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electric mike
08-07-2005, 10:33 PM
My Aventura III (Twin Aventura), 2 x speed 400 powered seaplane, gunther-props with Jeti 45A ESC suffers from ESC overheating after a few minutes.

The fuselage being a closed space due to prohibiting water entering the fuselage seems to be a problem, thus the lack of fresh air cooling for the ESC seem to cause the ESC overheating.

Anybody out there who succeded in making air inlets and outlets to enhance ESC cooling, unaffected by water splashing during takeoff run?

BTW it's powered by an E-TEC 3s2p 1200mAh=2400 mAh, 11,1v LiPo ack and in order not to fry the motors I have limited the throttle travel to about 22 Amps max and about 200 watts according to my Astro Watt Meter.

/best regards - Mike in Sweden :cool:

donjiskra
08-08-2005, 08:09 PM
Hi Mike,
The Aventura Twin is a wonderful floart plane, isn't it!!!!

I question the use of a 3s li-po pack with those motors.
I burned out mine that way because they could not handle the 11.1 volts, and I suspect that is why your ESC is overheating also.

When I ran the motors on a 7 cell NiCd pack everything was really cool and the ESC never got that hot.

Perhaps going to a 2s pack would solve your problems????

Let me know your thoughts, OK?

I'd love to get a single motor version Aventura and install a brushless motor, using a 3s2p pack. I think it would really be a winner!!!

Hope this helps?
Don
USA

electric mike
08-08-2005, 10:06 PM
Tnx Don for your reply.

Yes, I think You are right about the 3s LiPos.
I will try a 2s LiPo pack instead. It is probably the 3s LiPos that is causing the ESC overheating problems, and the ESC running on half throttle or less all the time.

I will also change the 7,2v 400 motors to 6v 400's in order to perform better on a 2S LiPo pack.

A friend of mine, Fredrik W, went for a more expensive solution with his Twin Aventura, two AXI 2208/20 brushless outrunners, APC-SF 7x4" and one 3s1p Kokam 1500 LiPo per motor....and of course two separate Jeti brushless controllers.He got ballistic performance, takeoff run on water is 2 metres, which is approximately 2 yards...but he suffered the classic Aventura wing joining dowel failure, and cooked both his brushless controllers when the wing folded during heavy wind conditions and he crashed into the sea. His Aventura will be repaired, no other damage than to the centre section of the wing.

There is a construction/manufacturing snag with the Aventura.
The wing centre section (at least on some of the produced Aventuras) are made of far to soft solid balsa, and in combination with a very soft balsa wing spar, the wing will fold during a loop, or as in Fredrik's case, just normal flying but in heavy wind conditions.

I have now inspected the strenght of my own wing, and my wing spar that is visible thru the wing covering, seem to be made of harder balsa than Fredrik's wing spar. However I added five 10 inch long strips of glass fibre tape to the underside of my wing, in order to prevent any future problems with wing folding. Whatever it will do, I'm sure it now will not fold during heay loads.

I would recommend that you, if you haven't done so already, inspect the wing spar on your Aventura, and then maybe add some strength to the wing.

Have a nice day Don - best regards from Mike in Sweden

donjiskra
08-08-2005, 10:27 PM
Great reply, much appreciated!!!!
I'm impressed with Fredrik's "upgrading" and performance, AWESOME, but it teaches us many things, especially to consider the ramifications and consequence of what increased stresses will result. Please thank Fredrik for bringing out this weakness. I suspect the original designers never imagined a Swedish hotshot would excel their design. I'm thankful to him for his role in structural design testing!!!!
I'll check and make the necessary strengthening modifications.
God luck with your modifications also.
Let me know the results,
Don

electric mike
08-08-2005, 11:04 PM
Hello Don

In order to be able to test fly my Twin Aventura modifications on my flyings clubs grass field I have added a remove wheels undercarriage according to the Aventura plans. It has a two wheel main gear with a tail wheel.
Note that the manufacturers stated location of the wheels axis is wrong, they state 30 mm in front of the step on the fuselage. That will probably be at or behind the COG, which is not a good idea for a taildragger.
I mounted the cross-fuselage copper tube about 65 mm in front of the step, at which the Aventura seem to behave normally on wheels, but had to do a Z-bend leg to get the wheels about 50 mm below the cross-fuselage copper tube glued through the fuselage, parallel to the wing, otherwise the bottom of the fuselage will prevent the wheels touching the ground. Pictures will follow tomorrow.

BTW, my friend Fredrik has his own web site, www.flyingmodels.org (http://www.flyingmodels.org) which amongst other things also contain the Great Electric Motor Test with unbelievable lots of motors, cells and prop combinations.
Each motor (mostly brushless motors) is tested with 25 to 30 different props, and each prop with several different cell counts.

I would humbly advise a visit to his site, if you ever want independent performance data for mostly european motors, such as the AXI's, MEGA, MP-JET, Nippy, Plettenberg, Hacker, Jeti and Kontronik.

Have a nice day Don!

/best regards from Mike

http://eflight.hedlunds.net

Thayer
08-09-2005, 03:09 AM
2 x S-400 seaplane, ESC overheating after a few minutes.
The fuselage is a closed space
E-TEC 3s2p 2400 mAh, 11,1v LiPo pack
in order not to fry the motors I have limited the throttle travel to about 22 Amps max and about 200 watts according to my Astro Watt Meter.



Mike,

Not to put too fine a point on it, this sounds like a recipie for disappointment.

Limiting the throttle seems like a good idea, though in pratice doesn't work. The ESC and motor are still seeing the full power of the battery, though switched on and off at high rates. The Astro, and all other similar meters, only see the average current draw. This number will vary depending on the ratio of on/off duty cycles from the ESC.

Regardless of the stick position, You are overdriving ESC and motors. I recommend dropping back to a 2S pack, and expect all heating issues will go away.

100 watts into a S-400 motor is also at, if not beyond, the upper limit most people will run them at for sport flying. Dropping back to 75 watts will greatly improve longevity. Loosing a motor in a single isn't a big deal if it can glide at all. Loosing a motor in a twin can get too exciting too quickly.

Thayer

electric mike
08-09-2005, 09:34 AM
Thayer, you are absolutely right!

I will change to a 2s LiPo pack, and change the motors to 6v 400's, thus feeding the 6v motors 7,4 volts instead of feeding the 7,2 volts motors with 11,1 v.
Maybe I won't have to install cooling air inlets/outlets after all :)

Yes, loosing one motor in a twin can quickly cause very interesting flight patterns, which I don't want to experience personally, being a very un-adventurous person...

Tnx for the advice, I've just ordered the 2s2p 1800mAh =3600 mAh LiPo pack which hopefully will give me very long endurance.

Due to light weight LiPo pack and the Aventuras rather short nose,
I'm on the edge of having COG problems, since the 3s 2400 mAh LiPo pack, weigh only 165 grams=5,8 ounces, as far forward mounted as possible, gives me a COG 4 millimeters=1/5 inch rearwards position, therefore I now step up to a 3600 mAh 2 s pack weight 180 grams=6,4 ounces hoping to move the COG a millimeter or two forward.

/Have a nice day Thayer, and tnx from Mike in Sweden :)

donjiskra
08-09-2005, 01:26 PM
Hi Mike,
You are certainly getting good advice and it's encouraging to see the response. Will be looking forward to your results.
Yes indeed, Fredrik does have a great website and he is highly respected by me. I've shared comments with him previously and appreciate all he has/is doing to share his testing results and the website. A GOOD MAN!!!
I also installed wheels on my Aventura, but exactly as the plans indicated, except I did not install the tail wheel, since I have a grass field and it was not a problem. Take off were fine, but I had to use larger wheels due to the height of the grass and uneven ground.
Regarding the CG and li-po battery position:
I epoxied a 1 1/2" plywood strip to the bottom, the v of the bottom allows me to use a velvro tie-wrap to secure the battery for extra holding, even though the plywood strip has velcro for the battery.
Positioning of the li-po was simple and the CG location was easy to determine. The 3s Li-po pack saved 8 ounces, a huge saving!!!!
Here's a shot of my Aventura with wheels.
Happy flying,
don

electric mike
08-09-2005, 04:15 PM
Nice Aventura Don!

What motors are you using, they seem to have grown out of the cowl??
Brushless? And the props? 7 or 8 inches?

You didn't experience any problems with the wheels so close to the COG?
Perhaps by a coincidence, when I got the kit I made a plywood strip, identical to your description, also with velcro glued on top but also with a loose velcro strip underneath the ply strip, going around the ply strip and the battery for extra safety. No in-flight moving batteries here....!!

A pic of my Aventura with the custom forward moved landing gear, using two rubber bands, at the link below:

http://eflight.hedlunds.net/bilder/twin-aventura/aventura.jpg

Happy flying Don - best regards- Mike

donjiskra
08-09-2005, 10:36 PM
Mike,
I used Graupner Speed 480 #6304 7.2 v motors, using APC-E 6x4 props with metal spinners back plate and black plastic cones.
I know that the motor voltage is low for the 3s 11.1 li-po battery but I use a 35 amp ESC and only use initial full throttle for lift off, then I back off to 50 per cent. So far this has worked out fine.
I used a brass tube for the one piece wheel axle, when I go float flying this is all removed and then the two holes are silicon sealed.
The position of the CG did not change with the wheels installed as indicated on the plans.
The motors do not stick out in front of the cowls, what you see are the spinner plates.
Here's an E-calc program screen capture that show the awesome performance.
Don

Aerowhatt
08-14-2005, 11:17 PM
The easiest, best solution to the overheating ESC is to re prop the system so that you can use full throttle throws.

Gunthers on 7.2V 400's at 11.1V is significantly over propped. I have a couple of planes set up with 6V 400's and 11.1v Li-polys. They work fine if you choose the right prop. Both of mine run well with the GWS 5 X 4.3 direct drive props they are clean fast planes compared to the Adventura.

These props should solve your problem by letting you use full throttle throws on your 7.2V 400's without over amping them in flight. They will also give you better take off and vertical flight thrust, equal straight and level performance, While at the same time extending your flight durration by 10% to 20%.

When overvolting motors it's critical to prop for lower amps and more rpms. The 7.2V 400's can handle the higher rpms but not higher amperages.

It's a good idea to prop to the airframe too. Propping for a top speed of more than 2 times the neutral glide speed of an airframe starts using alot of power to overcome drag, pushing inflight amps way, way up.

Sticking with 11.1V - 7.2V 400's with the right props will give you greater versatility than dropping down a cell and changing the motors out to 6V. Not to mention the cost and work savings.

Aerowhatt

donjiskra
08-15-2005, 04:42 PM
are very informative and worthwhile. It's great to be able to use this forum to find solutions, much appreciated!!!

Your statement:"I have a couple of planes set up with 6V 400's and 11.1v Li-polys. They work fine if you choose the right prop. Both of mine run well with the GWS 5 X 4.3 direct drive props they are clean fast planes compared to the Adventura."

Intrigues me, what planes are you refering to?

Thanks,
Don

electric mike
08-15-2005, 06:17 PM
Did a comparative measurement of Amps at full throttle, having changed back to 8 round Nicad cells, and discovered that my two 7,2v MIG 400's with Günther-props used 36-38 Amps at full trottle and approximately 9 volts. This divides into 18-19A for a single 400 motor!
Changed to APC-E 6x4 props, and the current was about the same! On 8 round cells!

Conclusion: the MIG 400's I use must be a VERY hot wind, and are probably not representative as generic 400 motors.

I will try the GWS 5x4,3 props on 3S Lipos later this week, since I live in northern Sweden, and electric flight supplies has to travel 621 miles from Stockholm by mail order from my supplier Micro Flight Tech.

With the props I will also receive a 2S LiPo pack, so all options will be available, including change of motors to generic 400's or to the MIG 480's that according to my use of them in a Multiplex Twin Star, will use 11Amps per motor with Günthers on 8 round cells thus claiming totally 22A static.

Tnx for all the good advice I've been receiving, this forum is like gold to electric flyers!

/best regards - Mike

jrb
08-15-2005, 07:26 PM
Have flown a Zagi 400 and Multiplex Sonic Liner on 2S with their respective stock S400s, close to 6Vs.

The Zagi with a Master Airscrew 6x4.5 & 1st Gen TP2100s; performance was down a bit from the 8x500ARs, but not bad.

With Gunthers (5x4.3) on the Sonic Liner was & 2nd Gen TP2100s (TP4200-2S2P); it pulled the same 25 amps @ 7 volts as 7x2400. More prop like above would be better.

The 7.2V S400 was the stock system in the X-250 on 10x500NiCd, and I’ve heard that it holds up well with very good performance on 3S w/Gunther.


Go for 3S and 7.2 with Gunthers; up it to 6x4.5 if you need a bit more; motors a quite abit less inexpensive than any other option.


BOL,


Jim


Gave considered the Aventura II; seem a bit pricey though?

Aerowhatt
08-15-2005, 09:18 PM
Don

One is a modified ACE Simple 400. The fuse is slimmer (motor and battery (3s tp2100) have no clearance) and the wing tips have add ons, increasing the span a tad but mostly for cleaning up the aerodynamics at the tips. I changed the angle of attack on the wing a bit too.

The second one is a custom design with a very thin profile airfoil designed by a friend of mine. It's cleaner than the simple 400 due to a thinner airfoil.

The thing I like the best about the GWS 5 x 4.3 prop is it's flimsy blades. Under high loads the blade pitch flattens quite a bit. The vertical performance is like a variable pitch prop. Instead of cavatating as the plane looses speed, it loads up, flattens it's pitch and pulls longer and higher. Plus I have yet to break one on landing. It performs like several different pitches in one prop. The best of both, pitched for speed and also low end pull in one prop.

Aerowhatt

Aerowhatt
08-15-2005, 09:34 PM
Mike,

Those motors are pulling amps like 4.8 volt 400's or 6V race 400's. Definately not comparable to stock 7.2V 400's. They are already overvolted at their rated 7.2V. I'm not sure you could prop them down enough to run well at 11.1 given the new information on the motors.

I'd suggest stock 6V speed 400's with the GWS props and 3 cell li-poly or 10 cell Nimh. It would be a hot setup for brushed motors without over heating your esc. If you don't have good cooling for the motors then 7.2V motors would be a safer bet. I tend to engineer towards higher input voltage and lower amperage for battery longevity, longer flight endurance, lower system cost and weight, better prop efficiency.

Aerowhatt

willyb
08-16-2005, 12:04 AM
Aerowahatt--I have a twin Adventura that I have been using a 3s1p TP Prolite 2000 lithpoly on. It has the original Speed 400 6v. motors in it. I have had issues with take off water loops, etc. but now it is beginning to get trimmed out and can circle the sky and return with no rebuilding time. The props are Gunther 4.9 X 4.3. My current draw is around 25-30 amps. I have a brushed ESC Wattage 30 in it. I will recheck the amp draw when I get back to the lake, but I was wondering if you thought it might be prudent to replace the motors with the 7.2 400s? It is still flying but I have done only real short flights with much throttle management to keep it from getting hot. The overall weight is down to less than 38 oz. Watts are about 228 on last check. Thanks for the help.

Bill

Aerowhatt
08-16-2005, 02:40 AM
Bill,

Congrats on getting it up and down in one piece. With the TP prolites you have a very low internal resistance battery. That ends up holding it's voltage higher under high amp loads = more total watts. Another variable to your motor prop choices.

The gunthers are a good high thrust prop but not super efficient, especially at high RPM's. The GWS 5 X 4.3 should bring your amp draw down about 10 to 15 % static, even more in flight. I'm not familiar with how much cooling air gets to the motors on the Adventura. If it's pretty limited you might be better off with the 7.2V motors. I'd try the props first though. ESC's have no problem running at 70% throttle and up, all day long. If you stick with the 6V motors/GWS props and throttle back a bit more than you would with the 7.2V motors. You will still have that extra depth of thrust when and if, you need it.

Another option would be to prop up some 7.2V motors to GWS 6 x 5 props yielding a tad more thrust at the same watts in, as the 6V/5x4.3 combo. The bigger prop is a little more efficient. If motor heating is the concern then the 7.2V with GWS 5 X 4.3 props would be the ticket with less reserve thrust for emergencies than the other two combinations.

If you want to stick with the gunther props the 7.2V motors would give you some insurance on burning them out prematurely.

Hope that's more help than added confusion ;-)

Aerowhatt

Aerowhatt
08-16-2005, 03:16 AM
Ok, so I live in the high desert and nearby water for flying just hasn't existed. A recent urban river project promises to change that so I'm looking at different available kits because I've always wanted to fly the water.

I have a wonderful 4 channel high wing plane powered by a Mega 16/15/7 motor, Hacker 18A ESC, GWS slow flyer 8 X 6 prop on 3s 1800 to 2100 li-poly It weighs in at 26 oz all up, ~154 watts, static in. The thing jumps into the air off of wheels in the grass. I'm sure it has the pull for taking off with floats. Trouble is, I've never flown off of water and it just looks like a seaplane like the twin Aventura would be much easier to handle taking off and landing back on the water than floats added on to my existing plane would be.

I'm looking for critical owner reviews of the twin Aventura and also feedback on whether or not it's significantly harder to fly floats than a seaplane specific design like the Aventura off of the water.

Aerowhatt

donjiskra
08-16-2005, 01:00 PM
http://www.rcgroups.com/links/index.php?id=4798

This will provide some answers for you.

I've flown with floats on a high wing (Bonnie20) and hulll (Aventura). It's ton's of fun either way.

I like the esthetics of the Aventura design much better.
I'm still looking for a single motor version and installing a brushless motor.

Thank's for all your very knowledgeable support to this forum.
Hope the review will be helpful.
Don

donjiskra
08-16-2005, 01:27 PM
Aerowhatt,
Here's information that REALLY enlightens.

http://www.rc-float-flying.rchomepage.com/Float%20Flying%20Article/floats.htm

jrb
08-16-2005, 08:14 PM
Multiplex 6V S400s run in reverse (pusher) w/Gunthers on 3S 32amps @ 11volts; not likley to last very long!

Aerowhatt
08-18-2005, 04:08 AM
Thanks for the links Don!

Some great information there. It leads me towards a hull instead of floats. My runway will be north - south with about 30 degrees leeway east or west. So I won't always be able to take off and land directly into the breeze. That kinda makes floats too dicey.

I think I'd rather have an Aventura as a single motor (brushless and lighter). From the full scale model it looks like it was a pusher, if so the balance issues are going to be worse. Some with the twin motor version seem to be adding nose lead. A single pusher would make that even worse! I refuse to own airplanes that have to haul lead around to balance. Lighter is always better for flight performance and I'm also going to have a rather limited water surface to work from. (I did read that lightweight = some skipping on landing. But I'll accept that over risking running out of water on takeoff)

Any information on balancing the model as a single motor?? Seems to me from what I know now, it would take some redesign to avoid balancing with dead lead in the nose making it heavier than it ablsolutely must be.

Any input, Ideas?

Aerowhatt

willyb
08-18-2005, 01:45 PM
Aerowhatt:

Thanks for the infro on the GWS 5 X4.3 prop switch for the twin Adventura 6v. motors. I will get a couple and try them out. My amperage is too high now. I have flown it several more times to get used to the lighter weight with the TP2000 pack.

In regard to the single Adventura, I have one powered by a Mega 16/15/4. I have flown it with the TP2000 3S1P prolite pack. By reducing the prop size to a 6 X 4 APC E prop my amp draw was 21.7, about max for the Mega 4 turn. The weight was 26.7oz, down from the 30-35 oz. I had with older Nicads and lithpolys.

I personally at this point do not enjoy flying the single Adventura as much as the twin. It has a very high CG and with even less battery weight in the hull probably has moved the CG higher, with less self righting pendulum effect. The motor weight is way up on the pod and it tends to be jerky in turns due to being rudder only. I have added exp to the rudder and it helps some. If you do find one and build one I would put in ailerons like the Adv. twin and reduce the dihedral. Also the twin floats are shorter. The twin is real stable in turns with ailerons, the cg is lower due to motors being in the wing, the floats don't get caught as much resulting in a water loop as much, etc. I have found that moving the tip floats way out to the end on the single gives a little more water clearance and less water loops, as the dihedral helps get more clearence. The twin has a slot in the aileron for the float to be attached to with a rubber band so that spot is fixed.

With either of these two hull designs I have found that they are best flown on very calm days. I fly off a large lake and the only time it is really calm is late evening or early morning, if then. A 2-3mph wind is about max. The twin will fly easier in a light wind than the single for me. The big problem is that on take off if one of floats even touches the water it spins out. It takes only a small wave to catch it. Maybe it is just me but that is the way it seems to work out.

On the other hand my Seamaster slimer is a breeze to fly in wind up to 8 mph or so. So is a Sig Sealane, but it tends to submarine more than the Seamaster.

One of the most stable flying seaplanes I have seen is the Aerophibian from Hobby People. It is a dream to fly, high semisemmetrical wing, fast with 46 slimer in it, and handles wind on landing and takeoff real easily. I guess I have had good luck with water handling of conventional floats.

I saw the Bonnie 20 perform in the same manner. It looks like a nice plane for some windy weather flying, with its semisemmetrial wing. Perhaps you have a more sheltered place to fly, and if you have calm water the Adventuras really are neat looking and fun.

Again thanks for the help. Float flying sure is fun, until we dunk!

Here are several pics of the Adventura Single.

Bill

Aerowhatt
08-18-2005, 06:56 PM
Thanks Bill

So they made the single Aventura a tractor instead of a pusher like the full sized version. Ailerons are a must on any airplane for me. I never have understood why they train new flyers on rudder only ships. It just teaches bad habits IMO. I train whenever I can get somebody to pay me for it. Buddy box, ailerons and a 40 minute battery.

Well it looks like I have a couple more planes to check out. This feedback from experienced water flyers is invaluable. Perhaps the Aventura isn't the right boat for me since it's rarely completely calm here. I'm not much of a fan of the clark Y airfoil anyway.
Aerowhatt

donjiskra
08-19-2005, 03:37 PM
Bill, thanks for calling attention to the previous incorrect ecalc data, which indicated only one motor.
This screen capture is now indicating data for TWO motors, which is significant.
Regards,
Don

elhepilot
08-20-2005, 04:12 PM
I have tried the stock Twin Aventura with 2S 1500 mah Kokams, 4 batteries in parallel (2S4P) and the Carbon fiber Gunther (Zagi) props. Performance was not that good. It flew but long takeoffs etc.

I then switched to 3S 2000mah Kokams, two packs in parallel. Good performance, quick into the air. I was using a Great Plains C-30 ESC and it would shut down the motors after about two minutes. Tried lots of throttle management but still would shut down. Checked apms with Astroflight Wattmeter. Running about 28 amps!

Since I has a second C-30 sitting around, I put each motor on a separted ESC and now it does not shut down overheating. However, I do not expect the motors to last long like this.

I too plan to get some GWS 5X4.3 props to try.

r_kopka
08-25-2005, 05:21 PM
My Aventura III (Twin Aventura), 2 x speed 400 powered seaplane, gunther-props with Jeti 45A ESC suffers from ESC overheating after a few minutes.

The fuselage being a closed space due to prohibiting water entering the fuselage seems to be a problem, thus the lack of fresh air cooling for the ESC seem to cause the ESC overheating.
...
BTW it's powered by an E-TEC 3s2p 1200mAh=2400 mAh, 11,1v LiPo ack and in order not to fry the motors I have limited the throttle travel to about 22 Amps max and about 200 watts according to my Astro Watt Meter.
I have 400/7,2V motors and use a 3s pack similar to yours. The ESC is a 25-30A(?) type, and I have no problems, After 10mins and ~1600mAh used the battery is a bit hot ~40-45°C but no other problems. Of course that means an average current of 10A. I use full power only for short times. Max Amp should be at 20-25A.

Maybe your ESC doesn't handle half power well.

RK

elhepilot
08-25-2005, 08:13 PM
I have 400/7,2V motors and use a 3s pack similar to yours. The ESC is a 25-30A(?) type, and I have no problems, After 10mins and ~1600mAh used the battery is a bit hot ~40-45°C but no other problems. Of course that means an average current of 10A. I use full power only for short times. Max Amp should be at 20-25A.

Maybe your ESC doesn't handle half power well.

RK

The Carbon Fibre Zagi props may be too much for the motors. I am waiting for the GWS props refered to previously. Maybe the amps will go down.

electric mike
08-29-2005, 08:39 PM
The Twin Aventura now ready for test flight!

Finally got my new Graupner 400 7,2 v motors, with the removable external stator rings mounted. Current was at 22,5 Amps total for the two motors, APC-E 6x4 and 3S2P LiPo 2400mAh at 10v at full throttle, pretty much just what I wanted!

Obviously there is a big difference in current with the 6v and the 7,2 v motors, especially when running on the rather high voltage that a 3S LiPo pack will produce.

Also tried the Graupner 400 6v motors without stator rings, and they strange enough consume 72% more current on full throttle than the 7,2 v motors with stator rings. I thought that the difference would be much smaller.

Earlier, after the original current-consuming MIG 400 setup with APC-E 6x4 props, I tried the small GWS 5X4.3 props on 8 round cells, and the current only went down from 26 Amps to 20 Amps per motor! That's a total of around 40A for two motors. Not good!
Even running the GWS props on a 2S LiPo, the current was way too high.

So the Graupner 400 7,2 v with stator rings and APC-E 6x4 are definitely my choice now.

Also mounted a home made removable landing gear for test flights, and I opened up an cooling air intake on the forward right upper part of the pylon, and an air outlet on the left upper rear part of the pylon in order to provide the ESC with a cooler environment.

Tested the power train by simulating a 6 minutes flying session in my "Skunk Works" workshop with various throttle settings, with full power for takeoffs, decreasing throttle for cruising, and then 20-30% throttle for landing pattern, repeated over and over again, as I will probably enjoy doing continous splash-and-goes IRL.

The JETI 40A ESC, which previously re-armed itself after about 45 seconds of 20% throttle with the original MIG 400 motors, now works flawlessly with the 7,2 v motors and was not hot at all after my 6 min "on the work-bench-test", although the lack of any forward airspeed must have ment that no air at all was forced into the ESC cooling air intake.

So now I am very happy about the setup!
Pictures from test flight will follow.

/best regards from Mike

donjiskra
08-30-2005, 12:48 PM
Mike,Looks like you've solved the problem.Good luck. Let me know how your solution works out in flight.With my Aventura Twin, I opened (cut-out) the rear of the motor covers to allow the hot air to exit.Don

NCguy
09-08-2005, 03:16 AM
Aerowhatt:


One of the most stable flying seaplanes I have seen is the Aerophibian from Hobby People. It is a dream to fly, high semisemmetrical wing, fast with 46 slimer in it, and handles wind on landing and takeoff real easily. I guess I have had good luck with water handling of conventional floats.

Bill

Did they discontinue the Aerophibian? I only saw were they were selling parts on the website at hobby people?

donjiskra
09-08-2005, 12:27 PM
Willyb,
Sorry but I'm not familiar with this plane. Perhaps others can help?

Don

willyb
09-08-2005, 05:18 PM
Here is a copy of the catalog with the aerophib specs. I am not sure they still have it as I couldn't find it on the website, only the replacement parts. If you are interested you might give them a call.

Bill

NCguy
09-08-2005, 05:22 PM
Here is a copy of the catalog with the aerophib specs.
Bill



willyb, for some reason the catolog copy didnt post?

willyb
09-08-2005, 05:40 PM
Will try to downsize image. Click on it and use arrow in right hand corner to enlarge. Hope it works.

Bill

NCguy
09-08-2005, 07:14 PM
Will try to downsize image. Click on it and use arrow in right hand corner to enlarge. Hope it works.

Bill

Worked great ! Thanks. I was able to compare specs with the Bonnie 20. Looks like a nice plane but apparently, at least as a glo, its almost twice as heavy for about the same size airplane. It does have a larger wing than the bonnie but the wing loading is still subtantially higher. I wouldn't think as an E conversion it would be any lighter than the glo version. Very likely it would be heaier.

I really like the fact that it comes with the floats and you dont have to make struts etc like you do with the bonnie 20. Don't know yet if its still available.

willyb
09-08-2005, 11:32 PM
NC guy,

Yeah, I agree. I was going to buy another Airophib for an electric conversion but decided it was too heavy too; also it would take a lot of homework to fiqure out what to put in it for a motor, battery, etc. The larger batteries can get pretty pricey. Where I fly the Airophib gas, a fellow had a Bonnie 20 on 31" floats. He was having a ball and it flew similar to my Airophib. He was using NMHYD batts and it was somewhere over 3# I would guess. For this reason I decided to buy the Bonnie. The floats were backordered so I have been flying it off of grass. I am using a TP2000 prolite pack with a Castle 45 amp ESC. It has an AXI 2820/10 motor. My flying weight is 2# 15 oz. I decided to go with the 27" floats that Hobby Lobby recommend for the Bonnie. Bob Aberle has an article about the Bonnie on floats on the Model Aviation Web site. He used the 31" floats. I thought with my Bonnie being lighter there would be less drag with the smaller floats and aerobatics might be easier. My 27" floats came the other day and I am getting them ready now. I am going to use the nose wheel steering mechanism to move a float rudder. I will take some pics soon and post them if you are interested.

I also made a modification for the battery. On the Bonnie you have to take the wing off to disconnect the battery. I will send you some pics of the hatch cover I made using a magnet to close it. The Bonnie is a nicely made plane and has a proven power plant to pull it.

Good luck on your choice.

Bill

NCguy
09-09-2005, 12:02 AM
willyb,

that hatch cover looks awesome and I'm guessing not that difficult to build. What did you use to neatly cut out the fiberglass? Also, I'm very interested to see your water-rudder assembly. And am also very interested to see how the 27's do. Please keep me posted.

I'm interested in the Bonnie for two reasons. First, I live on a 22 acre lake and I want a nice flying water capable model. Secondly, we seem to have a lot of students lately that are interested in doing their training on electric models. If I can get the Bonnie to stay up long enough this may be the best alternative I've seen so far. I will probably be experimenting with some very large LIPO packs since long flight times will be needed for a good trainer platform. Hopefully it wont drive the price beyond the typical students budget.

donjiskra
09-09-2005, 12:33 PM
Wow, nice modification!!!
Thanks for the photos. I too am wondering how you made such a clean cut and how you "preserved" the lip for it to sit on.
Will be interested in your version of a water rudder. I used the 31" Zeedo's and made a "transom" for the water rudder because of the angled slope of the Zeedo. I ran a cable from the nose wheel servo back to the rudder. An alternate way would be to simply mount a servo right on the float. I've seen a number of float planes using this technique and the owners haven't reported any water problems, strange but they claim it works fine. My Bonnie weighed in at 70 ounces with a 4200 ThunderPower LiPo. It really has great speed on take-off and will do rolls, loops and inverted very nicely. It will do 14 minutes at cruise, about 50% throttle.

willyb
09-09-2005, 01:36 PM
Don & NC guy,

Thanks for the kind words. It is an easy modification to do. I just made sure it was wide enough for my widest pack and then went as long as possible without getting too close to the windshield. I drew out some lines for the hatch and figured I could make two tabs that would go under the cowl. I used the real thin Dremel cut off disks. Use a new full size diameter one to do 75% of all of the long cuts as it is easier to get a long straight (somewhat!!) cut with it. Then use a worn down real small diameter one to do most of the tab and corner work. Finish up with a #11 blade as there won't be much cutting left to do. Then make the the tabs a bit smaller and you may need to add a filler over the bulkhead to keep the tabs up in place as there is quite a bit of space there. Then I added some scrap balsa aound the sides to make the cover depression a bit more firm, really not necessary. Make the steel plate for the magnet out of tin can stock or one could use a second magnet. At the end put the magnet on the plate and a small amount of epoxy on the magnet to fasten it to the the top cover. Then after it is firm add more epoxy around the magnet. I used a piece of scotch tape for a lift. If you look carefully you can see it on the third picture. One could consider using an even stronger larger magnet from the outside to pull the hatch up, a "special tool". On a scale plane I am making I put an external metal plate to use a "magnet tool" on to open a fuse electronic hatch door. One can paint over that metal plate. One could get more fancy and make a silicone hatch gasket I suppose. There will be a little space and if any water gets in I will put scotch tape over the seams. I sure go through a lot of scotch tape as one has to take the Adventura's windshield on and off with each flight! Using scotch tape is one of the benefits of electric flight! I like the idea of being able to disconnect that battery right away rather than taking the wing off to get at it. With the Lithium Polys, my battery has to be as far forward as possible. I use a single 3s1p TP2000 prolite and that gives about a 5-6 minute flight safely. NCguy, if you are going for real long flights you may want to go with a larger battery like Don is doing. Then I would sure go with the 31" floats too.

Don, thanks for the photo of your rudder. I have an Ernest 40-60 size rudder but I think it is too large. Did you use the smaller size? I will check with my LHS and see if they have the next size down.

Will post pics of the rudder steering I am doing soon. It may be easier to do as you did, Don. It is fun to try different things. Sometimes, however, they don't work out!

Bill

donjiskra
09-09-2005, 04:01 PM
Bill,
I used the smaller unit, which is perfect for the Bonnie.
don

NCguy
09-09-2005, 07:42 PM
willyb, thanks for the detailed explanation! sounds very well thought out. Just a couple additional questions.

I'm a bit confused about the tab construction. You must have made the tabs out of fiberglass or ply and then somehow attached them to the bottom of the hatch? From your bottom side pic they dont look attached, they really look like part of the hatch itself?

Does it seem like a larger (longer primarily) battery would work with the removable hatch? Is there room to manuever it in and out?

willyb
09-11-2005, 02:29 PM
NCguy

The hatch cover is all one piece, no add ons, just cut out of the fiberglass fuselage. The fuse has a wrap around fiberglass front that is indented to hold the cowl. The motor is in the removable cowl with the firewall for the motor up front in the cowl. Here are several more pics of it. You are right, the hatch cover is all one piece. The fuse is all fiberglass, really nicely done. The hatch cover is just cut out of the fuse. Making the small tabs come out right is easy. Just draw the cutting lines on the fuse with the tabs as shown; the tabs will then fit right under the cowl after is installed with the 5 screws to hold the cowl and motor to the fuse.

Let me know the battery dimensions that you plan to use and I will make up a mockup and see if it will go in. I am using a relatively square TP2000 Prolite and also a new more narrow but longer TP2100 Prolite; both are 3S1P. If you going to use several different size packs, if you have a real long one you could still put it in by taking the wing off.

Hope the pictures help.

Bill

NCguy
09-11-2005, 07:06 PM
NCguy

Let me know the battery dimensions that you plan to use and I will make up a mockup and see if it will go in. I am using a relatively square TP2000 Prolite and also a new more narrow but longer TP2100 Prolite; both are 3S1P. If you going to use several different size packs, if you have a real long one you could still put it in by taking the wing off.

Hope the pictures help.

Bill

Thanks Bill, that does help alot. I appreciate the photos also. As soon as I've settled on the final battery I'll pass it along. Right now I'm thinking it will probably be a prolite 3s2p or possibly a 3s3p if it will carry it.

Thanks again.
Ted

elhepilot
10-03-2005, 04:06 PM
Tried the GWS props on the stock Twin Aventura. Flies great and does not seem to over power the motors and ESCs. I will report readings (amps) when I can.