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Landing gear choices...
I am building a 5 and it has the bungee gear. Haven't heard a lot of good things about these gear and am looking to move to either the grove gear or bush gear.
I did a search on TeamKitfox and read through some history but didn't see anything that had a comparison between the Grove and bush gear.
I have read a bit about comparisons of the Grove to bungee gear with the Grove being the "heavy" favorite.
The Grove vs bush gear seems to be similar in the cost department.
I'm wondering about the weight of the bush gear...
I am leaning to the bush gear due to the mounting (looks a bit stronger) and I am thinking it might be a bit lighter.
Looking for some informed opinions...
Regards
Jeff
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Re: Landing gear choices...
I'm a fan of the Grove gear.
On my Yellow plane, when I converted from the standard bungee gear, Douglas wheels, Matco brakes and 20x7x8 atv tires to Grove gear, wheels, double puck brakes and Desser 21/800-6 tires, I had an overall weight gain of only 12 pounds.
I could make that up by skipping a couple double cheese burgers.
(but I probably won't…)
IMO, well worth it. One person's opinion.
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Mark me down as a yes for the Grove gear Jeff. Can't help much with the bush gear reviews. Zero time on those. If you need more prop clearance that may be the way to go and maybe a little lighter weight but you can check those numbers out with the factory but there is no denying the strength, simplicity and popularity of the Grove product on the Kitfox airframe.
Hope you are progressing nicely on your build.
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Good point, Steve. I contacted and spoke directly with Robby Grove when I was building the Mangy Fox to find out if they could make a spring that was taller and still fit and function as originally designed.
They made a spring for me that is approximately 3" taller and 2" wider in stance than the standard model IV spring while still fitting the original mount. The model V spring is already made from thicker and wider material than the IV spring, so I would be surprised if they couldn't do something similar, if you need prop clearance.
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Re: Landing gear choices...
Steve
I have a couple questions in to the factory. With the 340 up front, weight will be a major deciding factor.
I finally finished my panel and have the rest of the engine electronics ready to go in. Headed to the airport today to figure out where everything will go.
I need to get my AP servos so I can get them installed. Will get them next week. After they are in, I should be ready to start covering the fuselage.
The fuel system for my EFII won't work with a 1 gal header so I won't be using a header tank. Gotta run return lines back to both tanks and use a duplex valve.
I was able to sell my Rotax FWF and Kitfox worked with me on piecing together a FWF for my 340. For that I was very grateful. Didn't need everything in the 233 FWF kit. I picked up a set of lift strut fairings too.
At this point is is really just time to start putting things together!
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Thanks for the update Jeff. Keep after it.
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Re: Landing gear choices...
After conferring with other people that like to spend my $$ :D and the folks at Kitfox I have decided to go with the cabane style gear. I do have a question in to Debra about the STi gear tho...
The cabane gear has 3 inches over the Grove style gear. Might need it for prop clearance.
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Re: Landing gear choices...
With your engine that makes sense Jeff and you get that retro look too.
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Re: Landing gear choices...
I have contacted John Roberts at AVWeld and I think he has a pretty elegant solution. Cabane gear with a gas strut that is adjustable! He also uses the spring gear mounts for the forward mount. Price is pretty reasonable too for a shock absorber cabane gear. Here is a couple pics he sent.
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Re: Landing gear choices...
The cabane gear looks nice and the shocks would feel nice, but I really doubt that any of it is a strong as the Grove gear. The Grove is about as indestructible as you will ever find, and if you do bend it (it almost never breaks) just send it back to Grove and they can straighten it and reheat treat it.
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Re: Landing gear choices...
jiott
I understand the loyalty to the Grove gear but drop tests really don't prove the strength of a landing gear. Landing stresses are not a direct upward force. There is a rearward vector force that gets added into the equation. I am not a math geek but the Vans nose gear is a perfect example of this. there's a youtube video that shows a very light (~200 lbs) vector force is all it takes to bend a Vans nose gear enough to throw these planes on their backs. See antisplat.
It would definitely be interesting to do some actual tests to compare the Grove vs cabane gear vector forces but that would require the sacrifice of a few fuselages. We both know that probably won't happen...
That said, the cabane gear is a few inches taller so I am going that route.
Regards
Jeff
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Re: Landing gear choices...
I still stand by my opinion that the Grove gear is stronger in any vector force direction you want, and remember Grove will build you special gear with longer legs. Please take all my comments with the good intentions they are given. I'm not trying to argue or beat you over to my way of thinking, just responding back and forth to your comments. Good luck with your choice.
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No offense taken!
It would be interesting to see an actual real world test though... I spent a couple years in an environmental test lab where we tested equipment of all sorts on shaker tables, drop shock, hammer shock, salt fog, freezing rain, explosive atmosphere, and temps from 150 F to -60 F.
Some of the things you expect to see will surprise you, and some things you don't expect!
Regards
Jeff
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Re: Landing gear choices...
Although not directly related to Kitfox's, here is a good video of Van's landing gear drop tests for their new RV-14 (conventional gear model) and RV-14A (tricycle gear model). It gives one an idea of what conditions should be considered in the design and test of the gear.
https://www.youtube.com/watch?v=KbFM...ature=youtu.be
As a side note, Grove has made an aluminum main gear for the RV-8 for a couple of decades with no problems noted.
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Re: Landing gear choices...
I agree, thorough comparison testing would be great, however I doubt we will ever see it done. In the meantime my opinions are drawn from what I have seen on this forum thru the years and from a little firsthand knowledge. In all cases that I have read about or seen of Kitfox landing gear damage/breakage from hard or bad landings (not counting "crashes" where other major damage occurred) that could not be repaired by some simple rebending, it was always the cabane style with bungees or possibly springs. Haven't seen anything yet on the new monster shock style cabanes. The very few Grove gear damage reports (that I saw) were always some simple bending that looked to me like it wasn't enough of a collapse to drop a wingtip to the ground. Paul Leadabrand at Stick & Rudder has a very high opinion of the Grove gear for his student pilots (including me) who make some very bad landings on many occasions.
Again, this is just my observations over the 6+ years I have been monitoring this site and Kitfoxes in general. I will have to say that it was the Grove gear option that was one of the big factors in my original choice of going with a Kitfox. I very likely do not have a complete story on this and would like to hear from others who have experienced landing gear damage with either Grove or other types. All in the spirit of the title of this thread.
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Re: Landing gear choices...
My only issue with the grove is it's heeeaaaavy:eek:
It's probably 45lbs. Easily the heaviest thing on the plane after the engine.
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The shock Monster gear looks good to me. Anyone know how much lighter it is than the Grove?
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Re: Landing gear choices...
Quote:
Originally Posted by
Esser
My only issue with the grove is it's heeeaaaavy:eek:
It's probably 45lbs. Easily the heaviest thing on the plane after the engine.
After converting my Yellow plane from bungee gear/Douglass-ATV wheels and tires to Grove gear, double puck Grove brakes and Desser 21x800-6 tires the total weight gain (re-doing the weight and balance) was 12 pounds. Well worth it, IMO.
I could cut out the doughnuts and cheezeburgers and get that 12# back, but I probably won't… :rolleyes:
No offense to the choice of the Cabine style gear, but I have seen several planes damaged by not to hard landings with (other than Kitfox made) spring-style cabine gear. The longerons are not meant to take the lateral stress put on them when the spring bottoms out. I have no experience with the Kitfox made gear or with the gas type dampers.
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I had the opportunity to see firsthand a completely destroyed Kitfox IV that went in after an aborted takeoff. The plane crashed nose down right wing low from about 50'. The Grove gear was folded under and ripped from the mounts. It was determined during salvage that the right leg was only slightly bent. I'm now of the opinion that the Grove is 5x overkill strength wise. If one does a lot of really awful hard landings as standard procedure the Grove gear makes perfect sense. It could maybe even be transferred over to a replacement plane at some point :D
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Here's a look at the plane when it was listed with AIG. Click pdf file at top.
htt://www.aigaviation.com/aviationsalvage/SalvagePictures.aspx?FileName=N998DS.pdf&Extension =pdf&Type=p&PictureId=5988
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Re: Landing gear choices...
Grove gear demo yesterday on a very rough surface in central Washington. Cow and wild horse trampled mud dried solid with occasional frost heaved rocks. I won't be landing there anymore! The tires are Desser 850s.
https://www.youtube.com/watch?v=TOaeNlyjeSs
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So has anyone figured out the weight difference between the grove and the Cabana gear?
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Quote:
Originally Posted by
Floog
Grove gear demo yesterday on a very rough surface in central Washington. Cow and wild horse trampled mud dried solid with occasional frost heaved rocks. I won't be landing there anymore! The tires are Desser 850s.
https://www.youtube.com/watch?v=TOaeNlyjeSs
Video doesn't show up. Says it's unavailable. JImChuk
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Re: Landing gear choices...
Quote:
Originally Posted by
redbowen
So has anyone figured out the weight difference between the grove and the Cabana gear?
Or, the cruise speed difference?
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Re: Landing gear choices...
Quote:
Originally Posted by
littlecricket
Or, the cruise speed difference?
Following up:
Asking around, the factory says 3-5mph, Trent Palmer in one of his videos says 10mph, and talking to one another owner says 6-9 mph.
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Cabane and bush gear are the same gear, right?
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I agree that the Grove aluminum spring gear is tough and works well on our planes.
But, I feel a need to defend the 4130 steel tube cabane style gear;
- The cabane style steel tube gear has been used very successfully on many, many Super Cubs, Huskies, Maules etc, for decades in some of the most demanding environments of some of the most extreme places on our planet.
- I know it is a matter of preference, but I think the cabane gear is what looks right on the Kitfox airframe. Lets face it, the Kitfox looks more like an antique airplane than it does a more modern aircraft (like a Cessna). I think Trents' FreedomFox is a really good example of what I am talking about. In his early videos he had the aluminum spring gear. But now with the Kitfox STI cabane gear sitting nice and tall with the large bush tires that Model 5 is an especially impressive looking airplane. In my opinion, it looks "just right" with that STI cabane gear on it. Oh, and it obviously works as good as it looks.
- I have heard of a few Kitfoxes that buckled their cabane style gear in a very hard landing and/or crash. Most gears won't handle those situations. But if you knew you are probably going to be hard on a gear (or you just want some additional insurance), buy a cabane style gear that is purposely overbuilt for bush flying, like the STI or Shock Monster gear. It will be a lot sturdier than the original gear and therefore much more likely to handle heavier loads. And likely still lighter weight than the aluminum spring gear.
- I believe the cruise speed difference is not going to be significant if you make an effort to fair out the cabane gear, and put on similar sized tires as the plane with the spring gear. Granted, most people that want big tires and operate in the bush are more interested in operating in the rough more than speed, so seldom do people take the time to streamline a cabane gear. But if they would I think they'd be surprised how much speed they would get back. (as an example, I have a Highlander that had a standard cabane style gear that was open tube. I replaced that gear with a much taller, bigger cabane gear but covered it with fabric and gained nearly 10 mph in cruise over the non fabric covered gear).
Again, I know the aluminum spring gears work well. But so will the cabane style gear if you pick the right one.
But hey, these are experimental aircraft that we build, so choose the gear that is right for you...
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jmodguy - for what it is worth, I ordered my kit with the cabane gear and that decision was based entirely on looks!! (Glad I didn't read this discussion before hand; too many good, technical or experiential points to be considered and my beer supply isn't sized for that.)
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Re: Landing gear choices...
Grove gear sorta testimonial:
Two of us big people in a K-IV landing at Hemet here in SoCal. Pilot flared perfectly, about six to eight feet above the asphalt. I suggested adding a wee bit of power, but too late. Fortunately we dropped straight down and were tail low when the bottom dropped out. Yes we hit hard, but the Grove gear sucked it up, fortunately not so much as to make the prop hit, but enough to permanently bow the center section so the wheels were splayed about 6-10" and one leg was twisted about five degrees. As said before here, Robbie bent it back into shape and re-heat treated it; good as new.
That said, I never liked the softness of the Grove gear when noodling about on the ground. I like the gears that top out and make the lateral roll relatively rigid, typically the bungee or the cabane.
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Quoted from Av8rPS post.
- The cabane style steel tube gear has been used very successfully on many, many Super Cubs, Huskies, Maules etc, for decades in some of the most demanding environments of some of the most extreme places on our planet.
Cub gear is of a different design than what has been marketed to the Avid/Kitfox group. It is made much heavier (for a heavier aircraft) and the geometry is different.
- I know it is a matter of preference, but I think the cabane gear is what looks right on the Kitfox airframe. Lets face it, the Kitfox looks more like an antique airplane than it does a more modern aircraft (like a Cessna). I think Trents' FreedomFox is a really good example of what I am talking about. In his early videos he had the aluminum spring gear. But now with the Kitfox STI cabane gear sitting nice and tall with the large bush tires that Model 5 is an especially impressive looking airplane. In my opinion, it looks "just right" with that STI cabane gear on it. Oh, and it obviously works as good as it looks.
No one can not argue with this.
- I have heard of a few Kitfoxes that buckled their cabane style gear in a very hard landing and/or crash. Most gears won't handle those situations. But if you knew you are probably going to be hard on a gear (or you just want some additional insurance), buy a cabane style gear that is purposely overbuilt for bush flying, like the STI or Shock Monster gear. It will be a lot sturdier than the original gear and therefore much more likely to handle heavier loads. And likely still lighter weight than the aluminum spring gear.
I can list at least four Avid/Kitfox aircraft that have been damaged by Cabine gear of various manufacturers. Some with landings that I would not classify anywhere near "hard". They all have one thing in common: Very heavy Die-Springs for suspension. This gear design should not be used as "bush" gear. It will damage your airplane in the rough and maybe even on a nice grass strip.
- I believe the cruise speed difference is not going to be significant ...
The little white Sputzy Avid/Kitfox in Merrill showed a significant loss of drag going from Cabine to Grove. His cruise speed increased 10+ mph. Faring of the cabine system would help, but it is difficult to do and no kits are available to install.
Again, I know the aluminum spring gears work well. But so will the cabane style gear if you pick the right one.
That is a very important point. Cabine gear can work very well if done correctly. Look at Trent Palmer's plane or the Factory STi demonstrator. These both have the very effective (and expensive) hydraulic dampers instead of springs. IMO the main problem with the design is the use of the heavy Die-Springs and the very limited travel to a hard bottoming stop. Larger tires will help alleviate this.
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Larry, those are some really good points, and well taken.
For the record, I've always hated the early landing gear design used on Avids and Kitfoxes where they wrap bungees around the bottom of the seat truss. It should have been modified early on to the style of cabane gear like is used on the Super Cub (fyi -the Highlander put the right design on from the word go and has had virtually no issues, and it has been tested extensively by guys like S. Henry). Unfortunately it took the aftermarket companies, and the McBeans STI design to finally provide owners a better cabane style gear for the Kitfox.
And I do agree that even with a good cabane style design, unless you use a gas / hydraulic suspension option, springs or bungees just return any excessive energy into the next bounce. But again, the most commonly used gear in the bush world has used bungee cord forever.
So back to the spring gear. Yes, it is a much easier option to the whole issue overall, but when we talk about absorbing excessive bounce energy, the spring gear has no ability to use a gas shock. So from that perspective the cabane style gear is advantageous.
Of course the cabane style and spring gears have both been used sucessfully for decades, so a lot of this is probably just over analysis to most. So it really is a persons preference. I'm just happy that we now have so many good choices to pick from.
Oh, and I have to admit I'm impressed that Dave gained 10 mph by going to a spring gear. Was his previous gear uncovered? I don't lose 10 mph when I put floats on.
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This is the original gear Dave had on Sputzee.
Attachment 15087
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Hmmm? Well, I guess that is proof positive of what drag a gear design like that can have. Do you have a pic of his plane with the new gear for comparison?
I know my Highlander gear always makes me think I need to do something with the center cross tubes as they are just round tubes like the ones in the picture, so are huge drag all by themselves. And the bungee cord covers are just vinyl so aerodynamic covers would be good there too.
Or I suppose I could just put a spring gear on it and call it good ;)
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Not the best angle, but...
Attachment 15089
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Thanks Larry. Those two pics do a good job of showing the difference between the two styles of gear. And just looking at them both it is quite obvious how the spring gear is cleaner aerodynamically.
Of course, I'm used to a set of floats hanging down underneath my plane. So anytime I fly without them my plane feels like a rocketship, regardless of how big the tires or what kind of a gear ;)
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Hi
I am building a KF5 and have been reading a lot of post on the landing gear option and I am leaning towards the Cabane/Roberts style spring or preferably shock landing gear. I have no problem fabricating my own but do not want to try to do it from scratch with no plans. Are there plans available to purchase and build your own gear?
Joe
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Kitfox Aircraft has a newer "Bush Gear" that is not in their catalog. Check with them for more information.
Ralph
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I just want to put in my 2 bits, there are 3 important factors of the cabane gear 1) Front Down tubes should be 1.25" not 1" 2) Die springs are not a good idea mainly due to short travel 3) A cross tube should be used between the mounts of the cabane"V"
That said here is were I am coming from: I built my Cabane gear I used 1.25" for front tubes, used a longer travel die spring enclosed in a hydraulic dampener IE: Bearhawk design, did not use a cross tube for the Cabane "V"
I did a poor landing to a steep hill and hit HARD No damage to the gear but major damage to the Fuse Longeron twisting and buckling diagonal tubes.
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Is it possible the front tube of the gear was originally sized at 1" so that it would bend before the fuselage gets damaged? (Easier to replace gear legs than a fuselage...)
Your gear sounds interesting. Pics?
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The tube does not bend it folds and props hit the ground and it's a bad day. It was not easy to fix the fuse but I did not have to replace the prop or engine mount or .... Don't know for sure but that is why I think the horizontal tube at the top of the cabane V may have saved the fuse. The geometry of the gear mounts on the fuse are not correct for a cabane style gear and causes a twisting moment on the longerons. If you look at cub mount tabs you see the gear leg is inline with the center of the longerons.
I will see if I can find some pics to post.