|Oct 25, 2011, 01:06 AM|
|Oct 25, 2011, 07:57 AM|
Burdo is right. This WAS my T-45. I think I might have built it too big...
My plane only needs the power system and it's ready to go. Just got my ICE2 HV120 back from CC. However-- I don't know what I'm doing wrong. I tested three different 90mm fan systems on 6S, and got static thrust anywhere from 2.6lb to 4.5lb. This is not enough. I'm thinking about possibly getting another combination, maybe an 8S system. HET, WeMoTec, NEU, ARC, or something. Or I'm doing something wrong, and I need to figure it out. Some of you are flying this plane on the CS fan with the Warhead 1850kV motor. I got 3.6lb thrust on this system (no intakes or thrust tubes). I don't know...
|Oct 25, 2011, 11:05 AM|
About 5lbs + of thrust is what you expect at ca. 2000W ... below that I would be hesitant to fly this thing.
What motor do you have, and what kv ?
I find this calculator extremely useful, it will allow you to fine tune your setup.
If 6S does not do it, have you tried 7S (3S+4S)?
You can see what my setup is like by entering 8S 3000's, the Midifan, 80% FSA and the HET 700 kv=1485 motor.
You can substitute a Neu motor with similar kv and weight in the calc to ge a number ...
|Oct 25, 2011, 02:06 PM|
OK. Speaking with my friend (X30Pilot) and still considering the fact that I have plenty of 6S 5000mAh batteries, I just ordered the HET 9305v2 700 with the Typhoon 700-68-2250 motor. Note that I chose the 2250kV which was recommended for the 6S setup. It does look like I will be running "north" of 100A, but I'm going to use my recently returned CC Ice2 120HV ESC with it, so I have enough headroom. It looks like this setup should give me a good 2000W+ on 6S. I used the calculator and based on your numbers (as much as possible) got the attached. Does this make sense?
It shows a static thrust of some 5.2lb, better than the 4.5lb I got with the other fans I tried with. Let's say this--I will install this, get the intakes and thrust tube sealed to the fan, and take off. If it doesn't take off with this--I'm out of ideas...
|Oct 25, 2011, 06:49 PM|
Yes that would work, but if it was mine I would
a) maybe use a lighter motor, I am starting to think the -68 is an overkill, these
het 700 motors run as cool as ice.
I would have used the -60, kv=2085 ...
b) use a lighter battery, at least initially ... I would have used a 6S 4000 or
even 6S 3000 initially ...
c) The Arc in the WeMoTec Midi is also a good lightweight combo. The
Midi is better balanced than the new HET 90mm fan ...
The weight is critical on the (heavy) T-45, this thing comes out quite a bit heavier than say the Sapac T-45 70mm. And it feels a lot heavier.
|Oct 25, 2011, 09:49 PM|
OK, Herb, you had me check...
HET 9305v2-700: 76g
HET 700-68: 330g
HET 700-60: 280g
ARC 36-65-1: 300g
6S 5000: 770g
6S 4000: 623g
6S 3600: 577g
6S 3300: 489g
It seems that the WeMoTec fan with ARC motor weigh just about the same as the HET fan + 700-68 motor. Using the HET 700-60 motor would save 50g.
No doubt--the biggest difference is in the battery use. I have all the batteries above. Going from 5000mAh to 3300mAh would save 280g!
I do have 3300mAh (as 2x 3S), but I think they weigh a little more than the "native" 6S 3300mAh. However--I do have 4x 6S 3600mAh (Turnigy, 30-40C) batteries, which means they would provide 108A-144A. Should be enough for a couple of short flights. Now the question is if I start with those 3600mAh batteries on the first flights to get a slightly lighter plane (let's face it--the probability of recovering from the landing are probably less than 50%...), or go with the 5000mAh battery on the first flight, getting more air time of that flight, even though I increase the landing weight and reduce the probability of surviving the first landing...
|Oct 25, 2011, 11:32 PM|
Yes the first flight on 3000's or 4000's will be a bit shorter but all you will need is trim here out and get used to the flight characteristics.
You can use the heavier battery later.
108A x 21V = 2270W will be plenty for the first flight, esp. when you have less weight to carry - you will need less power.
|Oct 25, 2011, 11:57 PM|
From their respective web sites...
I'll make the first flights with the 3600s, then.
As soon as the power system arrives, I'll put it together (balance if needed), and go to maiden before the winter kicks in...
|Oct 26, 2011, 12:27 AM|
Well the HET 700 fan weight on their web page is clearly wrong ...
The Wemotec Midi weight on their web page includes the (big) intake ring !
Both weights below are the bare fan w/o heatsinks, lips etc.
|Oct 28, 2011, 06:33 PM|
United States, TN, Jackson
Joined Mar 2007
|Oct 30, 2011, 05:49 PM|
Joined May 2011
First Flight Report
Hi all, I carried out my first flight at the weekend and the report although brief is as follows:
Set up as follows:
2x 3S 4400 60C batteries
RC Lander 90mm fan
Hobbywing 120Amp ESC
Carbonfibre reinforced ducting
RCLander electric retracts
Wing fences fitted
Aileron reflex 2mm fixed
Wind light (5-8 knots)
Inital flight plan was to check control and balance of model. 2-3 circuits and then land. No flap or retracts will be used on the first flight.
The T-45 was allowed to gain excess speed on takeoff and rotated off with positive elevator (possibly due to forward CofG) plenty of acceleration with only 6S, takeoff roll from start to rotation 70 meters. Model had too much aileron movement which made roll control uncomfortable, will be reducing to 9/10mm each way as suggested in previous threads. The T-45 tracked straight and was very stable in pitch,there was no nose drop as power was reduced (ducting is pointing slight down).
2 wide circuits were carried out, not wanting pull to hard but even at 90 degree bank model tracked straight and true but ailerons were too sensitive for comfort.
Initial approach carried too much speed so an abort was called, the wing felt solid in pitch and the rate of decent could be controlled with throttle. On second and final approach model was slowed in the final turn and tracked straight but still felt uncomfortable in roll. The nose was held slightly up with no hint of a wing drop. The roundout was slightly too high causing a slightly bumpy landing and dislodging the noseleg mounts (pilot error not model design).
After the landing the batteries were checked (slightly warm after 3 minute flight mostly at 90-100 power) ESC cool-cold.
I have not had a chance to check how much power was used during the flight but will update later. Overall despite the knocking knees I felt very happy with the model and will be setting the model up for more tests. Thanks to everyone for their comments in previous threads, I just need to wait for the UK weather to settle down a bit more before future flights.
|Oct 30, 2011, 08:43 PM|
Had a few flights today. I weighed the jet today and it came out @ 7lbs even with a 6s 5000 pack. My last t-45 came in around 6 1/4lbs smfh
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