Steve Nash 1
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Posts posted by Steve Nash 1
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The Provost needs a good launch to get airborne, so what I have done is to glue a small piece of coarse sandpaper each side of the underneath just where my fingers grip it. This gives a good grip, and the sandpaper can be painted a matching colour if required. I hold it as shown with one finger just inside the cheat hole to give good leverage when I throw it. I get a really good chuck doing it like this.
Edited By Steve Nash 1 on 23/12/2019 10:44:06
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Tim, very interesting results. The best approach with these models I think is to keep them light and make the cheat holes bigger like you gave done. Its great that you have achieved almost 100% of the thrust quoted in the specs for the fan.
Steve -
I`ve already built the Provost and started building the Gnat. The hunter plan is next on my list. Then the Phantom. Then the Mig 15. I`m gonna need a crate full of FMS fans at this rate! Love a Bae Hawk plan one day,Tony (hint hint)
Steve
Edited By Steve Nash 1 on 22/12/2019 12:01:37
Edited By Steve Nash 1 on 22/12/2019 12:02:14
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Another idea is to check the timing of the esc, as I read that this affects the performance of the motor. My esc was from another plane which had an outrunner swinging a prop. In that plane I had the esc set to low timing. In the Provost I have set it to medium timing due to the high rpm required.
Steve
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Barry,
lovely looking model you've made there, I've just started building mine.
I measured the thrust on my Provost using a digital hanging scales. I suspend the plane from the tail using a string loop around the tail and zero the scales. Then just open up the throttle and see what you get. I got 530g thrust on the Provost with a freshly charged battery that had been kept warm in my pocket for a while, otherwise the lipo's don't perform very well this time of the year when they are cold. That 530g is on a 3s fan using an Overlander 3s 2200 battery. After a while the thrust dropped down gradually to around 515g. I would have thought that your 4s fan should perform better than that.
You say that you would only save a couple of ounces by swapping to 3s, but on an aircraft that should weigh around 20-22 oz that is 10% of the weight, so it will make a difference. On a 40 size IC plane a couple of ounces wouldn't even show a difference, but on models like this weight is the enemy.
Steve
Edited By Steve Nash 1 on 21/12/2019 21:13:02
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Have just done some thrust tests on the JP.
I have enlarged the cheat hole a little bit by 10mm in width and 15mm in length.
the thrust with a fully charged battery was 530g, so I'm quite pleased with that. I did do jt with the top cover off and the result was about the same, so I wont bother making any extra holes in the top.
Steve
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Hi Philip,
very interesting results from your edf thrust tests.
If only we could utilise all of that 620g thrust, the JP would be a totally transformed beast !
Based on your results I might increase the cheat hole a bit more niw.
Steve
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Hi Ray,
your JP is coming along nicely.
yes my battery is right up the front and also the 1.3 oz lead as far forward as I can get it. Before I lightened it it had an extra ounce of lead in the front, so I've taken that out as well as everything else I changed.
other flyers have reported the same tail heaviness and needed lead, or a bigger heavier battery (2700 ish).
If I was to build another I would add more lightening holes than I did on this one. I had already finished it all so didn't want to have to re-do all the stickers again.Lightening holes are ok as long as the structure is still strong. I always do round holes or at least square holes with rounded corners. Just remember that every gram too heavy at the back usually needs double at the front to counteract it. I've grabbed the fuselage and tried to twist and bend it and its rock solid still. If you decide to try it just don't overdo it.
Steve
Edited By Steve Nash 1 on 11/12/2019 21:20:36
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These are the lightening holes I made. The fuselage is still very strong and can't be flexed at all. Other changes were reducing the length of the esc wires, removing the aileron y-lead and plugging the servos straight into two seperate channels in the receiver, removing some blobs of hot glue that were holding wires, and removing the top hatch spring catch and fixing the hatch in place.
Steve
Edited By Steve Nash 1 on 11/12/2019 18:43:21
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Just had successful maiden flight of the Provost.
I did a few things to lighten the plane and it now weighs in at 27.6 oz including 2200 lipo and 1.3 oz lead.
i didn't have anyone to hand launch for me so I thought I would give it a go myself. There was a moderate breeze and I had kept the battery nice and warm in my pocket. I launched it just above head height with a firm chuck slightly upwards and it just flew away no problem, it didn't even sink a bit. The only thing I gave had to change is that I didn't have anywhere near enough elevator travel, but other than that it flew ok. I got about 5 mins from the 2200 which left 24% in the pack after landing. The landing was a bit firm due to the lack of elevator authority.
this was a total contrast to last weekends attempts to fly which resulted in belly flops onto the grass. Definitely better now it's lighter. I have a small piece of sandpaper glued each side of the underneath to grip better and had one finger in the entrance of the cheat hole to help push it forwards.Steve
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Alan,
were you also using a 2200 lipo?
I definitely think the plane needs seriously lightening at the back end. I have cut lightening holes in underside as it is easy to just cover with film, but doing sides, fin and tailplane means disturbing the finished stickers etc.
It could be altered during the build if I was to build another, with plenty of lightening holes in the rear. Maybe the wing could be moved back about 5mm or so if the intakes would still work out ok, that would hopefully take away the need for nose weight.Steve
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Hi Steve,
thats what happened to mine - a belly flop. Definitely a good throw needed.
I really wanted to stay with the 2200 lipo as I've started to build the Gnat too, and wanted the batteries to be for both planes instead of buying more different ones, so will prob settle for a bit of nose weight instead of bigger batt.
Steve
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Anyone weighed their Jet Provosts yet?
tried maiden flight at the weekend but seemed a little heavy. My hand launcher didn't quite give it enough oomph and it didn't fly off, just settled onto the grass.
have done bit of work to it to try and lighten it. I've cut some lightening holes in the underside rear fuselage and changed a few things. I've taken out about 1.5 oz.
mine now weighs in at 26.5 oz with a 2200 lipo but needs additional 1.3 - 1.5 oz of lead in the nose to achieve the C of G, making a total of just under 28 oz. I might try a 2700 lipo as that should come out the same but no lead needed. This time I will make sure lipo is at room temp to make sure it gives proper power.
if I was to build another I would cut lightening holes all round the rear fuselage and also the tailplane and fin. None of this would be seen after covering and would help take away a bit of the tail heavyness.
any thoughts ?
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Can't wait to build the Gnat too. I've just started cutting out the parts. I have the canopy and FMS fan ready. Just finishing the Provost, just fitting in receiver, connecting ailerons and sticking on intakes.
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Hi Trevor, thats how I did mine. There aren't too many parts to cut out. It is a lot cheaper that way 😀
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Apologies, actually you are right, they were 1/15 pilots that I got, not 1/12. I couldn’t find the receipt to check. I know they are a tiny bit small but no ones going to measure them to check. I think they look fine and They look better than having an empty cockpit.
Steve
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Yes they are 1970s/80s pilots in 1/12 scale. Not exactly right scale but not too bad
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Hi Simon, I got mine from realmodelpilots.co.uk
they are 3d printed in the scale of your choice.
steve
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This is my first one of Tony’s planes that I’ve built but I have seen many vids of others flying his designs successfully.
I’ve already photo copied the formers ready to stick on wood to start cutting out the Gnat as well.
i really love the Gnat, it looks awesome. I can’t decide which colour scene yet so I was considering building two. I’ve already got two more FMS fans from Bangood just in case. If I don’t, I might build either the hunter or his earlier designed Mig.
Steve
Edited By Steve Nash 1 on 14/11/2019 12:59:12
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Thanks Steve. I have heard a few people saying about the c of g, so I will check before I take it out flying.
I can get my pack right forward in the nose so hopefully I won’t need too much lead.
Steve
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Almost there !just got to connect the controls and fix the intakes on.
folland gnat plan now on bench ready to start next
Edited By Steve Nash 1 on 13/11/2019 23:55:26
Edited By Steve Nash 1 on 13/11/2019 23:56:20
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Another nice JP looking ace. I must say that so far this build has been the most I've used my razor plane for ages !!
New EDF Mini Jets- Jet Provost & Folland Gnat
in Tony Nijhuis plan builders
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Looking good, Tim.
been cutting out the formers and fuselage sides for my Gnat. Took quite a while, maybe I should have paid out for the Laser cut set from Tony. I brought the canopy though.