New EPP F-22 Grayson Powered is AWESOME!!!

[akent]

Well, this is F-22 number three!
I really wanted to try a faster one, like 19k's. My first Grayson powered one failed as I didn't make the elevon's strong enough. I scrapped that one.

This one flies great! It's also flying in the mid 60mph range, from several folks at the field today. It is way faster than the P-51, that's for sure, and way slower than the Stryker. I flew six batteries through it today! I love it!

I just need to tweak the CG some, as it does NOT do high alpha very well. It does like to go fast though! My old F-22 is the high alpha king. It is slow, but you can stop it and it will hover in a 5-10mph wind all day! Not the new fast one. It starts rocking and then tip stalls. I think I can make that better.
For some reason, this new one sure likes aft CG. I had it all the way back to slightly behind the motor mount! It still acted nose heavy with high alpha. Humm...

But the plane is rock stable at all speeds. Every time I fly these at the field, folks come over and comment on how well these fly. Many had no idea they were scratch foamies!

I might add some CF to the elevons after all, as in a full throttle dive from a few hundred feet up, it takes full throws to get it to level out! Either that or the servos aren't strong enough. These are HXT-900's.

Anyway, I am a happy camper today!
I flew:
1. New Grayson powered F-22 (six batteries)
2. Original F-22 (two batteries)
3. Delta dart (three batteries, flying with a fellow who had a slightly bigger one that he flies combat with! That was fun!)
4. Exi 500 (two batteries)
5. Yak-55 (one battery - too windy for this one)
6. Exi 450 (one battery)
7. F-27C Stryker (five batteries!!! Man is this one great!)

Zero crashes! What a day!









Sorry, I forgot my camera today. Those pics were from the build.
Kent

[akent]

Here's a few more pics from just now after a day of flying.

I wonder if the Parkzone props are any faster than this APC?

[Gabe]

Nice Kent!

Looks like good ol' trial and error is payin' off. Good looking scratch build, if I don't say so myself.

[19000rpm]

What a great day I think all you need to do is get your CG back a bit for better high alpha. sounds like your speed is about the same as mine was.

[akent]

Apr 19, 2010 5:29:13 GMT -6 19000rpm said:

What a great day I think all you need to do is get your CG back a bit for better high alpha. sounds like your speed is about the same as mine was.

It does sound like it. I have a hard time telling speed with these things. They look slower to me when I'm flying em.

But some ole timers at the field were the speed indicators!

The thing is awesome though, as it flies really slowly and then you can nail it and shoot for the moon rolling all the way up! I love that. This thing is actually nicer to watch doing that than the Stryker (with stock power).

The old F-22 just has no guts! It flies awesomely if you want high alpha, and it does have unlimited vertical, but it just doesn't have any guts!
This new one has POWER, and it screams doing it!

I am just really happy it flies as well as it does. I'll move stuff back, even if I have to glue some fishing weights back there, to get similar high alpha to the old one...
Kent

[fireguzzi]

Let me interrupt your thread with a newbie question if I may. (Like threads never get off track here right?) What do you mean by high alpha?

[19000rpm]

This isn't at all off topic since the plane being discussed is high alpha capable. Even if it wasn't on topic we wouldn't care.

High alpha is a term that describes a "high"- "angle of attack" (Angle of Attack=alpha) maneuvers.

Variations of high alpha maneuvers, that you may recognize, are the Russian developed "Cobra" and, to some extent, the "Harrier", named after the British plane of the same name used by the Marines.

It's a fun and sometimes challenging maneuver to achieve with many types of planes while others are designed to accomplish it with relative ease.

The best model aircraft to achieve high alpha with are high thrust to weight ratio planes. These include what is commonly referred to as "3D" or "F3P" designs and the pusher jets we're building.

Thrust Vectoring (being able to direct the motors thrust through a large range of angles) and gyros can have a huge positive affect on a high alpha planes capability. Got to RCPowers.com and look up the Sukhoi 37 thrust vectoring jet.

[akent]

Well said, 19k!

Hey Fire, high alpha is something that grows on you, too. I love to see how long I can basically hover the thing in a low wind! It is challenging, and with these foamies, who cares if you crash! They either sustain zero damage or you just get out some glue and you are back flying in no time!
Kent

[akent]

My new F-22 doesn't do Cubans as well as my original one, but they do resemble them if going slow.
(For everyone else, Cubans are kind of like heli flips. You turn on yourself, basically.)

I think I have a problem with flex at full throttle. It doesn't want to turn! At full throttle, it takes pretty much full ailerons to turn. Have you seen that, 19k? I did just add some CF to the elevons. I might add more... I just hope it's not the servo strength...

Here's a video from this afternoon!

[19000rpm]

High Alpha: There are a few things that make your Grayson different than your original F22. Weight, which affects the wing loading and CG. You can't alter the wing loading, so the CG is the only thing you can play with unless you go to a bigger prop which will likely help the HA, but slow it down too.

Without thrust vectoring the only other way to improve HA would be to have rudders to keep the nose straight, and the plane from falling off, in the yaw axis.

Turns: You need full elevon throw to get a decent turn. I think the CF in the elevons helps. The airframe is soft and all that flat, twisting foam is going to work against you in WOT maneuvers.

It doesn't look like your plane is much, if any, different than mine in overall performance. Maybe mine is doing a bit better in HA. Your turns and rolls look similar.

We've got to remember this is a compromise build; taking a light low powered HA plane and turning it into a fast plane. This plane has no airfoil. That really compromises high speed maneuvers along with the flexing foam.

[fireguzzi]

Ok I think I get the idea about high alpha.

[akent]

Apr 21, 2010 6:23:23 GMT -6 19000rpm said:

High Alpha: There are a few things that make your Grayson different than your original F22. Weight, which affects the wing loading and CG. You can't alter the wing loading, so the CG is the only thing you can play with unless you go to a bigger prop which will likely help the HA, but slow it down too.

Without thrust vectoring the only other way to improve HA would be to have rudders to keep the nose straight, and the plane from falling off, in the yaw axis.

Turns: You need full elevon throw to get a decent turn. I think the CF in the elevons helps. The airframe is soft and all that flat, twisting foam is going to work against you in WOT maneuvers.

It doesn't look like your plane is much, if any, different than mine in overall performance. Maybe mine is doing a bit better in HA. Your turns and rolls look similar.

We've got to remember this is a compromise build; taking a light low powered HA plane and turning it into a fast plane. This plane has no airfoil. That really compromises high speed maneuvers along with the flexing foam.

All really true, 19k!! I guess I just didn't expect that speed would actually make it really mushy!
The flying table I built as my first foamie became seriously unstable at speed. There was almost nothing you could do to control it, but it was made from fan fold (like Depron).

I didn't get a chance to fly this evening with the added CF. I'll keep adding stiffness until it flies well, and if it doesn't, I'll put on some stronger servos.

Humm, I have some full sized servos for my 600 heli laying around!!! I think they each weigh as much each as the whole F-22!

[19000rpm]

I don't think servos are an issue. At least they don't seem to be on mine. I'm using some cheap Blue Birds and they've survived two monster crashes and still seem to be up to the job.

If you get a really stiff airframe then I think the handling will improve. I'd like to build one like that. It's probably going to be considerably heavier though. An excuse to use the Grayson V3 motor.

[akent]

The V3, or maybe one of the Turnigy's that I'm running in the Stryker!!!
Heehee...

[19000rpm]

Apr 23, 2010 16:26:42 GMT -6 akent said:

The V3, or maybe one of the Turnigy's that I'm running in the Stryker!!!
Heehee...

I think the Turnigy would be way too much. But since it's your plane...Go for it. ;D