Tempest Mk II test flight # 2 - Oh Oh!

[Ron Daniels]

I test flew the Tempest Mk II with my new Astro 05 G set-up yesterday.

I had the air to myself, thanks to flag-snapping winds and 40º temperatures.

We took a couple of pre-flight photos.



My wife had never launched one of the Hawkers before, and commented on how surprised she was that it just flew out of her hands, after a couple of quick steps (She's much more used to launching rubber powered free-flights). She didn't say it, but knowing how she feels about oily glow planes, I think she liked not getting her hands oily, as well .

I found acceleration and top speed better with the new set-up. It is an old 7 t 05G, 2.38:1, 10 cells, M/A electric series wood (undercambered) 11 x 9 @ 6300 RPM. Climb rate is substantial with this set-up, and 1/3 throttle cruises are still solid.

Except for my cold hands, I did not notice the wind whatsoever, even when flying at 1/3 throttle.

Here's a shot of the Tempest coming in for a medium altitude pass. As you can see, camoflage actually does work! This is why so many of my other warbirds wear stripes.....



Here's another shot on high fly-by. It was not a good time of day for lighting, but the forcast called for possible snow flurries later in the evening, so we went.



Then it started....

I lost contact completely with the airplane while high and upwind about 200 yd, and it just continued away from the field. I had the presence of mind to raise my antenna stright up over my head, and this got me back control, but there seemed to be a motor failure, as the airplane just acted like it was gliding.

I landed it down a hill, and out of sight with a very loud CRACK!.

When I got there, it was in a small tree with one section of the outer left wing panel caved in. Luckily for me, the wing tip remained attached, and this will make "filling in the blanks" an easy route of repair. I figure that I've got about 1 hr of framing repair (with about 1/2 of that time to ensure allignment), about 10 minutes of re-covering, and, very little time painting, as I have to use all the same colours to finish a different model very soon, anyway. There waas not even a scratch anywhere else on the plane

It is disappointing, though, as I was really enjoying the flight, and a certain hand-launcher wanted to try out the Tempest as well. I really wanted to see what it would do with my lighter, higher capacity 1300 pack. I guess that will have to wait....

Back at home, I decided to beat myself up over this, by assuming the power loss was due to my dreaded BEC thermal overload cut out. So I placed the fuselage on a stand, and ran 1 1/2 packs thorugh it at 1/3 throttle (remember, ESC's get hotter at partial throttle than full) without cool-down between. Not a moment's hesitation from the motor.

This morning, the 20/20 hind-sight kicked in.

After I regained radio contact by raising my antenna, I failed to re-initialize the ESC. While I pulled the throttle back and forth to try to get the motor to start, I did not pull the trim back to zero. Had I done so, I could have easily climbeed the plane back to a safe landing area and said "something's wrong with my radio" let's go home.

Before September of last year, I had never had a radio related crash. Since then, I have had 2, with 2 different receivers, both with my trusty computer radio. The first was in an area of high potential interference (NEAT fair, 6-7 other planes in the air). I upgraded to a JR min-reciever from the GWS micro that I used there.

Now, after re-gaining control by raising my antenna high in the air (maximizes range for a given signal strength), I am beginning to suspect that my transmitter is putting out either a weak signal, and intermittent signal, or that the frequency has drifted a hair off of center. Intermittent is not likely, as I got hit in a certain point in space twice at NEAT, and one would expect an intermittent signal to be more random.

My transmitter will be sent out for testing/repair this week. I won't be able to fly a few of my planes until I get it back, as my only other one is a simple 4 channel. Oh, well, it will give me time to fix the wing!



Ron Daniels

[CraigO]

Ron
glad to hear that the tempest is not a complete loss.

just a thought, are you running a shottky diode on the motor?

I just purchased a new schultz controller and it said in large letters that a shottky diode should be installed to reduce heating of the controller from back EMF and to reduce radio interferance, particularly with twin engine configurations.

I didnt believe it to start with and so i tried my twin engine mozzie with the speed controller loading it to about 1/2 power and the speed controler was quite warm even after a only a minute or so. So i installed a couple of shottky doides on the motors and now it hardly warms up at all. so now i am going to install them on more of my models.

any thoughts?

Cheers

Craig

[Ron Daniels]

No, I'm not rudnning a Shotkey diode.

My GP 50 A ESC had one, but this one does not.

When I deliberately abused it with my bench testing above, it did not even get uncomfortably warm to the touch.

Also, some extensive range checking showed some glitches on the ground today, even with the motor not running.

My wife suggested that I buy a new transmitter, but I think that may be extreme. For now, until I know what is causing this, all my channel 52 planes will be on the ground.



Ron

[dottney]

Anybody know where you can buy Schottky diodes. I'm having a devil of time finding them.
Dave

[temacc]

dottney: Call Pete Peterson at MEC for Schotkey doides (sp?)

Rod - Have you seen the latest issue of the English mag,
"FlyPast"? Has a center section foldout on the Tempest,
and several articles, many pix of several.

NICE model! Want to build me one? (I have a 7-channel Futaba Xmtr to trade, even have a little cash, too)

Terry

[mrittinger]

All I have are "Regular" 4 channels!
Whats a computer radio?
Makes you as better pilot, does it not?
Mark

[Ron Daniels]

Hey Mark!

I don't know if it makes you a better pilot, but it gives you more buttons to play with as you crash your airplane into something harder than it is!

I'm glad that it wasn't the BEC that caused it. With my inisitance on using a BEC, I would deserve a severe "I told you so".

I'm getting the transmitter checked locally for signal strength and frequency, and if it is off, I will send it to the manufacturer for re-tuning. One friend suggested that an intermittent power output could be from something as simple as a poorly connected antenna. This would move this crash squarely back into the "it was my fault" category


Terry - Sorry, I can't trade for building. I did this to get the 05G I have in it, and a 1/4 scale CAP 231 for a friend awaits my attention. I do have nice "books" about building them.......

I also saw tha fold out. I didn't buy the magazine though, as I already have all of the pictures in my own Tempest "library".



Ron

[Joel K. Scholz]

This sounds like a situation that has happened to me twice with the same airplane.I use this radio with other planes with no problems. This has ocurred near the end of a flight when thebatteries are probably getting low. I believe it is happening when the BEC shuts out, and because the bec rating is close to maxed out with the motor setup and I am using and with 9 cells. This allows the voltage drop at the batteries to drop so low at the time of engine cutout that there isn't enough voltage to move the servos. The plane momentarily goes out of control then regained in a moment or two. If you are using ten cells you and more than 2 servos you may be overtaxing your system. Check the ratinfg on your BEC . You may be using too many servos and cells.

[Ron Daniels]

Joel,

I think I eliminated the possibility that it was too many servos and too much volatage with my 2-packs-in-a-row, 1/3 throttle no cooling torture test. As I said, the ESC only got warm. No part of it was hot, and I had no problems.

When I lost radio contact with the plane, it was not far away, and flying straight and level (no servos draining current).

I was able to get glitches during range checks after the problem, even with the motor not running.

Since I lost a different airplane to a radio problem with a different receiver, motor set-up, cell and servo count, but using the same transmitter, I am strongly suspecting the transmitter at this time.


If it is OK, it will be a while, until I get this thing fixed and feel confident enough to fly anything on any of the equipment involved in either crash.


Ron

[AirJer]

Ron:

Nice Tempest.

One of the prettier warbirds.

Shame the camo works so well :-)

What is your all up weight without batteries?

Terry:

Get back to work!

Jerry Holcomb

[Ron Daniels]

I don't know off-hand what the empty weight is, but it comes to about 3 1/4 lbs, with 10 4/5 Sub-C's on board.

It feels light in the air at that weight.



Ron

[Ron Daniels]

The Tempest is flight worthy again (electrics don't need to be painted for test-flying...).

My 2400 CP cells are also in, so I may test-fly it with the big cells, using my other transmitter, before I re-paint it, weather permitting. And, if there is still light after I completed my very, very thorough range checks.........

I'm really looking forward to seeing how much duration I get with my set-up, and I don't want to wait.

It only took me about an hour of framing and about 15 minutes of covering to get it back to flight worthy. During this week, I'll finish painting my 1/8 Typhoon (I put a 1/4" plug in between the firewall and the cowling to avoid having to put in any ballast - 18 X 2400, Maxcim 13 y), re-paint my Ryan Hellcat (completing the repairs needed due to the other radio crash I had with this transmitter), and re-paint the left wing tip of the Tempest. All use the same colours, so the extra painting time needed to fix the Tempest will work out to a matter of minutes. Now, if only my old Mk V Tempest was re-finished and ready to paint.....


I'll post a picture of the damage, and the pre-paint repair some time during the week, when the film roll is developed.

I don't know how the plane managed to disintegrate the second-last rib, and cut out the d-tube and spar, and yet have the aileron and aileron spar keep the wing tip firmly attached, but I am very grateful it did. If it had sheared right through, the only good repair would have been to build and install a new outer wing panel for that side. It can be done fairly easily, and it is nice to be confident that all repaired parts are "good as new", but it requires re-covering and painting an entire wing half, and that's a lot more work than what I had to do.



Ron

[DaveW]

Hi,

I had some similar intermittant problems with a JR 652 transmitter last year. Would work fine for a while, sometimes weeks and then quit, sometimes for a moment, but twice crashed a plane.

The problem was a bad solder joint on the antenna connection. ( JR repair report )

I have since heard of 4 others with the same problem

Ground checks with antenna collapsed will not show this problem, it only occurs when the antenna is extended.

FYI

Dave

[Ken Lapointe]

Ron,
I was able to fly my Tempest MKII this weekend. Great flyer once I got the CG in the right place. I only tried the APC-E 11x8.5 with the Astro 05G on 10 2000 cells, but that worked great. Lots of thrust and speed. The plane really like to go fast. It did not seem to like to fly too slow for me , proably my flyng ability and not due to the plane. The plane lands great even without the landing gear.

I had a oh oh moment too. Advanced throttle, motor noise goes up. plane slows down and sinks, not looking good, very quick landing. Inspection shows a stripped pinion gear on the good ole Astroflight gearbox. That will get fixed this week.

All the club members love the plane too.

Great Job on the design

Ken

[Ron Daniels]

Hey Ken!

I'm glad that you were able to get safely back to the field when you lost motor power. Between the two of us, we don't seem to be taking full advantage of the "no deadstick" aspect of e-flight, these days.....

When I didn't get my power back up, I got almost to the field, and nearly over a tree.......



Considering the noise, we were expecting to need a shop vac to get this plane home. There was not so much as a dent anywhere else.

We had steady rain here today, so I'll have time to re-painting before I fly it again. I hope to eventually forget where the damage was.

My aileron trim will tell me if I got it alligned properly.

As for low speed flying...

At speeds approaching the stall, the Tempest should feel really mushy, but not twitchy. It will be a bit unsettling, as the nose will be quite high, and you will be holding a lot of elevator. While the Tempest is fairly safe to fly in this flight regime (I don't get too concerned unless I have more than 1/4" of elevator into it), it is not "in the groove" as it is at a bit higher speeds.

Take it up high and fly it slower and slower until you get it to stall (if your C/G and elvator throw can get it to stall). Unless there is too much elevator travel ( ~ 1/2"+), a rearward C/G, or a bad wing warp, you will find that there is a large difference in speed between where it starts to feel mushy, and when it finally stalls. Itf it stalls at less than 3/8" elevator, you are either tail heavy, or have a warp. If you have a warp, simply raise both ailerons a 16th or so at neutral, and this will mask the effects of a warp.


Really push the limits of your Tempest during these high altitude stall tests. This way, you'll know what your options are, if an emergency arises (Do I have enough speed left to turn?, How much farther will it glide? Can I pull up over this runway obsticle?, will it torque to the left if I grab a bunch of throttle at 3/4 elevator?).







Ron