• Edo Floats Maintenance Manual Transmission
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Installation and Continued Airworthiness manual-Aerocet 3400 Floats on. Edo Floats Manual Transfer. CLAMARFLOATS Operator’s Manual. We have drawings in. Again known as the “Edo Rule”. Place your floats on a round PVC pipe and find their C of G. Edo Amphibious Floats Booklet (877) 318-1555 Account My Account; My Orders; My Wishlist. The majority (if not all) of these photos are of BuNo 0268, the first production Devastator, and were taken throughout 1937 at the Douglas factory in Santa Monica (judging by the background). This aircraft was subsequently retained for testing by the Navy, later being fitted with Edo floats as the TBD-1A. Well this is a lively site. In case someone else wanders through wondering about 2705 floats on an early 180 2705s are not on the 180 TC. Edo has two STCs. See Service Bulletin No. 18, Airplane Flight Manual Supplement (AFMS) No. Floatplane: Fleet 2500, EDO 248A2440 or 248B2440 Floats: 2300 lbs.

Floats

Corrugated Skin Repair

Replacement of a Panel

Outside the Member

Inside the Member

Edges of the Panel

Repair of Lightening Holes

Repairs to a Pressurized Area

1. Remove the damaged skin section.
2. Radius all corners to 0.5-inch.
3. Fabricate a doubler of the same type of material as, but of one size greater thickness than, the skin. The size of the doubler depends on the number of rows, edge distance, and rivets spacing.
4. Fabricate an insert of the same material and same thickness as the damaged skin. The skin to insert clearance is typically 0.015-inch to 0.035-inch.
5. Drill the holes through the doubler, insertion, and original skin.
6. Spread a thin layer of sealant on the doubler and secure the doubler to the skin with Clecos.
7. Use the same type of fastener as in the surrounding area, and install the doubler to the skin and the insertion to the doubler. Dip all fasteners in the sealant before installation.

Stringer Repair

Former or Bulkhead Repair

1. Stop drill the crack ends with a No. 40 size drill.
2. Fabricate a doubler of the same material but one size thicker than the part being repaired. The doubler should be of a size large enough to accommodate 1⁄8-inch rivet holes spaced one inch apart, with a minimum edge distance of 0.30-inch and 0.50-inch spacing between staggered rows. [Figure 12]
3. Attach the doubler to the part with clamps and drill holes.
4. Install rivets.

Geometry of Float Rigging

2014/06/28

CG method update 2014/06/09

(Homebuilt 170/180hp on Edo 2425 for sale!)

This information isrelevant and accurate for light wing loading and low stall speed aircraft such asthe 1200lb gross Rans S6 and 7, however, the same considerations were used inrigging the homebuilt 170 on 2425 Edo’s shown above.

To position a set of floatson an airframe we need to decide on four measurements:

1.The distance between thefloats;

2.The height of the airframeabove the floats

3.The angle between thecenterline of the airframe and the bottom of the float.

4.The fore/aft position ofthe airframe on the floats and with Lotus floats, where to positionthe spreader bars/tubes;

SeeNew Rule

First, Centre to Centre width.

If you look at successfulfloat installations it is reasonable to conclude that the first two are basedon personal preference and what look the builder wants. There is a range offloat center to center distance of from 40 to 50% of float length. My Murphy1500 floats (174”) came with a width of 48%; I cut them back to 80” or 46%.

Many 1260 Full Lotus aremounted at 72” which is 44%; My 1350 LAS floats came with a width of41% but I’velengthened the spreaders to 77” or 46%.

A wide stance will improvecross wind stability but will make standing near the side of a tandem fuselagemore difficult.

This S6 on Czech amphibs hasa 75” width (and 20” height). Because it is a side by side plane with a widerfuselage the owner feels the struts look too vertical but it still works justfine. Also the attachment points to the floats are on the spreader bars so thatfurther narrows the apparent stance of the struts.

The 1450 Lotus floatsdescribed further down in this write up have a different looking geometry and acentre to centre distance of only 66” or 40% of the length on this Rans S7.

Whereas these 1260 are 73” centre to centre:

One final pointabout width between the floats is related to the size of the dolly you mightwant to use to pull the plane out of the water. Narrower measurements mighteliminate some of the rigs out there that are being used on certifiedaircraft.The trailer shown above needsabout 46” and that would mean it would not handle the 1450’s above with 66” CC.

Height of fuselage above floats.

This measurement also seemsto be highly related to personal preference. Yes, you need to keep the propaway from the water but most installations result in the prop tip being muchfurther off the water than the minimum 12”,

My first Rans S7 was mountedat about 16” above the floats like this and it swung a 72” prop:

It flew well (except for sometypical Lotus porpoising) and was very easy to get into without the need for astep on the struts but certainly lacks “dock appeal”.

One of the highest mountingsis on Murphy Rebels where the company rigging shows 31.5” for the fuselageabove the floats. One experienced Murphy guy uses 29”.

This Rans S7 on Czech amphibsis at 20”

So, with all this in mind, Iwent with 80” width and 24” height on these Murphy 1500 on my Rans S7:

There is also somecorrelation between height above the floats and step position when you adoptone approach to positioning the step which will be discussed later.

Angle between datum and floats.

An interneter from Australia (Jim Williams) who has a beautiful L19 on amphibs waskind enough to send along an article by J Frey, a long term Edoguy, and an Edo drawing of his floats. I subsequently contacted Mr.Frey who put me in touch with a former engineer from Edo, Leon Kaplan, who provided much more information.You can see his article, unfortunately minusthe drawings at:J Frey

Frey points out that for besttake off performance we want the wing at the angle of attack for maximum liftwhile the floats are riding in the water at an angle for minimum drag. Hesuggests that a flapped wing needs 14 degrees (this is not true for allairfoils but close) so the geometry has to provide this.So, how do we achieve that 14* angle ofattack?

First we need to use thehorizontal datum line of the aircraft as the reference line for rigging thefloats. Next, most designers have built in a positive angle of incidence of thewing center line to the datum line of 2 to 3 degrees. Let’s use three for now.

Frey points out that earlystudies showed floats need to ride at 8 degrees for minimum resistance whileplaning.Thus, if we mounted the floatsparallel to the datum line we would have an angle of attack of 8 + 3 or 11degrees when the aircraft is on the step. So, we need to mount the floats at 3degrees negative to the datum line to get our 14 degrees.

A knowledgeable frienddetermined from studies of similar airfoils that my Rans S7 actually achievesmax lift at 18 degrees. This would require not 3 degrees between float anddatum but 7. I have mounted the floats a little more than 3 degrees andtakeoff, cruise and landing performance is excellent; the best performance I’vehad over four different S7 float planes.

I would predict that cruisespeed and landing characteristics would suffer with more anglebetween float and datum. The compromise here is that we don’t want the nose ofthe floats too low while in level flight to increase drag or to make itdifficult to achieve a slight nose up position of the floats on landing.While I will experiment with this in thefuture, for now, 6 degrees between float and wing CL works well.

When I wasinstalling 2425 Edo’s on the 170 homebuilt shown in the photo at the top,a seasoned FBO operator, Jim Leggat, told me to put 6 degrees between wingcenter line and top of float. Thatworked just fine. So given that the 170 is double the gross of the Rans, itlooks like this is a pretty solid rule of thumb.

Finally, where to position the airframe on the floats(Usually looked at as the fore/aft location of the step)?

June 2014 update:New Rules

After many years and severalunique installations I now propose a major change in conventional thinking.

What I now believe is that weshould just forget about the step, ignore it, don’t even consider where it endsup because where it actually is is of little consequence and we do not need toconsider it in locating the relative position of the floats on the airframe.

Read the above heading againbut now change it to “Where to position the floats on the airframe”.

So, how do we do that? Theanswer is quite simple:

Positionthe floats such that the weight of the floats does not change (significantly)the empty CG of the plane when on wheels

In other words determine thelocation of the CG of the complete float and rigging package when off the planethen mount that CG in such a position that with the wheels removed and the floatsadded, the resulting CG is about the same. You will dothis with a couple of trys using your weight and balance spreadsheet.

Only two issues areimportant: 1- Maintaining the appropriate CG of the airplane and 2- Loading theweight of the airframe onto the float near the Center of Buoyancy of the floats. The problem is we won’t likely knowwhere the C of B is but we can figure out theC of G and it is going to be prettyclose to the C of B.

If you still aren’t convincedthink about this:

Does the step position affectflight characteristics? NO

Do all fast boats have astep? No

Does CG affect flight? Duh

Does loading a boat too far forwardor aft affect getting up on plane? YES

QED

If you do go ahead and readsome of the theory below and think about the opposite concept of loading weight(the airplane) on the float ( how EDO did it), and assume that the C of G ofthe float is near the C of Buoyancy of the float, then this method meets thatrequirement as well.If you disagree,please tell me why this method won’t work.

Back to traditional thinking:

If you ask the average AMEwho has had experience installing certified floats where to position floats ona homebuilt, he likely won’t have much info for you. His experience hastypically been to get a set of rigging made by the float manufacturer for onespecific airframe and bolt it together. He has not needed to know much aboutthe geometry.

Usually,if the aircraft type has been mounted on floats in the past you can find outwhat worked and copy it. But suppose we cannot find such information, then howwould we proceed?Also, how do we knowif what someone else has done results in the optimal configuration?

Onewell known float guy in the Rans world puts the step at 51” aft of thefirewall. For that aircraft, the CG range is 46 to 50.25. Why does this work?Is it the optimal position?

Basedon what Edo (one of the major float manufacturers in recenthistory) shows on their drawings one could argue that where the plane ispositioned relates more to the fluid dynamics of the system rather thanaerodynamics. Edo does it this way: the weight of the bare airframe(without wheel gear) is positioned vertically above the Centre of Buoyancy (C of B) of the float when the float is restingin the water.(And Noel L in NFLD),you are the only other person I’ve come across that also considered the C ofB.)

While most float mountinginstructions have the airframe positioned with the centre line level (anin-flight attitude) and the floats angled down, the Edodrawing brings out the concept of loading the floats as they sit in the waterand positioning the weight so as to keep the floats more or less at the samenose up angle. I like this approach but it requires data that is not easy toobtain.

The discussion of anglesabove deals with the transition to flight, in cruise and landing attitude, noneof which has much bearing on the position of the step. The loading of thefloats by setting an airplane on them could be compared to loading a boat. Thesmall outboard sitting at the dock rests at a specific, more or less level,probably a bit nose up, attitude. If we are loading several people into theboat, we position them not all at the front or all at the back but more or lessevenly distributed to retain that level attitude. I suggest we are loading theboat by distributing the weight equally around the C of B.

Edo Floats Maintenance Manual Transmission

Most floats sit in the waterwith some nose high attitude Frey says maybe 3 degrees (although the two setsI’ve installed are at 4.5* to water).

You need to make a drawing tosee the impact of this:

This drawing illustratesseveral points.

The weight of the bareairframe is positioned above the C of B of the float as it sits in the water. Thekeel of the float is inclined about 3 degrees from level and the aircraftcentre line is inclined at 3 degrees to the float so the aircraft centre lineis inclined at 6 degrees to the water. It is also true that there is a 6 degreeangle between a line perpendicular to the fuselage centre line and the linedrawn through the C of B.

The distance that the bare,empty CG is ahead of the step is the sum ofa + b + c.“c” is how far the Cof G of the floats is ahead of the step and we can determine that. On my Murphy1500 that distance is 4.5”.

Based on knowledge of the ratios of surfacearea to volume, I would bet that the C of B is significantly ahead of the C ofG (this is length “b”). Suppose we estimate that the Cof B is another 4” aheadof the C of G.

We can calculate the lengthof line “a” by estimating the distance the aircraft CG is vertically from the float C of B. With the estimates from thedrawing, you can see that the distance “a” is 5.2”

That puts the step 4.5 +4 +5.2 =13.7” aft of the bare CG which forone S7 was 44.7” giving a step location of 44.7+ 13.7 = 58.4”. So even if myestimate for the distance that the C of B is ahead of the C of G is way off andwe reduced it to zero, we still have 54.4” for step position in this example.

So, what do we use: 51”, 54”or 58”???Especially with a tandemseating aircraft you may have to decide what loading you want to rig for. Inthe case of the 54” choice, with full tanks and just the pilot the plane willclimb up on the step, level off and fly off the water with the stick neutral.With a 200lb passenger, considerable forward stick is needed to get the planeover on the step. If this aft loading were most typical for me I might bebetter to go even more than the 54” but since I’m more often alone I’ll leaveit at 54.

Frequently in discussions offloat positioning, when CG is referenced, it is not clear which CG is beingused. Somerigging instructions for thelevel attitude method use the most aft CG limit; usually which CG being used isnot defined. You have to keep in mind what CG is being discussed.

The CG Method

This is a totally differentview of the problem which only looks at weight of the floats on the airframe.

One important point here isthat you should always weigh the floatswhen they are rigged and calculate their CGto use in the work up of the new aircraft CG after adding thefloats.Knowing the float CG lets uschoose this other method for obtaining the fore/aft position. Why not forgetabout where the step goes and hang the floats on with the float CG right at theaircraft empty cg on wheels? This way we are not changing the empty CG when onfloats andwhat we are used to inloading the aircraft still applies when we go to floats.Let the step then sit wherever it ends up asa result of the float design

This is the approach the PGfloat manufacturer uses and it works. With PG 1400 floats their CG is about 12”ahead of the step. The Rans S7 I’m mounting them on has an empty Cg of about73/46” (aft of prop hub/aft of firewall). This will put the step quite far aftat 85/58” from the datum.(compared tothat popular 51”!)

If you are interested in somecomments on Pierre Girard and his floats see:pgfloat

Earlier I mentioned that thehorizontal distance of the step from the cg is related to how high the plane isabove the floats.

Visually slide the floatscloser to the plane in the above diagram. As you do that, length “a” getssmaller which means that the sum of a, b and c is less, thus the step movesforward along a line parallel to theaircraft centre line relative to the CG. If you lower the floats andthus increase the distance to the C of G of the plane, the step moves furtherback from the CG.This means that it isnot enough to say where the step is horizontally without also giving the heightof the aircraft above the floats. Or looking at it another way, that S7pictured above with the fuselage only 16” above the floats will handledifferently from the one with the fuselage 24” above the floats with the stepat the same distance from the CG.

After posting this site tothe Matronics Seaplane list, Hagen Heckel from Germany pointed out that German regs REQUIRE the step to be100 mm or 4” aft of the most aft CG. While this doesn’t take into account theeffect of height of airframe above the floats, it appears to be in line withthe Edo method and provides a workable rule of thumb formounting floats.

In reality, the precise stepposition is not critical. For example, on the Rans S-7S, the aft CG limit is50.25”. One float guy in Minnesotaputs the step at 51” and his installations do work. One noticeable differencein the feel of the S7 with floats mounted there, is that there is very little,if any, nose over tendency on a level landing, whereas any Edoinstallation I’ve flown has required that you be ready with back stick on alevel touchdown to counteract the nose over tendency. Also, at 51”,considerable forward stick is required to get the plane on the step when loadedtowards aft CG limit. This result does make sense knowing that, at 51” theweight of the airframe is at least 3” further back than what the Edomethod would require.

It is likely that for a fullyload aircraft the more forward fuselage position called out by Edo (andGermany) will allow a faster climb up onto the step than would be the case withthe weight further back (the boat analogy illustrates this too). With lightlyloaded aircraft this would be less noticeable.

With this in mind, I movedthe step on the 1350 floats to 5” aft of CG. This also seems to work fine. Witha 220lb person in the back seat, the heal of the float submerges slightly whenI also stand on the float beside the rear seat, so I am going to move thefuselage another inch forward.Why notif fluid dynamics is the only issue? Yes overall CG is still fine.

These floats have a unique Mshaped bottom forward of step. They appear to accelerate more quickly as theyget on the step but ride noticeably harder on waves than a straight V bottom.

Lotus floats have less of arise from the step aft so the S-7S below is mounted at 4.5 degrees to the floattop so that little rotation is required at lift off. The wide angle isnoticeable but they are still faster in cruise than a set of Murphy 1500’s thatwere on the plane previously.

The step is also further aftto provide more rearward flotation when loading because these floats tend tohave minimal rear end flotation.

Some thoughts onLotus Floats

First, I should point outthat, overall, I have been a proponent of Full Lotus floats for years eversince I bought my first Rans S7 on 1260’s in 2003. In fact, the company hasused my testimonial on their site:

(Full Lotus floats areterrific. They can take a lot of abuse from rocks or shallow water and handlereally well.)

and Aircraft Spruce has apicture of one of my ex planes on their Full Lotus page.

However, after the 1450floats came out I did have some reservations due to their unique proportionsand found the company somewhat reluctant to provide technical info.

General comments:

These “air bag” floatsperform quite well and have advantages over other materials which include:

Less easily damaged when beaching,

Provide some shock absorbing on a hard landing,

Quite useable in the winter and more maneuverable thanskiis,

A puncture may be easily repaired temporarily and willaffect only one bladder of the 8,

Edo Floats Maintenance Manual Pdf

No pump out required.

The disadvantages are thatthey do take on a small amount of water inside the bladders which have to bedrained at least annually and the air pressure must be monitored frequently dueto temperature changes. While they tend to be inexpensive, they do have alimited life. Also, they do not provide as solid a surface for standing on asother designs.

Here is a link to a video ondraining the floats:http://www.youtube.com/user/kitfoxflyer

For more thoughts on the pro’s and more con’sof these floats see Dave Loveman’s site:

http://www.ultralightnews.com/lotus1/lotus.html

While Dave makes some goodpoints, I would disagree with a couple of things he says. For example he feelsthat: “1260 floats do not have enoughfloatation in the front section of the float for most two place, tractoraircraft.”.It is not reasonable to make this blanket statementwithout specifying the gross weight of the aircraft.From my experience aircraft like the earlyRans S7 at 1200lbs gross and 625 to 675 lbs empty, work fine on the 1260floats.

Dave also suggests that theconfiguration of the aircraft and the position of the significant weights suchas engine, pilot and passenger have a bearing on float performance. He says:

“In most pusher configurationaircraft the weight put on the craft is distributed over the full length of thefloat.”And: “On a tractor aircraft thefull weight of the engine sits on the front section, with two pilots and fullfuel normally located near or on the middle area of the float.”

My understanding of thephysics of this is that the only crucial issue is where the C of G of theaircraft is positioned on the floats. The floats only see this CG weight andthey “know” nothing about how it is distributed in the airframe. Thrust linescould make a difference but not whether or not the engine is up front.

Position ofspreader bars/tubes.

Most rigid floats have thespreader bars positioned more or less equally ahead and behind the step.

This also seems to work finewith Lotus floats but occasionally you see variations. These 1260 floats havethe spreaders much further forward, perhaps to suit the location of hard pointson the airframe but this setup does result in some additional flexing of thestiffener tubes. Perhaps a third, partial stiffener should be added.

The 1450 installation belowalso has the spreaders further forward but they do come with pockets for the thirdstiffener and the tail section is shorter than the forward section (and shorterthan the aft section of 1260’s) so has inherently more stiffness than with the1260’s above.

Here are 1260’s with a 3^rd stiffener:

Why focus on the1450?

Until recently there werethree sizes of Lotus floats in the light aircraft range: 1220, 1260 and 1650.Clearly there was a large gap between the 1260 and 1650. The 1260 are asatisfactory size for 1200lb gross weight aircraft like the earlier Rans S7 butas mentioned above, the 1260 floats could use a little more flotation in theheels and are a little small for 1300lb gross aircraft.Now that it is common to see the S7S at 750lbs empty, the 1260 is a marginal choice yet I suspect many people would feel thatthe 1650 was too big a float (although it may not be).

The 1450 model fills thatgap. But it turns out that the 1450 is not an enlarged 1260 with proportionateincrease in all dimensions. The company was quite creative and expedient in theway they came up with this higher displacement float with an unorthodox shapeand as a result have generated some questions which they were more or lessunwilling to acknowledge let alone discuss informative answers.

To create the 1450 they usedthe longer front end from a 1650 mated to the shorter heel of a 1220. In other words, compared to the1260, we have a bigger front end with a SMALLER rear end with the result thatthe step is far aft of the mid point of the float.

Apparently thecross sectional area of the 1260, 1450 and 1650 forward tube is the same; justthe lengths vary.

Here is a chartshowing the dimensions of the floats taken from earlier measurements on thecompany web site where the 1450 numbers are derived from the 1220 and 1650diagrams:(currently the specs onthe Lotus site are slightly different)

You can see from the abovethat the cross sectional area of all of the forward sections of these floats isapproximately the same so overall bulk does not change just the lengths.

I’ve cut out some scale side views of thesefloats based on the above dimensions to illustrate the differences between thefloats (top -1450, bottom - 1260):

These cutouts show how theadded length at the front contributes significantly to the increased flotation(1260 to 1450 = 190lbs) but also that the heal of the float aft of the step ismuch smaller (a rough calculation yields maybe 50 lbs but based on Lotusnumbers it is closer to 35).

This superimposed view showsthe heel volume difference with the 1450 having the smaller volume:

The patterns taper to asharper point than the actual dimensions would suggest because there is also anarrowing of the float from side to side and the objective is to represent thecomparative volume. Since the actual measurements mentioned above show aslightly thicker and wider tail end on the 1450’s, the pattern above should bejust a little larger at the tail end. The length difference, however, iscorrect so that the decreased aft volume does still exist.

What this means is that if1450 floats are replacing 1260’s and if they are mounted with the step at thesame position (since most people use the step as the significant referencepoint) then there will be LESS flotation at the aft end even with these largerfloats. Clearly, mounted this way, they will make the aft flotation issue worse.When asked about mounting these floats (as I did a couple of years ago) thecompany’s response was: “they are mounted the same as the 1260” yet clearlythis will result in too little aft flotation and doing so would seem tocontradict the significance of the C of B as discussed above.

On most floats the step is positionedat close to the mid length point of the floats with the Centre of Buoyancytypically a few inches ahead of the step (like it is on the 1260). Earlier Imentioned the importance of the C of B in rigging the floats.While we tend to use the step as a referencepoint, it is really the C of B position relative to the aircraft CG that iscritical (based on the material from Edo Corporation, see details earlier inthis page).

Now suppose we line thefloats up along a line joining the estimated C of B of the floats:

By using the C of B as theprimary guide rather than the step, the problem of the reduced heal flotationwould be addressed automatically but we would need to have the step at least12” further aft and the question is would this affect rotation and lift off?

Clearly then, these floatshave different proportions to other Lotus floats and to floats from othermanufacturers so one would expect the manufacturer to provide some additionalguidance for rigging them on an airframe. The initial response from thecompany, however, was that they should be mounted just like their other floatswith the step between 0 and 6” aft of the aircraft Cg.Given the smaller aft volume this can simplynot be the case. They must be moved further aft by some amount to compensatefor the reduced aft volume and prevent modest aft loads from sinking the floatand to take advantage of that more forward C of B for aft loaded aircraft.

One other possible issue isthat if the floats are mounted with the step in the same position as it was on1260’s, the C of G of the float will be further forward and may complicateweight and balance issues as well. With the early S7, the aircraft tends tohave a forward CG and mounting floats whose cg is more forward could be a concern.

I wanted to talk to peoplewho have actually installed and flown this float after using a 1260 to see howthey have dealt with the aft flotation issue and the step position. The ownerof Full Lotus, Jeff Holomis, refused to provide such references nor would hecomment on any research they have done on this issue except to point to someYouTube videos which show airplanes taking off and landing.I suspect they may not have even thoughtabout it and certainly not done any real, substantial testing. All Jeff wouldsay is that there are many happy customers.

In 2009 I discovered that KenSmith had installed a set of 1450’s on a Rans S7 but it had not yet flown. Hesaid he moved the step back maybe 5” although this later proved to be not thecase. He did say a set is working OK on an S6.

Later that year Iwas able to take measurements and fly the 1450 installation that Ken Smith madeup (a Rans S7 long tail with a 100hp Rotax). Frankly I was pleasantlysurprised.

Turns out Ken hadnot actually moved the floats further back but used his 51” step position as hedoes for most of his installations which makes it easy to evaluate the companysuggestion of not changing the rigging from what 1260’s used. Here is a pictureof Ken’s setup:

The first test wasto put a person in the rear seat and stand on the float beside him. Asexpected, the heels of the floats submerged illustrating that there was notenough aft flotation.

While overalltake-off and landing characteristics were quite good, the owner did feel thatthe fuselage should go further forward which should improve the climb up ontothe step. My feeling is that the fuselage should move forward at least 6” sothat the step is at57” aft of thefirewall and 6” aft of the most rearward CG of 51”.On the other hand, the overall performancewhere it is, is quite acceptable with one or two people onboard. If you look atthe videos you will see that the flotation is noticeably better than the 1260’swithout the look of much bulkier floats (as you would expect since the forwardbarrel size is the same cross section).

Edo Floats Maintenance Manual Diagram

You can see somevideo of this aircraft on my picturespage.

/blaupunkt-radio-code-free-download.html. Ken’s rigging looksquite professionally made and his choice of square tube spreaders with someadded streamlining works very well. Ken puts his spreaders closer (45”) thanmost people do (55” to 63”) and he mounts the rear spreader closer to the stepthan most people do (usually the step is about ½ way between the spreaders).

2008 Rans S7 Long Tail built by Brian Sandercock in Kenora Ontario

With the fuselage6” further forward, the forward rake of the struts would not be so pronounced(if the shift were done via the rigging and not just by sliding the floats onthe existing rigging). Ken also has used a narrower float width than I prefer;his are at 66” whereas 72 to 75 is more typical.All of his rigging was well done includingthe water rudder set up and stainless fitting in the floor for the rudder pullup cable.

Finally, here isone comment on the choice of angle between the floats and the fuselage wherethe typical measurement is 3 degrees. I went to over 4 on the S7S above whilethis set of 1450’s is at less than 2 degrees and they fly off and land justfine. My conclusion is that trying for 3 is still a good approach but a littledeviation won’t likely hurt at all.

Update 2009/06/19

Just heard thatthe owner has moved the floats aft 6”.He reports that handling is much better; climb up onto the step hasimproved and flat touch downs require some (normal) back stick rather thanforward stick which is common with Lotus floats to stop proposing. There-positioning was accomplished by sliding the floats back under the existingrigging. This will put the rear spreader almost right at the step. On 1260’sthis would result in considerable flex of the aft portion of the float butperhaps the third stiffener tube and shorter tail section on the 1450’scounteracts the flex.

So, myconclusions are that the 1450 is quite an acceptable choice (and much betterthan 1260’s for the heavier S7S) but should be mounted at least 6” aft of1260’s or other floats with a more typical step position.

Here is anotherfull shot of Brian’s very pretty S7:

Click for:More info onfloat sizing

Spent some time looking atthe setup of this pretty Baby Ace on Zenair floats.

During a recent rebuild, theowner made several rigging changes to both floats and airframe. The floats arenow sitting at only 4* between float and wing centreline and the step is a full6” aft of the aft cg. With these variations it will be interesting to see howit performs (although it seems to be more in line with the German thinking).

Info on rigging design.Spreadsheet for predictingtake-off time.

Back to Float topics page

C/G anomalies on the Rans S7.

The S7 fuselage waslengthened in 2001 and called the S7S. There is no change in the airfoil or forwardgeometry. As mentioned above, the CG range for the early models was 74 to 81”aft of the prop hub.

For the S model, Rans changedthe datum line for CG calcs to be the firewall. The range for the S model is 46to 50.25”aft of the firewall. For sometime I assumed that both aircraft had roughly the same CG range and aft limitbut a close look at the numbers shows this is far from true.

First Rans has narrowed therange from 7” on the short tails to only 4 ¼ on the long tail. Next bysubtracting the 26” distance from hub to firewall, the converted range on theshort tail is 48 to 54”. The S model has had some FAA involvement.

I’m no engineer but maybe itmakes sense that if we have increased elevator authority due to the longer tailwe could tolerate the more forward 46” cg.But why does the later model have a restricted rear CG position byalmost 4”? Should short tail owners learn something from this???