Hi Everyone,

I am trying to figure out if my Hot Spot has the proper angle of attack while sitting on the ground. I'm using the Robart struts with BVM F-86 wheels an brakes. I put my wing incidence meter on the root yesterday and it read +3*. Would it be safe to raise the nose to +5.5*? I'm am trying to achive easier lift offs and shorter ground runs.

With the current +3* my Spot takes about 400' to get airborn with a RAM 1000R for power at 120,000 RPM (21 lbs of thrust). It weights 28lbs wet with 110 oz of fuel. My C.G. is at the rear recomend setting (Bob Wilcox instructions).

Is it a good idea to change the angle of attack or am I possibly getting myself into trouble?

Thanks,

Come on guys! I know there are a ton of Hot Spots out there and it wouldn't be real hard to slap your meter on it and see what you get. I guess I'll try it and hopefully it works.

Cheers,



FLY RAM

I do not forsee that it would be a problem, it'll just look funny sitting here and you won't be able to hold the nose up as far down the runway (paved) on smooth rollouts.

I've been flying HS for 2 years. Never bothered to measure. I have Robarts with Glennis 3" mains and 2 1/2" nose(2 3/4" will also fit the Robart lower strut). This gives slight nose up incidence.

I fly off grass most of the time, and the nose gets a bouncing during takeoff quite early and increases the incidence. I can pull it off grass in 150 at most. I am using a P-120 at max thrust with a speed limiter.

On asphalt, it takes about 200 feet max, but decreases to no more than 125-150 if I hold the brakes, and yank it off slow.
At FJ 2001, Torrey Ward took the challenge of a Bandit getting off quick. Torrey would go full throttle on his P-120 with brakes on, let loose when they started to slip, and yank it off in no more than 100 ft., pulling up to about 85 degree upline.

I would recommend getting a speed limiter and letting that RAM 1000 sing at max power.

Only problem you might see with 5+ degrees incidence is on windy days, when you want that nose down to kill all the lift of the wing as soon as possible. So it will be a tradeoff.

By the way, my plane is set up identical to Bob Wilcox's plane that Jason flies with a P-80.

One difference I notice is that you carry 105 oz fuel, all in front of the CG of course, whereas I have the GWM/JetCat USA 2500cc or about 83-84 oz. That is almost 1.50 lbs more fuel in front of the CG for takeoff than I use or Wilcox uses. That would slow down rotation quite a bit. It does take a while for those short-coupled elevons to really get a bite, even with full up during the early part of the Takeoff roll.

I still get 6-7 minute agressive flights, with enough fuel for 2-3 go arounds if necessay with the 2500 cc tank.

Tom

Hi Tom,

Thanks for you input on my sistuation. I have my RAM 1000 spinning at max RPM for my altitude. I fly at 4,600' MSL so if I push it any harder I start to get compressor stalls. It gets worse in the summer when it's 95* and density altitude climbs upwards of 9,000'. What's your field elevation?

I get some flights on the spot with the new mods and let you know how it gos. By the way, I have a speed limiter already.

Ooops! Forgot about your density altitude out there in SLC.

Only reason I mentioned the limiter was to keep it legal if in fact you were over 0.9 T/W installed.

My field altitude here is only 800MSL. Once in a while in the summer the DA gets up to 2000 tops. I fly a full scale Bonanza, often near gross weight, so I pay attention to DenAlt.

I think at your DA out there, that rather long T.O. run may be something you have to put up with. Like I noted before, it takes a bit more of a run, than say a Bandit with flaps. Those elevons are short coupled, with a small moment arm. That, along with the fuel you are carrying, probably accounts for your problem.

Just be careful with getting the nose too high in the static position. I have had a couple of x-wind landings, carrying a bit too much power, where the nose hits, and then boings back up hard, into almost a cobra maneuver. You like to get the nose as low as you can to unload the wing lift.

Good luck with your flights---let me know how things go. I love those Spots.

Tom

A10 flyer,

I would caution against setting up your HotSpot any more nose high on the ground.

I fly mine off hard rolled grass with a 17lb thrust JetCat P-80. I set the brakes, run the engine up to full throttle and release brakes when they start to slip. I'm off in about 250 feet. My HotSpot has the same setup as yours, Robart gear with the BVM wheels and brakes. It gets light real fast on takeoff roll and almost bounces into the air. HotSpots have gobs of lift, they will fly incredibly slow and will lift off at very low speed. I sure as heck would not want mine any more nose high on the ground as it would fly itself right off, possibly too soon. The other problem is landing, when you touch down you need to drop the nose immediately or risk bouncing back up, like I said it takes very little speed to get a Spot back into the air. You want that thing level on the ground to cut your lift to zero on rollout.

With all that power on your HotSpot it should be off in about 150 feet. Do you set your brakes and run up to full power first? That may explain why it takes so long for your HotSpot to get off the ground. If I just gave my JetCat full throttle and waited for the jet to accelerate the thing would be half-way into the next county before I got off the ground. With that RAM 1000 your HotSpot should blast off like a rocket.

Have you considered carrying less fuel? I carry 80 oz (2.5 litre), fly 4 or 5 minutes and land with 1/4 to 1/3 tank. You are carrying around 6 pounds of fuel. Try flying with 3/4 tank and run up to full power with the brakes set, I'll bet you get much better takeoff performance.