RC DeltaGliderIV project

[RisingFury]

Sure, I'll be careful.

One the sim I'm very reckless, but in reality, I fly 3 mistakes high and very careful. And it will take me no less then a few hours on this thing, before getting a bit more daring

Thanks for the concern.

 

[Sky Captain]

I`m looking forward for first flight:thumbup:

But beware of plane eating trees. They have tendency to jump and snatch your plane out of the air.

Also don`t forget to hail before takeoff.

 

[Dambuster]

Tis' true, in a WWII air combat sim I play, it's an oft-stated fact that the trees have the highest kill to death ratio of anything in the game

 

[Dig Gil]

LOL
"Pilot, watch that tree!"
"But there's a MiG right behind us!"
-2 seconds later-
"Where's the enemy's left wing?"
"In the same place of our rudder; I'd wish we were flying a delta wing..."

 

[RisingFury]

Yea, well, after landing my trainer in the tree twice and landing my free flight A-1 model high in the tree once, I get shivers when hearing something like that :lol:

 

[RisingFury]

Hello there beautiful! What's your name?

Last pics of 2009.

I've been busy. Since the last upload, I've made a lot of progress. The entire skin is glued on and some finishing touches have been added.

Here's the cabin:

I glued and screwed in the engine mount and covered it over with balsa. I also figured... can't have a foto-op without no prop, right?

I spun the prop with my hands as fast as I could and it makes a real nice sound! Can't wait to hook up the electronics.

I also covered over the air intake and made a nice smooth transition from balsa:

The hole is where the front gear will come out.


Anyways... that's it for 2009. It's been a nice build so far. I estimate I'll have spent 200 build hours by the time she's finished - ignoring the research and blueprint drawing.

The next set of pics I upload will have the DGIV fully covered in foil. There are only two major things left to do, asside from tinkering. Covering her up in foil and building the landing gear. I rebuilt the front shock absorber because I wasn't sure the last one would do the job well enough. The main landing gear has yet to be built.

Other then that, I had to tinker around - glue in the servo tray, solder the connectors to the speed control,... stuff that can be done in one day.

Before I have the girl fly, I'll try the thrust of the engine by borrowing a 5 cell and 6 cell batteries. I'll check which one gives enough thrust at a max of 50 A at full throttle. The engine is rated for 20 volts. 5 cell battery is at 18.5 V, 6 cell battery is at 22.2 V, but the actual current is deppendent on the speed of rotation, because the coils in the motor resist the current via induction... so have to do some measurements at full power.

Anyways... that's it for now.

 

[Arrowstar]

Awesome! Looks great. It's a shame the prop isn't transparent, but such a minor detail is trivial. And, of course, if you're hunting for modifications later, little smoke trail generators out the back might make a nice rocket engine exhaust stimulant...

 

[Brycesv1]

if the current is dependant on the prop speed, wouldnt you have some overcurrent (not sure if thats a word) being generated if you went into a dive? i think that would not be good for the engine.

 

[RisingFury]

if the current is dependant on the prop speed, wouldnt you have some overcurrent (not sure if thats a word) being generated if you went into a dive? i think that would not be good for the engine.

Well, of course it's not so simple...

There are many variables, but in general, as RPMs increase, current drops. So in a dive, the current would get smaller.

Also, current is greatest if you grab the plane and don't let it move. The reason is that the resistance is greater and prop slower.

Also, if you decrease the radius of the propeller, there will be less resistance. RPMs will increase and current will drop... so there is some flexibility.

 

[Brycesv1]

aah ok i see. thanks for clearing that up

 

[Dig Gil]

RisingFury, doesn't the propeller's location inefficient? AFAIK, the propeller pulls air from the front and pushes it to the back of the plane, as you know, but a large area of it has its front almost covered by the fuselage.

 

[cinder1992]

Maybe, if the prop turns out to be insufficient, you could add a ducted fan with the intake where the air intake on the DGIV is (also, a pair of engines on the back would be an nice aesthetic quality).

 

[RisingFury]

RisingFury, doesn't the propeller's location inefficient? AFAIK, the propeller pulls air from the front and pushes it to the back of the plane, as you know, but a large area of it has its front almost covered by the fuselage.

Yes, that's true.

It's tough to predict what exactly's gonna happen though. Most of the thrust is produced on the outer edge of the propeller. I suppose the inside is gonna experience slightly less drag, enabling the prop to spin faster and at that point, the outer parts would compensate.

Though I don't think there's an analithical solution to this setup... you'd have to model the airflow around the back of the body.

EDF is out of the question. If I find thrust to be insufficient with a 5 cell battery, I can increase to 6 cell if current permits. I could also increase prop size and lower pitch,... we'll see.

 

[Dig Gil]

Better use smoke in a wind tunnel .

BTW: Do you know a source of knowledge about propeller design? I'm interested to read about it.

 

[RisingFury]

Better use smoke in a wind tunnel .

Well, if I had access to a wind tunnel... that'd be sweet

I will try to make a small one at home so I can test individual parts of planes in the future... but I need to figure out a way to produce smoke without dropping a smoke bomb... It would be nice to have something that pops smoke out of a small tube, like they do in the real testing.

I still have to do the test on the nose. I figured it would be useless doing it before the thing is covered in foil. Foil is smoother and produces less turbulence.

BTW: Do you know a source of knowledge about propeller design? I'm interested to read about it.

I'll have a look around for some documentation...

 

[Zatnikitelman]

Maybe try blowing talcum powder through a tube or somesuch. When I played with it years ago, it always produced satisfying smoke!

 

[Donamy]

Looks impressive ! Could we get something in the pic for scale ? A can of coke pehaps.

 

[Arrowstar]

Well, if I had access to a wind tunnel... that'd be sweet

I will try to make a small one at home so I can test individual parts of planes in the future... but I need to figure out a way to produce smoke without dropping a smoke bomb... It would be nice to have something that pops smoke out of a small tube, like they do in the real testing.

Use theatrical smoke and draw the gas through a series of small diameter pipes. You'll need to heat the smoke fluid until it goes gaseous, and I can investigate the mechanism that drives the smoke into the test chamber if you'd like (but I suspect it's just low pressure in the test chamber). We use this set up at my university on a small smoke tunnel and it seems to work well.

 

[RisingFury]

Use theatrical smoke and draw the gas through a series of small diameter pipes. You'll need to heat the smoke fluid until it goes gaseous, and I can investigate the mechanism that drives the smoke into the test chamber if you'd like (but I suspect it's just low pressure in the test chamber). We use this set up at my university on a small smoke tunnel and it seems to work well.

Oh cool! That might do the trick!

 

[Dig Gil]

Arrowstar as made a good post, being the "theatrical smoke" dry ice (CO2) when vaporising, it's a bit too away off the KISS concept. I was thinking about burning dried grass (straw and chaff). Also, I once noticed that if you burned candle wax after heat it up to the point of melting, a heavier-than-air smoke is produced (probably it's rather an aerosol than a gas, I dunno).

---------- Post added at 12:00 PM ---------- Previous post was at 11:27 AM ----------

I was burning my time.... I mean: some stuff and concluded that:
-Newspaper makes a grey smoke if not in flames (just incandescent).
-Matches only produce white-ish smoke after and before being lit.
-Rubber (I used the one that warps copper wire) makes a lot of white or/and grey smoke, unless it starts to become carbonized.
NOTES: couldn't find any straw due wet weather.