Introducing the 'EagleRay'

[slartibartfast]

Looks fantastic Doug.

 

Almost like a real Eagle Ray

 

 

[Thalass]

This looks great! Like a real little fighter. Where are you going to put the landing gear when they fold up? Could the nosewheel fold rearwards to sit under the pilot? Not the best direction for a nosewheel to fold, of course, but it might fit like that. And I suppose if the wheel itself still protrudes slightly, you could possibly land it glider-style if the gear fails to extend.

 

I was also going to say that if you have CoG problems with an engine in the nose, perhaps you could put an electric motor up front (small, light) with a heap of batteries behind the pilot to pull the CoG back towards the centre of lift. But then I'm biassed like that heh.

 

 

[Deskpilot]

Looks fantastic Doug.Almost like a real Eagle Ray

Got to ask, is that a natural photo or has it been photoshoped. Looks like a spinner has been added.

 

Hmmm, not sure about that colour scheme though.

 

Whilest we're on that subject, what scheme would you use...anybody?

 

 

[slartibartfast]

Don't think that's been 'shopped Doug, it just popped up on a Google Image search. It does look like a spinner though.

 

I'd go with the spots like the photo, but then I'm partial to spots.

 

 

[Deskpilot]

I found this whilst researching the colours of Eagle Ray.

 

I think this is the 'Human face' of the Eagle Ray. Uncanny or scary? I kid you not.

 

 

 

[Deskpilot]

Latest mods

 

Latest mods are:

 

New, sleeker cowl, extended and narrowed strake (front delta), height lowered on wiglets and fins plus fins shortened in length.

 

Just playing with colours at the moment. Nice to have the cockpit glazed and transparent.

 

 

 

[Guest Maj Millard]

Yes starting to look quite decent. However, (sorry to sound critical) I still don't like the wingtip shape, I'm seeing more like the Cheetah wingtip on it, a nicely curved winglet with some style. Unlike what you have there now The white one in your Avatar looks better to me...........................................Maj..

 

 

[Deskpilot]

The white one in your Avatar looks better to me...........................................Maj..

That's strange Maj, it the same one with a couple of inches lopped off the top. Anyway, I understand what you mean re shape but I'm sticking with mine fo 2 reasons.

 

1. It's a damn site easier to build. And

 

2. Have you ever seen a curved winglet on a fighter aircraft, I can't think of one. Eagle Ray, to me, has the appearance of a fighter. I just hope it's a tough little bugger.

 

Having gotten the shape about right, I'm now thinking about the method of construction. Got to keep it light, and costs down as low as possible. I looked at honeycomb f'glass panels but that's more than I want to pay at about $400 per panel, so I'm back to a wooden frame (can't weld) with either ply or glass skins. The problem with glass is that it will need more support than ply so any potential weight saving is lost. Is it possible to fix metal to a wooden frame? Hang on, I wonder if I could rivet aluminum angle to form a frame but still use wood for major support pieces such as spars and under carriage mounts? Any thoughts....anyone?

 

 

[Guest Maj Millard]

It's a pity you can't weld. Welding Chromemoly tube with Oxy acetelene is extremly easy once you get the hang of it, even enjoyable, and very satisfying to do. The metal flows like butter once you have the hang of it.

 

If I were to design and build again, I would definitly look at using square alum tube in preference to round. Lots of advantages, and not many disadvantages, and a hell of a lot easier at intersections using gussets etc. Most FI racing cars use square section metals as did the Etype jag for it's subframe. Strong as, and it would lend itself to your design..Maj..

 

 

[Skykid]

That's strange Maj, it the same one with a couple of inches lopped off the top. Anyway, I understand what you mean re shape but I'm sticking with mine fo 2 reasons. 1. It's a damn site easier to build. And

2. Have you ever seen a curved winglet on a fighter aircraft, I can't think of one. Eagle Ray, to me, has the appearance of a fighter. I just hope it's a tough little bugger.

 

Having gotten the shape about right, I'm now thinking about the method of construction. Got to keep it light, and costs down as low as possible. I looked at honeycomb f'glass panels but that's more than I want to pay at about $400 per panel, so I'm back to a wooden frame (can't weld) with either ply or glass skins. The problem with glass is that it will need more support than ply so any potential weight saving is lost. Is it possible to fix metal to a wooden frame? Hang on, I wonder if I could rivet aluminum angle to form a frame but still use wood for major support pieces such as spars and under carriage mounts? Any thoughts....anyone?

If you use cherry max riverts you might get lucky with it. But they do cost a hell of alot. Also I quite like the wing tip as it is. The boss (before he left) and I were talking about the advantages of the tips twisted up. Sadly it was about two in the morning so all I can really remember is that it makes the wing it a bit stronger and helped with reducing vortices. Please correct me if what I said was worng.

 

 

[Deskpilot]

For the past 2 weeks I've had visitors from the UK staying with me. These included a delightful, and clever 8yo boy named Thomas, and an 11yo girl named Ami. Now, to keep them occupied, we gave them access to our computers to play games only. Yesterday I decided to do a bit more modeling on the Eagle Ray and on opening the folder, I found a project named Thomas's House. Now, I didn't say he could go there but he made quite a good job of it. Remember, 8yo and Google Sketchup. I was quite impressed until, I found that he had deleted my ER latest model. Now I want to ring his bloody neck. Luckily he's back in the UK (landed 2 hours before they closed everything down)

 

Guess I'm going to be busy for a few days trying to rebuild it, if I can remember all the mods I did to it. Before you ask, no I don't have a back up as the pc had a minor crash and somehow deleted my restore points. Windows 7, agh, give me XP every time.

 

 

[Deskpilot]

Just a few pictures of the latest updates. The transportable fuselage and the method of fitting the fins. Please excuse the errors in the fin mounts, got the angles wrong somewhere. A bolt up from underwing and into the vertical spar does most of the anchoring but with screws around the fin sides. Probably another bolt in from the leading edge as well. Strong enough?

 

 

 

 

 

[Deskpilot]

Sometimes I am real dense. I made the fins removable as I thought they would be too wide at the tips for road towing. However, I just got round to actually measuring them and find that they are inside the stub-wing width (7.5 feet) and can therefore remain fitted. I think I'll stay with the mounting method though, never know if they might have to be removed at some time.

 

 

 

[Deskpilot]

Time for another update.

 

Sorry about the images being attached rather than in the post but I just can't get my Picasaweb URL to work. Anyway, what you have here is the final (I hope) configuration. I have moved the fins away from the fuselage due to the 'interference?' drag caused by their close proximity. They will now have to be removed for trailering as their tips are too wide.

 

Next, in order to see something more realistic developing, I have started on the cockpit construction details. I've think I stated right at the beginning that I would start this way so that I, or anyone else building a plane, can have some-where to sit and ponder whilst waiting for inspiration or the arrival of cash with which to proceed.

 

As you can see, the fore-strake platform comes first, to which is fitted the fire wall. The engine side of this is doubled with an alloy plate of the same dimensions. There will be ply and foam ribs mounted on the platform at a later date. The engine itself will accessible via removable top and bottom cowls.

 

Next comes the fore deck/instrument panel assembly. I am still developing what I really want but this temporary model will give you an idea into what I have in mind. I have positioned the ASI further away for the pilot so that it's close to his line of sight during the take-off and landing phases of flight. With the Delta, a much steeper, nose high attitude is required for landing and if you're not careful, a sudden loss of speed can dump you unceremoniously on the ground. Having the ASI so close to the line of sight, any speed reduction should be seen early enough to open the throttle and save the day.

 

Nothing much to say about the screen and canopy. Alloy frame and perspex 'windows'. I have thought that a little support might be needed in the middle if the screen so the ASI housing could double as the base for that as well. I want to be able to open the canopy for taxiing so I'm looking at having it lift and slide, or pivot up and back. The trouble with that is that the prop-wash might snatch it back too quickly. Time will tell.

 

Finally, a pilots view.....sort of.

 

Don't take too much notice of the colours, I'm just playing.

 

 

 

 

 

 

 

[Thalass]

This is a great insight into the sort of stuff you have to go through to design your own aircraft. I've been tempted to build my own tandem two seat amphibian lately, but one project at a time! (Mainly it's been images of kayaks with wings, so it's best that I let it simmer for a while to mature. haha!)

 

 

[Deskpilot]

Hi Thalass, yes, it is quite a procedure. Going by your trade status, I would have thought that you'd be more successful than I in our endeavors. Some time ago, I treated myself to Bill Whitney's DVD and notes on how to design an aircraft. Having viewed it I thought,that's straight forward and easy. Well it's not, especially if you go complex like I have. Bill's course notes are fine if you want another Cub look-alike but anything out of the ordinary, forget it. Mind you, they should work for your amphibian, if it has the normal layout of fuselage, wings and a tail assembly. I'm not sure how you'll go with the high thrust line though. He doesn't cover it. Shouldn't be too difficult to find more info on the web.

 

I haven't published every thing on this site but have more on Homebuiltairplanes.com A couple of images seen below for instance. I'm currently grappling with the Center of Lift (Pressure) position but I think I have to decide on my wing profile first, symmetrical with a touch of reflex at the trailing edge. This is a take it or leave it decision for me as no-one will offer a suggestion in case it doesn't work and I get hurt, = Litigation in their minds. One day soon, I will take the plunge.

 

Don't give up on your dream design, go for it. I am currently helping Skykid with his modeling problems for his own design, so join the club. That goes for everyone else to.

 

 

 

 

[Thalass]

haha thanks. I haven't really started any serious design. Just sketches when I have a quiet moment. But yes! One day I'll start. I've got too many house-related chores and an electric motorcycle to do first!

 

 

[Deskpilot]

Design update

 

Although I've been busy with life in general, I've still found the odd moment to try and improve my design. For some time now, I've been trying to model a reflex wing with a vortex generating undercut on the leading strake. The attached images will give you the basic idea. Bear in mind that 'I know nutting' bout aerodynamics 'cept what I read ... occasionally. If my theory is correct, at a high A.o.A. when landing, airflow will spill out from under the strake causing the vortex. This in turn helps to delay the airflow separation point just as V.G. do.

 

Whether such a long(cord wise) and slim profile will provide sufficient lift is anyone's guess although, a chap in the States has taken some info, and modelled it in some simulator or other and he tells me that my original symmetrical wing is stable, controllable but needs more power than I want to use. 'A bloody good first attempt' were his words.

 

 

 

 

 

[eastmeg2]

I do believe I saw the Concorde doing exactly that in Ch 7 last night. did you see it too?

 

 

[Deskpilot]

No, didn't bother. A few years ago, I sat through 2 dvd's of Concords flight from Heathrow to New York and back. It started with an in-depth walk-round and then followed the flight from all three cockpit crew positions. Every switch and lever was explained as were the crews independent responsibilities. This all came about as a friends son was the pilot. Before you ask, no the dvd's aren't on general release. Tell you what though, the crew didn't have much time to relax. Almost as soon as they get to height and Mach 3, it's time to start slowing it down again. Scariest point would be taking off from JFK and doing a smart left hand turn to avoid over flying populated area's.

 

 

[Deskpilot]

Been a while...

 

Due to other commitments, it's been a while since I did any work on my design. Having nothing other than reading to do yesterday, I decided to put in a bit of work.

 

Here are a few images of my cockpit construction thoughts. Mind you, I keep changing my mind as to the build medium. Wood is looking way too heavy at the moment so where I go from here is anyone's guess.

 

Sorry they're all attachments but I don't have them on Picasa.

 

 

 

 

 

 

 

 

 

[Gnarly Gnu]

I think timber still has a lot of things going for it (but not everything of course). You can strengthen your ply structure with bonded carbon fibre extrusions, they are quite cheap now. Also one can get 1.5mm thick ply pressed up, very light and yet quite tough. Of course timber is never going to weather as well as other materials.

 

 

[Deskpilot]

Hi GG, where the hell is 'Murray Bilge'?

 

Seeing as I'd be building under the Experimental category, I can use any material I like so as alternatives to wood, I'm thinking, for non stressed areas-the cheapest ally tube(square) I can find and/or f/g covered foam. For main spars, D section and gear attachment I'll stay with wood. Ribs maybe foam with wood caps. Skin with mixture or rag and f/glass dependent on weight prior to skinning. Ideally, I'd like it to be all f/g skins. There will be a fair amount of filler and glass at body, fins and wing intersections for fairing purposes. Winglets-f/g over foam.

 

Anyone else got some suggestions? Don't go steel, can't weld.

 

 

[Deskpilot]

Latest update.

 

Hi Guys, remember I posted another thread re Maths, well it's gonna have to wait because in my latest rendition of a reflexed wing, all angles and dimensions have changed. Ain't that just typical Anyway, I thought you'd be interested in my new alloy fuselage skeleton with proposed wings.

 

I've gone for square alloy as it'll be easier to join than round. A lot of it will be non-structural so doesn't have to be air-craft quality. Remember, this will be 'Experimental' and I'll be the only flyer. Sorry to spoil your fun.

 

The spar boxes (front and main) will be ply but I'm deliberating on wing construction. Spars might be wood although I have an idea using 'T' section alloy where the leg is tapered along it's length. Take 2 of them, invert one and plate both sides to form a tapered 'I' beam. Workable??

 

Ribs will probably be foam with ply caps except on the strake where they will be all wood due to the weight of a pilot climbing in and out. I'm not sure about including the ply base board previously shown due to weight, but I do like the idea for strength. Top surfaces will be ply and or f/glass so that the concave surfaces can be followed but the under side could be fabric for lightness.

 

You'll notice that I'm having trouble modelling the reflex. I can't get it to remain at right angles to the cord. This is due to the way that SketchUp works I think but I do need to find a way around it or else I won't be able to take dimension from sectional cuts. Time will tell. I know there are other programs out there but I really don't want to relearn how to model.

 

The turtle deck/back? will be f/glass and removable in order to get at the control runs if needed. I'm also going to put a large access panel under the cockpit floor so that I don't have to stand on my head to fix anything under the inst panel. Did I show you that?

 

I've decided against the retracts and contra rotating props.................for now at least

 

There you have it. Any comments?

 

 

 

 

 

 

[Thalass]

Great work! I can't wait to see it built.