Hawker Tempest Mk II painted (finally)

[Ron Daniels]

This was ready to paint in February 2001. I finally painted it last week.

Work can really cut into your hobbies!

Hawker Tempest Mk II - direct predecessor to the Sea Fury






I had another Mk II a few years back, but I did it in silver. I think I like it much better in this scheme (actual scheme, serial and squadron code, circa 1947).


45.1" span, 367 sq in

Magnetic Mayhem, 3:1 (will experiment with 2.5:1, as well).

10 cells - I have 1000 SCR's on hand. I will fly it with them, and then decide between 1700CP's (same size and weight as 1000's) or 2400CP/SCRC. I'm leaning towards the 2400's. That way, I'll have a higher climb-rate shorter flight on one pack, and a more scale longer flight on the other pack.

4 channel



Ron Daniels

[Sligh]

Looks really good Ron. The Hawkers are one of my favorites.

[Airnut 2]

Very nice Ron, I will be interested in seeing the rest of your test results with the MM, 2.5-1 setup. How about performance on 8 2000SCR's?

[Marten]

What's your weight (well, the model's)?

[Ron Daniels]

My weight is best described as somewhere between adequate and substantial


The model was 333 g before covering, and about 450 after covering. I have not weighed it since painting, but I suspect that it is about 500-530 g empty, at this point. 454g = 1 lb

I anticipate a flying weight of about 2.6 lbs with CP 1300's, ~2.9 with CP 1700's (or my 1000 SCR's), or about 3 1/4 with 2400's.

I want a pitch speed of about 70 mph, and 28-32 oz of static thrust.

I figure a 10 x 8 at about 9000 RPM should satify both of these, without exhibiting the low speed/high throttle torque reaction that an 11 x 10 or 12 x 9 would exhibit. This is why I plan to experiment with the lower reduction ratio and smaller prop.

I'll give up a bit of propellor efficiency to avoid having to stand on rudder in extended low-speed climbs.

8 cells at 2.5:1 with a 12 X 8 or so should work, but may not have quite the duration, as you'll be drawing higher current.

I think 225-270 W output is about right for this model.


Ron Daniels

[knight of Ni]

8 cells should be enough. Our class of Newbies is using a trainer that uses a MM reverse with a 2.5:1 GP gearbox, and either 11x9, or 12x8 prop (11x 9 gives it good speed). Our AUW is a bit higher, but more wing area, so... About 6 min duration on 1600's this year we're going to use 2400's, so should be better in the climb

[dottney]

Nice looking plane!! Keep us informed on the progress. I have a SureFlight foam Spit that is a bout the same size waiting in the wings.
I didn't think you could use 10 with a MM.
Again let us know how things work.
Dave

[Ron Daniels]

I don't get the impression that the motors really care about voltage, directly.

I think you can run the motors at a wide range of voltages, provided that you keep the current within the specified range.

You may run into RPM issues, though, such as accelerated wear of bearings, or (in an extreme case) throwing the windings off from the G forces of very high RPM rotation.

Knight of Ni....What RPM do you get with the 11X9?


Ron Daniels

[Ron Daniels]

I did some testing of my two possible motors for this plane and my two M/A gearbox ratios, and this is what I came up with.


Trinity Speedworks 350 (17 turn, double wing, ball bearing, adjustible timing) ~ 218 g, with gearbox - I believe the "atomic force" motor or the 18 turn motor in that series will be similar.

7 cells

10X8 APC, 3:1 7300 rpm, 185 W, 55 mph, 20 oz thrust

10 cells

9X6 M/A, 2.5:1 8900 rpm, 146 W, 51 mph, 23 oz

10X8 APC, 2.5:1 7400 rpm, 144 W, 56 mph, 21 oz (suspect - was battery low?)

10X8 APC, 3.0:1 8200 rpm, 196 W, 62 mph, 25 oz

11X10 M/A 3.0:1 6900 rpm, 252 W, 65 mph, 31 oz



Magnetic Mayhem reverse wind ~ 240 g, with gearbox

7 cells

10X8 APC, 2.5:1 5900 rpm, 72 W, 44 mph, 13 oz

10 cells

11X10 M/A, 3.0:1 6000 rpm, 169 W, 57 mph, 24 oz

10X8 APC, 2.5:1 7750 rpm, 167 W, 59 mph, 23 oz

11X10 M/A, 2.5:1 6300 rpm, 184 W, 59 mph, 25 oz


All wattages are outputs at the prop.

As you can see, the closest match that I have to my needs is not the MM, but the Speedworks 350, at 3.0:1, 10 cells, 11 X 10 prop.


For thrust to weight ratio, this means

0.74:1 for 1300's, 0.67:1 for 1000 SCR (or Cp 1700's), and 0.60:1 for the 2400's. My current Tempest has a thrust to weight ratio of 0.52:1 and has climbs with great authority.

Now all I have to do is find out if my ESC will run the BEC for the whole flight on 10 cells. My Castle pegasus 35 does, and my GP 50 A electrifight didn't in another plane. Maybe with better cooling it will. I also have a Wattage 50 amp, that I will test for this.

Any comments or input is more than welcome.


Ron Daniels

[knight of Ni]

Don't know the RPM off the top of my head, DougB, you out there (little help! )

[DougB]

Hi Guys,

Mike FYI, the combo we use pushes about 6,300 RPM on an APCe 12 X 8 on 8 1800-2400's drawing about 23 amps. Don't know the exact speed but would expect it to be in the 40-45mph range with the Clark Y airfoil we're using. Hope this helps Ron...
DougB

[Ron Daniels]

Thanks, Guys.

I'll definitely need more pitch speed than 45 mph.


The Tempest that I fly right now has a max static pitch speed of 70 MPH, and has a very realistic flight envelope, in terms of crisp maneuvering and size of loops available from level.

I do like that 23 A current draw, though......

On the Speedworks 350 at 2.5:1, I think that I must have run it with the 7 cell pack, rather than the 10, or the 10 must have been practically dead. I know that this combo in a 50 flat bottomed airplane yanked it straight up, where the 7 cell gave good "scale" power.




Ron

[mrittinger]

Ron,
Good job, buddy!
I want you to do one in Reno colors, so I run against you at Mid Am next year with my Reno 51(I'm serious!)
You know well that I run the 3.5:1 MAS box, and the 12-10 APC off ten 1250 nicads or 2000 nimh cells.
I do NOT see any torque related problems at all.In fact, at slow speeds, the big prop throws so much air over the wing and tail surfaces I can almost walk the thing in.
The pitch speed is lower than what you are going for, at about 60-65 mph.Amp draw is around 22-24 .
The 2.5 box will give you more pitch speed, but it will be a bit hairier to get off ( at that weight) due to less static.Thats one of the reasons I went to the higher ratio, more stump pulling power at low speeds.I throw the things myself, no helper, and if it comes off a little crokked, it doesn't matter as the fan pulls it straight...
I initially tried a 2.5 box on my 50" version P51 after reading how Pat Tritle used it (Actually a 2.33 Belt Drive)on his Jug.But it didn't have it , not the way I liked anyway.
Give it a try though.I'm willing to bet your gonna end up where I'm at though.Or at least closer .
I LIKE haveing the big static numbers, gives good pull through the vertical.

Good Luck, keep us posted.See you in 5 more months!

Mark

[Ron Daniels]

Hi Mark!


Good to hear from you.

The Mk II won't be going in reno colours, but I do have to update my <I>Sea Fury</I> eventually. I've got a couple of projects between these (including a Mk V that I'll post a picture of here when I get the black painted on to the invasion stripes - retracts, bomb drops, and a very powerful *&^* engine).

When I do the Sea Fury again, it will be a serious, spare no expense speed machine. I'm going to do it in the colours of the full scale one on my web site. I was already talking about doing this on my way to the beach on July 9, the day after Ann Arbour, and the day that the Sea Fury crashed, killing Mr. Moore.

I like the colour scheme, and the cannons sticking out. I think I can find iron-on covering in close to the right colours, so I can give my airbrush a rest.



This is my cheap motor/endurance bird. I'm leaning towards 2400's to see if I can break the 10 minute mark, with a bit of civility on the throttle.

I've updated the photos here to better ones. As usual, it takes me 30 shots to get one that I like.


-Ron

[Ron Daniels]

I've now got this thing ready to fly.

With a Magnetic Mayhem with 2.5:1 M/A gearbox, 10 1000 SCR's, painted Solar Tex covering, and 4 channels with 2 aileron servos, the weight came out to 3.21 lbs, ready to fly. This is about 0.3 lbs above my earlier estimate.

When I dropped in the battery in the most convenient spot to check C/G, it was about 1/8 forward of where I usually put it - perfect for test-flying.

I decided on the MM when I blew up my GP 50 A ESC testing the other motor. Maybe it wasn't so efficient at those outputs

I may still grind a few grams out of the firewall to get more cooling air to my ESC (this plane started out intended as a glow powered combat plane, and has the heavier glow firewall in it).

Wing loading works out to 20.16 ounces per sq ft. This is a little bit lower than my old Tempest on CP 1300's.

I'd like a bit more static than the 25 ounces that I'm getting, but I suspect I'll see another 2-300 RPM now that I've properly wired in the MM (in earlier tests, the wiring was not soldered yet), and it's a bit more broken in. This should bring the numbers up a bit.

Mark R., if I wind up with a 12" prop, you do realize that I will have to admit you were right!

Now all I need to do is get some good weather (we got 4" of wet snow today), and I'm ready to test-fly.

If it's floaty and has good climb, I'll get some 2400's, if it is just right, I'll get some CP 1700's.


Ron