Okay the good news is my brother and I put the maiden flight on his Y/A, A-4 OS-91/Ramtec- this afternoon... (previously used but not by us..)

After a couple of aborted takeoff attempts, and an incident with some mustard weeds , we got her off the ground but it took about 350'- even then, it was only because someone was driving into the parking lot (conveniently crosses the runway..) and I forced her up...

Yatta, yatta, Through my reading I noticed most folks with this combo get up before 350'- we had it set-up nose high (5-10 deg.) and it has the cheater hole in the wing... the 91 was screamin'

Any thoughts? For you San Diego folks, we were once again flying DF at the Weedwackers in Lakeside

So far:

TGA F-15 2 takeoffs with 1 landing
Y/A A-4 1 Takeoff with 0 landings

BTW- The bad news is another dead-stick at show center going say... 120? More bushes is the bad news-

looks like you have some soft tires installed???, that is definately a contributor to a crappy takeoff roll! What is the weight, is it the new or old version?

Chris

Razor,

Last weekend I helped a friend get his Y/A A-4 (Dynamax & OS .91) up for the first time. It did take quite a bit of pavement before rotation and I know we had the engine setup right and on the pipe. It was screaming straight down the runway perfectly, but it just took some time before it reached flight speed.

So you probably are not doing anything wrong, you are just going to need that much pavement to get it off.

It flew great once in the air and it slowed down really nice for landing. The short gear stance made it wobe and scrape the wing tips a bit once we got it on the ground. We will be flying it again this weekend and I'll see about measuring the take off roll.

JR

I put a RAM 500 turbine in my Y/A A-4, it has no problem rotating off grass. I have video of the takeoff, can someone post it here on RC universe?
Chris

HI !

I HAVE THE JHH A-4 WITH TURBAX AND KB 7.5 .AND TAKE OFF
IN 250. AND ITS A GREAT TRAINER( MY FIRTS JET) FIRTS IF YOU HAVE A CHEATER HOLE IN THE WING , YOU DONT HAVE THE YELLOW ONE ,YOU HAVE THE JHH. I HAVE NEVER SEEN A YELLOW ONE WITH CHEATER IN THE WING , BECAUSE THE WINGS ARE PLUG IN THE FUSE .THE .91 NOT NEED IT..IT PERFORMS BETTER WITH OUT IT . THE CHEATER HOLES ARE FOR SAMLL ENGINES .46 THA A-4 FLYS BEST AT 10 POUND AND TEND TO BE OVERWEIGHT WITH THE .91 AND ALL THAT FUEL. HOW MANY ONCES OF FUEL YOU ARE CARRING ?
WERE ARE LOCATED YOUR FUEL TANKS?. FIRTS I USE A 24 OZ IN THE NOSE IN A PLYWOOD PLATE UNDER THE CANOPY AND THE PLANE BECAME VERY NOSE HEAVY DURING TAKE OFF. IF THAT YOU CASE USE 2 11 OZ DUCTED FAN TANKS NEAR THE FAN A CG.
DO YOU HAVE THE 40 OR 45 INCH WING. IF YOU HAVE THE 40 AND .91 SIZE ENGINE I THINK 350 FTS ARE NOT THAT BAD

PECOJETS

A friend of mine started out in jets with a YA A-4 with a Dynamax fan and OS.77, back in about 1989. We were flying off a 225' runway. He had no problems at all getting it off. It did run off into the grass sometimes (depending on wind) but would still rotate and fly out fine.

I suspect that the Ramtec fan may need more inlet air than you can get, even with the cheater. The Dynamax fan may work better in that application. As I remember there was no cheater on the OS.77 powered one, but YA recommended a cheater hole through the nose gear opening on the OS.91 powered one.

BTW Razor, your pipe is on the way.

Razor,

Well, you've got more sack than I do flying that jet out of Weedwackers! I was scared to fly my Starfire there, and it got off in about 85' with flaps and a BVM engine/fan!

Is it fixable? If so, fix it and give me a call. I know a better place w/o horses, influential zoologists who don't like planes overhead, or any of the other trappings of Weedwackers. Actually, it's a nice club with nice folks, but I don't think it's the best for jet ops.

I'd still like to see your setup, too.

perhaps with the cheater hole in the wing , there is a vacuumn effect taking place sucking you to the ground. A friend of mine had the Thor Bro. F20 and had this problem. Maybe you may need to chop the throttle and at the same time have in some up elevator to help you rotate. Just a thought.

I do not know the weight or if it is the old or new version...

Chris wrong fan unit? No idea what you are talking about...

I was under the impression that the cheater hole is not a part of a kit but something done by the customer-

Shaun, Yes it is repairable the nose is just wrinkled... The 91 was funky, we could go 2 full turns lean or rich with no noticeable difference in RPM or mixture (smoke?)

During the lowest pass of the test flight (25 ft.) the hatch decided to leave the jet.... Dunno if that cause the flameout but 1/2 cuban eight later it was deadstick show center...

Flaired into a bush- easy fix! (one guy said you should have glided over and landed on the Polo grounds :stupid: ) yeah corky...

Thanks for all the help folks, and Shaun I will let you know when she is ready again!

Can you PM me with the club that is DF friendly? :thumbup:

james

Had 2 of these. Flew them out of a 200' paved runway.

Things to look for:

- cheater hole, 6 sq in minimum, base of inlet ducts, uses nose gear opening for aux air.

- Nice smooth inlet at the outside of the fuse. No ridges!

- Inlets not collapsing when at full power

- Exhaust tube and duct work fits well with no leaks

- Engine is truly turning 23k+

- Fan rotor not slipping

- 10% Ducted Fan fuel (not sport fuel)

- Hard tires not spongy soft

- No drag on the wheels - spin freely, well greased

- Model weighs 10 - 11 pounds dry or less

- Fan rotor has minimal clearance to shroud and clearance is same all around

- Engine piston sleeve is properly oriented not rotated so timing is screwed up

- No fuel restrictions (like kinked line, dirty needle valve. . .) - need all the RPM you can get

Bout all I can think of now. Let us know what you find

I've had three Y/A A-4s. All had Dynamax fans. The first was with the scale wing, 13lbs, Webra 80, and cheater hole thru the front of the ducting to the nose gear area. Takeoffs on hard surfaces were about 300ft. You needed to use quite a bit of power on approaches as power off landings (or deadstick) were like a brick.

The second one was the sport wing, OS-77, and same type of cheater hole. 250-300ft on T/O was normal. A much better glide to landing unless you let the nose get too high. This A-4 had the A-4 quirk of when you rotate on takeoff, you need to avoid over rotating and pulling the nose up too much, as the A/C will climb out vertically (for 50-100ft or so) even with full down, as the tail gets blanked. There is no recovery for this if it happens on takeoff.

I witnessed one go in a Woodland a few years ago, over-rotated, climbed out to about 75ft, flipped over and went in directly on the nose.

You can recover from this if you have the altitude (300ft or more), if you go hard over on the rudder and ailerons and roll the plane on it's side. The nose will drop after a few seconds and recovery is then initiated. I learned this the hard way. It's exciting when you are holding full down and the nose keeps rising. This was after a gear pass, and I raised the gear, powered up and started a steep climbout........steeper than I liked!!

Have other people experienced this?

My third A-4 has the sport wing, K&B 82, 13lb, and the cheater hole that has the bottom intake behind the nose gear opening. This was somebody's after-market intake system, I forget the name. It will use at least 400 ft before it rotates off. With full fuel, it's a bit nose heavy, and I attribute the long T/O roll to this. I didn't think that the bottom intake would be sucking it to the runway, but could be. I also have fairly small wheels on it, and invariably blow off the nose gear tire when landing, as being a bit nose heavy, it's hard to get it slowed up by raising the nose and letting the airframe get into the nose high drag mode.

I've always enjoyed the Y/A A-4, as it's still a great flier!.

Hi,

Yes, I've experienced that over-rotation too. It was on the older kit; scale wing. As it turned out, it was always because I was running out of runway and went full elevator. Due to the inefficient inlets and rubbing tires, it just couldn't get fast enough for a smooth climbout.

The new kit's improved inlet has totally eliminated that problem. You can take the plane off in less than 300', even at 15 pounds, with a very smooth rotation and climb-out.