Tempest Mk II Test Flight

[Ron Daniels]

It was just too beuatiful an evening not to fly, so I test flew my Tempest Mk II tonight.

Mag Mayhem 2.5: 1, 10 X 1000 SCR cells, Wattage IC 550 ESC.

Tempest just pulled along at about 20º climb (angle of release) after launch, accelerating nicely. I stalled it by pulling too vertical while turning, and trying to climb over the sun on the climb out. It fell gently to the left, and lost about 15' before having full flying speed again.

1 click of down, 2 clicks of right aileron and 1 click of right rudder were needed. All about what I expected with that size of prop. C/G was set about 1/8' aft of recommended point, and felt perfect to me.

Aileron and elevator response was crisp and precise, with rudder being a touch mushy, as it tends ot be on Tempests.

I did a fast roll, a slow roll and various turns. All felt solid and predictable.

The speed was not overwhelming with the MM, but it sounded quite nice at about 1/3 throttle, when enough load was on the prop to silence the typical M/A gearbox "chirping".

I found duration to be longer than I expected based on my ground tests. This is because I throttled back to 1/3 for a really solid cruise, rather than about 1/2 as I do with my old E-Tempest. I found that the new (larger) Tempest will fly noticably slower than the old one before the handling starts to lose its crispness.

I flew it for a bit over 3 minutes before bringing it in.

For landing, I brought it in shallow, crossing the threshold at about 4'. I chopped to idle about 20 yd short of the threshold, and pulled the trim back to nothing right at the threshold.

I came in on a bit of an angle, so I touched a bit or rudder to line it up, and then started feeding elevator. I was at full elevator for about 20' when it settled in with the nose about 4" above the tail.

Unfortunately, the prop was still windmilling when it landed, and I broke a blade, as well as bending the prop shaft on the gearbox. Too bad - I was going to do a second flight with my lighter 10 X 1300 CP pack from my older Tempest.

All in all, I think the handling was superior to my older Tempest, due to the lower speeds at which the plane will fly before it gets mushy. Cruising at 1/3 throttle produces a very scale-like flight, with some pretty neat brbrbrbrbrrrr sounds coming off of the prop.

I think that the MM, 2.5:1, and 10 CP 1700's (same size and weight as my 1000 SCR's) is a great combination for this plane, if you're looking for 6-7 minute scale like flights, and don't want to spend a lot.

I, on the other hand want a bit more top speed , and longer duration yet, for my "Ann Arbour Airwars" so I will re-motor mine with a brushed cobalt, and upsize the cells to 2400's.

With how "light on its feet" the Tempest felt to me with the 3/4 sub C's on board, I won't mind the extra weight at all.

I will also add a sub-micro servo to my throttle so that it pushes some nyrod out from behind the radial engine to stop the prop horizontally. I like wooden props.......




Ron

[mrittinger]

Sounds great to me!
I'll chase you around with the P40,or maybe the Ki61 when I get it done.
Sounds like your happy with the combo.I have never bent a shaft on the MAS boxes.They tend to strip out the driven gear instead.The best props in this setup , for me, tend to be the APC E props.Significantly more "Pull" than the wood MAS props for some reason.
I would order a few sets of gears from MAS website.I think the drivens are only $6.50 US...
I would still suggest trying the 3.5 ratio/12-10 setup someday.It has worked well.I think we can compare at Mid Am next year.
All in all, it sounds to me that your happy

Mark

[Ron Daniels]

Mark,

I'm going to stick a servo in my cowling, and have a piece of antenna sheath move out to interfere with the prop, either at idle, or via the retract channel (haven't decided which yet).

The idea is that the wind will freewheel the prop against this stop so that it always stops horizontally, thus saving having to wear an "ammo belt" of spare props to the flying field.

I was thinking for the Jug, you could do the same thing, but for the P-51, you could hide it in the exhaust stubs, and slide it out to the prop from there when landing.

Servo will pay for itself pretty quick if you like the pricey props like you and I do.

I got my hands on a gently used Astro 05 G last night, in a classic "will build for e-supplies" swap with a flying buddy.

We'll see if that gives me the speed/duration combo that I want.....





Ron

[Ken Lapointe]

Ron,
Glad to hear of the great flight.

I am still waiting for the wind to die down here to fly my Tempest. It's been steady at 10 - 20 with gusts to 30 for the last 2 weeks, well it seems like that anyway. Maybe that is why this area is so well loved by the big sailboat crowd.

Maybe this weekend I'll get out and give it a try.

Ken

[Ron Daniels]

Hi Ken,

I'm going to wind up with the same power system as you almost exactly.

I'm going to an Astro 05 G and 10 2400 CP cells.

If we share data, we'll be able to get the "perfect" prop for this model pretty quickly.

It looks like we'll also be really close in AUW.

I look forward to hearing about your flight.

From testing mine with a 60 MPH pitch speed, you'll do fine with a 59 MPH one.




Have Fun!

[Steven Horney]

Ron,

I've had great success with the Astro 05 geared and 10 cells using APC 10x8, 11x8, and 10x10 props. The 10x10 works best on something sleek, like an E-Streak; othewise, the 11x8 has generally been my prop of choice. These are the regular APC props, by the way. The only downside is that they are probably the strongest thing on your plane, and you can easily bend gearbox shafts if you hit hard/wrong with the prop down.

Steve

[Ron Daniels]

Thanks Steve!

I may try an 11 X 10, and if it lugs too much, trim it back to a 10 1/2 X 10. I have a feeling with the 10 X 10 in this application, I may be down a bit on static thrust. I know the 10 X 8 on the Astro 035 g would work very well (~ 8500 RPM).

I have a MaxCim 13 Y in my 1/8 Typhoon right now, and it is very tempting to run it direct in the Tempest on about 8 cells with a 10 X 6 or so (KV = 1450 RPM/V), but the guy I borrowed it from would have my hide......

I'm definitely going to put some sort of hard brake on the cowl to avoid having prop strikes on landing.



Have you decided how you are going to power your review Tempest yet?



Ron

[Ken Lapointe]

On my skyvolt, with the Astro 05G and 10 cells the best prop I have tried is the 11x8.5 APC-E. The plane has lots of thrust and plenty of speed. That will be my test prop for the Tempest MK II.


Wind for cast for Saturday is winds 13 mph with gusts to 28. I can hope it doesn't start before I can get in a flight or 2


Ken

[Steven Horney]

Hi Ron,

I'm planning to power my Tempest with a Jeti Phasor 30/3 direct drive on 10 cells and an APC 9x7 prop. I may also play with the geared Astro 035, and maybe a Jeti 15/4 or 15/3 on 8 cells (to see how it performs with a lower wing loading).

I think you'll find an 11x10 is too much prop for the geared 05 (standard gearbox) on 10 cells (but I'll be interested to hear your results if you try it). The 11x8 really pulls well - a good combination of thrust and speed. Current draw usually runs around 33 amps. The 10x10 has a similar current draw, but really works well on a sleek plane. On planes with a little more drag the 11x8 outperforms it.

Steve

[Ron Daniels]

Thanks for the info Steve.

Do you know what RPM you get with the 10X10. If it equates to 30 oz thrust on the Aveox virtual test stand, I'll probably try it out, rather than risk pushing the 05 beyond its limits.

Otherwise, an 11 X10 APC e-prop (if they make one) may work quite well, with a bit less current draw than a glow 11 X10.



Ron

[Ken Lapointe]

My Tempest had her first flight today. It was a bit brezzy but I got tired of waiting for better weather. Astro 05G, 10 2000 cells and an 11x8.5 APC-E. Was a bit shakey at first, I had to put in a bunch of down trim. Luckly the power just made it climb and climb it did. I have to check the CG again. I think I had it too far back and it clearly needs to go forward. Once I got the trim set to force the nose down it flew well. Handeled the breez fine. It is one fast plane on this set up. It had plenty of climb and speed. A couple of the glow flyers in the club even mentioned how fast it was

First landing was nice and smooth, even with the aft CG. Even the prop survied with no landing gear.

The battery box I built did not hold the battery well enough. It got a slight design change today to brace the box a bit better.

Once I get the CG in the right space this plane looks to be a real winner.

Only thing I would change if I were to build it again is to make a top hatch for the battery. I will probably make a hatch on this one if it survives the summer. Hey I never said I was a great pilot

Great Job Ron.

Ken

[Ron Daniels]

Ken,

Congratulations on your successful test-flight! I was thinking of contacting you and suggesting that if the wind wasn't snapping the flags, the main effect would just be an easier hand launch.

It sounds like the 8.5 E- prop is a pretty good match. I'll have to get me some of those.

I'm glad that the glow fliers were impressed with the speed. Sounds like it's time to put on some racing numbers!

The downside of having 10 2400's on board is that hte boattery box has to be twice as strong as for 10 800 AR's.

The upside is..... How was your duration? Was it about what I projected? I imagine that between the wind and the aft C/G you carried a bit more throttle than usual, so I expect it to increase under more favourable conditions, but I'd be interested to know, as I have to wait a week before my 2400's and 05G can be installed.

As for C/G, the recommended point will produce a slight tendency to balloon upwards when diving at 45º and full throttle.

I check my C/G by holding the plane upside down with my left and right index finger on with front wing sheeting at about the dihedral break. I place them at about 3/8 to 5/8 forward of the back of the spar, and look for the fuselage to be level or very slightly nose-down. It will still be flyable with C/G 3/4" aft of plans, but elevator response is a bit much

If your C/G is right based on this test, you may want to check your thrust line (should be ±0º WRT stab). If the airplane requires more than slight back pressure to hold level when you go from full to 1/3 throttle, and the C/G is correct from above, some upthrust may be present. Even 1-2º will be noticable.

I can't wait for my new motor/pack to get in now!!!!!


Ron