own design 95.10

[Guest micgrace]

Currently designing 95.10 all aluminium low wing taildragger.

 

MTOW 270Kg cruise around 70 knot (rotax 503). VNE 95 ( any higher requires mass balancing, more complexity) estimated 35 - 38 knots (no flaps, 28 -30 with). If intersted some design notes below.

 

Anybody else out there having a go at their own design???

 

It's more complex than I thought, between what you want to do and what is practical and easily and cheaply created.

 

The largest design challenge by far is keeping the structure simple (quick to build), while keeping parasite drag to an acceptable minimum.

 

Also to include, the wing profile to be easy to build and nice safe stall characteristics)

 

has to be basically retangular in plan form. I would go for an

 

elliptical planform, but think of how many different form blocks would

 

be needed (24 est. versus 3, they can be reversed), plus washout etc

 

However with a simple box structure, and some simple formers the

 

fuselage can be made relatively streamline, while using angle and skin

 

to transfer secondary loads around.

 

Could pick up some spare thrust (very small amount, better than drag)) by using an inverted enginemount, and redirecting the airflow under the fuselage. (Free Lift???)

 

The dragiest part will be the firewall (redirect airflow), canopy (open) and landing gear (although with the design of the landing gear will counteract yaw by a small amount).

 

I thought of several different solutions to this, but with this weight

 

restriction, the best solution is to distribute landings loads over 6

 

points on the fuselage, rather than, say, use vertical landing struts

 

in the wings ( increasing as much as twice the mass of the wings, with little corresponding reduction in fuselage mass.

 

Best to put up with some increased drag in this area.

 

The fuselage breaks down into 3 sections. Nose, centre, tail Centre

 

section doubles as a ROP system, with the other two sections would

 

crush in a crash. Designed to have no welded components (simple forms), minimum steel, minimum solid rivet use (except spars) Ease and speed of build.

 

Basically quite possible with engineering, physics, ultralight background.

 

Any comments, suggestions a suggestion for a name??? Still a long way to go.

 

 

[pylon500]

Do you have a scanner or cad package that you can upload a three view drawing of your idea?Some thoughts;I was getting 70 kt cruise from a 503 in a large, strutted, highwing, all aluminium 'Bird-Dog' lookalike (see my avatar)I keep my VNE to 85 kts 'cause I've never done any calculations for it!My stall is around 32 clean at idle, but with flap and power, I can maintain level flight at 27 kts!What I'm saying is...Aim higher!!Free Lift? Remember, lift is generated on the TOP of a wing, you'll get more lift with the airflow over the top.Why should your firewall create drag?If you cowl the engine and round off corners at the exits, drag should be minimal.To cut down on some of your start point research, have a look at some plans of other similar layouts and improve from there.Try the Hummel Bird.Feel free to pinch some structural ideas from;http://www.pbase.com/pylon500/rootArthur.I still can't get some of the HTML to work!? :-(

 

 

[Ultralights]

i believe there is a way to get a small amount of thrust from engine

 

cooling design, i believe there is an examply of a Vans RV7, or

 

similar.. the general consensus was that the engine cooling outlets are

 

20% larger than the air in ducts, this was to allow for heat expansion

 

in the air as it passes over the engine, the changes made to the RV

 

were to reduce the cooling outlets to 70% of the inlet, causing a

 

higher pressures withing the engine compartment, giving better cooling,

 

then designing the outlet to be round, running the exhaust outlets in

 

the centre of the circular outlet, anad designing the fairing around

 

the outlet to cause a venturi effect, so with the venturi effect from

 

the cowl shape, and exhaust outlet, the net result was an increase in

 

airspeed, better cooling and a lot less drag.

 

 

[Guest micgrace]

My 95.10 plans are paper drawn and calculated, far too large to get

 

into a home scanner. By the way, anything that sticks out in the

 

airstream, internal, engine, firewall etc creates parasite drag.

 

This effect (meaning engine and attached components) is well known in formula one circles, with vast amounts of data and research to gain the slightest edge.

 

At the end of the day, in the process of creating lift, drag is created, this being the largest component by far (in surface area)

 

I'm

 

only using a basic clark Y airfoil, with simple hoerner wing tip so

 

this tends to limit cruising speed the most. This being flat bottomed

 

is simpler to build.

 

As for estimates of cruising speed,I was

 

thinking of revising upwards to around 75 - 80 knot however I don't

 

want to get into mass balancing zone area (99 knot)due to my MTOW limit (more mass)

 

As for creating some positive "lift" (technically not lift as pointed out)

 

using some engine thrust from cooling air this has been used in some

 

warplane designs. This makes use of some energy that would be wasted

 

otherwise (airflow through engine cowling from propeller thrust, not foward airspeed). The end result would probably result in no more than 200N at full power (this would need to be determined experimentally)

 

I'm aware of the RV6 cooling duct design (not simple to construct), however I think I will arrive at a simple and lightweight solution to this design challenge.

 

At the end of the day, anything in this category is a mix of compromises /mass/ drag/ lift /design and build complexity etc.

 

My main design bias is simple, low cost to build, no welding ( I don't have anything against welded tubular airframes) extra low airframe maintenence. This requires a somewhat less than efficient aerilon/rudder/elevator attachment by piano hinge(some added drag that a more sophisticated hinged design would avoid)

 

I

 

mentioned to a flight instructor the other day, if you took out the

 

american designed/ redesigned / modified ultralights there are not many

 

truly Australian designs left. However, since homebuilding (experimental) here is now at least we will begin to see some truly australian designs, which is good for us all.

 

By the way, my favorite ultralight for general flying is the Drifter. All for now

 

 

[pylon500]

All basically makes sense, the Clark Y has turned out to be a

 

fairly good compromise all round, although your reason for using it ie;

 

simple to built, is actually limiting you a little.When building a wing, we often like to set it up on a table to get it square (or block up the trailing edge for washout)

 

but when you think about it, we only support it on the spars, therefore

 

the flat bottom on the leading edge ribs is not required mechanically

 

and is detrimental to aerodynamic preformance at speed.Basically

 

at higher speeds when the camber line starts to dictate a low or even

 

negative angle of attack on the chord line, you start to get flow

 

separation under the wing causing drag.If you go to a Clark

 

YH with a raised leading edge profile, you get better top speed PLUS

 

you can end up with a more docile stall.From what you've

 

posted maybe you want to build a metal version of Mike Arnolds AR-5,

 

maybe have a look at some of the Davis series of lightplanes (DA-8,DA-9 and on)Arthur.ps, Try to keep all your posts in the one thread, the administrator may relocate this with your original post if you pm him.

 

 

[Guest micgrace]

My 95.10 plans are nearly finished, except for possible registration drawings, bolt sizes, material quantities, assembly plans.

 

Have

 

increased wingspan slightly area slightly over 10 m2. and added some

 

refinement to the aerodynamics, without altering the basic design brief

 

(that being, simple to build, low maintenence, easy to fly, strong/robust. Othewise I'd just do something similar to the AR-5 (amazing)

 

It would be classed as half way high drag / low drag. (mainly to keep speed/handling near the design limit) The extra wing area won't go astray, as now I can include an additional payload of 25KG (fuel or luggage etc), plus pick up some added aerilon.

 

it won't be the prettiest design, (spitfire I reckon is), but will be fast (not airspeed)and cheap to build, mainly angle and flat, 6061T6 with a minimum of form blocks, basically stressed skin above wing (excluding engine mount and load transfer path).

 

Build make take place next xmas/ new year, it's now back to the grindstone.

 

 

 

[Admin]

Mick, please let me know when you start to build it as it would be good

 

to have your story and pictures here in the aircraft section of the

 

website.

 

If anyone else is or knows of someone building a kit

 

also please let me know so we can include as many stories as possible

 

on the site.

 

 

[Guest micgrace]

Hi guys.

 

Still not 100% set on design. My son wants it as a 2 seater. He will be going for his TIF and training once he hits min. age. 6 months and counting, him, not me)

 

So, back to the drawing board. Since my original design had the pilot at mid point CG It is easy to convert. After some reasearch a suitable engine is available (see engine post)

 

The design changes are, reduce front fuselage length. Strecth rear fuselage. Done to accomadate CG changes from heavier engine.

 

Change cockpit height. Since the fuselage/cockpit is now shortened the pilot will have to sit higher to be comfortable.

 

Some changes to the aerilons linkage to accomadate extra width. Plus changes to material specifications plus more braces in cockpit area.

 

Result of changes, using 10.87m2 wing area Stall est. 35 knot MTOW Cruise 75% power, using a 58 x 42" pitch 75 knot Vne 95 knot

 

But now to MTOW empty (with engine) 195kg + 30kg fuel (max) + 200kg pilot/passenger (max)+ 20kg luggage (max) = 445 kg MTOW

 

Sufficient fuel @ 10lt/hr for 4 hours.

 

Why can I get it at this weight? Use 4130n steel tube (gave up the idea of square)triangular braced everywhere 50m only 26kg Plus a more modern fabric approach.

 

I think this is quite a sensible approach to the problem of an affordable homebuilt, designed aircraft.

 

I will be documenting everything so full plans, materials lists, building instructions, pilot instructionsetc will be available after all requirements are met.

 

Micgrace:)

 

 

[Admin]

Michael - Correct me if I am wrong but there is NO minimum age for training other then going Solo so your son could start training now. A student could potentially have clocked up many hours training and be a very experienced pilot without any solo hrs, then when old enough, just do their solo hrs and sit their test.

 

 

[Guest micgrace]

Hi Ian

 

The particular instructor concerned (Caboolture) will not take a child for training until 14 1/2 then only for 1/2 hour every fortnight till 15 and then it's full on.

 

There could be some CASA applied rule as regards minimum training age, but I'm not aware of any apart from the 15th birthday.

 

Could be interesting for him flying long before he is legally allowed to drive.

 

If he does the right things, I suppose he could go solo on 15th birthday.

 

No doubt he'll want to fly daddy's (hopefully) newly constructed plane.

 

Micgrace

 

 

[Guest micgrace]

Hi all

 

My 95.10 project is underway. All aluminium construction, with fabric. Mid wing mount, open cockpit.

 

Have completed the basic centre section. (rectangular box) Will then fit the primary strucure into it , then begin tail section and then join together. Very heavy use of rivets in construction, 300 placed so far.

 

Long way to go as this is totally scratch built and and self designed and funds dictate the speed of construction.

 

Once it begins resembling an aircraft, rather than an overgrown fish tank I'll post some photos.

 

My son got to do a TIF in an Allegro and loved every minute of it.

 

Micgrace

 

 

[pylon500]

Sufficient fuel @ 10lt/hr for 4 hours.

Unless this starts to look like a motor glider, you will be doing well to get 14lt per hour from a 503.

Have you had a go at creating it in X-Plane?

 

Dont bother to count the rivets, you'll use plenty more!! ;)

 

Arthur.

 

I'm still working on the paintwork bitmap. :;)2:

 

 

[wanabigaplane]

.

 

95.10 ??

 

Micgrace - if the own design aircraft exceeds 300kg you are looking at 95.55/1.5, right?

 

A group of us in Canberra have started out on a project that began with the PIK-26 (google it) and, like the old axe with a new head and new handle, we have our project:

 

Flat sided laminated chipboard female mold for fibreglass fuselage, using vacuum bagging

 

Al spar, PVC foam ribs, Al skin glued on with rivetting at the spar

 

Half VW engine, full case, hummel 45HP design, wasted spark electronic ignition on crank, conventional carbies (so afar)

 

:)

 

 

[Greg]

Hi Folks, I'm also looking at own design 95.10 in this case wooden construction cranked delta, no drawings yet, only notebook sketches but the big hurdle from my point of view is doing the stressing. I have a couple of books on homebuilts which give you rule of thumb type approaches but it is hard to work out what forces to apply under different flight conditions - any suggestions would be appreciated.

 

I could use the TLAR (That Looks About Right) method then when completed, load it to design limits and hope that it doesn't break but if it does, a lot of work would be wasted!

 

Regarding scanning large paper plans, I used an old door, cut out a space for the scanner so that the scanner was flush with the door surface and scanned some large DH2 plans on my A4 scanner then stitched the resulting images (about 18 per drawing sheet) together using Paint Shop pro, this allowed me to rotate those images that were misaligned or inverted. I found that some of the photo stitching software available needed too large an overlap and didn't work well with line drawings. If you want to go the whole hog, in many CAD programs, you can import a raster image and then in another layer, "trace" over the drawing to produce a scaleable vector image but I haven't tried that myself yet.

 

Cheers

 

Greg