Seagull 61" Sparrowhawk to be Christmas Build

Hello Garry, Thanks for the reply(s).
To answer your questions:-
1, Yes I have a watt meter but haven't used/tried it yet -- it is a HobbyKing HK-010 with XT60 connectors--- so I need to make up some "interface adapters" as I don't have many batteries with XT60 connectors!
2.The Seagull Sparrow Hawk I bought came with the electric motor fitted using the "free electric conversion kit". So I don't have to do the engine mount and plywood battery access hatch arrangement as that is all done. Looks pretty good actually. The only problem I have at he moment is trying to fit my existing batteries in the space allocated. There is a lot space in the model itself, but, looking at the current C of G situation, I need to mount the battery as far forward in the cowl as possible (and this starts to limit the battery size/shape) to minimise the amount of additional lead it looks like I am going to have to add to the nose area (currently about .36Kg which I think is quite a lot I need to squeeze just behind or above the motor).
3. The motor that came fitted to the model is a NTM 50 PropDrive 50-50 580kv. Don't know if that is any good. The very few internet search returns I have found on this engine seem to suggest it is no longer available and are rather mixed on its performance/efficiency/reliability.
4. I am researching an appropriate ESC. Currently thinking about a 70A (Continuous) size.
5. The a/c came with a 14x 7E prop. Don't know what variety......but I am expecting that I might need to get a range of props ( 14x8, 15x7, 15x8 etc) to try.
6. What sort of RPM do you think I should be looking for at max throttle/volts? I have a number of 6S batteries (from my helis) that I was intending to use. I hope 6S would be OK as I don't currently have any 5S batts. Most are 5000mAh size but these are a bit big to fit in the allocated space (see 2 above). But I do have some 3000mAh 6S batteries that would just about squeeze in the space -- I just hope that they would give reasonable flight times. and won't cause the ESC to overheat if I need to throttle back a bit.
7. The all up mass of the of the a/c is coming out at about 3.68kgs (inc lead and 70g ESC allocation, but exc batt). 6S 3000mAh batt is about 0.467kgs. So total is 4.147kgs. This might increase further if I decide to go for a separate RX/servo battery pack rather than go for a BEC.
Hope this answers your questions ...... so you can give me a few pointers thanks.
Meanwhile I will think of something to write about myself and then i'll pop over to the "introduce yourself" part of the forum -- assuming I can find it--- I have only really got to this thread and the registration part of the forum so far.
Cheers
H31

Eric, sorry to have to say this, the post you posted at 18.14 was one of the best I have seen on explaining elec, cant see you missed anything out .Well done mate

Garry

Ok Richard
Here are the specs for the motor

Specs:
Model: NTM Prop Drive Series 50-50 580kv
Kv: 580rpm/v
Max current: 90A
Max Power: 2000W @ 22.2v (6S)
Shaft: 8mm
Weight: 347g
ESC: 100A
Cell count: 4s~6s Lipoly
Bolt holes: 30mm
Bolt thread: M4
Connection: 4mm Bullet-connector

So....it will blow your 70 amp ESC at full throttle, you need a min of 100A, and I would go a touch higher. assuming you are going to use the 6s lipo. A 3000 mah will give aprox5 to 6 mins mixed flying, but being old I work in old money, so model will come out at 10.5 Ibs and motor will/should give 2000 w As Eric says, 100 w per Ib, you will be overpowered, but you have a throttle stick, so you do not have to go flat out . A further question is are your flying skills up to this sort of a model ? This is the reason we ask for an info post

Garry

Here is a video of your motor being tested with a watt meter used



Hope this helps, if not,ASK !!!!

Garry

I wouldnt worry about the revs Richard, but all things being equal it will be 580 x 22.2 580 is the Kv and 22.2 v is a 6s lipo,

The reason I say dont worry, is that this will work out at close to 200 w per Ib Wish I was on the sticks. I fly these sort of models

Garry

Crikey, You guys are quick and helpful!
I am sorry Eric that the info in my second (ever!) post arrived a bit late -- I think our posts were crossing "in the web" whilst I had been summoned away by "senior Management" to have my tea.
... Just bear in mind, my first (ever!) post was really about thanking "The Beard" for starting this thread and all the useful posts within; then following up with a query trying to understand the proper/optimum C of G position for this model. Hopefully "The Beard" will stop by soon to help out on this to help me crystallise the extent of my lead/nose weight issue.
It wasn't until I saw Garry's initial reply to my first post that prompted me to add a touch more detail on my project and only now I realise that this forum and all knowledge and experience of its members could really help me sort out the "power train" side of things.
Thanks
Now where do I find that "Intro Yourself" part of the forum? Let's try the search facility.

www.aeromodellers.co.uk/forum/thecafe/10...art=1425#forumbottom

Garry

Thanks for the intro Richard. Now we are getting somewhere. It would be interesting to know what part of the country you are in. I can now see you are not a novice trying to fly something you couldnt handle .This we have to be very careful of as bad advice could cost a newcommer a lot of money and the forums reputation.
.There are lots of videos on youtube on how to set up a fixed wing power train, so the next thing is, have you any further questions ??

Garry

you will love this model mine is gorgeous but still not relaxed yet when I fly it mine is IC

Must say I had to read Klippy's post a couple of times before I realised he MUST be talking pitch not length. However, cant agree with Eric, as I have a similar motor which has been running on a 14 x 7 E prop on 6s . Next time I get it down, I will put the watt meter on it. It goes like stink on full bore and is oos in vertical

Garry

Hi,
Have opened a new thread here:-

www.aeromodellers.co.uk/forum/model-buil...-electric-conversion

.......to document the progress of my 'SparrowHawk --- electric conversion' and not to contaminate this thread.