GJ3uilding the 'l0MSEY CHAPTER V

The I{amlcy "Flying Bathtub" I, the editor', an,wet' to the In, I,tent demand. for • tWOo-place alde-by_. lde ,port plane that I, euy to fty and th.t can be re lied upon fOf' ("ro .. _country wlH'k. Thl, little ,hip I, powered ..... ith the rugged and reliable Aeroncs motor which develop. thirty honepowcr and which give. you • cruiling ran,"!: of ISO mile. with only five ,allona of ..... ollne II, your tank .

THE Ramsey "Flying Bathtub" is a light-ly powered ship which has ht!en designed

with the sensible intention of creating a modcratdy fast trainer which can also ~ used for cross-country work where t he own­er's pleasure rather than spt!ed is the primary consideration. Inexpensive to build. simple in its general design and structural details. it has certain definite characteristics which will appeal to one who appreciates real per· formance. .

Perhaps the outstanding single character­i$tic of the "Bathtub" is the way it handles in the air. Test flown by one of the best­known Northwest pilots. it proved [0 be US)'

to take off. simple to handle in the ai r, and a positive joy to land. Veteran pilots who have since flown this job agree that in spite of its moderate horsepower and general light weight. the bathtub behaves and flies exactly like a large and powerful ship.

This is of the utmost significance to ama-

teurs. who are apt to find in the average light plane a tricky behaviour which calls for more experience than they are likely to have. The pilot who test flew this job has remarked that it is safe and easy to fly; that it will land itself. and that it has no apparmt vices.

Even a beginner can pull the " lhthtub" off the ground with a run of I 00 feet or less. ( lly beginner I mean a student pilot and NOT any penon with no training at all.) Once in the air. its extreme ease of handling. remarkable stability and responsiveness to controls make it an ideal ship for sport pur­poses. With the unusually low landing speed of twenty miles an hour. many of the difficulties presented by this operation arr automatically eliminated. The nature of the design permits ex~ptional vision. and while this feature is important at any time. it hf... comes paramount in landing.

The " Flying Bathtub" is definitely not in thr "Flyin(:" Post Card" class. but with the

Flyii

Flying 13athtub by W.H.

RAMSEY De.igner

case, and th~ simple littl~ motor is not only extremely accessibl~. but also suffi· ciently rugged to stand lots of work without constant attention.

Fuselage and Outrigger The fuselage. tail sur·

faces and land in!: gear are built of chrome· molybde­num seamless steel tubing of co nventional braced type. 'Ine wing is of wood and fabric con s truction. All plate type fitti ngs are mad!' from .049 chrome· molybdenum stetl. and on!}' aircraft steel bolts are ad­visllb le.

In starting to build the fuselage it is necessaf)' to procure a Rat surface, pref­erablr a table, large enough to layout all the measure­m~nts. All measurements. un less otherwise specified. are from center to center of the tubing. Car~ should be taken to have these abso­lutely accurate.

l'h .. " ., ...... ., ...... t ...... nn "f."d 1 .. 1 .. or .. -.... II. wlth" .. 1 .,.,n"lnnl .U .. ,I_ After laying out the out· line from the centeno make allowanc~ for on~-ha1f the

II ... ,. bul ,,, ... ""n' ...... II,' .e ........ U., .. _O .. IOU"III: .. ,.k .. " .. " .... tlo .... "I ........... .

Aeronca motor may two said to have the per· formance and other qualities usuallr found in larger ships. Although its performance is best when used as a sillgle--seater. it carries a pasS('nger with little loss in eflicienc\·. Its low weight makes it possible for one person to move it into and out of the hangar with

tube's diameter, and drive, straight in, ten-penny nails Ix:tween which the tubing will Ix: placed and held true until 5J)Otled together with a welding torch.

Care must be talcen in welding chrome­mol}bdalum tubing, as insufficent heat will make a very nice-looking weld. but upon de· stroying the weld. it will be found that th~

Specifications of the Ramaey "Flying Oathtub" High Speed ....... . ................ ...................... . .. 65 to 70 m.p.h. Cruiling Speed ................ ........... ......... 60 to 65 m.p.h. Landing Speed ................. ....... . .................. . 20 to 25 m.p.h. Initial Climb (I pe ... on} ...... .................... ............... 00 ft. per minute Initial Climb (2 person.) ...... ........ . ................ 300 ft. per minute O •• oline C.padty . .... ................................ 5 gallons Oasoline COn.umptlon ...... .......... ........... 2 Xall. an hour.t Crulling Speed Motor, Aeronca, 2-eyl. horitontaJ opposed air cooled ....... JO h.p. at 2500 r.p.m, Span ..... . ...... . . . ..... . .. . ............... J2 ft. Chord ........................................ _ .......................... 5 ft. J In. Wing Area .............................................................. 168 Iq. fL Weight (with gu and oil) ... ,...... . ....... . ..... . .. . ..... .... 00 lb •• Useful Load ......... . .. .. . . .... ... ...•..................•........... JOO lb •.

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.65 to 70 m.p.h. 60 to 65 m.p.h.

to 2.!1 m.p.h • . per minute . per minute

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.... 32 ft • ....... 5 ft. 3 in • ...... . 168 .q. ft .

.. .... .. 400 Ib, • ..... .. 300 Ibs.

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filler is only pasted on. Too much heat will destroy the metal and weaken the joint.

Having the jig ready for laying in the tubing, curve the members to be used for longerons as nearly to shape i;lS possible to form the top and bottom lines of the fuselage. By curving the tubing. which can easily be done cold (do not heat)' there will be no sharp bends at the joints and the work will be symmetrical. Place the longerons in the jig. then cut and lay in aU brace members. Then spot weld and remove the assembly. Cutting off the nail heads will assist in re-moving the work. i!

As both ~ ides of the fuselage are identical, both may be built in the same jig. Now con­nect the two sides with the main cross mem­bers, both top and bottom, being sure to have them at the proper joints and both sides the same distances. Square the assembly by measuring opposite diagonal corners and getting both distances the same, Then put in diagonal braces. If proper care is taken the fuselage will be square.

Now fasten the fuselagl': solidly to th l': floor and proceed with tht' outrigger. This should be kept as nearly true as possible, but being wire braced, minor variations are readily corrected. Brace the outrigger with No. 10 hard aircraft wire •

The landin~ gear is built entirely of Va"x­I" squa re .049 tubing with the exception of

the axles, which are I" with Vs" walls round tubing. This gear is of very simple construction, and the plans are so clear that flO one will have any trouble with this detail.

The tail skid, which is shown in minute detail in the drawings, contains a I "x8" coil spring having a' pressure capacity of eighty pounds. In constructing, first build up both ends, put the spring in the upper end, com­press the strut, put in the bottom bushing. and weld as shown in the plans. The strut ~hould be left compressed until cool so as not to draw the temper from the spring.

In the next instatlment we will take up the construction of the wings. These are of the conventiona l spruce and fabric construction. so if you are able to go ahead with the fuse­lage. the rest will be easy, I f the welding is too much for your workshop, it will pay you to call in nn experienced welder. A good man should be able to do the whole job for you in two days; and you will be more con­fident when you take the air if you know that a workmanlike job of welding has been done .

Just a word of warning before you Mart building, If you haven't the price of an Aer­onc:! motor, or one of the other motors espe­cially designed for light planes, such as the Continental A-40 or the Bristol Cherub. build some other plane, Converted auto or motorcycle engines cannot be used,

BLUEPRINTS FOR TilE "FLYING BATHTUB" It TOU art!; eontt!;l'IlpIRtlnJ: balldln" tht!; "FI),lnlf natllfub" .ntl ,,'oul!! Ilk" a .e' of

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Building ~ The wings art of th

and fabric construction ahle to complete the wei rest should be easy.

Only sel~t spruce, pitch pockets. should b; It should have eleven to to the inch and should Th('re is absolutely no ! spruce in this work. ani tempt to cut the COSt a CliJ.r MtH._a(

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('"n'Jllele def,dl" ''I'' tile 'u'" tllnk '111,11 the ..... tlloll of lrIounth •• to tile win .. are a-Iven In t~l. workln.c dr,,,,-I,,... , '1111. tllnk I ...... de of .012 bu ..... d I ...... er .... wl'" ""It. Tit." ....... Ir .. eUo • ... U. tu .... I"".I ... · .... k ......... ". and It "'o"hl 10e .. , .... , ,., 'k ....... te .... bullll .... I. 'like 1101. Jott 1. , .... '_ftl U" .... I' .. , wllo will b"lId It for "', .. f .. m .. U,e ... dn",h.... /II' olft til., tit .. h"k ..... ,. lin III ...... n'p' .... lo .. _.rut. In tile unl ..... eetlon .. f " ... " 'In ... lind ,,,.t the ... , .... "' 1"." po"" ,,, ..... ·ere ..... lth ah, mlnllm III.' ....

Bllilding the Wings The wings are of the conventional spruce

and fabric construction. so if you have been able to compltte the welded steel fuselage. the rest shou ld he easy.

Only select spruce, free from knots and pitch pockets, should be used for the wings. It should have eleven to twelve annular rings to the inch and should be st raight grained. There is ab!iOlutely no substitute for aircraft spruce in this work. and one is foolish to at­tempt to cut the cost a few dollars by using Gild., M.naa'

cheaper wood. W~en in the air the weight of yourself. your plane, and your pllSS(!nger are carried by the wing. and the best material is none too good.

If the wood for spars is procured at your local lumber yard it is advisable to have it cut too wide and then let it season in a mod­erately, warm and shady place. so that in the event of slight warpage it can be cut and made true. \Vooc\ secured from an aircraft lumber company is usually thoroughly sea­som:d before being cut and sold.

The wing is double wire bractd with No.

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Complete def.ll. ot the .,.1" ... frut. nnll Iltlnchment flttln,,_ lire .. I,..," on tllllI pillte. All IItrllt .. !lire o. 1%,",..032 pUJ(1!! chrome .. ol7l:>de llum IIfeel tubln .... tre.mUlIed wit" rl~. 01 "''',.22 ••••• • 1 ... 1"11 .. lIoll1l1'",d to tlo ... trllt,. lind IIPllt-.:o1l nlnll! Illellell .rom eellter to eolllter. 'rhe_e lire e<;IVer. ed wltlll aIrcraft fabrll'l .ltd lIoDell. It 'helle .Crllt. are eon.UuCll'd .cellUlel,. )'ou WOJl" """!!! to ..... rn' .boa' tI.e anarle 01 "1I.,,k 01 Hie ..,Inp,:h. Ihl" .. ". l,e"" t .. k", .... nr", of 011 t"" .h· .... ln ••. • 11 half hard wire (market wire)', <\-rhe top and bottom wires pass through the edge of the span and cross behind the compression struts. .

To save work it is advisable to assemble the wing on a table to which blocks have been fastened in a straight line so that they will just fit inside the spars. This will en· able you to remove the wing from the jig true, if equal pressure has been put on the brace wires.

In assembling the wing, slide the wings on the spars to their approximate place.

Clld.r Manaal

Then put plywood reinforcements on at the fitting, joints and drill for fitting. The ribs may then be slid to the correct place and nailed and glued firm.

The jig for the wing ribs may be made similar to that of the fuselage, but it is bet. ter to layout the rib full size, from the di· mensions given on the working drawing, on a large piete of heavy paper, the paper being fastened to a Rat board of sufficient size.

The boundaries and keepers for the cap strips and diagonals should be formed out of rib stock. This rib stock may e;ther be pur·

89

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chased ready cut, or own shop by sawing! are a full quarter of all the rib stoc~ of Blocks. of the same (; should be nailed in at

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ribs becomes a simple is cut to proper size then the junction lJ(l

gusset plates cut from on with casein glue, at wire nails. When ( fastened together, re and glue and nail the junction points on the

All ribs are alike q ailerons. To change 1 ribs. cut out I lis" il rear spar. A half in the aileron spar, sho\ hind this cut-out on 1 diagonal pitces at this moved back proportior of the drawings will Ii to you.

IncidentaUy, the dil spar are not shown on spars (one for each wi stock. The depth of tained by measuring t :tirloiJ is laid ouf.

When assemblinz- 1 end aileron hinges con the spar. This is nc aileron from traveling

Till' Eml Thr various photOij

ship, r5r«iallr thr on this articlr. will give 1

Powered With Aeronca Motor, Ship Give. Exceptional Performance

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chased ready cut, or may be made in your own shop by sawing spruce into strips which are a full quarter of an inch square, Have aU the rib stock of the same dimensions. Blocks, of the same dimensions as the spars. should be nailed in at their proper places.

When the jig is once made, making the ribs becomes a simple process. The rib stock is cut to proper size and placed in the jig; then the junction points are covered with gusset plates cut from 1/ 16" plywood, glued on with cascin glue, and nailed with !4"x22 wire nails. When one side of the rib is fastened together. remove it from the jig and glue and nail the gusset plates over the junctioll points on the other side.

All ribs are alike except those forming the ailerons. To change the jig for your aileron ribs. cut out 1 !Is" immediately behind the rear spar. A half inch block, representing the aileron spar, should be then nailed be­hind this cut-out on your jig, the strut and diagonal pieces at this section of the rib being moved hack proportionately. A careful study of the drawings will make this detail evident to you,

Incidentally, the dimensions of the aileron spar are not shown on the drawings. These spars (one for each wing) are of Yl" spruce stock. The depth of all spars is best ascer­tained by measuring the openings after your airfoil is laid out.

When assembling your wing. have both end aileron hinges come inside the hinges on the spar. This is necessary to prevent the aileron from traveling sidewise.

The Empennage The various photographs of the original

ship, especially the one 011 the last page of this article. wili give you a good idea of the

external appearance of the tail surfaces. The working drawing of the tai l group wili show you everything you will Ilttd to know aout this part of the job. The entire empennage

OUTtR PVLLEY FOR AILERON-FOR CONTROL CABLE.

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INNER PULLtV ON FRONT SPAR

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SPARS TOGtTHt.R

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... . _MISCELLANEOUS DETAILS ... -R~QUIR~D FOR TH~ WINC;-

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91

.Comp/ete Detail. for Attaching Flying Strut. to the Wing Spar.

... DETAIL OF SPAR­"ATTACH FITTING FOR'" (NO VI(W .FRONT FLYINC STRUT'" O. FITTING

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txternal appearance of the tail surfaces. The working drawing of the tail group will show you everything you will n~ to know about this part of the job. The entire empennage is welded up of steel tubing, and if you don't forget the extra care whkh the smaller sized tubing will require in welding you should have no trouble with this work. There is little difference between the horirontal stabilizer assembly and the vertical-fin-rudder assembly save size and position. The stabili­zer and ruddor both have Ve"x.032 tube hinge hcams. while 5/ 16"x.032 and !4"x-

92

.032 steel tubing is used elsewhere, as point­ed out in the drawing.

You will find that the empennage will warp considerably where the light tubing is used, but with a little I:ardul che<:king and lining up by hand. bending cold. for there is little bending to be done. you will get a per­fect job.

There is quite a trick: to heating a steel tube in the proper place to get the right re­sults. Heat the tube on the side which is to be bent to a dull red. At first this actually increases the bend. but when the "tubing cools

Thi. Roon

off you will fin assumed an u to the original I most invariabl! exactly right.

In handling ing. extreme c taken not 10 g, too hot and b\ ing" It is eal

the weld is gO( 50 dean that II new metal had there the job I poor weld has I

on the outside scaly. If these up, throw that and build It ne1 is for this reasa vise that you cal c:r for a couple you can't do : yourself. The, could easily be I cost of the mate

The working this article giVe! of the control as is unnec~rr. assembly is for only onl! stick, \1

ter of the coclr.pi have the stick al

his legs. The I most convenient

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the Wing Span

the empennage will the light tubing is

checking and i cold. for there is

done. you will ~et a per-

trick to heating a steel to get the right re­

on the side which is to At first this actually

but when the °tubing cools

Thi. Roomy Cockpit Permila Side-by-Side Flying In Comfort

off you will find that it has assumed an angle opposite to the original bend. and al­most invariably come out exactly right.

In handling small tub­ing. extreme care must be taken not to get the metal too hot and burn the tub­ing. It is easy to tell if the weld is good. If it is so dean that it looks as if new metal had been placed there the job is okay. A poor weld has a sand effect on the outside and is very scaly. I f these faults show up. throw that piece away and build a new piece. It is for this reason that I ad­visa t11at you call in a weld­er for a couple of days if you can't do a good job

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yourse. e man s wages Keathm tor pla .. lnlJ the plYWDOI! Inatrament Itoard. could easily be less than the cost of the material you might spoil.

Controls The working drawing on the last page of

this article gives such a complete description of the control assembly that further comment is unnecessary. You will note that the pedal assembly is for dual controls. while there is onl)' one stick, which is rigged up in the cen­ter of the cockpit. The pilot. therefore. will have the st ick at one side instead of betweoen his legs. The gun should be placed on the most convenient sido for the one who will

usually do the taking off and landing. If duel control is not desired. one set of pedals may be omitted.

Rigging Both wing panels should be sot exactly

alike. The horizontal stabilizer should be leveol unless it is found necessary to correct for either nose or tail heaviness. Take plen­ty of time. get everything correct. and a good fl ying ship will be your reward.

Covering and Doping This procedure should be carried out by

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Side.by.Side Dual Control Mak e. "Flying Bathtub" Good Indructor

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the envelope method wherever possible, and the open edges hand sewed. Use three coats of dear dope and two of pigmented dope, applying the first coat with either a brush or a low pressure spray gun. Be sure the first

FRONT VIEW 0" ... SSEMBLEO

rlTTINGS

LOWER FITTING

"'COMPLETE DETAILS Of THE­"'CENTER-WINe ATTACH nTTINC'"

coat thoroughly penet rates and fills the fabric and that all other coats thoroughly cover. Doping should be done under fairly warm conditions and each coat permitted to dr}' before further application.

rRONT VIEW or PE-O"L,5

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ENLARG£D END "NO PARTIAL 'IOE VIEW

SUPPORT rOA THE CENTER BE"R!NG5

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SUPPORT FOR THE: -COMPLETE DETAILS OUTER eeARINGS -fOR fOQTPEDAL'"

-ASSEMBLV -

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t<,,,trates and fills the fabric coats thoroughly cover.

done under fairly warm permitted to dry

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