Won't go airborne!!! (Full Version)

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Captain Solo -> Won't go airborne!!! (7/14/2003 7:18:19 AM)

Hello all. I have been a lurker here for a while and have a problem to ask about. I equipped my Flitecraft Solo with 33" Gee Bee floats, and it won't leave the water! I'm going to post some detailed pics below for your comments please. Here is my setup:

Flitecraft Solo:
- 36" Fuselage Length
- Weight: 6 lbs.
- O.S. .46 LA
- 11x6 or 10x7 Master Airscrew Prop
- 1 water rudder
- CG is a quarter inch forward of the front float leg

What I am experiencing:
- I am picking up some very high speeds on the water surface, but it won't lift off.
- At these high speeds the plane predominantly sits back on the rear half of the floats, creating a bit of a water loop.
- Forward of the step, water is splashing directly into the prop.
- I left air once for about five feet and it made an involuntary right roll back down into the water.

I obviously have an issue with catching too much drag from water on the floats. I may need the shorter 28" floats, or even a float that sits higher on the water. I have thought about filling the float half way with liquid expandable foam to improve the ballast.

Here are the pics, please let me know any suggestions you may have... I want to get airborne fast! Thanks!

[img]http://www.tgwebworks.net/webimages/solo_top_water.jpg[/img]

[img]http://www.tgwebworks.net/webimages/solo_side_water.jpg[/img]

[img]http://www.tgwebworks.net/webimages/solo_side.jpg[/img]

[img]http://www.tgwebworks.net/webimages/solo_close_water.jpg[/img]



Wayne22 -> Won't go airborne!!! (7/14/2003 8:31:38 AM)

you can CA or epoxy some plastic or 1/32 ply strips vertically on the inside edge of the floats (at the front) to keep some of the water spray out of the prop. When that happens, it really robs the power from the engine.

Judging from the pictures, the top of the floats appear to be parallel to the bottom of the wing. If you put a spacer, say 1/4" under the front strut to lift the nose up a bit, it will help the wing generate the lift needed to get off the water, and, as a side benefit, raise the prop up out of the water spray. There is some other stuff as well, but try the simple things first...

Both cross braces are bent. Make sure your floats are parallel to the fuselage.

Good luck



Captain Solo -> Won't go airborne!!! (7/14/2003 9:25:39 AM)

[QUOTE]Originally posted by Nony
If you put a spacer, say 1/4" under the front strut to lift the nose up a bit, it will help the wing generate the lift needed to get off the water, and, as a side benefit, raise the prop up out of the water spray. [/QUOTE]

Why on earth didn't I think of that? Thanks! Keep giving me more suggestions please!



seaplane -> Won't go airborne!!! (7/14/2003 5:50:09 PM)

You said the plane does achieve high speed on the water and the floats are sitting on the rear half of the floats. At this stage, the rear half should be out of the water with the floats riding on the step. You didn't describe the surface of the water. If the surface was as smoothe as glass, you may have a problem breaking loose. Full scale float planes will have the same problem. I assume it's the surface tension of the water. One way to fix this is to taxi around creating some waves, then take off through them. You can also rock your ailerons a little to try to get one float at time to break loose. Did you recheck your CG after mounting your floats? You may need to rebalance. From the pics I wouldn't change the length, but I would go with a different brand. The step on the Gee Bee's is not square to the centerline which creates problems........Seaplane



Captain Solo -> Won't go airborne!!! (7/14/2003 6:34:30 PM)

The CG is marked with the floats on. The water is smooth as glass, and I have no way to do anything but taxi a couple of wakes to break it up. Somebody said something in another thread about building up the step square by using epoxy. I'll have to look into your guys' suggestions. Please keep bringing on the help, Solo.



FLYBOY -> Won't go airborne!!! (7/15/2003 2:13:16 AM)

The ply to the inside of the float leading edge is needed, and you also need to rough up the water. The floats are sticking to it. The reason it tipped when it did get off was it wasn't ready to fly. You might pick up some speed by adding just a touch of down elevator to get the back of the float out of the water and get it on the step. Then you can slowly lift it off and don't climb fast till you get speed up.

If the water is glass, it is harder to get it to go because it sticks. You can do a bunch of circles at high speed to rough it up and then go across them to unstick and get it to lift off.

Might also have a little power problem. I had one that did the same thing and just couldn't get off the water. Put a larger engine on it and it took right off.


Good luck. You will have fun when you get it going!



4*60 -> Won't go airborne!!! (7/15/2003 6:49:05 AM)

Isn't the step supposed to be at CG or 1/2 inch behind. This looks possibly ahead of CG which would help keep the rear of loats on the water at speed. Not what you want.



JimCasey -> Won't go airborne!!! (7/15/2003 7:00:30 AM)

I believe the floats are too far forward. My reference tells me the the effective step is the WIDEST point of the step when the floats have a tapered step like the GeeBee floats.

Also, the floats look to be larger than the traditional guideline of 75%-80% of the length from the prop to the rudder hinge. The only thing this really hurts is that the floats are heavier than they should be. Your floats look to be nearly the full fuselage length.

You also need to add some incidence to get the nose up. With the way your floats are mounted, make a 1" long mending plate from aluminum strip and add it to the front float mount. one hole in 1/4" from the end will bolt to the float, and one hole 1/2" higher will bolt to the existing hole in the struts.

SPray deflectors, as described earlier, help.

Initially, start your takeoff with full up elevator. This gets the nose up and helps the prop clear the spray. After a second or 2 the plane will pop up on the step. Relax elevator and let it accelerate. Then gently give it 1/4" back stick and it will lift off.

Personally I continue not to be a fan of GeeBee floats, and suggest that you get a good set of foam floats from one of the vendors listed in the FLFLFL website (below). OR from Plane Fun FLoats who participates in this forum as "seaplane". I keep promising myself I will post his link in the website, but still have not done it.



BillHarris -> Won't go airborne!!! (7/15/2003 6:53:42 PM)

quote:

OR from Plane Fun FLoats who participates in this forum as "seaplane". I keep promising myself I will post his link in the website, but still have not done it.


Isn't that site:

http://www.geocities.com/planefunfloats/

?

--Bill



Captain Solo -> Won't go airborne!!! (7/15/2003 8:35:49 PM)

Yes, my floats are too long, but after the initial investment I'm going to try to make them work. Following you guys' advice I'm going to put a spacer on the front float mounts, move the floats an inch forward, and mount some spray deflectors on the floats.

One question, if I mount the deflectors off the top inside edge of the floats, how far should they stick out over the edge?

Thanks



JohnBuckner -> Won't go airborne!!! (7/15/2003 9:44:21 PM)

Captain I have been following your adventures with the Gee Bee's And I just would like to say that I agree with the other posters about you problems i.e. CG to far aft due to confusion over the less than adaquate 'v' shaped step and probably inadaquate float decaladge.

I only have one pair of Gee Bee's that were given to me that are about 27 inchs long. they have been successfully used on two RC ships and one controlline however on the first RC they did have a lot of sticking problems and I beleive totaly due to the poor step design. The solution on the second RC ship turned out to be carving simple triangle shaped balsa blocks epoxied to the bottom at the step to form a straight straight tranverse step and eliminate the 'v' shape. Also doing this it makes it possible to deepen the step a little so it is not so shallow. This allows for better venting of the after hull and minimise's sticking also. The shaping blocks are easy to make and after glueing to the bottom and sanding just apply a little glass over the wood portion.

Now the effect of installing these blocks will actually move the true step aft and coincide where you thought it was in the first place and your CG will be in the appropriate range. Doing this simple step and increasing the float decaledge a bit with front spacers, I beleve will make your ship quite flyable.

The only other possible problem is the front struts are pretty far aft on the aircraft and this will increase flexability some but that is not why you could not get off the water.

John



4*60 -> Won't go airborne!!! (7/16/2003 1:37:05 AM)

Please ignore.



Captain Solo -> Won't go airborne!!! (7/16/2003 2:29:59 AM)

Here is an updated picture for you guys with a temporary spacer mounted between the fuse and float legs, and the floats moved back an inch.

I'm going to give it a test tonight to see if it performs better and if any additional improvement need to be made.

Next thing is installing the splash deflectors; if I mount them off the top inside edge of the floats, how far should they stick out over the edge?

Thanks!

[img]http://www.tgwebworks.net/webimages/solo_update1_side.jpg[/img]



JohnBuckner -> Won't go airborne!!! (7/16/2003 3:39:26 AM)

Whoa, forgive me Captain but in my opinion that is way to much, now the problem is the wing will be close to a stalled angle of attack when it leaves the water. Best way to use spacers is make a bunch out of 1/8ply and you can stack them to make adjustments. If it were me I would split the diff from that and what you had before.

John



Captain Solo -> Won't go airborne!!! (7/16/2003 4:19:30 AM)

Well, I guess it is pretty aggressive. I'll fart around with it tonight between the shop and the water to see how much to leave on there. Thanks for the great input!



JimCasey -> Won't go airborne!!! (7/16/2003 6:01:36 AM)

The good part about this is how much you are learning. Once they work, you are going to be so pleased.

And don't worry, we ALL did it the same way you have. Bought badly labeled floats, slapped them on the plane with inadequate instructions, and some of us got lucky and they worked somehow. A lot of us went through what you are going through. That's part of why a lot of guys think you need more power. With enough power, you can rip an anvil out of the water.



Captain Solo -> Won't go airborne!!! (7/16/2003 9:03:47 AM)

Well, I got farely fed up with it tonight and took the floats off and put the wheels back on. I'm thinking of just building up an entirely different plane with some nice floats you guys have recommended. With 26 acres of water in the front yard I doubt I'll have a hard time finding a use for a dedicated float plane. I've been looking at the GB Piper Cub. What other easy kits would you guys recommend? I really don't like sea planes.

I'm going to try different floats on the Solo in the future sometime. I just need to wait awhile till I forget about the $45 lost on the GeeBee's.

Thanks!



Wayne22 -> Won't go airborne!!! (7/16/2003 9:36:46 AM)

Any trainer will make a terrific float plane - it is just a matter of getting it set up properly.

Your current setup will fly if you make a few adjustments as mentioned above..... sometimes it takes patience and persistence....



4*60 -> Won't go airborne!!! (7/16/2003 10:36:32 AM)

I agree. I don't think you should write off the geebee's yet. That angle relative to the floats was pretty severe in your last picture. Try the same position but less spacer(almost level with top of floats. Use up elevator during inital run and then ease off and it'll get up on plane and then should be able to take off. What you have will work.



JimCasey -> Won't go airborne!!! (7/16/2003 3:56:07 PM)

Look at it this way: You ain't gonna hurt the geebees. Fiddle around with them. Have fun. THen when you get some "real" floats, they'll be installed properly and the plane will fly "right out of the box".

You are 99% there. Take out half of that spacer and you will have a flyer.



Captain Solo -> Won't go airborne!!! (7/16/2003 7:15:03 PM)

Ok, I'll work on taking half of it off later today and see if it makes a difference. I was getting zero lift with it the way it was. You guys have been a load of help, without having this place for some guidance I'd be lost! Thanks



JimCasey -> Won't go airborne!!! (7/17/2003 5:22:44 PM)

here's a Full-size cub. Looks like 4-5 degrees positive.



jrf -> Full scale (7/17/2003 9:20:27 PM)

Now come on guys. Do you really think the proper setup on a fullscale floatplane has anything to do with the proper setup for a model floatplane? Our power-to-weight ratios and wing loading are orders of magnitude different. Our airfoils are unique because the Reynolds number has a few less digits in it. Do you try to fly at scale speeds? (17 MPH for a 1/4 scale Cub)

There are several workable ways to set up a model floatplane, but emulating the full scales is almost guaranteed to be wrong.

Jim



JimCasey -> Re: Full scale (7/17/2003 10:00:04 PM)

[QUOTE]Originally posted by jrf
Do you really think the proper setup on a fullscale floatplane has anything to do with the proper setup for a model floatplane?

[COLOR=red]Yes. Angles of incidence (decalage) & balance points, are essentially similar. The big end of the floats goes in front, and the floats go on the bottom.[/COLOR]

Our power-to-weight ratios and wing loading are orders of magnitude different.

[COLOR=red]Hmmm. 65hp cub, with "generous estimated" gross weight of 1000 pounds. rounds off to 1 hp/15#. (Somebody will undoubtedly correct me with an official rated gross weigh for a J-3 cub).
A scale cub weighing 15# with a 1.6 hp .90 would have a p/w ratio of 1 hp/9# [/COLOR]

[COLOR=red]So the model power-to-weight ratio is better, but not "Orders of magnitude". (An "order of magnitude" would be 10 times as much)[/COLOR]


Our airfoils are unique because the Reynolds number has a few less digits in it.
[COLOR=red]Yep, model airfoils are less efficient because of scale effect. that's a lot of why they fly with a greater power/weight ratio. [/COLOR]
Do you try to fly at scale speeds? (17 MPH for a 1/4 scale Cub)
[COLOR=red]You mean you DON'T???[/COLOR]

There are several workable ways to set up a model floatplane, but emulating the full scales is almost guaranteed to be wrong.

[COLOR=red]I apologize that I am still missing your point. The setup of the Cub shown would be well within any set of model setup parameters I have ever seen. Certainly I never advocated scale wing-loading, but the setup geometry is similar. Here's a GlaStar as another example[/COLOR]



Timbersnake -> GeeBees (7/17/2003 11:06:32 PM)

In our little club, we only fly float equipped airplanes. Nothing else. The predominant float choice is the Great Planes built up float. They are super strong and 'crash resistant'.

Geebees are, well, a bad float design. The only good thing about a Geebee float is that they make you look like a pro when you come in to land because they STICK to the water. You touch, and BAM, you are stuck. This feature also makes it incredibly difficult to take-off. Even with perfect setups (AoA of wing re: floats, center of gravity, step placement) these floats stick to the water so well that taking off is hard for a seasoned pilot, and nearly impossible for a rookie. What invariably ends of happening is the plane finally gets moving fast enough create the lift required to break the suction of the floats, and the pilot has almost full up elevator applied to keep on step...when the plane breaks the water it goes straight up, stalls, drops a wing, and plunges back in.

Now, the GP float sizes are a little off (in our general opinion). The GP 20 sizeds floats will generally fly a 40 sized aircraft, the 40's will generally fly a 60-90 sized aircraft, and the GP60's will fly 1/4 scale. I have a set of GP60s on my Ultrastick 120 w/OS1.6fx. Lots of free board left!

For better water handling, we will typically place the float step (this should apply to floats other than GP as well) a smidge (1/4 - 1/2 ") AHEAD of the aircraft CG. This placement makes it easier to get the tail down and the floats on step. Once on step, hold gentle up elevator to keep the front portions of the floats out of the water. If your airplane is 'ground looping' on the water while it is on step this is likely what is wrong. Be sure to hold a little up, and if that doesn't take care of it, move your step a little ahead of the CG.

This isn't rocket science, these things will fly without the help of NASA engineers. A plane that wont taxi and has bad water handling habits is no fun.

p.s. I have lately started removing the water rudders from my floats. When I build a new airplane I do not include them. I have found that the newer aircraft have such monstrous air rudders, that a water rudder is not needed. Removing these systems saves weight and the planes actually look a little better too! (uncluttered) Sure, if you are building a scale Cub, you'll need rudders, but any of todays fun flys shouldn't need one.

I have attached a picture of a buddie's Stinger 120 with GP 60 sized floats (they are huge) on its take off run. Check it out!



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