For various reasons, I've decided to pull the wheelpants off and go with a larger tire. After looking at several planes at Reklaw with 850s I really like the look, but was wondering if 800s might be a less expensive (both in dollars and weight) alternative while still retaining the look and feel.
My flying is about 60% asphalt, 20% smooth grass and 20% rough grass, dirt or gravel.
Would like to hear from anyone who has flown either or both. I've run 800s on my Tcraft and Citabria, and have run 850s on a TriPacer in the past as well.
I've got several pictures of 170s with 850s, but none with 800s. A link to any pics with 800s would also be appreciated.
As always, thanks for any and all input!
Tire Delimma: 8.50 or 8.00 ?
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Tire Delimma: 8.50 or 8.00 ?
Craig Helm
Graham, TX (KRPH)
2000 RV-4
ex-owner 1956 Cessna 170B N3477D, now CF-DLR
Graham, TX (KRPH)
2000 RV-4
ex-owner 1956 Cessna 170B N3477D, now CF-DLR
8:00 tires
I run 8.00 x 6 6 ply tires on my 170A which is equipped with Cleveland wheels and brakes. I have "spats" rather than full wheel "pants".
Most of my operations are on hard surfaced runways, but it seems to like grass (or bean field stubble) equally well.
I think the slightly higher "stance" makes for easier take offs, but that is only a guess and not based on tests. I have flown a 170B with 6.00 x 6 tires and can't recall any problems on either hard surfaced or grass runways.
Al Culbert N5455C
Most of my operations are on hard surfaced runways, but it seems to like grass (or bean field stubble) equally well.
I think the slightly higher "stance" makes for easier take offs, but that is only a guess and not based on tests. I have flown a 170B with 6.00 x 6 tires and can't recall any problems on either hard surfaced or grass runways.
Al Culbert N5455C
-
Bruce Fenstermacher
- Posts: 10318
- Joined: Tue Apr 23, 2002 11:24 am
Craig
I have 8.00x6 on my 170. I like big tires for the "look" as well. 8.50s when compared side to side are bigger and if that is what your set on go for it. When not seen side by side I think the 8.00s are big enough, are probably cheaper and don't require any approval.
Here is a link to one of my sights that has several pictures of my 170 which show the wheels. The first row middle in particular.
http://mywebpages.comcast.net/tfenster/SJ/SJ.html
I have 8.00x6 on my 170. I like big tires for the "look" as well. 8.50s when compared side to side are bigger and if that is what your set on go for it. When not seen side by side I think the 8.00s are big enough, are probably cheaper and don't require any approval.
Here is a link to one of my sights that has several pictures of my 170 which show the wheels. The first row middle in particular.
http://mywebpages.comcast.net/tfenster/SJ/SJ.html
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
The 800 tire is very versatile and all around good choice. Large enough to handle many unimproved or marginal landing situations, yet not require approval. I have taken mine into places I probably should not have gone, but they always get me back out. Sand and mud are a no-no though. The AK Bushwheel or Gar-Aero is way better at soft situations.
(Picture of me standing on my 800x6 tire)
http://www.c170.com/gallery/Bruces-Photos/Bold
The other Bruce
(Picture of me standing on my 800x6 tire)
http://www.c170.com/gallery/Bruces-Photos/Bold
The other Bruce
Hey Craig,
We have a fellow member that is respected for his short field experience in Idaho. He moved to Idaho from Alaska. Kelly Mahon said that he shortened his take off run by 200 ft, when he installed the 8.50's vs the original 6.00 tires. Angle of Attack! It would be interesting if you tracked your before and after. Glad to have met you this past weekend!
We have a fellow member that is respected for his short field experience in Idaho. He moved to Idaho from Alaska. Kelly Mahon said that he shortened his take off run by 200 ft, when he installed the 8.50's vs the original 6.00 tires. Angle of Attack! It would be interesting if you tracked your before and after. Glad to have met you this past weekend!
-
Jr.CubBuilder
- Posts: 517
- Joined: Thu Aug 12, 2004 10:33 pm
I'll see if I can attach a pic of mine sporting 800s the SC behind it is on 31"s
http://www.backcountrypilot.org/gallery ... fullsize=1
Nope it doesn't seem to want to show up in preview, but the link should work.
http://www.backcountrypilot.org/gallery ... fullsize=1
Nope it doesn't seem to want to show up in preview, but the link should work.
Thanks for all the pics and info guys.
As much as I'd like the 850s, it looks like 800s would be about half the cost, save me a little weight and maybe not have as much speed pentalty. Looks like they'd perform pretty well on the surfaces I'll be landing on too. The plane is too nice to take anywhere truly nasty, so the 800s. should probably do the trick. Now to decide between McCreary 4 plys (which I had on both the Tcraft and 7GCBC) or the Goodyear 6 plys.
As much as I'd like the 850s, it looks like 800s would be about half the cost, save me a little weight and maybe not have as much speed pentalty. Looks like they'd perform pretty well on the surfaces I'll be landing on too. The plane is too nice to take anywhere truly nasty, so the 800s. should probably do the trick. Now to decide between McCreary 4 plys (which I had on both the Tcraft and 7GCBC) or the Goodyear 6 plys.
Craig Helm
Graham, TX (KRPH)
2000 RV-4
ex-owner 1956 Cessna 170B N3477D, now CF-DLR
Graham, TX (KRPH)
2000 RV-4
ex-owner 1956 Cessna 170B N3477D, now CF-DLR
-
zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
I've heard that angle of attack argument before and don't really buy it. Every time I watch a taildragger take off , the airplane starts rolling,the tail comes up and a few seconds later the airplane rotates & lifts off. Haven't seen the tailwheel hit the ground yet.
The exception would be like the short TO contests, where the tail comes up before the airplane starts to roll. Even then, the airplane is rolling on the mains when rotation & lift-off occurs. A super-STOL airplane might rotate hard enough to hit the t/w on the ground-- maybe.
Another exception would be a takeoff from a 3-point attitude. I don't see this too often. I've done it myself but it seems to take just as long or longer than letting the tail come up first.
Eric
The exception would be like the short TO contests, where the tail comes up before the airplane starts to roll. Even then, the airplane is rolling on the mains when rotation & lift-off occurs. A super-STOL airplane might rotate hard enough to hit the t/w on the ground-- maybe.
Another exception would be a takeoff from a 3-point attitude. I don't see this too often. I've done it myself but it seems to take just as long or longer than letting the tail come up first.
Eric
The claim of 8:50's shortening takeoff roll reminds me of the flaps-for-takeoff discussion. If 20 degrees of flaps is "more drag" than a lesser setting ...thereby lengthening takeoff roll...
Then for certain, presenting a greater amount of the entire belly/underwing to the relative wind from the beginning of takeoff roll has got to be worse.
I've flown a takeoff routine or two in which the tail is never allowed to leave the ground until after the mains, by holding the elevator back to keep the tail planted until the plane flys. It never reduced takeoff roll any at all. I was always able to leave the ground in an equal-or-shorter distance by letting the tail rise of it's own accord first, then use slight back-pressure to lift the mains off.
(It's just not going to fly until it's ready. There were many cases similar to this situation during the early days of swept-wing jets. An over-anxious pilot could rotate the aircraft so high/so early in the takeoff roll that the wing would be stalled from early on, and remain stalled the entire takeoff run, such that the aircraft never flew but instead simply ran off the departure end of the runway. A notable early accident just for this reason occurred to a Lockheed JetStar at Chicago's Midway airport.)
Consider the fact that there are 9 ways to rotate an airplane for takeoff...and 8 of them are wrong (because they will lengthen takeoff roll.)
Draw a large tic-tac-toe diagram such as #. That will allow us to depict 3 columns, and 3 rows of possibilities. The columns will represent rotation timing, i.e., column 1 will be "too early", column 2 will be "on time", and column 3 will be "too late".
The rows will represent rotation angle. The bottom row/across the # will represent "too low", the middle row will represent "just right", and the top row will represent "too high" (of an angle of attack.)
In all cases of "too early", the aircraft is presenting unnecessary drag, thereby lengthening takeoff roll. The same can be said of all cases of "too high". In all cases of "too late", unnecessary ground-roll has already passed beneath the aircraft prior to flight. And all cases of "too low" will also allow unnecessary terra-firma to pass beneath the airplane, for lack of sufficient lift.
This means that the only option left us is the very center position column/middle row, representing "on time, just right" amount of rotation angle.
All taildraggers begin their takeoff rolls with rotation being "too early", which means excessive airframe drag, which slows the airraft's acceleration rate. There's nothing we can do about that. I believe that installing taller tires that further raise the angle of attack can only exacerbate the situation...provided that, a greater problem of rough runway doesn't exist that the larger diameter tires alleviated sufficiently to permit faster acceleration rates which might overcome the airframe drag caused by the natural, taildragger stance of early rotation.
(Of course, if you have a runway full of 6" tall bumps in it, each bump will be a "hill to climb" of a small tire, but will be only a bump to a large diameter tire. And that is the primary advantage large diameter tires have over small ones. A secondary advantage is that a larger diameter wheel has less rolling resistance than a small dia. wheel, even on a smooth, hard surface. {The reason I suspect many who convert to the larger tire believe the increased angle of attack makes for shorter takeoffs. In reality, it is most likely the lessened rolling resistance that assisted in the takeoff, not the higher stance.} Conversely, a larger wheel requires more braking capability unless the braking surface (disc-size and/or friction-pad size) is increased. Very large tires approach total defeat for standard brakes, especially while taxying in strong crosswinds.) Taxying downwind can be a real challenge when it comes time to turn the aircraft crosswind. A loss of control or groundloop can occur simply during taxi. This nearly happened to me while on the way home from Reklaw, when Jamie and I stopped for fuel at Center, TX. After fueling, we were taxying downwind for takeoff. It was pretty windy/gusty and as I approached the run-up pad I needed to turn right to the hold-short line at the runway threshold. As I turned right, the wind grabbled the tail and tried to swing it hard towards the left wingtip in a clockwise rotation, just exactly as if someone back there was pushing on my fuselage right side to swing me around in position. My Cleveland brakes on my 6" wheels almost couldn't contain it. I had to apply full, hard left brake to prevent a clockwise groundloop. This occurred even tho' I was taxying very slowly in preparation to making a right hand turn. I'm certain that had the airplane been equipped with larger tires that I would have lost control of the turn.
Like all things aviation, there's a compromise somewhere in the mix. The smaller 6:00 tires are best for most of us in terms of cost, weight, drag, braking efficiency, etc. I think I'd have to really be in rougher country than I'd like to be in my 170 before I'd consider anything larger than 8:00 tires. The cost of a legal conversion and the suitability of the airplane for the terrain would be a concern for me.
Then for certain, presenting a greater amount of the entire belly/underwing to the relative wind from the beginning of takeoff roll has got to be worse.
I've flown a takeoff routine or two in which the tail is never allowed to leave the ground until after the mains, by holding the elevator back to keep the tail planted until the plane flys. It never reduced takeoff roll any at all. I was always able to leave the ground in an equal-or-shorter distance by letting the tail rise of it's own accord first, then use slight back-pressure to lift the mains off.
(It's just not going to fly until it's ready. There were many cases similar to this situation during the early days of swept-wing jets. An over-anxious pilot could rotate the aircraft so high/so early in the takeoff roll that the wing would be stalled from early on, and remain stalled the entire takeoff run, such that the aircraft never flew but instead simply ran off the departure end of the runway. A notable early accident just for this reason occurred to a Lockheed JetStar at Chicago's Midway airport.)
Consider the fact that there are 9 ways to rotate an airplane for takeoff...and 8 of them are wrong (because they will lengthen takeoff roll.)
Draw a large tic-tac-toe diagram such as #. That will allow us to depict 3 columns, and 3 rows of possibilities. The columns will represent rotation timing, i.e., column 1 will be "too early", column 2 will be "on time", and column 3 will be "too late".
The rows will represent rotation angle. The bottom row/across the # will represent "too low", the middle row will represent "just right", and the top row will represent "too high" (of an angle of attack.)
In all cases of "too early", the aircraft is presenting unnecessary drag, thereby lengthening takeoff roll. The same can be said of all cases of "too high". In all cases of "too late", unnecessary ground-roll has already passed beneath the aircraft prior to flight. And all cases of "too low" will also allow unnecessary terra-firma to pass beneath the airplane, for lack of sufficient lift.
This means that the only option left us is the very center position column/middle row, representing "on time, just right" amount of rotation angle.
All taildraggers begin their takeoff rolls with rotation being "too early", which means excessive airframe drag, which slows the airraft's acceleration rate. There's nothing we can do about that. I believe that installing taller tires that further raise the angle of attack can only exacerbate the situation...provided that, a greater problem of rough runway doesn't exist that the larger diameter tires alleviated sufficiently to permit faster acceleration rates which might overcome the airframe drag caused by the natural, taildragger stance of early rotation.
(Of course, if you have a runway full of 6" tall bumps in it, each bump will be a "hill to climb" of a small tire, but will be only a bump to a large diameter tire. And that is the primary advantage large diameter tires have over small ones. A secondary advantage is that a larger diameter wheel has less rolling resistance than a small dia. wheel, even on a smooth, hard surface. {The reason I suspect many who convert to the larger tire believe the increased angle of attack makes for shorter takeoffs. In reality, it is most likely the lessened rolling resistance that assisted in the takeoff, not the higher stance.} Conversely, a larger wheel requires more braking capability unless the braking surface (disc-size and/or friction-pad size) is increased. Very large tires approach total defeat for standard brakes, especially while taxying in strong crosswinds.) Taxying downwind can be a real challenge when it comes time to turn the aircraft crosswind. A loss of control or groundloop can occur simply during taxi. This nearly happened to me while on the way home from Reklaw, when Jamie and I stopped for fuel at Center, TX. After fueling, we were taxying downwind for takeoff. It was pretty windy/gusty and as I approached the run-up pad I needed to turn right to the hold-short line at the runway threshold. As I turned right, the wind grabbled the tail and tried to swing it hard towards the left wingtip in a clockwise rotation, just exactly as if someone back there was pushing on my fuselage right side to swing me around in position. My Cleveland brakes on my 6" wheels almost couldn't contain it. I had to apply full, hard left brake to prevent a clockwise groundloop. This occurred even tho' I was taxying very slowly in preparation to making a right hand turn. I'm certain that had the airplane been equipped with larger tires that I would have lost control of the turn.
Like all things aviation, there's a compromise somewhere in the mix. The smaller 6:00 tires are best for most of us in terms of cost, weight, drag, braking efficiency, etc. I think I'd have to really be in rougher country than I'd like to be in my 170 before I'd consider anything larger than 8:00 tires. The cost of a legal conversion and the suitability of the airplane for the terrain would be a concern for me.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
-
cessna170bdriver
- Posts: 4063
- Joined: Mon Apr 22, 2002 5:13 pm
Yes George, but you are conservative enough with your airplane, that I'm surprised you don't fly it from the right side.gahorn wrote:I think I'd have to really be in rougher country than I'd like to be in my 170 before I'd consider anything larger than 8:00 tires. The cost of a legal conversion and the suitability of the airplane for the terrain would be a concern for me.
(Just couldn't resist). Miles
Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
Finally decided to go with a set of 800x6x6 Goodyears. I've had the McCrearys in the past so I thought I'd try something different. Pulled the wheelpants off last night and hope to get the backing plates and tire swich accomplished sometime this week. Looks kinda naked at the moment, but I'll get used to it. Sure will be nice to be able to check tires/brakes/air without unbolting the pants each time.
Craig Helm
Graham, TX (KRPH)
2000 RV-4
ex-owner 1956 Cessna 170B N3477D, now CF-DLR
Graham, TX (KRPH)
2000 RV-4
ex-owner 1956 Cessna 170B N3477D, now CF-DLR
I check the tires/brakes every 50 hours (second oil change). I check the air by looking up and making a three-hundred-and-sixty degree turn. If I don't see large, dark anvil-shaped clouds...it's good to go!
(On an even goofier note, ... I've noticed that when my Desser Air Classic tires (with diamond tread on the sidewalls) get below the specified 24 psi, that when I taxi around a corner the sidewalls make a "strumming" sound against the wheel fairing scrapers. Sounds like a kid's bicycle with playing cards in the spokes. Tells me it's time to get out the air bottle and tire gauge.)
(On an even goofier note, ... I've noticed that when my Desser Air Classic tires (with diamond tread on the sidewalls) get below the specified 24 psi, that when I taxi around a corner the sidewalls make a "strumming" sound against the wheel fairing scrapers. Sounds like a kid's bicycle with playing cards in the spokes. Tells me it's time to get out the air bottle and tire gauge.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
-
briancbaker
- Posts: 15
- Joined: Thu Aug 18, 2005 10:12 pm
Interesting theorization! Incorrect in this case, but interesting still!
If your airplane is like all other 170’s you will notice that when doing a full stall landing that the tail touches first. This means that the airplane will fly at a greater angle of attack than it sits on the ground. That is an important note.
Compare the angle of attack, stock 170 vs the modified 170 (180 gear & 8.50 tires). Raise the tail of both planes 2 inches, while rolling down the runway. Big difference in the angle of attack! The modified 170 has the option of raising his tail off the runway further, if the pilot wanted to decrease angle of attack to that of the stock. But obviously he wouldn't do this or would drop the tail down, to avoid being forced to develop more speed, therefore extending his roll distance.
STO 102 - Get a model airplane from around the house. Notice that when it rolls up onto one wheel the wing can now reach a greater angle of attack without dragging the tail. This requires the flaps to be pre-set btw. I only mention this to illustrate how important angle of attack is in serious STOL. This takes lots of practice!
Who in the Lower 48 needs STOL capabilities anyway? The author of this post likes the looks of the larger tires. And honestly if it weren’t for looks, wouldn’t we be better with 172’s?
I don’t know what the heck the X-wind turning theory was about!
In Theory - I figure after visiting Ole Gar, just walking a straight line was difficult!
If your airplane is like all other 170’s you will notice that when doing a full stall landing that the tail touches first. This means that the airplane will fly at a greater angle of attack than it sits on the ground. That is an important note.
Compare the angle of attack, stock 170 vs the modified 170 (180 gear & 8.50 tires). Raise the tail of both planes 2 inches, while rolling down the runway. Big difference in the angle of attack! The modified 170 has the option of raising his tail off the runway further, if the pilot wanted to decrease angle of attack to that of the stock. But obviously he wouldn't do this or would drop the tail down, to avoid being forced to develop more speed, therefore extending his roll distance.
STO 102 - Get a model airplane from around the house. Notice that when it rolls up onto one wheel the wing can now reach a greater angle of attack without dragging the tail. This requires the flaps to be pre-set btw.
I only mention this to illustrate how important angle of attack is in serious STOL. This takes lots of practice!Who in the Lower 48 needs STOL capabilities anyway? The author of this post likes the looks of the larger tires. And honestly if it weren’t for looks, wouldn’t we be better with 172’s?
I don’t know what the heck the X-wind turning theory was about!
In Theory - I figure after visiting Ole Gar, just walking a straight line was difficult!