AEAJR

Huffy,

Ron's first post gives you all the basics.

I always start with the type of performance I want, to create a starting point for the power to weight ratio. If it is an aerobatic glider you are probably thinking in terms of a warmliner or a hiotliner. I would suggest you target at least 80 watts/pound and more likely 120 watts/pound. Past 100 watts/pound you are going verticle so it becomes a question of how fast you want to climb.


At 100 watts per pound my e-gliders will go up between 75 and 90 degrees. In 20-30 seconds they are very high. That is my target performance.

Get it up to 150 watts per pound and a 10 second run may put you at visual limit.

On a 2M glider I would look for a motor/battery combo that would turn a 10 - 13" folding prop.


Ron,

What do you think?

Tsurwolf

Hey Huffy01

I have converted three Spectra Gliders to run on brushless motors, using different configurations for the tail feathers. One standard One T tail and One all flying elevator, All worked well though the T tail ( 9 grm micro servo in the vertical stab )was heavy and took some lead in the nose to balance, the "all flying tail" did to, those two got 3542 1000Kv outrunners on 3S1P 2200 LiPo's and climb very close to vertical, a 15 sec run puts them way up there where the thermals are, and 30 min flights are the rule rather than the exception.

Any two meter glider can be converted to power assist with a little thought on battery and motor placement to keep CoG in the right place, a lot depends on what you are going to use it for, if competition then get a purpose design as all the kinks will have been worked out, but if just sport flying for fun almost any configuration will work, maybe not as well as possible but working all the same.

Cheers TBBW

Sky Sharkster

Hi Ed + Huffy,
Ed's power suggestions are good. I've flown several 2-meter conversions with (roughly) 100 watts/Lb and they all flew fine. Most were either geared inrunners (or brushed geared motors) and occasionally outrunners.
Ed's also right about the large props. Gliders are large, streamlined aircraft. A bigger prop at lower RPM is the best way to get them to altitude without over-stressing the airframe. This is particularly true if the construction is built-up balsa or unreinforced foam.
Composite-construction models can stand more power and speed, but for starting out they're expensive and unforgiving of damage.
A simple "Speed 600" or geared "400" (planetary gearbox) should be a good starting point.
Good Luck!
Ron

Huffy01

Just have a good look at the plan's at the moment.
First 8 bulkhead's are 3mm plywood and the last 4 are 3mm balsa wood.
3mm x 6.5mm spruce longeron's, 3mm x 6.5mm balsa spine's.
Covering is 3mm x 6.5mm balsa with fiberglass reinforcement from the nose to wheel.
The instruction are to build the bottom half of the fuselage, then the wing centre section, final the top of the fuselage.
The internal set-up from the nose, ballast holder, battery, receiver and three standard servo's all before the wing in this order.
The aileron's are controlled by nyrod's running just behind the leading edge to a nylon bellcrank then to the aileron.
The thing I can understand is the wing attachment. It has to brass tube with piano wire which are glued to the wing former's. Inbetween the brass tube's there are a pair of cup hook's where a rubber band is used ???
As for power!! I think I would go for "Hotliner", so I wouldn't need to upgrade later.

AEAJR

I will depart from Ron on the motors. Bypass brushed "speed" class motors. Yes they will work, but today's brushless motors are so good that it no longer makes sense, in my opinion, to go with brushed motors. And for a high power set-up, like a hot liner, it would be hard to hit the power levels you want with a brushed motor.

I also prefer outrunner brushless motors where possible. Normally you can run them without a gearbox. This makes them quieter and less costly than geared set-ups.

The key with outrunners is making sure you have the clearence for the spinning can. And make sure that nothing will come in contact with the motor. Secure wires out ofthe way, for example.

You can use NiMh batteries, but today's Lithium batteries are so much lighter and so powerful that I also recommend you go straight to lithiums.

Sky Sharkster

Hello Huffy,
From your description, this sounds like an older design of the "Floater" type. Does it list an airfoil? That would reveal quite a bit about the design flight envelope.
Do you know why there are 3 servos in the fuselage? normally there would be 2 (rudder. elevator).
With a balsa spine/keel, the fiberglass fuselage reinforcement is a must. Even spruce will have a hard time handling landing loads.
Another indication that it's an older design is the pushrod/bellcrank activated ailerons. With today's high-output micro servos, nearly all designs use one small servo outboard in each wing panel. That is a modification that I would strongly suggest.
Without seeing the plans, it sounds like a few upgrades would make this design into a reasonable "Sport" powered glider, but I would be cautious about "Hotliner" type power. It clearly wasn't intended for any speeds and flight loads of that sort.
I also wouldn't recommend a "Hotliner" performance goal for a first powered glider. Perhaps as a second or third.
Just my honest opinion!
Ron

Huffy01

There is no airfoil listing, just a rough guess it could be Clark Y, all rounded with 3/4 of the airfoil flat underneth to the trailing edge.
The third servo is for the aileron control.
I think you are right about it being an older model.
I will try to get a pic when I find some batteries for the camera.
The plan are just one huge sheet of paper 2000mm x 900mm. Not alot of instruction on the build sequence and nothing about attaching top half fuselage to the bottom half of the fuselage.
I have been thinking of modification's already ,aileron's were one.
Airfoil's are another. I have "compufoil3D" on my computer so I can redesign wing's and then print them out with the printer.
There's also the wing mount's, I just worked it out. 2 brass tubes in both wing's with snug fitting piano wire. Then 2 cup hook's with a rubber band stopping the wing flying out.
This is my second glider .I've got a Parkzone Radian, been flying it for close to 4 month's, I want too upgrade to aileron control and something faster, more suited to aerobatic!

AEAJR

It will be fun to follow the electrification process. Do you plan to start a build thread?

Does the glider have a name?

Huffy01

Here's some photo's of part of the plan. I only got these 4 before these batteries went flat.
The plane is called "Swift" .
I might as well start a build thread but it will be a couple of week's before I can start. Monies a little tight and it takes 5-7 day's for Paypal too accept fund's.

Sky Sharkster

Hello Huffy,
If I'm understanding your goal correctly, you're looking for a powered glider that is capable of aerobatics, can also thermal well and has a fast rate of climb.
If so, here's a couple of ARF's that will perform well in these areas;
http://www.espritmodel.com/index.asp...OD&ProdID=3803
http://www.espritmodel.com/index.asp...OD&ProdID=2842
And there are others. Another type of fully-aerobatic glider is a modern Slope glider, like the ones I linked earlier.
Now, if you plan to build or convert an existing design to meet these design specifications, it will help to see what they're doing and how they're going about it.
Notice that neither model has built-up wings. They're foam-core, carbon or fiberglass reinforced and one is balsa-skinned.
Built-up wing gliders (often called "Woodies" or "Crunchies") generally aren't strong enough to withstand "Hot/Warmliner" type climb speeds and stresses. There may be a few, but most performance powered gliders use composite wings, not open-balsa structure.
Virtually all powered gliders designed for high-performance use fiberglass/carbon fuselage. Again, balsa sheeted structures (unless heavily reinforced) won't take the stresses of torque, thrust and aerodynamic loads imposed by these speeds. Hotliners climb at nearly 100 feet per second! Think about (just) the flight loads on the wing/fuselage joint.
Even if the fuselage can stand the stress, the real killer is wing flutter. Both torsional and span-wise rigidity must be absolute.
So, I'm not saying you can't convert an existing thermal or aerobatic glider into a powered glider that will meet all your goals. But it should be done with full knowledge of the inherent problems and using solutions that have been proven.
Good Luck!
Ron

Huffy01

Before I bought these plans, I went looking. I found this link on a thread in wattflyer and added it to my "list". I was looking at the Great Planes Siren but decided it would take along time to finish.
Anyway ,just thinking about fiberglass reinforcing. I could build the fuselage skin with thinner balsa. I know the company that sell's balsa start's with 0.8mm balsa sheet.
I could do a balsa/fiberglass sandwhich.
I think the wing might be a little more difficult but I could do roughly the same.
I have some expanding foam but that might be even more difficult then fiberglassing 2 side's of a wing.
On youtube I did see a slope soarer, trying to clock 300mph ,break apart.
The speed just ripped one of the wing's off, The rest of the plane spiraled down the valley.

Huffy01

I was at my LHS today buying some plywood when I was asked what I was building. When I mentioned the "Swift" he knew about the model and owned one. He showed me a few photo's. His was made of fiberglass ,he also added a retracting landing wheel.
He did say it was "a little bit floaty" but still handled like a pattern aeroplane.

cbatters

Working on a weight reduction for my Electrosoar 2M EP (similar to a TowerHobbies EP Vista) and would like to install lighter servos, receiver and ESC. (Full size servos are neary 45 grams and full size RCD receiver 38 grams)

Any recomendation about smaller servos (no specification in the documenation about torque requirement bt have noticced that E-Gliders like the Radian use MUCH smaller servos PKZ1060)



Clint

Sky Sharkster

Hi Clint,
Here's my first choice for servos stronger than "Micro".
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXN676
HS-81's, the Ol' reliable. For pushing a cable or pushrod 2 feet (or more) on a large glider, this is the ticket. Weight is 16.6 grams, 1/3rd the weight of the old ones, 36 oz/in of torque on 4.8v volts, nearly 42 oz/in on 6.0 volts.
I wouldn't use "Sub-Micros" or servos with less than 25 oz/in for this application. On a "T" tail with rear-mounted elevator servo, maybe.

If you're flying 72mHZ FM, my choices for RX's would be;
http://www.castlecreations.com/products/berg_ms4.html
http://www3.towerhobbies.com/cgi-bin...&I=LXRSS1&P=SM
JMO,
Ron

misterv

Instead of startng a new thread,it would appear that someone here may be of assistance.
Firstly let me explain that we are a couple of very experience and competent modellers havng flown helis,F3a,1/3 Scale.IMAC and turbines, so we know how to fly, build (now assembly) and trim a model. We decided to dabble in electrics and have had success with electric converted slope soarers, then decided to buy both the ASK28 and DG1000 from Hobby King.Very satisifid with the design and quality and especially price.
As to the DG1000 this has been assemblied correctly,balanced,trimmed and fitted with the recomended equiqment-Turnigy 38-48-B-900kv. motor.60amp ESC. 3600 3 cells lipo and 13" X 7" folding prop,Spektrum 2.4 radio.Weight is as advertised. Motor is producing around 350 watts, with excellent performance.
Maiden flight was excellent with the performance as expected with the exception of the hand launch. This and all subsequent launches have been near disasters. The torque drags the aircraft sharply to the left and if not for a very quick acting controller it may have ended there. Others have tried launching with the same results. The narrow, high aspect wing has not enough area to counteract torque until forward speed is obtained.
Is this a common problem with this type of model and how can it be overcome?
Would it be practiable to launch without full power applied. This is about the only idea we can come up with and with trial and error (not much error) could a compromise between power and torque be found. OK the model would sag for a split second and power supplied gradually.Any suggestions would be appreciated.
Again not having experience with this type of model, very high aspect wing, we found the model had some odd habits while flying, mainly on reduced or no power. It is fast and smooth but appears to stall at quite a slow to medium speed and although it can be recovered it does not feel as you are in complete control.
On a fast glide at about 150 ft. altitude it again appeared to stall, not a usual stall but the only way to describe it, is the model rotated similar to the hands of a clock,sitting vertical, rotating with no forward speed, dropping and hitting the ground with very little damage.It definately was not a radio problem and although it was over in a second, you could see no signal or power could correct it.
We realise that it is only lack of experience with this type of model and can be overcome, but any help would be appreciated.

constantCrash

When hand launching an electric plane, it's common (recomended) to not use full throttle as it will result in a torque roll into the ground. 50-75% power is usually used until the plane is flying.

What ESC are you using? one of the primary concerns with Spektrum is makeing sure the system has good power to it as a drop in power can result in momentary loss of control. That could explain your second issue. If you've got your motor set to Break on, it could be drawing enough power to brownout the ESC if your using it to supply power to your servos.

Having said that, I don't fly gliders. but the problems your experiencing are not limited to them.

AEAJR

Always helpful to provide links to all the devices you are discussing. You make the assumption that we are intimately familiar with all the components, which we are not. Just a tip for the future.

Yes this is common with scale models.

ALL planes, regardless of type, have no control till the plane has enough speed to develop lift and enough airflow over the control surfaces to provide control. I have no idea what your glider weighs so I have no understanding of your power to weight ratio.

I have no idea of your weight or your wing area so I hav eno idea what your wing loading might be.

What you describe is a stall. You are not getting enough air speed on launch. Have you had successful hand glides with the motor off?

Hand launching a scale glider can be especially hard as it is very hard to grab it in order to give it a good hard throw. This can be helped by a very powerful motor set-up but even that has to get it flying before the wings have any lift.

One approach is to put a hook on the bottom about half way between the nose and CG. Then use a bungee to help get the plane flying then turn on the motor once it has cleared the bungee. This is common on flying wings which suffer from the same difficult launch issue.

I have used this approach with success in the past.

If you believe the problem is not stall but torque you can try launching with partial throttle. If you are able to get a good enough throw to perform a glide from a hand throw then this will work just fine. Or, use the bungee approach.

This is far to vague to be helpful, especially since I know nothing about the plane, the weight, the balance point or anything else. I need links to the plane and I need its all up weight as barest minimums.

How do you stall in a fast glide? That makes no sense.

How do you have no forward speed in a fast glide?




Provide the information requested and as much more as you have.

john339

I agree that you should try a partial throttle launch and see if you still have the same problems. I had the same problems with my Easyglider Pro that I overpowered.
I went to a Turnigy TR3548 Turnigy Plush 60 amp esc turning a 10x8 folder
Low throttle on launch and then gradually more to get er up there and then slowly lower it and float.
I use a camera, a Panasonic Lumix DMC-FX07 to take video.
I had to edit out the parts where the prop was turning and decided to make it a pusher.
I now can video and there is no prop spinning in the middle.
I had a lot of people tell me how to set the pusher so it would still act like an airplane under power and not dive or immediately crash.
I am very happy with the performance now and much less editing of videos.
Our 17 year old Chihuahua mix was indifferent to my success since it didn't have anything to do with food...........
So in ending this long missive.
Launch with partial throttle and give it a good shove then slowly add throttle and as it gains speed it will respond better and better.

misterv

I thank you for your replies and information and apologise for not giving your full specifications of this model. I thought that with the activity of Hobby King in Hong Kong with his unbeleivable stock quanities and unmatched prices,this model would have been know. At US $100.00 for a top quality 2 1/2 m. salplane it is a steal.He sold over 80 in one month and same quanity of ASK28. Here are the advertised specs :-

Specification;
Wing Span: 2630mm (102inch)
Weight: 1,000 ~ 1100g
Length: 1130mm (44.5inch)
Wing Area: 28.5dm2
Wing Loading: 33~35g/dm2
Airfoil: HQ 3012

Required:
Radio: 4 channel, 4 servos. (Ail(2 servo) / Elev / Rud / Throttle)
Motor Required: Inrunner or outrunner with a maximum diameter of 36mm
Spinner: Around 38mm diameter or smaller.
Made by FlyFly in China. Quality outstanding.

My model is 1180g.weight.

Firstly in reply, I am familar with the battery requirements of JR.Spektrum 2.4 and this model if fitted with a seperate Lipo123 battery of 6.6v. for receiver and servo power.
This eliminates any problem caused ESC draining power to Rx.

The launch problem is definately caused by torque initially and because of almost zero forward speed a stall results. Quick reaction picks the wing up immediately. Being use to flying F3a, turbines and fast slope soarers, I am use to having ample power on hand to get out of nasty situations. I choose this model because it looked like its scale speed would be fast and smooth and so far it is excellent in that regard. I beleive it may be overpowered or over propped.
It is much too large to test glide without power. At least by anyone I know with a strong enough arm.
I will take your advice and use around 66% power for future launches, gradually power up and the set for crusing speed. This model is not a thermal floater and designed and weighed for the slope. I note in the UK the same model is fittted with a weight saving cardon-fibre tube whereas this model has a silver steel brace for inertia.
Regarding its odd behaviour (to me anyhow), I have used a flight simulator with a approx. size and type of model and note that the stall is exactly as descibed in my case. Long wing tumbling action, all over the place. This occurred at a faster speed than I thought but is only a matter of getting use to the type of model. I'm used to the larger models where the stall, if any is very predictable and recovery known.

Thanks again.

bernjo64

Hi,

I am planning on converting a Sig Riser 2M to Electric power and am wondering if the Airtronics Park Flyer receiver is going to work OK. I am primarily concerned about range, as I expect (hope...thermals providing) that I will be flying this plane higher than my gas plane, which has the regular receiver.

Thanks in advance for any help,
Bernjo64

prof_fate

Interesting thread. Just tagging mostly.

A decade ago I attempted to teach myself to fly with a windstar EP 2m electric 3 ch plane. I discovered that I needed more room, better radio and more money...so it got put away.

I plan to pull it out and 'restore' it next spring, losing the old nicd/can motor system and going brushless/lipo and 'modern'. Not sure about the servos -it has some (now ancient) futabas in there but hey, there in there so why mess with it? Just kidding - a couple of new servos is cheap enough (these days -been a good 10 years).

mred

I would say forget it. A 2M glider is capable of easily going higher then that receiver is capable of working at. I have had my 2M Chrysalis at 2150ft and that is beyond the ability of park flying gear. If however you only plan to fly up to about 200ft and maybe 400ft horizontal from you, then fine, but I'll bet you can't keep it there and will go beyond that. It would be very easy to go beyond that and not even realize it. Unless you don't care about keeping that glider very long, I would get a new receiver and make sure you have the proper equipment for flying a good glider.

Even a 2M Riser is fully capable of making some fantastic flights and out flying a park system. Play it safe and get a good system. Then you can sit back and really enjoy that glider.

If you are looking for a motor, then consider a KD A22-20L. It is a 200 Watt motor and using a 10X6 folding prop is just about perfect for a 2M glider. I have been using that motor for about 5 years now and I couldn't ask for a better motor for a 2M glider. You can get one from Hobby King and it cost around $15.00, so you can't beat the price either. If you have any questions about installing a motor, then don't be afraid to ask. Someone will help you with it.

Ed

prof_fate

Being somewhat new to flying I've no way to guesstimate how far away a plane is...can you even see them at 2000+ feet?

What do you rec for a radio/receiver? I was thinking of a Dx6i, spektrum 6100 and a satellite receiver, and possibly bec and seperate rx batt so if I do run the motor batt down I know i'll have tons of rx batt left.

AEAJR

* if you run a Lithium motor battery down enough to lose the RX you will have ruined the Lithium battery.

* What radio you use is a topic all unto itself. To fly a 3 channel electric glider you can use just about any radio.

As far as seeing your glider at distance, well it depends on how large your glider is and how good your eyes are and the atmospheric conditions. Also the colors you choose will impact how well you can see your glider at distance.

I fly 3-3.5M gliders at 2000 feet altitude and as far as 1/2 a mile away, but at that distance they are literally dots and pretty hard to see.

2000 feet straight up is not hard on a 3.5m glider

A 2M glider would be harder to see at these kinds of distances but there is no correct answer as it is all dependent on the plane, the pilot, the angle and the atmosphere.

prof_fate

If you draw too much power through your ESC it can cause it to shut down or reset, this will shut the power off to the RX if you're using your esc to supply the power to your rx. This is called a brown out and isn't all that uncommon.

There was some discussion on this in another thread, specifically about servo amp draw and that some can pull 2a each - get 4 working and you can have 8a draw just from the servos - if your motor is pulling 15 and you have a 20a esc you can have issues. I've had this issue with my rock crawlers and had to go to a castle bec to eliminate it.


Radio vs receiver - the signal strength coming from the radio is very important - if you can't get the signal to the receiver the best receiver in the world won't help you. You can have signal loss while taxiing if you get the antenna pointed 'just so'.

I assume (and we know never to do that) that all TX put out the same power...but I'm guessing a $169 Spektrum is likely to be better than the 'free' airfield radio I got with my T28, or perhaps better than a $40 flysky radio - but that's just a guess as I'm guessing a $50 brand name receiver is better at receiving than a $5 orange clone one is.

Regarding altitude - are there are rules / laws about where you can't fly - within X miles of an airport type thing? For parkflyers i'm not concerned - 200' isn't that high, but as the crow flikes i'm not too far from a small airport and have had real planes over my house, heli's and even the goodyear blimp at well under 500' altitude. I'd be able to get my powered plane out of the way I"m pretty sure, but a bigger, slower, higher glider has me a bit more cautious or concerned.