Methor

Alright all you Ultra Sport guru's. I have an original Ultra Sport 40 in kit form that i purchased a few years ago on ebay. I have finally finished building it!! it has been a long time coming. Anyways, it's setup is:

O.S. .46 AX
Futaba 7CHP radio
have futaba s2131 digital servos on all controls except throttle, futaba s148
2 aileron servos w/ flaperons
GP mech retracts
Monokote covering.

I guess that's about all the important items. However, after full setup, it comes in at 6 lbs even. I'm just wondering what a normal weight for this plane w/ a .46 engine and mech retracts is. I'm just worried it may be a little bit heavy and there might not be that great of vertical. I'm not looking for unlimited or anything, but would certainly like it to have decent vertical.

So to anyone out there with this airplane and similar setup...what is a good weight for this plane?
[img][/img]

camss69

My Feedback: (46)

I don't have that specific setup, but I had a GP extra 300s with a 46ax and I think it was right around 6lbs and it had very good vertical, not unlimited but definately good. I think you should be fine, fly it and if you don't like it then worry about it..

MinnFlyer

My Feedback: (4)

I don't recall what mine weighed, but I think you will be very happy!

In fact, on my original US, I fully sheeted the top and bottom of the wing

Second one sheeted just the top.

So they were both on the heavy side

jrf

My Feedback: (551)

6 pounds is about right. Your vertical will be very good, but it would be a lot better with an APC 11x5 prop.

Jim

britbrat

6 lbs is pretty much right on the nose for it. Don't worry about vertical performance -- it will have plenty (horizontal too!!).

LSP972

My Feedback: (13)

VERY nice covering job, dude.

I expect RCKen is drooling right about now...

RCKen

My Feedback: (9)

britbrat

Took yer breath away huh? (the "huh" bit was me pretending to be a yank -- I would really have said "Eh?")

Methor

for those who are wondering or happen to stumble upon this thread, i have flown this airplane several times and right now with a 11x7 master airscrew prop, she climbs to almost out of sight after a high speed pass, and i'm guessing flying in the 100 mph range. so as far as the weight is concerned, it seems to be a good weight for this plane.

Jäegermeister

britbrat

I think that you're off a fair bit in your speed estimate -- I would say 85 MPH is a better bet on the level.

MinnFlyer

My Feedback: (4)

I don't think 100 mph is unreasonable. I had my Skybolt clocked at 89mph, and my US 40 is considerably faster.

jrf

My Feedback: (551)

Static rpm times prop pitch is a very good estimate of level flight airspeed. An 11x7 would have to turn 14,300 on the ground to bring the airspeed up to 100. Not impossible, but unlikely. 12,000 will get you 85.

But why quibble? Either way it's dam* fast.

Jim

Methor

Well like i said i was guessing on the speed. I was just going by what some of the old guys at the field were telling me. unfortunately i don't have a tach yet...but i will definately check it's rpm when i get one...then i can better estimate how fast it goes in flight

All i know is it is fast!!!

Jäegermeister

Not24

My Feedback: (1)

Who are you calling old! I have a tach you can borrow. Get an apc 10-7 and a 10-8 for that engine and let her rip. Going to a 9" prop will cause you to lose thrust. If your engine is broken in good it should really turn up with a 10-7.

Dial some expo in that thing to smooth things out a bit. At that speed it's hard to be really smooth without a little help from the radio. I'd suggest -30% for starters. Good luck!

Methor

after reading your post again, i realized that you may be erraneous in your reasoning. I mean a trainer with the same engine and prop will NOT come close to 100 mph no matter what tach it is spinning at. so aerodynamics of the plane and design have much to do with the top speed.

Jäegermeister

MinnFlyer

My Feedback: (4)

Keep something else in mind...

When a 10x7 prop is tached on the ground it is pulling a lot of air through it, so it may tach at 12,000 or so. But move that plane through the air, and the prop has much less work to do, so RPM can go up considerably

jrf

My Feedback: (551)

The actual calculation of airspeed requires the assumption of values for drag, unloaded rpm and propeller efficiency. These values are not really subject to close estimation. ANY calculation of airspeed is going to be an estimate at best.

Over years of testing with radar guns, a number of detail oriented modelers have come to the conclusion that, for the average sport monoplane (like an Ultra Sport) static rpm divided by 1000, times pitch is a good estimate of level flight, steady state, maximum airspeed. Obviously, this would not be true for very draggy airframes or for very high pitch props (which tend to unload more in the air).

Jim

SLFlt

My Feedback: (1)

Methor,

Wow. Nice covering job. I too have an Ultra Sport. (Plain 'ol ARF) I put a Rossi .45 on it and it sounds cool. Currently I'm having some tuning problems but should be flying soon. I used the fixed gear as I didn't have the time for retracts. 6 pounds sounds about right. Wish me well on my maiden flight this week...!

-SLFlt

Methor

I almost bought an ARF version off ebay a few years ago...went for same price as Kit that i bought, but i realized how much plastic was included with the arfs made by GP and decided to stick with the kit. took a while to build, but I know how it is built, and i know the quality is up to my standards. I made sure of it . Plus, the wood seems easier to repair than the plastic. I have a spectrum ARF that the engine died just about midfield downwind about 30' off ground, went in nose first over some trees. that was about 2.5 years ago, still haven't tried to fix it. I believe it is repairable, but don't know long it will take or if i will need to try and find some new plastic parts. was only second flight too . it was kinda my fault too, cause the muffler came apart. With the ultra sport, i make sure EVERYTHING is in perfect working order and tight before flying it. anotehr plus for the kit planes. when you build them, you're more careful to not kill it .

Jäegermeister

MinnFlyer

My Feedback: (4)

Yea, the original Ultras Sport ARF was one of them "Old Style" ARF's

I wouldn't be at all surprised to see GP come out with a new all-wood version in the next few years.

I still say it's the best airplane ever!

airborn900

My Feedback: (25)

100Mph is not unlikely, I had a caviler 40 with a ST45 clocked on radar at 132. the OS46 is a much more powerful engine. I am starting a ultra sport kit this week, will let you know what it radars out at.

buzzingb

My Feedback: (2)

I flew a Ultra Sport+ a while back with an os 61, Saito 91 and with those engines you won't have to worry about vertical or speed. The Plus version doesn't mind the extra weight either as it flew light and stable. I think I would give the Tower 75 a try if I had it to do over.

Razor-RCU

My Feedback: (50)

BEAUTIFUL US-40!

I really enjoyed mine then I sold it for way too cheap...

Mine had an Irvine-53 and was fairly fast (Kinda ugly scheme though-)--- I avoid guessing on speed since it seems difficult to judge but if you guys are hitting 100 with a US-40 and 46FX or similar engine than my Jett-50 powered Patriot is at 150

Rod Bender

I have one of the old arfs with a Super Tigre G51 on it.... Very fast, fun plane...Greg

buzzingb

My Feedback: (2)

Just a follow up on the Tower 75 engine. I did try it and it is a great engine for the Ultra Sport It will pull a 12.5X6 very well. Much better than the OS 61FX. It however isn't a Jett and needs to get its power from lower rpms as torque.