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John Tee22/06/2019 13:41:14
792 forum posts
65 photos

I've converted my replica Veron Robot form I/C to electric. Still need to adjust the downthrust but flies quite well. The problem I now have is that on the landing approach the prop is windmilling. Not really sure if it affecting the landing speed as such but each time I have landed as an elecric model I have broken the prop, no U/C fitted. Model is rudder and motor only - no elevator ( built for our clubs 50th anniversary vintage day last year). What would be the effect of setting the brake to on without a folding prop? would there be too much drag or would the prop stop at a random position and still be prone to breaking. May have to fit an U/C and rebalance. Haven't had time to try any options yet but just wondering.

John

Don Fry22/06/2019 15:02:21
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4118 forum posts
48 photos

A windmilling prop causes more drag than a stationary prop, so your Robot will slow up a bit slower. The motor will stop where it wants to.

If you set it up as a tail dragger, the main is only an inch or so in front of the centre of gravity. A tail wheel/skid will auto rebalance it

Don Fry22/06/2019 15:45:35
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4118 forum posts
48 photos

In my experience, a stationary prop gets kicked out of the way if you belly land, most of the time

Dickw22/06/2019 15:56:28
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495 forum posts
76 photos

In a similar situation with an RC combat model without U/C and with a fixed prop I used the brake, and in addition used an IC prop which is stronger than the equivalent size electric prop. I rarely had a prop break after that.

Dick

Dwain Dibley.22/06/2019 19:27:16
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1270 forum posts
1265 photos

Ditto Don and Dick. Put the brake on and you wont break props, as I found out on my little "Webbitt"

D.D.

John Tee22/06/2019 21:52:34
792 forum posts
65 photos

Many thanks for the replies gents. I will try an I.C prop and the brake and see if there is any difference. Sorry for the late reply but have been out all afternoon and evening.

John

Trevor Crook23/06/2019 07:38:53
874 forum posts
65 photos

Shame you can't find a Kavan yellow nylon prop - ineffecient but it would be period and wouldn't break!

Simon Chaddock23/06/2019 10:02:16
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5483 forum posts
2878 photos

I can only endorse that a wind milling prop is much more likely to "catch" on the ground than a stationary one.

An ESC brake is 'dynamic' so the prop is still free to be pushed out of the way even though it has stopped rotating.

With no U/C the ground effect is stronger so a reduced actual touch down speed is possible. Every little helps. wink 2

John Tee23/06/2019 16:11:16
792 forum posts
65 photos

Reset the brake to on and fitted an i/c prop as DickW suggested and tried again today. Somehow got into programming mode on the esc and reset everything againindecision. As I didn't have the programming card with me I flew as was last time. Success I didn't break the prop. Will now reset the brake again.

Trevor I don't think I have a Kavan prop but I did find an old Keil Kraft white nylon prop of the right size in the junk pile so may try that.

Thanks again for your suggestions.

John

Stephen Jones23/06/2019 19:54:02
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2737 forum posts
1597 photos

Hi,

I fly a lot of models without landing gear as i consider them as dead weight and a cause of drag, I like to fly fast.

Having flown ic for many years the yellow Kavan props where a must and can still be bought.

However now i also fly electric and putting the break on does help. But i have thought about designing some sort of break system that would not only stop the propellor from turning but would also stop it in a horizontal position so as to avoid ground strike.

Steve.

Cliff 195923/06/2019 21:47:37
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280 forum posts
60 photos

Why not fit a folding prop, problem solved.

Bruce Collinson24/06/2019 13:10:16
409 forum posts

Just what I was thinking. Nose profile wrong?

BTC

Bruce Collinson24/06/2019 13:12:15
409 forum posts

OR a prop saver if it's a smallish model?

Don Fry24/06/2019 15:10:53
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4118 forum posts
48 photos

These things used to run on a 20 size 2 stroke.

John Tee24/06/2019 16:06:05
792 forum posts
65 photos

I first flew this one on a OS15 and it was way overpowered using the built in downthrust of the engine bearers. Now using an Eflite Power10 electric motor with an extra 3 degrees of downthrust and still need to put in more, so power is no issue. Did think of putting a folding prop on. It may work I will have to try but the nose is a three inch square (approx) so would need reshaping. Glides nicely without power , just had the problem with prop breaking on landing.

John

Don Fry24/06/2019 16:43:08
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4118 forum posts
48 photos

John, 1000's of Funfighters belly landed. Even running brittle efficient props, breakages were not that common, putting down on grass. Just stop the prop before contact.

PatMc24/06/2019 17:59:48
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4229 forum posts
521 photos
Posted by John Tee on 24/06/2019 16:06:05:

I first flew this one on a OS15 and it was way overpowered using the built in downthrust of the engine bearers. Now using an Eflite Power10 electric motor with an extra 3 degrees of downthrust and still need to put in more, so power is no issue. Did think of putting a folding prop on. It may work I will have to try but the nose is a three inch square (approx) so would need reshaping. Glides nicely without power , just had the problem with prop breaking on landing.

John

John, I built my Robot for ic using a paxolin plate to mount the motor to the wood bearers. I tried several different glow & diesel engines including a PAW19, Yin Yan 2.5cc, Fox 15 & Enya 09 III. The Fox & Enya were best power/weight match with the Enya slightly less powerful but better throttling.
Photo is after converting to electric using an inrunner on 2200 3s lipo. A whoopsy caused damage to the nose & the inrunner got replaced by a Turnigy 3536/1000 on 1800 3s lipo.

e-robot_inrunner.jpg

As you will see it has ailerons as well as elevator & rudder. Never broken a prop yet even when I damaged the nose area.
If you do use a folder there is no need to alter the nose profile as the folding action will bring the bottom blade back against the underside avoiding damage if the prop stops in a vertical position & if it stops horizontally it's not going to hit the ground anyway even though it will be prevented from folding.

BTW mine originally had the downthrust as per plan but I found the nose lifted when power was reduced, when I repaired the nose I zeroed the thrustline & it's fine. Can you not just use throttle control as a substitute for elevator when under power ?

Edited By PatMc on 24/06/2019 18:01:38

John Tee24/06/2019 23:11:08
792 forum posts
65 photos

PatMc. I have used the throttle once airborne and it flies a treat just on takeoff with a fair bit of power it has been known to loop on takeoff with a 3s battery. I have a selection of folding props but not sure if any are the right size. The Power10 manual suggests 10" - 12" props but I am using an 8" one. hate to think what the climb rate would be on 10". I could cheat and put an elevator on but that defeats the object. I only put throttle on as a safety feature.

John

John Tee24/06/2019 23:12:18
792 forum posts
65 photos

PatMc. I have used the throttle once airborne and it flies a treat just on takeoff with a fair bit of power it has been known to loop on takeoff with a 3s battery. I have a selection of folding props but not sure if any are the right size. The Power10 manual suggests 10" - 12" props but I am using an 8" one. hate to think what the climb rate would be on 10". I could cheat and put an elevator on but that defeats the object. I only put throttle on as a safety feature.

John

FlyinBrian25/06/2019 11:04:42
527 forum posts

I had a Robot in the late '60s early 70s. Originally single channel with a Frog 1.5cc diesel it eventually progressed to 3ch propo with a 2.5cc Oliver Tiger.

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