Pegasus Models Twin Hornet

[Tony H]

Hi All,

Just got in from an eventful and enjoyable maiden flight of my Pegasus Models Twin Hornet. The first flight was tricky and I was glad I had someone on hand to trim the plane because it needed loads of trim and it was very slight tail heavy even after I'd put a 6v battery and lead in the nose cone.

The ground control was very good with both engines running reliablely on song with each other. The problem arose on take off, as I suspected it was woefully under powered. I took a very long run up until it reached termal vellocity and pulled up a bit hoping to get a very low angled take off.

Unfortunately that wasn't to be as the plane was a bit tail heavy which meant it pulled up steeper than I'd intended, extremely close to stall speed. I then spent the next couple of mins with a club member trimming the plane like crazy until we finally got it flying fairly true and level.

The plane on Pegasus Models is marked up as 10/15 sized engines, I would say the plane would not fly on 10's and 15's are extreamely marginal and will only just take off with them. I would recomend 20/25's realistically to get decent takeoff speed.

I found once in the air trimmed the plane flew quite nicely and a decent cruise speed which on 15's is full throttle! and I landed her on about half throttle with power on the entire way with no wind.

The Yellow Jacket 15's fit really well are light and so far very reliable. It looks like I will have to try to get the maximum power out of them I can. I am currently running them on 8x4 props with 10% nitro fuel. Looks like I will need to up them to 8x5 or 8x6 props and 15% nitro to squeeze a bit more power.

I built the plane as light as possible but regreted putting the tail servos just behind the main wing, I would put them at the c of g next time as this caused me to put the battery and lead in the nose, though I believe even if I hadn't I still think it would need some extra weight in the nose, which is even more reason to put bigger 25s on the wings.

All in all fairly pleased, the plane would clearly fly much better with two 25's in as the 15's will just about allow her to take off (on the edge of stall) and do circuits fairly sedately on full throttle and maybe the odd roll. I wouldn't try much aerobatics with the 15s in.

Here are some photos just before the first flights.

?

Tony H

Edited By Tony H on 22/10/2016 15:16:03

Edited By Tony H on 22/10/2016 15:37:57

[flying pastor]

Tony, nice looking twin hornet but the engines get a poor write up on various USA forums. It seems that they are basically bored out .09's and are actually .0135's. Some figures that I saw quoted were 12,000rpm on 25percent nitro on an 8*4 prop. These figures are worse than an OS .15 la which in itself is not one of the most powerful .15's around. I suggest that you check the revs with a tachometer and go to a 5 in pitch prop but you may have to go down to a 7*5 and this may not suit the airframe. A friend had a couple of the .09's which worked well but were not long lasting.

All the best... Chris N.

[Tony H]

Hi Chris,

Thanks for you comments. My AP15'S are maxing out between 11,500 - 12,000 rpm on a 8x4. The instructions say the engines 8x4 is the recommended break in size for the engine and it's suggests a maximum size of 8x6 once bowen in. So i'l try that coupled with a 15% nitro fuel to boast the power a bit.

Edited By Tony H on 22/10/2016 16:26:14

Edited By Tony H on 22/10/2016 16:27:07

[Denis Watkins]

Tony, I have run through all the maths, and Just one 15 would maintain enough flight on a 5lb model that is airbourne, even if one motor went deadstick, so two should get the hornet off the ground. Stick to 8 x 4 props, they are correct. 25s are very powerful in comparison, but they are 50% heavier than a 15s. About 300 grammes heavier on the pair. Suggestion is to check the completed model weight as your power set is for 5lb max.

Edited By Denis Watkins on 22/10/2016 17:58:09

[Peter Miller]

I am sorry to have to tell you that the AP .15s are gutless compared with the SC 15. I know, some years ago I did a 1/12 scale flighter. It staggered round on the AP. Fitted an SC .15 and it went like a rocket.

[Tony H]

Hi Peter,

I have had all of the engines we are talking about SC25, OS15LA and AP15 and from my experience they are all a bit gutless however the SC15 certainly does have the most power overall. I would say the OS15LA was the least powerfull and the AP15's somewhere between the two.

I'm going to try leaning the mix a little more and put 8x6 props on the plane to hopefully give me a bit more performance. The AP's instructions say 8x6 for normal use after initial break in.

Hopefully that will also give me a little more inital speed to make take off more comfortable. I once had trainer plane with a 40 MDS engine in it (I know awful) the plane barely flew on the 10x6 someone sold it to me with but when I swapped it for a 11x6 it transformed the planes performance so fingers crossed the prop changes will do the trick.

Thanks for all you comments so far.

Tony H

Edited By Tony H on 22/10/2016 19:53:37

[Tony H]

UPDATE

I tried to get more power out of the AP15'S with 20% nitro fuel and a bigger prop and they ceased to run reliably. I decided to give up on the engines and switch them for 2 SC25's.

They enabled me to take all the ec tea weight out the nose which is good. I haven't flown with them yet but hopefully this weekend I will, they should give almost twice the power of the AP's.

[john stones 1 - Moderator]

Hope it go's well Tony, wrap up warm

John

[Tony H]

Thanks John

[Tony H]

Hi Guys,

Just flown my twin with two new SC25s attached flies sooooo much better and sounds perfectly in sync. However I have one snag the props are at their max diameter and I am getting 16,000rpm out of the 9x5 props I am using at the moment and I have put as big wheels as I can on it. So I'm now thinking of using 3 blade props but what is the rule for them do you drop down one in diameter of still stay at 9x5?

Tony H

[Tony Cook]

Hi Tony, I'm a bit late to this thread.. I have a 'skylark twin' 60 inch span that flies on two SC25's. Flies lovely even if the one of the engines cut. I'd seen the hornet many Years ago both in the mag and at the club. So it was a toss of the coin which to go for . I extended the front nose leg to get 9x6 props to clear the grass. Good luck with whatever you go for....and I agree' twin IC's in sync' sound great!!

[Tony H]

Hi Tony, I like your twin, mine hasn't got as big wingspan and so far not had an engine go out which i'm not looking forward too. It does sound and fly well now I've swapped my 15s for 25s.

I've just ordered a pair of 3 bladed 8x6 props and Domed Nuts from just engines delivered for ?29......ouch. I hope they do the trick. They should look cool also.

Tony H

Edited By Tony H on 02/04/2017 19:52:54

Edited By Tony H on 02/04/2017 19:53:20

[Tony Cook]

Hi Tony, thanks for the reply..the 3 bladed props will look and sound the business! BTW I made the front nose wheel steerable to aid tracking on take off. I also used one of my auxiliary switches to cut the throttles. When flying get used to using the rudder to see how it handles so when you do experience an engine out its no surprise. If all else fails the throttle cut will allow you to glide ( hopeully on the strip!) I've had my twin for about 4 years now.. experienced a couple of engine outs and used the throttle cut on 1 occassion. Plane still in 1 piece.. everyone loves the sound !!

[Tony H]

Thanks Tony. I've had 5 flights with the plane so far the first two on the 15s were scary but the ones with the two 25s are much better the plane even balanced better with them as no extra weight needed.
I'm looking forward to flying it again this weekend now I have put the 3 bladed props on it looks the biz. I just hope my adjusted c of g hasn't made it tail heavy in any way as it was a bit too nose heavy last time I flew.

Touch wood I have had no engine breadsticks yet and I hope to never have one. Maybe I try to fly it on rudder for a few circuits like you suggest just in case the worst happens.

I'll update with 3 bladed photo soon.

Tony H

[Tony Cook]

Hi Tony, slightly nose heavy is safe..if overly so wont be forgiving in the event of having to glide in. Looks like a great model so enjoy and look forward to future piccies. I will try and get a buddy to get some 'in flight' shots.. in which case I'll post them in due course. Cheers

[Tony H]

Thanks. I'll try to do the same.

[Tony H]

Hi Guys,

Here is an update of how my Twin Hornet looks now and a video of it flying on the new SC25's with 3 bladed props.