near you would be glad to offer pointers about their planes and give real world numbers that will actually help your decision. Randal

Bill Rusk · Post by **Bill Rusk** » Fri Mar 25, 2005 4:00 pm

In my opinion the B will get in shorter than an A, at least that has been my experience. In order to get a short landing you must get slow. E = MV2, ie the energy equals the mass times velocity squared. Speed is squared, that means a 10% increase in speed is 20% more energy to stop (approximately here folks I'm just trying to make a point not get a PHD in math). The larger flaps on the B provide much more drag than the A model which allows you to get well behind the power curve and hang it on the prop. You will be below the power off stall speed crossing the threshold so that when you chop the throttle the airplane will sit down right now, no float whatsoever, dump the flaps and get on the brakes. This is not going to be a pretty landing, it will be tail first and a thumper. Practice will allow you to land with the threshold between the mains and tailwheel. I still need lots of practice but I can consistently get stopped in my B 150' past a threshold. I am aware that this allows no margin for error, but you asked. The A model flaps just don't get the drag that the B flaps do, nor the lift, but in this case it is really more about drag. The stall horn will not be chirping on short final it should be WAILING.
As mentioned, using all these techniques will get you into places where you will need a trailer to get it out, but it gives you more options in an emergency. The B has a better heater also which is a BIG plus if you are up north. The A model should have similer TO performance to a B. The A will be about 5 K cheaper. They are all fine airplanes and fun to fly.

Bill
PS please note the first three words of this post!!!

Post by **GAHorn** » Fri Mar 25, 2005 4:52 pm

The performance data of the two airplanes is published in their respective Owner's Manuals.
The 170A's best landing distance with full flaps is 1755' over a 50' obstacle on a std day. The 170B's full flaps distance is 1145'.
The 170A's best takeoff distance is 1820' under the same conditions.
The 170B's is 1625'.
If you join The Int'l Cessna 170 Assn, you can view these document for free at our Members Only section.
You may join at our home page, or via phone or email. Contact info is also on the home page or headquarters@cessna170.org .
Hope this helps.

Post by **Bruce Fenstermacher** » Fri Mar 25, 2005 5:13 pm

I fly an A and a B on a regular basis (each is a different plane George). as stated before you can land each in places you can't depart from. A good practiced pilot will be able to land the B shorter than the A. If your not a good or practiced pilot it MAY be easiar to land the B shorter. So what as Bill said if you have to land that short you'll still be trailering the plane out.

There have been plenty of discussions here about VGs and other STOL kits and what each may do or not. I any case in my opinion the effect of VGs would be the same for either model on take off and that is they really don't have much effect. For the money a flat pitched prop will do more for you than anything on take off.

As Bill said the biggest difference between all the models is some of the ichanges in heat /defrost found in '53 and after. Then there is the later landing gear some people like.

My advice as before is to find the nicest example regardless of the year including the '48 that has the equipment that best meets the type of flying you do.

zero.one.victor · Post by **zero.one.victor** » Fri Mar 25, 2005 6:02 pm

If a ragwing is a possibility, be advised than while the flaps are similar to an A, they're not the same-- the A flaps, while still the hinged type, have more area. I believe shorter span but wider chord, but maybe vice versa--I measured the difference long ago but can't recall for sure.
I fly a ragwing, and IMHO the A would be better (and a B better yet) for STOL. You can get a ragwing slowed down, the trouble is that the ailerons run short on authority at the slower speeds necessary for STOL operations. I'm uncomfortable with this lack of control authority. I'm told that the rag 170's ailerons are the same as the 120/140, a much smaller airplane with less wingspan. I believe the A's & B's have the same ailerons as each other, which are bigger & more effective than the ragwing's.
Also IMHO, besides maybe landing shorter, I think a B can probably TO a bit shorter than an A. The barndoor flaps add more lift at TO settings than the A's hinged flaps. But the hinged flaps do help some in my experience. I don't have a lot of B time but I do have some in a 150 with the big flaps.
I think the key to STOL flying is mostly piloting ability, and keeping weight to a minimum (airplane, as well as contents). A heavy airplane (rag, A or B-- or any other model for that matter) with an unskilled pilot is a STOL accident waiting to happen. (I'm not talking about anyone here of course

)

Eric

140pilot · Post by **140pilot** » Fri Mar 25, 2005 7:03 pm

Thanks for all the info gang! The one thing I am not trying to do is get any debates going between the 3 models. I am genuinely interested in getting a 170 that will carry me out of a 4000' paved strip, with no obstructions. I do frequent a grass strip that is 1750' with no obstructions as well. I have a family of 4, and would like to do more flying as a family. We live in the upper midwest, so a good heater is a must!. I have heard the gear on the earlier 170's were possibly a little more springy( like my 140's gear). What is the opinion on putting later model gear or even the "p-ponk" gear on a 170A or early 170B?

Post by **GAHorn** » Fri Mar 25, 2005 9:08 pm

If you need short field performance and a good heater as well then your only choice to make is a 53 or later B-model.

Any gear mod is unlikely to be cost effective in my opinion. There's nothing wrong with the early gear. My 2 cents.
The Pponk has been discussed many times in these forums and I suggest you do a "search" routine to read the comments.

Fri Mar 25, 2005 10:29 pm

I have the early gear and have no intentions of changing them out. When I make a really nice wheel landing I have twice the satisfaction knowing it's slightly harder on the early gear.

Going out on a limb here having not seen the 1750 ft strip or your family, I'd say any of the 170 models will work nicely. It's when your strip is half that when it gets dicey.

N1277D · Post by **N1277D** » Fri Mar 25, 2005 11:07 pm

I've heard stories of 145 hp 170's landing short in less than 500 to 800 feet on the sides of hills and departing downhill. Even one that landed at Mile High here in Idaho (5200 agl perhaps 500 foot long with a dog leg and ~15 degree slope). Mile High is PA18 country. A few years ago there were two crashed PA18s there. It can be done in a stock 170, but only under very special conditions.

One guy landed his C145 powered 170 at lower loon creek in Idaho. It is a high altitude 800 foot no go around strip in a narrow canyon. He was very light had quarter tanks and just barely made it. He took off out of there following the river barely hanging on at the stall, even had the rafters on the river worried.

Would they do it again, in their own 170, perhaps under pristine conditions; in someone elses equipment sure they would..

The 180 hp CSP 170s on wheels and skis have been in and out of some Idaho places that even 185s prefer not to go. Mostly because you can see better over the nose on approach and they have a lighter controls.

doug8082a · Post by **doug8082a** » Sat Mar 26, 2005 12:48 am

Ditto Bruce's comments. I operate out of a 3500' paved strip with a 2200' grass strip. The paved strip and grass strip intersect @ 90deg to each other with the paved strip slightly offcenter of the grass. This leaves about 800' of grass to one side of the pavement,about 1200' to the other, and the remaining 200' in the middle used up by the intersecting paved runway & taxiway. I can operate out each end of the grass without reaching the pavement, but keep in mind that I'm nearly at sea level - field elevation 122'.

I have the early gear as well and haven't had any problems.

140pilot · Post by **140pilot** » Sat Mar 26, 2005 3:37 am

We are about 950' above sea level. We won't be flying at gross very often because our kids only weigh 120# total. I would like to find a good 170 to carry 1 adult/ 2 kids. Most of our flying is done within 100 miles of our home base. Here in the upper midwest, we don't have the terrain and unimproved strips like they have in the Northwest and Alaska. Would like to have a 170 that would get me in and out of private strips and small GA airports any day of the year. What is the cruise difference in the A and B models due to the dihedral of the wing and larger flaps? Would prefer to find someone that would like to trade a 170 for a 140!

Post by **GAHorn** » Sat Mar 26, 2005 3:45 am

There is no difference in cruise speeds between the aircraft. (Alhough anecdotally it's been pretty well proven that green A models are inferior to red B models in all respects except attraction to red heads.)

Post by **Bruce Fenstermacher** » Sat Mar 26, 2005 3:49 am

Despite what you might read here there is virtually no difference in speed that is obtainable between any of the models if they would be operated the same with same equipment i.e. tires, wheel pants in rig and so forth.

Some people believe that green paint is faster than red and vice versa.