I am in current design phase of a biplane. All previous design experience has been with tricycle gear on monoplanes. I have been trying to find out why there are mostly tail draggers for biplanes and very few tricycle setups. Any comments would be appreciated.

Thanks for the help,

EDIT: Feel free to add and questions comments on heavy lifting.

Tyler

Because trike gear on a biplane is just..... just..... well, just.....

WRONG



The only one in the full sized world that I know of is a Waco Cabin Special or something with a lot of odd letters. And it just looks odd.

Conventional isn't all that hard. I've flown both and conventional is actually easier in some cases. The cross wind takeoffs are just a bit harder than trike. And there's a few tricks to setting the toe in and stuff that you can do later if the ground handling is a problem.

Oh come on. Ignoring the asthetics, is there any reason why a biplane can't have tricycle gear? Personally, I say go for the trike gear. Better ground handling, better crosswind, and easier landings.

If you really want to get wild, how about retractable tricycle gear? Just be sure to post a few pictures.

No reason at all. But you can bet the fashion police will shut down his flying field and all the people that saw it will need to go for special counseling....

I know, I know, so call me prejudiced but in my book biplanes just need to sit with their noses in the air.

I'm with you on this one Bruce. A nose gear on a bipe would look like a training bra on Dolly Parton. Just plain silly.

I think there was a model bipe called a Bolero or something like that, can't remember who designed it but it was sold for a number of years that had a trike gear. I always though it looked pretty good.

Several years ago a bipe was flown at the RC world aerobatic champs by Tony Frankelwitz (please excuse the spelling) but I can't remember if it had a trike gear or not.

Most bipes are indeed built as scale models of full scale which use the conventional gear because it works good enough and is lighter than a 3 wheel gear. A nose gear to take any loads needs to be heavier than a tail wheel.

If there were a lot of ground handling maneuvers in pattern flying and a pattern that needed the qualities of a biplane you would see a lot more trike bipes.

Thanks for the input.

Main reason for designing a biplane is for maximum lift on a small wingspan. I'm trying to get a 13kg lift out of 183cm wingspan.

From what I have seen conventional gear landings can be difficult with heavy loads.

I am not sure how heavy loads will work with conventional gear, stearing could be difficult on takeoff.

Asthetics are not a problem, as funtionality is 1st priority on this plane.

I'm not even sure where I would mount trike gear on a biplane, very little documentation on it?

--------------- I am not sure how heavy loads will work with conventional gear, stearing could be difficult on takeoff. -------------

With conventional gear regardless of weight because the CG of the airplane is aft of the wheel contact with the ground it becomes an unstable system. As the airplane is rolling it hits a bump which offsets the CG from the centerline and it tends to want to keep on going. The tail wheel helps stop this until there is a transistion where the tail wheel is not providing much steering and the tail is not providing much aero help.

When the motor is adequately powerful it can literally blast stability into the system through a thrust vector and the vertical tail. Of course the bigger motor brings torque problems with it.

With a heavy airplane the problem comes with the increased moments of inertia in yaw. Once the airplane starts yawing it takes a lot of directional stability to stop it. You tend to over correct and end up with a ground loop. Again lots of power and directional stability will help keep it going straight.

Trike gear is stable. When you get the airplane moving and a little ground bump hits a wheel the inertia of the CG tends to straighten the airplane out.

------------- Asthetics are not a problem, as funtionality is 1st priority on this plane.

I'm not even sure where I would mount trike gear on a biplane, very little documentation on it? --------------

Look at any trike geared airplane and copy it :-) My main approach.

The main wheels are perhaps 5 percent of the wing chord aft of the CG. Too far aft will make it difficult to rotate to take off attitude. Too far forward will not let the nose gear have enough weight on it to allow steering to occur. The nose gear should be located basically as far forward as structure allows. It allows steering with small side loads, something good for large airplanes but not a problem with models.

You want to allow enough clearance with the aft fuselage to allow rotation to the takeoff angles needed. There is a weight lifting contest held every year that some others may know about, I don't remember the name of it. Sometimes the tail cones are slanted upwards to 20 degrees to allow rotation of the wing. Conventional gear setups in this application can't rotate too far so the wings have to be set at a large angle with respect to the fuselage.

Weight lifting airplanes should probably go with a tricycle gear.

Was this any help???

If you're trying to lift a heavy load with limited wing span be sure to watch out for the interplance spacing. For best performance they need to be something like 1 1/4 to 1 1/2 chord widths apart to minimise interferance between the airflows which will dampen the lift. Many of the racing biplanes of the 30's ignored this as a tradeoff for speed but they didn't much worry about higher landing speeds as long as they were tolerable.

And don't let my ragging about aesthetics put you off. It's YOUR model and YOUR hobby. I was just pulling your leg. Do what you want and enjoy it.

Sounds like this is meant for a weight lifting contest. Yes? If so then there are options for the interplane struts to be placed at the tips of the wing panels and act as fences to control tip loses.

Ben,

I thank you for the comments, great help. I will continue with trike design. You have confirmed my theories for take off with conventional setups being unstable especially having a small engine.

BMatthews,

I have current design plans as you mentioned. 1 1/4 chord spacing, and wing tips. It is a weight lifting competition.

Thanks again,

Tyler

You are having all the fun. They didn't have this kind of thing when I was a kid. Well yeah they did, it was the old PAA .049 powered cargo event. There were some great models designed for it. I think Model Aviation or one of the magazines had coverage of a recent lifting contest a few issues ago.

The resulting airplanes are just plain homely. It is a great technicial challenge though. As Bruce said the lift goodness from the big end plate on the bidplane has got to be a lot. Plus some structural difficulties are made much easier. Be sure and make something that can fly well in addition to carrying weight.

Be sure and post a photo of the final result.

HEY ZWEI ! What are you guys smokin up there ? Tri-Gear on a bipe would be uglier than home made sin !

I'm involved with a British version of the American weightlifting comp, which latter is run by the SAE.

In seven years of competition, we have never had a biplane entry owing to the comparatively poor aerodynamics.

However, we have found the trike to be a far superior animal to the conventional u/c, especially as the weight piles on. However, don't fit a spindly bit of piano wire and hope that this will do the trick. You need to engineer the nose-leg or you will find that it collapses and/or renders the model impossible to control on the ground.

BTW, there have been quite a few full-sized aircraft with tricycle gear, I think , especially in the microlight world. Once you become accustomed to the aesthetics, you'll find that they look fine.

Springer

I had forgotten who put the competition on. I guess using a bipe or not would depend if there were wing span limits imposed in the design rules. There would be a set of aero tradeoffs that can be made based on the rules that should give a very clear design trend.

http://www.sae.org/students/ade99res.htm

is a picture of the open class winner. Four motors and lots of propwash will help. The aero layout is a perfect example of the ideal planform for the contest. Note the really big vertical tail to keep the nose going straight. They are ugly. I remember seeing somewhere the standard class had a one motor limit imposed.

To get more variation in the designs they need to make them fit into a box of a given size. It would get rid of that ridiculous tail boom angle.

http://www.db.erau.edu/campus/depart...ontest_98.html

http://home.cfl.rr.com/saeaeroeast/

Just so everyone's familiar with the competition rules, the SAE Aerodesign West states that the model airplane must be powered by a stock OS 61, must have a minimum of 300 cu.in contigious rectangular cargo area (we've been trying to get them to clarify this for the last three years), and a maximum span of 6 feet. There's some others, but those are the important ones.

Zwei, is this your first year competing? If it is, you should be aware that the place they hold the competition for the western region is Palmdale, which is FREAKIN WINDY!! Last year, we had 15 - 25 mph wind. And when I say 15 mph, I mean that's the LOWEST it ever got. And that's not considered to be unordinary during the spring. There were some planes last year that could take off fine, but they were so draggy they could not penetrate into the wind at all.

Ben, yeah, the planes are kinda ugly. But hey, let's see a Extra 300 or a scale P-51 take off with 5 times it's own weight within 200 feet.

Ah, go all the way and install quad gear as some of the early biplanes, triplanes ,etc. had but I don't think the nose wheels were steerable. Extra wheels just kept bad things from happening! Probably the reason you don't see model bipes with tri-gear is that the models copy the biggies and the natural design evolution for bipes through the 20's and 30's was the taildrager designed for rough grass fields which would have been hell on a nose wheel? Claude McCullough had a scale bipe with a nose wheel which I have a pic. of someplace in all my misfiled clutter. "Someones air car" was the name, I believe?

Surprising no one before flicka5 mentioned the primary criteria for choosing conventional or tricycle gear, when the design is open.

I was reminded twice recently that tail draggers steer poorly on paved runways, and trike gear steers poorly on grass or rough fields. I took my M2-E tail dragger to the local flying field on the runway at the now-closed El Toro Marine Air Station. Before that I had been flying it at a local park, off grass/dirt that is patchy and uneven.

On grass it's steers straight on takeoff and landing. On the pavement my first roll out resulted in the plane yawing from side to side. I changed the rudder to low rate, and that helped avoid over-correcting, but the difference was quite obvious.

My newest plane has tricycle gear (I couldn't help it; it was inspired by an ARF!). It doesn't steer well on the grass. Every pebble or bump the nose-wheel encounters results in a new direction. I just try to get it off the ground as soon as possible.

I'm sure that when I have a chance to take it down to El Toro it will track straight as a die on the pavement.

Daniel; The SAE weight-lifting contest was held at Mile Square Park in Orange County, California, in times past, before it was converted to a golf course.

The rules as I recall were based on a maximum plan-form area, and I wonder if biplanes would be allowed, since that would achieve more wing area within a given outline. I can see sesqueplanes coming soon.

Now that Orange County has a new model field at El Toro (with mile-long runways!), SAE should move out of the desert, and back to the coastal area where the weather is better, the air is more moist (more lift), and more spectators are nearby.

Do you know who is the sponsoring club in Palmdale?

Click on the link below for the official rules, from SAE. You'll need the Adobe Acrobat (TM) viewer. It's a free download from adobe.com.

http://www.sae.org/students/aerorules.pdf

Ralph, you're right, it used to be each plane could only have a maximum of 1200 sq. in. of planform; in the case of bi and tri- planes the planform area of each wing was counted. However, this year they changed it to a maximum span (6 ft) with no planform restrictions.

God, I would love it if SAE moved back to Orange County, or go back to Seattle. Really, just as long as they got it out of Palmdale. It's tough enough lifting 25 pounds with .61 cu in of engine, they want us to do it in the desert in the middle of June! With the wind blasting us at 20 mph while shifting through 180 degrees!

Anyways, enough whining. Tailwinds AVS (ADS, some acronym) is the hosting field, and Lockheed sponsers the competition, provides judges, extra help, etc. We're pretty sure Lockheed is the reason SAE keeps having it in Palmdale.

The Claude McCullough scale model bipe that I mentioned above with the trigear was the Wynn
Air Car I believe from a foggy memory. Still haven't been able to find the pic. of it in all the clutter!

The more replies I sent the closer I got to what my memory said was out there! Hey, it was the Gwinn Aircar I was thinking of which was a bipe with tri-gear. Ain't she pretty! UGH!

Sure you can do a trike bipe.

Phil Kraft did it years ago. RCM has the plan, no.pl-133.

Here it is.

And yes, it's ugly.

The Kraft model isn't bad but that Gwinn..... oh my......

If it was an area limited event then mono would be the way but with a span limit the biplane could be a possible winner here.

The high winds would mean that the model may not do well with the end plate interplane panels but then again it might.

I think I'd be tempted to keep the thrust line centered between the wings and the cargo bay between the thrust line and the lower wing. Keep the CG a touch low in otherwords but not TOO low or other oscillation factors may enter into the mix.


Because of the massive wing area of as much as 2000 sq inches I'd be careful about using the super high lift airfoils such as the Selig 1233. You'd have to check the charts and crunch the numbers but with the massive amount of area you'll have I suspect you'd be better off with a slightly lower lift and lower drag airfoil. Bipes are pretty draggy anyway. And if it's that windy there then a little extra speed would be a very good thing anyway.

Tyler; Place the lower wing close to the ground, for extra lift, and with reverse stagger greater than one chord you can do without any decalage.

Vertical separation should also be more than one chord, to minimize interference. Think more along the lines of a tandem-wing arrangement, rather than a conventional biplane. Place the cargo bay between the wings, and make the aft wing larger to assure positive pitch stability. Then, when does a biplane become a canard? Which is a Quickie?

Wait a minute; isn't this a student competition? Forget all the stuff you've read here.

Wow!

I never thought I would get so many replies with such a simple question. Forums are getting to be the best way to find information.

Hopefully in the next week or two I can get my final design plans and drawings done. If construction starts off smoothly I intend to enter the AeroWest SAE competition.

I have had two planes crash in the desert at Palmdale, so I know how bad the wind gets!

I originally designed a tandem wing plane, but quickly realized that someone has to fly it, which I have never seen anybody try. Bipe seemed close enough to me.

It is a student competition. Don't worry about breaking the rules, unless a non student were to do the actual design or building work. I only gain knowledge through this forum which may or may not help in the design.

I will definately post pictures of the plane once complete after the competition.